| // 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 "net/third_party/quiche/src/quic/core/quic_connection.h" | 
 |  | 
 | #include <string.h> | 
 | #include <sys/types.h> | 
 |  | 
 | #include <algorithm> | 
 | #include <iterator> | 
 | #include <limits> | 
 | #include <memory> | 
 | #include <set> | 
 | #include <string> | 
 | #include <utility> | 
 |  | 
 | #include "net/third_party/quiche/src/quic/core/crypto/crypto_protocol.h" | 
 | #include "net/third_party/quiche/src/quic/core/crypto/crypto_utils.h" | 
 | #include "net/third_party/quiche/src/quic/core/crypto/quic_decrypter.h" | 
 | #include "net/third_party/quiche/src/quic/core/crypto/quic_encrypter.h" | 
 | #include "net/third_party/quiche/src/quic/core/proto/cached_network_parameters_proto.h" | 
 | #include "net/third_party/quiche/src/quic/core/quic_bandwidth.h" | 
 | #include "net/third_party/quiche/src/quic/core/quic_config.h" | 
 | #include "net/third_party/quiche/src/quic/core/quic_connection_id.h" | 
 | #include "net/third_party/quiche/src/quic/core/quic_constants.h" | 
 | #include "net/third_party/quiche/src/quic/core/quic_error_codes.h" | 
 | #include "net/third_party/quiche/src/quic/core/quic_legacy_version_encapsulator.h" | 
 | #include "net/third_party/quiche/src/quic/core/quic_types.h" | 
 | #include "net/third_party/quiche/src/quic/core/quic_utils.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_bug_tracker.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_client_stats.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_error_code_wrappers.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_exported_stats.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_flag_utils.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_flags.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_hostname_utils.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_logging.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_map_util.h" | 
 | #include "net/third_party/quiche/src/quic/platform/api/quic_string_utils.h" | 
 | #include "net/third_party/quiche/src/common/platform/api/quiche_str_cat.h" | 
 | #include "net/third_party/quiche/src/common/platform/api/quiche_string_piece.h" | 
 | #include "net/third_party/quiche/src/common/platform/api/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; | 
 |  | 
 | // An alarm that is scheduled to send an ack if a timeout occurs. | 
 | class AckAlarmDelegate : public QuicAlarm::Delegate { | 
 |  public: | 
 |   explicit AckAlarmDelegate(QuicConnection* connection) | 
 |       : connection_(connection) {} | 
 |   AckAlarmDelegate(const AckAlarmDelegate&) = delete; | 
 |   AckAlarmDelegate& operator=(const AckAlarmDelegate&) = delete; | 
 |  | 
 |   void OnAlarm() override { | 
 |     DCHECK(connection_->ack_frame_updated()); | 
 |     QuicConnection::ScopedPacketFlusher flusher(connection_); | 
 |     if (connection_->SupportsMultiplePacketNumberSpaces()) { | 
 |       connection_->SendAllPendingAcks(); | 
 |     } else { | 
 |       connection_->SendAck(); | 
 |     } | 
 |   } | 
 |  | 
 |  private: | 
 |   QuicConnection* connection_; | 
 | }; | 
 |  | 
 | // 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 QuicAlarm::Delegate { | 
 |  public: | 
 |   explicit RetransmissionAlarmDelegate(QuicConnection* connection) | 
 |       : connection_(connection) {} | 
 |   RetransmissionAlarmDelegate(const RetransmissionAlarmDelegate&) = delete; | 
 |   RetransmissionAlarmDelegate& operator=(const RetransmissionAlarmDelegate&) = | 
 |       delete; | 
 |  | 
 |   void OnAlarm() override { connection_->OnRetransmissionTimeout(); } | 
 |  | 
 |  private: | 
 |   QuicConnection* connection_; | 
 | }; | 
 |  | 
 | // 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 QuicAlarm::Delegate { | 
 |  public: | 
 |   explicit SendAlarmDelegate(QuicConnection* connection) | 
 |       : connection_(connection) {} | 
 |   SendAlarmDelegate(const SendAlarmDelegate&) = delete; | 
 |   SendAlarmDelegate& operator=(const SendAlarmDelegate&) = delete; | 
 |  | 
 |   void OnAlarm() override { connection_->WriteAndBundleAcksIfNotBlocked(); } | 
 |  | 
 |  private: | 
 |   QuicConnection* connection_; | 
 | }; | 
 |  | 
 | class PingAlarmDelegate : public QuicAlarm::Delegate { | 
 |  public: | 
 |   explicit PingAlarmDelegate(QuicConnection* connection) | 
 |       : connection_(connection) {} | 
 |   PingAlarmDelegate(const PingAlarmDelegate&) = delete; | 
 |   PingAlarmDelegate& operator=(const PingAlarmDelegate&) = delete; | 
 |  | 
 |   void OnAlarm() override { connection_->OnPingTimeout(); } | 
 |  | 
 |  private: | 
 |   QuicConnection* connection_; | 
 | }; | 
 |  | 
 | class MtuDiscoveryAlarmDelegate : public QuicAlarm::Delegate { | 
 |  public: | 
 |   explicit MtuDiscoveryAlarmDelegate(QuicConnection* connection) | 
 |       : connection_(connection) {} | 
 |   MtuDiscoveryAlarmDelegate(const MtuDiscoveryAlarmDelegate&) = delete; | 
 |   MtuDiscoveryAlarmDelegate& operator=(const MtuDiscoveryAlarmDelegate&) = | 
 |       delete; | 
 |  | 
 |   void OnAlarm() override { connection_->DiscoverMtu(); } | 
 |  | 
 |  private: | 
 |   QuicConnection* connection_; | 
 | }; | 
 |  | 
 | class ProcessUndecryptablePacketsAlarmDelegate : public QuicAlarm::Delegate { | 
 |  public: | 
 |   explicit ProcessUndecryptablePacketsAlarmDelegate(QuicConnection* connection) | 
 |       : connection_(connection) {} | 
 |   ProcessUndecryptablePacketsAlarmDelegate( | 
 |       const ProcessUndecryptablePacketsAlarmDelegate&) = delete; | 
 |   ProcessUndecryptablePacketsAlarmDelegate& operator=( | 
 |       const ProcessUndecryptablePacketsAlarmDelegate&) = delete; | 
 |  | 
 |   void OnAlarm() override { | 
 |     QuicConnection::ScopedPacketFlusher flusher(connection_); | 
 |     connection_->MaybeProcessUndecryptablePackets(); | 
 |   } | 
 |  | 
 |  private: | 
 |   QuicConnection* connection_; | 
 | }; | 
 |  | 
 | // 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 PacketCanReplaceConnectionId(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_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), | 
 |       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()), | 
 |       server_connection_id_(server_connection_id), | 
 |       client_connection_id_(EmptyQuicConnectionId()), | 
 |       client_connection_id_is_set_(false), | 
 |       peer_address_(initial_peer_address), | 
 |       direct_peer_address_(initial_peer_address), | 
 |       active_effective_peer_migration_type_(NO_CHANGE), | 
 |       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)), | 
 |       pending_version_negotiation_packet_(false), | 
 |       send_ietf_version_negotiation_packet_(false), | 
 |       send_version_negotiation_packet_with_prefixed_lengths_(false), | 
 |       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), | 
 |       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_)), | 
 |       visitor_(nullptr), | 
 |       debug_visitor_(nullptr), | 
 |       packet_creator_(server_connection_id_, &framer_, random_generator_, this), | 
 |       time_of_last_received_packet_(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_( | 
 |           VersionHasIetfInvariantHeader(transport_version())), | 
 |       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), | 
 |       stateless_reset_token_received_(false), | 
 |       received_stateless_reset_token_(0), | 
 |       last_control_frame_id_(kInvalidControlFrameId), | 
 |       is_path_degrading_(false), | 
 |       processing_ack_frame_(false), | 
 |       supports_release_time_(false), | 
 |       release_time_into_future_(QuicTime::Delta::Zero()), | 
 |       drop_incoming_retry_packets_(false), | 
 |       bytes_received_before_address_validation_(0), | 
 |       bytes_sent_before_address_validation_(0), | 
 |       address_validated_(false), | 
 |       blackhole_detector_(this, &arena_, alarm_factory_), | 
 |       idle_network_detector_(this, | 
 |                              clock_->ApproximateNow(), | 
 |                              &arena_, | 
 |                              alarm_factory_), | 
 |       support_handshake_done_(version().HasHandshakeDone()) { | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "Created connection with server connection ID " | 
 |                   << server_connection_id | 
 |                   << " and version: " << ParsedQuicVersionToString(version()); | 
 |  | 
 |   QUIC_BUG_IF(!QuicUtils::IsConnectionIdValidForVersion(server_connection_id, | 
 |                                                         transport_version())) | 
 |       << "QuicConnection: attempted to use server connection ID " | 
 |       << server_connection_id << " which is invalid with version " | 
 |       << QuicVersionToString(transport_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(); | 
 |   DCHECK(perspective_ == Perspective::IS_CLIENT || | 
 |          supported_versions.size() == 1); | 
 |   InstallInitialCrypters(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; | 
 |   } | 
 | } | 
 |  | 
 | 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() { | 
 |   if (owns_writer_) { | 
 |     delete writer_; | 
 |   } | 
 |   ClearQueuedPackets(); | 
 | } | 
 |  | 
 | void QuicConnection::ClearQueuedPackets() { | 
 |   buffered_packets_.clear(); | 
 | } | 
 |  | 
 | bool QuicConnection::ValidateConfigConnectionIdsOld(const QuicConfig& config) { | 
 |   // This function validates connection IDs as defined in IETF draft-27 and | 
 |   // earlier. | 
 |   DCHECK(config.negotiated()); | 
 |   DCHECK(!version().AuthenticatesHandshakeConnectionIds()); | 
 |   if (original_destination_connection_id_.has_value() && | 
 |       retry_source_connection_id_.has_value()) { | 
 |     DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |     // We received a RETRY packet, validate that the original destination | 
 |     // connection ID from the config matches the one from the RETRY. | 
 |     if (!config.HasReceivedOriginalConnectionId() || | 
 |         config.ReceivedOriginalConnectionId() != | 
 |             original_destination_connection_id_.value()) { | 
 |       std::string received_value; | 
 |       if (config.HasReceivedOriginalConnectionId()) { | 
 |         received_value = config.ReceivedOriginalConnectionId().ToString(); | 
 |       } else { | 
 |         received_value = "none"; | 
 |       } | 
 |       std::string error_details = quiche::QuicheStrCat( | 
 |           "Bad original_connection_id: expected ", | 
 |           original_destination_connection_id_.value().ToString(), ", received ", | 
 |           received_value, ", RETRY used ", server_connection_id_.ToString()); | 
 |       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 | 
 |     // original_destination_connection_id transport parameter. | 
 |     if (config.HasReceivedOriginalConnectionId()) { | 
 |       std::string error_details = quiche::QuicheStrCat( | 
 |           "Bad original_connection_id: did not receive RETRY but received ", | 
 |           config.ReceivedOriginalConnectionId().ToString()); | 
 |       CloseConnection(IETF_QUIC_PROTOCOL_VIOLATION, error_details, | 
 |                       ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |       return false; | 
 |     } | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::ValidateConfigConnectionIds(const QuicConfig& config) { | 
 |   DCHECK(config.negotiated()); | 
 |   if (!version().UsesTls()) { | 
 |     // QUIC+TLS is required to transmit connection ID transport parameters. | 
 |     return true; | 
 |   } | 
 |   if (!version().AuthenticatesHandshakeConnectionIds()) { | 
 |     return ValidateConfigConnectionIdsOld(config); | 
 |   } | 
 |   // 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 = server_connection_id_; | 
 |   } else { | 
 |     expected_initial_source_connection_id = 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 = | 
 |         quiche::QuicheStrCat("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 = quiche::QuicheStrCat( | 
 |           "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 = | 
 |             quiche::QuicheStrCat("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 = quiche::QuicheStrCat( | 
 |             "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 (!ValidateConfigConnectionIds(config)) { | 
 |       return; | 
 |     } | 
 |   } else { | 
 |     SetNetworkTimeouts(config.max_time_before_crypto_handshake(), | 
 |                        config.max_idle_time_before_crypto_handshake()); | 
 |   } | 
 |   if (config.HandshakeDoneSupported()) { | 
 |     support_handshake_done_ = true; | 
 |   } | 
 |  | 
 |   sent_packet_manager_.SetFromConfig(config); | 
 |   if (config.HasReceivedBytesForConnectionId() && | 
 |       can_truncate_connection_ids_) { | 
 |     packet_creator_.SetServerConnectionIdLength( | 
 |         config.ReceivedBytesForConnectionId()); | 
 |   } | 
 |   max_undecryptable_packets_ = config.max_undecryptable_packets(); | 
 |  | 
 |   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 (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()) { | 
 |     stateless_reset_token_received_ = true; | 
 |     received_stateless_reset_token_ = config.ReceivedStatelessResetToken(); | 
 |   } | 
 |   if (config.HasReceivedAckDelayExponent()) { | 
 |     framer_.set_peer_ack_delay_exponent(config.ReceivedAckDelayExponent()); | 
 |   } | 
 |   if (GetQuicReloadableFlag(quic_send_timestamps) && | 
 |       config.HasClientSentConnectionOption(kSTMP, perspective_)) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT(quic_send_timestamps); | 
 |     framer_.set_process_timestamps(true); | 
 |     uber_received_packet_manager_.set_save_timestamps(true); | 
 |   } | 
 |   if (config.HasClientSentConnectionOption(kEACK, perspective_)) { | 
 |     bundle_retransmittable_with_pto_ack_ = true; | 
 |   } | 
 |   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 << "Cannot enable Legacy Version Encapsulation on the server"; | 
 |     return; | 
 |   } | 
 |   if (legacy_version_encapsulation_enabled_) { | 
 |     QUIC_BUG << "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; | 
 | } | 
 |  | 
 | 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(); | 
 | } | 
 |  | 
 | 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 (QuicContainsValue(available_versions, version)) { | 
 |       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.) | 
 |   DCHECK_EQ(server_connection_id_, packet.connection_id); | 
 |   DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |   DCHECK(!VersionHasIetfInvariantHeader(transport_version())); | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPublicResetPacket(packet); | 
 |   } | 
 |   std::string error_details = "Received public reset."; | 
 |   if (perspective_ == Perspective::IS_CLIENT && !packet.endpoint_id.empty()) { | 
 |     QuicStrAppend(&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, 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 << 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.) | 
 |   DCHECK_EQ(server_connection_id_, packet.connection_id); | 
 |   if (perspective_ == Perspective::IS_SERVER) { | 
 |     const std::string error_details = | 
 |         "Server received version negotiation packet."; | 
 |     QUIC_BUG << 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 (QuicContainsValue(packet.versions, version())) { | 
 |     const std::string error_details = quiche::QuicheStrCat( | 
 |         "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, | 
 |       quiche::QuicheStrCat( | 
 |           "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, | 
 |     quiche::QuicheStringPiece retry_token, | 
 |     quiche::QuicheStringPiece retry_integrity_tag, | 
 |     quiche::QuicheStringPiece retry_without_tag) { | 
 |   DCHECK_EQ(Perspective::IS_CLIENT, perspective_); | 
 |   if (version().HasRetryIntegrityTag()) { | 
 |     if (!CryptoUtils::ValidateRetryIntegrityTag( | 
 |             version(), server_connection_id_, retry_without_tag, | 
 |             retry_integrity_tag)) { | 
 |       QUIC_DLOG(ERROR) << "Ignoring RETRY with invalid integrity tag"; | 
 |       return; | 
 |     } | 
 |   } else { | 
 |     if (original_connection_id != server_connection_id_) { | 
 |       QUIC_DLOG(ERROR) << "Ignoring RETRY with original connection ID " | 
 |                        << original_connection_id << " not matching expected " | 
 |                        << server_connection_id_ << " token " | 
 |                        << quiche::QuicheTextUtils::HexEncode(retry_token); | 
 |       return; | 
 |     } | 
 |   } | 
 |   if (drop_incoming_retry_packets_) { | 
 |     QUIC_DLOG(ERROR) << "Ignoring RETRY with token " | 
 |                      << quiche::QuicheTextUtils::HexEncode(retry_token); | 
 |     return; | 
 |   } | 
 |   drop_incoming_retry_packets_ = true; | 
 |   stats_.retry_packet_processed = true; | 
 |   QUIC_DLOG(INFO) << "Received RETRY, replacing connection ID " | 
 |                   << server_connection_id_ << " with " << new_connection_id | 
 |                   << ", received token " | 
 |                   << quiche::QuicheTextUtils::HexEncode(retry_token); | 
 |   if (!original_destination_connection_id_.has_value()) { | 
 |     original_destination_connection_id_ = server_connection_id_; | 
 |   } | 
 |   DCHECK(!retry_source_connection_id_.has_value()) | 
 |       << retry_source_connection_id_.value(); | 
 |   retry_source_connection_id_ = new_connection_id; | 
 |   server_connection_id_ = new_connection_id; | 
 |   packet_creator_.SetServerConnectionId(server_connection_id_); | 
 |   packet_creator_.SetRetryToken(retry_token); | 
 |  | 
 |   // Reinstall initial crypters because the connection ID changed. | 
 |   InstallInitialCrypters(server_connection_id_); | 
 | } | 
 |  | 
 | bool QuicConnection::HasIncomingConnectionId(QuicConnectionId connection_id) { | 
 |   for (QuicConnectionId const& incoming_connection_id : | 
 |        incoming_connection_ids_) { | 
 |     if (incoming_connection_id == connection_id) { | 
 |       return true; | 
 |     } | 
 |   } | 
 |   return false; | 
 | } | 
 |  | 
 | 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 " | 
 |                   << server_connection_id_; | 
 |   DCHECK_NE(original_destination_connection_id, server_connection_id_); | 
 |   if (!HasIncomingConnectionId(original_destination_connection_id)) { | 
 |     incoming_connection_ids_.push_back(original_destination_connection_id); | 
 |   } | 
 |   InstallInitialCrypters(original_destination_connection_id); | 
 |   DCHECK(!original_destination_connection_id_.has_value()) | 
 |       << original_destination_connection_id_.value(); | 
 |   original_destination_connection_id_ = original_destination_connection_id; | 
 | } | 
 |  | 
 | QuicConnectionId QuicConnection::GetOriginalDestinationConnectionId() { | 
 |   if (original_destination_connection_id_.has_value()) { | 
 |     return original_destination_connection_id_.value(); | 
 |   } | 
 |   return server_connection_id_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnUnauthenticatedPublicHeader( | 
 |     const QuicPacketHeader& header) { | 
 |   // As soon as we receive an initial we start ignoring subsequent retries. | 
 |   if (header.version_flag && header.long_packet_type == INITIAL) { | 
 |     drop_incoming_retry_packets_ = true; | 
 |   } | 
 |  | 
 |   QuicConnectionId server_connection_id = | 
 |       GetServerConnectionIdAsRecipient(header, perspective_); | 
 |  | 
 |   if (server_connection_id != server_connection_id_ && | 
 |       !HasIncomingConnectionId(server_connection_id)) { | 
 |     if (PacketCanReplaceConnectionId(header, perspective_)) { | 
 |       QUIC_DLOG(INFO) << ENDPOINT << "Accepting packet with new connection ID " | 
 |                       << server_connection_id << " instead of " | 
 |                       << server_connection_id_; | 
 |       return true; | 
 |     } | 
 |  | 
 |     ++stats_.packets_dropped; | 
 |     QUIC_DLOG(INFO) << ENDPOINT | 
 |                     << "Ignoring packet from unexpected server connection ID " | 
 |                     << server_connection_id << " instead of " | 
 |                     << 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. | 
 |     DCHECK_NE(Perspective::IS_SERVER, perspective_); | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (!version().SupportsClientConnectionIds()) { | 
 |     return true; | 
 |   } | 
 |  | 
 |   QuicConnectionId client_connection_id = | 
 |       GetClientConnectionIdAsRecipient(header, perspective_); | 
 |  | 
 |   if (client_connection_id == 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; | 
 |   } | 
 |  | 
 |   ++stats_.packets_dropped; | 
 |   QUIC_DLOG(INFO) << ENDPOINT | 
 |                   << "Ignoring packet from unexpected client connection ID " | 
 |                   << client_connection_id << " instead of " | 
 |                   << client_connection_id_; | 
 |   return false; | 
 | } | 
 |  | 
 | bool QuicConnection::OnUnauthenticatedHeader(const QuicPacketHeader& header) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnUnauthenticatedHeader(header); | 
 |   } | 
 |  | 
 |   // Check that any public reset packet with a different connection ID that was | 
 |   // routed to this QuicConnection has been redirected before control reaches | 
 |   // here. | 
 |   DCHECK(GetServerConnectionIdAsRecipient(header, perspective_) == | 
 |              server_connection_id_ || | 
 |          HasIncomingConnectionId( | 
 |              GetServerConnectionIdAsRecipient(header, perspective_)) || | 
 |          PacketCanReplaceConnectionId(header, perspective_)); | 
 |  | 
 |   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 << 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::OnSuccessfulMigrationAfterProbing() { | 
 |   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(); | 
 |   } | 
 |   // TODO(b/159074035): notify SentPacketManger with RTT sample from probing and | 
 |   // reset cwnd if this is a successful network migration. | 
 | } | 
 |  | 
 | 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); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::HasPendingAcks() const { | 
 |   return ack_alarm_->IsSet(); | 
 | } | 
 |  | 
 | void QuicConnection::OnDecryptedPacket(EncryptionLevel level) { | 
 |   last_decrypted_packet_level_ = level; | 
 |   last_packet_decrypted_ = true; | 
 |   if (EnforceAntiAmplificationLimit() && | 
 |       last_decrypted_packet_level_ >= ENCRYPTION_HANDSHAKE) { | 
 |     // Address is validated by successfully processing a HANDSHAKE packet. | 
 |     address_validated_ = true; | 
 |   } | 
 |   idle_network_detector_.OnPacketReceived(time_of_last_received_packet_); | 
 |  | 
 |   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_packet_source_address_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnPacketHeader(const QuicPacketHeader& header) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPacketHeader(header); | 
 |   } | 
 |  | 
 |   // 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. | 
 |   current_packet_content_ = NO_FRAMES_RECEIVED; | 
 |   is_current_packet_connectivity_probing_ = false; | 
 |   current_effective_peer_migration_type_ = NO_CHANGE; | 
 |  | 
 |   if (perspective_ == Perspective::IS_CLIENT) { | 
 |     if (!GetLargestReceivedPacket().IsInitialized() || | 
 |         header.packet_number > GetLargestReceivedPacket()) { | 
 |       // Update peer_address_ and effective_peer_address_ immediately for | 
 |       // client connections. | 
 |       // TODO(fayang): only change peer addresses in application data packet | 
 |       // number space. | 
 |       direct_peer_address_ = last_packet_source_address_; | 
 |       effective_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( | 
 |             effective_peer_address_, | 
 |             GetEffectivePeerAddressFromCurrentPacket()); | 
 |  | 
 |     QUIC_DLOG_IF(INFO, current_effective_peer_migration_type_ != NO_CHANGE) | 
 |         << ENDPOINT << "Effective peer's ip:port changed from " | 
 |         << effective_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. | 
 |   uber_received_packet_manager_.RecordPacketReceived( | 
 |       last_decrypted_packet_level_, last_header_, | 
 |       idle_network_detector_.time_of_last_received_packet()); | 
 |   DCHECK(connected_); | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnStreamFrame(const QuicStreamFrame& frame) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a stream frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   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 << 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; | 
 |   } | 
 |   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) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a CRYPTO frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   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) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   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. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   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) { | 
 |   DCHECK(connected_); | 
 |   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) { | 
 |   DCHECK(connected_); | 
 |   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) { | 
 |   DCHECK(connected_); | 
 |   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 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(); | 
 |   } | 
 |   // 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) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a stop waiting frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   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) { | 
 |   DCHECK(connected_); | 
 |   UpdatePacketContent(SECOND_FRAME_IS_PADDING); | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPaddingFrame(frame); | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnPingFrame(const QuicPingFrame& frame) { | 
 |   DCHECK(connected_); | 
 |   UpdatePacketContent(FIRST_FRAME_IS_PING); | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPingFrame(frame); | 
 |   } | 
 |   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) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a reset stream frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   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) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a reset stream frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnStopSendingFrame(frame); | 
 |   } | 
 |  | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "STOP_SENDING frame received for stream: " | 
 |                   << frame.stream_id | 
 |                   << " with error: " << frame.application_error_code; | 
 |  | 
 |   visitor_->OnStopSendingFrame(frame); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnPathChallengeFrame(const QuicPathChallengeFrame& frame) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPathChallengeFrame(frame); | 
 |   } | 
 |   // 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; | 
 | } | 
 |  | 
 | bool QuicConnection::OnPathResponseFrame(const QuicPathResponseFrame& frame) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPathResponseFrame(frame); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   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 true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnConnectionCloseFrame( | 
 |     const QuicConnectionCloseFrame& frame) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a connection close frame was received, this is not a connectivity | 
 |   // probe. A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   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: " << 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) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnMaxStreamsFrame(frame); | 
 |   } | 
 |   return visitor_->OnMaxStreamsFrame(frame) && connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnStreamsBlockedFrame( | 
 |     const QuicStreamsBlockedFrame& frame) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnStreamsBlockedFrame(frame); | 
 |   } | 
 |   return visitor_->OnStreamsBlockedFrame(frame) && connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnGoAwayFrame(const QuicGoAwayFrame& frame) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a go away frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   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) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a window update frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   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_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnNewConnectionIdFrame( | 
 |     const QuicNewConnectionIdFrame& frame) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnNewConnectionIdFrame(frame); | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnRetireConnectionIdFrame( | 
 |     const QuicRetireConnectionIdFrame& frame) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnRetireConnectionIdFrame(frame); | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnNewTokenFrame(const QuicNewTokenFrame& frame) { | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnNewTokenFrame(frame); | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | bool QuicConnection::OnMessageFrame(const QuicMessageFrame& frame) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a message frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnMessageFrame(frame); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnMessageReceived( | 
 |       quiche::QuicheStringPiece(frame.data, frame.message_length)); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnHandshakeDoneFrame(const QuicHandshakeDoneFrame& frame) { | 
 |   DCHECK(connected_); | 
 |   if (!support_handshake_done_) { | 
 |     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. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnHandshakeDoneFrame(frame); | 
 |   } | 
 |   MaybeUpdateAckTimeout(); | 
 |   visitor_->OnHandshakeDoneReceived(); | 
 |   return connected_; | 
 | } | 
 |  | 
 | bool QuicConnection::OnAckFrequencyFrame( | 
 |     const QuicAckFrequencyFrame& /*frame*/) { | 
 |   // TODO(b/148614353): implement this fully. | 
 |   QUIC_LOG_EVERY_N_SEC(ERROR, 120) << "Get unexpected AckFrequencyFrame."; | 
 |   return false; | 
 | } | 
 | bool QuicConnection::OnBlockedFrame(const QuicBlockedFrame& frame) { | 
 |   DCHECK(connected_); | 
 |  | 
 |   // Since a blocked frame was received, this is not a connectivity probe. | 
 |   // A probe only contains a PING and full padding. | 
 |   UpdatePacketContent(NOT_PADDED_PING); | 
 |  | 
 |   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()) { | 
 |     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(); | 
 |  | 
 |   if (IsCurrentPacketConnectivityProbing()) { | 
 |     DCHECK(!version().HasIetfQuicFrames()); | 
 |     visitor_->OnPacketReceived(last_packet_destination_address_, | 
 |                                last_packet_source_address_, | 
 |                                /*is_connectivity_probe=*/true); | 
 |   } else 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_packet_source_address_.ToString() | 
 |                   << " to ip:port: " | 
 |                   << last_packet_destination_address_.ToString(); | 
 |     visitor_->OnPacketReceived(last_packet_destination_address_, | 
 |                                last_packet_source_address_, | 
 |                                /*is_connectivity_probe=*/false); | 
 |   } else if (version().HasIetfQuicFrames() && | 
 |              !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_packet_source_address_, | 
 |                                /* is_response=*/true); | 
 |   } else if (last_header_.packet_number == GetLargestReceivedPacket()) { | 
 |     direct_peer_address_ = last_packet_source_address_; | 
 |     if (current_effective_peer_migration_type_ != NO_CHANGE) { | 
 |       // TODO(fayang): When multiple packet number spaces is supported, only | 
 |       // start peer migration for the application data. | 
 |       StartEffectivePeerMigration(current_effective_peer_migration_type_); | 
 |     } | 
 |   } | 
 |  | 
 |   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, | 
 |         idle_network_detector_.time_of_last_received_packet(), | 
 |         clock_->ApproximateNow(), sent_packet_manager_.GetRttStats()); | 
 |   } | 
 |  | 
 |   ClearLastFrames(); | 
 |   CloseIfTooManyOutstandingSentPackets(); | 
 | } | 
 |  | 
 | bool QuicConnection::IsValidStatelessResetToken(QuicUint128 token) const { | 
 |   return stateless_reset_token_received_ && | 
 |          token == received_stateless_reset_token_; | 
 | } | 
 |  | 
 | void QuicConnection::OnAuthenticatedIetfStatelessResetPacket( | 
 |     const QuicIetfStatelessResetPacket& /*packet*/) { | 
 |   // TODO(fayang): Add OnAuthenticatedIetfStatelessResetPacket to | 
 |   // debug_visitor_. | 
 |   DCHECK(VersionHasIetfInvariantHeader(transport_version())); | 
 |   DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |   if (!visitor_->ValidateStatelessReset(last_packet_destination_address_, | 
 |                                         last_packet_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, error_details, | 
 |                                ConnectionCloseSource::FROM_PEER); | 
 | } | 
 |  | 
 | 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. | 
 |   if (sent_packet_manager_.GetLargestObserved().IsInitialized() && | 
 |       sent_packet_manager_.GetLargestObserved() > | 
 |           sent_packet_manager_.GetLeastUnacked() + max_tracked_packets_) { | 
 |     CloseConnection( | 
 |         QUIC_TOO_MANY_OUTSTANDING_SENT_PACKETS, | 
 |         quiche::QuicheStrCat( | 
 |             "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() { | 
 |   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 { | 
 |     WriteAndBundleAcksIfNotBlocked(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::SendVersionNegotiationPacket(bool ietf_quic, | 
 |                                                   bool has_length_prefix) { | 
 |   pending_version_negotiation_packet_ = true; | 
 |   send_ietf_version_negotiation_packet_ = ietf_quic; | 
 |   send_version_negotiation_packet_with_prefixed_lengths_ = has_length_prefix; | 
 |  | 
 |   if (HandleWriteBlocked()) { | 
 |     return; | 
 |   } | 
 |  | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "Sending version negotiation packet: {" | 
 |                   << ParsedQuicVersionVectorToString( | 
 |                          framer_.supported_versions()) | 
 |                   << "}, " << (ietf_quic ? "" : "!") << "ietf_quic"; | 
 |   std::unique_ptr<QuicEncryptedPacket> version_packet( | 
 |       packet_creator_.SerializeVersionNegotiationPacket( | 
 |           ietf_quic, has_length_prefix, framer_.supported_versions())); | 
 |   QUIC_DVLOG(2) << ENDPOINT << "Sending version negotiation packet: {" | 
 |                 << ParsedQuicVersionVectorToString(framer_.supported_versions()) | 
 |                 << "}, " << (ietf_quic ? "" : "!") << "ietf_quic:" << std::endl | 
 |                 << quiche::QuicheTextUtils::HexDump(quiche::QuicheStringPiece( | 
 |                        version_packet->data(), version_packet->length())); | 
 |   WriteResult result = writer_->WritePacket( | 
 |       version_packet->data(), version_packet->length(), self_address().host(), | 
 |       peer_address(), per_packet_options_); | 
 |  | 
 |   if (IsWriteError(result.status)) { | 
 |     OnWriteError(result.error_code); | 
 |     return; | 
 |   } | 
 |   if (IsWriteBlockedStatus(result.status)) { | 
 |     visitor_->OnWriteBlocked(); | 
 |     if (result.status == WRITE_STATUS_BLOCKED_DATA_BUFFERED) { | 
 |       pending_version_negotiation_packet_ = false; | 
 |     } | 
 |     return; | 
 |   } | 
 |  | 
 |   pending_version_negotiation_packet_ = false; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeActivateLegacyVersionEncapsulation() { | 
 |   if (!legacy_version_encapsulation_enabled_) { | 
 |     return; | 
 |   } | 
 |   DCHECK(!legacy_version_encapsulation_in_progress_); | 
 |   QUIC_BUG_IF(!packet_creator_.CanSetMaxPacketLength()) | 
 |       << "Cannot activate Legacy Version Encapsulation mid-packet"; | 
 |   QUIC_BUG_IF(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(); | 
 |   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 << "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 << "Attempt to send empty stream frame"; | 
 |     return QuicConsumedData(0, false); | 
 |   } | 
 |  | 
 |   if (packet_creator_.encryption_level() == ENCRYPTION_INITIAL && | 
 |       QuicUtils::IsCryptoStreamId(transport_version(), id)) { | 
 |     MaybeActivateLegacyVersionEncapsulation(); | 
 |   } | 
 |   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(); | 
 |     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_.max_packet_size = packet_creator_.max_packet_length(); | 
 |   stats_.max_received_packet_size = 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_; | 
 |   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); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::ShouldEnqueueUnDecryptablePacket( | 
 |     EncryptionLevel decryption_level, | 
 |     bool has_decryption_key) const { | 
 |   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE) { | 
 |     // 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 (has_decryption_key) { | 
 |     // We already have the key for this decryption level, therefore no | 
 |     // future keys will allow it be decrypted. | 
 |     return false; | 
 |   } | 
 |   if (version().KnowsWhichDecrypterToUse() && | 
 |       decryption_level <= encryption_level_) { | 
 |     // On versions that know which decrypter to use, we install keys in order | 
 |     // so we will not get newer keys for lower encryption levels. | 
 |     return false; | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | std::string QuicConnection::UndecryptablePacketsInfo() const { | 
 |   std::string info = quiche::QuicheStrCat( | 
 |       "num_undecryptable_packets: ", undecryptable_packets_.size(), " {"); | 
 |   for (const auto& packet : undecryptable_packets_) { | 
 |     info = quiche::QuicheStrCat( | 
 |         info, "[", EncryptionLevelToString(packet.encryption_level), ", ", | 
 |         packet.packet->length(), ", ", packet.processed, "]"); | 
 |   } | 
 |   info = quiche::QuicheStrCat(info, "}"); | 
 |   return info; | 
 | } | 
 |  | 
 | void QuicConnection::MaybeUpdatePacketCreatorMaxPacketLengthAndPadding() { | 
 |   QuicByteCount max_packet_length = GetLimitedMaxPacketSize(long_term_mtu_); | 
 |   if (legacy_version_encapsulation_in_progress_) { | 
 |     DCHECK(legacy_version_encapsulation_enabled_); | 
 |     const QuicByteCount minimum_overhead = | 
 |         QuicLegacyVersionEncapsulator::GetMinimumOverhead( | 
 |             legacy_version_encapsulation_sni_); | 
 |     if (max_packet_length < minimum_overhead) { | 
 |       QUIC_BUG << "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); | 
 |   if (legacy_version_encapsulation_enabled_) { | 
 |     packet_creator_.set_disable_padding_override( | 
 |         legacy_version_encapsulation_in_progress_); | 
 |   } | 
 | } | 
 |  | 
 | 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(quiche::QuicheStringPiece( | 
 |                        packet.data(), packet.length())); | 
 |   QUIC_BUG_IF(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_size_ = packet.length(); | 
 |   current_packet_data_ = packet.data(); | 
 |  | 
 |   last_packet_destination_address_ = self_address; | 
 |   last_packet_source_address_ = peer_address; | 
 |   if (!self_address_.IsInitialized()) { | 
 |     self_address_ = last_packet_destination_address_; | 
 |   } | 
 |  | 
 |   if (!direct_peer_address_.IsInitialized()) { | 
 |     direct_peer_address_ = last_packet_source_address_; | 
 |   } | 
 |  | 
 |   if (!effective_peer_address_.IsInitialized()) { | 
 |     const QuicSocketAddress effective_peer_addr = | 
 |         GetEffectivePeerAddressFromCurrentPacket(); | 
 |  | 
 |     // effective_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. | 
 |     effective_peer_address_ = effective_peer_addr.IsInitialized() | 
 |                                   ? effective_peer_addr | 
 |                                   : direct_peer_address_; | 
 |   } | 
 |  | 
 |   stats_.bytes_received += packet.length(); | 
 |   ++stats_.packets_received; | 
 |   if (EnforceAntiAmplificationLimit()) { | 
 |     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 << "Packet receipt time:" | 
 |              << packet.receipt_time().ToDebuggingValue() | 
 |              << " too far from current time:" | 
 |              << clock_->ApproximateNow().ToDebuggingValue(); | 
 |   } | 
 |   time_of_last_received_packet_ = packet.receipt_time(); | 
 |   QUIC_DVLOG(1) << ENDPOINT << "time of last received packet: " | 
 |                 << packet.receipt_time().ToDebuggingValue(); | 
 |  | 
 |   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 (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(); | 
 |     } | 
 |   } | 
 |  | 
 |   MaybeProcessCoalescedPackets(); | 
 |   MaybeProcessUndecryptablePackets(); | 
 |   MaybeSendInResponseToPacket(); | 
 |   SetPingAlarm(); | 
 |   current_packet_data_ = nullptr; | 
 |   is_current_packet_connectivity_probing_ = false; | 
 | } | 
 |  | 
 | void QuicConnection::OnBlockedWriterCanWrite() { | 
 |   writer_->SetWritable(); | 
 |   OnCanWrite(); | 
 | } | 
 |  | 
 | void QuicConnection::OnCanWrite() { | 
 |   if (!connected_) { | 
 |     return; | 
 |   } | 
 |   DCHECK(!writer_->IsWriteBlocked()); | 
 |  | 
 |   // Add a flusher to ensure the connection is marked app-limited. | 
 |   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(); | 
 |     } | 
 |   } | 
 |  | 
 |   WriteNewData(); | 
 | } | 
 |  | 
 | void QuicConnection::WriteNewData() { | 
 |   // Sending queued packets may have caused the socket to become write blocked, | 
 |   // or the congestion manager to prohibit sending.  If we've sent everything | 
 |   // we had queued and we're still not blocked, let the visitor know it can | 
 |   // write more. | 
 |   if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) { | 
 |     return; | 
 |   } | 
 |  | 
 |   { | 
 |     ScopedPacketFlusher flusher(this); | 
 |     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 stream didn't write out all of its | 
 |     // bytes. Register for 'immediate' resumption so we'll keep writing after | 
 |     // other connections and events have had a chance to use the thread. | 
 |     send_alarm_->Set(clock_->ApproximateNow()); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::WriteIfNotBlocked() { | 
 |   if (!HandleWriteBlocked()) { | 
 |     OnCanWrite(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::WriteAndBundleAcksIfNotBlocked() { | 
 |   if (!HandleWriteBlocked()) { | 
 |     ScopedPacketFlusher flusher(this); | 
 |     WriteIfNotBlocked(); | 
 |   } | 
 | } | 
 |  | 
 | bool QuicConnection::ProcessValidatedPacket(const QuicPacketHeader& header) { | 
 |   if (perspective_ == Perspective::IS_SERVER && self_address_.IsInitialized() && | 
 |       last_packet_destination_address_.IsInitialized() && | 
 |       self_address_ != last_packet_destination_address_) { | 
 |     // Allow change between pure IPv4 and equivalent mapped IPv4 address. | 
 |     if (self_address_.port() != last_packet_destination_address_.port() || | 
 |         self_address_.host().Normalized() != | 
 |             last_packet_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; | 
 |       } | 
 |     } | 
 |     self_address_ = last_packet_destination_address_; | 
 |   } | 
 |  | 
 |   if (PacketCanReplaceConnectionId(header, perspective_) && | 
 |       server_connection_id_ != header.source_connection_id) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Replacing connection ID " | 
 |                     << server_connection_id_ << " with " | 
 |                     << header.source_connection_id; | 
 |     if (!original_destination_connection_id_.has_value()) { | 
 |       original_destination_connection_id_ = server_connection_id_; | 
 |     } | 
 |     server_connection_id_ = header.source_connection_id; | 
 |     packet_creator_.SetServerConnectionId(server_connection_id_); | 
 |   } | 
 |  | 
 |   if (!ValidateReceivedPacketNumber(header.packet_number)) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (!version_negotiated_) { | 
 |     if (perspective_ == Perspective::IS_CLIENT) { | 
 |       DCHECK(!header.version_flag || header.form != GOOGLE_QUIC_PACKET); | 
 |       if (!VersionHasIetfInvariantHeader(framer_.transport_version())) { | 
 |         // 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()) { | 
 |     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() { | 
 |   DCHECK(!writer_->IsWriteBlocked()); | 
 |  | 
 |   if (pending_version_negotiation_packet_) { | 
 |     SendVersionNegotiationPacket( | 
 |         send_ietf_version_negotiation_packet_, | 
 |         send_version_negotiation_packet_with_prefixed_lengths_); | 
 |   } | 
 |  | 
 |   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::RetransmitZeroRttPackets() { | 
 |   sent_packet_manager_.RetransmitZeroRttPackets(); | 
 |  | 
 |   if (!GetQuicReloadableFlag( | 
 |           quic_do_not_retransmit_immediately_on_zero_rtt_reject)) { | 
 |     WriteIfNotBlocked(); | 
 |   } | 
 | } | 
 |  | 
 | 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) { | 
 |   DCHECK(handshake != IS_HANDSHAKE || | 
 |          QuicVersionUsesCryptoFrames(transport_version())) | 
 |       << ENDPOINT | 
 |       << "Handshake in STREAM frames should not check ShouldGeneratePacket"; | 
 |   // We should serialize handshake packets immediately to ensure that they | 
 |   // end up sent at the right encryption level. | 
 |   if (!move_amplification_limit_ && handshake == IS_HANDSHAKE) { | 
 |     if (LimitedByAmplificationFactor()) { | 
 |       // Server is constrained by the amplification restriction. | 
 |       QUIC_DVLOG(1) << ENDPOINT << "Constrained by amplification restriction"; | 
 |       return false; | 
 |     } | 
 |     return true; | 
 |   } | 
 |  | 
 |   return CanWrite(retransmittable); | 
 | } | 
 |  | 
 | const QuicFrames QuicConnection::MaybeBundleAckOpportunistically() { | 
 |   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(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 (move_amplification_limit_ && LimitedByAmplificationFactor()) { | 
 |     // Server is constrained by the amplification restriction. | 
 |     QUIC_RELOADABLE_FLAG_COUNT(quic_move_amplification_limit); | 
 |     QUIC_CODE_COUNT(quic_throttled_by_amplification_limit); | 
 |     QUIC_DVLOG(1) << ENDPOINT << "Constrained by amplification restriction"; | 
 |     return false; | 
 |   } | 
 |  | 
 |   if (sent_packet_manager_.pending_timer_transmission_count() > 0) { | 
 |     // Force sending the retransmissions for HANDSHAKE, TLP, RTO, PROBING cases. | 
 |     return true; | 
 |   } | 
 |  | 
 |   if (HandleWriteBlocked()) { | 
 |     return false; | 
 |   } | 
 |  | 
 |   // Allow acks 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 (!packet_creator_.determine_serialized_packet_fate_early() && | 
 |       ShouldDiscardPacket(packet->encryption_level)) { | 
 |     ++stats_.packets_discarded; | 
 |     return true; | 
 |   } | 
 |   if (sent_packet_manager_.GetLargestSentPacket().IsInitialized() && | 
 |       packet->packet_number < sent_packet_manager_.GetLargestSentPacket()) { | 
 |     QUIC_BUG << "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_creator_.determine_serialized_packet_fate_early() | 
 |           ? packet->fate | 
 |           : GetSerializedPacketFate(is_mtu_discovery, packet->encryption_level); | 
 |   // Termination packets are encrypted and saved, so don't exit early. | 
 |   const bool is_termination_packet = IsTerminationPacket(*packet); | 
 |   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)); | 
 |   } | 
 |  | 
 |   DCHECK_LE(encrypted_length, kMaxOutgoingPacketSize); | 
 |   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 only ") | 
 |                 << ", encryption level: " << packet->encryption_level | 
 |                 << ", encrypted length:" << encrypted_length | 
 |                 << ", fate: " << fate; | 
 |   QUIC_DVLOG(2) << ENDPOINT << packet->encryption_level << " packet number " | 
 |                 << packet_number << " of length " << encrypted_length << ": " | 
 |                 << std::endl | 
 |                 << quiche::QuicheTextUtils::HexDump(quiche::QuicheStringPiece( | 
 |                        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); | 
 |   switch (fate) { | 
 |     case DISCARD: | 
 |       DCHECK(packet_creator_.determine_serialized_packet_fate_early()); | 
 |       ++stats_.packets_discarded; | 
 |       return true; | 
 |     case COALESCE: | 
 |       QUIC_BUG_IF(!version().CanSendCoalescedPackets()); | 
 |       if (!coalesced_packet_.MaybeCoalescePacket( | 
 |               *packet, self_address(), peer_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(), peer_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(), peer_address()); | 
 |       break; | 
 |     case SEND_TO_WRITER: | 
 |       // 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(), peer_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 FAILED_TO_WRITE_COALESCED_PACKET: | 
 |       // Failed to send existing coalesced packet when determining packet fate, | 
 |       // write error has been handled. | 
 |       QUIC_BUG_IF(!version().CanSendCoalescedPackets()); | 
 |       return false; | 
 |     case LEGACY_VERSION_ENCAPSULATE: { | 
 |       DCHECK(!is_mtu_discovery); | 
 |       DCHECK_EQ(perspective_, Perspective::IS_CLIENT); | 
 |       DCHECK_EQ(packet->encryption_level, ENCRYPTION_INITIAL); | 
 |       DCHECK(legacy_version_encapsulation_enabled_); | 
 |       DCHECK(legacy_version_encapsulation_in_progress_); | 
 |       QuicPacketLength encapsulated_length = | 
 |           QuicLegacyVersionEncapsulator::Encapsulate( | 
 |               legacy_version_encapsulation_sni_, | 
 |               quiche::QuicheStringPiece(packet->encrypted_buffer, | 
 |                                         packet->encrypted_length), | 
 |               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(quiche::QuicheStringPiece( | 
 |                    packet->encrypted_buffer, encrypted_length)); | 
 |       } else { | 
 |         QUIC_BUG << 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(), peer_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(), | 
 |                                       peer_address(), per_packet_options_); | 
 |       } | 
 |     } break; | 
 |     default: | 
 |       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. | 
 |     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(), peer_address()); | 
 |     } | 
 |   } | 
 |  | 
 |   // In some cases, an MTU probe can cause EMSGSIZE. This indicates that the | 
 |   // MTU discovery is permanently unsuccessful. | 
 |   if (IsMsgTooBig(result) && 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 (IsWriteError(result.status)) { | 
 |     QUIC_LOG_FIRST_N(ERROR, 10) | 
 |         << ENDPOINT << "Failed writing packet " << packet_number << " of " | 
 |         << encrypted_length << " bytes from " << self_address().host() << " to " | 
 |         << peer_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 (ShouldIgnoreWriteError()) { | 
 |       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. | 
 |     DCHECK((per_packet_options_ && per_packet_options_->allow_burst) || | 
 |            result.send_time_offset.IsZero()); | 
 |     packet_send_time = packet_send_time + result.send_time_offset; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     // Pass the write result to the visitor. | 
 |     debug_visitor_->OnPacketSent(*packet, packet->transmission_type, | 
 |                                  packet_send_time); | 
 |   } | 
 |   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()); | 
 |     } | 
 |     idle_network_detector_.OnPacketSent(packet_send_time); | 
 |   } | 
 |  | 
 |   MaybeSetMtuAlarm(packet_number); | 
 |   QUIC_DVLOG(1) << ENDPOINT << "time we began writing last sent packet: " | 
 |                 << packet_send_time.ToDebuggingValue(); | 
 |  | 
 |   if (EnforceAntiAmplificationLimit()) { | 
 |     // Include bytes sent even if they are not in flight. | 
 |     bytes_sent_before_address_validation_ += encrypted_length; | 
 |   } | 
 |  | 
 |   const bool in_flight = sent_packet_manager_.OnPacketSent( | 
 |       packet, packet_send_time, packet->transmission_type, | 
 |       IsRetransmittable(*packet)); | 
 |   QUIC_BUG_IF(default_enable_5rto_blackhole_detection_ && | 
 |               blackhole_detector_.IsDetectionInProgress() && | 
 |               !sent_packet_manager_.HasInFlightPackets()) | 
 |       << ENDPOINT | 
 |       << "Trying to start blackhole detection without no bytes in flight"; | 
 |  | 
 |   if (in_flight || !retransmission_alarm_->IsSet()) { | 
 |     SetRetransmissionAlarm(); | 
 |   } | 
 |   SetPingAlarm(); | 
 |  | 
 |   // 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_.GetLeastUnacked(), | 
 |       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; | 
 | } | 
 |  | 
 | 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()) { | 
 |     DCHECK_EQ(WRITE_STATUS_BLOCKED, result.status) | 
 |         << "Unexpected flush result:" << result; | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Write blocked in FlushPackets."; | 
 |     return; | 
 |   } | 
 |  | 
 |   if (IsWriteError(result.status) && !ShouldIgnoreWriteError()) { | 
 |     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; | 
 | } | 
 |  | 
 | bool QuicConnection::ShouldIgnoreWriteError() { | 
 |   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 = quiche::QuicheStrCat( | 
 |       "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 (VersionHasIetfInvariantHeader(transport_version())) { | 
 |         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() && !IsHandshakeConfirmed()) { | 
 |     // 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 (VersionHasIetfInvariantHeader(transport_version())) { | 
 |       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 (VersionHasIetfInvariantHeader(transport_version())) { | 
 |     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()); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::OnHandshakeComplete() { | 
 |   sent_packet_manager_.SetHandshakeConfirmed(); | 
 |   // 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_->SendPing(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::SendAck() { | 
 |   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() { | 
 | #ifndef NDEBUG | 
 |   if (sent_packet_manager_.unacked_packets().empty()) { | 
 |     DCHECK(sent_packet_manager_.handshake_mode_disabled()); | 
 |     DCHECK(!IsHandshakeComplete()); | 
 |   } | 
 | #endif | 
 |  | 
 |   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_.GetLeastUnacked(), | 
 |         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); | 
 |     } | 
 |   } | 
 |   if (default_enable_5rto_blackhole_detection_ && | 
 |       !sent_packet_manager_.HasInFlightPackets() && | 
 |       blackhole_detector_.IsDetectionInProgress()) { | 
 |     // Stop detection in quiescence. | 
 |     DCHECK_EQ(QuicSentPacketManager::LOSS_MODE, retransmission_mode); | 
 |     blackhole_detector_.StopDetection(); | 
 |   } | 
 |   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"; | 
 |     DCHECK_LT(0u, sent_packet_manager_.pending_timer_transmission_count()); | 
 |     visitor_->SendPing(); | 
 |   } | 
 |   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(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) { | 
 |   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; | 
 |   if (level != encryption_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); | 
 | } | 
 |  | 
 | 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) { | 
 |   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); | 
 | } | 
 |  | 
 | 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); | 
 | } | 
 |  | 
 | void QuicConnection::MaybeProcessUndecryptablePackets() { | 
 |   process_undecryptable_packets_alarm_->Cancel(); | 
 |  | 
 |   if (undecryptable_packets_.empty() || | 
 |       encryption_level_ == ENCRYPTION_INITIAL) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (GetQuicReloadableFlag(quic_fix_undecryptable_packets)) { | 
 |     QUIC_RELOADABLE_FLAG_COUNT(quic_fix_undecryptable_packets); | 
 |     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; | 
 |       ++iter; | 
 |       if (undecryptable_packet->processed) { | 
 |         continue; | 
 |       } | 
 |       QUIC_DVLOG(1) << ENDPOINT << "Attempting to process undecryptable packet"; | 
 |       if (debug_visitor_ != nullptr) { | 
 |         debug_visitor_->OnAttemptingToProcessUndecryptablePacket( | 
 |             undecryptable_packet->encryption_level); | 
 |       } | 
 |       if (framer_.ProcessPacket(*undecryptable_packet->packet)) { | 
 |         QUIC_DVLOG(1) << ENDPOINT << "Processed undecryptable packet!"; | 
 |         undecryptable_packet->processed = true; | 
 |         ++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"; | 
 |         continue; | 
 |       } | 
 |       undecryptable_packet->processed = true; | 
 |     } | 
 |     // Remove processed packets. We cannot remove elements in the while loop | 
 |     // above because currently QuicCircularDeque does not support removing | 
 |     // mid elements. | 
 |     while (!undecryptable_packets_.empty()) { | 
 |       if (!undecryptable_packets_.front().processed) { | 
 |         break; | 
 |       } | 
 |       undecryptable_packets_.pop_front(); | 
 |     } | 
 |   } else { | 
 |     while (connected_ && !undecryptable_packets_.empty()) { | 
 |       // 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; | 
 |       } | 
 |       QUIC_DVLOG(1) << ENDPOINT << "Attempting to process undecryptable packet"; | 
 |       const auto& undecryptable_packet = undecryptable_packets_.front(); | 
 |       if (debug_visitor_ != nullptr) { | 
 |         debug_visitor_->OnAttemptingToProcessUndecryptablePacket( | 
 |             undecryptable_packet.encryption_level); | 
 |       } | 
 |       if (!framer_.ProcessPacket(*undecryptable_packet.packet) && | 
 |           framer_.error() == QUIC_DECRYPTION_FAILURE) { | 
 |         QUIC_DVLOG(1) << ENDPOINT | 
 |                       << "Unable to process undecryptable packet..."; | 
 |         break; | 
 |       } | 
 |       QUIC_DVLOG(1) << ENDPOINT << "Processed undecryptable packet!"; | 
 |       ++stats_.packets_processed; | 
 |       undecryptable_packets_.pop_front(); | 
 |     } | 
 |   } | 
 |  | 
 |   // Once forward secure encryption is in use, there will be no | 
 |   // new keys installed and hence any undecryptable packets will | 
 |   // never be able to be decrypted. | 
 |   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE) { | 
 |     if (debug_visitor_ != nullptr) { | 
 |       for (const auto& undecryptable_packet : undecryptable_packets_) { | 
 |         debug_visitor_->OnUndecryptablePacket( | 
 |             undecryptable_packet.encryption_level, /*dropped=*/true); | 
 |       } | 
 |     } | 
 |     undecryptable_packets_.clear(); | 
 |   } | 
 | } | 
 |  | 
 | 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; | 
 | } | 
 |  | 
 | void 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; | 
 |     } | 
 |  | 
 |     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(); | 
 |   } | 
 | } | 
 |  | 
 | void QuicConnection::CloseConnection( | 
 |     QuicErrorCode error, | 
 |     const std::string& error_details, | 
 |     ConnectionCloseBehavior connection_close_behavior) { | 
 |   DCHECK(!error_details.empty()); | 
 |   if (!connected_) { | 
 |     QUIC_DLOG(INFO) << "Connection is already closed."; | 
 |     return; | 
 |   } | 
 |  | 
 |   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, error_details); | 
 |   } | 
 |  | 
 |   TearDownLocalConnectionState(error, error_details, | 
 |                                ConnectionCloseSource::FROM_SELF); | 
 | } | 
 |  | 
 | void QuicConnection::SendConnectionClosePacket(QuicErrorCode error, | 
 |                                                const std::string& details) { | 
 |   if (!SupportsMultiplePacketNumberSpaces()) { | 
 |     QUIC_DLOG(INFO) << ENDPOINT << "Sending connection close packet."; | 
 |     SetDefaultEncryptionLevel(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. | 
 |     if (error != QUIC_PACKET_WRITE_ERROR && | 
 |         !uber_received_packet_manager_.IsAckFrameEmpty( | 
 |             QuicUtils::GetPacketNumberSpace(encryption_level_))) { | 
 |       SendAck(); | 
 |     } | 
 |     QuicConnectionCloseFrame* frame; | 
 |  | 
 |     frame = new QuicConnectionCloseFrame(transport_version(), error, details, | 
 |                                          framer_.current_received_frame_type()); | 
 |     packet_creator_.ConsumeRetransmittableControlFrame(QuicFrame(frame)); | 
 |     packet_creator_.FlushCurrentPacket(); | 
 |     if (version().CanSendCoalescedPackets()) { | 
 |       FlushCoalescedPacket(); | 
 |     } | 
 |     ClearQueuedPackets(); | 
 |     return; | 
 |   } | 
 |   const EncryptionLevel current_encryption_level = encryption_level_; | 
 |   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; | 
 |     SetDefaultEncryptionLevel(level); | 
 |     // Bundle an ACK of the corresponding packet number space for debugging | 
 |     // purpose. | 
 |     if (error != QUIC_PACKET_WRITE_ERROR && | 
 |         !uber_received_packet_manager_.IsAckFrameEmpty( | 
 |             QuicUtils::GetPacketNumberSpace(encryption_level_))) { | 
 |       QuicFrames frames; | 
 |       frames.push_back(GetUpdatedAckFrame()); | 
 |       packet_creator_.FlushAckFrame(frames); | 
 |     } | 
 |  | 
 |     auto* frame = | 
 |         new QuicConnectionCloseFrame(transport_version(), 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(); | 
 |   SetDefaultEncryptionLevel(current_encryption_level); | 
 | } | 
 |  | 
 | void QuicConnection::TearDownLocalConnectionState( | 
 |     QuicErrorCode error, | 
 |     const std::string& error_details, | 
 |     ConnectionCloseSource source) { | 
 |   QuicConnectionCloseFrame frame(transport_version(), 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; | 
 |   DCHECK(visitor_ != nullptr); | 
 |   sent_packet_manager_.OnConnectionClosed(); | 
 |   visitor_->OnConnectionClosed(frame, source); | 
 |   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(); | 
 | } | 
 |  | 
 | void QuicConnection::CancelAllAlarms() { | 
 |   QUIC_DVLOG(1) << "Cancelling all QuicConnection alarms."; | 
 |  | 
 |   ack_alarm_->Cancel(); | 
 |   ping_alarm_->Cancel(); | 
 |   retransmission_alarm_->Cancel(); | 
 |   send_alarm_->Cancel(); | 
 |   mtu_discovery_alarm_->Cancel(); | 
 |   process_undecryptable_packets_alarm_->Cancel(); | 
 |   blackhole_detector_.StopDetection(); | 
 |   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; | 
 |   MaybeUpdatePacketCreatorMaxPacketLengthAndPadding(); | 
 | } | 
 |  | 
 | bool QuicConnection::HasQueuedData() const { | 
 |   return pending_version_negotiation_packet_ || | 
 |          packet_creator_.HasPendingFrames() || !buffered_packets_.empty(); | 
 | } | 
 |  | 
 | void QuicConnection::SetNetworkTimeouts(QuicTime::Delta handshake_timeout, | 
 |                                         QuicTime::Delta idle_timeout) { | 
 |   QUIC_BUG_IF(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 (perspective_ == Perspective::IS_SERVER) { | 
 |     // Only clients send pings to avoid NATs from timing out. | 
 |     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()) { | 
 |     // Extend the ping alarm. | 
 |     ping_alarm_->Update(clock_->ApproximateNow() + ping_timeout_, | 
 |                         QuicTime::Delta::FromSeconds(1)); | 
 |     return; | 
 |   } | 
 |   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); | 
 |   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_++; | 
 |     } | 
 |     return; | 
 |   } | 
 |  | 
 |   ping_alarm_->Update(clock_->ApproximateNow() + ping_timeout_, | 
 |                       kAlarmGranularity); | 
 | } | 
 |  | 
 | void QuicConnection::SetRetransmissionAlarm() { | 
 |   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(sent_packet_manager_.GetRetransmissionTime(), | 
 |                                 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) { | 
 |   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_->FlushCoalescedPacket(); | 
 |     } | 
 |     connection_->FlushPackets(); | 
 |     // 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; | 
 |     } | 
 |   } | 
 |   DCHECK_EQ(flush_and_set_pending_retransmission_alarm_on_delete_, | 
 |             !connection_->packet_creator_.PacketFlusherAttached()); | 
 | } | 
 |  | 
 | 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) { | 
 |   if (packet.retransmittable_frames.empty()) { | 
 |     return false; | 
 |   } | 
 |   for (const QuicFrame& frame : packet.retransmittable_frames) { | 
 |     if (frame.type == CONNECTION_CLOSE_FRAME) { | 
 |       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 << "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. | 
 |   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) { | 
 |   DCHECK(peer_address.IsInitialized()); | 
 |   if (!connected_) { | 
 |     QUIC_BUG << "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_; | 
 |   } | 
 |   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 = " | 
 |                   << 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) { | 
 |     // 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>(); | 
 |     probing_packet = | 
 |         packet_creator_.SerializePathChallengeConnectivityProbingPacket( | 
 |             transmitted_connectivity_probe_payload_.get()); | 
 |     if (!probing_packet) { | 
 |       transmitted_connectivity_probe_payload_ = nullptr; | 
 |     } | 
 |   } | 
 |  | 
 |   DCHECK_EQ(IsRetransmittable(*probing_packet), NO_RETRANSMITTABLE_DATA); | 
 |  | 
 |   const QuicTime packet_send_time = clock_->Now(); | 
 |   QUIC_DVLOG(2) << ENDPOINT | 
 |                 << "Sending path probe packet for server connection ID " | 
 |                 << server_connection_id_ << std::endl | 
 |                 << quiche::QuicheTextUtils::HexDump(quiche::QuicheStringPiece( | 
 |                        probing_packet->encrypted_buffer, | 
 |                        probing_packet->encrypted_length)); | 
 |   WriteResult result = probing_writer->WritePacket( | 
 |       probing_packet->encrypted_buffer, probing_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 (probing_writer->IsBatchMode() && result.status == WRITE_STATUS_OK && | 
 |       result.bytes_written == 0) { | 
 |     result = probing_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; | 
 |   } | 
 |  | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnPacketSent( | 
 |         *probing_packet, probing_packet->transmission_type, packet_send_time); | 
 |   } | 
 |  | 
 |   // Call OnPacketSent regardless of the write result. | 
 |   sent_packet_manager_.OnPacketSent(probing_packet.get(), packet_send_time, | 
 |                                     probing_packet->transmission_type, | 
 |                                     NO_RETRANSMITTABLE_DATA); | 
 |  | 
 |   if (IsWriteBlockedStatus(result.status)) { | 
 |     if (probing_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::DiscoverMtu() { | 
 |   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)); | 
 |   } | 
 |   DCHECK(!mtu_discovery_alarm_->IsSet()); | 
 | } | 
 |  | 
 | void QuicConnection::OnEffectivePeerMigrationValidated() { | 
 |   if (active_effective_peer_migration_type_ == NO_CHANGE) { | 
 |     QUIC_BUG << "No migration underway."; | 
 |     return; | 
 |   } | 
 |   highest_packet_sent_before_effective_peer_migration_.Clear(); | 
 |   active_effective_peer_migration_type_ = NO_CHANGE; | 
 | } | 
 |  | 
 | 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 (type == NO_CHANGE) { | 
 |     QUIC_BUG << "EffectivePeerMigration started without address change."; | 
 |     return; | 
 |   } | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "Effective peer's ip:port changed from " | 
 |                   << effective_peer_address_.ToString() << " to " | 
 |                   << GetEffectivePeerAddressFromCurrentPacket().ToString() | 
 |                   << ", address change type is " << type | 
 |                   << ", migrating connection."; | 
 |  | 
 |   highest_packet_sent_before_effective_peer_migration_ = | 
 |       sent_packet_manager_.GetLargestSentPacket(); | 
 |   effective_peer_address_ = GetEffectivePeerAddressFromCurrentPacket(); | 
 |   active_effective_peer_migration_type_ = type; | 
 |  | 
 |   // TODO(wub): Move these calls to OnEffectivePeerMigrationValidated. | 
 |   OnConnectionMigration(type); | 
 | } | 
 |  | 
 | void QuicConnection::OnConnectionMigration(AddressChangeType addr_change_type) { | 
 |   visitor_->OnConnectionMigration(addr_change_type); | 
 |   sent_packet_manager_.OnConnectionMigration(addr_change_type); | 
 | } | 
 |  | 
 | bool QuicConnection::IsCurrentPacketConnectivityProbing() const { | 
 |   return is_current_packet_connectivity_probing_; | 
 | } | 
 |  | 
 | bool QuicConnection::ack_frame_updated() const { | 
 |   return uber_received_packet_manager_.IsAckFrameUpdated(); | 
 | } | 
 |  | 
 | quiche::QuicheStringPiece QuicConnection::GetCurrentPacket() { | 
 |   if (current_packet_data_ == nullptr) { | 
 |     return quiche::QuicheStringPiece(); | 
 |   } | 
 |   return quiche::QuicheStringPiece(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() { | 
 |   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 << "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 (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(); | 
 | } | 
 |  | 
 | void QuicConnection::UpdatePacketContent(PacketContent type) { | 
 |   // 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 (version().HasIetfQuicFrames()) { | 
 |     return; | 
 |   } | 
 |  | 
 |   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; | 
 |   } | 
 |  | 
 |   if (type == NO_FRAMES_RECEIVED) { | 
 |     return; | 
 |   } | 
 |  | 
 |   if (type == FIRST_FRAME_IS_PING) { | 
 |     if (current_packet_content_ == NO_FRAMES_RECEIVED) { | 
 |       current_packet_content_ = FIRST_FRAME_IS_PING; | 
 |       return; | 
 |     } | 
 |   } | 
 |  | 
 |   // 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 == SECOND_FRAME_IS_PADDING && | 
 |       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_packet_source_address_ != peer_address_) || | 
 |           (last_packet_destination_address_ != self_address_); | 
 |       QUIC_DLOG_IF(INFO, is_current_packet_connectivity_probing_) | 
 |           << ENDPOINT | 
 |           << "Detected connectivity probing packet. " | 
 |              "last_packet_source_address_:" | 
 |           << last_packet_source_address_ << ", peer_address_:" << peer_address_ | 
 |           << ", last_packet_destination_address_:" | 
 |           << last_packet_destination_address_ | 
 |           << ", self_address_:" << self_address_; | 
 |     } | 
 |     return; | 
 |   } | 
 |  | 
 |   current_packet_content_ = NOT_PADDED_PING; | 
 |   if (GetLargestReceivedPacket().IsInitialized() && | 
 |       last_header_.packet_number == GetLargestReceivedPacket()) { | 
 |     direct_peer_address_ = last_packet_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. | 
 |       // TODO(fayang): When multiple packet number spaces is supported, only | 
 |       // start peer migration for the application data. | 
 |       StartEffectivePeerMigration(current_effective_peer_migration_type_); | 
 |     } | 
 |   } | 
 |   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(); | 
 |   } | 
 |  | 
 |   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() { | 
 |   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, | 
 |                                           QuicMemSliceSpan message, | 
 |                                           bool flush) { | 
 |   if (!VersionSupportsMessageFrames(transport_version())) { | 
 |     QUIC_BUG << "MESSAGE frame is not supported for version " | 
 |              << transport_version(); | 
 |     return MESSAGE_STATUS_UNSUPPORTED; | 
 |   } | 
 |   if (message.total_length() > 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(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 (VersionHasIetfInvariantHeader(transport_version())) { | 
 |         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::MaybeBundleCryptoDataWithAckOfSpace( | 
 |     PacketNumberSpace space) { | 
 |   DCHECK(SupportsMultiplePacketNumberSpaces()); | 
 |   QUIC_BUG_IF(space == APPLICATION_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; | 
 |   } | 
 |  | 
 |   sent_packet_manager_.RetransmitDataOfSpaceIfAny(space); | 
 | } | 
 |  | 
 | void QuicConnection::SendAllPendingAcks() { | 
 |   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(!earliest_ack_timeout.IsInitialized()); | 
 |   if (GetQuicReloadableFlag(quic_bundle_crypto_data_with_initial_ack)) { | 
 |     // On the server side, sends INITIAL data with INITIAL ACK. On the client | 
 |     // side, sends HANDSHAKE data (containing client Finished) with HANDSHAKE | 
 |     // ACK. | 
 |     PacketNumberSpace space = | 
 |         perspective() == Perspective::IS_SERVER ? INITIAL_DATA : HANDSHAKE_DATA; | 
 |     MaybeBundleCryptoDataWithAckOfSpace(space); | 
 |     earliest_ack_timeout = | 
 |         uber_received_packet_manager_.GetEarliestAckTimeout(); | 
 |     if (!earliest_ack_timeout.IsInitialized()) { | 
 |       QUIC_RELOADABLE_FLAG_COUNT(quic_bundle_crypto_data_with_initial_ack); | 
 |       return; | 
 |     } | 
 |   } | 
 |   // Latches current encryption level. | 
 |   const EncryptionLevel current_encryption_level = encryption_level_; | 
 |   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 (GetQuicReloadableFlag(quic_always_send_earliest_ack)) { | 
 |       QUIC_RELOADABLE_FLAG_COUNT(quic_always_send_earliest_ack); | 
 |     } | 
 |     if (ack_timeout > clock_->ApproximateNow()) { | 
 |       if (!GetQuicReloadableFlag(quic_always_send_earliest_ack)) { | 
 |         continue; | 
 |       } | 
 |       if (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)); | 
 |     // Switch to the appropriate encryption level. | 
 |     SetDefaultEncryptionLevel( | 
 |         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( | 
 |           !writer_->IsWriteBlocked() && | 
 |           (!move_amplification_limit_ || !LimitedByAmplificationFactor())) | 
 |           << "Writer not blocked and not throttled by amplification factor, " | 
 |              "but ACK not flushed for packet space:" | 
 |           << i; | 
 |       break; | 
 |     } | 
 |     ResetAckStates(); | 
 |   } | 
 |   // Restores encryption level. | 
 |   SetDefaultEncryptionLevel(current_encryption_level); | 
 |  | 
 |   const QuicTime timeout = | 
 |       uber_received_packet_manager_.GetEarliestAckTimeout(); | 
 |   if (timeout.IsInitialized()) { | 
 |     // If there are ACKs pending, re-arm ack alarm. | 
 |     if (update_ack_alarm_in_send_all_pending_acks_) { | 
 |       QUIC_RELOADABLE_FLAG_COUNT( | 
 |           quic_update_ack_alarm_in_send_all_pending_acks); | 
 |       ack_alarm_->Update(timeout, kAlarmGranularity); | 
 |     } else { | 
 |       ack_alarm_->Set(timeout); | 
 |     } | 
 |   } | 
 |   // 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; | 
 | } | 
 |  | 
 | bool QuicConnection::FlushCoalescedPacket() { | 
 |   ScopedCoalescedPacketClearer clearer(&coalesced_packet_); | 
 |   if (!version().CanSendCoalescedPackets()) { | 
 |     QUIC_BUG_IF(coalesced_packet_.length() > 0); | 
 |     return true; | 
 |   } | 
 |   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; | 
 |   } | 
 |   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, length, | 
 |                                    coalesced_packet_.self_address(), | 
 |                                    coalesced_packet_.peer_address()); | 
 |     if (debug_visitor_ != nullptr) { | 
 |       debug_visitor_->OnCoalescedPacketSent(coalesced_packet_, length); | 
 |     } | 
 |     if (coalesced_packet_.ContainsPacketOfEncryptionLevel( | 
 |             ENCRYPTION_HANDSHAKE)) { | 
 |       // This is only called in coalescer because all ENCRYPTION_HANDSHAKE | 
 |       // packets go through the coalescer. | 
 |       visitor_->OnHandshakePacketSent(); | 
 |     } | 
 |     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, length, | 
 |                                      coalesced_packet_.self_address(), | 
 |                                      coalesced_packet_.peer_address()); | 
 |     } | 
 |   } | 
 |   if (debug_visitor_ != nullptr) { | 
 |     debug_visitor_->OnCoalescedPacketSent(coalesced_packet_, length); | 
 |   } | 
 |   if (coalesced_packet_.ContainsPacketOfEncryptionLevel(ENCRYPTION_HANDSHAKE)) { | 
 |     // This is only called in coalescer because all ENCRYPTION_HANDSHAKE | 
 |     // packets go through the coalescer. | 
 |     visitor_->OnHandshakePacketSent(); | 
 |   } | 
 |   // Account for added padding. | 
 |   if (length > coalesced_packet_.length()) { | 
 |     size_t padding_size = length - coalesced_packet_.length(); | 
 |     if (EnforceAntiAmplificationLimit()) { | 
 |       bytes_sent_before_address_validation_ += 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(); | 
 | } | 
 |  | 
 | 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 (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()); | 
 |   } else { | 
 |     // Stop detections in quiecense. | 
 |     blackhole_detector_.StopDetection(); | 
 |   } | 
 |   QUIC_BUG_IF(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 && !address_validated_; | 
 | } | 
 |  | 
 | bool QuicConnection::LimitedByAmplificationFactor() const { | 
 |   return EnforceAntiAmplificationLimit() && | 
 |          bytes_sent_before_address_validation_ >= | 
 |              anti_amplification_factor_ * | 
 |                  bytes_received_before_address_validation_; | 
 | } | 
 |  | 
 | SerializedPacketFate QuicConnection::GetSerializedPacketFate( | 
 |     bool is_mtu_discovery, | 
 |     EncryptionLevel encryption_level) { | 
 |   if (packet_creator_.determine_serialized_packet_fate_early()) { | 
 |     if (ShouldDiscardPacket(encryption_level)) { | 
 |       return DISCARD; | 
 |     } | 
 |   } | 
 |   if (legacy_version_encapsulation_in_progress_) { | 
 |     DCHECK(!is_mtu_discovery); | 
 |     return LEGACY_VERSION_ENCAPSULATE; | 
 |   } | 
 |   if (version().CanSendCoalescedPackets()) { | 
 |     // Disable coalescing when Legacy Version Encapsulation is in use to avoid | 
 |     // having to reframe encapsulated packets. | 
 |     if (!IsHandshakeConfirmed() && !is_mtu_discovery) { | 
 |       // Before receiving ACK for any 1-RTT packets, always try to coalesce | 
 |       // packet (except MTU discovery packet). | 
 |       return COALESCE; | 
 |     } | 
 |     // Packet cannot be coalesced, flush existing coalesced packet. | 
 |     if (!packet_creator_.determine_serialized_packet_fate_early() && | 
 |         !FlushCoalescedPacket()) { | 
 |       return FAILED_TO_WRITE_COALESCED_PACKET; | 
 |     } | 
 |   } | 
 |   if (!buffered_packets_.empty() || HandleWriteBlocked()) { | 
 |     return BUFFER; | 
 |   } | 
 |   return SEND_TO_WRITER; | 
 | } | 
 |  | 
 | bool QuicConnection::IsHandshakeComplete() const { | 
 |   return visitor_->GetHandshakeState() >= HANDSHAKE_COMPLETE; | 
 | } | 
 |  | 
 | bool QuicConnection::IsHandshakeConfirmed() const { | 
 |   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); | 
 | } | 
 |  | 
 | size_t QuicConnection::ack_frequency_before_ack_decimation() const { | 
 |   return uber_received_packet_manager_.ack_frequency_before_ack_decimation(); | 
 | } | 
 |  | 
 | void QuicConnection::set_ack_frequency_before_ack_decimation(size_t new_value) { | 
 |   DCHECK_GT(new_value, 0u); | 
 |   uber_received_packet_manager_.set_ack_frequency_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(!client_connection_id.IsEmpty()) | 
 |         << ENDPOINT << "Attempted to use client connection ID " | 
 |         << client_connection_id << " with unsupported version " << version(); | 
 |     return; | 
 |   } | 
 |   client_connection_id_ = client_connection_id; | 
 |   client_connection_id_is_set_ = true; | 
 |   QUIC_DLOG(INFO) << ENDPOINT << "setting client connection ID to " | 
 |                   << client_connection_id_ | 
 |                   << " for connection with server connection ID " | 
 |                   << server_connection_id_; | 
 |   packet_creator_.SetClientConnectionId(client_connection_id_); | 
 |   framer_.SetExpectedClientConnectionIdLength(client_connection_id_.length()); | 
 | } | 
 |  | 
 | void QuicConnection::OnPathDegradingDetected() { | 
 |   is_path_degrading_ = true; | 
 |   visitor_->OnPathDegrading(); | 
 | } | 
 |  | 
 | void QuicConnection::OnBlackholeDetected() { | 
 |   QUIC_BUG_IF(default_enable_5rto_blackhole_detection_ && | 
 |               !sent_packet_manager_.HasInFlightPackets()) | 
 |       << ENDPOINT | 
 |       << "Closing connection because of blackhole, but there is no bytes in " | 
 |          "flight"; | 
 |   const std::string error_detail = quiche::QuicheStrCat( | 
 |       "Network blackhole detected", sent_packet_manager_.HasInFlightPackets() | 
 |                                         ? "." | 
 |                                         : " with no packets in flight."); | 
 |   CloseConnection(QUIC_TOO_MANY_RTOS, error_detail, | 
 |                   ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 | } | 
 |  | 
 | void QuicConnection::OnHandshakeTimeout() { | 
 |   const QuicTime::Delta duration = | 
 |       clock_->ApproximateNow() - stats_.connection_creation_time; | 
 |   std::string error_details = quiche::QuicheStrCat( | 
 |       "Handshake timeout expired after ", duration.ToDebuggingValue(), | 
 |       ". Timeout:", | 
 |       idle_network_detector_.handshake_timeout().ToDebuggingValue()); | 
 |   if (perspective() == Perspective::IS_CLIENT && version().UsesTls()) { | 
 |     error_details = | 
 |         quiche::QuicheStrCat(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(); | 
 |   const std::string error_details = quiche::QuicheStrCat( | 
 |       "No recent network activity after ", duration.ToDebuggingValue(), | 
 |       ". Timeout:", | 
 |       idle_network_detector_.idle_network_timeout().ToDebuggingValue()); | 
 |   QUIC_DVLOG(1) << ENDPOINT << error_details; | 
 |   if ((sent_packet_manager_.GetConsecutiveTlpCount() > 0 || | 
 |        sent_packet_manager_.GetConsecutiveRtoCount() > 0 || | 
 |        sent_packet_manager_.GetConsecutivePtoCount() > 0 || | 
 |        visitor_->ShouldKeepConnectionAlive())) { | 
 |     CloseConnection(QUIC_NETWORK_IDLE_TIMEOUT, error_details, | 
 |                     ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET); | 
 |     return; | 
 |   } | 
 |   CloseConnection(QUIC_NETWORK_IDLE_TIMEOUT, error_details, | 
 |                   idle_timeout_connection_close_behavior_); | 
 | } | 
 |  | 
 | 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, | 
 |       idle_network_detector_.time_of_last_received_packet(), | 
 |       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(); | 
 |   } | 
 |   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; | 
 | } | 
 |  | 
 | #undef ENDPOINT  // undef for jumbo builds | 
 | }  // namespace quic |