| // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 
 | // Use of this source code is governed by a BSD-style license that can be | 
 | // found in the LICENSE file. | 
 |  | 
 | #include "quic/core/quic_connection.h" | 
 |  | 
 | #include <string.h> | 
 | #include <sys/types.h> | 
 |  | 
 | #include <algorithm> | 
 | #include <iterator> | 
 | #include <limits> | 
 | #include <memory> | 
 | #include <optional> | 
 | #include <set> | 
 | #include <string> | 
 | #include <utility> | 
 |  | 
 | #include "absl/strings/escaping.h" | 
 | #include "absl/strings/str_cat.h" | 
 | #include "absl/strings/string_view.h" | 
 | #include "quic/core/congestion_control/rtt_stats.h" | 
 | #include "quic/core/congestion_control/send_algorithm_interface.h" | 
 | #include "quic/core/crypto/crypto_protocol.h" | 
 | #include "quic/core/crypto/crypto_utils.h" | 
 | #include "quic/core/crypto/quic_decrypter.h" | 
 | #include "quic/core/crypto/quic_encrypter.h" | 
 | #include "quic/core/proto/cached_network_parameters_proto.h" | 
 | #include "quic/core/quic_bandwidth.h" | 
 | #include "quic/core/quic_config.h" | 
 | #include "quic/core/quic_connection_id.h" | 
 | #include "quic/core/quic_constants.h" | 
 | #include "quic/core/quic_error_codes.h" | 
 | #include "quic/core/quic_legacy_version_encapsulator.h" | 
 | #include "quic/core/quic_packet_creator.h" | 
 | #include "quic/core/quic_packet_writer.h" | 
 | #include "quic/core/quic_path_validator.h" | 
 | #include "quic/core/quic_types.h" | 
 | #include "quic/core/quic_utils.h" | 
 | #include "quic/platform/api/quic_bug_tracker.h" | 
 | #include "quic/platform/api/quic_client_stats.h" | 
 | #include "quic/platform/api/quic_error_code_wrappers.h" | 
 | #include "quic/platform/api/quic_exported_stats.h" | 
 | #include "quic/platform/api/quic_flag_utils.h" | 
 | #include "quic/platform/api/quic_flags.h" | 
 | #include "quic/platform/api/quic_hostname_utils.h" | 
 | #include "quic/platform/api/quic_logging.h" | 
 | #include "quic/platform/api/quic_server_stats.h" | 
 | #include "quic/platform/api/quic_socket_address.h" | 
 | #include "common/platform/api/quiche_flag_utils.h" | 
 | #include "common/quiche_text_utils.h" | 
 |  | 
 | namespace quic { | 
 |  | 
 | class QuicDecrypter; | 
 | class QuicEncrypter; | 
 |  | 
 | namespace { | 
 |  | 
 | // Maximum number of consecutive sent nonretransmittable packets. | 
 | const QuicPacketCount kMaxConsecutiveNonRetransmittablePackets = 19; | 
 |  | 
 | // The minimum release time into future in ms. | 
 | const int kMinReleaseTimeIntoFutureMs = 1; | 
 |  | 
 | // Base class of all alarms owned by a QuicConnection. | 
 | class QuicConnectionAlarmDelegate : public QuicAlarm::Delegate { | 
 |  public: | 
 |   explicit QuicConnectionAlarmDelegate(QuicConnection* connection) | 
 |       : connection_(connection) {} | 
 |   QuicConnectionAlarmDelegate(const QuicConnectionAlarmDelegate&) = delete; | 
 |   QuicConnectionAlarmDelegate& operator=(const QuicConnectionAlarmDelegate&) = | 
 |       delete; | 
 |  | 
 |   QuicConnectionContext* GetConnectionContext() override { | 
 |     return (connection_ == nullptr) ? nullptr : connection_->context(); | 
 |   } | 
 |  | 
 |  protected: | 
 |   QuicConnection* connection_; | 
 | }; | 
 |  | 
 | // An alarm that is scheduled to send an ack if a timeout occurs. | 
 | class AckAlarmDelegate : public QuicConnectionAlarmDelegate { | 
 |  public: | 
 |   using QuicConnectionAlarmDelegate::QuicConnectionAlarmDelegate; | 
 |  | 
 |   void OnAlarm() override { | 
 |     QUICHE_DCHECK(connection_->ack_frame_updated()); | 
 |     QUICHE_DCHECK(connection_->connected()); | 
 |     QuicConnection::ScopedPacketFlusher flusher(connection_); | 
 |     if (connection_->SupportsMultiplePacketNumberSpaces()) { | 
 |       connection_->SendAllPendingAcks(); | 
 |     } else { | 
 |       connection_->SendAck(); | 
 |     } | 
 |   } | 
 | }; | 
 |  | 
 | // This alarm will be scheduled any time a data-bearing packet is sent out. | 
 | // When the alarm goes off, the connection checks to see if the oldest packets | 
 | // have been acked, and retransmit them if they have not. | 
 | class RetransmissionAlarmDelegate : public QuicConnectionAlarmDelegate { | 
 |  public: | 
 |   using QuicConnectionAlarmDelegate::QuicConnectionAlarmDelegate; | 
 |  | 
 |   void OnAlarm() override { | 
 |     QUICHE_DCHECK(connection_->connected()); | 
 |     connection_->OnRetransmissionTimeout(); | 
 |   } | 
 | }; | 
 |  | 
 | // An alarm that is scheduled when the SentPacketManager requires a delay | 
 | // before sending packets and fires when the packet may be sent. | 
 | class SendAlarmDelegate : public QuicConnectionAlarmDelegate { | 
 |  public: | 
 |   using QuicConnectionAlarmDelegate::QuicConnectionAlarmDelegate; | 
 |  | 
 |   void OnAlarm() override { | 
 |     QUICHE_DCHECK(connection_->connected()); | 
 |     connection_->WriteIfNotBlocked(); | 
 |   } | 
 | }; | 
 |  | 
 | class PingAlarmDelegate : public QuicConnectionAlarmDelegate { | 
 |  public: | 
 |   using QuicConnectionAlarmDelegate::QuicConnectionAlarmDelegate; | 
 |  | 
 |   void OnAlarm() override { | 
 |     QUICHE_DCHECK(connection_->connected()); | 
 |     connection_->OnPingTimeout(); | 
 |   } | 
 | }; | 
 |  | 
 | class MtuDiscoveryAlarmDelegate : public QuicConnectionAlarmDelegate { | 
 |  public: | 
 |   using QuicConnectionAlarmDelegate::QuicConnectionAlarmDelegate; | 
 |  | 
 |   void OnAlarm() override { | 
 |     QUICHE_DCHECK(connection_->connected()); | 
 |     connection_->DiscoverMtu(); | 
 |   } | 
 | }; | 
 |  | 
 | class ProcessUndecryptablePacketsAlarmDelegate | 
 |     : public QuicConnectionAlarmDelegate { | 
 |  public: | 
 |   using QuicConnectionAlarmDelegate::QuicConnectionAlarmDelegate; | 
 |  | 
 |   void OnAlarm() override { | 
 |     QUICHE_DCHECK(connection_->connected()); | 
 |     QuicConnection::ScopedPacketFlusher flusher(connection_); | 
 |     connection_->MaybeProcessUndecryptablePackets(); | 
 |   } | 
 | }; | 
 |  | 
 | class DiscardPreviousOneRttKeysAlarmDelegate | 
 |     : public QuicConnectionAlarmDelegate { | 
 |  public: | 
 |   using QuicConnectionAlarmDelegate::QuicConnectionAlarmDelegate; | 
 |  | 
 |   void OnAlarm() override { | 
 |     QUICHE_DCHECK(connection_->connected()); | 
 |     connection_->DiscardPreviousOneRttKeys(); | 
 |   } | 
 | }; | 
 |  | 
 | class DiscardZeroRttDecryptionKeysAlarmDelegate | 
 |     : public QuicConnectionAlarmDelegate { | 
 |  public: | 
 |   using QuicConnectionAlarmDelegate::QuicConnectionAlarmDelegate; | 
 |  | 
 |   void OnAlarm() override { | 
 |     QUICHE_DCHECK(connection_->connected()); | 
 |     QUIC_DLOG(INFO) << "0-RTT discard alarm fired"; | 
 |     connection_->RemoveDecrypter(ENCRYPTION_ZERO_RTT); | 
 |   } | 
 | }; | 
 |  | 
 | // When the clearer goes out of scope, the coalesced packet gets cleared. | 
 | class ScopedCoalescedPacketClearer { | 
 |  public: | 
 |   explicit ScopedCoalescedPacketClearer(QuicCoalescedPacket* coalesced) | 
 |       : coalesced_(coalesced) {} | 
 |   ~ScopedCoalescedPacketClearer() { coalesced_->Clear(); } | 
 |  | 
 |  private: | 
 |   QuicCoalescedPacket* coalesced_;  // Unowned. | 
 | }; | 
 |  | 
 | // Whether this incoming packet is allowed to replace our connection ID. | 
 | bool PacketCanReplaceServerConnectionId(const QuicPacketHeader& header, | 
 |                                         Perspective perspective) { | 
 |   return perspective == Perspective::IS_CLIENT && | 
 |          header.form == IETF_QUIC_LONG_HEADER_PACKET && | 
 |          header.version.IsKnown() && | 
 |          header.version.AllowsVariableLengthConnectionIds() && | 
 |          (header.long_packet_type == INITIAL || | 
 |           header.long_packet_type == RETRY); | 
 | } | 
 |  | 
 | CongestionControlType GetDefaultCongestionControlType() { | 
 |   if (GetQuicReloadableFlag(quic_default_to_bbr_v2)) { | 
 |     return kBBRv2; | 
 |   } | 
 |  | 
 |   if (GetQuicReloadableFlag(quic_default_to_bbr)) { | 
 |     return kBBR; | 
 |   } | 
 |  | 
 |   return kCubicBytes; | 
 | } | 
 |  | 
 | }  // namespace | 
 |  | 
 | #define ENDPOINT \ | 
 |   (perspective_ == Perspective::IS_SERVER ? "Server: " : "Client: ") | 
 |  | 
 | QuicConnection::QuicConnection( | 
 |     QuicConnectionId server_connection_id, | 
 |     QuicSocketAddress initial_self_address, | 
 |     QuicSocketAddress initial_peer_address, | 
 |     QuicConnectionHelperInterface* helper, QuicAlarmFactory* alarm_factory, | 
 |     QuicPacketWriter* writer, bool owns_writer, Perspective perspective, | 
 |     const ParsedQuicVersionVector& supported_versions) | 
 |     : framer_(supported_versions, helper->GetClock()->ApproximateNow(), | 
 |               perspective, server_connection_id.length()), | 
 |       current_packet_content_(NO_FRAMES_RECEIVED), | 
 |       is_current_packet_connectivity_probing_(false), | 
 |       has_path_challenge_in_current_packet_(false), | 
 |       current_effective_peer_migration_type_(NO_CHANGE), | 
 |       helper_(helper), | 
 |       alarm_factory_(alarm_factory), | 
 |       per_packet_options_(nullptr), | 
 |       writer_(writer), | 
 |       owns_writer_(owns_writer), | 
 |       encryption_level_(ENCRYPTION_INITIAL), | 
 |       clock_(helper->GetClock()), | 
 |       random_generator_(helper->GetRandomGenerator()), | 
 |       client_connection_id_is_set_(false), | 
 |       direct_peer_address_(initial_peer_address), | 
 |       default_path_(initial_self_address, QuicSocketAddress(), | 
 |                     /*client_connection_id=*/EmptyQuicConnectionId(), | 
 |                     server_connection_id, | 
 |                     /*stateless_reset_token=*/absl::nullopt), | 
 |       active_effective_peer_migration_type_(NO_CHANGE), | 
 |       support_key_update_for_connection_(false), | 
 |       last_packet_decrypted_(false), | 
 |       last_size_(0), | 
 |       current_packet_data_(nullptr), | 
 |       last_decrypted_packet_level_(ENCRYPTION_INITIAL), | 
 |       should_last_packet_instigate_acks_(false), | 
 |       max_undecryptable_packets_(0), | 
 |       max_tracked_packets_(GetQuicFlag(FLAGS_quic_max_tracked_packet_count)), | 
 |       idle_timeout_connection_close_behavior_( | 
 |           ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET), | 
 |       num_rtos_for_blackhole_detection_(0), | 
 |       uber_received_packet_manager_(&stats_), | 
 |       stop_waiting_count_(0), | 
 |       pending_retransmission_alarm_(false), | 
 |       defer_send_in_response_to_packets_(false), | 
 |       ping_timeout_(QuicTime::Delta::FromSeconds(kPingTimeoutSecs)), | 
 |       initial_retransmittable_on_wire_timeout_(QuicTime::Delta::Infinite()), | 
 |       consecutive_retransmittable_on_wire_ping_count_(0), | 
 |       retransmittable_on_wire_ping_count_(0), | 
 |       arena_(), | 
 |       ack_alarm_(alarm_factory_->CreateAlarm(arena_.New<AckAlarmDelegate>(this), | 
 |                                              &arena_)), | 
 |       retransmission_alarm_(alarm_factory_->CreateAlarm( | 
 |           arena_.New<RetransmissionAlarmDelegate>(this), &arena_)), | 
 |       send_alarm_(alarm_factory_->CreateAlarm( | 
 |           arena_.New<SendAlarmDelegate>(this), &arena_)), | 
 |       ping_alarm_(alarm_factory_->CreateAlarm( | 
 |           arena_.New<PingAlarmDelegate>(this), &arena_)), | 
 |       mtu_discovery_alarm_(alarm_factory_->CreateAlarm( | 
 |           arena_.New<MtuDiscoveryAlarmDelegate>(this), &arena_)), | 
 |       process_undecryptable_packets_alarm_(alarm_factory_->CreateAlarm( | 
 |           arena_.New<ProcessUndecryptablePacketsAlarmDelegate>(this), &arena_)), | 
 |       discard_previous_one_rtt_keys_alarm_(alarm_factory_->CreateAlarm( | 
 |           arena_.New<DiscardPreviousOneRttKeysAlarmDelegate>(this), &arena_)), | 
 |       discard_zero_rtt_decryption_keys_alarm_(alarm_factory_->CreateAlarm( | 
 |           arena_.New<DiscardZeroRttDecryptionKeysAlarmDelegate>(this), | 
 |           &arena_)), | 
 |       visitor_(nullptr), | 
 |       debug_visitor_(nullptr), | 
 |       packet_creator_(server_connection_id, &framer_, random_generator_, this), | 
 |       last_received_packet_info_(clock_->ApproximateNow()), | 
 |       sent_packet_manager_(perspective, clock_, random_generator_, &stats_, | 
 |                            GetDefaultCongestionControlType()), | 
 |       version_negotiated_(false), | 
 |       perspective_(perspective), | 
 |       connected_(true), | 
 |       can_truncate_connection_ids_(perspective == Perspective::IS_SERVER), | 
 |       mtu_probe_count_(0), | 
 |       previous_validated_mtu_(0), | 
 |       peer_max_packet_size_(kDefaultMaxPacketSizeTransportParam), | 
 |       largest_received_packet_size_(0), | 
 |       write_error_occurred_(false), | 
 |       no_stop_waiting_frames_(version().HasIetfInvariantHeader()), | 
 |       consecutive_num_packets_with_no_retransmittable_frames_(0), | 
 |       max_consecutive_num_packets_with_no_retransmittable_frames_( | 
 |           kMaxConsecutiveNonRetransmittablePackets), | 
 |       bundle_retransmittable_with_pto_ack_(false), | 
 |       fill_up_link_during_probing_(false), | 
 |       probing_retransmission_pending_(false), | 
 |       last_control_frame_id_(kInvalidControlFrameId), | 
 |       is_path_degrading_(false), | 
 |       processing_ack_frame_(false), | 
 |       supports_release_time_(false), | 
 |       release_time_into_future_(QuicTime::Delta::Zero()), | 
 |       blackhole_detector_(this, &arena_, alarm_factory_, &context_), | 
 |       idle_network_detector_(this, clock_->ApproximateNow(), &arena_, | 
 |                              alarm_factory_, &context_), | 
 |       path_validator_(alarm_factory_, &arena_, this, random_generator_, | 
 |                       &context_), | 
 |       most_recent_frame_type_(NUM_FRAME_TYPES) { | 
 |   QUICHE_DCHECK(perspective_ == Perspective::IS_CLIENT || | 
 |                 default_path_.self_address.IsInitialized()); | 
 |  | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "Created connection with server connection ID " | 
 |                   << server_connection_id | 
 |                   << " and version: " << ParsedQuicVersionToString(version()); | 
 |  | 
 |   QUIC_BUG_IF(quic_bug_12714_2, !QuicUtils::IsConnectionIdValidForVersion( | 
 |                                     server_connection_id, transport_version())) | 
 |       << "QuicConnection: attempted to use server connection ID " | 
 |       << server_connection_id << " which is invalid with version " << version(); | 
 |   framer_.set_visitor(this); | 
 |   stats_.connection_creation_time = clock_->ApproximateNow(); | 
 |   // TODO(ianswett): Supply the NetworkChangeVisitor as a constructor argument | 
 |   // and make it required non-null, because it's always used. | 
 |   sent_packet_manager_.SetNetworkChangeVisitor(this); | 
 |   if (GetQuicRestartFlag(quic_offload_pacing_to_usps2)) { | 
 |     sent_packet_manager_.SetPacingAlarmGranularity(QuicTime::Delta::Zero()); | 
 |     release_time_into_future_ = | 
 |         QuicTime::Delta::FromMilliseconds(kMinReleaseTimeIntoFutureMs); | 
 |   } | 
 |   // Allow the packet writer to potentially reduce the packet size to a value | 
 |   // even smaller than kDefaultMaxPacketSize. | 
 |   SetMaxPacketLength(perspective_ == Perspective::IS_SERVER | 
 |                          ? kDefaultServerMaxPacketSize | 
 |                          : kDefaultMaxPacketSize); | 
 |   uber_received_packet_manager_.set_max_ack_ranges(255); | 
 |   MaybeEnableMultiplePacketNumberSpacesSupport(); | 
 |   QUICHE_DCHECK(perspective_ == Perspective::IS_CLIENT || | 
 |                 supported_versions.size() == 1); | 
 |   InstallInitialCrypters(default_path_.server_connection_id); | 
 |  | 
 |   // On the server side, version negotiation has been done by the dispatcher, | 
 |   // and the server connection is created with the right version. | 
 |   if (perspective_ == Perspective::IS_SERVER) { | 
 |     SetVersionNegotiated(); | 
 |   } | 
 |   if (default_enable_5rto_blackhole_detection_) { | 
 |     num_rtos_for_blackhole_detection_ = 5; | 
 |     if (GetQuicReloadableFlag(quic_disable_server_blackhole_detection) && | 
 |         perspective_ == Perspective::IS_SERVER) { | 
 |       QUIC_RELOADABLE_FLAG_COUNT(quic_disable_server_blackhole_detection); | 
 |       blackhole_detection_disabled_ = true; | 
 |     } | 
 |   } | 
 |   packet_creator_.SetDefaultPeerAddress(initial_peer_address); | 
 | } | 
 |  | 
 | void QuicConnection::InstallInitialCrypters(QuicConnectionId connection_id) { | 
 |   CrypterPair crypters; | 
 |   CryptoUtils::CreateInitialObfuscators(perspective_, version(), connection_id, | 
 |                                         &crypters); | 
 |   SetEncrypter(ENCRYPTION_INITIAL, std::move(crypters.encrypter)); | 
 |   if (version().KnowsWhichDecrypterToUse()) { | 
 |     InstallDecrypter(ENCRYPTION_INITIAL, std::move(crypters.decrypter)); | 
 |   } else { | 
 |     SetDecrypter(ENCRYPTION_INITIAL, std::move(crypters.decrypter)); | 
 |   } | 
 | } | 
 |  | 
 | QuicConnection::~QuicConnection() { | 
 |   QUICHE_DCHECK_GE(stats_.max_egress_mtu, long_term_mtu_); | 
 |   if (owns_writer_) { | 
 |     delete writer_; | 
 |   } | 
 |   ClearQueuedPackets(); | 
 |   if (stats_ | 
 |           .num_tls_server_zero_rtt_packets_received_after_discarding_decrypter > | 
 |       0) { | 
 |     QUIC_CODE_COUNT_N( | 
 |         quic_server_received_tls_zero_rtt_packet_after_discarding_decrypter, 2, | 
 |         3); | 
 |   } else { | 
 |     QUIC_CODE_COUNT_N( | 
 |         quic_server_received_tls_zero_rtt_packet_after_discarding_decrypter, 3, | 
 |         3); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::ClearQueuedPackets() { | 
 |   buffered_packets_.clear(); | 
 | } | 
 |  | 
 | bool QuicConnection::ValidateConfigConnectionIds(const QuicConfig& config) { | 
 |   QUICHE_DCHECK(config.negotiated()); | 
 |   if (!version().UsesTls()) { | 
 |     // QUIC+TLS is required to transmit connection ID transport parameters. | 
 |     return true; | 
 |   } | 
 |   // This function validates connection IDs as defined in IETF draft-28 and | 
 |   // later. | 
 |  | 
 |   // Validate initial_source_connection_id. | 
 |   QuicConnectionId expected_initial_source_connection_id; | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     expected_initial_source_connection_id = default_path_.server_connection_id; | 
 |   } else { | 
 |     expected_initial_source_connection_id = default_path_.client_connection_id; | 
 |   } | 
 |   if (!config.HasReceivedInitialSourceConnectionId() || | 
 |       config.ReceivedInitialSourceConnectionId() != | 
 |           expected_initial_source_connection_id) { | 
 |     std::string received_value; | 
 |     if (config.HasReceivedInitialSourceConnectionId()) { | 
 |       received_value = config.ReceivedInitialSourceConnectionId().ToString(); | 
 |     } else { | 
 |       received_value = "none"; | 
 |     } | 
 |     std::string error_details = | 
 |         absl::StrCat("Bad initial_source_connection_id: expected ", | 
 |                      expected_initial_source_connection_id.ToString(), | 
 |                      ", received ", received_value); | 
 |     CloseConnection(IETF_QUIC_PROTOCOL_VIOLATION, error_details, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     // Validate original_destination_connection_id. | 
 |     if (!config.HasReceivedOriginalConnectionId() || | 
 |         config.ReceivedOriginalConnectionId() != | 
 |             GetOriginalDestinationConnectionId()) { | 
 |       std::string received_value; | 
 |       if (config.HasReceivedOriginalConnectionId()) { | 
 |         received_value = config.ReceivedOriginalConnectionId().ToString(); | 
 |       } else { | 
 |         received_value = "none"; | 
 |       } | 
 |       std::string error_details = | 
 |           absl::StrCat("Bad original_destination_connection_id: expected ", | 
 |                        GetOriginalDestinationConnectionId().ToString(), | 
 |                        ", received ", received_value); | 
 |       CloseConnection(IETF_QUIC_PROTOCOL_VIOLATION, error_details, | 
 |                       ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |       return false; | 
 |     } | 
 |     // Validate retry_source_connection_id. | 
 |     if (retry_source_connection_id_.has_value()) { | 
 |       // We received a RETRY packet, validate that the retry source | 
 |       // connection ID from the config matches the one from the RETRY. | 
 |       if (!config.HasReceivedRetrySourceConnectionId() || | 
 |           config.ReceivedRetrySourceConnectionId() != | 
 |               retry_source_connection_id_.value()) { | 
 |         std::string received_value; | 
 |         if (config.HasReceivedRetrySourceConnectionId()) { | 
 |           received_value = config.ReceivedRetrySourceConnectionId().ToString(); | 
 |         } else { | 
 |           received_value = "none"; | 
 |         } | 
 |         std::string error_details = | 
 |             absl::StrCat("Bad retry_source_connection_id: expected ", | 
 |                          retry_source_connection_id_.value().ToString(), | 
 |                          ", received ", received_value); | 
 |         CloseConnection(IETF_QUIC_PROTOCOL_VIOLATION, error_details, | 
 |                         ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |         return false; | 
 |       } | 
 |     } else { | 
 |       // We did not receive a RETRY packet, make sure we did not receive the | 
 |       // retry_source_connection_id transport parameter. | 
 |       if (config.HasReceivedRetrySourceConnectionId()) { | 
 |         std::string error_details = absl::StrCat( | 
 |             "Bad retry_source_connection_id: did not receive RETRY but " | 
 |             "received ", | 
 |             config.ReceivedRetrySourceConnectionId().ToString()); | 
 |         CloseConnection(IETF_QUIC_PROTOCOL_VIOLATION, error_details, | 
 |                         ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |         return false; | 
 |       } | 
 |     } | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::SetFromConfig(const QuicConfig& config) { | 
 |   if (config.negotiated()) { | 
 |     // Handshake complete, set handshake timeout to Infinite. | 
 |     SetNetworkTimeouts(QuicTime::Delta::Infinite(), | 
 |                        config.IdleNetworkTimeout()); | 
 |     idle_timeout_connection_close_behavior_ = | 
 |         ConnectionCloseBehavior::SILENT_CLOSE; | 
 |     if (perspective_ == Perspective::IS_SERVER) { | 
 |       idle_timeout_connection_close_behavior_ = ConnectionCloseBehavior:: | 
 |           SILENT_CLOSE_WITH_CONNECTION_CLOSE_PACKET_SERIALIZED; | 
 |     } | 
 |     if (config.HasClientRequestedIndependentOption(kNSLC, perspective_)) { | 
 |       idle_timeout_connection_close_behavior_ = | 
 |           ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET; | 
 |     } | 
 |     if (!ValidateConfigConnectionIds(config)) { | 
 |       return; | 
 |     } | 
 |     support_key_update_for_connection_ = | 
 |         config.KeyUpdateSupportedForConnection(); | 
 |     framer_.SetKeyUpdateSupportForConnection( | 
 |         support_key_update_for_connection_); | 
 |   } else { | 
 |     SetNetworkTimeouts(config.max_time_before_crypto_handshake(), | 
 |                        config.max_idle_time_before_crypto_handshake()); | 
 |     if (config.HasClientRequestedIndependentOption(kNCHP, perspective_)) { | 
 |       packet_creator_.set_chaos_protection_enabled(false); | 
 |     } | 
 |   } | 
 |  | 
 |   if (version().HasIetfQuicFrames() && | 
 |       config.HasReceivedPreferredAddressConnectionIdAndToken()) { | 
 |     QuicNewConnectionIdFrame frame; | 
 |     std::tie(frame.connection_id, frame.stateless_reset_token) = | 
 |         config.ReceivedPreferredAddressConnectionIdAndToken(); | 
 |     frame.sequence_number = 1u; | 
 |     frame.retire_prior_to = 0u; | 
 |     OnNewConnectionIdFrameInner(frame); | 
 |   } | 
 |  | 
 |   sent_packet_manager_.SetFromConfig(config); | 
 |   if (perspective_ == Perspective::IS_SERVER && | 
 |       config.HasClientSentConnectionOption(kAFF2, perspective_)) { | 
 |     send_ack_frequency_on_handshake_completion_ = true; | 
 |   } | 
 |   if (config.HasReceivedBytesForConnectionId() && | 
 |       can_truncate_connection_ids_) { | 
 |     packet_creator_.SetServerConnectionIdLength( | 
 |         config.ReceivedBytesForConnectionId()); | 
 |   } | 
 |   max_undecryptable_packets_ = config.max_undecryptable_packets(); | 
 |  | 
 |   if (!GetQuicReloadableFlag(quic_enable_mtu_discovery_at_server)) { | 
 |     if (config.HasClientRequestedIndependentOption(kMTUH, perspective_)) { | 
 |       SetMtuDiscoveryTarget(kMtuDiscoveryTargetPacketSizeHigh); | 
 |     } | 
 |   } | 
 |   if (config.HasClientRequestedIndependentOption(kMTUL, perspective_)) { | 
 |     SetMtuDiscoveryTarget(kMtuDiscoveryTargetPacketSizeLow); | 
 |   } | 
 |   if (default_enable_5rto_blackhole_detection_) { | 
 |     if (config.HasClientRequestedIndependentOption(kCBHD, perspective_)) { | 
 |       QUIC_CODE_COUNT(quic_client_only_blackhole_detection); | 
 |       blackhole_detection_disabled_ = true; | 
 |     } | 
 |     if (config.HasClientSentConnectionOption(kNBHD, perspective_)) { | 
 |       blackhole_detection_disabled_ = true; | 
 |     } | 
 |     if (config.HasClientSentConnectionOption(k2RTO, perspective_)) { | 
 |       QUIC_CODE_COUNT(quic_2rto_blackhole_detection); | 
 |       num_rtos_for_blackhole_detection_ = 2; | 
 |     } | 
 |     if (config.HasClientSentConnectionOption(k3RTO, perspective_)) { | 
 |       QUIC_CODE_COUNT(quic_3rto_blackhole_detection); | 
 |       num_rtos_for_blackhole_detection_ = 3; | 
 |     } | 
 |     if (config.HasClientSentConnectionOption(k4RTO, perspective_)) { | 
 |       QUIC_CODE_COUNT(quic_4rto_blackhole_detection); | 
 |       num_rtos_for_blackhole_detection_ = 4; | 
 |     } | 
 |     if (config.HasClientSentConnectionOption(k6RTO, perspective_)) { | 
 |       QUIC_CODE_COUNT(quic_6rto_blackhole_detection); | 
 |       num_rtos_for_blackhole_detection_ = 6; | 
 |     } | 
 |   } | 
 |  | 
 |   if (config.HasClientRequestedIndependentOption(kFIDT, perspective_)) { | 
 |     idle_network_detector_.enable_shorter_idle_timeout_on_sent_packet(); | 
 |   } | 
 |   if (config.HasClientRequestedIndependentOption(k3AFF, perspective_)) { | 
 |     anti_amplification_factor_ = 3; | 
 |   } | 
 |   if (config.HasClientRequestedIndependentOption(k10AF, perspective_)) { | 
 |     anti_amplification_factor_ = 10; | 
 |   } | 
 |  | 
 |   if (GetQuicReloadableFlag(quic_enable_server_on_wire_ping) && | 
 |       perspective_ == Perspective::IS_SERVER && | 
 |       config.HasClientSentConnectionOption(kSRWP, perspective_)) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT(quic_enable_server_on_wire_ping); | 
 |     set_initial_retransmittable_on_wire_timeout( | 
 |         QuicTime::Delta::FromMilliseconds(200)); | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnSetFromConfig(config); | 
 |   } | 
 |   uber_received_packet_manager_.SetFromConfig(config, perspective_); | 
 |   if (config.HasClientSentConnectionOption(k5RTO, perspective_)) { | 
 |     num_rtos_for_blackhole_detection_ = 5; | 
 |   } | 
 |   if (sent_packet_manager_.pto_enabled()) { | 
 |     if (config.HasClientSentConnectionOption(k6PTO, perspective_) || | 
 |         config.HasClientSentConnectionOption(k7PTO, perspective_) || | 
 |         config.HasClientSentConnectionOption(k8PTO, perspective_)) { | 
 |       num_rtos_for_blackhole_detection_ = 5; | 
 |     } | 
 |   } | 
 |   if (config.HasClientSentConnectionOption(kNSTP, perspective_)) { | 
 |     no_stop_waiting_frames_ = true; | 
 |   } | 
 |   if (config.HasReceivedStatelessResetToken()) { | 
 |     default_path_.stateless_reset_token = config.ReceivedStatelessResetToken(); | 
 |   } | 
 |   if (config.HasReceivedAckDelayExponent()) { | 
 |     framer_.set_peer_ack_delay_exponent(config.ReceivedAckDelayExponent()); | 
 |   } | 
 |   if (config.HasClientSentConnectionOption(kEACK, perspective_)) { | 
 |     bundle_retransmittable_with_pto_ack_ = true; | 
 |   } | 
 |   if (config.HasClientSentConnectionOption(kDFER, perspective_)) { | 
 |     defer_send_in_response_to_packets_ = false; | 
 |   } | 
 |   const bool remove_connection_migration_connection_option = | 
 |       GetQuicReloadableFlag(quic_remove_connection_migration_connection_option); | 
 |   if (remove_connection_migration_connection_option) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT( | 
 |         quic_remove_connection_migration_connection_option); | 
 |   } | 
 |   if (framer_.version().HasIetfQuicFrames() && use_path_validator_ && | 
 |       count_bytes_on_alternative_path_separately_ && | 
 |       GetQuicReloadableFlag(quic_server_reverse_validate_new_path3) && | 
 |       (remove_connection_migration_connection_option || | 
 |        config.HasClientSentConnectionOption(kRVCM, perspective_))) { | 
 |     QUIC_CODE_COUNT_N(quic_server_reverse_validate_new_path3, 6, 6); | 
 |     validate_client_addresses_ = true; | 
 |   } | 
 |   // Having connection_migration_use_new_cid_ depends on the same set of flags | 
 |   // and connection option on both client and server sides has the advantage of: | 
 |   // 1) Less chance of skew in using new connection ID or not between client | 
 |   //    and server in unit tests with random flag combinations. | 
 |   // 2) Client side's rollout can be protected by the same connection option. | 
 |   connection_migration_use_new_cid_ = | 
 |       validate_client_addresses_ && | 
 |       GetQuicReloadableFlag(quic_drop_unsent_path_response) && | 
 |       GetQuicReloadableFlag(quic_connection_migration_use_new_cid_v2); | 
 |   if (config.HasReceivedMaxPacketSize()) { | 
 |     peer_max_packet_size_ = config.ReceivedMaxPacketSize(); | 
 |     MaybeUpdatePacketCreatorMaxPacketLengthAndPadding(); | 
 |   } | 
 |   if (config.HasReceivedMaxDatagramFrameSize()) { | 
 |     packet_creator_.SetMaxDatagramFrameSize( | 
 |         config.ReceivedMaxDatagramFrameSize()); | 
 |   } | 
 |  | 
 |   supports_release_time_ = | 
 |       writer_ != nullptr && writer_->SupportsReleaseTime() && | 
 |       !config.HasClientSentConnectionOption(kNPCO, perspective_); | 
 |  | 
 |   if (supports_release_time_) { | 
 |     UpdateReleaseTimeIntoFuture(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::EnableLegacyVersionEncapsulation( | 
 |     const std::string& server_name) { | 
 |   if (perspective_ != Perspective::IS_CLIENT) { | 
 |     QUIC_BUG(quic_bug_10511_1) | 
 |         << "Cannot enable Legacy Version Encapsulation on the server"; | 
 |     return; | 
 |   } | 
 |   if (legacy_version_encapsulation_enabled_) { | 
 |     QUIC_BUG(quic_bug_10511_2) | 
 |         << "Do not call EnableLegacyVersionEncapsulation twice"; | 
 |     return; | 
 |   } | 
 |   if (!QuicHostnameUtils::IsValidSNI(server_name)) { | 
 |     // Legacy Version Encapsulation is only used when SNI is transmitted. | 
 |     QUIC_DLOG(INFO) | 
 |         << "Refusing to use Legacy Version Encapsulation with invalid SNI \"" | 
 |         << server_name << "\""; | 
 |     return; | 
 |   } | 
 |   QUIC_DLOG(INFO) << "Enabling Legacy Version Encapsulation with SNI \"" | 
 |                   << server_name << "\""; | 
 |   legacy_version_encapsulation_enabled_ = true; | 
 |   legacy_version_encapsulation_sni_ = server_name; | 
 | } | 
 |  | 
 | bool QuicConnection::MaybeTestLiveness() { | 
 |   QUICHE_DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |   if (encryption_level_ != ENCRYPTION_FORWARD_SECURE) { | 
 |     return false; | 
 |   } | 
 |   const QuicTime idle_network_deadline = | 
 |       idle_network_detector_.GetIdleNetworkDeadline(); | 
 |   if (!idle_network_deadline.IsInitialized()) { | 
 |     return false; | 
 |   } | 
 |   const QuicTime now = clock_->ApproximateNow(); | 
 |   if (now > idle_network_deadline) { | 
 |     QUIC_DLOG(WARNING) << "Idle network deadline has passed"; | 
 |     return false; | 
 |   } | 
 |   const QuicTime::Delta timeout = idle_network_deadline - now; | 
 |   if (2 * timeout > idle_network_detector_.idle_network_timeout()) { | 
 |     // Do not test liveness if timeout is > half timeout. This is used to | 
 |     // prevent an infinite loop for short idle timeout. | 
 |     return false; | 
 |   } | 
 |   if (!sent_packet_manager_.IsLessThanThreePTOs(timeout)) { | 
 |     return false; | 
 |   } | 
 |   SendConnectivityProbingPacket(writer_, peer_address()); | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::ApplyConnectionOptions( | 
 |     const QuicTagVector& connection_options) { | 
 |   sent_packet_manager_.ApplyConnectionOptions(connection_options); | 
 | } | 
 |  | 
 | void QuicConnection::OnSendConnectionState( | 
 |     const CachedNetworkParameters& cached_network_params) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnSendConnectionState(cached_network_params); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnReceiveConnectionState( | 
 |     const CachedNetworkParameters& cached_network_params) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnReceiveConnectionState(cached_network_params); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::ResumeConnectionState( | 
 |     const CachedNetworkParameters& cached_network_params, | 
 |     bool max_bandwidth_resumption) { | 
 |   sent_packet_manager_.ResumeConnectionState(cached_network_params, | 
 |                                              max_bandwidth_resumption); | 
 | } | 
 |  | 
 | void QuicConnection::SetMaxPacingRate(QuicBandwidth max_pacing_rate) { | 
 |   sent_packet_manager_.SetMaxPacingRate(max_pacing_rate); | 
 | } | 
 |  | 
 | void QuicConnection::AdjustNetworkParameters( | 
 |     const SendAlgorithmInterface::NetworkParams& params) { | 
 |   sent_packet_manager_.AdjustNetworkParameters(params); | 
 | } | 
 |  | 
 | void QuicConnection::SetLossDetectionTuner( | 
 |     std::unique_ptr<LossDetectionTunerInterface> tuner) { | 
 |   sent_packet_manager_.SetLossDetectionTuner(std::move(tuner)); | 
 | } | 
 |  | 
 | void QuicConnection::OnConfigNegotiated() { | 
 |   sent_packet_manager_.OnConfigNegotiated(); | 
 |  | 
 |   if (GetQuicReloadableFlag(quic_enable_mtu_discovery_at_server) && | 
 |       perspective_ == Perspective::IS_SERVER) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT(quic_enable_mtu_discovery_at_server); | 
 |     SetMtuDiscoveryTarget(kMtuDiscoveryTargetPacketSizeHigh); | 
 |   } | 
 | } | 
 |  | 
 | QuicBandwidth QuicConnection::MaxPacingRate() const { | 
 |   return sent_packet_manager_.MaxPacingRate(); | 
 | } | 
 |  | 
 | bool QuicConnection::SelectMutualVersion( | 
 |     const ParsedQuicVersionVector& available_versions) { | 
 |   // Try to find the highest mutual version by iterating over supported | 
 |   // versions, starting with the highest, and breaking out of the loop once we | 
 |   // find a matching version in the provided available_versions vector. | 
 |   const ParsedQuicVersionVector& supported_versions = | 
 |       framer_.supported_versions(); | 
 |   for (size_t i = 0; i < supported_versions.size(); ++i) { | 
 |     const ParsedQuicVersion& version = supported_versions[i]; | 
 |     if (std::find(available_versions.begin(), available_versions.end(), | 
 |                   version) != available_versions.end()) { | 
 |       framer_.set_version(version); | 
 |       return true; | 
 |     } | 
 |   } | 
 |  | 
 |   return false; | 
 | } | 
 |  | 
 | void QuicConnection::OnError(QuicFramer* framer) { | 
 |   // Packets that we can not or have not decrypted are dropped. | 
 |   // TODO(rch): add stats to measure this. | 
 |   if (!connected_ || last_packet_decrypted_ == false) { | 
 |     return; | 
 |   } | 
 |   CloseConnection(framer->error(), framer->detailed_error(), | 
 |                   ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 | } | 
 |  | 
 | void QuicConnection::OnPacket() { | 
 |   last_packet_decrypted_ = false; | 
 | } | 
 |  | 
 | void QuicConnection::OnPublicResetPacket(const QuicPublicResetPacket& packet) { | 
 |   // Check that any public reset packet with a different connection ID that was | 
 |   // routed to this QuicConnection has been redirected before control reaches | 
 |   // here.  (Check for a bug regression.) | 
 |   QUICHE_DCHECK_EQ(default_path_.server_connection_id, packet.connection_id); | 
 |   QUICHE_DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |   QUICHE_DCHECK(!version().HasIetfInvariantHeader()); | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPublicResetPacket(packet); | 
 |   } | 
 |   std::string error_details = "Received public reset."; | 
 |   if (perspective_ == Perspective::IS_CLIENT && !packet.endpoint_id.empty()) { | 
 |     absl::StrAppend(&error_details, " From ", packet.endpoint_id, "."); | 
 |   } | 
 |   QUIC_DLOG(INFO) << ENDPOINT << error_details; | 
 |   QUIC_CODE_COUNT(quic_tear_down_local_connection_on_public_reset); | 
 |   TearDownLocalConnectionState(QUIC_PUBLIC_RESET, NO_IETF_QUIC_ERROR, | 
 |                                error_details, ConnectionCloseSource::FROM_PEER); | 
 | } | 
 |  | 
 | bool QuicConnection::OnProtocolVersionMismatch( | 
 |     ParsedQuicVersion received_version) { | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "Received packet with mismatched version " | 
 |                   << ParsedQuicVersionToString(received_version); | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     const std::string error_details = "Protocol version mismatch."; | 
 |     QUIC_BUG(quic_bug_10511_3) << ENDPOINT << error_details; | 
 |     CloseConnection(QUIC_INTERNAL_ERROR, error_details, | 
 |                     ConnectionCloseBehavior::SILENT_CLOSE); | 
 |   } | 
 |  | 
 |   // Server drops old packets that were sent by the client before the version | 
 |   // was negotiated. | 
 |   return false; | 
 | } | 
 |  | 
 | // Handles version negotiation for client connection. | 
 | void QuicConnection::OnVersionNegotiationPacket( | 
 |     const QuicVersionNegotiationPacket& packet) { | 
 |   // Check that any public reset packet with a different connection ID that was | 
 |   // routed to this QuicConnection has been redirected before control reaches | 
 |   // here.  (Check for a bug regression.) | 
 |   QUICHE_DCHECK_EQ(default_path_.server_connection_id, packet.connection_id); | 
 |   if (perspective_ == Perspective::IS_SERVER) { | 
 |     const std::string error_details = | 
 |         "Server received version negotiation packet."; | 
 |     QUIC_BUG(quic_bug_10511_4) << error_details; | 
 |     QUIC_CODE_COUNT(quic_tear_down_local_connection_on_version_negotiation); | 
 |     CloseConnection(QUIC_INTERNAL_ERROR, error_details, | 
 |                     ConnectionCloseBehavior::SILENT_CLOSE); | 
 |     return; | 
 |   } | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnVersionNegotiationPacket(packet); | 
 |   } | 
 |  | 
 |   if (version_negotiated_) { | 
 |     // Possibly a duplicate version negotiation packet. | 
 |     return; | 
 |   } | 
 |  | 
 |   if (std::find(packet.versions.begin(), packet.versions.end(), version()) != | 
 |       packet.versions.end()) { | 
 |     const std::string error_details = absl::StrCat( | 
 |         "Server already supports client's version ", | 
 |         ParsedQuicVersionToString(version()), | 
 |         " and should have accepted the connection instead of sending {", | 
 |         ParsedQuicVersionVectorToString(packet.versions), "}."); | 
 |     QUIC_DLOG(WARNING) << error_details; | 
 |     CloseConnection(QUIC_INVALID_VERSION_NEGOTIATION_PACKET, error_details, | 
 |                     ConnectionCloseBehavior::SILENT_CLOSE); | 
 |     return; | 
 |   } | 
 |  | 
 |   server_supported_versions_ = packet.versions; | 
 |   CloseConnection( | 
 |       QUIC_INVALID_VERSION, | 
 |       absl::StrCat( | 
 |           "Client may support one of the versions in the server's list, but " | 
 |           "it's going to close the connection anyway. Supported versions: {", | 
 |           ParsedQuicVersionVectorToString(framer_.supported_versions()), | 
 |           "}, peer supported versions: {", | 
 |           ParsedQuicVersionVectorToString(packet.versions), "}"), | 
 |       ConnectionCloseBehavior::SILENT_CLOSE); | 
 | } | 
 |  | 
 | // Handles retry for client connection. | 
 | void QuicConnection::OnRetryPacket(QuicConnectionId original_connection_id, | 
 |                                    QuicConnectionId new_connection_id, | 
 |                                    absl::string_view retry_token, | 
 |                                    absl::string_view retry_integrity_tag, | 
 |                                    absl::string_view retry_without_tag) { | 
 |   QUICHE_DCHECK_EQ(Perspective::IS_CLIENT, perspective_); | 
 |   if (version().UsesTls()) { | 
 |     if (!CryptoUtils::ValidateRetryIntegrityTag( | 
 |             version(), default_path_.server_connection_id, retry_without_tag, | 
 |             retry_integrity_tag)) { | 
 |       QUIC_DLOG(ERROR) << "Ignoring RETRY with invalid integrity tag"; | 
 |       return; | 
 |     } | 
 |   } else { | 
 |     if (original_connection_id != default_path_.server_connection_id) { | 
 |       QUIC_DLOG(ERROR) << "Ignoring RETRY with original connection ID " | 
 |                        << original_connection_id << " not matching expected " | 
 |                        << default_path_.server_connection_id << " token " | 
 |                        << absl::BytesToHexString(retry_token); | 
 |       return; | 
 |     } | 
 |   } | 
 |   framer_.set_drop_incoming_retry_packets(true); | 
 |   stats_.retry_packet_processed = true; | 
 |   QUIC_DLOG(INFO) << "Received RETRY, replacing connection ID " | 
 |                   << default_path_.server_connection_id << " with " | 
 |                   << new_connection_id << ", received token " | 
 |                   << absl::BytesToHexString(retry_token); | 
 |   if (!original_destination_connection_id_.has_value()) { | 
 |     original_destination_connection_id_ = default_path_.server_connection_id; | 
 |   } | 
 |   QUICHE_DCHECK(!retry_source_connection_id_.has_value()) | 
 |       << retry_source_connection_id_.value(); | 
 |   retry_source_connection_id_ = new_connection_id; | 
 |   ReplaceInitialServerConnectionId(new_connection_id); | 
 |   packet_creator_.SetRetryToken(retry_token); | 
 |  | 
 |   // Reinstall initial crypters because the connection ID changed. | 
 |   InstallInitialCrypters(default_path_.server_connection_id); | 
 |  | 
 |   sent_packet_manager_.MarkInitialPacketsForRetransmission(); | 
 | } | 
 |  | 
 | void QuicConnection::SetOriginalDestinationConnectionId( | 
 |     const QuicConnectionId& original_destination_connection_id) { | 
 |   QUIC_DLOG(INFO) << "Setting original_destination_connection_id to " | 
 |                   << original_destination_connection_id | 
 |                   << " on connection with server_connection_id " | 
 |                   << default_path_.server_connection_id; | 
 |   QUICHE_DCHECK_NE(original_destination_connection_id, | 
 |                    default_path_.server_connection_id); | 
 |   InstallInitialCrypters(original_destination_connection_id); | 
 |   QUICHE_DCHECK(!original_destination_connection_id_.has_value()) | 
 |       << original_destination_connection_id_.value(); | 
 |   original_destination_connection_id_ = original_destination_connection_id; | 
 |   original_destination_connection_id_replacement_ = | 
 |       default_path_.server_connection_id; | 
 | } | 
 |  | 
 | QuicConnectionId QuicConnection::GetOriginalDestinationConnectionId() { | 
 |   if (original_destination_connection_id_.has_value()) { | 
 |     return original_destination_connection_id_.value(); | 
 |   } | 
 |   return default_path_.server_connection_id; | 
 | } | 
 |  | 
 | bool QuicConnection::ValidateServerConnectionId( | 
 |     const QuicPacketHeader& header) const { | 
 |   if (perspective_ == Perspective::IS_CLIENT && | 
 |       header.form == IETF_QUIC_SHORT_HEADER_PACKET) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   QuicConnectionId server_connection_id = | 
 |       GetServerConnectionIdAsRecipient(header, perspective_); | 
 |  | 
 |   if (server_connection_id == default_path_.server_connection_id || | 
 |       server_connection_id == original_destination_connection_id_) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (PacketCanReplaceServerConnectionId(header, perspective_)) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Accepting packet with new connection ID " | 
 |                     << server_connection_id << " instead of " | 
 |                     << default_path_.server_connection_id; | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (connection_migration_use_new_cid_ && | 
 |       perspective_ == Perspective::IS_SERVER && | 
 |       self_issued_cid_manager_ != nullptr && | 
 |       self_issued_cid_manager_->IsConnectionIdInUse(server_connection_id)) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   return false; | 
 | } | 
 |  | 
 | bool QuicConnection::OnUnauthenticatedPublicHeader( | 
 |     const QuicPacketHeader& header) { | 
 |   last_packet_destination_connection_id_ = header.destination_connection_id; | 
 |   // If last packet destination connection ID is the original server | 
 |   // connection ID chosen by client, replaces it with the connection ID chosen | 
 |   // by server. | 
 |   if (perspective_ == Perspective::IS_SERVER && | 
 |       original_destination_connection_id_.has_value() && | 
 |       last_packet_destination_connection_id_ == | 
 |           *original_destination_connection_id_) { | 
 |     last_packet_destination_connection_id_ = | 
 |         original_destination_connection_id_replacement_; | 
 |   } | 
 |  | 
 |   // As soon as we receive an initial we start ignoring subsequent retries. | 
 |   if (header.version_flag && header.long_packet_type == INITIAL) { | 
 |     framer_.set_drop_incoming_retry_packets(true); | 
 |   } | 
 |  | 
 |   if (!ValidateServerConnectionId(header)) { | 
 |     ++stats_.packets_dropped; | 
 |     QuicConnectionId server_connection_id = | 
 |         GetServerConnectionIdAsRecipient(header, perspective_); | 
 |     QUIC_DLOG(INFO) << ENDPOINT | 
 |                     << "Ignoring packet from unexpected server connection ID " | 
 |                     << server_connection_id << " instead of " | 
 |                     << default_path_.server_connection_id; | 
 |     if (debug_visitor_ != nullptr) { | 
 |       debug_visitor_->OnIncorrectConnectionId(server_connection_id); | 
 |     } | 
 |     // If this is a server, the dispatcher routes each packet to the | 
 |     // QuicConnection responsible for the packet's connection ID.  So if control | 
 |     // arrives here and this is a server, the dispatcher must be malfunctioning. | 
 |     QUICHE_DCHECK_NE(Perspective::IS_SERVER, perspective_); | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (!version().SupportsClientConnectionIds()) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (perspective_ == Perspective::IS_SERVER && | 
 |       header.form == IETF_QUIC_SHORT_HEADER_PACKET) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   QuicConnectionId client_connection_id = | 
 |       GetClientConnectionIdAsRecipient(header, perspective_); | 
 |  | 
 |   if (client_connection_id == default_path_.client_connection_id) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (!client_connection_id_is_set_ && perspective_ == Perspective::IS_SERVER) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT | 
 |                     << "Setting client connection ID from first packet to " | 
 |                     << client_connection_id; | 
 |     set_client_connection_id(client_connection_id); | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (connection_migration_use_new_cid_ && | 
 |       perspective_ == Perspective::IS_CLIENT && | 
 |       self_issued_cid_manager_ != nullptr && | 
 |       self_issued_cid_manager_->IsConnectionIdInUse(client_connection_id)) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   ++stats_.packets_dropped; | 
 |   QUIC_DLOG(INFO) << ENDPOINT | 
 |                   << "Ignoring packet from unexpected client connection ID " | 
 |                   << client_connection_id << " instead of " | 
 |                   << default_path_.client_connection_id; | 
 |   return false; | 
 | } | 
 |  | 
 | bool QuicConnection::OnUnauthenticatedHeader(const QuicPacketHeader& header) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnUnauthenticatedHeader(header); | 
 |   } | 
 |  | 
 |   // Sanity check on the server connection ID in header. | 
 |   QUICHE_DCHECK(ValidateServerConnectionId(header)); | 
 |  | 
 |   if (packet_creator_.HasPendingFrames()) { | 
 |     // Incoming packets may change a queued ACK frame. | 
 |     const std::string error_details = | 
 |         "Pending frames must be serialized before incoming packets are " | 
 |         "processed."; | 
 |     QUIC_BUG(quic_pending_frames_not_serialized) | 
 |         << error_details << ", received header: " << header; | 
 |     CloseConnection(QUIC_INTERNAL_ERROR, error_details, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |  | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::OnSuccessfulVersionNegotiation() { | 
 |   visitor_->OnSuccessfulVersionNegotiation(version()); | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnSuccessfulVersionNegotiation(version()); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnSuccessfulMigration(bool is_port_change) { | 
 |   QUICHE_DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |   if (IsPathDegrading()) { | 
 |     // If path was previously degrading, and migration is successful after | 
 |     // probing, restart the path degrading and blackhole detection. | 
 |     OnForwardProgressMade(); | 
 |   } | 
 |   if (IsAlternativePath(default_path_.self_address, | 
 |                         default_path_.peer_address)) { | 
 |     // Reset alternative path state even if it is still under validation. | 
 |     alternative_path_.Clear(); | 
 |   } | 
 |   // TODO(b/159074035): notify SentPacketManger with RTT sample from probing. | 
 |   if (version().HasIetfQuicFrames() && !is_port_change) { | 
 |     sent_packet_manager_.OnConnectionMigration(/*reset_send_algorithm=*/true); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnTransportParametersSent( | 
 |     const TransportParameters& transport_parameters) const { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnTransportParametersSent(transport_parameters); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnTransportParametersReceived( | 
 |     const TransportParameters& transport_parameters) const { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnTransportParametersReceived(transport_parameters); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnTransportParametersResumed( | 
 |     const TransportParameters& transport_parameters) const { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnTransportParametersResumed(transport_parameters); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::HasPendingAcks() const { | 
 |   return ack_alarm_->IsSet(); | 
 | } | 
 |  | 
 | void QuicConnection::OnUserAgentIdKnown(const std::string& /*user_agent_id*/) { | 
 |   sent_packet_manager_.OnUserAgentIdKnown(); | 
 | } | 
 |  | 
 | void QuicConnection::OnDecryptedPacket(size_t /*length*/, | 
 |                                        EncryptionLevel level) { | 
 |   last_decrypted_packet_level_ = level; | 
 |   last_packet_decrypted_ = true; | 
 |   if (level == ENCRYPTION_FORWARD_SECURE && | 
 |       !have_decrypted_first_one_rtt_packet_) { | 
 |     have_decrypted_first_one_rtt_packet_ = true; | 
 |     if (version().UsesTls() && perspective_ == Perspective::IS_SERVER) { | 
 |       // Servers MAY temporarily retain 0-RTT keys to allow decrypting reordered | 
 |       // packets without requiring their contents to be retransmitted with 1-RTT | 
 |       // keys. After receiving a 1-RTT packet, servers MUST discard 0-RTT keys | 
 |       // within a short time; the RECOMMENDED time period is three times the | 
 |       // Probe Timeout. | 
 |       // https://quicwg.org/base-drafts/draft-ietf-quic-tls.html#name-discarding-0-rtt-keys | 
 |       discard_zero_rtt_decryption_keys_alarm_->Set( | 
 |           clock_->ApproximateNow() + sent_packet_manager_.GetPtoDelay() * 3); | 
 |     } | 
 |   } | 
 |   if (EnforceAntiAmplificationLimit() && !IsHandshakeConfirmed() && | 
 |       (last_decrypted_packet_level_ == ENCRYPTION_HANDSHAKE || | 
 |        last_decrypted_packet_level_ == ENCRYPTION_FORWARD_SECURE)) { | 
 |     // Address is validated by successfully processing a HANDSHAKE or 1-RTT | 
 |     // packet. | 
 |     default_path_.validated = true; | 
 |     stats_.address_validated_via_decrypting_packet = true; | 
 |   } | 
 |   idle_network_detector_.OnPacketReceived( | 
 |       last_received_packet_info_.receipt_time); | 
 |  | 
 |   visitor_->OnPacketDecrypted(level); | 
 | } | 
 |  | 
 | QuicSocketAddress QuicConnection::GetEffectivePeerAddressFromCurrentPacket() | 
 |     const { | 
 |   // By default, the connection is not proxied, and the effective peer address | 
 |   // is the packet's source address, i.e. the direct peer address. | 
 |   return last_received_packet_info_.source_address; | 
 | } | 
 |  | 
 | bool QuicConnection::OnPacketHeader(const QuicPacketHeader& header) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPacketHeader(header, clock_->ApproximateNow(), | 
 |                                    last_decrypted_packet_level_); | 
 |   } | 
 |  | 
 |   // Will be decremented below if we fall through to return true. | 
 |   ++stats_.packets_dropped; | 
 |  | 
 |   if (!ProcessValidatedPacket(header)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   // Initialize the current packet content state. | 
 |   most_recent_frame_type_ = NUM_FRAME_TYPES; | 
 |   current_packet_content_ = NO_FRAMES_RECEIVED; | 
 |   is_current_packet_connectivity_probing_ = false; | 
 |   has_path_challenge_in_current_packet_ = false; | 
 |   current_effective_peer_migration_type_ = NO_CHANGE; | 
 |  | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     if (!GetLargestReceivedPacket().IsInitialized() || | 
 |         header.packet_number > GetLargestReceivedPacket()) { | 
 |       // Update direct_peer_address_ and default path peer_address immediately | 
 |       // for client connections. | 
 |       // TODO(fayang): only change peer addresses in application data packet | 
 |       // number space. | 
 |       UpdatePeerAddress(last_received_packet_info_.source_address); | 
 |       default_path_.peer_address = GetEffectivePeerAddressFromCurrentPacket(); | 
 |     } | 
 |   } else { | 
 |     // At server, remember the address change type of effective_peer_address | 
 |     // in current_effective_peer_migration_type_. But this variable alone | 
 |     // doesn't necessarily starts a migration. A migration will be started | 
 |     // later, once the current packet is confirmed to meet the following | 
 |     // conditions: | 
 |     // 1) current_effective_peer_migration_type_ is not NO_CHANGE. | 
 |     // 2) The current packet is not a connectivity probing. | 
 |     // 3) The current packet is not reordered, i.e. its packet number is the | 
 |     //    largest of this connection so far. | 
 |     // Once the above conditions are confirmed, a new migration will start | 
 |     // even if there is an active migration underway. | 
 |     current_effective_peer_migration_type_ = | 
 |         QuicUtils::DetermineAddressChangeType( | 
 |             default_path_.peer_address, | 
 |             GetEffectivePeerAddressFromCurrentPacket()); | 
 |  | 
 |     if (connection_migration_use_new_cid_) { | 
 |       auto effective_peer_address = GetEffectivePeerAddressFromCurrentPacket(); | 
 |       // Since server does not send new connection ID to client before handshake | 
 |       // completion and source connection ID is omitted in short header packet, | 
 |       // the server_connection_id on PathState on the server side does not | 
 |       // affect the packets server writes after handshake completion. On the | 
 |       // other hand, it is still desirable to have the "correct" server | 
 |       // connection ID set on path. | 
 |       // 1) If client uses 1 unique server connection ID per path and the packet | 
 |       // is received from an existing path, then | 
 |       // last_packet_destination_connection_id_ will always be the same as the | 
 |       // server connection ID on path. Server side will maintain the 1-to-1 | 
 |       // mapping from server connection ID to path. | 
 |       // 2) If client uses multiple server connection IDs on the same path, | 
 |       // compared to the server_connection_id on path, | 
 |       // last_packet_destination_connection_id_ has the advantage that it is | 
 |       // still present in the session map since the packet can be routed here | 
 |       // regardless of packet reordering. | 
 |       if (IsDefaultPath(last_received_packet_info_.destination_address, | 
 |                         effective_peer_address)) { | 
 |         default_path_.server_connection_id = | 
 |             last_packet_destination_connection_id_; | 
 |       } else if (IsAlternativePath( | 
 |                      last_received_packet_info_.destination_address, | 
 |                      effective_peer_address)) { | 
 |         alternative_path_.server_connection_id = | 
 |             last_packet_destination_connection_id_; | 
 |       } | 
 |     } | 
 |  | 
 |     if (last_packet_destination_connection_id_ != | 
 |             default_path_.server_connection_id && | 
 |         (!original_destination_connection_id_.has_value() || | 
 |          last_packet_destination_connection_id_ != | 
 |              *original_destination_connection_id_)) { | 
 |       QUIC_CODE_COUNT(quic_connection_id_change); | 
 |     } | 
 |  | 
 |     QUIC_DLOG_IF(INFO, current_effective_peer_migration_type_ != NO_CHANGE) | 
 |         << ENDPOINT << "Effective peer's ip:port changed from " | 
 |         << default_path_.peer_address.ToString() << " to " | 
 |         << GetEffectivePeerAddressFromCurrentPacket().ToString() | 
 |         << ", active_effective_peer_migration_type is " | 
 |         << active_effective_peer_migration_type_; | 
 |   } | 
 |  | 
 |   --stats_.packets_dropped; | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Received packet header: " << header; | 
 |   last_header_ = header; | 
 |   if (!stats_.first_decrypted_packet.IsInitialized()) { | 
 |     stats_.first_decrypted_packet = last_header_.packet_number; | 
 |   } | 
 |  | 
 |   // Record packet receipt to populate ack info before processing stream | 
 |   // frames, since the processing may result in sending a bundled ack. | 
 |   QuicTime receipt_time = idle_network_detector_.time_of_last_received_packet(); | 
 |   if (reset_per_packet_state_for_undecryptable_packets_ && | 
 |       SupportsMultiplePacketNumberSpaces()) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N( | 
 |         quic_reset_per_packet_state_for_undecryptable_packets, 2, 2); | 
 |     receipt_time = last_received_packet_info_.receipt_time; | 
 |   } | 
 |   uber_received_packet_manager_.RecordPacketReceived( | 
 |       last_decrypted_packet_level_, last_header_, receipt_time); | 
 |   if (EnforceAntiAmplificationLimit() && !IsHandshakeConfirmed() && | 
 |       !header.retry_token.empty() && | 
 |       visitor_->ValidateToken(header.retry_token)) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Address validated via token."; | 
 |     QUIC_CODE_COUNT(quic_address_validated_via_token); | 
 |     default_path_.validated = true; | 
 |     stats_.address_validated_via_token = true; | 
 |   } | 
 |   QUICHE_DCHECK(connected_); | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnStreamFrame(const QuicStreamFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_3, !connected_) | 
 |       << "Processing STREAM frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a stream frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(STREAM_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnStreamFrame(frame); | 
 |   } | 
 |   if (!QuicUtils::IsCryptoStreamId(transport_version(), frame.stream_id) && | 
 |       last_decrypted_packet_level_ == ENCRYPTION_INITIAL) { | 
 |     if (MaybeConsiderAsMemoryCorruption(frame)) { | 
 |       CloseConnection(QUIC_MAYBE_CORRUPTED_MEMORY, | 
 |                       "Received crypto frame on non crypto stream.", | 
 |                       ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |       return false; | 
 |     } | 
 |  | 
 |     QUIC_PEER_BUG(quic_peer_bug_10511_6) | 
 |         << ENDPOINT << "Received an unencrypted data frame: closing connection" | 
 |         << " packet_number:" << last_header_.packet_number | 
 |         << " stream_id:" << frame.stream_id | 
 |         << " received_packets:" << ack_frame(); | 
 |     CloseConnection(QUIC_UNENCRYPTED_STREAM_DATA, | 
 |                     "Unencrypted stream data seen.", | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |   // TODO(fayang): Consider moving UpdatePacketContent and | 
 |   // MaybeUpdateAckTimeout to a stand-alone function instead of calling them for | 
 |   // all frames. | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnStreamFrame(frame); | 
 |   stats_.stream_bytes_received += frame.data_length; | 
 |   consecutive_retransmittable_on_wire_ping_count_ = 0; | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnCryptoFrame(const QuicCryptoFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_4, !connected_) | 
 |       << "Processing CRYPTO frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a CRYPTO frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(CRYPTO_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnCryptoFrame(frame); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnCryptoFrame(frame); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnAckFrameStart(QuicPacketNumber largest_acked, | 
 |                                      QuicTime::Delta ack_delay_time) { | 
 |   QUIC_BUG_IF(quic_bug_12714_5, !connected_) | 
 |       << "Processing ACK frame start when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   if (processing_ack_frame_) { | 
 |     CloseConnection(QUIC_INVALID_ACK_DATA, | 
 |                     "Received a new ack while processing an ack frame.", | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |  | 
 |   // Since an ack frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(ACK_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   QUIC_DVLOG(1) << ENDPOINT | 
 |                 << "OnAckFrameStart, largest_acked: " << largest_acked; | 
 |  | 
 |   if (GetLargestReceivedPacketWithAck().IsInitialized() && | 
 |       last_header_.packet_number <= GetLargestReceivedPacketWithAck()) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Received an old ack frame: ignoring"; | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (!sent_packet_manager_.GetLargestSentPacket().IsInitialized() || | 
 |       largest_acked > sent_packet_manager_.GetLargestSentPacket()) { | 
 |     QUIC_DLOG(WARNING) << ENDPOINT | 
 |                        << "Peer's observed unsent packet:" << largest_acked | 
 |                        << " vs " << sent_packet_manager_.GetLargestSentPacket() | 
 |                        << ". SupportsMultiplePacketNumberSpaces():" | 
 |                        << SupportsMultiplePacketNumberSpaces() | 
 |                        << ", last_decrypted_packet_level_:" | 
 |                        << last_decrypted_packet_level_; | 
 |     // We got an ack for data we have not sent. | 
 |     CloseConnection(QUIC_INVALID_ACK_DATA, "Largest observed too high.", | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |   processing_ack_frame_ = true; | 
 |   sent_packet_manager_.OnAckFrameStart( | 
 |       largest_acked, ack_delay_time, | 
 |       idle_network_detector_.time_of_last_received_packet()); | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnAckRange(QuicPacketNumber start, QuicPacketNumber end) { | 
 |   QUIC_BUG_IF(quic_bug_12714_6, !connected_) | 
 |       << "Processing ACK frame range when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   QUIC_DVLOG(1) << ENDPOINT << "OnAckRange: [" << start << ", " << end << ")"; | 
 |  | 
 |   if (GetLargestReceivedPacketWithAck().IsInitialized() && | 
 |       last_header_.packet_number <= GetLargestReceivedPacketWithAck()) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Received an old ack frame: ignoring"; | 
 |     return true; | 
 |   } | 
 |  | 
 |   sent_packet_manager_.OnAckRange(start, end); | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnAckTimestamp(QuicPacketNumber packet_number, | 
 |                                     QuicTime timestamp) { | 
 |   QUIC_BUG_IF(quic_bug_10511_7, !connected_) | 
 |       << "Processing ACK frame time stamp when connection " | 
 |          "is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   QUIC_DVLOG(1) << ENDPOINT << "OnAckTimestamp: [" << packet_number << ", " | 
 |                 << timestamp.ToDebuggingValue() << ")"; | 
 |  | 
 |   if (GetLargestReceivedPacketWithAck().IsInitialized() && | 
 |       last_header_.packet_number <= GetLargestReceivedPacketWithAck()) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Received an old ack frame: ignoring"; | 
 |     return true; | 
 |   } | 
 |  | 
 |   sent_packet_manager_.OnAckTimestamp(packet_number, timestamp); | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnAckFrameEnd(QuicPacketNumber start) { | 
 |   QUIC_BUG_IF(quic_bug_12714_7, !connected_) | 
 |       << "Processing ACK frame end when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   QUIC_DVLOG(1) << ENDPOINT << "OnAckFrameEnd, start: " << start; | 
 |  | 
 |   if (GetLargestReceivedPacketWithAck().IsInitialized() && | 
 |       last_header_.packet_number <= GetLargestReceivedPacketWithAck()) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Received an old ack frame: ignoring"; | 
 |     return true; | 
 |   } | 
 |   const bool one_rtt_packet_was_acked = | 
 |       sent_packet_manager_.one_rtt_packet_acked(); | 
 |   const bool zero_rtt_packet_was_acked = | 
 |       sent_packet_manager_.zero_rtt_packet_acked(); | 
 |   const AckResult ack_result = sent_packet_manager_.OnAckFrameEnd( | 
 |       idle_network_detector_.time_of_last_received_packet(), | 
 |       last_header_.packet_number, last_decrypted_packet_level_); | 
 |   if (ack_result != PACKETS_NEWLY_ACKED && | 
 |       ack_result != NO_PACKETS_NEWLY_ACKED) { | 
 |     // Error occurred (e.g., this ACK tries to ack packets in wrong packet | 
 |     // number space), and this would cause the connection to be closed. | 
 |     QUIC_DLOG(ERROR) << ENDPOINT | 
 |                      << "Error occurred when processing an ACK frame: " | 
 |                      << QuicUtils::AckResultToString(ack_result); | 
 |     return false; | 
 |   } | 
 |   if (SupportsMultiplePacketNumberSpaces() && !one_rtt_packet_was_acked && | 
 |       sent_packet_manager_.one_rtt_packet_acked()) { | 
 |     visitor_->OnOneRttPacketAcknowledged(); | 
 |   } | 
 |   if (debug_visitor_ != nullptr && version().UsesTls() && | 
 |       !zero_rtt_packet_was_acked && | 
 |       sent_packet_manager_.zero_rtt_packet_acked()) { | 
 |     debug_visitor_->OnZeroRttPacketAcked(); | 
 |   } | 
 |   // Cancel the send alarm because new packets likely have been acked, which | 
 |   // may change the congestion window and/or pacing rate.  Canceling the alarm | 
 |   // causes CanWrite to recalculate the next send time. | 
 |   if (send_alarm_->IsSet()) { | 
 |     send_alarm_->Cancel(); | 
 |   } | 
 |   if (supports_release_time_) { | 
 |     // Update pace time into future because smoothed RTT is likely updated. | 
 |     UpdateReleaseTimeIntoFuture(); | 
 |   } | 
 |   SetLargestReceivedPacketWithAck(last_header_.packet_number); | 
 |   // If the incoming ack's packets set expresses missing packets: peer is still | 
 |   // waiting for a packet lower than a packet that we are no longer planning to | 
 |   // send. | 
 |   // If the incoming ack's packets set expresses received packets: peer is still | 
 |   // acking packets which we never care about. | 
 |   // Send an ack to raise the high water mark. | 
 |   const bool send_stop_waiting = | 
 |       no_stop_waiting_frames_ ? false : GetLeastUnacked() > start; | 
 |   PostProcessAfterAckFrame(send_stop_waiting, | 
 |                            ack_result == PACKETS_NEWLY_ACKED); | 
 |   processing_ack_frame_ = false; | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnStopWaitingFrame(const QuicStopWaitingFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_8, !connected_) | 
 |       << "Processing STOP_WAITING frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a stop waiting frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(STOP_WAITING_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (no_stop_waiting_frames_) { | 
 |     return true; | 
 |   } | 
 |   if (largest_seen_packet_with_stop_waiting_.IsInitialized() && | 
 |       last_header_.packet_number <= largest_seen_packet_with_stop_waiting_) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT | 
 |                     << "Received an old stop waiting frame: ignoring"; | 
 |     return true; | 
 |   } | 
 |  | 
 |   const char* error = ValidateStopWaitingFrame(frame); | 
 |   if (error != nullptr) { | 
 |     CloseConnection(QUIC_INVALID_STOP_WAITING_DATA, error, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnStopWaitingFrame(frame); | 
 |   } | 
 |  | 
 |   largest_seen_packet_with_stop_waiting_ = last_header_.packet_number; | 
 |   uber_received_packet_manager_.DontWaitForPacketsBefore( | 
 |       last_decrypted_packet_level_, frame.least_unacked); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnPaddingFrame(const QuicPaddingFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_9, !connected_) | 
 |       << "Processing PADDING frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (!UpdatePacketContent(PADDING_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPaddingFrame(frame); | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnPingFrame(const QuicPingFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_10, !connected_) | 
 |       << "Processing PING frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (!UpdatePacketContent(PING_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     QuicTime::Delta ping_received_delay = QuicTime::Delta::Zero(); | 
 |     const QuicTime now = clock_->ApproximateNow(); | 
 |     if (now > stats_.connection_creation_time) { | 
 |       ping_received_delay = now - stats_.connection_creation_time; | 
 |     } | 
 |     debug_visitor_->OnPingFrame(frame, ping_received_delay); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   return true; | 
 | } | 
 |  | 
 | const char* QuicConnection::ValidateStopWaitingFrame( | 
 |     const QuicStopWaitingFrame& stop_waiting) { | 
 |   const QuicPacketNumber peer_least_packet_awaiting_ack = | 
 |       uber_received_packet_manager_.peer_least_packet_awaiting_ack(); | 
 |   if (peer_least_packet_awaiting_ack.IsInitialized() && | 
 |       stop_waiting.least_unacked < peer_least_packet_awaiting_ack) { | 
 |     QUIC_DLOG(ERROR) << ENDPOINT << "Peer's sent low least_unacked: " | 
 |                      << stop_waiting.least_unacked << " vs " | 
 |                      << peer_least_packet_awaiting_ack; | 
 |     // We never process old ack frames, so this number should only increase. | 
 |     return "Least unacked too small."; | 
 |   } | 
 |  | 
 |   if (stop_waiting.least_unacked > last_header_.packet_number) { | 
 |     QUIC_DLOG(ERROR) << ENDPOINT | 
 |                      << "Peer sent least_unacked:" << stop_waiting.least_unacked | 
 |                      << " greater than the enclosing packet number:" | 
 |                      << last_header_.packet_number; | 
 |     return "Least unacked too large."; | 
 |   } | 
 |  | 
 |   return nullptr; | 
 | } | 
 |  | 
 | bool QuicConnection::OnRstStreamFrame(const QuicRstStreamFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_11, !connected_) | 
 |       << "Processing RST_STREAM frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a reset stream frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(RST_STREAM_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnRstStreamFrame(frame); | 
 |   } | 
 |   QUIC_DLOG(INFO) << ENDPOINT | 
 |                   << "RST_STREAM_FRAME received for stream: " << frame.stream_id | 
 |                   << " with error: " | 
 |                   << QuicRstStreamErrorCodeToString(frame.error_code); | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnRstStream(frame); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnStopSendingFrame(const QuicStopSendingFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_12, !connected_) | 
 |       << "Processing STOP_SENDING frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a reset stream frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(STOP_SENDING_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnStopSendingFrame(frame); | 
 |   } | 
 |  | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "STOP_SENDING frame received for stream: " | 
 |                   << frame.stream_id | 
 |                   << " with error: " << frame.ietf_error_code; | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnStopSendingFrame(frame); | 
 |   return connected_; | 
 | } | 
 |  | 
 | class ReversePathValidationContext : public QuicPathValidationContext { | 
 |  public: | 
 |   ReversePathValidationContext(const QuicSocketAddress& self_address, | 
 |                                const QuicSocketAddress& peer_address, | 
 |                                const QuicSocketAddress& effective_peer_address, | 
 |                                QuicConnection* connection) | 
 |       : QuicPathValidationContext(self_address, | 
 |                                   peer_address, | 
 |                                   effective_peer_address), | 
 |         connection_(connection) {} | 
 |  | 
 |   QuicPacketWriter* WriterToUse() override { return connection_->writer(); } | 
 |  | 
 |  private: | 
 |   QuicConnection* connection_; | 
 | }; | 
 |  | 
 | bool QuicConnection::OnPathChallengeFrame(const QuicPathChallengeFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_10511_8, !connected_) | 
 |       << "Processing PATH_CHALLENGE frame when connection " | 
 |          "is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (has_path_challenge_in_current_packet_) { | 
 |     QUICHE_DCHECK(send_path_response_); | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_send_path_response2, 2, 5); | 
 |     // Only respond to the 1st PATH_CHALLENGE in the packet. | 
 |     return true; | 
 |   } | 
 |   if (!validate_client_addresses_) { | 
 |     return OnPathChallengeFrameInternal(frame); | 
 |   } | 
 |   QUIC_CODE_COUNT_N(quic_server_reverse_validate_new_path3, 1, 6); | 
 |   { | 
 |     // TODO(danzh) inline OnPathChallengeFrameInternal() once | 
 |     // validate_client_addresses_ is deprecated. | 
 |     if (!OnPathChallengeFrameInternal(frame)) { | 
 |       return false; | 
 |     } | 
 |   } | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnPathChallengeFrameInternal( | 
 |     const QuicPathChallengeFrame& frame) { | 
 |   should_proactively_validate_peer_address_on_path_challenge_ = false; | 
 |   // UpdatePacketContent() may start reverse path validation. | 
 |   if (!UpdatePacketContent(PATH_CHALLENGE_FRAME)) { | 
 |     return false; | 
 |   } | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPathChallengeFrame(frame); | 
 |   } | 
 |  | 
 |   const QuicSocketAddress current_effective_peer_address = | 
 |       GetEffectivePeerAddressFromCurrentPacket(); | 
 |   QuicConnectionId client_cid, server_cid; | 
 |   FindOnPathConnectionIds(last_received_packet_info_.destination_address, | 
 |                           current_effective_peer_address, &client_cid, | 
 |                           &server_cid); | 
 |   QuicPacketCreator::ScopedPeerAddressContext context( | 
 |       &packet_creator_, last_received_packet_info_.source_address, client_cid, | 
 |       server_cid, connection_migration_use_new_cid_); | 
 |   if (should_proactively_validate_peer_address_on_path_challenge_) { | 
 |     // Conditions to proactively validate peer address: | 
 |     // The perspective is server | 
 |     // The PATH_CHALLENGE is received on an unvalidated alternative path. | 
 |     // The connection isn't validating migrated peer address, which is of | 
 |     // higher prority. | 
 |     QUIC_DVLOG(1) << "Proactively validate the effective peer address " | 
 |                   << current_effective_peer_address; | 
 |     QUIC_CODE_COUNT_N(quic_kick_off_client_address_validation, 2, 6); | 
 |     ValidatePath(std::make_unique<ReversePathValidationContext>( | 
 |                      default_path_.self_address, | 
 |                      last_received_packet_info_.source_address, | 
 |                      current_effective_peer_address, this), | 
 |                  std::make_unique<ReversePathValidationResultDelegate>( | 
 |                      this, peer_address())); | 
 |   } | 
 |   if (!send_path_response_) { | 
 |     // Save the path challenge's payload, for later use in generating the | 
 |     // response. | 
 |     received_path_challenge_payloads_.push_back(frame.data_buffer); | 
 |  | 
 |     MaybeUpdateAckTimeout(); | 
 |     return true; | 
 |   } | 
 |   QUIC_RELOADABLE_FLAG_COUNT_N(quic_send_path_response2, 3, 5); | 
 |   has_path_challenge_in_current_packet_ = true; | 
 |   MaybeUpdateAckTimeout(); | 
 |   // Queue or send PATH_RESPONSE. Send PATH_RESPONSE to the source address of | 
 |   // the current incoming packet, even if it's not the default path or the | 
 |   // alternative path. | 
 |   const bool success = SendPathResponse( | 
 |       frame.data_buffer, last_received_packet_info_.source_address, | 
 |       current_effective_peer_address); | 
 |   if (GetQuicReloadableFlag(quic_drop_unsent_path_response)) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT(quic_drop_unsent_path_response); | 
 |   } | 
 |   if (!success) { | 
 |     QUIC_CODE_COUNT(quic_failed_to_send_path_response); | 
 |     if (!GetQuicReloadableFlag(quic_drop_unsent_path_response)) { | 
 |       // Queue the payloads to re-try later. | 
 |       pending_path_challenge_payloads_.push_back( | 
 |           {frame.data_buffer, last_received_packet_info_.source_address}); | 
 |     } | 
 |   } | 
 |   // TODO(b/150095588): change the stats to | 
 |   // num_valid_path_challenge_received. | 
 |   ++stats_.num_connectivity_probing_received; | 
 |  | 
 |   // SendPathResponse() might cause connection to be closed. | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnPathResponseFrame(const QuicPathResponseFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_10511_9, !connected_) | 
 |       << "Processing PATH_RESPONSE frame when connection " | 
 |          "is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (!UpdatePacketContent(PATH_RESPONSE_FRAME)) { | 
 |     return false; | 
 |   } | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPathResponseFrame(frame); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   if (use_path_validator_) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_pass_path_response_to_validator, 1, 4); | 
 |     path_validator_.OnPathResponse( | 
 |         frame.data_buffer, last_received_packet_info_.destination_address); | 
 |   } else { | 
 |     if (!transmitted_connectivity_probe_payload_ || | 
 |         *transmitted_connectivity_probe_payload_ != frame.data_buffer) { | 
 |       // Is not for the probe we sent, ignore it. | 
 |       return true; | 
 |     } | 
 |     // Have received the matching PATH RESPONSE, saved payload no longer valid. | 
 |     transmitted_connectivity_probe_payload_ = nullptr; | 
 |   } | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnConnectionCloseFrame( | 
 |     const QuicConnectionCloseFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_10511_10, !connected_) | 
 |       << "Processing CONNECTION_CLOSE frame when " | 
 |          "connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a connection close frame was received, this is not a connectivity | 
 |   // probe. A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(CONNECTION_CLOSE_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnConnectionCloseFrame(frame); | 
 |   } | 
 |   switch (frame.close_type) { | 
 |     case GOOGLE_QUIC_CONNECTION_CLOSE: | 
 |       QUIC_DLOG(INFO) << ENDPOINT << "Received ConnectionClose for connection: " | 
 |                       << connection_id() << ", with error: " | 
 |                       << QuicErrorCodeToString(frame.quic_error_code) << " (" | 
 |                       << frame.error_details << ")"; | 
 |       break; | 
 |     case IETF_QUIC_TRANSPORT_CONNECTION_CLOSE: | 
 |       QUIC_DLOG(INFO) << ENDPOINT | 
 |                       << "Received Transport ConnectionClose for connection: " | 
 |                       << connection_id() << ", with error: " | 
 |                       << QuicErrorCodeToString(frame.quic_error_code) << " (" | 
 |                       << frame.error_details << ")" | 
 |                       << ", transport error code: " | 
 |                       << QuicIetfTransportErrorCodeString( | 
 |                              static_cast<QuicIetfTransportErrorCodes>( | 
 |                                  frame.wire_error_code)) | 
 |                       << ", error frame type: " | 
 |                       << frame.transport_close_frame_type; | 
 |       break; | 
 |     case IETF_QUIC_APPLICATION_CONNECTION_CLOSE: | 
 |       QUIC_DLOG(INFO) << ENDPOINT | 
 |                       << "Received Application ConnectionClose for connection: " | 
 |                       << connection_id() << ", with error: " | 
 |                       << QuicErrorCodeToString(frame.quic_error_code) << " (" | 
 |                       << frame.error_details << ")" | 
 |                       << ", application error code: " << frame.wire_error_code; | 
 |       break; | 
 |   } | 
 |  | 
 |   if (frame.quic_error_code == QUIC_BAD_MULTIPATH_FLAG) { | 
 |     QUIC_LOG_FIRST_N(ERROR, 10) << "Unexpected QUIC_BAD_MULTIPATH_FLAG error." | 
 |                                 << " last_received_header: " << last_header_ | 
 |                                 << " encryption_level: " << encryption_level_; | 
 |   } | 
 |   TearDownLocalConnectionState(frame, ConnectionCloseSource::FROM_PEER); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnMaxStreamsFrame(const QuicMaxStreamsFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_13, !connected_) | 
 |       << "Processing MAX_STREAMS frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (!UpdatePacketContent(MAX_STREAMS_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnMaxStreamsFrame(frame); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   return visitor_->OnMaxStreamsFrame(frame) && connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnStreamsBlockedFrame( | 
 |     const QuicStreamsBlockedFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_10511_11, !connected_) | 
 |       << "Processing STREAMS_BLOCKED frame when " | 
 |          "connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (!UpdatePacketContent(STREAMS_BLOCKED_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnStreamsBlockedFrame(frame); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   return visitor_->OnStreamsBlockedFrame(frame) && connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnGoAwayFrame(const QuicGoAwayFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_14, !connected_) | 
 |       << "Processing GOAWAY frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a go away frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(GOAWAY_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnGoAwayFrame(frame); | 
 |   } | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "GOAWAY_FRAME received with last good stream: " | 
 |                   << frame.last_good_stream_id | 
 |                   << " and error: " << QuicErrorCodeToString(frame.error_code) | 
 |                   << " and reason: " << frame.reason_phrase; | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnGoAway(frame); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_10511_12, !connected_) | 
 |       << "Processing WINDOW_UPDATE frame when connection " | 
 |          "is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a window update frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(WINDOW_UPDATE_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnWindowUpdateFrame( | 
 |         frame, idle_network_detector_.time_of_last_received_packet()); | 
 |   } | 
 |   QUIC_DVLOG(1) << ENDPOINT << "WINDOW_UPDATE_FRAME received " << frame; | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnWindowUpdateFrame(frame); | 
 |   return connected_; | 
 | } | 
 |  | 
 | void QuicConnection::OnClientConnectionIdAvailable() { | 
 |   QUICHE_DCHECK(perspective_ == Perspective::IS_SERVER); | 
 |   if (!peer_issued_cid_manager_->HasUnusedConnectionId()) { | 
 |     return; | 
 |   } | 
 |   if (default_path_.client_connection_id.IsEmpty()) { | 
 |     // Count client connection ID patched onto the default path. | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_connection_migration_use_new_cid_v2, 3, | 
 |                                  6); | 
 |     const QuicConnectionIdData* unused_cid_data = | 
 |         peer_issued_cid_manager_->ConsumeOneUnusedConnectionId(); | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Patch connection ID " | 
 |                   << unused_cid_data->connection_id << " to default path"; | 
 |     default_path_.client_connection_id = unused_cid_data->connection_id; | 
 |     default_path_.stateless_reset_token = | 
 |         unused_cid_data->stateless_reset_token; | 
 |     QUICHE_DCHECK(!packet_creator_.HasPendingFrames()); | 
 |     QUICHE_DCHECK(packet_creator_.GetDestinationConnectionId().IsEmpty()); | 
 |     packet_creator_.SetClientConnectionId(default_path_.client_connection_id); | 
 |     return; | 
 |   } | 
 |   if (alternative_path_.peer_address.IsInitialized() && | 
 |       alternative_path_.client_connection_id.IsEmpty()) { | 
 |     // Count client connection ID patched onto the alternative path. | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_connection_migration_use_new_cid_v2, 4, | 
 |                                  6); | 
 |     const QuicConnectionIdData* unused_cid_data = | 
 |         peer_issued_cid_manager_->ConsumeOneUnusedConnectionId(); | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Patch connection ID " | 
 |                   << unused_cid_data->connection_id << " to alternative path"; | 
 |     alternative_path_.client_connection_id = unused_cid_data->connection_id; | 
 |     alternative_path_.stateless_reset_token = | 
 |         unused_cid_data->stateless_reset_token; | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::ShouldSetRetransmissionAlarmOnPacketSent( | 
 |     bool in_flight, EncryptionLevel level) const { | 
 |   if (!retransmission_alarm_->IsSet()) { | 
 |     return true; | 
 |   } | 
 |   if (!in_flight) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (!SupportsMultiplePacketNumberSpaces()) { | 
 |     return true; | 
 |   } | 
 |   // Before handshake gets confirmed, do not re-arm PTO timer on application | 
 |   // data. Think about this scenario: on the client side, the CHLO gets | 
 |   // acknowledged and the SHLO is not received yet. The PTO alarm is set when | 
 |   // the CHLO acknowledge is received (and there is no in flight INITIAL | 
 |   // packet). Re-arming PTO alarm on 0-RTT packet would keep postponing the PTO | 
 |   // alarm. | 
 |   return IsHandshakeConfirmed() || level == ENCRYPTION_INITIAL || | 
 |          level == ENCRYPTION_HANDSHAKE; | 
 | } | 
 |  | 
 | bool QuicConnection::OnNewConnectionIdFrameInner( | 
 |     const QuicNewConnectionIdFrame& frame) { | 
 |   if (peer_issued_cid_manager_ == nullptr) { | 
 |     CloseConnection( | 
 |         IETF_QUIC_PROTOCOL_VIOLATION, | 
 |         "Receives NEW_CONNECTION_ID while peer uses zero length connection ID", | 
 |         ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |   std::string error_detail; | 
 |   QuicErrorCode error = | 
 |       peer_issued_cid_manager_->OnNewConnectionIdFrame(frame, &error_detail); | 
 |   if (error != QUIC_NO_ERROR) { | 
 |     CloseConnection(error, error_detail, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |   if (perspective_ == Perspective::IS_SERVER) { | 
 |     OnClientConnectionIdAvailable(); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnNewConnectionIdFrame( | 
 |     const QuicNewConnectionIdFrame& frame) { | 
 |   QUICHE_DCHECK(version().HasIetfQuicFrames()); | 
 |   QUIC_BUG_IF(quic_bug_10511_13, !connected_) | 
 |       << "Processing NEW_CONNECTION_ID frame when " | 
 |          "connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (!UpdatePacketContent(NEW_CONNECTION_ID_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnNewConnectionIdFrame(frame); | 
 |   } | 
 |   return OnNewConnectionIdFrameInner(frame); | 
 | } | 
 |  | 
 | bool QuicConnection::OnRetireConnectionIdFrame( | 
 |     const QuicRetireConnectionIdFrame& frame) { | 
 |   QUICHE_DCHECK(version().HasIetfQuicFrames()); | 
 |   QUIC_BUG_IF(quic_bug_10511_14, !connected_) | 
 |       << "Processing RETIRE_CONNECTION_ID frame when " | 
 |          "connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (!UpdatePacketContent(RETIRE_CONNECTION_ID_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnRetireConnectionIdFrame(frame); | 
 |   } | 
 |   if (!connection_migration_use_new_cid_) { | 
 |     // Do not respond to RetireConnectionId frame. | 
 |     return true; | 
 |   } | 
 |   if (self_issued_cid_manager_ == nullptr) { | 
 |     CloseConnection( | 
 |         IETF_QUIC_PROTOCOL_VIOLATION, | 
 |         "Receives RETIRE_CONNECTION_ID while new connection ID is never issued", | 
 |         ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |   std::string error_detail; | 
 |   QuicErrorCode error = self_issued_cid_manager_->OnRetireConnectionIdFrame( | 
 |       frame, sent_packet_manager_.GetPtoDelay(), &error_detail); | 
 |   if (error != QUIC_NO_ERROR) { | 
 |     CloseConnection(error, error_detail, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |   // Count successfully received RETIRE_CONNECTION_ID frames. | 
 |   QUIC_RELOADABLE_FLAG_COUNT_N(quic_connection_migration_use_new_cid_v2, 5, 6); | 
 |   MaybeUpdateAckTimeout(); | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnNewTokenFrame(const QuicNewTokenFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_15, !connected_) | 
 |       << "Processing NEW_TOKEN frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (!UpdatePacketContent(NEW_TOKEN_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnNewTokenFrame(frame); | 
 |   } | 
 |   if (perspective_ == Perspective::IS_SERVER) { | 
 |     CloseConnection(QUIC_INVALID_NEW_TOKEN, "Server received new token frame.", | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |   // NEW_TOKEN frame should insitgate ACKs. | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnNewTokenReceived(frame.token); | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnMessageFrame(const QuicMessageFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_16, !connected_) | 
 |       << "Processing MESSAGE frame when connection is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a message frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(MESSAGE_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnMessageFrame(frame); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnMessageReceived( | 
 |       absl::string_view(frame.data, frame.message_length)); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnHandshakeDoneFrame(const QuicHandshakeDoneFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_10511_15, !connected_) | 
 |       << "Processing HANDSHAKE_DONE frame when connection " | 
 |          "is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (!version().UsesTls()) { | 
 |     CloseConnection(IETF_QUIC_PROTOCOL_VIOLATION, | 
 |                     "Handshake done frame is unsupported", | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (perspective_ == Perspective::IS_SERVER) { | 
 |     CloseConnection(IETF_QUIC_PROTOCOL_VIOLATION, | 
 |                     "Server received handshake done frame.", | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return false; | 
 |   } | 
 |  | 
 |   // Since a handshake done frame was received, this is not a connectivity | 
 |   // probe. A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(HANDSHAKE_DONE_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnHandshakeDoneFrame(frame); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnHandshakeDoneReceived(); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnAckFrequencyFrame(const QuicAckFrequencyFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_10511_16, !connected_) | 
 |       << "Processing ACK_FREQUENCY frame when connection " | 
 |          "is closed. Last frame: " | 
 |       << most_recent_frame_type_; | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnAckFrequencyFrame(frame); | 
 |   } | 
 |   if (!UpdatePacketContent(ACK_FREQUENCY_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (!can_receive_ack_frequency_frame_) { | 
 |     QUIC_LOG_EVERY_N_SEC(ERROR, 120) << "Get unexpected AckFrequencyFrame."; | 
 |     return false; | 
 |   } | 
 |   if (auto packet_number_space = | 
 |           QuicUtils::GetPacketNumberSpace(last_decrypted_packet_level_) == | 
 |           APPLICATION_DATA) { | 
 |     uber_received_packet_manager_.OnAckFrequencyFrame(frame); | 
 |   } else { | 
 |     QUIC_LOG_EVERY_N_SEC(ERROR, 120) | 
 |         << "Get AckFrequencyFrame in packet number space " | 
 |         << packet_number_space; | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnBlockedFrame(const QuicBlockedFrame& frame) { | 
 |   QUIC_BUG_IF(quic_bug_12714_17, !connected_) | 
 |       << "Processing BLOCKED frame when connection is closed. Last frame was " | 
 |       << most_recent_frame_type_; | 
 |  | 
 |   // Since a blocked frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   if (!UpdatePacketContent(BLOCKED_FRAME)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnBlockedFrame(frame); | 
 |   } | 
 |   QUIC_DLOG(INFO) << ENDPOINT | 
 |                   << "BLOCKED_FRAME received for stream: " << frame.stream_id; | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnBlockedFrame(frame); | 
 |   stats_.blocked_frames_received++; | 
 |   return connected_; | 
 | } | 
 |  | 
 | void QuicConnection::OnPacketComplete() { | 
 |   // Don't do anything if this packet closed the connection. | 
 |   if (!connected_) { | 
 |     ClearLastFrames(); | 
 |     return; | 
 |   } | 
 |  | 
 |   if (IsCurrentPacketConnectivityProbing()) { | 
 |     QUICHE_DCHECK(!version().HasIetfQuicFrames()); | 
 |     ++stats_.num_connectivity_probing_received; | 
 |   } | 
 |  | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Got" | 
 |                 << (SupportsMultiplePacketNumberSpaces() | 
 |                         ? (" " + EncryptionLevelToString( | 
 |                                      last_decrypted_packet_level_)) | 
 |                         : "") | 
 |                 << " packet " << last_header_.packet_number << " for " | 
 |                 << GetServerConnectionIdAsRecipient(last_header_, perspective_); | 
 |  | 
 |   QUIC_DLOG_IF(INFO, current_packet_content_ == SECOND_FRAME_IS_PADDING) | 
 |       << ENDPOINT << "Received a padded PING packet. is_probing: " | 
 |       << IsCurrentPacketConnectivityProbing(); | 
 |  | 
 |   MaybeRespondToConnectivityProbingOrMigration(); | 
 |  | 
 |   current_effective_peer_migration_type_ = NO_CHANGE; | 
 |  | 
 |   // For IETF QUIC, it is guaranteed that TLS will give connection the | 
 |   // corresponding write key before read key. In other words, connection should | 
 |   // never process a packet while an ACK for it cannot be encrypted. | 
 |   if (!should_last_packet_instigate_acks_) { | 
 |     uber_received_packet_manager_.MaybeUpdateAckTimeout( | 
 |         should_last_packet_instigate_acks_, last_decrypted_packet_level_, | 
 |         last_header_.packet_number, clock_->ApproximateNow(), | 
 |         sent_packet_manager_.GetRttStats()); | 
 |   } | 
 |  | 
 |   ClearLastFrames(); | 
 |   CloseIfTooManyOutstandingSentPackets(); | 
 | } | 
 |  | 
 | void QuicConnection::MaybeRespondToConnectivityProbingOrMigration() { | 
 |   if (version().HasIetfQuicFrames()) { | 
 |     if (send_path_response_) { | 
 |       return; | 
 |     } | 
 |     if (perspective_ == Perspective::IS_CLIENT) { | 
 |       // This node is a client, notify that a speculative connectivity probing | 
 |       // packet has been received anyway. | 
 |       visitor_->OnPacketReceived(last_received_packet_info_.destination_address, | 
 |                                  last_received_packet_info_.source_address, | 
 |                                  /*is_connectivity_probe=*/false); | 
 |       return; | 
 |     } | 
 |     if (!received_path_challenge_payloads_.empty()) { | 
 |       if (current_effective_peer_migration_type_ != NO_CHANGE) { | 
 |         // TODO(b/150095588): change the stats to | 
 |         // num_valid_path_challenge_received. | 
 |         ++stats_.num_connectivity_probing_received; | 
 |       } | 
 |       // If the packet contains PATH CHALLENGE, send appropriate RESPONSE. | 
 |       // There was at least one PATH CHALLENGE in the received packet, | 
 |       // Generate the required PATH RESPONSE. | 
 |       SendGenericPathProbePacket(nullptr, | 
 |                                  last_received_packet_info_.source_address, | 
 |                                  /* is_response=*/true); | 
 |       return; | 
 |     } | 
 |   } else { | 
 |     if (IsCurrentPacketConnectivityProbing()) { | 
 |       visitor_->OnPacketReceived(last_received_packet_info_.destination_address, | 
 |                                  last_received_packet_info_.source_address, | 
 |                                  /*is_connectivity_probe=*/true); | 
 |       return; | 
 |     } | 
 |     if (perspective_ == Perspective::IS_CLIENT) { | 
 |       // This node is a client, notify that a speculative connectivity probing | 
 |       // packet has been received anyway. | 
 |       QUIC_DVLOG(1) | 
 |           << ENDPOINT | 
 |           << "Received a speculative connectivity probing packet for " | 
 |           << GetServerConnectionIdAsRecipient(last_header_, perspective_) | 
 |           << " from ip:port: " | 
 |           << last_received_packet_info_.source_address.ToString() | 
 |           << " to ip:port: " | 
 |           << last_received_packet_info_.destination_address.ToString(); | 
 |       visitor_->OnPacketReceived(last_received_packet_info_.destination_address, | 
 |                                  last_received_packet_info_.source_address, | 
 |                                  /*is_connectivity_probe=*/false); | 
 |       return; | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::IsValidStatelessResetToken( | 
 |     const StatelessResetToken& token) const { | 
 |   QUICHE_DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |   return default_path_.stateless_reset_token.has_value() && | 
 |          QuicUtils::AreStatelessResetTokensEqual( | 
 |              token, *default_path_.stateless_reset_token); | 
 | } | 
 |  | 
 | void QuicConnection::OnAuthenticatedIetfStatelessResetPacket( | 
 |     const QuicIetfStatelessResetPacket& /*packet*/) { | 
 |   // TODO(fayang): Add OnAuthenticatedIetfStatelessResetPacket to | 
 |   // debug_visitor_. | 
 |   QUICHE_DCHECK(version().HasIetfInvariantHeader()); | 
 |   QUICHE_DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |  | 
 |   if (use_path_validator_) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_pass_path_response_to_validator, 4, 4); | 
 |     if (!IsDefaultPath(last_received_packet_info_.destination_address, | 
 |                        last_received_packet_info_.source_address)) { | 
 |       // This packet is received on a probing path. Do not close connection. | 
 |       if (IsAlternativePath(last_received_packet_info_.destination_address, | 
 |                             GetEffectivePeerAddressFromCurrentPacket())) { | 
 |         QUIC_BUG_IF(quic_bug_12714_18, alternative_path_.validated) | 
 |             << "STATELESS_RESET received on alternate path after it's " | 
 |                "validated."; | 
 |         path_validator_.CancelPathValidation(); | 
 |       } else { | 
 |         QUIC_BUG(quic_bug_10511_17) | 
 |             << "Received Stateless Reset on unknown socket."; | 
 |       } | 
 |       return; | 
 |     } | 
 |   } else if (!visitor_->ValidateStatelessReset( | 
 |                  last_received_packet_info_.destination_address, | 
 |                  last_received_packet_info_.source_address)) { | 
 |     // This packet is received on a probing path. Do not close connection. | 
 |     return; | 
 |   } | 
 |  | 
 |   const std::string error_details = "Received stateless reset."; | 
 |   QUIC_CODE_COUNT(quic_tear_down_local_connection_on_stateless_reset); | 
 |   TearDownLocalConnectionState(QUIC_PUBLIC_RESET, NO_IETF_QUIC_ERROR, | 
 |                                error_details, ConnectionCloseSource::FROM_PEER); | 
 | } | 
 |  | 
 | void QuicConnection::OnKeyUpdate(KeyUpdateReason reason) { | 
 |   QUICHE_DCHECK(support_key_update_for_connection_); | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "Key phase updated for " << reason; | 
 |  | 
 |   lowest_packet_sent_in_current_key_phase_.Clear(); | 
 |   stats_.key_update_count++; | 
 |  | 
 |   // If another key update triggers while the previous | 
 |   // discard_previous_one_rtt_keys_alarm_ hasn't fired yet, cancel it since the | 
 |   // old keys would already be discarded. | 
 |   discard_previous_one_rtt_keys_alarm_->Cancel(); | 
 |  | 
 |   visitor_->OnKeyUpdate(reason); | 
 | } | 
 |  | 
 | void QuicConnection::OnDecryptedFirstPacketInKeyPhase() { | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "OnDecryptedFirstPacketInKeyPhase"; | 
 |   // An endpoint SHOULD retain old read keys for no more than three times the | 
 |   // PTO after having received a packet protected using the new keys. After this | 
 |   // period, old read keys and their corresponding secrets SHOULD be discarded. | 
 |   // | 
 |   // Note that this will cause an unnecessary | 
 |   // discard_previous_one_rtt_keys_alarm_ on the first packet in the 1RTT | 
 |   // encryption level, but this is harmless. | 
 |   discard_previous_one_rtt_keys_alarm_->Set( | 
 |       clock_->ApproximateNow() + sent_packet_manager_.GetPtoDelay() * 3); | 
 | } | 
 |  | 
 | std::unique_ptr<QuicDecrypter> | 
 | QuicConnection::AdvanceKeysAndCreateCurrentOneRttDecrypter() { | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "AdvanceKeysAndCreateCurrentOneRttDecrypter"; | 
 |   return visitor_->AdvanceKeysAndCreateCurrentOneRttDecrypter(); | 
 | } | 
 |  | 
 | std::unique_ptr<QuicEncrypter> QuicConnection::CreateCurrentOneRttEncrypter() { | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "CreateCurrentOneRttEncrypter"; | 
 |   return visitor_->CreateCurrentOneRttEncrypter(); | 
 | } | 
 |  | 
 | void QuicConnection::ClearLastFrames() { | 
 |   should_last_packet_instigate_acks_ = false; | 
 | } | 
 |  | 
 | void QuicConnection::CloseIfTooManyOutstandingSentPackets() { | 
 |   // This occurs if we don't discard old packets we've seen fast enough. It's | 
 |   // possible largest observed is less than leaset unacked. | 
 |   const bool should_close = | 
 |       sent_packet_manager_.GetLargestSentPacket().IsInitialized() && | 
 |       sent_packet_manager_.GetLargestSentPacket() > | 
 |           sent_packet_manager_.GetLeastUnacked() + max_tracked_packets_; | 
 |  | 
 |   if (should_close) { | 
 |     CloseConnection( | 
 |         QUIC_TOO_MANY_OUTSTANDING_SENT_PACKETS, | 
 |         absl::StrCat("More than ", max_tracked_packets_, | 
 |                      " outstanding, least_unacked: ", | 
 |                      sent_packet_manager_.GetLeastUnacked().ToUint64(), | 
 |                      ", packets_processed: ", stats_.packets_processed, | 
 |                      ", last_decrypted_packet_level: ", | 
 |                      EncryptionLevelToString(last_decrypted_packet_level_)), | 
 |         ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |   } | 
 | } | 
 |  | 
 | const QuicFrame QuicConnection::GetUpdatedAckFrame() { | 
 |   QUICHE_DCHECK(!uber_received_packet_manager_.IsAckFrameEmpty( | 
 |       QuicUtils::GetPacketNumberSpace(encryption_level_))) | 
 |       << "Try to retrieve an empty ACK frame"; | 
 |   return uber_received_packet_manager_.GetUpdatedAckFrame( | 
 |       QuicUtils::GetPacketNumberSpace(encryption_level_), | 
 |       clock_->ApproximateNow()); | 
 | } | 
 |  | 
 | void QuicConnection::PopulateStopWaitingFrame( | 
 |     QuicStopWaitingFrame* stop_waiting) { | 
 |   stop_waiting->least_unacked = GetLeastUnacked(); | 
 | } | 
 |  | 
 | QuicPacketNumber QuicConnection::GetLeastUnacked() const { | 
 |   return sent_packet_manager_.GetLeastUnacked(); | 
 | } | 
 |  | 
 | bool QuicConnection::HandleWriteBlocked() { | 
 |   if (!writer_->IsWriteBlocked()) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   visitor_->OnWriteBlocked(); | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeSendInResponseToPacket() { | 
 |   if (!connected_) { | 
 |     return; | 
 |   } | 
 |  | 
 |   // If the writer is blocked, don't attempt to send packets now or in the send | 
 |   // alarm. When the writer unblocks, OnCanWrite() will be called for this | 
 |   // connection to send. | 
 |   if (HandleWriteBlocked()) { | 
 |     return; | 
 |   } | 
 |  | 
 |   // Now that we have received an ack, we might be able to send packets which | 
 |   // are queued locally, or drain streams which are blocked. | 
 |   if (defer_send_in_response_to_packets_) { | 
 |     send_alarm_->Update(clock_->ApproximateNow(), QuicTime::Delta::Zero()); | 
 |   } else { | 
 |     WriteIfNotBlocked(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::MaybeActivateLegacyVersionEncapsulation() { | 
 |   if (!legacy_version_encapsulation_enabled_) { | 
 |     return; | 
 |   } | 
 |   QUICHE_DCHECK(!legacy_version_encapsulation_in_progress_); | 
 |   QUIC_BUG_IF(quic_bug_12714_19, !packet_creator_.CanSetMaxPacketLength()) | 
 |       << "Cannot activate Legacy Version Encapsulation mid-packet"; | 
 |   QUIC_BUG_IF(quic_bug_12714_20, coalesced_packet_.length() != 0u) | 
 |       << "Cannot activate Legacy Version Encapsulation mid-coalesced-packet"; | 
 |   legacy_version_encapsulation_in_progress_ = true; | 
 |   MaybeUpdatePacketCreatorMaxPacketLengthAndPadding(); | 
 | } | 
 | void QuicConnection::MaybeDisactivateLegacyVersionEncapsulation() { | 
 |   if (!legacy_version_encapsulation_in_progress_) { | 
 |     return; | 
 |   } | 
 |   // Flush any remaining packet before disactivating encapsulation. | 
 |   packet_creator_.FlushCurrentPacket(); | 
 |   QUICHE_DCHECK(legacy_version_encapsulation_enabled_); | 
 |   legacy_version_encapsulation_in_progress_ = false; | 
 |   MaybeUpdatePacketCreatorMaxPacketLengthAndPadding(); | 
 | } | 
 |  | 
 | size_t QuicConnection::SendCryptoData(EncryptionLevel level, | 
 |                                       size_t write_length, | 
 |                                       QuicStreamOffset offset) { | 
 |   if (write_length == 0) { | 
 |     QUIC_BUG(quic_bug_10511_18) << "Attempt to send empty crypto frame"; | 
 |     return 0; | 
 |   } | 
 |   if (level == ENCRYPTION_INITIAL) { | 
 |     MaybeActivateLegacyVersionEncapsulation(); | 
 |   } | 
 |   size_t consumed_length; | 
 |   { | 
 |     ScopedPacketFlusher flusher(this); | 
 |     consumed_length = | 
 |         packet_creator_.ConsumeCryptoData(level, write_length, offset); | 
 |   }  // Added scope ensures packets are flushed before continuing. | 
 |   MaybeDisactivateLegacyVersionEncapsulation(); | 
 |   return consumed_length; | 
 | } | 
 |  | 
 | QuicConsumedData QuicConnection::SendStreamData(QuicStreamId id, | 
 |                                                 size_t write_length, | 
 |                                                 QuicStreamOffset offset, | 
 |                                                 StreamSendingState state) { | 
 |   if (state == NO_FIN && write_length == 0) { | 
 |     QUIC_BUG(quic_bug_10511_19) << "Attempt to send empty stream frame"; | 
 |     return QuicConsumedData(0, false); | 
 |   } | 
 |  | 
 |   if (packet_creator_.encryption_level() == ENCRYPTION_INITIAL && | 
 |       QuicUtils::IsCryptoStreamId(transport_version(), id)) { | 
 |     MaybeActivateLegacyVersionEncapsulation(); | 
 |   } | 
 |   if (perspective_ == Perspective::IS_SERVER && | 
 |       version().CanSendCoalescedPackets() && !IsHandshakeConfirmed()) { | 
 |     if (in_on_retransmission_time_out_ && | 
 |         coalesced_packet_.NumberOfPackets() == 0u) { | 
 |       // PTO fires while handshake is not confirmed. Do not preempt handshake | 
 |       // data with stream data. | 
 |       QUIC_CODE_COUNT(quic_try_to_send_half_rtt_data_when_pto_fires); | 
 |       return QuicConsumedData(0, false); | 
 |     } | 
 |     if (coalesced_packet_.ContainsPacketOfEncryptionLevel(ENCRYPTION_INITIAL) && | 
 |         coalesced_packet_.NumberOfPackets() == 1u) { | 
 |       // Handshake is not confirmed yet, if there is only an initial packet in | 
 |       // the coalescer, try to bundle an ENCRYPTION_HANDSHAKE packet before | 
 |       // sending stream data. | 
 |       sent_packet_manager_.RetransmitDataOfSpaceIfAny(HANDSHAKE_DATA); | 
 |     } | 
 |   } | 
 |   QuicConsumedData consumed_data(0, false); | 
 |   { | 
 |     // Opportunistically bundle an ack with every outgoing packet. | 
 |     // Particularly, we want to bundle with handshake packets since we don't | 
 |     // know which decrypter will be used on an ack packet following a handshake | 
 |     // packet (a handshake packet from client to server could result in a REJ or | 
 |     // a SHLO from the server, leading to two different decrypters at the | 
 |     // server.) | 
 |     ScopedPacketFlusher flusher(this); | 
 |     consumed_data = | 
 |         packet_creator_.ConsumeData(id, write_length, offset, state); | 
 |   }  // Added scope ensures packets are flushed before continuing. | 
 |   MaybeDisactivateLegacyVersionEncapsulation(); | 
 |   return consumed_data; | 
 | } | 
 |  | 
 | bool QuicConnection::SendControlFrame(const QuicFrame& frame) { | 
 |   if (SupportsMultiplePacketNumberSpaces() && | 
 |       (encryption_level_ == ENCRYPTION_INITIAL || | 
 |        encryption_level_ == ENCRYPTION_HANDSHAKE) && | 
 |       frame.type != PING_FRAME) { | 
 |     // Allow PING frame to be sent without APPLICATION key. For example, when | 
 |     // anti-amplification limit is used, client needs to send something to avoid | 
 |     // handshake deadlock. | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Failed to send control frame: " << frame | 
 |                   << " at encryption level: " << encryption_level_; | 
 |     return false; | 
 |   } | 
 |   ScopedPacketFlusher flusher(this); | 
 |   const bool consumed = | 
 |       packet_creator_.ConsumeRetransmittableControlFrame(frame); | 
 |   if (!consumed) { | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Failed to send control frame: " << frame; | 
 |     return false; | 
 |   } | 
 |   if (frame.type == PING_FRAME) { | 
 |     // Flush PING frame immediately. | 
 |     packet_creator_.FlushCurrentPacket(); | 
 |     stats_.ping_frames_sent++; | 
 |     if (debug_visitor_ != nullptr) { | 
 |       debug_visitor_->OnPingSent(); | 
 |     } | 
 |   } | 
 |   if (frame.type == BLOCKED_FRAME) { | 
 |     stats_.blocked_frames_sent++; | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::OnStreamReset(QuicStreamId id, | 
 |                                    QuicRstStreamErrorCode error) { | 
 |   if (error == QUIC_STREAM_NO_ERROR) { | 
 |     // All data for streams which are reset with QUIC_STREAM_NO_ERROR must | 
 |     // be received by the peer. | 
 |     return; | 
 |   } | 
 |   // Flush stream frames of reset stream. | 
 |   if (packet_creator_.HasPendingStreamFramesOfStream(id)) { | 
 |     ScopedPacketFlusher flusher(this); | 
 |     packet_creator_.FlushCurrentPacket(); | 
 |   } | 
 |   // TODO(ianswett): Consider checking for 3 RTOs when the last stream is | 
 |   // cancelled as well. | 
 | } | 
 |  | 
 | const QuicConnectionStats& QuicConnection::GetStats() { | 
 |   const RttStats* rtt_stats = sent_packet_manager_.GetRttStats(); | 
 |  | 
 |   // Update rtt and estimated bandwidth. | 
 |   QuicTime::Delta min_rtt = rtt_stats->min_rtt(); | 
 |   if (min_rtt.IsZero()) { | 
 |     // If min RTT has not been set, use initial RTT instead. | 
 |     min_rtt = rtt_stats->initial_rtt(); | 
 |   } | 
 |   stats_.min_rtt_us = min_rtt.ToMicroseconds(); | 
 |  | 
 |   QuicTime::Delta srtt = rtt_stats->SmoothedOrInitialRtt(); | 
 |   stats_.srtt_us = srtt.ToMicroseconds(); | 
 |  | 
 |   stats_.estimated_bandwidth = sent_packet_manager_.BandwidthEstimate(); | 
 |   sent_packet_manager_.GetSendAlgorithm()->PopulateConnectionStats(&stats_); | 
 |   stats_.egress_mtu = long_term_mtu_; | 
 |   stats_.ingress_mtu = largest_received_packet_size_; | 
 |   return stats_; | 
 | } | 
 |  | 
 | void QuicConnection::OnCoalescedPacket(const QuicEncryptedPacket& packet) { | 
 |   QueueCoalescedPacket(packet); | 
 | } | 
 |  | 
 | void QuicConnection::OnUndecryptablePacket(const QuicEncryptedPacket& packet, | 
 |                                            EncryptionLevel decryption_level, | 
 |                                            bool has_decryption_key) { | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Received undecryptable packet of length " | 
 |                 << packet.length() << " with" | 
 |                 << (has_decryption_key ? "" : "out") << " key at level " | 
 |                 << decryption_level | 
 |                 << " while connection is at encryption level " | 
 |                 << encryption_level_; | 
 |   QUICHE_DCHECK(EncryptionLevelIsValid(decryption_level)); | 
 |   if (encryption_level_ != ENCRYPTION_FORWARD_SECURE) { | 
 |     ++stats_.undecryptable_packets_received_before_handshake_complete; | 
 |   } | 
 |  | 
 |   const bool should_enqueue = | 
 |       ShouldEnqueueUnDecryptablePacket(decryption_level, has_decryption_key); | 
 |   if (should_enqueue) { | 
 |     QueueUndecryptablePacket(packet, decryption_level); | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnUndecryptablePacket(decryption_level, | 
 |                                           /*dropped=*/!should_enqueue); | 
 |   } | 
 |  | 
 |   if (has_decryption_key) { | 
 |     stats_.num_failed_authentication_packets_received++; | 
 |     if (version().UsesTls()) { | 
 |       // Should always be non-null if has_decryption_key is true. | 
 |       QUICHE_DCHECK(framer_.GetDecrypter(decryption_level)); | 
 |       const QuicPacketCount integrity_limit = | 
 |           framer_.GetDecrypter(decryption_level)->GetIntegrityLimit(); | 
 |       QUIC_DVLOG(2) << ENDPOINT << "Checking AEAD integrity limits:" | 
 |                     << " num_failed_authentication_packets_received=" | 
 |                     << stats_.num_failed_authentication_packets_received | 
 |                     << " integrity_limit=" << integrity_limit; | 
 |       if (stats_.num_failed_authentication_packets_received >= | 
 |           integrity_limit) { | 
 |         const std::string error_details = absl::StrCat( | 
 |             "decrypter integrity limit reached:" | 
 |             " num_failed_authentication_packets_received=", | 
 |             stats_.num_failed_authentication_packets_received, | 
 |             " integrity_limit=", integrity_limit); | 
 |         CloseConnection(QUIC_AEAD_LIMIT_REACHED, error_details, | 
 |                         ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |       } | 
 |     } | 
 |   } | 
 |  | 
 |   if (version().UsesTls() && perspective_ == Perspective::IS_SERVER && | 
 |       decryption_level == ENCRYPTION_ZERO_RTT && !has_decryption_key && | 
 |       had_zero_rtt_decrypter_) { | 
 |     QUIC_CODE_COUNT_N( | 
 |         quic_server_received_tls_zero_rtt_packet_after_discarding_decrypter, 1, | 
 |         3); | 
 |     stats_ | 
 |         .num_tls_server_zero_rtt_packets_received_after_discarding_decrypter++; | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::ShouldEnqueueUnDecryptablePacket( | 
 |     EncryptionLevel decryption_level, bool has_decryption_key) const { | 
 |   if (has_decryption_key) { | 
 |     // We already have the key for this decryption level, therefore no | 
 |     // future keys will allow it be decrypted. | 
 |     return false; | 
 |   } | 
 |   if (IsHandshakeComplete()) { | 
 |     // We do not expect to install any further keys. | 
 |     return false; | 
 |   } | 
 |   if (undecryptable_packets_.size() >= max_undecryptable_packets_) { | 
 |     // We do not queue more than max_undecryptable_packets_ packets. | 
 |     return false; | 
 |   } | 
 |   if (version().KnowsWhichDecrypterToUse() && | 
 |       decryption_level == ENCRYPTION_INITIAL) { | 
 |     // When the corresponding decryption key is not available, all | 
 |     // non-Initial packets should be buffered until the handshake is complete. | 
 |     return false; | 
 |   } | 
 |   if (perspective_ == Perspective::IS_CLIENT && version().UsesTls() && | 
 |       decryption_level == ENCRYPTION_ZERO_RTT) { | 
 |     // Only clients send Zero RTT packets in IETF QUIC. | 
 |     QUIC_PEER_BUG(quic_peer_bug_client_received_zero_rtt) | 
 |         << "Client received a Zero RTT packet, not buffering."; | 
 |     return false; | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | std::string QuicConnection::UndecryptablePacketsInfo() const { | 
 |   std::string info = absl::StrCat( | 
 |       "num_undecryptable_packets: ", undecryptable_packets_.size(), " {"); | 
 |   for (const auto& packet : undecryptable_packets_) { | 
 |     absl::StrAppend(&info, "[", | 
 |                     EncryptionLevelToString(packet.encryption_level), ", ", | 
 |                     packet.packet->length(), "]"); | 
 |   } | 
 |   absl::StrAppend(&info, "}"); | 
 |   return info; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeUpdatePacketCreatorMaxPacketLengthAndPadding() { | 
 |   QuicByteCount max_packet_length = GetLimitedMaxPacketSize(long_term_mtu_); | 
 |   if (legacy_version_encapsulation_in_progress_) { | 
 |     QUICHE_DCHECK(legacy_version_encapsulation_enabled_); | 
 |     const QuicByteCount minimum_overhead = | 
 |         QuicLegacyVersionEncapsulator::GetMinimumOverhead( | 
 |             legacy_version_encapsulation_sni_); | 
 |     if (max_packet_length < minimum_overhead) { | 
 |       QUIC_BUG(quic_bug_10511_20) | 
 |           << "Cannot apply Legacy Version Encapsulation overhead because " | 
 |           << "max_packet_length " << max_packet_length << " < minimum_overhead " | 
 |           << minimum_overhead; | 
 |       legacy_version_encapsulation_in_progress_ = false; | 
 |       legacy_version_encapsulation_enabled_ = false; | 
 |       MaybeUpdatePacketCreatorMaxPacketLengthAndPadding(); | 
 |       return; | 
 |     } | 
 |     max_packet_length -= minimum_overhead; | 
 |   } | 
 |   packet_creator_.SetMaxPacketLength(max_packet_length); | 
 | } | 
 |  | 
 | void QuicConnection::ProcessUdpPacket(const QuicSocketAddress& self_address, | 
 |                                       const QuicSocketAddress& peer_address, | 
 |                                       const QuicReceivedPacket& packet) { | 
 |   if (!connected_) { | 
 |     return; | 
 |   } | 
 |   QUIC_DVLOG(2) << ENDPOINT << "Received encrypted " << packet.length() | 
 |                 << " bytes:" << std::endl | 
 |                 << quiche::QuicheTextUtils::HexDump( | 
 |                        absl::string_view(packet.data(), packet.length())); | 
 |   QUIC_BUG_IF(quic_bug_12714_21, current_packet_data_ != nullptr) | 
 |       << "ProcessUdpPacket must not be called while processing a packet."; | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPacketReceived(self_address, peer_address, packet); | 
 |   } | 
 |   last_received_packet_info_ = | 
 |       ReceivedPacketInfo(self_address, peer_address, packet.receipt_time()); | 
 |   last_size_ = packet.length(); | 
 |   current_packet_data_ = packet.data(); | 
 |  | 
 |   if (!default_path_.self_address.IsInitialized()) { | 
 |     default_path_.self_address = last_received_packet_info_.destination_address; | 
 |   } | 
 |  | 
 |   if (!direct_peer_address_.IsInitialized()) { | 
 |     UpdatePeerAddress(last_received_packet_info_.source_address); | 
 |   } | 
 |  | 
 |   if (!default_path_.peer_address.IsInitialized()) { | 
 |     const QuicSocketAddress effective_peer_addr = | 
 |         GetEffectivePeerAddressFromCurrentPacket(); | 
 |  | 
 |     // The default path peer_address must be initialized at the beginning of the | 
 |     // first packet processed(here). If effective_peer_addr is uninitialized, | 
 |     // just set effective_peer_address_ to the direct peer address. | 
 |     default_path_.peer_address = effective_peer_addr.IsInitialized() | 
 |                                      ? effective_peer_addr | 
 |                                      : direct_peer_address_; | 
 |   } | 
 |  | 
 |   stats_.bytes_received += packet.length(); | 
 |   ++stats_.packets_received; | 
 |   if (!count_bytes_on_alternative_path_separately_) { | 
 |     if (EnforceAntiAmplificationLimit()) { | 
 |       default_path_.bytes_received_before_address_validation += last_size_; | 
 |     } | 
 |   } else if (IsDefaultPath(last_received_packet_info_.destination_address, | 
 |                            last_received_packet_info_.source_address) && | 
 |              EnforceAntiAmplificationLimit()) { | 
 |     QUIC_CODE_COUNT_N(quic_count_bytes_on_alternative_path_seperately, 1, 5); | 
 |     last_received_packet_info_.received_bytes_counted = true; | 
 |     default_path_.bytes_received_before_address_validation += last_size_; | 
 |   } | 
 |  | 
 |   // Ensure the time coming from the packet reader is within 2 minutes of now. | 
 |   if (std::abs((packet.receipt_time() - clock_->ApproximateNow()).ToSeconds()) > | 
 |       2 * 60) { | 
 |     QUIC_BUG(quic_bug_10511_21) | 
 |         << "Packet receipt time:" << packet.receipt_time().ToDebuggingValue() | 
 |         << " too far from current time:" | 
 |         << clock_->ApproximateNow().ToDebuggingValue(); | 
 |   } | 
 |   QUIC_DVLOG(1) << ENDPOINT << "time of last received packet: " | 
 |                 << packet.receipt_time().ToDebuggingValue() << " from peer " | 
 |                 << last_received_packet_info_.source_address; | 
 |  | 
 |   ScopedPacketFlusher flusher(this); | 
 |   if (!framer_.ProcessPacket(packet)) { | 
 |     // If we are unable to decrypt this packet, it might be | 
 |     // because the CHLO or SHLO packet was lost. | 
 |     QUIC_DVLOG(1) << ENDPOINT | 
 |                   << "Unable to process packet.  Last packet processed: " | 
 |                   << last_header_.packet_number; | 
 |     current_packet_data_ = nullptr; | 
 |     is_current_packet_connectivity_probing_ = false; | 
 |  | 
 |     MaybeProcessCoalescedPackets(); | 
 |     return; | 
 |   } | 
 |  | 
 |   ++stats_.packets_processed; | 
 |  | 
 |   QUIC_DLOG_IF(INFO, active_effective_peer_migration_type_ != NO_CHANGE) | 
 |       << "sent_packet_manager_.GetLargestObserved() = " | 
 |       << sent_packet_manager_.GetLargestObserved() | 
 |       << ", highest_packet_sent_before_effective_peer_migration_ = " | 
 |       << highest_packet_sent_before_effective_peer_migration_; | 
 |   if (!validate_client_addresses_ && | 
 |       active_effective_peer_migration_type_ != NO_CHANGE && | 
 |       sent_packet_manager_.GetLargestObserved().IsInitialized() && | 
 |       (!highest_packet_sent_before_effective_peer_migration_.IsInitialized() || | 
 |        sent_packet_manager_.GetLargestObserved() > | 
 |            highest_packet_sent_before_effective_peer_migration_)) { | 
 |     if (perspective_ == Perspective::IS_SERVER) { | 
 |       OnEffectivePeerMigrationValidated(); | 
 |     } | 
 |   } | 
 |  | 
 |   if (!MaybeProcessCoalescedPackets()) { | 
 |     MaybeProcessUndecryptablePackets(); | 
 |     MaybeSendInResponseToPacket(); | 
 |   } | 
 |   SetPingAlarm(); | 
 |   RetirePeerIssuedConnectionIdsNoLongerOnPath(); | 
 |   current_packet_data_ = nullptr; | 
 |   is_current_packet_connectivity_probing_ = false; | 
 | } | 
 |  | 
 | void QuicConnection::OnBlockedWriterCanWrite() { | 
 |   writer_->SetWritable(); | 
 |   OnCanWrite(); | 
 | } | 
 |  | 
 | void QuicConnection::OnCanWrite() { | 
 |   if (!connected_) { | 
 |     return; | 
 |   } | 
 |   if (writer_->IsWriteBlocked()) { | 
 |     const std::string error_details = | 
 |         "Writer is blocked while calling OnCanWrite."; | 
 |     QUIC_BUG(quic_bug_10511_22) << ENDPOINT << error_details; | 
 |     CloseConnection(QUIC_INTERNAL_ERROR, error_details, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return; | 
 |   } | 
 |  | 
 |   ScopedPacketFlusher flusher(this); | 
 |  | 
 |   WriteQueuedPackets(); | 
 |   const QuicTime ack_timeout = | 
 |       uber_received_packet_manager_.GetEarliestAckTimeout(); | 
 |   if (ack_timeout.IsInitialized() && ack_timeout <= clock_->ApproximateNow()) { | 
 |     // Send an ACK now because either 1) we were write blocked when we last | 
 |     // tried to send an ACK, or 2) both ack alarm and send alarm were set to | 
 |     // go off together. | 
 |     if (SupportsMultiplePacketNumberSpaces()) { | 
 |       SendAllPendingAcks(); | 
 |     } else { | 
 |       SendAck(); | 
 |     } | 
 |   } | 
 |  | 
 |   // TODO(danzh) PATH_RESPONSE is of more interest to the peer than ACK, | 
 |   // evaluate if it's worth to send them before sending ACKs. | 
 |   while (!pending_path_challenge_payloads_.empty()) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_send_path_response2, 4, 5); | 
 |     const PendingPathChallenge& pending_path_challenge = | 
 |         pending_path_challenge_payloads_.front(); | 
 |     // Note connection_migration_use_cid_ will depends on | 
 |     // quic_drop_unsent_path_response flag eventually, and hence the empty | 
 |     // effective_peer_address here will not be used. | 
 |     if (!SendPathResponse(pending_path_challenge.received_path_challenge, | 
 |                           pending_path_challenge.peer_address, | 
 |                           /*effective_peer_address=*/QuicSocketAddress())) { | 
 |       break; | 
 |     } | 
 |     pending_path_challenge_payloads_.pop_front(); | 
 |   } | 
 |  | 
 |   // Sending queued packets may have caused the socket to become write blocked, | 
 |   // or the congestion manager to prohibit sending. | 
 |   if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) { | 
 |     return; | 
 |   } | 
 |  | 
 |   // Tell the session it can write. | 
 |   visitor_->OnCanWrite(); | 
 |  | 
 |   // After the visitor writes, it may have caused the socket to become write | 
 |   // blocked or the congestion manager to prohibit sending, so check again. | 
 |   if (visitor_->WillingAndAbleToWrite() && !send_alarm_->IsSet() && | 
 |       CanWrite(HAS_RETRANSMITTABLE_DATA)) { | 
 |     // We're not write blocked, but some data wasn't written. Register for | 
 |     // 'immediate' resumption so we'll keep writing after other connections. | 
 |     send_alarm_->Set(clock_->ApproximateNow()); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::WriteIfNotBlocked() { | 
 |   if (framer().is_processing_packet()) { | 
 |     QUIC_BUG(connection_write_mid_packet_processing) | 
 |         << ENDPOINT << "Tried to write in mid of packet processing"; | 
 |     return; | 
 |   } | 
 |   if (!HandleWriteBlocked()) { | 
 |     OnCanWrite(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::MaybeClearQueuedPacketsOnPathChange() { | 
 |   if (connection_migration_use_new_cid_ && | 
 |       peer_issued_cid_manager_ != nullptr && HasQueuedPackets()) { | 
 |     // Discard packets serialized with the connection ID on the old code path. | 
 |     // It is possible to clear queued packets only if connection ID changes. | 
 |     // However, the case where connection ID is unchanged and queued packets are | 
 |     // non-empty is quite rare. | 
 |     ClearQueuedPackets(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::ReplaceInitialServerConnectionId( | 
 |     const QuicConnectionId& new_server_connection_id) { | 
 |   QUICHE_DCHECK(perspective_ == Perspective::IS_CLIENT); | 
 |   if (version().HasIetfQuicFrames()) { | 
 |     if (new_server_connection_id.IsEmpty()) { | 
 |       peer_issued_cid_manager_ = nullptr; | 
 |     } else { | 
 |       if (peer_issued_cid_manager_ != nullptr) { | 
 |         QUIC_BUG_IF(quic_bug_12714_22, | 
 |                     !peer_issued_cid_manager_->IsConnectionIdActive( | 
 |                         default_path_.server_connection_id)) | 
 |             << "Connection ID replaced header is no longer active. old id: " | 
 |             << default_path_.server_connection_id | 
 |             << " new_id: " << new_server_connection_id; | 
 |         peer_issued_cid_manager_->ReplaceConnectionId( | 
 |             default_path_.server_connection_id, new_server_connection_id); | 
 |       } else { | 
 |         peer_issued_cid_manager_ = | 
 |             std::make_unique<QuicPeerIssuedConnectionIdManager>( | 
 |                 kMinNumOfActiveConnectionIds, new_server_connection_id, clock_, | 
 |                 alarm_factory_, this, context()); | 
 |       } | 
 |     } | 
 |   } | 
 |   default_path_.server_connection_id = new_server_connection_id; | 
 |   packet_creator_.SetServerConnectionId(default_path_.server_connection_id); | 
 | } | 
 |  | 
 | void QuicConnection::FindMatchingOrNewClientConnectionIdOrToken( | 
 |     const PathState& default_path, const PathState& alternative_path, | 
 |     const QuicConnectionId& server_connection_id, | 
 |     QuicConnectionId* client_connection_id, | 
 |     absl::optional<StatelessResetToken>* stateless_reset_token) { | 
 |   QUICHE_DCHECK(perspective_ == Perspective::IS_SERVER); | 
 |   if (peer_issued_cid_manager_ == nullptr || | 
 |       server_connection_id == default_path.server_connection_id) { | 
 |     *client_connection_id = default_path.client_connection_id; | 
 |     *stateless_reset_token = default_path.stateless_reset_token; | 
 |     return; | 
 |   } | 
 |   if (server_connection_id == alternative_path_.server_connection_id) { | 
 |     *client_connection_id = alternative_path.client_connection_id; | 
 |     *stateless_reset_token = alternative_path.stateless_reset_token; | 
 |     return; | 
 |   } | 
 |   if (!connection_migration_use_new_cid_) { | 
 |     QUIC_BUG(quic_bug_46004) << "Cannot find matching connection ID."; | 
 |     return; | 
 |   } | 
 |   auto* connection_id_data = | 
 |       peer_issued_cid_manager_->ConsumeOneUnusedConnectionId(); | 
 |   if (connection_id_data == nullptr) { | 
 |     return; | 
 |   } | 
 |   *client_connection_id = connection_id_data->connection_id; | 
 |   *stateless_reset_token = connection_id_data->stateless_reset_token; | 
 | } | 
 |  | 
 | bool QuicConnection::FindOnPathConnectionIds( | 
 |     const QuicSocketAddress& self_address, | 
 |     const QuicSocketAddress& peer_address, | 
 |     QuicConnectionId* client_connection_id, | 
 |     QuicConnectionId* server_connection_id) const { | 
 |   if (IsDefaultPath(self_address, peer_address)) { | 
 |     *client_connection_id = default_path_.client_connection_id, | 
 |     *server_connection_id = default_path_.server_connection_id; | 
 |     return true; | 
 |   } | 
 |   if (IsAlternativePath(self_address, peer_address)) { | 
 |     *client_connection_id = alternative_path_.client_connection_id, | 
 |     *server_connection_id = alternative_path_.server_connection_id; | 
 |     return true; | 
 |   } | 
 |   return false; | 
 | } | 
 |  | 
 | void QuicConnection::SetDefaultPathState(PathState new_path_state) { | 
 |   default_path_ = std::move(new_path_state); | 
 |   if (connection_migration_use_new_cid_) { | 
 |     packet_creator_.SetClientConnectionId(default_path_.client_connection_id); | 
 |     packet_creator_.SetServerConnectionId(default_path_.server_connection_id); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::ProcessValidatedPacket(const QuicPacketHeader& header) { | 
 |   if (perspective_ == Perspective::IS_CLIENT && version().HasIetfQuicFrames() && | 
 |       direct_peer_address_.IsInitialized() && | 
 |       last_received_packet_info_.source_address.IsInitialized() && | 
 |       direct_peer_address_ != last_received_packet_info_.source_address && | 
 |       !visitor_->IsKnownServerAddress( | 
 |           last_received_packet_info_.source_address)) { | 
 |     // TODO(haoyuewang) Revisit this when preferred_address transport parameter | 
 |     // is used on the client side. | 
 |     // Discard packets received from unseen server addresses. | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (perspective_ == Perspective::IS_SERVER && | 
 |       default_path_.self_address.IsInitialized() && | 
 |       last_received_packet_info_.destination_address.IsInitialized() && | 
 |       default_path_.self_address != | 
 |           last_received_packet_info_.destination_address) { | 
 |     // Allow change between pure IPv4 and equivalent mapped IPv4 address. | 
 |     if (default_path_.self_address.port() != | 
 |             last_received_packet_info_.destination_address.port() || | 
 |         default_path_.self_address.host().Normalized() != | 
 |             last_received_packet_info_.destination_address.host() | 
 |                 .Normalized()) { | 
 |       if (!visitor_->AllowSelfAddressChange()) { | 
 |         CloseConnection( | 
 |             QUIC_ERROR_MIGRATING_ADDRESS, | 
 |             "Self address migration is not supported at the server.", | 
 |             ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |         return false; | 
 |       } | 
 |     } | 
 |     default_path_.self_address = last_received_packet_info_.destination_address; | 
 |   } | 
 |  | 
 |   if (PacketCanReplaceServerConnectionId(header, perspective_) && | 
 |       default_path_.server_connection_id != header.source_connection_id) { | 
 |     QUICHE_DCHECK_EQ(header.long_packet_type, INITIAL); | 
 |     if (server_connection_id_replaced_by_initial_) { | 
 |       QUIC_DLOG(ERROR) << ENDPOINT << "Refusing to replace connection ID " | 
 |                        << default_path_.server_connection_id << " with " | 
 |                        << header.source_connection_id; | 
 |       return false; | 
 |     } | 
 |     server_connection_id_replaced_by_initial_ = true; | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Replacing connection ID " | 
 |                     << default_path_.server_connection_id << " with " | 
 |                     << header.source_connection_id; | 
 |     if (!original_destination_connection_id_.has_value()) { | 
 |       original_destination_connection_id_ = default_path_.server_connection_id; | 
 |     } | 
 |     ReplaceInitialServerConnectionId(header.source_connection_id); | 
 |   } | 
 |  | 
 |   if (!ValidateReceivedPacketNumber(header.packet_number)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (!version_negotiated_) { | 
 |     if (perspective_ == Perspective::IS_CLIENT) { | 
 |       QUICHE_DCHECK(!header.version_flag || header.form != GOOGLE_QUIC_PACKET); | 
 |       if (!version().HasIetfInvariantHeader()) { | 
 |         // If the client gets a packet without the version flag from the server | 
 |         // it should stop sending version since the version negotiation is done. | 
 |         // IETF QUIC stops sending version once encryption level switches to | 
 |         // forward secure. | 
 |         packet_creator_.StopSendingVersion(); | 
 |       } | 
 |       version_negotiated_ = true; | 
 |       OnSuccessfulVersionNegotiation(); | 
 |     } | 
 |   } | 
 |  | 
 |   if (last_size_ > largest_received_packet_size_) { | 
 |     largest_received_packet_size_ = last_size_; | 
 |   } | 
 |  | 
 |   if (perspective_ == Perspective::IS_SERVER && | 
 |       encryption_level_ == ENCRYPTION_INITIAL && | 
 |       last_size_ > packet_creator_.max_packet_length()) { | 
 |     if (GetQuicFlag(FLAGS_quic_use_lower_server_response_mtu_for_test)) { | 
 |       SetMaxPacketLength(std::min(last_size_, QuicByteCount(1250))); | 
 |     } else { | 
 |       SetMaxPacketLength(last_size_); | 
 |     } | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::ValidateReceivedPacketNumber( | 
 |     QuicPacketNumber packet_number) { | 
 |   // If this packet has already been seen, or the sender has told us that it | 
 |   // will not be retransmitted, then stop processing the packet. | 
 |   if (!uber_received_packet_manager_.IsAwaitingPacket( | 
 |           last_decrypted_packet_level_, packet_number)) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Packet " << packet_number | 
 |                     << " no longer being waited for at level " | 
 |                     << static_cast<int>(last_decrypted_packet_level_) | 
 |                     << ".  Discarding."; | 
 |     if (debug_visitor_ != nullptr) { | 
 |       debug_visitor_->OnDuplicatePacket(packet_number); | 
 |     } | 
 |     return false; | 
 |   } | 
 |  | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::WriteQueuedPackets() { | 
 |   QUICHE_DCHECK(!writer_->IsWriteBlocked()); | 
 |  | 
 |   QUIC_CLIENT_HISTOGRAM_COUNTS("QuicSession.NumQueuedPacketsBeforeWrite", | 
 |                                buffered_packets_.size(), 1, 1000, 50, ""); | 
 |  | 
 |   while (!buffered_packets_.empty()) { | 
 |     if (HandleWriteBlocked()) { | 
 |       break; | 
 |     } | 
 |     const BufferedPacket& packet = buffered_packets_.front(); | 
 |     WriteResult result = writer_->WritePacket( | 
 |         packet.encrypted_buffer.data(), packet.encrypted_buffer.length(), | 
 |         packet.self_address.host(), packet.peer_address, per_packet_options_); | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Sending buffered packet, result: " << result; | 
 |     if (IsMsgTooBig(result) && | 
 |         packet.encrypted_buffer.length() > long_term_mtu_) { | 
 |       // When MSG_TOO_BIG is returned, the system typically knows what the | 
 |       // actual MTU is, so there is no need to probe further. | 
 |       // TODO(wub): Reduce max packet size to a safe default, or the actual MTU. | 
 |       mtu_discoverer_.Disable(); | 
 |       mtu_discovery_alarm_->Cancel(); | 
 |       buffered_packets_.pop_front(); | 
 |       continue; | 
 |     } | 
 |     if (IsWriteError(result.status)) { | 
 |       OnWriteError(result.error_code); | 
 |       break; | 
 |     } | 
 |     if (result.status == WRITE_STATUS_OK || | 
 |         result.status == WRITE_STATUS_BLOCKED_DATA_BUFFERED) { | 
 |       buffered_packets_.pop_front(); | 
 |     } | 
 |     if (IsWriteBlockedStatus(result.status)) { | 
 |       visitor_->OnWriteBlocked(); | 
 |       break; | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::SendProbingRetransmissions() { | 
 |   while (sent_packet_manager_.GetSendAlgorithm()->ShouldSendProbingPacket() && | 
 |          CanWrite(HAS_RETRANSMITTABLE_DATA)) { | 
 |     if (!visitor_->SendProbingData()) { | 
 |       QUIC_DVLOG(1) | 
 |           << "Cannot send probing retransmissions: nothing to retransmit."; | 
 |       break; | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::MarkZeroRttPacketsForRetransmission(int reject_reason) { | 
 |   sent_packet_manager_.MarkZeroRttPacketsForRetransmission(); | 
 |   if (debug_visitor_ != nullptr && version().UsesTls()) { | 
 |     debug_visitor_->OnZeroRttRejected(reject_reason); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::NeuterUnencryptedPackets() { | 
 |   sent_packet_manager_.NeuterUnencryptedPackets(); | 
 |   // This may have changed the retransmission timer, so re-arm it. | 
 |   SetRetransmissionAlarm(); | 
 |   if (default_enable_5rto_blackhole_detection_) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_default_enable_5rto_blackhole_detection2, | 
 |                                  1, 3); | 
 |     // Consider this as forward progress since this is called when initial key | 
 |     // gets discarded (or previous unencrypted data is not needed anymore). | 
 |     OnForwardProgressMade(); | 
 |   } | 
 |   if (SupportsMultiplePacketNumberSpaces()) { | 
 |     // Stop sending ack of initial packet number space. | 
 |     uber_received_packet_manager_.ResetAckStates(ENCRYPTION_INITIAL); | 
 |     // Re-arm ack alarm. | 
 |     ack_alarm_->Update(uber_received_packet_manager_.GetEarliestAckTimeout(), | 
 |                        kAlarmGranularity); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::ShouldGeneratePacket( | 
 |     HasRetransmittableData retransmittable, | 
 |     IsHandshake handshake) { | 
 |   QUICHE_DCHECK(handshake != IS_HANDSHAKE || | 
 |                 QuicVersionUsesCryptoFrames(transport_version())) | 
 |       << ENDPOINT | 
 |       << "Handshake in STREAM frames should not check ShouldGeneratePacket"; | 
 |   if (peer_issued_cid_manager_ != nullptr && | 
 |       packet_creator_.GetDestinationConnectionId().IsEmpty()) { | 
 |     QUICHE_DCHECK(version().HasIetfQuicFrames()); | 
 |     QUIC_CODE_COUNT(quic_generate_packet_blocked_by_no_connection_id); | 
 |     QUIC_BUG_IF(quic_bug_90265_1, perspective_ == Perspective::IS_CLIENT); | 
 |     QUIC_DLOG(INFO) << ENDPOINT | 
 |                     << "There is no destination connection ID available to " | 
 |                        "generate packet."; | 
 |     return false; | 
 |   } | 
 |   if (!count_bytes_on_alternative_path_separately_) { | 
 |     return CanWrite(retransmittable); | 
 |   } | 
 |   QUIC_CODE_COUNT_N(quic_count_bytes_on_alternative_path_seperately, 4, 5); | 
 |   if (IsDefaultPath(default_path_.self_address, | 
 |                     packet_creator_.peer_address())) { | 
 |     return CanWrite(retransmittable); | 
 |   } | 
 |   // This is checking on the alternative path with a different peer address. The | 
 |   // self address and the writer used are the same as the default path. In the | 
 |   // case of different self address and writer, writing packet would use a | 
 |   // differnt code path without checking the states of the default writer. | 
 |   return connected_ && !HandleWriteBlocked(); | 
 | } | 
 |  | 
 | const QuicFrames QuicConnection::MaybeBundleAckOpportunistically() { | 
 |   if (!ack_frequency_sent_ && sent_packet_manager_.CanSendAckFrequency()) { | 
 |     if (packet_creator_.NextSendingPacketNumber() >= | 
 |         FirstSendingPacketNumber() + kMinReceivedBeforeAckDecimation) { | 
 |       QUIC_RELOADABLE_FLAG_COUNT_N(quic_can_send_ack_frequency, 3, 3); | 
 |       ack_frequency_sent_ = true; | 
 |       auto frame = sent_packet_manager_.GetUpdatedAckFrequencyFrame(); | 
 |       visitor_->SendAckFrequency(frame); | 
 |     } | 
 |   } | 
 |  | 
 |   QuicFrames frames; | 
 |   const bool has_pending_ack = | 
 |       uber_received_packet_manager_ | 
 |           .GetAckTimeout(QuicUtils::GetPacketNumberSpace(encryption_level_)) | 
 |           .IsInitialized(); | 
 |   if (!has_pending_ack && stop_waiting_count_ <= 1) { | 
 |     // No need to send an ACK. | 
 |     return frames; | 
 |   } | 
 |   ResetAckStates(); | 
 |  | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Bundle an ACK opportunistically"; | 
 |   QuicFrame updated_ack_frame = GetUpdatedAckFrame(); | 
 |   QUIC_BUG_IF(quic_bug_12714_23, updated_ack_frame.ack_frame->packets.Empty()) | 
 |       << ENDPOINT << "Attempted to opportunistically bundle an empty " | 
 |       << encryption_level_ << " ACK, " << (has_pending_ack ? "" : "!") | 
 |       << "has_pending_ack, stop_waiting_count_ " << stop_waiting_count_; | 
 |   frames.push_back(updated_ack_frame); | 
 |  | 
 |   if (!no_stop_waiting_frames_) { | 
 |     QuicStopWaitingFrame stop_waiting; | 
 |     PopulateStopWaitingFrame(&stop_waiting); | 
 |     frames.push_back(QuicFrame(stop_waiting)); | 
 |   } | 
 |   return frames; | 
 | } | 
 |  | 
 | bool QuicConnection::CanWrite(HasRetransmittableData retransmittable) { | 
 |   if (!connected_) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (GetQuicReloadableFlag(quic_suppress_write_mid_packet_processing) && | 
 |       version().CanSendCoalescedPackets() && | 
 |       framer_.HasEncrypterOfEncryptionLevel(ENCRYPTION_INITIAL) && | 
 |       framer_.is_processing_packet()) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT(quic_suppress_write_mid_packet_processing); | 
 |     // While we still have initial keys, suppress sending in mid of packet | 
 |     // processing. | 
 |     // TODO(fayang): always suppress sending while in the mid of packet | 
 |     // processing. | 
 |     QUIC_DVLOG(1) << ENDPOINT | 
 |                   << "Suppress sending in the mid of packet processing"; | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (fill_coalesced_packet_) { | 
 |     // Try to coalesce packet, only allow to write when creator is on soft max | 
 |     // packet length. Given the next created packet is going to fill current | 
 |     // coalesced packet, do not check amplification factor. | 
 |     return packet_creator_.HasSoftMaxPacketLength(); | 
 |   } | 
 |  | 
 |   const bool donot_check_amplification_limit_with_pending_timer_credit = | 
 |       GetQuicReloadableFlag( | 
 |           quic_donot_check_amplification_limit_with_pending_timer_credit); | 
 |  | 
 |   if (!donot_check_amplification_limit_with_pending_timer_credit && | 
 |       LimitedByAmplificationFactor()) { | 
 |     // Server is constrained by the amplification restriction. | 
 |     QUIC_CODE_COUNT(quic_throttled_by_amplification_limit); | 
 |     QUIC_DVLOG(1) << ENDPOINT | 
 |                   << "Constrained by amplification restriction to peer address " | 
 |                   << default_path_.peer_address << " bytes received " | 
 |                   << default_path_.bytes_received_before_address_validation | 
 |                   << ", bytes sent" | 
 |                   << default_path_.bytes_sent_before_address_validation; | 
 |     ++stats_.num_amplification_throttling; | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (sent_packet_manager_.pending_timer_transmission_count() > 0) { | 
 |     // Allow sending if there are pending tokens, which occurs when: | 
 |     // 1) firing PTO, | 
 |     // 2) bundling CRYPTO data with ACKs, | 
 |     // 3) coalescing CRYPTO data of higher space. | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (donot_check_amplification_limit_with_pending_timer_credit) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT( | 
 |         quic_donot_check_amplification_limit_with_pending_timer_credit); | 
 |     if (LimitedByAmplificationFactor()) { | 
 |       // Server is constrained by the amplification restriction. | 
 |       QUIC_CODE_COUNT(quic_throttled_by_amplification_limit); | 
 |       QUIC_DVLOG(1) | 
 |           << ENDPOINT | 
 |           << "Constrained by amplification restriction to peer address " | 
 |           << default_path_.peer_address << " bytes received " | 
 |           << default_path_.bytes_received_before_address_validation | 
 |           << ", bytes sent" | 
 |           << default_path_.bytes_sent_before_address_validation; | 
 |       ++stats_.num_amplification_throttling; | 
 |       return false; | 
 |     } | 
 |   } | 
 |  | 
 |   if (HandleWriteBlocked()) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   // Allow acks and probing frames to be sent immediately. | 
 |   if (retransmittable == NO_RETRANSMITTABLE_DATA) { | 
 |     return true; | 
 |   } | 
 |   // If the send alarm is set, wait for it to fire. | 
 |   if (send_alarm_->IsSet()) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   QuicTime now = clock_->Now(); | 
 |   QuicTime::Delta delay = sent_packet_manager_.TimeUntilSend(now); | 
 |   if (delay.IsInfinite()) { | 
 |     send_alarm_->Cancel(); | 
 |     return false; | 
 |   } | 
 |  | 
 |   // Scheduler requires a delay. | 
 |   if (!delay.IsZero()) { | 
 |     if (delay <= release_time_into_future_) { | 
 |       // Required delay is within pace time into future, send now. | 
 |       return true; | 
 |     } | 
 |     // Cannot send packet now because delay is too far in the future. | 
 |     send_alarm_->Update(now + delay, kAlarmGranularity); | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Delaying sending " << delay.ToMilliseconds() | 
 |                   << "ms"; | 
 |     return false; | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | QuicTime QuicConnection::CalculatePacketSentTime() { | 
 |   const QuicTime now = clock_->Now(); | 
 |   if (!supports_release_time_ || per_packet_options_ == nullptr) { | 
 |     // Don't change the release delay. | 
 |     return now; | 
 |   } | 
 |  | 
 |   auto next_release_time_result = sent_packet_manager_.GetNextReleaseTime(); | 
 |  | 
 |   // Release before |now| is impossible. | 
 |   QuicTime next_release_time = | 
 |       std::max(now, next_release_time_result.release_time); | 
 |   per_packet_options_->release_time_delay = next_release_time - now; | 
 |   per_packet_options_->allow_burst = next_release_time_result.allow_burst; | 
 |   return next_release_time; | 
 | } | 
 |  | 
 | bool QuicConnection::WritePacket(SerializedPacket* packet) { | 
 |   if (sent_packet_manager_.GetLargestSentPacket().IsInitialized() && | 
 |       packet->packet_number < sent_packet_manager_.GetLargestSentPacket()) { | 
 |     QUIC_BUG(quic_bug_10511_23) | 
 |         << "Attempt to write packet:" << packet->packet_number | 
 |         << " after:" << sent_packet_manager_.GetLargestSentPacket(); | 
 |     CloseConnection(QUIC_INTERNAL_ERROR, "Packet written out of order.", | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return true; | 
 |   } | 
 |   const bool is_mtu_discovery = QuicUtils::ContainsFrameType( | 
 |       packet->nonretransmittable_frames, MTU_DISCOVERY_FRAME); | 
 |   const SerializedPacketFate fate = packet->fate; | 
 |   // Termination packets are encrypted and saved, so don't exit early. | 
 |   QuicErrorCode error_code = QUIC_NO_ERROR; | 
 |   const bool is_termination_packet = IsTerminationPacket(*packet, &error_code); | 
 |   QuicPacketNumber packet_number = packet->packet_number; | 
 |   QuicPacketLength encrypted_length = packet->encrypted_length; | 
 |   // Termination packets are eventually owned by TimeWaitListManager. | 
 |   // Others are deleted at the end of this call. | 
 |   if (is_termination_packet) { | 
 |     if (termination_packets_ == nullptr) { | 
 |       termination_packets_.reset( | 
 |           new std::vector<std::unique_ptr<QuicEncryptedPacket>>); | 
 |     } | 
 |     // Copy the buffer so it's owned in the future. | 
 |     char* buffer_copy = CopyBuffer(*packet); | 
 |     termination_packets_->emplace_back( | 
 |         new QuicEncryptedPacket(buffer_copy, encrypted_length, true)); | 
 |     if (error_code == QUIC_SILENT_IDLE_TIMEOUT) { | 
 |       QUICHE_DCHECK_EQ(Perspective::IS_SERVER, perspective_); | 
 |       // TODO(fayang): populate histogram indicating the time elapsed from this | 
 |       // connection gets closed to following client packets get received. | 
 |       QUIC_DVLOG(1) << ENDPOINT | 
 |                     << "Added silent connection close to termination packets, " | 
 |                        "num of termination packets: " | 
 |                     << termination_packets_->size(); | 
 |       return true; | 
 |     } | 
 |   } | 
 |  | 
 |   QUICHE_DCHECK_LE(encrypted_length, kMaxOutgoingPacketSize); | 
 |   QUICHE_DCHECK(is_mtu_discovery || | 
 |                 encrypted_length <= packet_creator_.max_packet_length()) | 
 |       << " encrypted_length=" << encrypted_length | 
 |       << " > packet_creator max_packet_length=" | 
 |       << packet_creator_.max_packet_length(); | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Sending packet " << packet_number << " : " | 
 |                 << (IsRetransmittable(*packet) == HAS_RETRANSMITTABLE_DATA | 
 |                         ? "data bearing " | 
 |                         : " ack or probing only ") | 
 |                 << ", encryption level: " << packet->encryption_level | 
 |                 << ", encrypted length:" << encrypted_length | 
 |                 << ", fate: " << fate << " to peer " << packet->peer_address; | 
 |   QUIC_DVLOG(2) << ENDPOINT << packet->encryption_level << " packet number " | 
 |                 << packet_number << " of length " << encrypted_length << ": " | 
 |                 << std::endl | 
 |                 << quiche::QuicheTextUtils::HexDump(absl::string_view( | 
 |                        packet->encrypted_buffer, encrypted_length)); | 
 |  | 
 |   // Measure the RTT from before the write begins to avoid underestimating the | 
 |   // min_rtt_, especially in cases where the thread blocks or gets swapped out | 
 |   // during the WritePacket below. | 
 |   QuicTime packet_send_time = CalculatePacketSentTime(); | 
 |   WriteResult result(WRITE_STATUS_OK, encrypted_length); | 
 |   QuicSocketAddress send_to_address = | 
 |       (send_path_response_) ? packet->peer_address : peer_address(); | 
 |   // Self address is always the default self address on this code path. | 
 |   bool send_on_current_path = send_to_address == peer_address(); | 
 |   switch (fate) { | 
 |     case DISCARD: | 
 |       ++stats_.packets_discarded; | 
 |       return true; | 
 |     case COALESCE: | 
 |       QUIC_BUG_IF(quic_bug_12714_24, | 
 |                   !version().CanSendCoalescedPackets() || coalescing_done_); | 
 |       if (!coalesced_packet_.MaybeCoalescePacket( | 
 |               *packet, self_address(), send_to_address, | 
 |               helper_->GetStreamSendBufferAllocator(), | 
 |               packet_creator_.max_packet_length())) { | 
 |         // Failed to coalesce packet, flush current coalesced packet. | 
 |         if (!FlushCoalescedPacket()) { | 
 |           // Failed to flush coalesced packet, write error has been handled. | 
 |           return false; | 
 |         } | 
 |         if (!coalesced_packet_.MaybeCoalescePacket( | 
 |                 *packet, self_address(), send_to_address, | 
 |                 helper_->GetStreamSendBufferAllocator(), | 
 |                 packet_creator_.max_packet_length())) { | 
 |           // Failed to coalesce packet even it is the only packet, raise a write | 
 |           // error. | 
 |           QUIC_DLOG(ERROR) << ENDPOINT << "Failed to coalesce packet"; | 
 |           result.error_code = WRITE_STATUS_FAILED_TO_COALESCE_PACKET; | 
 |           break; | 
 |         } | 
 |       } | 
 |       if (coalesced_packet_.length() < coalesced_packet_.max_packet_length()) { | 
 |         QUIC_DVLOG(1) << ENDPOINT << "Trying to set soft max packet length to " | 
 |                       << coalesced_packet_.max_packet_length() - | 
 |                              coalesced_packet_.length(); | 
 |         packet_creator_.SetSoftMaxPacketLength( | 
 |             coalesced_packet_.max_packet_length() - coalesced_packet_.length()); | 
 |       } | 
 |       break; | 
 |     case BUFFER: | 
 |       QUIC_DVLOG(1) << ENDPOINT << "Adding packet: " << packet->packet_number | 
 |                     << " to buffered packets"; | 
 |       buffered_packets_.emplace_back(*packet, self_address(), send_to_address); | 
 |       break; | 
 |     case SEND_TO_WRITER: | 
 |       // Stop using coalescer from now on. | 
 |       coalescing_done_ = true; | 
 |       // At this point, packet->release_encrypted_buffer is either nullptr, | 
 |       // meaning |packet->encrypted_buffer| is a stack buffer, or not-nullptr, | 
 |       /// meaning it's a writer-allocated buffer. Note that connectivity probing | 
 |       // packets do not use this function, so setting release_encrypted_buffer | 
 |       // to nullptr will not cause probing packets to be leaked. | 
 |       // | 
 |       // writer_->WritePacket transfers buffer ownership back to the writer. | 
 |       packet->release_encrypted_buffer = nullptr; | 
 |       result = writer_->WritePacket(packet->encrypted_buffer, encrypted_length, | 
 |                                     self_address().host(), send_to_address, | 
 |                                     per_packet_options_); | 
 |       // This is a work around for an issue with linux UDP GSO batch writers. | 
 |       // When sending a GSO packet with 2 segments, if the first segment is | 
 |       // larger than the path MTU, instead of EMSGSIZE, the linux kernel returns | 
 |       // EINVAL, which translates to WRITE_STATUS_ERROR and causes conneciton to | 
 |       // be closed. By manually flush the writer here, the MTU probe is sent in | 
 |       // a normal(non-GSO) packet, so the kernel can return EMSGSIZE and we will | 
 |       // not close the connection. | 
 |       if (is_mtu_discovery && writer_->IsBatchMode()) { | 
 |         result = writer_->Flush(); | 
 |       } | 
 |       break; | 
 |     case LEGACY_VERSION_ENCAPSULATE: { | 
 |       QUICHE_DCHECK(!is_mtu_discovery); | 
 |       QUICHE_DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |       QUICHE_DCHECK_EQ(packet->encryption_level, ENCRYPTION_INITIAL); | 
 |       QUICHE_DCHECK(legacy_version_encapsulation_enabled_); | 
 |       QUICHE_DCHECK(legacy_version_encapsulation_in_progress_); | 
 |       QuicPacketLength encapsulated_length = | 
 |           QuicLegacyVersionEncapsulator::Encapsulate( | 
 |               legacy_version_encapsulation_sni_, | 
 |               absl::string_view(packet->encrypted_buffer, | 
 |                                 packet->encrypted_length), | 
 |               default_path_.server_connection_id, framer_.creation_time(), | 
 |               GetLimitedMaxPacketSize(long_term_mtu_), | 
 |               const_cast<char*>(packet->encrypted_buffer)); | 
 |       if (encapsulated_length != 0) { | 
 |         stats_.sent_legacy_version_encapsulated_packets++; | 
 |         packet->encrypted_length = encapsulated_length; | 
 |         encrypted_length = encapsulated_length; | 
 |         QUIC_DVLOG(2) | 
 |             << ENDPOINT | 
 |             << "Successfully performed Legacy Version Encapsulation on " | 
 |             << packet->encryption_level << " packet number " << packet_number | 
 |             << " of length " << encrypted_length << ": " << std::endl | 
 |             << quiche::QuicheTextUtils::HexDump(absl::string_view( | 
 |                    packet->encrypted_buffer, encrypted_length)); | 
 |       } else { | 
 |         QUIC_BUG(quic_bug_10511_24) | 
 |             << ENDPOINT << "Failed to perform Legacy Version Encapsulation on " | 
 |             << packet->encryption_level << " packet number " << packet_number | 
 |             << " of length " << encrypted_length; | 
 |       } | 
 |       if (!buffered_packets_.empty() || HandleWriteBlocked()) { | 
 |         // Buffer the packet. | 
 |         buffered_packets_.emplace_back(*packet, self_address(), | 
 |                                        send_to_address); | 
 |       } else {  // Send the packet to the writer. | 
 |         // writer_->WritePacket transfers buffer ownership back to the writer. | 
 |         packet->release_encrypted_buffer = nullptr; | 
 |         result = writer_->WritePacket(packet->encrypted_buffer, | 
 |                                       encrypted_length, self_address().host(), | 
 |                                       send_to_address, per_packet_options_); | 
 |       } | 
 |     } break; | 
 |     default: | 
 |       QUICHE_DCHECK(false); | 
 |       break; | 
 |   } | 
 |  | 
 |   QUIC_HISTOGRAM_ENUM( | 
 |       "QuicConnection.WritePacketStatus", result.status, | 
 |       WRITE_STATUS_NUM_VALUES, | 
 |       "Status code returned by writer_->WritePacket() in QuicConnection."); | 
 |  | 
 |   if (IsWriteBlockedStatus(result.status)) { | 
 |     // Ensure the writer is still write blocked, otherwise QUIC may continue | 
 |     // trying to write when it will not be able to. | 
 |     QUICHE_DCHECK(writer_->IsWriteBlocked()); | 
 |     visitor_->OnWriteBlocked(); | 
 |     // If the socket buffers the data, then the packet should not | 
 |     // be queued and sent again, which would result in an unnecessary | 
 |     // duplicate packet being sent.  The helper must call OnCanWrite | 
 |     // when the write completes, and OnWriteError if an error occurs. | 
 |     if (result.status != WRITE_STATUS_BLOCKED_DATA_BUFFERED) { | 
 |       QUIC_DVLOG(1) << ENDPOINT << "Adding packet: " << packet->packet_number | 
 |                     << " to buffered packets"; | 
 |       buffered_packets_.emplace_back(*packet, self_address(), send_to_address); | 
 |     } | 
 |   } | 
 |  | 
 |   // In some cases, an MTU probe can cause EMSGSIZE. This indicates that the | 
 |   // MTU discovery is permanently unsuccessful. | 
 |   if (IsMsgTooBig(result)) { | 
 |     if (is_mtu_discovery) { | 
 |       // When MSG_TOO_BIG is returned, the system typically knows what the | 
 |       // actual MTU is, so there is no need to probe further. | 
 |       // TODO(wub): Reduce max packet size to a safe default, or the actual MTU. | 
 |       QUIC_DVLOG(1) << ENDPOINT | 
 |                     << " MTU probe packet too big, size:" << encrypted_length | 
 |                     << ", long_term_mtu_:" << long_term_mtu_; | 
 |       mtu_discoverer_.Disable(); | 
 |       mtu_discovery_alarm_->Cancel(); | 
 |       // The write failed, but the writer is not blocked, so return true. | 
 |       return true; | 
 |     } | 
 |     if (use_path_validator_ && !send_on_current_path) { | 
 |       QUIC_RELOADABLE_FLAG_COUNT_N(quic_pass_path_response_to_validator, 2, 4); | 
 |       // Only handle MSG_TOO_BIG as error on current path. | 
 |       return true; | 
 |     } | 
 |   } | 
 |  | 
 |   if (IsWriteError(result.status)) { | 
 |     QUIC_LOG_FIRST_N(ERROR, 10) | 
 |         << ENDPOINT << "Failed writing packet " << packet_number << " of " | 
 |         << encrypted_length << " bytes from " << self_address().host() << " to " | 
 |         << send_to_address << ", with error code " << result.error_code | 
 |         << ". long_term_mtu_:" << long_term_mtu_ | 
 |         << ", previous_validated_mtu_:" << previous_validated_mtu_ | 
 |         << ", max_packet_length():" << max_packet_length() | 
 |         << ", is_mtu_discovery:" << is_mtu_discovery; | 
 |     if (MaybeRevertToPreviousMtu()) { | 
 |       return true; | 
 |     } | 
 |  | 
 |     OnWriteError(result.error_code); | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (result.status == WRITE_STATUS_OK) { | 
 |     // packet_send_time is the ideal send time, if allow_burst is true, writer | 
 |     // may have sent it earlier than that. | 
 |     packet_send_time = packet_send_time + result.send_time_offset; | 
 |   } | 
 |  | 
 |   if (IsRetransmittable(*packet) == HAS_RETRANSMITTABLE_DATA && | 
 |       !is_termination_packet) { | 
 |     // Start blackhole/path degrading detections if the sent packet is not | 
 |     // termination packet and contains retransmittable data. | 
 |     // Do not restart detection if detection is in progress indicating no | 
 |     // forward progress has been made since last event (i.e., packet was sent | 
 |     // or new packets were acknowledged). | 
 |     if (!blackhole_detector_.IsDetectionInProgress()) { | 
 |       // Try to start detections if no detection in progress. This could | 
 |       // because either both detections are inactive when sending last packet | 
 |       // or this connection just gets out of quiescence. | 
 |       blackhole_detector_.RestartDetection(GetPathDegradingDeadline(), | 
 |                                            GetNetworkBlackholeDeadline(), | 
 |                                            GetPathMtuReductionDeadline()); | 
 |     } | 
 |     idle_network_detector_.OnPacketSent(packet_send_time, | 
 |                                         sent_packet_manager_.GetPtoDelay()); | 
 |   } | 
 |  | 
 |   MaybeSetMtuAlarm(packet_number); | 
 |   QUIC_DVLOG(1) << ENDPOINT << "time we began writing last sent packet: " | 
 |                 << packet_send_time.ToDebuggingValue(); | 
 |  | 
 |   if (!count_bytes_on_alternative_path_separately_) { | 
 |     if (EnforceAntiAmplificationLimit()) { | 
 |       // Include bytes sent even if they are not in flight. | 
 |       default_path_.bytes_sent_before_address_validation += encrypted_length; | 
 |     } | 
 |   } else { | 
 |     QUIC_CODE_COUNT_N(quic_count_bytes_on_alternative_path_seperately, 2, 5); | 
 |     if (IsDefaultPath(default_path_.self_address, send_to_address)) { | 
 |       if (EnforceAntiAmplificationLimit()) { | 
 |         // Include bytes sent even if they are not in flight. | 
 |         default_path_.bytes_sent_before_address_validation += encrypted_length; | 
 |       } | 
 |     } else { | 
 |       MaybeUpdateBytesSentToAlternativeAddress(send_to_address, | 
 |                                                encrypted_length); | 
 |     } | 
 |   } | 
 |  | 
 |   // Do not measure rtt of this packet if it's not sent on current path. | 
 |   QUIC_DLOG_IF(INFO, !send_on_current_path) | 
 |       << ENDPOINT << " Sent packet " << packet->packet_number | 
 |       << " on a different path with remote address " << send_to_address | 
 |       << " while current path has peer address " << peer_address(); | 
 |   const bool in_flight = sent_packet_manager_.OnPacketSent( | 
 |       packet, packet_send_time, packet->transmission_type, | 
 |       IsRetransmittable(*packet), /*measure_rtt=*/send_on_current_path); | 
 |   QUIC_BUG_IF(quic_bug_12714_25, | 
 |               perspective_ == Perspective::IS_SERVER && | 
 |                   default_enable_5rto_blackhole_detection_ && | 
 |                   blackhole_detector_.IsDetectionInProgress() && | 
 |                   !sent_packet_manager_.HasInFlightPackets()) | 
 |       << ENDPOINT | 
 |       << "Trying to start blackhole detection without no bytes in flight"; | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     if (sent_packet_manager_.unacked_packets().empty()) { | 
 |       QUIC_BUG(quic_bug_10511_25) | 
 |           << "Unacked map is empty right after packet is sent"; | 
 |     } else { | 
 |       debug_visitor_->OnPacketSent( | 
 |           packet->packet_number, packet->encrypted_length, | 
 |           packet->has_crypto_handshake, packet->transmission_type, | 
 |           packet->encryption_level, | 
 |           sent_packet_manager_.unacked_packets() | 
 |               .rbegin() | 
 |               ->retransmittable_frames, | 
 |           packet->nonretransmittable_frames, packet_send_time); | 
 |     } | 
 |   } | 
 |   if (packet->encryption_level == ENCRYPTION_HANDSHAKE) { | 
 |     handshake_packet_sent_ = true; | 
 |   } | 
 |  | 
 |   if (packet->encryption_level == ENCRYPTION_FORWARD_SECURE) { | 
 |     if (!lowest_packet_sent_in_current_key_phase_.IsInitialized()) { | 
 |       QUIC_DLOG(INFO) << ENDPOINT | 
 |                       << "lowest_packet_sent_in_current_key_phase_ = " | 
 |                       << packet_number; | 
 |       lowest_packet_sent_in_current_key_phase_ = packet_number; | 
 |     } | 
 |     if (!is_termination_packet && | 
 |         MaybeHandleAeadConfidentialityLimits(*packet)) { | 
 |       return true; | 
 |     } | 
 |   } | 
 |   if (GetQuicReloadableFlag( | 
 |           quic_donot_rearm_pto_on_application_data_during_handshake)) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT( | 
 |         quic_donot_rearm_pto_on_application_data_during_handshake); | 
 |     if (ShouldSetRetransmissionAlarmOnPacketSent(in_flight, | 
 |                                                  packet->encryption_level)) { | 
 |       SetRetransmissionAlarm(); | 
 |     } | 
 |   } else if (in_flight || !retransmission_alarm_->IsSet()) { | 
 |     SetRetransmissionAlarm(); | 
 |   } | 
 |   SetPingAlarm(); | 
 |   RetirePeerIssuedConnectionIdsNoLongerOnPath(); | 
 |  | 
 |   // The packet number length must be updated after OnPacketSent, because it | 
 |   // may change the packet number length in packet. | 
 |   packet_creator_.UpdatePacketNumberLength( | 
 |       sent_packet_manager_.GetLeastPacketAwaitedByPeer(encryption_level_), | 
 |       sent_packet_manager_.EstimateMaxPacketsInFlight(max_packet_length())); | 
 |  | 
 |   stats_.bytes_sent += result.bytes_written; | 
 |   ++stats_.packets_sent; | 
 |   if (packet->transmission_type != NOT_RETRANSMISSION) { | 
 |     stats_.bytes_retransmitted += result.bytes_written; | 
 |     ++stats_.packets_retransmitted; | 
 |   } | 
 |  | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::MaybeHandleAeadConfidentialityLimits( | 
 |     const SerializedPacket& packet) { | 
 |   if (!version().UsesTls()) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (packet.encryption_level != ENCRYPTION_FORWARD_SECURE) { | 
 |     QUIC_BUG(quic_bug_12714_26) | 
 |         << "MaybeHandleAeadConfidentialityLimits called on non 1-RTT packet"; | 
 |     return false; | 
 |   } | 
 |   if (!lowest_packet_sent_in_current_key_phase_.IsInitialized()) { | 
 |     QUIC_BUG(quic_bug_10511_26) | 
 |         << "lowest_packet_sent_in_current_key_phase_ must be initialized " | 
 |            "before calling MaybeHandleAeadConfidentialityLimits"; | 
 |     return false; | 
 |   } | 
 |  | 
 |   // Calculate the number of packets encrypted from the packet number, which is | 
 |   // simpler than keeping another counter. The packet number space may be | 
 |   // sparse, so this might overcount, but doing a key update earlier than | 
 |   // necessary would only improve security and has negligible cost. | 
 |   if (packet.packet_number < lowest_packet_sent_in_current_key_phase_) { | 
 |     const std::string error_details = | 
 |         absl::StrCat("packet_number(", packet.packet_number.ToString(), | 
 |                      ") < lowest_packet_sent_in_current_key_phase_ (", | 
 |                      lowest_packet_sent_in_current_key_phase_.ToString(), ")"); | 
 |     QUIC_BUG(quic_bug_10511_27) << error_details; | 
 |     CloseConnection(QUIC_INTERNAL_ERROR, error_details, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return true; | 
 |   } | 
 |   const QuicPacketCount num_packets_encrypted_in_current_key_phase = | 
 |       packet.packet_number - lowest_packet_sent_in_current_key_phase_ + 1; | 
 |  | 
 |   const QuicPacketCount confidentiality_limit = | 
 |       framer_.GetOneRttEncrypterConfidentialityLimit(); | 
 |  | 
 |   // Attempt to initiate a key update before reaching the AEAD | 
 |   // confidentiality limit when the number of packets sent in the current | 
 |   // key phase gets within |kKeyUpdateConfidentialityLimitOffset| packets of | 
 |   // the limit, unless overridden by | 
 |   // FLAGS_quic_key_update_confidentiality_limit. | 
 |   constexpr QuicPacketCount kKeyUpdateConfidentialityLimitOffset = 1000; | 
 |   QuicPacketCount key_update_limit = 0; | 
 |   if (confidentiality_limit > kKeyUpdateConfidentialityLimitOffset) { | 
 |     key_update_limit = | 
 |         confidentiality_limit - kKeyUpdateConfidentialityLimitOffset; | 
 |   } | 
 |   const QuicPacketCount key_update_limit_override = | 
 |       GetQuicFlag(FLAGS_quic_key_update_confidentiality_limit); | 
 |   if (key_update_limit_override) { | 
 |     key_update_limit = key_update_limit_override; | 
 |   } | 
 |  | 
 |   QUIC_DVLOG(2) << ENDPOINT << "Checking AEAD confidentiality limits: " | 
 |                 << "num_packets_encrypted_in_current_key_phase=" | 
 |                 << num_packets_encrypted_in_current_key_phase | 
 |                 << " key_update_limit=" << key_update_limit | 
 |                 << " confidentiality_limit=" << confidentiality_limit | 
 |                 << " IsKeyUpdateAllowed()=" << IsKeyUpdateAllowed(); | 
 |  | 
 |   if (num_packets_encrypted_in_current_key_phase >= confidentiality_limit) { | 
 |     // Reached the confidentiality limit without initiating a key update, | 
 |     // must close the connection. | 
 |     const std::string error_details = absl::StrCat( | 
 |         "encrypter confidentiality limit reached: " | 
 |         "num_packets_encrypted_in_current_key_phase=", | 
 |         num_packets_encrypted_in_current_key_phase, | 
 |         " key_update_limit=", key_update_limit, | 
 |         " confidentiality_limit=", confidentiality_limit, | 
 |         " IsKeyUpdateAllowed()=", IsKeyUpdateAllowed()); | 
 |     CloseConnection(QUIC_AEAD_LIMIT_REACHED, error_details, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (IsKeyUpdateAllowed() && | 
 |       num_packets_encrypted_in_current_key_phase >= key_update_limit) { | 
 |     // Approaching the confidentiality limit, initiate key update so that | 
 |     // the next set of keys will be ready for the next packet before the | 
 |     // limit is reached. | 
 |     KeyUpdateReason reason = KeyUpdateReason::kLocalAeadConfidentialityLimit; | 
 |     if (key_update_limit_override) { | 
 |       QUIC_DLOG(INFO) << ENDPOINT | 
 |                       << "reached FLAGS_quic_key_update_confidentiality_limit, " | 
 |                          "initiating key update: " | 
 |                       << "num_packets_encrypted_in_current_key_phase=" | 
 |                       << num_packets_encrypted_in_current_key_phase | 
 |                       << " key_update_limit=" << key_update_limit | 
 |                       << " confidentiality_limit=" << confidentiality_limit; | 
 |       reason = KeyUpdateReason::kLocalKeyUpdateLimitOverride; | 
 |     } else { | 
 |       QUIC_DLOG(INFO) << ENDPOINT | 
 |                       << "approaching AEAD confidentiality limit, " | 
 |                          "initiating key update: " | 
 |                       << "num_packets_encrypted_in_current_key_phase=" | 
 |                       << num_packets_encrypted_in_current_key_phase | 
 |                       << " key_update_limit=" << key_update_limit | 
 |                       << " confidentiality_limit=" << confidentiality_limit; | 
 |     } | 
 |     InitiateKeyUpdate(reason); | 
 |   } | 
 |  | 
 |   return false; | 
 | } | 
 |  | 
 | void QuicConnection::FlushPackets() { | 
 |   if (!connected_) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (!writer_->IsBatchMode()) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (HandleWriteBlocked()) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "FlushPackets called while blocked."; | 
 |     return; | 
 |   } | 
 |  | 
 |   WriteResult result = writer_->Flush(); | 
 |  | 
 |   QUIC_HISTOGRAM_ENUM("QuicConnection.FlushPacketStatus", result.status, | 
 |                       WRITE_STATUS_NUM_VALUES, | 
 |                       "Status code returned by writer_->Flush() in " | 
 |                       "QuicConnection::FlushPackets."); | 
 |  | 
 |   if (HandleWriteBlocked()) { | 
 |     QUICHE_DCHECK_EQ(WRITE_STATUS_BLOCKED, result.status) | 
 |         << "Unexpected flush result:" << result; | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Write blocked in FlushPackets."; | 
 |     return; | 
 |   } | 
 |  | 
 |   if (IsWriteError(result.status) && !MaybeRevertToPreviousMtu()) { | 
 |     OnWriteError(result.error_code); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::IsMsgTooBig(const WriteResult& result) { | 
 |   return (result.status == WRITE_STATUS_MSG_TOO_BIG) || | 
 |          (IsWriteError(result.status) && result.error_code == QUIC_EMSGSIZE); | 
 | } | 
 |  | 
 | bool QuicConnection::ShouldDiscardPacket(EncryptionLevel encryption_level) { | 
 |   if (!connected_) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT | 
 |                     << "Not sending packet as connection is disconnected."; | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE && | 
 |       encryption_level == ENCRYPTION_INITIAL) { | 
 |     // Drop packets that are NULL encrypted since the peer won't accept them | 
 |     // anymore. | 
 |     QUIC_DLOG(INFO) << ENDPOINT | 
 |                     << "Dropping NULL encrypted packet since the connection is " | 
 |                        "forward secure."; | 
 |     return true; | 
 |   } | 
 |  | 
 |   return false; | 
 | } | 
 |  | 
 | QuicTime QuicConnection::GetPathMtuReductionDeadline() const { | 
 |   if (previous_validated_mtu_ == 0) { | 
 |     return QuicTime::Zero(); | 
 |   } | 
 |   QuicTime::Delta delay = sent_packet_manager_.GetMtuReductionDelay( | 
 |       num_rtos_for_blackhole_detection_); | 
 |   if (delay.IsZero()) { | 
 |     return QuicTime::Zero(); | 
 |   } | 
 |   return clock_->ApproximateNow() + delay; | 
 | } | 
 |  | 
 | bool QuicConnection::MaybeRevertToPreviousMtu() { | 
 |   if (previous_validated_mtu_ == 0) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   SetMaxPacketLength(previous_validated_mtu_); | 
 |   mtu_discoverer_.Disable(); | 
 |   mtu_discovery_alarm_->Cancel(); | 
 |   previous_validated_mtu_ = 0; | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::OnWriteError(int error_code) { | 
 |   if (write_error_occurred_) { | 
 |     // A write error already occurred. The connection is being closed. | 
 |     return; | 
 |   } | 
 |   write_error_occurred_ = true; | 
 |  | 
 |   const std::string error_details = absl::StrCat( | 
 |       "Write failed with error: ", error_code, " (", strerror(error_code), ")"); | 
 |   QUIC_LOG_FIRST_N(ERROR, 2) << ENDPOINT << error_details; | 
 |   switch (error_code) { | 
 |     case QUIC_EMSGSIZE: | 
 |       CloseConnection(QUIC_PACKET_WRITE_ERROR, error_details, | 
 |                       ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |       break; | 
 |     default: | 
 |       // We can't send an error as the socket is presumably borked. | 
 |       if (version().HasIetfInvariantHeader()) { | 
 |         QUIC_CODE_COUNT(quic_tear_down_local_connection_on_write_error_ietf); | 
 |       } else { | 
 |         QUIC_CODE_COUNT( | 
 |             quic_tear_down_local_connection_on_write_error_non_ietf); | 
 |       } | 
 |       CloseConnection(QUIC_PACKET_WRITE_ERROR, error_details, | 
 |                       ConnectionCloseBehavior::SILENT_CLOSE); | 
 |   } | 
 | } | 
 |  | 
 | QuicPacketBuffer QuicConnection::GetPacketBuffer() { | 
 |   if (version().CanSendCoalescedPackets() && !coalescing_done_) { | 
 |     // Do not use writer's packet buffer for coalesced packets which may | 
 |     // contain multiple QUIC packets. | 
 |     return {nullptr, nullptr}; | 
 |   } | 
 |   return writer_->GetNextWriteLocation(self_address().host(), peer_address()); | 
 | } | 
 |  | 
 | void QuicConnection::OnSerializedPacket(SerializedPacket serialized_packet) { | 
 |   if (serialized_packet.encrypted_buffer == nullptr) { | 
 |     // We failed to serialize the packet, so close the connection. | 
 |     // Specify that the close is silent, that no packet be sent, so no infinite | 
 |     // loop here. | 
 |     // TODO(ianswett): This is actually an internal error, not an | 
 |     // encryption failure. | 
 |     if (version().HasIetfInvariantHeader()) { | 
 |       QUIC_CODE_COUNT( | 
 |           quic_tear_down_local_connection_on_serialized_packet_ietf); | 
 |     } else { | 
 |       QUIC_CODE_COUNT( | 
 |           quic_tear_down_local_connection_on_serialized_packet_non_ietf); | 
 |     } | 
 |     CloseConnection(QUIC_ENCRYPTION_FAILURE, | 
 |                     "Serialized packet does not have an encrypted buffer.", | 
 |                     ConnectionCloseBehavior::SILENT_CLOSE); | 
 |     return; | 
 |   } | 
 |  | 
 |   if (serialized_packet.retransmittable_frames.empty()) { | 
 |     // Increment consecutive_num_packets_with_no_retransmittable_frames_ if | 
 |     // this packet is a new transmission with no retransmittable frames. | 
 |     ++consecutive_num_packets_with_no_retransmittable_frames_; | 
 |   } else { | 
 |     consecutive_num_packets_with_no_retransmittable_frames_ = 0; | 
 |   } | 
 |   SendOrQueuePacket(std::move(serialized_packet)); | 
 | } | 
 |  | 
 | void QuicConnection::OnUnrecoverableError(QuicErrorCode error, | 
 |                                           const std::string& error_details) { | 
 |   // The packet creator or generator encountered an unrecoverable error: tear | 
 |   // down local connection state immediately. | 
 |   if (version().HasIetfInvariantHeader()) { | 
 |     QUIC_CODE_COUNT( | 
 |         quic_tear_down_local_connection_on_unrecoverable_error_ietf); | 
 |   } else { | 
 |     QUIC_CODE_COUNT( | 
 |         quic_tear_down_local_connection_on_unrecoverable_error_non_ietf); | 
 |   } | 
 |   CloseConnection(error, error_details, ConnectionCloseBehavior::SILENT_CLOSE); | 
 | } | 
 |  | 
 | void QuicConnection::OnCongestionChange() { | 
 |   visitor_->OnCongestionWindowChange(clock_->ApproximateNow()); | 
 |  | 
 |   // Uses the connection's smoothed RTT. If zero, uses initial_rtt. | 
 |   QuicTime::Delta rtt = sent_packet_manager_.GetRttStats()->smoothed_rtt(); | 
 |   if (rtt.IsZero()) { | 
 |     rtt = sent_packet_manager_.GetRttStats()->initial_rtt(); | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnRttChanged(rtt); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnPathMtuIncreased(QuicPacketLength packet_size) { | 
 |   if (packet_size > max_packet_length()) { | 
 |     previous_validated_mtu_ = max_packet_length(); | 
 |     SetMaxPacketLength(packet_size); | 
 |     mtu_discoverer_.OnMaxPacketLengthUpdated(previous_validated_mtu_, | 
 |                                              max_packet_length()); | 
 |   } | 
 | } | 
 |  | 
 | std::unique_ptr<QuicSelfIssuedConnectionIdManager> | 
 | QuicConnection::MakeSelfIssuedConnectionIdManager() { | 
 |   QUICHE_DCHECK((perspective_ == Perspective::IS_CLIENT && | 
 |                  !default_path_.client_connection_id.IsEmpty()) || | 
 |                 (perspective_ == Perspective::IS_SERVER && | 
 |                  !default_path_.server_connection_id.IsEmpty())); | 
 |   return std::make_unique<QuicSelfIssuedConnectionIdManager>( | 
 |       kMinNumOfActiveConnectionIds, | 
 |       perspective_ == Perspective::IS_CLIENT | 
 |           ? default_path_.client_connection_id | 
 |           : default_path_.server_connection_id, | 
 |       clock_, alarm_factory_, this, context()); | 
 | } | 
 |  | 
 | void QuicConnection::MaybeSendConnectionIdToClient() { | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     return; | 
 |   } | 
 |   QUICHE_DCHECK(self_issued_cid_manager_ != nullptr); | 
 |   self_issued_cid_manager_->MaybeSendNewConnectionIds(); | 
 | } | 
 |  | 
 | void QuicConnection::OnHandshakeComplete() { | 
 |   sent_packet_manager_.SetHandshakeConfirmed(); | 
 |   if (connection_migration_use_new_cid_ && | 
 |       perspective_ == Perspective::IS_SERVER && | 
 |       self_issued_cid_manager_ != nullptr) { | 
 |     self_issued_cid_manager_->MaybeSendNewConnectionIds(); | 
 |   } | 
 |   if (send_ack_frequency_on_handshake_completion_ && | 
 |       sent_packet_manager_.CanSendAckFrequency()) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_can_send_ack_frequency, 2, 3); | 
 |     auto ack_frequency_frame = | 
 |         sent_packet_manager_.GetUpdatedAckFrequencyFrame(); | 
 |     // This AckFrequencyFrame is meant to only update the max_ack_delay. Set | 
 |     // packet tolerance to the default value for now. | 
 |     ack_frequency_frame.packet_tolerance = | 
 |         kDefaultRetransmittablePacketsBeforeAck; | 
 |     visitor_->SendAckFrequency(ack_frequency_frame); | 
 |     if (!connected_) { | 
 |       return; | 
 |     } | 
 |   } | 
 |   // This may have changed the retransmission timer, so re-arm it. | 
 |   SetRetransmissionAlarm(); | 
 |   if (default_enable_5rto_blackhole_detection_) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_default_enable_5rto_blackhole_detection2, | 
 |                                  2, 3); | 
 |     OnForwardProgressMade(); | 
 |   } | 
 |   if (!SupportsMultiplePacketNumberSpaces()) { | 
 |     // The client should immediately ack the SHLO to confirm the handshake is | 
 |     // complete with the server. | 
 |     if (perspective_ == Perspective::IS_CLIENT && ack_frame_updated()) { | 
 |       ack_alarm_->Update(clock_->ApproximateNow(), QuicTime::Delta::Zero()); | 
 |     } | 
 |     return; | 
 |   } | 
 |   // Stop sending ack of handshake packet number space. | 
 |   uber_received_packet_manager_.ResetAckStates(ENCRYPTION_HANDSHAKE); | 
 |   // Re-arm ack alarm. | 
 |   ack_alarm_->Update(uber_received_packet_manager_.GetEarliestAckTimeout(), | 
 |                      kAlarmGranularity); | 
 | } | 
 |  | 
 | void QuicConnection::SendOrQueuePacket(SerializedPacket packet) { | 
 |   // The caller of this function is responsible for checking CanWrite(). | 
 |   WritePacket(&packet); | 
 | } | 
 |  | 
 | void QuicConnection::OnPingTimeout() { | 
 |   if (retransmission_alarm_->IsSet() || | 
 |       !visitor_->ShouldKeepConnectionAlive()) { | 
 |     return; | 
 |   } | 
 |   SendPingAtLevel(framer().GetEncryptionLevelToSendApplicationData()); | 
 | } | 
 |  | 
 | void QuicConnection::SendAck() { | 
 |   QUICHE_DCHECK(!SupportsMultiplePacketNumberSpaces()); | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Sending an ACK proactively"; | 
 |   QuicFrames frames; | 
 |   frames.push_back(GetUpdatedAckFrame()); | 
 |   if (!no_stop_waiting_frames_) { | 
 |     QuicStopWaitingFrame stop_waiting; | 
 |     PopulateStopWaitingFrame(&stop_waiting); | 
 |     frames.push_back(QuicFrame(stop_waiting)); | 
 |   } | 
 |   if (!packet_creator_.FlushAckFrame(frames)) { | 
 |     return; | 
 |   } | 
 |   ResetAckStates(); | 
 |   if (!ShouldBundleRetransmittableFrameWithAck()) { | 
 |     return; | 
 |   } | 
 |   consecutive_num_packets_with_no_retransmittable_frames_ = 0; | 
 |   if (packet_creator_.HasPendingRetransmittableFrames() || | 
 |       visitor_->WillingAndAbleToWrite()) { | 
 |     // There are pending retransmittable frames. | 
 |     return; | 
 |   } | 
 |  | 
 |   visitor_->OnAckNeedsRetransmittableFrame(); | 
 | } | 
 |  | 
 | void QuicConnection::OnRetransmissionTimeout() { | 
 |   ScopedRetransmissionTimeoutIndicator indicator(this); | 
 | #ifndef NDEBUG | 
 |   if (sent_packet_manager_.unacked_packets().empty()) { | 
 |     QUICHE_DCHECK(sent_packet_manager_.handshake_mode_disabled()); | 
 |     QUICHE_DCHECK(!IsHandshakeComplete()); | 
 |   } | 
 | #endif | 
 |   if (!connected_) { | 
 |     return; | 
 |   } | 
 |  | 
 |   QuicPacketNumber previous_created_packet_number = | 
 |       packet_creator_.packet_number(); | 
 |   const auto retransmission_mode = | 
 |       sent_packet_manager_.OnRetransmissionTimeout(); | 
 |   if (sent_packet_manager_.skip_packet_number_for_pto() && | 
 |       retransmission_mode == QuicSentPacketManager::PTO_MODE && | 
 |       sent_packet_manager_.pending_timer_transmission_count() == 1) { | 
 |     // Skip a packet number when a single PTO packet is sent to elicit an | 
 |     // immediate ACK. | 
 |     const QuicPacketCount num_packet_numbers_to_skip = 1; | 
 |     packet_creator_.SkipNPacketNumbers( | 
 |         num_packet_numbers_to_skip, | 
 |         sent_packet_manager_.GetLeastPacketAwaitedByPeer(encryption_level_), | 
 |         sent_packet_manager_.EstimateMaxPacketsInFlight(max_packet_length())); | 
 |     previous_created_packet_number += num_packet_numbers_to_skip; | 
 |     if (debug_visitor_ != nullptr) { | 
 |       debug_visitor_->OnNPacketNumbersSkipped(num_packet_numbers_to_skip, | 
 |                                               clock_->Now()); | 
 |     } | 
 |   } | 
 |   if (default_enable_5rto_blackhole_detection_ && | 
 |       !sent_packet_manager_.HasInFlightPackets() && | 
 |       blackhole_detector_.IsDetectionInProgress()) { | 
 |     // Stop detection in quiescence. | 
 |     QUICHE_DCHECK_EQ(QuicSentPacketManager::LOSS_MODE, retransmission_mode); | 
 |     blackhole_detector_.StopDetection(/*permanent=*/false); | 
 |   } | 
 |   WriteIfNotBlocked(); | 
 |  | 
 |   // A write failure can result in the connection being closed, don't attempt to | 
 |   // write further packets, or to set alarms. | 
 |   if (!connected_) { | 
 |     return; | 
 |   } | 
 |  | 
 |   // In the PTO and TLP cases, the SentPacketManager gives the connection the | 
 |   // opportunity to send new data before retransmitting. | 
 |   if (sent_packet_manager_.pto_enabled()) { | 
 |     sent_packet_manager_.MaybeSendProbePackets(); | 
 |   } else if (sent_packet_manager_.MaybeRetransmitTailLossProbe()) { | 
 |     // Send the pending retransmission now that it's been queued. | 
 |     WriteIfNotBlocked(); | 
 |   } | 
 |  | 
 |   if (packet_creator_.packet_number() == previous_created_packet_number && | 
 |       (retransmission_mode == QuicSentPacketManager::TLP_MODE || | 
 |        retransmission_mode == QuicSentPacketManager::RTO_MODE || | 
 |        retransmission_mode == QuicSentPacketManager::PTO_MODE) && | 
 |       !visitor_->WillingAndAbleToWrite()) { | 
 |     // Send PING if timer fires in TLP/RTO/PTO mode but there is no data to | 
 |     // send. | 
 |     QUIC_DLOG(INFO) << ENDPOINT | 
 |                     << "No packet gets sent when timer fires in mode " | 
 |                     << retransmission_mode << ", send PING"; | 
 |     QUICHE_DCHECK_LT(0u, | 
 |                      sent_packet_manager_.pending_timer_transmission_count()); | 
 |     if (SupportsMultiplePacketNumberSpaces()) { | 
 |       // Based on https://datatracker.ietf.org/doc/html/rfc9002#appendix-A.9 | 
 |       PacketNumberSpace packet_number_space; | 
 |       if (sent_packet_manager_ | 
 |               .GetEarliestPacketSentTimeForPto(&packet_number_space) | 
 |               .IsInitialized()) { | 
 |         SendPingAtLevel(QuicUtils::GetEncryptionLevel(packet_number_space)); | 
 |       } else { | 
 |         // The client must PTO when there is nothing in flight if the server | 
 |         // could be blocked from sending by the amplification limit | 
 |         QUICHE_DCHECK_EQ(Perspective::IS_CLIENT, perspective_); | 
 |         if (framer_.HasEncrypterOfEncryptionLevel(ENCRYPTION_HANDSHAKE)) { | 
 |           SendPingAtLevel(ENCRYPTION_HANDSHAKE); | 
 |         } else if (framer_.HasEncrypterOfEncryptionLevel(ENCRYPTION_INITIAL)) { | 
 |           SendPingAtLevel(ENCRYPTION_INITIAL); | 
 |         } else { | 
 |           QUIC_BUG(quic_bug_no_pto) << "PTO fired but nothing was sent."; | 
 |         } | 
 |       } | 
 |     } else { | 
 |       SendPingAtLevel(encryption_level_); | 
 |     } | 
 |   } | 
 |   if (retransmission_mode == QuicSentPacketManager::PTO_MODE) { | 
 |     sent_packet_manager_.AdjustPendingTimerTransmissions(); | 
 |   } | 
 |   if (retransmission_mode != QuicSentPacketManager::LOSS_MODE && | 
 |       retransmission_mode != QuicSentPacketManager::HANDSHAKE_MODE) { | 
 |     // When timer fires in TLP/RTO/PTO mode, ensure 1) at least one packet is | 
 |     // created, or there is data to send and available credit (such that | 
 |     // packets will be sent eventually). | 
 |     QUIC_BUG_IF( | 
 |         quic_bug_12714_27, | 
 |         packet_creator_.packet_number() == previous_created_packet_number && | 
 |             (!visitor_->WillingAndAbleToWrite() || | 
 |              sent_packet_manager_.pending_timer_transmission_count() == 0u)) | 
 |         << "retransmission_mode: " << retransmission_mode | 
 |         << ", packet_number: " << packet_creator_.packet_number() | 
 |         << ", session has data to write: " << visitor_->WillingAndAbleToWrite() | 
 |         << ", writer is blocked: " << writer_->IsWriteBlocked() | 
 |         << ", pending_timer_transmission_count: " | 
 |         << sent_packet_manager_.pending_timer_transmission_count(); | 
 |   } | 
 |  | 
 |   // Ensure the retransmission alarm is always set if there are unacked packets | 
 |   // and nothing waiting to be sent. | 
 |   // This happens if the loss algorithm invokes a timer based loss, but the | 
 |   // packet doesn't need to be retransmitted. | 
 |   if (!HasQueuedData() && !retransmission_alarm_->IsSet()) { | 
 |     SetRetransmissionAlarm(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::SetEncrypter(EncryptionLevel level, | 
 |                                   std::unique_ptr<QuicEncrypter> encrypter) { | 
 |   packet_creator_.SetEncrypter(level, std::move(encrypter)); | 
 | } | 
 |  | 
 | void QuicConnection::RemoveEncrypter(EncryptionLevel level) { | 
 |   framer_.RemoveEncrypter(level); | 
 | } | 
 |  | 
 | void QuicConnection::SetDiversificationNonce( | 
 |     const DiversificationNonce& nonce) { | 
 |   QUICHE_DCHECK_EQ(Perspective::IS_SERVER, perspective_); | 
 |   packet_creator_.SetDiversificationNonce(nonce); | 
 | } | 
 |  | 
 | void QuicConnection::SetDefaultEncryptionLevel(EncryptionLevel level) { | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Setting default encryption level from " | 
 |                 << encryption_level_ << " to " << level; | 
 |   const bool changing_level = level != encryption_level_; | 
 |   if (changing_level && packet_creator_.HasPendingFrames()) { | 
 |     // Flush all queued frames when encryption level changes. | 
 |     ScopedPacketFlusher flusher(this); | 
 |     packet_creator_.FlushCurrentPacket(); | 
 |   } | 
 |   encryption_level_ = level; | 
 |   packet_creator_.set_encryption_level(level); | 
 |   QUIC_BUG_IF(quic_bug_12714_28, !framer_.HasEncrypterOfEncryptionLevel(level)) | 
 |       << ENDPOINT << "Trying to set encryption level to " | 
 |       << EncryptionLevelToString(level) << " while the key is missing"; | 
 |  | 
 |   if (!changing_level) { | 
 |     return; | 
 |   } | 
 |   // The least packet awaited by the peer depends on the encryption level so | 
 |   // we recalculate it here. | 
 |   packet_creator_.UpdatePacketNumberLength( | 
 |       sent_packet_manager_.GetLeastPacketAwaitedByPeer(encryption_level_), | 
 |       sent_packet_manager_.EstimateMaxPacketsInFlight(max_packet_length())); | 
 | } | 
 |  | 
 | void QuicConnection::SetDecrypter(EncryptionLevel level, | 
 |                                   std::unique_ptr<QuicDecrypter> decrypter) { | 
 |   framer_.SetDecrypter(level, std::move(decrypter)); | 
 |  | 
 |   if (!undecryptable_packets_.empty() && | 
 |       !process_undecryptable_packets_alarm_->IsSet()) { | 
 |     process_undecryptable_packets_alarm_->Set(clock_->ApproximateNow()); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::SetAlternativeDecrypter( | 
 |     EncryptionLevel level, | 
 |     std::unique_ptr<QuicDecrypter> decrypter, | 
 |     bool latch_once_used) { | 
 |   framer_.SetAlternativeDecrypter(level, std::move(decrypter), latch_once_used); | 
 |  | 
 |   if (!undecryptable_packets_.empty() && | 
 |       !process_undecryptable_packets_alarm_->IsSet()) { | 
 |     process_undecryptable_packets_alarm_->Set(clock_->ApproximateNow()); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::InstallDecrypter( | 
 |     EncryptionLevel level, | 
 |     std::unique_ptr<QuicDecrypter> decrypter) { | 
 |   if (level == ENCRYPTION_ZERO_RTT) { | 
 |     had_zero_rtt_decrypter_ = true; | 
 |   } | 
 |   framer_.InstallDecrypter(level, std::move(decrypter)); | 
 |   if (!undecryptable_packets_.empty() && | 
 |       !process_undecryptable_packets_alarm_->IsSet()) { | 
 |     process_undecryptable_packets_alarm_->Set(clock_->ApproximateNow()); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::RemoveDecrypter(EncryptionLevel level) { | 
 |   framer_.RemoveDecrypter(level); | 
 | } | 
 |  | 
 | void QuicConnection::DiscardPreviousOneRttKeys() { | 
 |   framer_.DiscardPreviousOneRttKeys(); | 
 | } | 
 |  | 
 | bool QuicConnection::IsKeyUpdateAllowed() const { | 
 |   return support_key_update_for_connection_ && | 
 |          GetLargestAckedPacket().IsInitialized() && | 
 |          lowest_packet_sent_in_current_key_phase_.IsInitialized() && | 
 |          GetLargestAckedPacket() >= lowest_packet_sent_in_current_key_phase_; | 
 | } | 
 |  | 
 | bool QuicConnection::HaveSentPacketsInCurrentKeyPhaseButNoneAcked() const { | 
 |   return lowest_packet_sent_in_current_key_phase_.IsInitialized() && | 
 |          (!GetLargestAckedPacket().IsInitialized() || | 
 |           GetLargestAckedPacket() < lowest_packet_sent_in_current_key_phase_); | 
 | } | 
 |  | 
 | QuicPacketCount QuicConnection::PotentialPeerKeyUpdateAttemptCount() const { | 
 |   return framer_.PotentialPeerKeyUpdateAttemptCount(); | 
 | } | 
 |  | 
 | bool QuicConnection::InitiateKeyUpdate(KeyUpdateReason reason) { | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "InitiateKeyUpdate"; | 
 |   if (!IsKeyUpdateAllowed()) { | 
 |     QUIC_BUG(quic_bug_10511_28) << "key update not allowed"; | 
 |     return false; | 
 |   } | 
 |   return framer_.DoKeyUpdate(reason); | 
 | } | 
 |  | 
 | const QuicDecrypter* QuicConnection::decrypter() const { | 
 |   return framer_.decrypter(); | 
 | } | 
 |  | 
 | const QuicDecrypter* QuicConnection::alternative_decrypter() const { | 
 |   return framer_.alternative_decrypter(); | 
 | } | 
 |  | 
 | void QuicConnection::QueueUndecryptablePacket( | 
 |     const QuicEncryptedPacket& packet, | 
 |     EncryptionLevel decryption_level) { | 
 |   for (const auto& saved_packet : undecryptable_packets_) { | 
 |     if (packet.data() == saved_packet.packet->data() && | 
 |         packet.length() == saved_packet.packet->length()) { | 
 |       QUIC_DVLOG(1) << ENDPOINT << "Not queueing known undecryptable packet"; | 
 |       return; | 
 |     } | 
 |   } | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Queueing undecryptable packet."; | 
 |   undecryptable_packets_.emplace_back(packet, decryption_level, | 
 |                                       last_received_packet_info_); | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     if (!retransmission_alarm_->IsSet() || | 
 |         GetRetransmissionDeadline() < retransmission_alarm_->deadline()) { | 
 |       // Re-arm PTO only if we can make it sooner to speed up recovery. | 
 |       SetRetransmissionAlarm(); | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::MaybeProcessUndecryptablePackets() { | 
 |   process_undecryptable_packets_alarm_->Cancel(); | 
 |  | 
 |   if (undecryptable_packets_.empty() || | 
 |       encryption_level_ == ENCRYPTION_INITIAL) { | 
 |     return; | 
 |   } | 
 |  | 
 |   auto iter = undecryptable_packets_.begin(); | 
 |   while (connected_ && iter != undecryptable_packets_.end()) { | 
 |     // Making sure there is no pending frames when processing next undecrypted | 
 |     // packet because the queued ack frame may change. | 
 |     packet_creator_.FlushCurrentPacket(); | 
 |     if (!connected_) { | 
 |       return; | 
 |     } | 
 |     UndecryptablePacket* undecryptable_packet = &*iter; | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Attempting to process undecryptable packet"; | 
 |     if (debug_visitor_ != nullptr) { | 
 |       debug_visitor_->OnAttemptingToProcessUndecryptablePacket( | 
 |           undecryptable_packet->encryption_level); | 
 |     } | 
 |     bool processed = false; | 
 |     if (reset_per_packet_state_for_undecryptable_packets_) { | 
 |       QUIC_RELOADABLE_FLAG_COUNT_N( | 
 |           quic_reset_per_packet_state_for_undecryptable_packets, 1, 2); | 
 |       last_received_packet_info_ = undecryptable_packet->packet_info; | 
 |       last_size_ = undecryptable_packet->packet->length(); | 
 |       current_packet_data_ = undecryptable_packet->packet->data(); | 
 |       processed = framer_.ProcessPacket(*undecryptable_packet->packet); | 
 |       current_packet_data_ = nullptr; | 
 |     } else { | 
 |       processed = framer_.ProcessPacket(*undecryptable_packet->packet); | 
 |     } | 
 |     if (processed) { | 
 |       QUIC_DVLOG(1) << ENDPOINT << "Processed undecryptable packet!"; | 
 |       iter = undecryptable_packets_.erase(iter); | 
 |       ++stats_.packets_processed; | 
 |       continue; | 
 |     } | 
 |     const bool has_decryption_key = version().KnowsWhichDecrypterToUse() && | 
 |                                     framer_.HasDecrypterOfEncryptionLevel( | 
 |                                         undecryptable_packet->encryption_level); | 
 |     if (framer_.error() == QUIC_DECRYPTION_FAILURE && | 
 |         ShouldEnqueueUnDecryptablePacket(undecryptable_packet->encryption_level, | 
 |                                          has_decryption_key)) { | 
 |       QUIC_DVLOG(1) | 
 |           << ENDPOINT | 
 |           << "Need to attempt to process this undecryptable packet later"; | 
 |       ++iter; | 
 |       continue; | 
 |     } | 
 |     iter = undecryptable_packets_.erase(iter); | 
 |   } | 
 |  | 
 |   // Once handshake is complete, there will be no new keys installed and hence | 
 |   // any undecryptable packets will never be able to be decrypted. | 
 |   bool clear_undecryptable_packets = | 
 |       encryption_level_ == ENCRYPTION_FORWARD_SECURE; | 
 |   if (GetQuicReloadableFlag( | 
 |           quic_clear_undecryptable_packets_on_handshake_complete)) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT( | 
 |         quic_clear_undecryptable_packets_on_handshake_complete); | 
 |     clear_undecryptable_packets = IsHandshakeComplete(); | 
 |   } | 
 |   if (clear_undecryptable_packets) { | 
 |     if (debug_visitor_ != nullptr) { | 
 |       for (const auto& undecryptable_packet : undecryptable_packets_) { | 
 |         debug_visitor_->OnUndecryptablePacket( | 
 |             undecryptable_packet.encryption_level, /*dropped=*/true); | 
 |       } | 
 |     } | 
 |     undecryptable_packets_.clear(); | 
 |   } | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     if (!retransmission_alarm_->IsSet() || undecryptable_packets_.empty() || | 
 |         GetRetransmissionDeadline() < retransmission_alarm_->deadline()) { | 
 |       // 1) If there is still undecryptable packet, only re-arm PTO to make it | 
 |       // sooner to speed up recovery. | 
 |       // 2) If all undecryptable packets get processed, re-arm (which may | 
 |       // postpone) PTO since no immediate recovery is needed. | 
 |       SetRetransmissionAlarm(); | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::QueueCoalescedPacket(const QuicEncryptedPacket& packet) { | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Queueing coalesced packet."; | 
 |   received_coalesced_packets_.push_back(packet.Clone()); | 
 |   ++stats_.num_coalesced_packets_received; | 
 | } | 
 |  | 
 | bool QuicConnection::MaybeProcessCoalescedPackets() { | 
 |   bool processed = false; | 
 |   while (connected_ && !received_coalesced_packets_.empty()) { | 
 |     // Making sure there are no pending frames when processing the next | 
 |     // coalesced packet because the queued ack frame may change. | 
 |     packet_creator_.FlushCurrentPacket(); | 
 |     if (!connected_) { | 
 |       return processed; | 
 |     } | 
 |  | 
 |     std::unique_ptr<QuicEncryptedPacket> packet = | 
 |         std::move(received_coalesced_packets_.front()); | 
 |     received_coalesced_packets_.pop_front(); | 
 |  | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Processing coalesced packet"; | 
 |     if (framer_.ProcessPacket(*packet)) { | 
 |       processed = true; | 
 |       ++stats_.num_coalesced_packets_processed; | 
 |     } else { | 
 |       // If we are unable to decrypt this packet, it might be | 
 |       // because the CHLO or SHLO packet was lost. | 
 |     } | 
 |   } | 
 |   if (processed) { | 
 |     MaybeProcessUndecryptablePackets(); | 
 |     MaybeSendInResponseToPacket(); | 
 |   } | 
 |   return processed; | 
 | } | 
 |  | 
 | void QuicConnection::CloseConnection( | 
 |     QuicErrorCode error, | 
 |     const std::string& details, | 
 |     ConnectionCloseBehavior connection_close_behavior) { | 
 |   CloseConnection(error, NO_IETF_QUIC_ERROR, details, | 
 |                   connection_close_behavior); | 
 | } | 
 |  | 
 | void QuicConnection::CloseConnection( | 
 |     QuicErrorCode error, | 
 |     QuicIetfTransportErrorCodes ietf_error, | 
 |     const std::string& error_details, | 
 |     ConnectionCloseBehavior connection_close_behavior) { | 
 |   QUICHE_DCHECK(!error_details.empty()); | 
 |   if (!connected_) { | 
 |     QUIC_DLOG(INFO) << "Connection is already closed."; | 
 |     return; | 
 |   } | 
 |  | 
 |   if (ietf_error != NO_IETF_QUIC_ERROR) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Closing connection: " << connection_id() | 
 |                     << ", with wire error: " << ietf_error | 
 |                     << ", error: " << QuicErrorCodeToString(error) | 
 |                     << ", and details:  " << error_details; | 
 |   } else { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Closing connection: " << connection_id() | 
 |                     << ", with error: " << QuicErrorCodeToString(error) << " (" | 
 |                     << error << "), and details:  " << error_details; | 
 |   } | 
 |  | 
 |   if (connection_close_behavior != ConnectionCloseBehavior::SILENT_CLOSE) { | 
 |     SendConnectionClosePacket(error, ietf_error, error_details); | 
 |   } | 
 |  | 
 |   TearDownLocalConnectionState(error, ietf_error, error_details, | 
 |                                ConnectionCloseSource::FROM_SELF); | 
 | } | 
 |  | 
 | void QuicConnection::SendConnectionClosePacket( | 
 |     QuicErrorCode error, | 
 |     QuicIetfTransportErrorCodes ietf_error, | 
 |     const std::string& details) { | 
 |   // Always use the current path to send CONNECTION_CLOSE. | 
 |   QuicPacketCreator::ScopedPeerAddressContext context( | 
 |       &packet_creator_, peer_address(), default_path_.client_connection_id, | 
 |       default_path_.server_connection_id, connection_migration_use_new_cid_); | 
 |   if (!SupportsMultiplePacketNumberSpaces()) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Sending connection close packet."; | 
 |     ScopedEncryptionLevelContext context(this, | 
 |                                          GetConnectionCloseEncryptionLevel()); | 
 |     if (version().CanSendCoalescedPackets()) { | 
 |       coalesced_packet_.Clear(); | 
 |     } | 
 |     ClearQueuedPackets(); | 
 |     // If there was a packet write error, write the smallest close possible. | 
 |     ScopedPacketFlusher flusher(this); | 
 |     // Always bundle an ACK with connection close for debugging purpose. | 
 |     bool send_ack = error != QUIC_PACKET_WRITE_ERROR && | 
 |                     !uber_received_packet_manager_.IsAckFrameEmpty( | 
 |                         QuicUtils::GetPacketNumberSpace(encryption_level_)); | 
 |     if (GetQuicReloadableFlag(quic_single_ack_in_packet2)) { | 
 |       QUIC_RELOADABLE_FLAG_COUNT_N(quic_single_ack_in_packet2, 1, 2); | 
 |       send_ack = !packet_creator_.has_ack() && send_ack; | 
 |     } | 
 |     if (send_ack) { | 
 |       SendAck(); | 
 |     } | 
 |     QuicConnectionCloseFrame* frame; | 
 |  | 
 |     frame = new QuicConnectionCloseFrame(transport_version(), error, ietf_error, | 
 |                                          details, | 
 |                                          framer_.current_received_frame_type()); | 
 |     packet_creator_.ConsumeRetransmittableControlFrame(QuicFrame(frame)); | 
 |     packet_creator_.FlushCurrentPacket(); | 
 |     if (version().CanSendCoalescedPackets()) { | 
 |       FlushCoalescedPacket(); | 
 |     } | 
 |     ClearQueuedPackets(); | 
 |     return; | 
 |   } | 
 |   ScopedPacketFlusher flusher(this); | 
 |  | 
 |   // Now that the connection is being closed, discard any unsent packets | 
 |   // so the only packets to be sent will be connection close packets. | 
 |   if (version().CanSendCoalescedPackets()) { | 
 |     coalesced_packet_.Clear(); | 
 |   } | 
 |   ClearQueuedPackets(); | 
 |  | 
 |   for (EncryptionLevel level : | 
 |        {ENCRYPTION_INITIAL, ENCRYPTION_HANDSHAKE, ENCRYPTION_ZERO_RTT, | 
 |         ENCRYPTION_FORWARD_SECURE}) { | 
 |     if (!framer_.HasEncrypterOfEncryptionLevel(level)) { | 
 |       continue; | 
 |     } | 
 |     QUIC_DLOG(INFO) << ENDPOINT | 
 |                     << "Sending connection close packet at level: " << level; | 
 |     ScopedEncryptionLevelContext context(this, level); | 
 |     // Bundle an ACK of the corresponding packet number space for debugging | 
 |     // purpose. | 
 |     bool send_ack = error != QUIC_PACKET_WRITE_ERROR && | 
 |                     !uber_received_packet_manager_.IsAckFrameEmpty( | 
 |                         QuicUtils::GetPacketNumberSpace(encryption_level_)); | 
 |     if (GetQuicReloadableFlag(quic_single_ack_in_packet2)) { | 
 |       QUIC_RELOADABLE_FLAG_COUNT_N(quic_single_ack_in_packet2, 2, 2); | 
 |       send_ack = !packet_creator_.has_ack() && send_ack; | 
 |     } | 
 |     if (send_ack) { | 
 |       QuicFrames frames; | 
 |       frames.push_back(GetUpdatedAckFrame()); | 
 |       packet_creator_.FlushAckFrame(frames); | 
 |     } | 
 |  | 
 |     if (level == ENCRYPTION_FORWARD_SECURE && | 
 |         perspective_ == Perspective::IS_SERVER) { | 
 |       visitor_->BeforeConnectionCloseSent(); | 
 |     } | 
 |  | 
 |     auto* frame = new QuicConnectionCloseFrame( | 
 |         transport_version(), error, ietf_error, details, | 
 |         framer_.current_received_frame_type()); | 
 |     packet_creator_.ConsumeRetransmittableControlFrame(QuicFrame(frame)); | 
 |     packet_creator_.FlushCurrentPacket(); | 
 |   } | 
 |   if (version().CanSendCoalescedPackets()) { | 
 |     FlushCoalescedPacket(); | 
 |   } | 
 |   // Since the connection is closing, if the connection close packets were not | 
 |   // sent, then they should be discarded. | 
 |   ClearQueuedPackets(); | 
 | } | 
 |  | 
 | void QuicConnection::TearDownLocalConnectionState( | 
 |     QuicErrorCode error, | 
 |     QuicIetfTransportErrorCodes ietf_error, | 
 |     const std::string& error_details, | 
 |     ConnectionCloseSource source) { | 
 |   QuicConnectionCloseFrame frame(transport_version(), error, ietf_error, | 
 |                                  error_details, | 
 |                                  framer_.current_received_frame_type()); | 
 |   return TearDownLocalConnectionState(frame, source); | 
 | } | 
 |  | 
 | void QuicConnection::TearDownLocalConnectionState( | 
 |     const QuicConnectionCloseFrame& frame, | 
 |     ConnectionCloseSource source) { | 
 |   if (!connected_) { | 
 |     QUIC_DLOG(INFO) << "Connection is already closed."; | 
 |     return; | 
 |   } | 
 |  | 
 |   // If we are using a batch writer, flush packets queued in it, if any. | 
 |   FlushPackets(); | 
 |   connected_ = false; | 
 |   QUICHE_DCHECK(visitor_ != nullptr); | 
 |   visitor_->OnConnectionClosed(frame, source); | 
 |   // LossDetectionTunerInterface::Finish() may be called from | 
 |   // sent_packet_manager_.OnConnectionClosed. Which may require the session to | 
 |   // finish its business first. | 
 |   sent_packet_manager_.OnConnectionClosed(); | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnConnectionClosed(frame, source); | 
 |   } | 
 |   // Cancel the alarms so they don't trigger any action now that the | 
 |   // connection is closed. | 
 |   CancelAllAlarms(); | 
 |   if (use_path_validator_) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_pass_path_response_to_validator, 3, 4); | 
 |     CancelPathValidation(); | 
 |   } | 
 |   peer_issued_cid_manager_.reset(); | 
 |   self_issued_cid_manager_.reset(); | 
 | } | 
 |  | 
 | void QuicConnection::CancelAllAlarms() { | 
 |   QUIC_DVLOG(1) << "Cancelling all QuicConnection alarms."; | 
 |  | 
 |   ack_alarm_->PermanentCancel(); | 
 |   ping_alarm_->PermanentCancel(); | 
 |   retransmission_alarm_->PermanentCancel(); | 
 |   send_alarm_->PermanentCancel(); | 
 |   mtu_discovery_alarm_->PermanentCancel(); | 
 |   process_undecryptable_packets_alarm_->PermanentCancel(); | 
 |   discard_previous_one_rtt_keys_alarm_->PermanentCancel(); | 
 |   discard_zero_rtt_decryption_keys_alarm_->PermanentCancel(); | 
 |   blackhole_detector_.StopDetection(/*permanent=*/true); | 
 |   idle_network_detector_.StopDetection(); | 
 | } | 
 |  | 
 | QuicByteCount QuicConnection::max_packet_length() const { | 
 |   return packet_creator_.max_packet_length(); | 
 | } | 
 |  | 
 | void QuicConnection::SetMaxPacketLength(QuicByteCount length) { | 
 |   long_term_mtu_ = length; | 
 |   stats_.max_egress_mtu = std::max(stats_.max_egress_mtu, long_term_mtu_); | 
 |   MaybeUpdatePacketCreatorMaxPacketLengthAndPadding(); | 
 | } | 
 |  | 
 | bool QuicConnection::HasQueuedData() const { | 
 |   return packet_creator_.HasPendingFrames() || !buffered_packets_.empty(); | 
 | } | 
 |  | 
 | void QuicConnection::SetNetworkTimeouts(QuicTime::Delta handshake_timeout, | 
 |                                         QuicTime::Delta idle_timeout) { | 
 |   QUIC_BUG_IF(quic_bug_12714_29, idle_timeout > handshake_timeout) | 
 |       << "idle_timeout:" << idle_timeout.ToMilliseconds() | 
 |       << " handshake_timeout:" << handshake_timeout.ToMilliseconds(); | 
 |   // Adjust the idle timeout on client and server to prevent clients from | 
 |   // sending requests to servers which have already closed the connection. | 
 |   if (perspective_ == Perspective::IS_SERVER) { | 
 |     idle_timeout = idle_timeout + QuicTime::Delta::FromSeconds(3); | 
 |   } else if (idle_timeout > QuicTime::Delta::FromSeconds(1)) { | 
 |     idle_timeout = idle_timeout - QuicTime::Delta::FromSeconds(1); | 
 |   } | 
 |   idle_network_detector_.SetTimeouts(handshake_timeout, idle_timeout); | 
 | } | 
 |  | 
 | void QuicConnection::SetPingAlarm() { | 
 |   if (!connected_) { | 
 |     return; | 
 |   } | 
 |   if (perspective_ == Perspective::IS_SERVER && | 
 |       initial_retransmittable_on_wire_timeout_.IsInfinite()) { | 
 |     // The PING alarm exists to support two features: | 
 |     // 1) clients send PINGs every 15s to prevent NAT timeouts, | 
 |     // 2) both clients and servers can send retransmittable on the wire PINGs | 
 |     // (ROWP) while ShouldKeepConnectionAlive is true and there is no packets in | 
 |     // flight. | 
 |     return; | 
 |   } | 
 |   if (!visitor_->ShouldKeepConnectionAlive()) { | 
 |     ping_alarm_->Cancel(); | 
 |     // Don't send a ping unless the application (ie: HTTP/3) says to, usually | 
 |     // because it is expecting a response from the server. | 
 |     return; | 
 |   } | 
 |   if (initial_retransmittable_on_wire_timeout_.IsInfinite() || | 
 |       sent_packet_manager_.HasInFlightPackets() || | 
 |       retransmittable_on_wire_ping_count_ > | 
 |           GetQuicFlag(FLAGS_quic_max_retransmittable_on_wire_ping_count)) { | 
 |     if (perspective_ == Perspective::IS_CLIENT) { | 
 |       // Clients send 15s PINGs to avoid NATs from timing out. | 
 |       ping_alarm_->Update(clock_->ApproximateNow() + ping_timeout_, | 
 |                           QuicTime::Delta::FromSeconds(1)); | 
 |     } else { | 
 |       // Servers do not send 15s PINGs. | 
 |       ping_alarm_->Cancel(); | 
 |     } | 
 |     return; | 
 |   } | 
 |   QUICHE_DCHECK_LT(initial_retransmittable_on_wire_timeout_, ping_timeout_); | 
 |   QuicTime::Delta retransmittable_on_wire_timeout = | 
 |       initial_retransmittable_on_wire_timeout_; | 
 |   int max_aggressive_retransmittable_on_wire_ping_count = | 
 |       GetQuicFlag(FLAGS_quic_max_aggressive_retransmittable_on_wire_ping_count); | 
 |   QUICHE_DCHECK_LE(0, max_aggressive_retransmittable_on_wire_ping_count); | 
 |   if (consecutive_retransmittable_on_wire_ping_count_ > | 
 |       max_aggressive_retransmittable_on_wire_ping_count) { | 
 |     // Exponentially back off the timeout if the number of consecutive | 
 |     // retransmittable on wire pings has exceeds the allowance. | 
 |     int shift = consecutive_retransmittable_on_wire_ping_count_ - | 
 |                 max_aggressive_retransmittable_on_wire_ping_count; | 
 |     retransmittable_on_wire_timeout = | 
 |         initial_retransmittable_on_wire_timeout_ * (1 << shift); | 
 |   } | 
 |   // If it's already set to an earlier time, then don't update it. | 
 |   if (ping_alarm_->IsSet() && | 
 |       ping_alarm_->deadline() < | 
 |           clock_->ApproximateNow() + retransmittable_on_wire_timeout) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (retransmittable_on_wire_timeout < ping_timeout_) { | 
 |     // Use a shorter timeout if there are open streams, but nothing on the wire. | 
 |     ping_alarm_->Update( | 
 |         clock_->ApproximateNow() + retransmittable_on_wire_timeout, | 
 |         kAlarmGranularity); | 
 |     if (max_aggressive_retransmittable_on_wire_ping_count != 0) { | 
 |       consecutive_retransmittable_on_wire_ping_count_++; | 
 |     } | 
 |     retransmittable_on_wire_ping_count_++; | 
 |     return; | 
 |   } | 
 |  | 
 |   ping_alarm_->Update(clock_->ApproximateNow() + ping_timeout_, | 
 |                       kAlarmGranularity); | 
 | } | 
 |  | 
 | void QuicConnection::SetRetransmissionAlarm() { | 
 |   if (!connected_) { | 
 |     if (retransmission_alarm_->IsSet()) { | 
 |       QUIC_BUG(quic_bug_10511_29) | 
 |           << ENDPOINT << "Retransmission alarm is set while disconnected"; | 
 |       retransmission_alarm_->Cancel(); | 
 |     } | 
 |     return; | 
 |   } | 
 |   if (packet_creator_.PacketFlusherAttached()) { | 
 |     pending_retransmission_alarm_ = true; | 
 |     return; | 
 |   } | 
 |   if (LimitedByAmplificationFactor()) { | 
 |     // Do not set retransmission timer if connection is anti-amplification limit | 
 |     // throttled. Otherwise, nothing can be sent when timer fires. | 
 |     retransmission_alarm_->Cancel(); | 
 |     return; | 
 |   } | 
 |  | 
 |   retransmission_alarm_->Update(GetRetransmissionDeadline(), kAlarmGranularity); | 
 | } | 
 |  | 
 | void QuicConnection::MaybeSetMtuAlarm(QuicPacketNumber sent_packet_number) { | 
 |   if (mtu_discovery_alarm_->IsSet() || | 
 |       !mtu_discoverer_.ShouldProbeMtu(sent_packet_number)) { | 
 |     return; | 
 |   } | 
 |   mtu_discovery_alarm_->Set(clock_->ApproximateNow()); | 
 | } | 
 |  | 
 | QuicConnection::ScopedPacketFlusher::ScopedPacketFlusher( | 
 |     QuicConnection* connection) | 
 |     : connection_(connection), | 
 |       flush_and_set_pending_retransmission_alarm_on_delete_(false), | 
 |       handshake_packet_sent_(connection != nullptr && | 
 |                              connection->handshake_packet_sent_) { | 
 |   if (connection_ == nullptr) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (!connection_->packet_creator_.PacketFlusherAttached()) { | 
 |     flush_and_set_pending_retransmission_alarm_on_delete_ = true; | 
 |     connection->packet_creator_.AttachPacketFlusher(); | 
 |   } | 
 | } | 
 |  | 
 | QuicConnection::ScopedPacketFlusher::~ScopedPacketFlusher() { | 
 |   if (connection_ == nullptr || !connection_->connected()) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (flush_and_set_pending_retransmission_alarm_on_delete_) { | 
 |     const QuicTime ack_timeout = | 
 |         connection_->uber_received_packet_manager_.GetEarliestAckTimeout(); | 
 |     if (ack_timeout.IsInitialized()) { | 
 |       if (ack_timeout <= connection_->clock_->ApproximateNow() && | 
 |           !connection_->CanWrite(NO_RETRANSMITTABLE_DATA)) { | 
 |         // Cancel ACK alarm if connection is write blocked, and ACK will be | 
 |         // sent when connection gets unblocked. | 
 |         connection_->ack_alarm_->Cancel(); | 
 |       } else if (!connection_->ack_alarm_->IsSet() || | 
 |                  connection_->ack_alarm_->deadline() > ack_timeout) { | 
 |         connection_->ack_alarm_->Update(ack_timeout, QuicTime::Delta::Zero()); | 
 |       } | 
 |     } | 
 |     if (connection_->ack_alarm_->IsSet() && | 
 |         connection_->ack_alarm_->deadline() <= | 
 |             connection_->clock_->ApproximateNow()) { | 
 |       // An ACK needs to be sent right now. This ACK did not get bundled | 
 |       // because either there was no data to write or packets were marked as | 
 |       // received after frames were queued in the generator. | 
 |       if (connection_->send_alarm_->IsSet() && | 
 |           connection_->send_alarm_->deadline() <= | 
 |               connection_->clock_->ApproximateNow()) { | 
 |         // If send alarm will go off soon, let send alarm send the ACK. | 
 |         connection_->ack_alarm_->Cancel(); | 
 |       } else if (connection_->SupportsMultiplePacketNumberSpaces()) { | 
 |         connection_->SendAllPendingAcks(); | 
 |       } else { | 
 |         connection_->SendAck(); | 
 |       } | 
 |     } | 
 |     connection_->packet_creator_.Flush(); | 
 |     if (connection_->version().CanSendCoalescedPackets()) { | 
 |       connection_->MaybeCoalescePacketOfHigherSpace(); | 
 |       connection_->FlushCoalescedPacket(); | 
 |     } | 
 |     connection_->FlushPackets(); | 
 |     if (!handshake_packet_sent_ && connection_->handshake_packet_sent_) { | 
 |       // This would cause INITIAL key to be dropped. Drop keys here to avoid | 
 |       // missing the write keys in the middle of writing. | 
 |       connection_->visitor_->OnHandshakePacketSent(); | 
 |     } | 
 |     // Reset transmission type. | 
 |     connection_->SetTransmissionType(NOT_RETRANSMISSION); | 
 |  | 
 |     // Once all transmissions are done, check if there is any outstanding data | 
 |     // to send and notify the congestion controller if not. | 
 |     // | 
 |     // Note that this means that the application limited check will happen as | 
 |     // soon as the last flusher gets destroyed, which is typically after a | 
 |     // single stream write is finished.  This means that if all the data from a | 
 |     // single write goes through the connection, the application-limited signal | 
 |     // will fire even if the caller does a write operation immediately after. | 
 |     // There are two important approaches to remedy this situation: | 
 |     // (1) Instantiate ScopedPacketFlusher before performing multiple subsequent | 
 |     //     writes, thus deferring this check until all writes are done. | 
 |     // (2) Write data in chunks sufficiently large so that they cause the | 
 |     //     connection to be limited by the congestion control.  Typically, this | 
 |     //     would mean writing chunks larger than the product of the current | 
 |     //     pacing rate and the pacer granularity.  So, for instance, if the | 
 |     //     pacing rate of the connection is 1 Gbps, and the pacer granularity is | 
 |     //     1 ms, the caller should send at least 125k bytes in order to not | 
 |     //     be marked as application-limited. | 
 |     connection_->CheckIfApplicationLimited(); | 
 |  | 
 |     if (connection_->pending_retransmission_alarm_) { | 
 |       connection_->SetRetransmissionAlarm(); | 
 |       connection_->pending_retransmission_alarm_ = false; | 
 |     } | 
 |   } | 
 |   QUICHE_DCHECK_EQ(flush_and_set_pending_retransmission_alarm_on_delete_, | 
 |                    !connection_->packet_creator_.PacketFlusherAttached()); | 
 | } | 
 |  | 
 | QuicConnection::ScopedEncryptionLevelContext::ScopedEncryptionLevelContext( | 
 |     QuicConnection* connection, | 
 |     EncryptionLevel encryption_level) | 
 |     : connection_(connection), latched_encryption_level_(ENCRYPTION_INITIAL) { | 
 |   if (connection_ == nullptr) { | 
 |     return; | 
 |   } | 
 |   latched_encryption_level_ = connection_->encryption_level_; | 
 |   connection_->SetDefaultEncryptionLevel(encryption_level); | 
 | } | 
 |  | 
 | QuicConnection::ScopedEncryptionLevelContext::~ScopedEncryptionLevelContext() { | 
 |   if (connection_ == nullptr || !connection_->connected_) { | 
 |     return; | 
 |   } | 
 |   connection_->SetDefaultEncryptionLevel(latched_encryption_level_); | 
 | } | 
 |  | 
 | QuicConnection::BufferedPacket::BufferedPacket( | 
 |     const SerializedPacket& packet, | 
 |     const QuicSocketAddress& self_address, | 
 |     const QuicSocketAddress& peer_address) | 
 |     : encrypted_buffer(CopyBuffer(packet), packet.encrypted_length), | 
 |       self_address(self_address), | 
 |       peer_address(peer_address) {} | 
 |  | 
 | QuicConnection::BufferedPacket::BufferedPacket( | 
 |     char* encrypted_buffer, | 
 |     QuicPacketLength encrypted_length, | 
 |     const QuicSocketAddress& self_address, | 
 |     const QuicSocketAddress& peer_address) | 
 |     : encrypted_buffer(CopyBuffer(encrypted_buffer, encrypted_length), | 
 |                        encrypted_length), | 
 |       self_address(self_address), | 
 |       peer_address(peer_address) {} | 
 |  | 
 | QuicConnection::BufferedPacket::~BufferedPacket() { | 
 |   delete[] encrypted_buffer.data(); | 
 | } | 
 |  | 
 | HasRetransmittableData QuicConnection::IsRetransmittable( | 
 |     const SerializedPacket& packet) { | 
 |   // Retransmitted packets retransmittable frames are owned by the unacked | 
 |   // packet map, but are not present in the serialized packet. | 
 |   if (packet.transmission_type != NOT_RETRANSMISSION || | 
 |       !packet.retransmittable_frames.empty()) { | 
 |     return HAS_RETRANSMITTABLE_DATA; | 
 |   } else { | 
 |     return NO_RETRANSMITTABLE_DATA; | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::IsTerminationPacket(const SerializedPacket& packet, | 
 |                                          QuicErrorCode* error_code) { | 
 |   if (packet.retransmittable_frames.empty()) { | 
 |     return false; | 
 |   } | 
 |   for (const QuicFrame& frame : packet.retransmittable_frames) { | 
 |     if (frame.type == CONNECTION_CLOSE_FRAME) { | 
 |       *error_code = frame.connection_close_frame->quic_error_code; | 
 |       return true; | 
 |     } | 
 |   } | 
 |   return false; | 
 | } | 
 |  | 
 | void QuicConnection::SetMtuDiscoveryTarget(QuicByteCount target) { | 
 |   QUIC_DVLOG(2) << ENDPOINT << "SetMtuDiscoveryTarget: " << target; | 
 |   mtu_discoverer_.Disable(); | 
 |   mtu_discoverer_.Enable(max_packet_length(), GetLimitedMaxPacketSize(target)); | 
 | } | 
 |  | 
 | QuicByteCount QuicConnection::GetLimitedMaxPacketSize( | 
 |     QuicByteCount suggested_max_packet_size) { | 
 |   if (!peer_address().IsInitialized()) { | 
 |     QUIC_BUG(quic_bug_10511_30) | 
 |         << "Attempted to use a connection without a valid peer address"; | 
 |     return suggested_max_packet_size; | 
 |   } | 
 |  | 
 |   const QuicByteCount writer_limit = writer_->GetMaxPacketSize(peer_address()); | 
 |  | 
 |   QuicByteCount max_packet_size = suggested_max_packet_size; | 
 |   if (max_packet_size > writer_limit) { | 
 |     max_packet_size = writer_limit; | 
 |   } | 
 |   if (max_packet_size > peer_max_packet_size_) { | 
 |     max_packet_size = peer_max_packet_size_; | 
 |   } | 
 |   if (max_packet_size > kMaxOutgoingPacketSize) { | 
 |     max_packet_size = kMaxOutgoingPacketSize; | 
 |   } | 
 |   return max_packet_size; | 
 | } | 
 |  | 
 | void QuicConnection::SendMtuDiscoveryPacket(QuicByteCount target_mtu) { | 
 |   // Currently, this limit is ensured by the caller. | 
 |   QUICHE_DCHECK_EQ(target_mtu, GetLimitedMaxPacketSize(target_mtu)); | 
 |  | 
 |   // Send the probe. | 
 |   packet_creator_.GenerateMtuDiscoveryPacket(target_mtu); | 
 | } | 
 |  | 
 | // TODO(zhongyi): change this method to generate a connectivity probing packet | 
 | // and let the caller to call writer to write the packet and handle write | 
 | // status. | 
 | bool QuicConnection::SendConnectivityProbingPacket( | 
 |     QuicPacketWriter* probing_writer, | 
 |     const QuicSocketAddress& peer_address) { | 
 |   return SendGenericPathProbePacket(probing_writer, peer_address, | 
 |                                     /* is_response= */ false); | 
 | } | 
 |  | 
 | void QuicConnection::SendConnectivityProbingResponsePacket( | 
 |     const QuicSocketAddress& peer_address) { | 
 |   SendGenericPathProbePacket(nullptr, peer_address, | 
 |                              /* is_response= */ true); | 
 | } | 
 |  | 
 | bool QuicConnection::SendGenericPathProbePacket( | 
 |     QuicPacketWriter* probing_writer, | 
 |     const QuicSocketAddress& peer_address, | 
 |     bool is_response) { | 
 |   QUICHE_DCHECK(peer_address.IsInitialized()); | 
 |   if (!connected_) { | 
 |     QUIC_BUG(quic_bug_10511_31) | 
 |         << "Not sending connectivity probing packet as connection is " | 
 |         << "disconnected."; | 
 |     return false; | 
 |   } | 
 |   if (perspective_ == Perspective::IS_SERVER && probing_writer == nullptr) { | 
 |     // Server can use default packet writer to write packet. | 
 |     probing_writer = writer_; | 
 |   } | 
 |   QUICHE_DCHECK(probing_writer); | 
 |  | 
 |   if (probing_writer->IsWriteBlocked()) { | 
 |     QUIC_DLOG(INFO) | 
 |         << ENDPOINT | 
 |         << "Writer blocked when sending connectivity probing packet."; | 
 |     if (probing_writer == writer_) { | 
 |       // Visitor should not be write blocked if the probing writer is not the | 
 |       // default packet writer. | 
 |       visitor_->OnWriteBlocked(); | 
 |     } | 
 |     return true; | 
 |   } | 
 |  | 
 |   QUIC_DLOG(INFO) << ENDPOINT | 
 |                   << "Sending path probe packet for connection_id = " | 
 |                   << default_path_.server_connection_id; | 
 |  | 
 |   std::unique_ptr<SerializedPacket> probing_packet; | 
 |   if (!version().HasIetfQuicFrames()) { | 
 |     // Non-IETF QUIC, generate a padded ping regardless of whether this is a | 
 |     // request or a response. | 
 |     probing_packet = packet_creator_.SerializeConnectivityProbingPacket(); | 
 |   } else if (is_response) { | 
 |     QUICHE_DCHECK(!send_path_response_); | 
 |     // IETF QUIC path response. | 
 |     // Respond to path probe request using IETF QUIC PATH_RESPONSE frame. | 
 |     probing_packet = | 
 |         packet_creator_.SerializePathResponseConnectivityProbingPacket( | 
 |             received_path_challenge_payloads_, | 
 |             /*is_padded=*/false); | 
 |     received_path_challenge_payloads_.clear(); | 
 |   } else { | 
 |     // IETF QUIC path challenge. | 
 |     // Send a path probe request using IETF QUIC PATH_CHALLENGE frame. | 
 |     transmitted_connectivity_probe_payload_ = | 
 |         std::make_unique<QuicPathFrameBuffer>(); | 
 |     random_generator_->RandBytes(transmitted_connectivity_probe_payload_.get(), | 
 |                                  sizeof(QuicPathFrameBuffer)); | 
 |     probing_packet = | 
 |         packet_creator_.SerializePathChallengeConnectivityProbingPacket( | 
 |             *transmitted_connectivity_probe_payload_); | 
 |     if (!probing_packet) { | 
 |       transmitted_connectivity_probe_payload_ = nullptr; | 
 |     } | 
 |   } | 
 |   QUICHE_DCHECK_EQ(IsRetransmittable(*probing_packet), NO_RETRANSMITTABLE_DATA); | 
 |   return WritePacketUsingWriter(std::move(probing_packet), probing_writer, | 
 |                                 self_address(), peer_address, | 
 |                                 /*measure_rtt=*/true); | 
 | } | 
 |  | 
 | bool QuicConnection::WritePacketUsingWriter( | 
 |     std::unique_ptr<SerializedPacket> packet, | 
 |     QuicPacketWriter* writer, | 
 |     const QuicSocketAddress& self_address, | 
 |     const QuicSocketAddress& peer_address, | 
 |     bool measure_rtt) { | 
 |   const QuicTime packet_send_time = clock_->Now(); | 
 |   QUIC_DVLOG(2) << ENDPOINT | 
 |                 << "Sending path probe packet for server connection ID " | 
 |                 << default_path_.server_connection_id << std::endl | 
 |                 << quiche::QuicheTextUtils::HexDump(absl::string_view( | 
 |                        packet->encrypted_buffer, packet->encrypted_length)); | 
 |   WriteResult result = writer->WritePacket( | 
 |       packet->encrypted_buffer, packet->encrypted_length, self_address.host(), | 
 |       peer_address, per_packet_options_); | 
 |  | 
 |   // If using a batch writer and the probing packet is buffered, flush it. | 
 |   if (writer->IsBatchMode() && result.status == WRITE_STATUS_OK && | 
 |       result.bytes_written == 0) { | 
 |     result = writer->Flush(); | 
 |   } | 
 |  | 
 |   if (IsWriteError(result.status)) { | 
 |     // Write error for any connectivity probe should not affect the connection | 
 |     // as it is sent on a different path. | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Write probing packet failed with error = " | 
 |                     << result.error_code; | 
 |     return false; | 
 |   } | 
 |  | 
 |   // Send in currrent path. Call OnPacketSent regardless of the write result. | 
 |   sent_packet_manager_.OnPacketSent(packet.get(), packet_send_time, | 
 |                                     packet->transmission_type, | 
 |                                     NO_RETRANSMITTABLE_DATA, measure_rtt); | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     if (sent_packet_manager_.unacked_packets().empty()) { | 
 |       QUIC_BUG(quic_bug_10511_32) | 
 |           << "Unacked map is empty right after packet is sent"; | 
 |     } else { | 
 |       debug_visitor_->OnPacketSent( | 
 |           packet->packet_number, packet->encrypted_length, | 
 |           packet->has_crypto_handshake, packet->transmission_type, | 
 |           packet->encryption_level, | 
 |           sent_packet_manager_.unacked_packets() | 
 |               .rbegin() | 
 |               ->retransmittable_frames, | 
 |           packet->nonretransmittable_frames, packet_send_time); | 
 |     } | 
 |   } | 
 |  | 
 |   if (IsWriteBlockedStatus(result.status)) { | 
 |     if (writer == writer_) { | 
 |       // Visitor should not be write blocked if the probing writer is not the | 
 |       // default packet writer. | 
 |       visitor_->OnWriteBlocked(); | 
 |     } | 
 |     if (result.status == WRITE_STATUS_BLOCKED_DATA_BUFFERED) { | 
 |       QUIC_DLOG(INFO) << ENDPOINT << "Write probing packet blocked"; | 
 |     } | 
 |   } | 
 |  | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::DisableMtuDiscovery() { | 
 |   mtu_discoverer_.Disable(); | 
 |   mtu_discovery_alarm_->Cancel(); | 
 | } | 
 |  | 
 | void QuicConnection::DiscoverMtu() { | 
 |   QUICHE_DCHECK(!mtu_discovery_alarm_->IsSet()); | 
 |  | 
 |   const QuicPacketNumber largest_sent_packet = | 
 |       sent_packet_manager_.GetLargestSentPacket(); | 
 |   if (mtu_discoverer_.ShouldProbeMtu(largest_sent_packet)) { | 
 |     ++mtu_probe_count_; | 
 |     SendMtuDiscoveryPacket( | 
 |         mtu_discoverer_.GetUpdatedMtuProbeSize(largest_sent_packet)); | 
 |   } | 
 |   QUICHE_DCHECK(!mtu_discovery_alarm_->IsSet()); | 
 | } | 
 |  | 
 | void QuicConnection::OnEffectivePeerMigrationValidated() { | 
 |   if (active_effective_peer_migration_type_ == NO_CHANGE) { | 
 |     QUIC_BUG(quic_bug_10511_33) << "No migration underway."; | 
 |     return; | 
 |   } | 
 |   highest_packet_sent_before_effective_peer_migration_.Clear(); | 
 |   const bool send_address_token = | 
 |       active_effective_peer_migration_type_ != PORT_CHANGE; | 
 |   active_effective_peer_migration_type_ = NO_CHANGE; | 
 |   ++stats_.num_validated_peer_migration; | 
 |   if (!validate_client_addresses_) { | 
 |     return; | 
 |   } | 
 |   QUIC_CODE_COUNT_N(quic_server_reverse_validate_new_path3, 2, 6); | 
 |   if (debug_visitor_ != nullptr) { | 
 |     const QuicTime now = clock_->ApproximateNow(); | 
 |     if (now >= stats_.handshake_completion_time) { | 
 |       debug_visitor_->OnPeerMigrationValidated( | 
 |           now - stats_.handshake_completion_time); | 
 |     } else { | 
 |       QUIC_BUG(quic_bug_10511_34) | 
 |           << "Handshake completion time is larger than current time."; | 
 |     } | 
 |   } | 
 |  | 
 |   // Lift anti-amplification limit. | 
 |   default_path_.validated = true; | 
 |   alternative_path_.Clear(); | 
 |   if (send_address_token) { | 
 |     visitor_->MaybeSendAddressToken(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::StartEffectivePeerMigration(AddressChangeType type) { | 
 |   // TODO(fayang): Currently, all peer address change type are allowed. Need to | 
 |   // add a method ShouldAllowPeerAddressChange(PeerAddressChangeType type) to | 
 |   // determine whether |type| is allowed. | 
 |   if (!validate_client_addresses_) { | 
 |     if (type == NO_CHANGE) { | 
 |       QUIC_BUG(quic_bug_10511_35) | 
 |           << "EffectivePeerMigration started without address change."; | 
 |       return; | 
 |     } | 
 |     QUIC_DLOG(INFO) | 
 |         << ENDPOINT << "Effective peer's ip:port changed from " | 
 |         << default_path_.peer_address.ToString() << " to " | 
 |         << GetEffectivePeerAddressFromCurrentPacket().ToString() | 
 |         << ", address change type is " << type | 
 |         << ", migrating connection without validating new client address."; | 
 |  | 
 |     highest_packet_sent_before_effective_peer_migration_ = | 
 |         sent_packet_manager_.GetLargestSentPacket(); | 
 |     default_path_.peer_address = GetEffectivePeerAddressFromCurrentPacket(); | 
 |     active_effective_peer_migration_type_ = type; | 
 |  | 
 |     OnConnectionMigration(); | 
 |     return; | 
 |   } | 
 |  | 
 |   QUIC_CODE_COUNT_N(quic_server_reverse_validate_new_path3, 3, 6); | 
 |   if (type == NO_CHANGE) { | 
 |     UpdatePeerAddress(last_received_packet_info_.source_address); | 
 |     QUIC_BUG(quic_bug_10511_36) | 
 |         << "EffectivePeerMigration started without address change."; | 
 |     return; | 
 |   } | 
 |   if (GetQuicReloadableFlag( | 
 |           quic_flush_pending_frames_and_padding_bytes_on_migration)) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT( | 
 |         quic_flush_pending_frames_and_padding_bytes_on_migration); | 
 |     // There could be pending NEW_TOKEN_FRAME triggered by non-probing | 
 |     // PATH_RESPONSE_FRAME in the same packet or pending padding bytes in the | 
 |     // packet creator. | 
 |     packet_creator_.FlushCurrentPacket(); | 
 |     packet_creator_.SendRemainingPendingPadding(); | 
 |     if (!connected_) { | 
 |       return; | 
 |     } | 
 |   } else { | 
 |     if (packet_creator_.HasPendingFrames()) { | 
 |       packet_creator_.FlushCurrentPacket(); | 
 |       if (!connected_) { | 
 |         return; | 
 |       } | 
 |     } | 
 |   } | 
 |  | 
 |   // Action items: | 
 |   //   1. Switch congestion controller; | 
 |   //   2. Update default_path_ (addresses, validation and bytes accounting); | 
 |   //   3. Save previous default path if needed; | 
 |   //   4. Kick off reverse path validation if needed. | 
 |   // Items 1 and 2 are must-to-do. Items 3 and 4 depends on if the new address | 
 |   // is validated or not and which path the incoming packet is on. | 
 |  | 
 |   const QuicSocketAddress current_effective_peer_address = | 
 |       GetEffectivePeerAddressFromCurrentPacket(); | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "Effective peer's ip:port changed from " | 
 |                   << default_path_.peer_address.ToString() << " to " | 
 |                   << current_effective_peer_address.ToString() | 
 |                   << ", address change type is " << type | 
 |                   << ", migrating connection."; | 
 |  | 
 |   const QuicSocketAddress previous_direct_peer_address = direct_peer_address_; | 
 |   PathState previous_default_path = std::move(default_path_); | 
 |   active_effective_peer_migration_type_ = type; | 
 |   MaybeClearQueuedPacketsOnPathChange(); | 
 |   OnConnectionMigration(); | 
 |  | 
 |   // Update congestion controller if the address change type is not PORT_CHANGE. | 
 |   if (type == PORT_CHANGE) { | 
 |     QUICHE_DCHECK(previous_default_path.validated || | 
 |                   (alternative_path_.validated && | 
 |                    alternative_path_.send_algorithm != nullptr)); | 
 |     // No need to store previous congestion controller because either the new | 
 |     // default path is validated or the alternative path is validated and | 
 |     // already has associated congestion controller. | 
 |   } else { | 
 |     previous_default_path.rtt_stats.emplace(); | 
 |     previous_default_path.rtt_stats->CloneFrom( | 
 |         *sent_packet_manager_.GetRttStats()); | 
 |     // If the new peer address share the same IP with the alternative path, the | 
 |     // connection should switch to the congestion controller of the alternative | 
 |     // path. Otherwise, the connection should use a brand new one. | 
 |     // In order to re-use existing code in sent_packet_manager_, reset | 
 |     // congestion controller to initial state first and then change to the one | 
 |     // on alternative path. | 
 |     // TODO(danzh) combine these two steps into one after deprecating gQUIC. | 
 |     previous_default_path.send_algorithm = OnPeerIpAddressChanged(); | 
 |  | 
 |     if (alternative_path_.peer_address.host() == | 
 |             current_effective_peer_address.host() && | 
 |         alternative_path_.send_algorithm != nullptr) { | 
 |       // Update the default path with the congestion controller of the | 
 |       // alternative path. | 
 |       sent_packet_manager_.SetSendAlgorithm( | 
 |           alternative_path_.send_algorithm.release()); | 
 |       sent_packet_manager_.SetRttStats( | 
 |           std::move(alternative_path_.rtt_stats).value()); | 
 |     } | 
 |   } | 
 |   // Update to the new peer address. | 
 |   UpdatePeerAddress(last_received_packet_info_.source_address); | 
 |   // Update the default path. | 
 |   if (IsAlternativePath(last_received_packet_info_.destination_address, | 
 |                         current_effective_peer_address)) { | 
 |     SetDefaultPathState(std::move(alternative_path_)); | 
 |   } else { | 
 |     QuicConnectionId client_connection_id; | 
 |     absl::optional<StatelessResetToken> stateless_reset_token; | 
 |     FindMatchingOrNewClientConnectionIdOrToken( | 
 |         previous_default_path, alternative_path_, | 
 |         last_packet_destination_connection_id_, &client_connection_id, | 
 |         &stateless_reset_token); | 
 |     SetDefaultPathState(PathState( | 
 |         last_received_packet_info_.destination_address, | 
 |         current_effective_peer_address, client_connection_id, | 
 |         last_packet_destination_connection_id_, stateless_reset_token)); | 
 |     // The path is considered validated if its peer IP address matches any | 
 |     // validated path's peer IP address. | 
 |     default_path_.validated = | 
 |         (alternative_path_.peer_address.host() == | 
 |              current_effective_peer_address.host() && | 
 |          alternative_path_.validated) || | 
 |         (previous_default_path.validated && type == PORT_CHANGE); | 
 |   } | 
 |   if (!last_received_packet_info_.received_bytes_counted) { | 
 |     // Increment bytes counting on the new default path. | 
 |     default_path_.bytes_received_before_address_validation += last_size_; | 
 |     last_received_packet_info_.received_bytes_counted = true; | 
 |   } | 
 |  | 
 |   if (!previous_default_path.validated) { | 
 |     // If the old address is under validation, cancel and fail it. Failing to | 
 |     // validate the old path shouldn't take any effect. | 
 |     QUIC_DVLOG(1) << "Cancel validation of previous peer address change to " | 
 |                   << previous_default_path.peer_address | 
 |                   << " upon peer migration to " << default_path_.peer_address; | 
 |     path_validator_.CancelPathValidation(); | 
 |     ++stats_.num_peer_migration_while_validating_default_path; | 
 |   } | 
 |  | 
 |   // Clear alternative path if the new default path shares the same IP as the | 
 |   // alternative path. | 
 |   if (alternative_path_.peer_address.host() == | 
 |       default_path_.peer_address.host()) { | 
 |     alternative_path_.Clear(); | 
 |   } | 
 |  | 
 |   if (default_path_.validated) { | 
 |     QUIC_DVLOG(1) << "Peer migrated to a validated address."; | 
 |     // No need to save previous default path, validate new peer address or | 
 |     // update bytes sent/received. | 
 |     if (!(previous_default_path.validated && type == PORT_CHANGE)) { | 
 |       // The alternative path was validated because of proactive reverse path | 
 |       // validation. | 
 |       ++stats_.num_peer_migration_to_proactively_validated_address; | 
 |     } | 
 |     OnEffectivePeerMigrationValidated(); | 
 |     return; | 
 |   } | 
 |  | 
 |   // The new default address is not validated yet. Anti-amplification limit is | 
 |   // enforced. | 
 |   QUICHE_DCHECK(EnforceAntiAmplificationLimit()); | 
 |   QUIC_DVLOG(1) << "Apply anti-amplification limit to effective peer address " | 
 |                 << default_path_.peer_address << " with " | 
 |                 << default_path_.bytes_sent_before_address_validation | 
 |                 << " bytes sent and " | 
 |                 << default_path_.bytes_received_before_address_validation | 
 |                 << " bytes received."; | 
 |  | 
 |   QUICHE_DCHECK(!alternative_path_.peer_address.IsInitialized() || | 
 |                 alternative_path_.peer_address.host() != | 
 |                     default_path_.peer_address.host()); | 
 |  | 
 |   // Save previous default path to the altenative path. | 
 |   if (previous_default_path.validated) { | 
 |     // The old path is a validated path which the connection might revert back | 
 |     // to later. Store it as the alternative path. | 
 |     alternative_path_ = std::move(previous_default_path); | 
 |     QUICHE_DCHECK(alternative_path_.send_algorithm != nullptr); | 
 |   } | 
 |  | 
 |   // If the new address is not validated and the connection is not already | 
 |   // validating that address, a new reverse path validation is needed. | 
 |   if (!path_validator_.IsValidatingPeerAddress( | 
 |           current_effective_peer_address)) { | 
 |     ++stats_.num_reverse_path_validtion_upon_migration; | 
 |     ValidatePath(std::make_unique<ReversePathValidationContext>( | 
 |                      default_path_.self_address, peer_address(), | 
 |                      default_path_.peer_address, this), | 
 |                  std::make_unique<ReversePathValidationResultDelegate>( | 
 |                      this, previous_direct_peer_address)); | 
 |   } else { | 
 |     QUIC_DVLOG(1) << "Peer address " << default_path_.peer_address | 
 |                   << " is already under validation, wait for result."; | 
 |     ++stats_.num_peer_migration_to_proactively_validated_address; | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnConnectionMigration() { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     const QuicTime now = clock_->ApproximateNow(); | 
 |     if (now >= stats_.handshake_completion_time) { | 
 |       debug_visitor_->OnPeerAddressChange( | 
 |           active_effective_peer_migration_type_, | 
 |           now - stats_.handshake_completion_time); | 
 |     } | 
 |   } | 
 |   visitor_->OnConnectionMigration(active_effective_peer_migration_type_); | 
 |   if (active_effective_peer_migration_type_ != PORT_CHANGE && | 
 |       active_effective_peer_migration_type_ != IPV4_SUBNET_CHANGE && | 
 |       !validate_client_addresses_) { | 
 |     sent_packet_manager_.OnConnectionMigration(/*reset_send_algorithm=*/false); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::IsCurrentPacketConnectivityProbing() const { | 
 |   return is_current_packet_connectivity_probing_; | 
 | } | 
 |  | 
 | bool QuicConnection::ack_frame_updated() const { | 
 |   return uber_received_packet_manager_.IsAckFrameUpdated(); | 
 | } | 
 |  | 
 | absl::string_view QuicConnection::GetCurrentPacket() { | 
 |   if (current_packet_data_ == nullptr) { | 
 |     return absl::string_view(); | 
 |   } | 
 |   return absl::string_view(current_packet_data_, last_size_); | 
 | } | 
 |  | 
 | bool QuicConnection::MaybeConsiderAsMemoryCorruption( | 
 |     const QuicStreamFrame& frame) { | 
 |   if (QuicUtils::IsCryptoStreamId(transport_version(), frame.stream_id) || | 
 |       last_decrypted_packet_level_ != ENCRYPTION_INITIAL) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (perspective_ == Perspective::IS_SERVER && | 
 |       frame.data_length >= sizeof(kCHLO) && | 
 |       strncmp(frame.data_buffer, reinterpret_cast<const char*>(&kCHLO), | 
 |               sizeof(kCHLO)) == 0) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (perspective_ == Perspective::IS_CLIENT && | 
 |       frame.data_length >= sizeof(kREJ) && | 
 |       strncmp(frame.data_buffer, reinterpret_cast<const char*>(&kREJ), | 
 |               sizeof(kREJ)) == 0) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   return false; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeSendProbingRetransmissions() { | 
 |   QUICHE_DCHECK(fill_up_link_during_probing_); | 
 |  | 
 |   // Don't send probing retransmissions until the handshake has completed. | 
 |   if (!IsHandshakeComplete() || | 
 |       sent_packet_manager().HasUnackedCryptoPackets()) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (probing_retransmission_pending_) { | 
 |     QUIC_BUG(quic_bug_10511_37) | 
 |         << "MaybeSendProbingRetransmissions is called while another call " | 
 |            "to it is already in progress"; | 
 |     return; | 
 |   } | 
 |  | 
 |   probing_retransmission_pending_ = true; | 
 |   SendProbingRetransmissions(); | 
 |   probing_retransmission_pending_ = false; | 
 | } | 
 |  | 
 | void QuicConnection::CheckIfApplicationLimited() { | 
 |   if (!connected_ || probing_retransmission_pending_) { | 
 |     return; | 
 |   } | 
 |  | 
 |   bool application_limited = | 
 |       buffered_packets_.empty() && !visitor_->WillingAndAbleToWrite(); | 
 |  | 
 |   if (!application_limited) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (fill_up_link_during_probing_) { | 
 |     MaybeSendProbingRetransmissions(); | 
 |     if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) { | 
 |       return; | 
 |     } | 
 |   } | 
 |  | 
 |   sent_packet_manager_.OnApplicationLimited(); | 
 | } | 
 |  | 
 | bool QuicConnection::UpdatePacketContent(QuicFrameType type) { | 
 |   most_recent_frame_type_ = type; | 
 |   if (version().HasIetfQuicFrames()) { | 
 |     if (!QuicUtils::IsProbingFrame(type)) { | 
 |       MaybeStartIetfPeerMigration(); | 
 |       return connected_; | 
 |     } | 
 |     QuicSocketAddress current_effective_peer_address = | 
 |         GetEffectivePeerAddressFromCurrentPacket(); | 
 |     if (!count_bytes_on_alternative_path_separately_ || | 
 |         IsDefaultPath(last_received_packet_info_.destination_address, | 
 |                       last_received_packet_info_.source_address)) { | 
 |       return connected_; | 
 |     } | 
 |     QUIC_CODE_COUNT_N(quic_count_bytes_on_alternative_path_seperately, 3, 5); | 
 |     if (perspective_ == Perspective::IS_SERVER && | 
 |         type == PATH_CHALLENGE_FRAME && | 
 |         !IsAlternativePath(last_received_packet_info_.destination_address, | 
 |                            current_effective_peer_address)) { | 
 |       QUIC_DVLOG(1) | 
 |           << "The peer is probing a new path with effective peer address " | 
 |           << current_effective_peer_address << ",  self address " | 
 |           << last_received_packet_info_.destination_address; | 
 |       if (!validate_client_addresses_) { | 
 |         QuicConnectionId client_cid; | 
 |         absl::optional<StatelessResetToken> stateless_reset_token; | 
 |         FindMatchingOrNewClientConnectionIdOrToken( | 
 |             default_path_, alternative_path_, | 
 |             last_packet_destination_connection_id_, &client_cid, | 
 |             &stateless_reset_token); | 
 |         alternative_path_ = PathState( | 
 |             last_received_packet_info_.destination_address, | 
 |             current_effective_peer_address, client_cid, | 
 |             last_packet_destination_connection_id_, stateless_reset_token); | 
 |       } else if (!default_path_.validated) { | 
 |         QUIC_CODE_COUNT_N(quic_server_reverse_validate_new_path3, 4, 6); | 
 |         // Skip reverse path validation because either handshake hasn't | 
 |         // completed or the connection is validating the default path. Using | 
 |         // PATH_CHALLENGE to validate alternative client address before | 
 |         // handshake gets comfirmed is meaningless because anyone can respond to | 
 |         // it. If the connection is validating the default path, this | 
 |         // alternative path is currently the only validated path which shouldn't | 
 |         // be overridden. | 
 |         QUIC_DVLOG(1) << "The connection hasn't finished handshake or is " | 
 |                          "validating a recent peer address change."; | 
 |         QUIC_BUG_IF(quic_bug_12714_30, | 
 |                     IsHandshakeConfirmed() && !alternative_path_.validated) | 
 |             << "No validated peer address to send after handshake comfirmed."; | 
 |       } else if (!IsReceivedPeerAddressValidated()) { | 
 |         QUIC_CODE_COUNT_N(quic_server_reverse_validate_new_path3, 5, 6); | 
 |         QuicConnectionId client_connection_id; | 
 |         absl::optional<StatelessResetToken> stateless_reset_token; | 
 |         FindMatchingOrNewClientConnectionIdOrToken( | 
 |             default_path_, alternative_path_, | 
 |             last_packet_destination_connection_id_, &client_connection_id, | 
 |             &stateless_reset_token); | 
 |         // Only override alternative path state upon receiving a PATH_CHALLENGE | 
 |         // from an unvalidated peer address, and the connection isn't validating | 
 |         // a recent peer migration. | 
 |         alternative_path_ = PathState( | 
 |             last_received_packet_info_.destination_address, | 
 |             current_effective_peer_address, client_connection_id, | 
 |             last_packet_destination_connection_id_, stateless_reset_token); | 
 |         should_proactively_validate_peer_address_on_path_challenge_ = true; | 
 |       } | 
 |     } | 
 |     MaybeUpdateBytesReceivedFromAlternativeAddress(last_size_); | 
 |     return connected_; | 
 |   } | 
 |   // Packet content is tracked to identify connectivity probe in non-IETF | 
 |   // version, where a connectivity probe is defined as | 
 |   // - a padded PING packet with peer address change received by server, | 
 |   // - a padded PING packet on new path received by client. | 
 |  | 
 |   if (current_packet_content_ == NOT_PADDED_PING) { | 
 |     // We have already learned the current packet is not a connectivity | 
 |     // probing packet. Peer migration should have already been started earlier | 
 |     // if needed. | 
 |     return connected_; | 
 |   } | 
 |  | 
 |   if (type == PING_FRAME) { | 
 |     if (current_packet_content_ == NO_FRAMES_RECEIVED) { | 
 |       current_packet_content_ = FIRST_FRAME_IS_PING; | 
 |       return connected_; | 
 |     } | 
 |   } | 
 |  | 
 |   // In Google QUIC, we look for a packet with just a PING and PADDING. | 
 |   // If the condition is met, mark things as connectivity-probing, causing | 
 |   // later processing to generate the correct response. | 
 |   if (type == PADDING_FRAME && current_packet_content_ == FIRST_FRAME_IS_PING) { | 
 |     current_packet_content_ = SECOND_FRAME_IS_PADDING; | 
 |     if (perspective_ == Perspective::IS_SERVER) { | 
 |       is_current_packet_connectivity_probing_ = | 
 |           current_effective_peer_migration_type_ != NO_CHANGE; | 
 |       QUIC_DLOG_IF(INFO, is_current_packet_connectivity_probing_) | 
 |           << ENDPOINT | 
 |           << "Detected connectivity probing packet. " | 
 |              "current_effective_peer_migration_type_:" | 
 |           << current_effective_peer_migration_type_; | 
 |     } else { | 
 |       is_current_packet_connectivity_probing_ = | 
 |           (last_received_packet_info_.source_address != peer_address()) || | 
 |           (last_received_packet_info_.destination_address != | 
 |            default_path_.self_address); | 
 |       QUIC_DLOG_IF(INFO, is_current_packet_connectivity_probing_) | 
 |           << ENDPOINT | 
 |           << "Detected connectivity probing packet. " | 
 |              "last_packet_source_address:" | 
 |           << last_received_packet_info_.source_address | 
 |           << ", peer_address_:" << peer_address() | 
 |           << ", last_packet_destination_address:" | 
 |           << last_received_packet_info_.destination_address | 
 |           << ", default path self_address :" << default_path_.self_address; | 
 |     } | 
 |     return connected_; | 
 |   } | 
 |  | 
 |   current_packet_content_ = NOT_PADDED_PING; | 
 |   if (GetLargestReceivedPacket().IsInitialized() && | 
 |       last_header_.packet_number == GetLargestReceivedPacket()) { | 
 |     UpdatePeerAddress(last_received_packet_info_.source_address); | 
 |     if (current_effective_peer_migration_type_ != NO_CHANGE) { | 
 |       // Start effective peer migration immediately when the current packet is | 
 |       // confirmed not a connectivity probing packet. | 
 |       StartEffectivePeerMigration(current_effective_peer_migration_type_); | 
 |     } | 
 |   } | 
 |   current_effective_peer_migration_type_ = NO_CHANGE; | 
 |   return connected_; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeStartIetfPeerMigration() { | 
 |   QUICHE_DCHECK(version().HasIetfQuicFrames()); | 
 |   if (current_effective_peer_migration_type_ != NO_CHANGE && | 
 |       !IsHandshakeConfirmed()) { | 
 |     QUIC_LOG_EVERY_N_SEC(INFO, 60) | 
 |         << ENDPOINT << "Effective peer's ip:port changed from " | 
 |         << default_path_.peer_address.ToString() << " to " | 
 |         << GetEffectivePeerAddressFromCurrentPacket().ToString() | 
 |         << " before handshake confirmed, " | 
 |            "current_effective_peer_migration_type_: " | 
 |         << current_effective_peer_migration_type_; | 
 |     // Peer migrated before handshake gets confirmed. | 
 |     CloseConnection((current_effective_peer_migration_type_ == PORT_CHANGE | 
 |                          ? QUIC_PEER_PORT_CHANGE_HANDSHAKE_UNCONFIRMED | 
 |                          : QUIC_CONNECTION_MIGRATION_HANDSHAKE_UNCONFIRMED), | 
 |                     "Peer address changed before handshake is confirmed.", | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return; | 
 |   } | 
 |  | 
 |   if (GetLargestReceivedPacket().IsInitialized() && | 
 |       last_header_.packet_number == GetLargestReceivedPacket()) { | 
 |     if (current_effective_peer_migration_type_ != NO_CHANGE) { | 
 |       // Start effective peer migration when the current packet contains a | 
 |       // non-probing frame. | 
 |       // TODO(fayang): When multiple packet number spaces is supported, only | 
 |       // start peer migration for the application data. | 
 |       if (!validate_client_addresses_) { | 
 |         UpdatePeerAddress(last_received_packet_info_.source_address); | 
 |       } | 
 |       StartEffectivePeerMigration(current_effective_peer_migration_type_); | 
 |     } else { | 
 |       UpdatePeerAddress(last_received_packet_info_.source_address); | 
 |     } | 
 |   } | 
 |   current_effective_peer_migration_type_ = NO_CHANGE; | 
 | } | 
 |  | 
 | void QuicConnection::PostProcessAfterAckFrame(bool send_stop_waiting, | 
 |                                               bool acked_new_packet) { | 
 |   if (no_stop_waiting_frames_ && !packet_creator_.has_ack()) { | 
 |     uber_received_packet_manager_.DontWaitForPacketsBefore( | 
 |         last_decrypted_packet_level_, | 
 |         SupportsMultiplePacketNumberSpaces() | 
 |             ? sent_packet_manager_.GetLargestPacketPeerKnowsIsAcked( | 
 |                   last_decrypted_packet_level_) | 
 |             : sent_packet_manager_.largest_packet_peer_knows_is_acked()); | 
 |   } | 
 |   // Always reset the retransmission alarm when an ack comes in, since we now | 
 |   // have a better estimate of the current rtt than when it was set. | 
 |   SetRetransmissionAlarm(); | 
 |   if (acked_new_packet) { | 
 |     OnForwardProgressMade(); | 
 |   } else if (default_enable_5rto_blackhole_detection_ && | 
 |              !sent_packet_manager_.HasInFlightPackets() && | 
 |              blackhole_detector_.IsDetectionInProgress()) { | 
 |     // In case no new packets get acknowledged, it is possible packets are | 
 |     // detected lost because of time based loss detection. Cancel blackhole | 
 |     // detection if there is no packets in flight. | 
 |     blackhole_detector_.StopDetection(/*permanent=*/false); | 
 |   } | 
 |  | 
 |   if (send_stop_waiting) { | 
 |     ++stop_waiting_count_; | 
 |   } else { | 
 |     stop_waiting_count_ = 0; | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::SetSessionNotifier( | 
 |     SessionNotifierInterface* session_notifier) { | 
 |   sent_packet_manager_.SetSessionNotifier(session_notifier); | 
 | } | 
 |  | 
 | void QuicConnection::SetDataProducer( | 
 |     QuicStreamFrameDataProducer* data_producer) { | 
 |   framer_.set_data_producer(data_producer); | 
 | } | 
 |  | 
 | void QuicConnection::SetTransmissionType(TransmissionType type) { | 
 |   packet_creator_.SetTransmissionType(type); | 
 | } | 
 |  | 
 | void QuicConnection::UpdateReleaseTimeIntoFuture() { | 
 |   QUICHE_DCHECK(supports_release_time_); | 
 |  | 
 |   const QuicTime::Delta prior_max_release_time = release_time_into_future_; | 
 |   release_time_into_future_ = std::max( | 
 |       QuicTime::Delta::FromMilliseconds(kMinReleaseTimeIntoFutureMs), | 
 |       std::min( | 
 |           QuicTime::Delta::FromMilliseconds( | 
 |               GetQuicFlag(FLAGS_quic_max_pace_time_into_future_ms)), | 
 |           sent_packet_manager_.GetRttStats()->SmoothedOrInitialRtt() * | 
 |               GetQuicFlag(FLAGS_quic_pace_time_into_future_srtt_fraction))); | 
 |   QUIC_DVLOG(3) << "Updated max release time delay from " | 
 |                 << prior_max_release_time << " to " | 
 |                 << release_time_into_future_; | 
 | } | 
 |  | 
 | void QuicConnection::ResetAckStates() { | 
 |   ack_alarm_->Cancel(); | 
 |   stop_waiting_count_ = 0; | 
 |   uber_received_packet_manager_.ResetAckStates(encryption_level_); | 
 | } | 
 |  | 
 | MessageStatus QuicConnection::SendMessage(QuicMessageId message_id, | 
 |                                           absl::Span<QuicMemSlice> message, | 
 |                                           bool flush) { | 
 |   if (!VersionSupportsMessageFrames(transport_version())) { | 
 |     QUIC_BUG(quic_bug_10511_38) | 
 |         << "MESSAGE frame is not supported for version " << transport_version(); | 
 |     return MESSAGE_STATUS_UNSUPPORTED; | 
 |   } | 
 |   if (MemSliceSpanTotalSize(message) > GetCurrentLargestMessagePayload()) { | 
 |     return MESSAGE_STATUS_TOO_LARGE; | 
 |   } | 
 |   if (!connected_ || (!flush && !CanWrite(HAS_RETRANSMITTABLE_DATA))) { | 
 |     return MESSAGE_STATUS_BLOCKED; | 
 |   } | 
 |   ScopedPacketFlusher flusher(this); | 
 |   return packet_creator_.AddMessageFrame(message_id, message); | 
 | } | 
 |  | 
 | QuicPacketLength QuicConnection::GetCurrentLargestMessagePayload() const { | 
 |   return packet_creator_.GetCurrentLargestMessagePayload(); | 
 | } | 
 |  | 
 | QuicPacketLength QuicConnection::GetGuaranteedLargestMessagePayload() const { | 
 |   return packet_creator_.GetGuaranteedLargestMessagePayload(); | 
 | } | 
 |  | 
 | uint32_t QuicConnection::cipher_id() const { | 
 |   if (version().KnowsWhichDecrypterToUse()) { | 
 |     return framer_.GetDecrypter(last_decrypted_packet_level_)->cipher_id(); | 
 |   } | 
 |   return framer_.decrypter()->cipher_id(); | 
 | } | 
 |  | 
 | EncryptionLevel QuicConnection::GetConnectionCloseEncryptionLevel() const { | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     return encryption_level_; | 
 |   } | 
 |   if (IsHandshakeComplete()) { | 
 |     // A forward secure packet has been received. | 
 |     QUIC_BUG_IF(quic_bug_12714_31, | 
 |                 encryption_level_ != ENCRYPTION_FORWARD_SECURE) | 
 |         << ENDPOINT << "Unexpected connection close encryption level " | 
 |         << encryption_level_; | 
 |     return ENCRYPTION_FORWARD_SECURE; | 
 |   } | 
 |   if (framer_.HasEncrypterOfEncryptionLevel(ENCRYPTION_ZERO_RTT)) { | 
 |     if (encryption_level_ != ENCRYPTION_ZERO_RTT) { | 
 |       if (version().HasIetfInvariantHeader()) { | 
 |         QUIC_CODE_COUNT(quic_wrong_encryption_level_connection_close_ietf); | 
 |       } else { | 
 |         QUIC_CODE_COUNT(quic_wrong_encryption_level_connection_close); | 
 |       } | 
 |     } | 
 |     return ENCRYPTION_ZERO_RTT; | 
 |   } | 
 |   return ENCRYPTION_INITIAL; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeBundleCryptoDataWithAcks() { | 
 |   QUICHE_DCHECK(SupportsMultiplePacketNumberSpaces()); | 
 |   if (IsHandshakeConfirmed()) { | 
 |     return; | 
 |   } | 
 |   PacketNumberSpace space = HANDSHAKE_DATA; | 
 |   if (perspective() == Perspective::IS_SERVER && | 
 |       framer_.HasEncrypterOfEncryptionLevel(ENCRYPTION_INITIAL)) { | 
 |     // On the server side, sends INITIAL data with INITIAL ACK if initial key is | 
 |     // available. | 
 |     space = INITIAL_DATA; | 
 |   } | 
 |   const QuicTime ack_timeout = | 
 |       uber_received_packet_manager_.GetAckTimeout(space); | 
 |   if (!ack_timeout.IsInitialized() || | 
 |       (ack_timeout > clock_->ApproximateNow() && | 
 |        ack_timeout > uber_received_packet_manager_.GetEarliestAckTimeout())) { | 
 |     // No pending ACK of space. | 
 |     return; | 
 |   } | 
 |   if (coalesced_packet_.length() > 0) { | 
 |     // Do not bundle CRYPTO data if the ACK could be coalesced with other | 
 |     // packets. | 
 |     return; | 
 |   } | 
 |  | 
 |   if (!framer_.HasAnEncrypterForSpace(space)) { | 
 |     QUIC_BUG(quic_bug_10511_39) | 
 |         << ENDPOINT | 
 |         << "Try to bundle crypto with ACK with missing key of space " | 
 |         << PacketNumberSpaceToString(space); | 
 |     return; | 
 |   } | 
 |  | 
 |   sent_packet_manager_.RetransmitDataOfSpaceIfAny(space); | 
 | } | 
 |  | 
 | void QuicConnection::SendAllPendingAcks() { | 
 |   QUICHE_DCHECK(SupportsMultiplePacketNumberSpaces()); | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Trying to send all pending ACKs"; | 
 |   ack_alarm_->Cancel(); | 
 |   QuicTime earliest_ack_timeout = | 
 |       uber_received_packet_manager_.GetEarliestAckTimeout(); | 
 |   QUIC_BUG_IF(quic_bug_12714_32, !earliest_ack_timeout.IsInitialized()); | 
 |   MaybeBundleCryptoDataWithAcks(); | 
 |   earliest_ack_timeout = uber_received_packet_manager_.GetEarliestAckTimeout(); | 
 |   if (!earliest_ack_timeout.IsInitialized()) { | 
 |     return; | 
 |   } | 
 |   for (int8_t i = INITIAL_DATA; i <= APPLICATION_DATA; ++i) { | 
 |     const QuicTime ack_timeout = uber_received_packet_manager_.GetAckTimeout( | 
 |         static_cast<PacketNumberSpace>(i)); | 
 |     if (!ack_timeout.IsInitialized()) { | 
 |       continue; | 
 |     } | 
 |     if (!framer_.HasAnEncrypterForSpace(static_cast<PacketNumberSpace>(i))) { | 
 |       // The key has been dropped. | 
 |       continue; | 
 |     } | 
 |     if (ack_timeout > clock_->ApproximateNow() && | 
 |         ack_timeout > earliest_ack_timeout) { | 
 |       // Always send the earliest ACK to make forward progress in case alarm | 
 |       // fires early. | 
 |       continue; | 
 |     } | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Sending ACK of packet number space " | 
 |                   << PacketNumberSpaceToString( | 
 |                          static_cast<PacketNumberSpace>(i)); | 
 |     ScopedEncryptionLevelContext context( | 
 |         this, QuicUtils::GetEncryptionLevel(static_cast<PacketNumberSpace>(i))); | 
 |     QuicFrames frames; | 
 |     frames.push_back(uber_received_packet_manager_.GetUpdatedAckFrame( | 
 |         static_cast<PacketNumberSpace>(i), clock_->ApproximateNow())); | 
 |     const bool flushed = packet_creator_.FlushAckFrame(frames); | 
 |     if (!flushed) { | 
 |       // Connection is write blocked. | 
 |       QUIC_BUG_IF(quic_bug_12714_33, | 
 |                   !writer_->IsWriteBlocked() && !LimitedByAmplificationFactor()) | 
 |           << "Writer not blocked and not throttled by amplification factor, " | 
 |              "but ACK not flushed for packet space:" | 
 |           << i; | 
 |       break; | 
 |     } | 
 |     ResetAckStates(); | 
 |   } | 
 |  | 
 |   const QuicTime timeout = | 
 |       uber_received_packet_manager_.GetEarliestAckTimeout(); | 
 |   if (timeout.IsInitialized()) { | 
 |     // If there are ACKs pending, re-arm ack alarm. | 
 |     ack_alarm_->Update(timeout, kAlarmGranularity); | 
 |   } | 
 |   // Only try to bundle retransmittable data with ACK frame if default | 
 |   // encryption level is forward secure. | 
 |   if (encryption_level_ != ENCRYPTION_FORWARD_SECURE || | 
 |       !ShouldBundleRetransmittableFrameWithAck()) { | 
 |     return; | 
 |   } | 
 |   consecutive_num_packets_with_no_retransmittable_frames_ = 0; | 
 |   if (packet_creator_.HasPendingRetransmittableFrames() || | 
 |       visitor_->WillingAndAbleToWrite()) { | 
 |     // There are pending retransmittable frames. | 
 |     return; | 
 |   } | 
 |  | 
 |   visitor_->OnAckNeedsRetransmittableFrame(); | 
 | } | 
 |  | 
 | bool QuicConnection::ShouldBundleRetransmittableFrameWithAck() const { | 
 |   if (consecutive_num_packets_with_no_retransmittable_frames_ >= | 
 |       max_consecutive_num_packets_with_no_retransmittable_frames_) { | 
 |     return true; | 
 |   } | 
 |   if (bundle_retransmittable_with_pto_ack_ && | 
 |       (sent_packet_manager_.GetConsecutiveRtoCount() > 0 || | 
 |        sent_packet_manager_.GetConsecutivePtoCount() > 0)) { | 
 |     // Bundle a retransmittable frame with an ACK if the PTO or RTO has fired | 
 |     // in order to recover more quickly in cases of temporary network outage. | 
 |     return true; | 
 |   } | 
 |   return false; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeCoalescePacketOfHigherSpace() { | 
 |   if (!connected() || !packet_creator_.HasSoftMaxPacketLength() || | 
 |       fill_coalesced_packet_) { | 
 |     // Make sure MaybeCoalescePacketOfHigherSpace is not re-entrant. | 
 |     return; | 
 |   } | 
 |   // INITIAL or HANDSHAKE retransmission could cause peer to derive new | 
 |   // keys, such that the buffered undecryptable packets may be processed. | 
 |   // This endpoint would derive an inflated RTT sample (which includes the PTO | 
 |   // timeout) when receiving ACKs of those undecryptable packets. To mitigate | 
 |   // this, tries to coalesce a packet of higher encryption level. | 
 |   for (EncryptionLevel retransmission_level : | 
 |        {ENCRYPTION_INITIAL, ENCRYPTION_HANDSHAKE}) { | 
 |     // Coalesce HANDSHAKE with INITIAL retransmission, and coalesce 1-RTT with | 
 |     // HANDSHAKE retransmission. | 
 |     const EncryptionLevel coalesced_level = | 
 |         retransmission_level == ENCRYPTION_INITIAL ? ENCRYPTION_HANDSHAKE | 
 |                                                    : ENCRYPTION_FORWARD_SECURE; | 
 |     if (coalesced_packet_.ContainsPacketOfEncryptionLevel( | 
 |             retransmission_level) && | 
 |         coalesced_packet_.TransmissionTypeOfPacket(retransmission_level) != | 
 |             NOT_RETRANSMISSION && | 
 |         framer_.HasEncrypterOfEncryptionLevel(coalesced_level) && | 
 |         !coalesced_packet_.ContainsPacketOfEncryptionLevel(coalesced_level)) { | 
 |       fill_coalesced_packet_ = true; | 
 |       sent_packet_manager_.RetransmitDataOfSpaceIfAny( | 
 |           QuicUtils::GetPacketNumberSpace(coalesced_level)); | 
 |       fill_coalesced_packet_ = false; | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::FlushCoalescedPacket() { | 
 |   ScopedCoalescedPacketClearer clearer(&coalesced_packet_); | 
 |   if (!connected_) { | 
 |     return false; | 
 |   } | 
 |   if (!version().CanSendCoalescedPackets()) { | 
 |     QUIC_BUG_IF(quic_bug_12714_34, coalesced_packet_.length() > 0); | 
 |     return true; | 
 |   } | 
 |   if (coalesced_packet_.ContainsPacketOfEncryptionLevel(ENCRYPTION_INITIAL) && | 
 |       !framer_.HasEncrypterOfEncryptionLevel(ENCRYPTION_INITIAL)) { | 
 |     // Initial packet will be re-serialized. Neuter it in case initial key has | 
 |     // been dropped. | 
 |     QUIC_BUG(quic_bug_10511_40) | 
 |         << ENDPOINT | 
 |         << "Coalescer contains initial packet while initial key has " | 
 |            "been dropped."; | 
 |     coalesced_packet_.NeuterInitialPacket(); | 
 |   } | 
 |   if (coalesced_packet_.length() == 0) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   char buffer[kMaxOutgoingPacketSize]; | 
 |   const size_t length = packet_creator_.SerializeCoalescedPacket( | 
 |       coalesced_packet_, buffer, coalesced_packet_.max_packet_length()); | 
 |   if (length == 0) { | 
 |     return false; | 
 |   } | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnCoalescedPacketSent(coalesced_packet_, length); | 
 |   } | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Sending coalesced packet " | 
 |                 << coalesced_packet_.ToString(length); | 
 |  | 
 |   if (!buffered_packets_.empty() || HandleWriteBlocked()) { | 
 |     QUIC_DVLOG(1) << ENDPOINT | 
 |                   << "Buffering coalesced packet of len: " << length; | 
 |     buffered_packets_.emplace_back( | 
 |         buffer, static_cast<QuicPacketLength>(length), | 
 |         coalesced_packet_.self_address(), coalesced_packet_.peer_address()); | 
 |     return true; | 
 |   } | 
 |  | 
 |   WriteResult result = writer_->WritePacket( | 
 |       buffer, length, coalesced_packet_.self_address().host(), | 
 |       coalesced_packet_.peer_address(), per_packet_options_); | 
 |   if (IsWriteError(result.status)) { | 
 |     OnWriteError(result.error_code); | 
 |     return false; | 
 |   } | 
 |   if (IsWriteBlockedStatus(result.status)) { | 
 |     visitor_->OnWriteBlocked(); | 
 |     if (result.status != WRITE_STATUS_BLOCKED_DATA_BUFFERED) { | 
 |       QUIC_DVLOG(1) << ENDPOINT | 
 |                     << "Buffering coalesced packet of len: " << length; | 
 |       buffered_packets_.emplace_back( | 
 |           buffer, static_cast<QuicPacketLength>(length), | 
 |           coalesced_packet_.self_address(), coalesced_packet_.peer_address()); | 
 |     } | 
 |   } | 
 |   // Account for added padding. | 
 |   if (length > coalesced_packet_.length()) { | 
 |     size_t padding_size = length - coalesced_packet_.length(); | 
 |     if (!count_bytes_on_alternative_path_separately_) { | 
 |       if (EnforceAntiAmplificationLimit()) { | 
 |         default_path_.bytes_sent_before_address_validation += padding_size; | 
 |       } | 
 |     } else { | 
 |       QUIC_CODE_COUNT_N(quic_count_bytes_on_alternative_path_seperately, 5, 5); | 
 |       if (IsDefaultPath(coalesced_packet_.self_address(), | 
 |                         coalesced_packet_.peer_address())) { | 
 |         if (EnforceAntiAmplificationLimit()) { | 
 |           // Include bytes sent even if they are not in flight. | 
 |           default_path_.bytes_sent_before_address_validation += padding_size; | 
 |         } | 
 |       } else { | 
 |         MaybeUpdateBytesSentToAlternativeAddress( | 
 |             coalesced_packet_.peer_address(), padding_size); | 
 |       } | 
 |     } | 
 |     stats_.bytes_sent += padding_size; | 
 |     if (coalesced_packet_.initial_packet() != nullptr && | 
 |         coalesced_packet_.initial_packet()->transmission_type != | 
 |             NOT_RETRANSMISSION) { | 
 |       stats_.bytes_retransmitted += padding_size; | 
 |     } | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeEnableMultiplePacketNumberSpacesSupport() { | 
 |   if (version().handshake_protocol != PROTOCOL_TLS1_3) { | 
 |     return; | 
 |   } | 
 |   QUIC_DVLOG(1) << ENDPOINT << "connection " << connection_id() | 
 |                 << " supports multiple packet number spaces"; | 
 |   framer_.EnableMultiplePacketNumberSpacesSupport(); | 
 |   sent_packet_manager_.EnableMultiplePacketNumberSpacesSupport(); | 
 |   uber_received_packet_manager_.EnableMultiplePacketNumberSpacesSupport( | 
 |       perspective_); | 
 | } | 
 |  | 
 | bool QuicConnection::SupportsMultiplePacketNumberSpaces() const { | 
 |   return sent_packet_manager_.supports_multiple_packet_number_spaces(); | 
 | } | 
 |  | 
 | void QuicConnection::SetLargestReceivedPacketWithAck( | 
 |     QuicPacketNumber new_value) { | 
 |   if (SupportsMultiplePacketNumberSpaces()) { | 
 |     largest_seen_packets_with_ack_[QuicUtils::GetPacketNumberSpace( | 
 |         last_decrypted_packet_level_)] = new_value; | 
 |   } else { | 
 |     largest_seen_packet_with_ack_ = new_value; | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnForwardProgressMade() { | 
 |   if (!connected_) { | 
 |     return; | 
 |   } | 
 |   if (is_path_degrading_) { | 
 |     visitor_->OnForwardProgressMadeAfterPathDegrading(); | 
 |     is_path_degrading_ = false; | 
 |   } | 
 |   if (sent_packet_manager_.HasInFlightPackets()) { | 
 |     // Restart detections if forward progress has been made. | 
 |     blackhole_detector_.RestartDetection(GetPathDegradingDeadline(), | 
 |                                          GetNetworkBlackholeDeadline(), | 
 |                                          GetPathMtuReductionDeadline()); | 
 |   } else { | 
 |     // Stop detections in quiecense. | 
 |     blackhole_detector_.StopDetection(/*permanent=*/false); | 
 |   } | 
 |   QUIC_BUG_IF(quic_bug_12714_35, | 
 |               perspective_ == Perspective::IS_SERVER && | 
 |                   default_enable_5rto_blackhole_detection_ && | 
 |                   blackhole_detector_.IsDetectionInProgress() && | 
 |                   !sent_packet_manager_.HasInFlightPackets()) | 
 |       << ENDPOINT | 
 |       << "Trying to start blackhole detection without no bytes in flight"; | 
 | } | 
 |  | 
 | QuicPacketNumber QuicConnection::GetLargestReceivedPacketWithAck() const { | 
 |   if (SupportsMultiplePacketNumberSpaces()) { | 
 |     return largest_seen_packets_with_ack_[QuicUtils::GetPacketNumberSpace( | 
 |         last_decrypted_packet_level_)]; | 
 |   } | 
 |   return largest_seen_packet_with_ack_; | 
 | } | 
 |  | 
 | QuicPacketNumber QuicConnection::GetLargestAckedPacket() const { | 
 |   if (SupportsMultiplePacketNumberSpaces()) { | 
 |     return sent_packet_manager_.GetLargestAckedPacket( | 
 |         last_decrypted_packet_level_); | 
 |   } | 
 |   return sent_packet_manager_.GetLargestObserved(); | 
 | } | 
 |  | 
 | QuicPacketNumber QuicConnection::GetLargestReceivedPacket() const { | 
 |   return uber_received_packet_manager_.GetLargestObserved( | 
 |       last_decrypted_packet_level_); | 
 | } | 
 |  | 
 | bool QuicConnection::EnforceAntiAmplificationLimit() const { | 
 |   return version().SupportsAntiAmplificationLimit() && | 
 |          perspective_ == Perspective::IS_SERVER && !default_path_.validated; | 
 | } | 
 |  | 
 | // TODO(danzh) Pass in path object or its reference of some sort to use this | 
 | // method to check anti-amplification limit on non-default path. | 
 | bool QuicConnection::LimitedByAmplificationFactor() const { | 
 |   return EnforceAntiAmplificationLimit() && | 
 |          default_path_.bytes_sent_before_address_validation >= | 
 |              anti_amplification_factor_ * | 
 |                  default_path_.bytes_received_before_address_validation; | 
 | } | 
 |  | 
 | SerializedPacketFate QuicConnection::GetSerializedPacketFate( | 
 |     bool is_mtu_discovery, | 
 |     EncryptionLevel encryption_level) { | 
 |   if (ShouldDiscardPacket(encryption_level)) { | 
 |     return DISCARD; | 
 |   } | 
 |   if (legacy_version_encapsulation_in_progress_) { | 
 |     QUICHE_DCHECK(!is_mtu_discovery); | 
 |     return LEGACY_VERSION_ENCAPSULATE; | 
 |   } | 
 |   if (version().CanSendCoalescedPackets() && !coalescing_done_ && | 
 |       !is_mtu_discovery) { | 
 |     if (!IsHandshakeConfirmed()) { | 
 |       // Before receiving ACK for any 1-RTT packets, always try to coalesce | 
 |       // packet (except MTU discovery packet). | 
 |       return COALESCE; | 
 |     } | 
 |     if (coalesced_packet_.length() > 0) { | 
 |       // If the coalescer is not empty, let this packet go through coalescer | 
 |       // to avoid potential out of order sending. | 
 |       return COALESCE; | 
 |     } | 
 |   } | 
 |   if (!buffered_packets_.empty() || HandleWriteBlocked()) { | 
 |     return BUFFER; | 
 |   } | 
 |   return SEND_TO_WRITER; | 
 | } | 
 |  | 
 | bool QuicConnection::IsHandshakeComplete() const { | 
 |   return visitor_->GetHandshakeState() >= HANDSHAKE_COMPLETE; | 
 | } | 
 |  | 
 | bool QuicConnection::IsHandshakeConfirmed() const { | 
 |   QUICHE_DCHECK_EQ(PROTOCOL_TLS1_3, version().handshake_protocol); | 
 |   return visitor_->GetHandshakeState() == HANDSHAKE_CONFIRMED; | 
 | } | 
 |  | 
 | size_t QuicConnection::min_received_before_ack_decimation() const { | 
 |   return uber_received_packet_manager_.min_received_before_ack_decimation(); | 
 | } | 
 |  | 
 | void QuicConnection::set_min_received_before_ack_decimation(size_t new_value) { | 
 |   uber_received_packet_manager_.set_min_received_before_ack_decimation( | 
 |       new_value); | 
 | } | 
 |  | 
 | const QuicAckFrame& QuicConnection::ack_frame() const { | 
 |   if (SupportsMultiplePacketNumberSpaces()) { | 
 |     return uber_received_packet_manager_.GetAckFrame( | 
 |         QuicUtils::GetPacketNumberSpace(last_decrypted_packet_level_)); | 
 |   } | 
 |   return uber_received_packet_manager_.ack_frame(); | 
 | } | 
 |  | 
 | void QuicConnection::set_client_connection_id( | 
 |     QuicConnectionId client_connection_id) { | 
 |   if (!version().SupportsClientConnectionIds()) { | 
 |     QUIC_BUG_IF(quic_bug_12714_36, !client_connection_id.IsEmpty()) | 
 |         << ENDPOINT << "Attempted to use client connection ID " | 
 |         << client_connection_id << " with unsupported version " << version(); | 
 |     return; | 
 |   } | 
 |   default_path_.client_connection_id = client_connection_id; | 
 |  | 
 |   client_connection_id_is_set_ = true; | 
 |   if (version().HasIetfQuicFrames() && !client_connection_id.IsEmpty()) { | 
 |     if (perspective_ == Perspective::IS_SERVER) { | 
 |       QUICHE_DCHECK(peer_issued_cid_manager_ == nullptr); | 
 |       peer_issued_cid_manager_ = | 
 |           std::make_unique<QuicPeerIssuedConnectionIdManager>( | 
 |               kMinNumOfActiveConnectionIds, client_connection_id, clock_, | 
 |               alarm_factory_, this, context()); | 
 |     } else { | 
 |       // Note in Chromium client, set_client_connection_id is not called and | 
 |       // thus self_issued_cid_manager_ should be null. | 
 |       self_issued_cid_manager_ = MakeSelfIssuedConnectionIdManager(); | 
 |     } | 
 |   } | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "setting client connection ID to " | 
 |                   << default_path_.client_connection_id | 
 |                   << " for connection with server connection ID " | 
 |                   << default_path_.server_connection_id; | 
 |   packet_creator_.SetClientConnectionId(default_path_.client_connection_id); | 
 |   framer_.SetExpectedClientConnectionIdLength( | 
 |       default_path_.client_connection_id.length()); | 
 | } | 
 |  | 
 | void QuicConnection::OnPathDegradingDetected() { | 
 |   is_path_degrading_ = true; | 
 |   visitor_->OnPathDegrading(); | 
 | } | 
 |  | 
 | void QuicConnection::OnBlackholeDetected() { | 
 |   if (default_enable_5rto_blackhole_detection_ && | 
 |       !sent_packet_manager_.HasInFlightPackets()) { | 
 |     QUIC_BUG(quic_bug_10511_41) | 
 |         << ENDPOINT | 
 |         << "Blackhole detected, but there is no bytes in flight, version: " | 
 |         << version(); | 
 |     // Do not close connection if there is no bytes in flight. | 
 |     return; | 
 |   } | 
 |   CloseConnection(QUIC_TOO_MANY_RTOS, "Network blackhole detected", | 
 |                   ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 | } | 
 |  | 
 | void QuicConnection::OnPathMtuReductionDetected() { | 
 |   MaybeRevertToPreviousMtu(); | 
 | } | 
 |  | 
 | void QuicConnection::OnHandshakeTimeout() { | 
 |   const QuicTime::Delta duration = | 
 |       clock_->ApproximateNow() - stats_.connection_creation_time; | 
 |   std::string error_details = absl::StrCat( | 
 |       "Handshake timeout expired after ", duration.ToDebuggingValue(), | 
 |       ". Timeout:", | 
 |       idle_network_detector_.handshake_timeout().ToDebuggingValue()); | 
 |   if (perspective() == Perspective::IS_CLIENT && version().UsesTls()) { | 
 |     absl::StrAppend(&error_details, UndecryptablePacketsInfo()); | 
 |   } | 
 |   QUIC_DVLOG(1) << ENDPOINT << error_details; | 
 |   CloseConnection(QUIC_HANDSHAKE_TIMEOUT, error_details, | 
 |                   ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 | } | 
 |  | 
 | void QuicConnection::OnIdleNetworkDetected() { | 
 |   const QuicTime::Delta duration = | 
 |       clock_->ApproximateNow() - | 
 |       idle_network_detector_.last_network_activity_time(); | 
 |   std::string error_details = absl::StrCat( | 
 |       "No recent network activity after ", duration.ToDebuggingValue(), | 
 |       ". Timeout:", | 
 |       idle_network_detector_.idle_network_timeout().ToDebuggingValue()); | 
 |   if (perspective() == Perspective::IS_CLIENT && version().UsesTls() && | 
 |       !IsHandshakeComplete()) { | 
 |     absl::StrAppend(&error_details, UndecryptablePacketsInfo()); | 
 |   } | 
 |   QUIC_DVLOG(1) << ENDPOINT << error_details; | 
 |   const bool has_consecutive_pto = | 
 |       sent_packet_manager_.GetConsecutiveTlpCount() > 0 || | 
 |       sent_packet_manager_.GetConsecutiveRtoCount() > 0 || | 
 |       sent_packet_manager_.GetConsecutivePtoCount() > 0; | 
 |   if (has_consecutive_pto || visitor_->ShouldKeepConnectionAlive()) { | 
 |     if (GetQuicReloadableFlag(quic_add_stream_info_to_idle_close_detail) && | 
 |         !has_consecutive_pto) { | 
 |       // Include stream information in error detail if there are open streams. | 
 |       QUIC_RELOADABLE_FLAG_COUNT(quic_add_stream_info_to_idle_close_detail); | 
 |       absl::StrAppend(&error_details, ", ", | 
 |                       visitor_->GetStreamsInfoForLogging()); | 
 |     } | 
 |     CloseConnection(QUIC_NETWORK_IDLE_TIMEOUT, error_details, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return; | 
 |   } | 
 |   QuicErrorCode error_code = QUIC_NETWORK_IDLE_TIMEOUT; | 
 |   if (idle_timeout_connection_close_behavior_ == | 
 |       ConnectionCloseBehavior:: | 
 |           SILENT_CLOSE_WITH_CONNECTION_CLOSE_PACKET_SERIALIZED) { | 
 |     error_code = QUIC_SILENT_IDLE_TIMEOUT; | 
 |   } | 
 |   CloseConnection(error_code, error_details, | 
 |                   idle_timeout_connection_close_behavior_); | 
 | } | 
 |  | 
 | void QuicConnection::OnPeerIssuedConnectionIdRetired() { | 
 |   QUICHE_DCHECK(peer_issued_cid_manager_ != nullptr); | 
 |   QuicConnectionId* default_path_cid = | 
 |       perspective_ == Perspective::IS_CLIENT | 
 |           ? &default_path_.server_connection_id | 
 |           : &default_path_.client_connection_id; | 
 |   QuicConnectionId* alternative_path_cid = | 
 |       perspective_ == Perspective::IS_CLIENT | 
 |           ? &alternative_path_.server_connection_id | 
 |           : &alternative_path_.client_connection_id; | 
 |   bool default_path_and_alternative_path_use_the_same_peer_connection_id = | 
 |       *default_path_cid == *alternative_path_cid; | 
 |   if (!default_path_cid->IsEmpty() && | 
 |       !peer_issued_cid_manager_->IsConnectionIdActive(*default_path_cid)) { | 
 |     *default_path_cid = QuicConnectionId(); | 
 |   } | 
 |   // TODO(haoyuewang) Handle the change for default_path_ & alternatvie_path_ | 
 |   // via the same helper function. | 
 |   if (default_path_cid->IsEmpty()) { | 
 |     // Try setting a new connection ID now such that subsequent | 
 |     // RetireConnectionId frames can be sent on the default path. | 
 |     const QuicConnectionIdData* unused_connection_id_data = | 
 |         peer_issued_cid_manager_->ConsumeOneUnusedConnectionId(); | 
 |     if (unused_connection_id_data != nullptr) { | 
 |       *default_path_cid = unused_connection_id_data->connection_id; | 
 |       default_path_.stateless_reset_token = | 
 |           unused_connection_id_data->stateless_reset_token; | 
 |       if (perspective_ == Perspective::IS_CLIENT) { | 
 |         packet_creator_.SetServerConnectionId( | 
 |             unused_connection_id_data->connection_id); | 
 |       } else { | 
 |         packet_creator_.SetClientConnectionId( | 
 |             unused_connection_id_data->connection_id); | 
 |       } | 
 |     } | 
 |   } | 
 |   if (default_path_and_alternative_path_use_the_same_peer_connection_id) { | 
 |     *alternative_path_cid = *default_path_cid; | 
 |     alternative_path_.stateless_reset_token = | 
 |         default_path_.stateless_reset_token; | 
 |   } else if (!alternative_path_cid->IsEmpty() && | 
 |              !peer_issued_cid_manager_->IsConnectionIdActive( | 
 |                  *alternative_path_cid)) { | 
 |     *alternative_path_cid = EmptyQuicConnectionId(); | 
 |     const QuicConnectionIdData* unused_connection_id_data = | 
 |         peer_issued_cid_manager_->ConsumeOneUnusedConnectionId(); | 
 |     if (unused_connection_id_data != nullptr) { | 
 |       *alternative_path_cid = unused_connection_id_data->connection_id; | 
 |       alternative_path_.stateless_reset_token = | 
 |           unused_connection_id_data->stateless_reset_token; | 
 |     } | 
 |   } | 
 |  | 
 |   std::vector<uint64_t> retired_cid_sequence_numbers = | 
 |       peer_issued_cid_manager_->ConsumeToBeRetiredConnectionIdSequenceNumbers(); | 
 |   QUICHE_DCHECK(!retired_cid_sequence_numbers.empty()); | 
 |   for (const auto& sequence_number : retired_cid_sequence_numbers) { | 
 |     ++stats_.num_retire_connection_id_sent; | 
 |     visitor_->SendRetireConnectionId(sequence_number); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::SendNewConnectionId( | 
 |     const QuicNewConnectionIdFrame& frame) { | 
 |   visitor_->SendNewConnectionId(frame); | 
 |   ++stats_.num_new_connection_id_sent; | 
 |   return connected_; | 
 | } | 
 |  | 
 | void QuicConnection::OnNewConnectionIdIssued( | 
 |     const QuicConnectionId& connection_id) { | 
 |   if (perspective_ == Perspective::IS_SERVER) { | 
 |     visitor_->OnServerConnectionIdIssued(connection_id); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnSelfIssuedConnectionIdRetired( | 
 |     const QuicConnectionId& connection_id) { | 
 |   if (perspective_ == Perspective::IS_SERVER) { | 
 |     visitor_->OnServerConnectionIdRetired(connection_id); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::MaybeUpdateAckTimeout() { | 
 |   if (should_last_packet_instigate_acks_) { | 
 |     return; | 
 |   } | 
 |   should_last_packet_instigate_acks_ = true; | 
 |   uber_received_packet_manager_.MaybeUpdateAckTimeout( | 
 |       /*should_last_packet_instigate_acks=*/true, last_decrypted_packet_level_, | 
 |       last_header_.packet_number, clock_->ApproximateNow(), | 
 |       sent_packet_manager_.GetRttStats()); | 
 | } | 
 |  | 
 | QuicTime QuicConnection::GetPathDegradingDeadline() const { | 
 |   if (!ShouldDetectPathDegrading()) { | 
 |     return QuicTime::Zero(); | 
 |   } | 
 |   return clock_->ApproximateNow() + | 
 |          sent_packet_manager_.GetPathDegradingDelay(); | 
 | } | 
 |  | 
 | bool QuicConnection::ShouldDetectPathDegrading() const { | 
 |   if (!connected_) { | 
 |     return false; | 
 |   } | 
 |   // No path degrading detection before handshake completes. | 
 |   if (!idle_network_detector_.handshake_timeout().IsInfinite()) { | 
 |     return false; | 
 |   } | 
 |   return perspective_ == Perspective::IS_CLIENT && !is_path_degrading_; | 
 | } | 
 |  | 
 | QuicTime QuicConnection::GetNetworkBlackholeDeadline() const { | 
 |   if (!ShouldDetectBlackhole()) { | 
 |     return QuicTime::Zero(); | 
 |   } | 
 |   QUICHE_DCHECK_LT(0u, num_rtos_for_blackhole_detection_); | 
 |   return clock_->ApproximateNow() + | 
 |          sent_packet_manager_.GetNetworkBlackholeDelay( | 
 |              num_rtos_for_blackhole_detection_); | 
 | } | 
 |  | 
 | bool QuicConnection::ShouldDetectBlackhole() const { | 
 |   if (!connected_ || blackhole_detection_disabled_) { | 
 |     return false; | 
 |   } | 
 |   // No blackhole detection before handshake completes. | 
 |   if (default_enable_5rto_blackhole_detection_) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT_N(quic_default_enable_5rto_blackhole_detection2, | 
 |                                  3, 3); | 
 |     return IsHandshakeComplete(); | 
 |   } | 
 |  | 
 |   if (!idle_network_detector_.handshake_timeout().IsInfinite()) { | 
 |     return false; | 
 |   } | 
 |   return num_rtos_for_blackhole_detection_ > 0; | 
 | } | 
 |  | 
 | QuicTime QuicConnection::GetRetransmissionDeadline() const { | 
 |   if (perspective_ == Perspective::IS_CLIENT && | 
 |       SupportsMultiplePacketNumberSpaces() && !IsHandshakeConfirmed() && | 
 |       stats_.pto_count == 0 && | 
 |       !framer_.HasDecrypterOfEncryptionLevel(ENCRYPTION_HANDSHAKE) && | 
 |       !undecryptable_packets_.empty()) { | 
 |     // Retransmits ClientHello quickly when a Handshake or 1-RTT packet is | 
 |     // received prior to having Handshake keys. Adding kAlarmGranulary will | 
 |     // avoid spurious retransmissions in the case of small-scale reordering. | 
 |     return clock_->ApproximateNow() + kAlarmGranularity; | 
 |   } | 
 |   return sent_packet_manager_.GetRetransmissionTime(); | 
 | } | 
 |  | 
 | bool QuicConnection::SendPathChallenge( | 
 |     const QuicPathFrameBuffer& data_buffer, | 
 |     const QuicSocketAddress& self_address, | 
 |     const QuicSocketAddress& peer_address, | 
 |     const QuicSocketAddress& effective_peer_address, | 
 |     QuicPacketWriter* writer) { | 
 |   if (!framer_.HasEncrypterOfEncryptionLevel(ENCRYPTION_FORWARD_SECURE)) { | 
 |     return connected_; | 
 |   } | 
 |   if (connection_migration_use_new_cid_) { | 
 |     { | 
 |       QuicConnectionId client_cid, server_cid; | 
 |       FindOnPathConnectionIds(self_address, effective_peer_address, &client_cid, | 
 |                               &server_cid); | 
 |       QuicPacketCreator::ScopedPeerAddressContext context( | 
 |           &packet_creator_, peer_address, client_cid, server_cid, | 
 |           connection_migration_use_new_cid_); | 
 |       if (writer == writer_) { | 
 |         ScopedPacketFlusher flusher(this); | 
 |         // It's on current path, add the PATH_CHALLENGE the same way as other | 
 |         // frames. This may cause connection to be closed. | 
 |         packet_creator_.AddPathChallengeFrame(data_buffer); | 
 |       } else { | 
 |         std::unique_ptr<SerializedPacket> probing_packet = | 
 |             packet_creator_.SerializePathChallengeConnectivityProbingPacket( | 
 |                 data_buffer); | 
 |         QUICHE_DCHECK_EQ(IsRetransmittable(*probing_packet), | 
 |                          NO_RETRANSMITTABLE_DATA); | 
 |         QUICHE_DCHECK_EQ(self_address, alternative_path_.self_address); | 
 |         WritePacketUsingWriter(std::move(probing_packet), writer, self_address, | 
 |                                peer_address, /*measure_rtt=*/false); | 
 |       } | 
 |     } | 
 |     return connected_; | 
 |   } | 
 |   if (writer == writer_) { | 
 |     ScopedPacketFlusher flusher(this); | 
 |     { | 
 |       // It's on current path, add the PATH_CHALLENGE the same way as other | 
 |       // frames. | 
 |       QuicPacketCreator::ScopedPeerAddressContext context( | 
 |           &packet_creator_, peer_address, /*update_connection_id=*/false); | 
 |       // This may cause connection to be closed. | 
 |       packet_creator_.AddPathChallengeFrame(data_buffer); | 
 |     } | 
 |     // Return outside of the scope so that the flush result can be reflected. | 
 |     return connected_; | 
 |   } | 
 |   std::unique_ptr<SerializedPacket> probing_packet = | 
 |       packet_creator_.SerializePathChallengeConnectivityProbingPacket( | 
 |           data_buffer); | 
 |   QUICHE_DCHECK_EQ(IsRetransmittable(*probing_packet), NO_RETRANSMITTABLE_DATA); | 
 |   QUICHE_DCHECK_EQ(self_address, alternative_path_.self_address); | 
 |   WritePacketUsingWriter(std::move(probing_packet), writer, self_address, | 
 |                          peer_address, /*measure_rtt=*/false); | 
 |   return true; | 
 | } | 
 |  | 
 | QuicTime QuicConnection::GetRetryTimeout( | 
 |     const QuicSocketAddress& peer_address_to_use, | 
 |     QuicPacketWriter* writer_to_use) const { | 
 |   if (writer_to_use == writer_ && peer_address_to_use == peer_address()) { | 
 |     return clock_->ApproximateNow() + sent_packet_manager_.GetPtoDelay(); | 
 |   } | 
 |   return clock_->ApproximateNow() + | 
 |          QuicTime::Delta::FromMilliseconds(3 * kInitialRttMs); | 
 | } | 
 |  | 
 | void QuicConnection::ValidatePath( | 
 |     std::unique_ptr<QuicPathValidationContext> context, | 
 |     std::unique_ptr<QuicPathValidator::ResultDelegate> result_delegate) { | 
 |   QUICHE_DCHECK(use_path_validator_); | 
 |   if (!connection_migration_use_new_cid_ && | 
 |       perspective_ == Perspective::IS_CLIENT && | 
 |       !IsDefaultPath(context->self_address(), context->peer_address())) { | 
 |     alternative_path_ = PathState( | 
 |         context->self_address(), context->peer_address(), | 
 |         default_path_.client_connection_id, default_path_.server_connection_id, | 
 |         default_path_.stateless_reset_token); | 
 |   } | 
 |   if (path_validator_.HasPendingPathValidation()) { | 
 |     // Cancel and fail any earlier validation. | 
 |     path_validator_.CancelPathValidation(); | 
 |   } | 
 |   if (connection_migration_use_new_cid_ && | 
 |       perspective_ == Perspective::IS_CLIENT && | 
 |       !IsDefaultPath(context->self_address(), context->peer_address())) { | 
 |     if (self_issued_cid_manager_ != nullptr) { | 
 |       self_issued_cid_manager_->MaybeSendNewConnectionIds(); | 
 |       if (!connected_) { | 
 |         return; | 
 |       } | 
 |     } | 
 |     if ((self_issued_cid_manager_ != nullptr && | 
 |          !self_issued_cid_manager_->HasConnectionIdToConsume()) || | 
 |         (peer_issued_cid_manager_ != nullptr && | 
 |          !peer_issued_cid_manager_->HasUnusedConnectionId())) { | 
 |       QUIC_DVLOG(1) << "Client cannot start new path validation as there is no " | 
 |                        "requried connection ID is available."; | 
 |       result_delegate->OnPathValidationFailure(std::move(context)); | 
 |       return; | 
 |     } | 
 |     QuicConnectionId client_connection_id, server_connection_id; | 
 |     absl::optional<StatelessResetToken> stateless_reset_token; | 
 |     if (self_issued_cid_manager_ != nullptr) { | 
 |       client_connection_id = | 
 |           *self_issued_cid_manager_->ConsumeOneConnectionId(); | 
 |     } | 
 |     if (peer_issued_cid_manager_ != nullptr) { | 
 |       const auto* connection_id_data = | 
 |           peer_issued_cid_manager_->ConsumeOneUnusedConnectionId(); | 
 |       server_connection_id = connection_id_data->connection_id; | 
 |       stateless_reset_token = connection_id_data->stateless_reset_token; | 
 |     } | 
 |     alternative_path_ = PathState(context->self_address(), | 
 |                                   context->peer_address(), client_connection_id, | 
 |                                   server_connection_id, stateless_reset_token); | 
 |   } | 
 |   path_validator_.StartPathValidation(std::move(context), | 
 |                                       std::move(result_delegate)); | 
 | } | 
 |  | 
 | bool QuicConnection::SendPathResponse( | 
 |     const QuicPathFrameBuffer& data_buffer, | 
 |     const QuicSocketAddress& peer_address_to_send, | 
 |     const QuicSocketAddress& effective_peer_address) { | 
 |   if (!framer_.HasEncrypterOfEncryptionLevel(ENCRYPTION_FORWARD_SECURE)) { | 
 |     return false; | 
 |   } | 
 |   QuicConnectionId client_cid, server_cid; | 
 |   if (connection_migration_use_new_cid_) { | 
 |     FindOnPathConnectionIds(last_received_packet_info_.destination_address, | 
 |                             effective_peer_address, &client_cid, &server_cid); | 
 |   } | 
 |   // Send PATH_RESPONSE using the provided peer address. If the creator has been | 
 |   // using a different peer address, it will flush before and after serializing | 
 |   // the current PATH_RESPONSE. | 
 |   QuicPacketCreator::ScopedPeerAddressContext context( | 
 |       &packet_creator_, peer_address_to_send, client_cid, server_cid, | 
 |       connection_migration_use_new_cid_); | 
 |   QUIC_DVLOG(1) << ENDPOINT << "Send PATH_RESPONSE to " << peer_address_to_send; | 
 |   if (default_path_.self_address == | 
 |       last_received_packet_info_.destination_address) { | 
 |     // The PATH_CHALLENGE is received on the default socket. Respond on the same | 
 |     // socket. | 
 |     return packet_creator_.AddPathResponseFrame(data_buffer); | 
 |   } | 
 |  | 
 |   QUICHE_DCHECK_EQ(Perspective::IS_CLIENT, perspective_); | 
 |   // This PATH_CHALLENGE is received on an alternative socket which should be | 
 |   // used to send PATH_RESPONSE. | 
 |   if (!path_validator_.HasPendingPathValidation() || | 
 |       path_validator_.GetContext()->self_address() != | 
 |           last_received_packet_info_.destination_address) { | 
 |     // Ignore this PATH_CHALLENGE if it's received from an uninteresting | 
 |     // socket. | 
 |     return true; | 
 |   } | 
 |   QuicPacketWriter* writer = path_validator_.GetContext()->WriterToUse(); | 
 |  | 
 |   std::unique_ptr<SerializedPacket> probing_packet = | 
 |       packet_creator_.SerializePathResponseConnectivityProbingPacket( | 
 |           {data_buffer}, /*is_padded=*/true); | 
 |   QUICHE_DCHECK_EQ(IsRetransmittable(*probing_packet), NO_RETRANSMITTABLE_DATA); | 
 |   QUIC_DVLOG(1) << ENDPOINT | 
 |                 << "Send PATH_RESPONSE from alternative socket with address " | 
 |                 << last_received_packet_info_.destination_address; | 
 |   // Ignore the return value to treat write error on the alternative writer as | 
 |   // part of network error. If the writer becomes blocked, wait for the peer to | 
 |   // send another PATH_CHALLENGE. | 
 |   WritePacketUsingWriter(std::move(probing_packet), writer, | 
 |                          last_received_packet_info_.destination_address, | 
 |                          peer_address_to_send, | 
 |                          /*measure_rtt=*/false); | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::UpdatePeerAddress(QuicSocketAddress peer_address) { | 
 |   direct_peer_address_ = peer_address; | 
 |   packet_creator_.SetDefaultPeerAddress(peer_address); | 
 | } | 
 |  | 
 | void QuicConnection::SendPingAtLevel(EncryptionLevel level) { | 
 |   ScopedEncryptionLevelContext context(this, level); | 
 |   SendControlFrame(QuicFrame(QuicPingFrame())); | 
 | } | 
 |  | 
 | bool QuicConnection::HasPendingPathValidation() const { | 
 |   QUICHE_DCHECK(use_path_validator_); | 
 |   return path_validator_.HasPendingPathValidation(); | 
 | } | 
 |  | 
 | QuicPathValidationContext* QuicConnection::GetPathValidationContext() const { | 
 |   QUICHE_DCHECK(use_path_validator_); | 
 |   return path_validator_.GetContext(); | 
 | } | 
 |  | 
 | void QuicConnection::CancelPathValidation() { | 
 |   QUICHE_DCHECK(use_path_validator_); | 
 |   path_validator_.CancelPathValidation(); | 
 | } | 
 |  | 
 | bool QuicConnection::UpdateConnectionIdsOnClientMigration( | 
 |     const QuicSocketAddress& self_address, | 
 |     const QuicSocketAddress& peer_address) { | 
 |   QUICHE_DCHECK(perspective_ == Perspective::IS_CLIENT); | 
 |   if (IsAlternativePath(self_address, peer_address)) { | 
 |     // Client migration is after path validation. | 
 |     default_path_.client_connection_id = alternative_path_.client_connection_id; | 
 |     default_path_.server_connection_id = alternative_path_.server_connection_id; | 
 |     default_path_.stateless_reset_token = | 
 |         alternative_path_.stateless_reset_token; | 
 |     return true; | 
 |   } | 
 |   // Client migration is without path validation. | 
 |   if (self_issued_cid_manager_ != nullptr) { | 
 |     self_issued_cid_manager_->MaybeSendNewConnectionIds(); | 
 |     if (!connected_) { | 
 |       return false; | 
 |     } | 
 |   } | 
 |   if ((self_issued_cid_manager_ != nullptr && | 
 |        !self_issued_cid_manager_->HasConnectionIdToConsume()) || | 
 |       (peer_issued_cid_manager_ != nullptr && | 
 |        !peer_issued_cid_manager_->HasUnusedConnectionId())) { | 
 |     return false; | 
 |   } | 
 |   if (self_issued_cid_manager_ != nullptr) { | 
 |     default_path_.client_connection_id = | 
 |         *self_issued_cid_manager_->ConsumeOneConnectionId(); | 
 |   } | 
 |   if (peer_issued_cid_manager_ != nullptr) { | 
 |     const auto* connection_id_data = | 
 |         peer_issued_cid_manager_->ConsumeOneUnusedConnectionId(); | 
 |     default_path_.server_connection_id = connection_id_data->connection_id; | 
 |     default_path_.stateless_reset_token = | 
 |         connection_id_data->stateless_reset_token; | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::RetirePeerIssuedConnectionIdsNoLongerOnPath() { | 
 |   if (!connection_migration_use_new_cid_ || | 
 |       peer_issued_cid_manager_ == nullptr) { | 
 |     return; | 
 |   } | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     peer_issued_cid_manager_->MaybeRetireUnusedConnectionIds( | 
 |         {default_path_.server_connection_id, | 
 |          alternative_path_.server_connection_id}); | 
 |   } else { | 
 |     peer_issued_cid_manager_->MaybeRetireUnusedConnectionIds( | 
 |         {default_path_.client_connection_id, | 
 |          alternative_path_.client_connection_id}); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::MigratePath(const QuicSocketAddress& self_address, | 
 |                                  const QuicSocketAddress& peer_address, | 
 |                                  QuicPacketWriter* writer, | 
 |                                  bool owns_writer) { | 
 |   QUICHE_DCHECK(perspective_ == Perspective::IS_CLIENT); | 
 |   if (!connected_) { | 
 |     if (owns_writer) { | 
 |       delete writer; | 
 |     } | 
 |     return false; | 
 |   } | 
 |   QUICHE_DCHECK(!version().UsesHttp3() || IsHandshakeConfirmed()); | 
 |  | 
 |   if (connection_migration_use_new_cid_) { | 
 |     if (!UpdateConnectionIdsOnClientMigration(self_address, peer_address)) { | 
 |       if (owns_writer) { | 
 |         delete writer; | 
 |       } | 
 |       return false; | 
 |     } | 
 |     if (packet_creator_.GetServerConnectionId().length() != | 
 |         default_path_.server_connection_id.length()) { | 
 |       packet_creator_.FlushCurrentPacket(); | 
 |     } | 
 |     packet_creator_.SetClientConnectionId(default_path_.client_connection_id); | 
 |     packet_creator_.SetServerConnectionId(default_path_.server_connection_id); | 
 |   } | 
 |  | 
 |   const auto self_address_change_type = QuicUtils::DetermineAddressChangeType( | 
 |       default_path_.self_address, self_address); | 
 |   const auto peer_address_change_type = QuicUtils::DetermineAddressChangeType( | 
 |       default_path_.peer_address, peer_address); | 
 |   QUICHE_DCHECK(self_address_change_type != NO_CHANGE || | 
 |                 peer_address_change_type != NO_CHANGE); | 
 |   const bool is_port_change = (self_address_change_type == PORT_CHANGE || | 
 |                                self_address_change_type == NO_CHANGE) && | 
 |                               (peer_address_change_type == PORT_CHANGE || | 
 |                                peer_address_change_type == NO_CHANGE); | 
 |   SetSelfAddress(self_address); | 
 |   UpdatePeerAddress(peer_address); | 
 |   SetQuicPacketWriter(writer, owns_writer); | 
 |   MaybeClearQueuedPacketsOnPathChange(); | 
 |   OnSuccessfulMigration(is_port_change); | 
 |   return true; | 
 | } | 
 |  | 
 | void QuicConnection::OnPathValidationFailureAtClient() { | 
 |   if (connection_migration_use_new_cid_) { | 
 |     QUICHE_DCHECK(perspective_ == Perspective::IS_CLIENT); | 
 |     alternative_path_.Clear(); | 
 |   } | 
 |   // The alarm to retire connection IDs no longer on paths is scheduled at the | 
 |   // end of writing and reading packet. On path validation failure, there could | 
 |   // be no packet to write or read. Hence the retirement alarm for the | 
 |   // connection ID associated with the failed path needs to be proactively | 
 |   // scheduled here. | 
 |   RetirePeerIssuedConnectionIdsNoLongerOnPath(); | 
 | } | 
 |  | 
 | QuicConnectionId QuicConnection::GetOneActiveServerConnectionId() const { | 
 |   if (perspective_ == Perspective::IS_CLIENT || | 
 |       self_issued_cid_manager_ == nullptr) { | 
 |     return connection_id(); | 
 |   } | 
 |   auto active_connection_ids = GetActiveServerConnectionIds(); | 
 |   QUIC_BUG_IF(quic_bug_6944, active_connection_ids.empty()); | 
 |   if (active_connection_ids.empty() || | 
 |       std::find(active_connection_ids.begin(), active_connection_ids.end(), | 
 |                 connection_id()) != active_connection_ids.end()) { | 
 |     return connection_id(); | 
 |   } | 
 |   QUICHE_CODE_COUNT(connection_id_on_default_path_has_been_retired); | 
 |   auto active_connection_id = | 
 |       self_issued_cid_manager_->GetOneActiveConnectionId(); | 
 |   return active_connection_id; | 
 | } | 
 |  | 
 | std::vector<QuicConnectionId> QuicConnection::GetActiveServerConnectionIds() | 
 |     const { | 
 |   if (self_issued_cid_manager_ == nullptr) { | 
 |     return {default_path_.server_connection_id}; | 
 |   } | 
 |   QUICHE_DCHECK(version().HasIetfQuicFrames()); | 
 |   return self_issued_cid_manager_->GetUnretiredConnectionIds(); | 
 | } | 
 |  | 
 | void QuicConnection::CreateConnectionIdManager() { | 
 |   if (!version().HasIetfQuicFrames()) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     if (!default_path_.server_connection_id.IsEmpty()) { | 
 |       peer_issued_cid_manager_ = | 
 |           std::make_unique<QuicPeerIssuedConnectionIdManager>( | 
 |               kMinNumOfActiveConnectionIds, default_path_.server_connection_id, | 
 |               clock_, alarm_factory_, this, context()); | 
 |     } | 
 |   } else { | 
 |     if (!default_path_.server_connection_id.IsEmpty()) { | 
 |       self_issued_cid_manager_ = MakeSelfIssuedConnectionIdManager(); | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::SetUnackedMapInitialCapacity() { | 
 |   sent_packet_manager_.ReserveUnackedPacketsInitialCapacity( | 
 |       GetUnackedMapInitialCapacity()); | 
 | } | 
 |  | 
 | void QuicConnection::SetSourceAddressTokenToSend(absl::string_view token) { | 
 |   QUICHE_DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |   if (!packet_creator_.HasRetryToken()) { | 
 |     // Ignore received tokens (via NEW_TOKEN frame) from previous connections | 
 |     // when a RETRY token has been received. | 
 |     packet_creator_.SetRetryToken(std::string(token.data(), token.length())); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::MaybeUpdateBytesSentToAlternativeAddress( | 
 |     const QuicSocketAddress& peer_address, | 
 |     QuicByteCount sent_packet_size) { | 
 |   if (!version().SupportsAntiAmplificationLimit() || | 
 |       perspective_ != Perspective::IS_SERVER) { | 
 |     return; | 
 |   } | 
 |   QUICHE_DCHECK(!IsDefaultPath(default_path_.self_address, peer_address)); | 
 |   if (!IsAlternativePath(default_path_.self_address, peer_address)) { | 
 |     QUIC_DLOG(INFO) << "Wrote to uninteresting peer address: " << peer_address | 
 |                     << " default direct_peer_address_ " << direct_peer_address_ | 
 |                     << " alternative path peer address " | 
 |                     << alternative_path_.peer_address; | 
 |     return; | 
 |   } | 
 |   if (alternative_path_.validated) { | 
 |     return; | 
 |   } | 
 |   if (alternative_path_.bytes_sent_before_address_validation >= | 
 |       anti_amplification_factor_ * | 
 |           alternative_path_.bytes_received_before_address_validation) { | 
 |     QUIC_LOG_FIRST_N(WARNING, 100) | 
 |         << "Server sent more data than allowed to unverified alternative " | 
 |            "peer address " | 
 |         << peer_address << " bytes sent " | 
 |         << alternative_path_.bytes_sent_before_address_validation | 
 |         << ", bytes received " | 
 |         << alternative_path_.bytes_received_before_address_validation; | 
 |   } | 
 |   alternative_path_.bytes_sent_before_address_validation += sent_packet_size; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeUpdateBytesReceivedFromAlternativeAddress( | 
 |     QuicByteCount received_packet_size) { | 
 |   if (!version().SupportsAntiAmplificationLimit() || | 
 |       perspective_ != Perspective::IS_SERVER || | 
 |       !IsAlternativePath(last_received_packet_info_.destination_address, | 
 |                          GetEffectivePeerAddressFromCurrentPacket()) || | 
 |       last_received_packet_info_.received_bytes_counted) { | 
 |     return; | 
 |   } | 
 |   // Only update bytes received if this probing frame is received on the most | 
 |   // recent alternative path. | 
 |   QUICHE_DCHECK(!IsDefaultPath(last_received_packet_info_.destination_address, | 
 |                                GetEffectivePeerAddressFromCurrentPacket())); | 
 |   if (!alternative_path_.validated) { | 
 |     alternative_path_.bytes_received_before_address_validation += | 
 |         received_packet_size; | 
 |   } | 
 |   last_received_packet_info_.received_bytes_counted = true; | 
 | } | 
 |  | 
 | bool QuicConnection::IsDefaultPath( | 
 |     const QuicSocketAddress& self_address, | 
 |     const QuicSocketAddress& peer_address) const { | 
 |   return direct_peer_address_ == peer_address && | 
 |          default_path_.self_address == self_address; | 
 | } | 
 |  | 
 | bool QuicConnection::IsAlternativePath( | 
 |     const QuicSocketAddress& self_address, | 
 |     const QuicSocketAddress& peer_address) const { | 
 |   return alternative_path_.peer_address == peer_address && | 
 |          alternative_path_.self_address == self_address; | 
 | } | 
 |  | 
 | void QuicConnection::PathState::Clear() { | 
 |   self_address = QuicSocketAddress(); | 
 |   peer_address = QuicSocketAddress(); | 
 |   client_connection_id = {}; | 
 |   server_connection_id = {}; | 
 |   validated = false; | 
 |   bytes_received_before_address_validation = 0; | 
 |   bytes_sent_before_address_validation = 0; | 
 |   send_algorithm = nullptr; | 
 |   rtt_stats = absl::nullopt; | 
 |   stateless_reset_token.reset(); | 
 | } | 
 |  | 
 | QuicConnection::PathState::PathState(PathState&& other) { | 
 |   *this = std::move(other); | 
 | } | 
 |  | 
 | QuicConnection::PathState& QuicConnection::PathState::operator=( | 
 |     QuicConnection::PathState&& other) { | 
 |   if (this != &other) { | 
 |     self_address = other.self_address; | 
 |     peer_address = other.peer_address; | 
 |     client_connection_id = other.client_connection_id; | 
 |     server_connection_id = other.server_connection_id; | 
 |     stateless_reset_token = other.stateless_reset_token; | 
 |     validated = other.validated; | 
 |     bytes_received_before_address_validation = | 
 |         other.bytes_received_before_address_validation; | 
 |     bytes_sent_before_address_validation = | 
 |         other.bytes_sent_before_address_validation; | 
 |     send_algorithm = std::move(other.send_algorithm); | 
 |     if (other.rtt_stats.has_value()) { | 
 |       rtt_stats.emplace(); | 
 |       rtt_stats->CloneFrom(other.rtt_stats.value()); | 
 |     } else { | 
 |       rtt_stats.reset(); | 
 |     } | 
 |     other.Clear(); | 
 |   } | 
 |   return *this; | 
 | } | 
 |  | 
 | bool QuicConnection::IsReceivedPeerAddressValidated() const { | 
 |   QuicSocketAddress current_effective_peer_address = | 
 |       GetEffectivePeerAddressFromCurrentPacket(); | 
 |   QUICHE_DCHECK(current_effective_peer_address.IsInitialized()); | 
 |   return (alternative_path_.peer_address.host() == | 
 |               current_effective_peer_address.host() && | 
 |           alternative_path_.validated) || | 
 |          (default_path_.validated && default_path_.peer_address.host() == | 
 |                                          current_effective_peer_address.host()); | 
 | } | 
 |  | 
 | QuicConnection::ReversePathValidationResultDelegate:: | 
 |     ReversePathValidationResultDelegate( | 
 |         QuicConnection* connection, | 
 |         const QuicSocketAddress& direct_peer_address) | 
 |     : QuicPathValidator::ResultDelegate(), | 
 |       connection_(connection), | 
 |       original_direct_peer_address_(direct_peer_address), | 
 |       peer_address_default_path_(connection->direct_peer_address_), | 
 |       peer_address_alternative_path_( | 
 |           connection_->alternative_path_.peer_address), | 
 |       active_effective_peer_migration_type_( | 
 |           connection_->active_effective_peer_migration_type_) {} | 
 |  | 
 | void QuicConnection::ReversePathValidationResultDelegate:: | 
 |     OnPathValidationSuccess( | 
 |         std::unique_ptr<QuicPathValidationContext> context) { | 
 |   QUIC_DLOG(INFO) << "Successfully validated new path " << *context; | 
 |   if (connection_->IsDefaultPath(context->self_address(), | 
 |                                  context->peer_address())) { | 
 |     QUIC_CODE_COUNT_N(quic_kick_off_client_address_validation, 3, 6); | 
 |     if (connection_->active_effective_peer_migration_type_ == NO_CHANGE) { | 
 |       connection_->quic_bug_10511_43_timestamp_ = | 
 |           connection_->clock_->WallNow(); | 
 |       connection_->quic_bug_10511_43_error_detail_ = absl::StrCat( | 
 |           "Reverse path validation on default path from ", | 
 |           context->self_address().ToString(), " to ", | 
 |           context->peer_address().ToString(), | 
 |           " completed without active peer address change: current " | 
 |           "peer address on default path ", | 
 |           connection_->direct_peer_address_.ToString(), | 
 |           ", peer address on default path when the reverse path " | 
 |           "validation was kicked off ", | 
 |           peer_address_default_path_.ToString(), | 
 |           ", peer address on alternative path when the reverse " | 
 |           "path validation was kicked off ", | 
 |           peer_address_alternative_path_.ToString(), | 
 |           ", with active_effective_peer_migration_type_ = ", | 
 |           AddressChangeTypeToString(active_effective_peer_migration_type_), | 
 |           ". The last received packet number ", | 
 |           connection_->last_header_.packet_number.ToString(), | 
 |           " Connection is connected: ", connection_->connected_); | 
 |       QUIC_BUG(quic_bug_10511_43) | 
 |           << connection_->quic_bug_10511_43_error_detail_; | 
 |     } | 
 |     connection_->OnEffectivePeerMigrationValidated(); | 
 |   } else { | 
 |     QUICHE_DCHECK(connection_->IsAlternativePath( | 
 |         context->self_address(), context->effective_peer_address())); | 
 |     QUIC_CODE_COUNT_N(quic_kick_off_client_address_validation, 4, 6); | 
 |     QUIC_DVLOG(1) << "Mark alternative peer address " | 
 |                   << context->effective_peer_address() << " validated."; | 
 |     connection_->alternative_path_.validated = true; | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::ReversePathValidationResultDelegate:: | 
 |     OnPathValidationFailure( | 
 |         std::unique_ptr<QuicPathValidationContext> context) { | 
 |   if (!connection_->connected()) { | 
 |     return; | 
 |   } | 
 |   QUIC_DLOG(INFO) << "Fail to validate new path " << *context; | 
 |   if (connection_->IsDefaultPath(context->self_address(), | 
 |                                  context->peer_address())) { | 
 |     // Only act upon validation failure on the default path. | 
 |     QUIC_CODE_COUNT_N(quic_kick_off_client_address_validation, 5, 6); | 
 |     connection_->RestoreToLastValidatedPath(original_direct_peer_address_); | 
 |   } else if (connection_->IsAlternativePath( | 
 |                  context->self_address(), context->effective_peer_address())) { | 
 |     QUIC_CODE_COUNT_N(quic_kick_off_client_address_validation, 6, 6); | 
 |     connection_->alternative_path_.Clear(); | 
 |   } | 
 | } | 
 |  | 
 | QuicConnection::ScopedRetransmissionTimeoutIndicator:: | 
 |     ScopedRetransmissionTimeoutIndicator(QuicConnection* connection) | 
 |     : connection_(connection) { | 
 |   QUICHE_DCHECK(!connection_->in_on_retransmission_time_out_) | 
 |       << "ScopedRetransmissionTimeoutIndicator is not supposed to be nested"; | 
 |   connection_->in_on_retransmission_time_out_ = true; | 
 | } | 
 |  | 
 | QuicConnection::ScopedRetransmissionTimeoutIndicator:: | 
 |     ~ScopedRetransmissionTimeoutIndicator() { | 
 |   QUICHE_DCHECK(connection_->in_on_retransmission_time_out_); | 
 |   connection_->in_on_retransmission_time_out_ = false; | 
 | } | 
 |  | 
 | void QuicConnection::RestoreToLastValidatedPath( | 
 |     QuicSocketAddress original_direct_peer_address) { | 
 |   QUIC_DLOG(INFO) << "Switch back to use the old peer address " | 
 |                   << alternative_path_.peer_address; | 
 |   if (!alternative_path_.validated) { | 
 |     // If not validated by now, close connection silently so that the following | 
 |     // packets received will be rejected. | 
 |     CloseConnection(QUIC_INTERNAL_ERROR, | 
 |                     "No validated peer address to use after reverse path " | 
 |                     "validation failure.", | 
 |                     ConnectionCloseBehavior::SILENT_CLOSE); | 
 |     return; | 
 |   } | 
 |   MaybeClearQueuedPacketsOnPathChange(); | 
 |  | 
 |   // Revert congestion control context to old state. | 
 |   OnPeerIpAddressChanged(); | 
 |  | 
 |   if (alternative_path_.send_algorithm != nullptr) { | 
 |     sent_packet_manager_.SetSendAlgorithm( | 
 |         alternative_path_.send_algorithm.release()); | 
 |     sent_packet_manager_.SetRttStats(alternative_path_.rtt_stats.value()); | 
 |   } else { | 
 |     QUIC_BUG(quic_bug_10511_42) | 
 |         << "Fail to store congestion controller before migration."; | 
 |   } | 
 |  | 
 |   UpdatePeerAddress(original_direct_peer_address); | 
 |   SetDefaultPathState(std::move(alternative_path_)); | 
 |  | 
 |   active_effective_peer_migration_type_ = NO_CHANGE; | 
 |   ++stats_.num_invalid_peer_migration; | 
 |   // The reverse path validation failed because of alarm firing, flush all the | 
 |   // pending writes previously throttled by anti-amplification limit. | 
 |   WriteIfNotBlocked(); | 
 | } | 
 |  | 
 | std::unique_ptr<SendAlgorithmInterface> | 
 | QuicConnection::OnPeerIpAddressChanged() { | 
 |   QUICHE_DCHECK(validate_client_addresses_); | 
 |   std::unique_ptr<SendAlgorithmInterface> old_send_algorithm = | 
 |       sent_packet_manager_.OnConnectionMigration( | 
 |           /*reset_send_algorithm=*/true); | 
 |   // OnConnectionMigration() should have marked in-flight packets to be | 
 |   // retransmitted if there is any. | 
 |   QUICHE_DCHECK(!sent_packet_manager_.HasInFlightPackets()); | 
 |   // OnConnectionMigration() may have changed the retransmission timer, so | 
 |   // re-arm it. | 
 |   SetRetransmissionAlarm(); | 
 |   // Stop detections in quiecense. | 
 |   blackhole_detector_.StopDetection(/*permanent=*/false); | 
 |   return old_send_algorithm; | 
 | } | 
 |  | 
 | #undef ENDPOINT  // undef for jumbo builds | 
 | }  // namespace quic |