quic/core/quic_connection_test.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "quic/core/quic_connection.h"

#include <errno.h>

#include <memory>
#include <ostream>
#include <string>
#include <utility>

#include "absl/base/macros.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"
#include "quic/core/congestion_control/loss_detection_interface.h"
#include "quic/core/congestion_control/send_algorithm_interface.h"
#include "quic/core/crypto/null_decrypter.h"
#include "quic/core/crypto/null_encrypter.h"
#include "quic/core/crypto/quic_decrypter.h"
#include "quic/core/crypto/quic_encrypter.h"
#include "quic/core/frames/quic_connection_close_frame.h"
#include "quic/core/frames/quic_new_connection_id_frame.h"
#include "quic/core/frames/quic_path_response_frame.h"
#include "quic/core/frames/quic_rst_stream_frame.h"
#include "quic/core/quic_connection_id.h"
#include "quic/core/quic_constants.h"
#include "quic/core/quic_error_codes.h"
#include "quic/core/quic_packet_creator.h"
#include "quic/core/quic_packets.h"
#include "quic/core/quic_path_validator.h"
#include "quic/core/quic_simple_buffer_allocator.h"
#include "quic/core/quic_types.h"
#include "quic/core/quic_utils.h"
#include "quic/core/quic_versions.h"
#include "quic/platform/api/quic_error_code_wrappers.h"
#include "quic/platform/api/quic_expect_bug.h"
#include "quic/platform/api/quic_flags.h"
#include "quic/platform/api/quic_ip_address.h"
#include "quic/platform/api/quic_logging.h"
#include "quic/platform/api/quic_reference_counted.h"
#include "quic/platform/api/quic_socket_address.h"
#include "quic/platform/api/quic_test.h"
#include "quic/test_tools/mock_clock.h"
#include "quic/test_tools/mock_random.h"
#include "quic/test_tools/quic_config_peer.h"
#include "quic/test_tools/quic_connection_peer.h"
#include "quic/test_tools/quic_framer_peer.h"
#include "quic/test_tools/quic_packet_creator_peer.h"
#include "quic/test_tools/quic_path_validator_peer.h"
#include "quic/test_tools/quic_sent_packet_manager_peer.h"
#include "quic/test_tools/quic_test_utils.h"
#include "quic/test_tools/simple_data_producer.h"
#include "quic/test_tools/simple_session_notifier.h"

using testing::_;
using testing::AnyNumber;
using testing::AtLeast;
using testing::DoAll;
using testing::ElementsAre;
using testing::Ge;
using testing::IgnoreResult;
using testing::InSequence;
using testing::Invoke;
using testing::InvokeWithoutArgs;
using testing::Lt;
using testing::Ref;
using testing::Return;
using testing::SaveArg;
using testing::SetArgPointee;
using testing::StrictMock;

namespace quic {
namespace test {
namespace {

const char data1[] = "foo data";
const char data2[] = "bar data";

const bool kHasStopWaiting = true;

const int kDefaultRetransmissionTimeMs = 500;

DiversificationNonce kTestDiversificationNonce = {
    'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a',
    'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b',
    'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b',
};

const StatelessResetToken kTestStatelessResetToken{
    0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,
    0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f};

const QuicSocketAddress kPeerAddress =
    QuicSocketAddress(QuicIpAddress::Loopback6(),
                      /*port=*/12345);
const QuicSocketAddress kSelfAddress =
    QuicSocketAddress(QuicIpAddress::Loopback6(),
                      /*port=*/443);

QuicStreamId GetNthClientInitiatedStreamId(int n,
                                           QuicTransportVersion version) {
  return QuicUtils::GetFirstBidirectionalStreamId(version,
                                                  Perspective::IS_CLIENT) +
         n * 2;
}

QuicLongHeaderType EncryptionlevelToLongHeaderType(EncryptionLevel level) {
  switch (level) {
    case ENCRYPTION_INITIAL:
      return INITIAL;
    case ENCRYPTION_HANDSHAKE:
      return HANDSHAKE;
    case ENCRYPTION_ZERO_RTT:
      return ZERO_RTT_PROTECTED;
    case ENCRYPTION_FORWARD_SECURE:
      QUICHE_DCHECK(false);
      return INVALID_PACKET_TYPE;
    default:
      QUICHE_DCHECK(false);
      return INVALID_PACKET_TYPE;
  }
}

// A NullEncrypterWithConfidentialityLimit is a NullEncrypter that allows
// specifying the confidentiality limit on the maximum number of packets that
// may be encrypted per key phase in TLS+QUIC.
class NullEncrypterWithConfidentialityLimit : public NullEncrypter {
 public:
  NullEncrypterWithConfidentialityLimit(Perspective perspective,
                                        QuicPacketCount confidentiality_limit)
      : NullEncrypter(perspective),
        confidentiality_limit_(confidentiality_limit) {}

  QuicPacketCount GetConfidentialityLimit() const override {
    return confidentiality_limit_;
  }

 private:
  QuicPacketCount confidentiality_limit_;
};

class StrictTaggingDecrypterWithIntegrityLimit : public StrictTaggingDecrypter {
 public:
  StrictTaggingDecrypterWithIntegrityLimit(uint8_t tag,
                                           QuicPacketCount integrity_limit)
      : StrictTaggingDecrypter(tag), integrity_limit_(integrity_limit) {}

  QuicPacketCount GetIntegrityLimit() const override {
    return integrity_limit_;
  }

 private:
  QuicPacketCount integrity_limit_;
};

class TestConnectionHelper : public QuicConnectionHelperInterface {
 public:
  TestConnectionHelper(MockClock* clock, MockRandom* random_generator)
      : clock_(clock), random_generator_(random_generator) {
    clock_->AdvanceTime(QuicTime::Delta::FromSeconds(1));
  }
  TestConnectionHelper(const TestConnectionHelper&) = delete;
  TestConnectionHelper& operator=(const TestConnectionHelper&) = delete;

  // QuicConnectionHelperInterface
  const QuicClock* GetClock() const override { return clock_; }

  QuicRandom* GetRandomGenerator() override { return random_generator_; }

  QuicBufferAllocator* GetStreamSendBufferAllocator() override {
    return &buffer_allocator_;
  }

 private:
  MockClock* clock_;
  MockRandom* random_generator_;
  SimpleBufferAllocator buffer_allocator_;
};

class TestConnection : public QuicConnection {
 public:
  TestConnection(QuicConnectionId connection_id,
                 QuicSocketAddress initial_self_address,
                 QuicSocketAddress initial_peer_address,
                 TestConnectionHelper* helper,
                 TestAlarmFactory* alarm_factory,
                 TestPacketWriter* writer,
                 Perspective perspective,
                 ParsedQuicVersion version)
      : QuicConnection(connection_id,
                       initial_self_address,
                       initial_peer_address,
                       helper,
                       alarm_factory,
                       writer,
                       /* owns_writer= */ false,
                       perspective,
                       SupportedVersions(version)),
        notifier_(nullptr) {
    writer->set_perspective(perspective);
    SetEncrypter(ENCRYPTION_FORWARD_SECURE,
                 std::make_unique<NullEncrypter>(perspective));
    SetDataProducer(&producer_);
  }
  TestConnection(const TestConnection&) = delete;
  TestConnection& operator=(const TestConnection&) = delete;

  void SetSendAlgorithm(SendAlgorithmInterface* send_algorithm) {
    QuicConnectionPeer::SetSendAlgorithm(this, send_algorithm);
  }

  void SetLossAlgorithm(LossDetectionInterface* loss_algorithm) {
    QuicConnectionPeer::SetLossAlgorithm(this, loss_algorithm);
  }

  void SendPacket(EncryptionLevel /*level*/,
                  uint64_t packet_number,
                  std::unique_ptr<QuicPacket> packet,
                  HasRetransmittableData retransmittable,
                  bool has_ack,
                  bool has_pending_frames) {
    ScopedPacketFlusher flusher(this);
    char buffer[kMaxOutgoingPacketSize];
    size_t encrypted_length =
        QuicConnectionPeer::GetFramer(this)->EncryptPayload(
            ENCRYPTION_INITIAL, QuicPacketNumber(packet_number), *packet,
            buffer, kMaxOutgoingPacketSize);
    SerializedPacket serialized_packet(
        QuicPacketNumber(packet_number), PACKET_4BYTE_PACKET_NUMBER, buffer,
        encrypted_length, has_ack, has_pending_frames);
    serialized_packet.peer_address = kPeerAddress;
    if (retransmittable == HAS_RETRANSMITTABLE_DATA) {
      serialized_packet.retransmittable_frames.push_back(
          QuicFrame(QuicPingFrame()));
    }
    OnSerializedPacket(std::move(serialized_packet));
  }

  QuicConsumedData SaveAndSendStreamData(QuicStreamId id,
                                         const struct iovec* iov,
                                         int iov_count,
                                         size_t total_length,
                                         QuicStreamOffset offset,
                                         StreamSendingState state) {
    ScopedPacketFlusher flusher(this);
    producer_.SaveStreamData(id, iov, iov_count, 0u, total_length);
    if (notifier_ != nullptr) {
      return notifier_->WriteOrBufferData(id, total_length, state);
    }
    return QuicConnection::SendStreamData(id, total_length, offset, state);
  }

  QuicConsumedData SendStreamDataWithString(QuicStreamId id,
                                            absl::string_view data,
                                            QuicStreamOffset offset,
                                            StreamSendingState state) {
    ScopedPacketFlusher flusher(this);
    if (!QuicUtils::IsCryptoStreamId(transport_version(), id) &&
        this->encryption_level() == ENCRYPTION_INITIAL) {
      this->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
      if (perspective() == Perspective::IS_CLIENT && !IsHandshakeComplete()) {
        OnHandshakeComplete();
      }
      if (version().SupportsAntiAmplificationLimit()) {
        QuicConnectionPeer::SetAddressValidated(this);
      }
    }
    struct iovec iov;
    MakeIOVector(data, &iov);
    return SaveAndSendStreamData(id, &iov, 1, data.length(), offset, state);
  }

  QuicConsumedData SendApplicationDataAtLevel(EncryptionLevel encryption_level,
                                              QuicStreamId id,
                                              absl::string_view data,
                                              QuicStreamOffset offset,
                                              StreamSendingState state) {
    ScopedPacketFlusher flusher(this);
    QUICHE_DCHECK(encryption_level >= ENCRYPTION_ZERO_RTT);
    SetEncrypter(encryption_level, std::make_unique<TaggingEncrypter>(0x01));
    SetDefaultEncryptionLevel(encryption_level);
    struct iovec iov;
    MakeIOVector(data, &iov);
    return SaveAndSendStreamData(id, &iov, 1, data.length(), offset, state);
  }

  QuicConsumedData SendStreamData3() {
    return SendStreamDataWithString(
        GetNthClientInitiatedStreamId(1, transport_version()), "food", 0,
        NO_FIN);
  }

  QuicConsumedData SendStreamData5() {
    return SendStreamDataWithString(
        GetNthClientInitiatedStreamId(2, transport_version()), "food2", 0,
        NO_FIN);
  }

  // Ensures the connection can write stream data before writing.
  QuicConsumedData EnsureWritableAndSendStreamData5() {
    EXPECT_TRUE(CanWrite(HAS_RETRANSMITTABLE_DATA));
    return SendStreamData5();
  }

  // The crypto stream has special semantics so that it is not blocked by a
  // congestion window limitation, and also so that it gets put into a separate
  // packet (so that it is easier to reason about a crypto frame not being
  // split needlessly across packet boundaries).  As a result, we have separate
  // tests for some cases for this stream.
  QuicConsumedData SendCryptoStreamData() {
    QuicStreamOffset offset = 0;
    absl::string_view data("chlo");
    if (!QuicVersionUsesCryptoFrames(transport_version())) {
      return SendCryptoDataWithString(data, offset);
    }
    producer_.SaveCryptoData(ENCRYPTION_INITIAL, offset, data);
    size_t bytes_written;
    if (notifier_) {
      bytes_written =
          notifier_->WriteCryptoData(ENCRYPTION_INITIAL, data.length(), offset);
    } else {
      bytes_written = QuicConnection::SendCryptoData(ENCRYPTION_INITIAL,
                                                     data.length(), offset);
    }
    return QuicConsumedData(bytes_written, /*fin_consumed*/ false);
  }

  QuicConsumedData SendCryptoDataWithString(absl::string_view data,
                                            QuicStreamOffset offset) {
    return SendCryptoDataWithString(data, offset, ENCRYPTION_INITIAL);
  }

  QuicConsumedData SendCryptoDataWithString(absl::string_view data,
                                            QuicStreamOffset offset,
                                            EncryptionLevel encryption_level) {
    if (!QuicVersionUsesCryptoFrames(transport_version())) {
      return SendStreamDataWithString(
          QuicUtils::GetCryptoStreamId(transport_version()), data, offset,
          NO_FIN);
    }
    producer_.SaveCryptoData(encryption_level, offset, data);
    size_t bytes_written;
    if (notifier_) {
      bytes_written =
          notifier_->WriteCryptoData(encryption_level, data.length(), offset);
    } else {
      bytes_written = QuicConnection::SendCryptoData(encryption_level,
                                                     data.length(), offset);
    }
    return QuicConsumedData(bytes_written, /*fin_consumed*/ false);
  }

  void set_version(ParsedQuicVersion version) {
    QuicConnectionPeer::GetFramer(this)->set_version(version);
  }

  void SetSupportedVersions(const ParsedQuicVersionVector& versions) {
    QuicConnectionPeer::GetFramer(this)->SetSupportedVersions(versions);
    writer()->SetSupportedVersions(versions);
  }

  // This should be called before setting customized encrypters/decrypters for
  // connection and peer creator.
  void set_perspective(Perspective perspective) {
    writer()->set_perspective(perspective);
    QuicConnectionPeer::ResetPeerIssuedConnectionIdManager(this);
    QuicConnectionPeer::SetPerspective(this, perspective);
    QuicSentPacketManagerPeer::SetPerspective(
        QuicConnectionPeer::GetSentPacketManager(this), perspective);
    QuicConnectionPeer::GetFramer(this)->SetInitialObfuscators(
        TestConnectionId());
    for (EncryptionLevel level : {ENCRYPTION_ZERO_RTT, ENCRYPTION_HANDSHAKE,
                                  ENCRYPTION_FORWARD_SECURE}) {
      if (QuicConnectionPeer::GetFramer(this)->HasEncrypterOfEncryptionLevel(
              level)) {
        SetEncrypter(level, std::make_unique<NullEncrypter>(perspective));
      }
      if (QuicConnectionPeer::GetFramer(this)->HasDecrypterOfEncryptionLevel(
              level)) {
        InstallDecrypter(level, std::make_unique<NullDecrypter>(perspective));
      }
    }
  }

  // Enable path MTU discovery.  Assumes that the test is performed from the
  // server perspective and the higher value of MTU target is used.
  void EnablePathMtuDiscovery(MockSendAlgorithm* send_algorithm) {
    ASSERT_EQ(Perspective::IS_SERVER, perspective());

    if (GetQuicReloadableFlag(quic_enable_mtu_discovery_at_server)) {
      OnConfigNegotiated();
    } else {
      QuicConfig config;
      QuicTagVector connection_options;
      connection_options.push_back(kMTUH);
      config.SetInitialReceivedConnectionOptions(connection_options);
      EXPECT_CALL(*send_algorithm, SetFromConfig(_, _));
      SetFromConfig(config);
    }

    // Normally, the pacing would be disabled in the test, but calling
    // SetFromConfig enables it.  Set nearly-infinite bandwidth to make the
    // pacing algorithm work.
    EXPECT_CALL(*send_algorithm, PacingRate(_))
        .WillRepeatedly(Return(QuicBandwidth::Infinite()));
  }

  TestAlarmFactory::TestAlarm* GetAckAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetAckAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetPingAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetPingAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetRetransmissionAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetRetransmissionAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetSendAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetSendAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetTimeoutAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetIdleNetworkDetectorAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetMtuDiscoveryAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetMtuDiscoveryAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetProcessUndecryptablePacketsAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetProcessUndecryptablePacketsAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetDiscardPreviousOneRttKeysAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetDiscardPreviousOneRttKeysAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetDiscardZeroRttDecryptionKeysAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetDiscardZeroRttDecryptionKeysAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetBlackholeDetectorAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetBlackholeDetectorAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetRetirePeerIssuedConnectionIdAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetRetirePeerIssuedConnectionIdAlarm(this));
  }

  TestAlarmFactory::TestAlarm* GetRetireSelfIssuedConnectionIdAlarm() {
    return reinterpret_cast<TestAlarmFactory::TestAlarm*>(
        QuicConnectionPeer::GetRetireSelfIssuedConnectionIdAlarm(this));
  }

  void PathDegradingTimeout() {
    QUICHE_DCHECK(PathDegradingDetectionInProgress());
    GetBlackholeDetectorAlarm()->Fire();
  }

  bool PathDegradingDetectionInProgress() {
    return QuicConnectionPeer::GetPathDegradingDeadline(this).IsInitialized();
  }

  bool BlackholeDetectionInProgress() {
    return QuicConnectionPeer::GetBlackholeDetectionDeadline(this)
        .IsInitialized();
  }

  bool PathMtuReductionDetectionInProgress() {
    return QuicConnectionPeer::GetPathMtuReductionDetectionDeadline(this)
        .IsInitialized();
  }

  void SetMaxTailLossProbes(size_t max_tail_loss_probes) {
    QuicSentPacketManagerPeer::SetMaxTailLossProbes(
        QuicConnectionPeer::GetSentPacketManager(this), max_tail_loss_probes);
  }

  QuicByteCount GetBytesInFlight() {
    return QuicConnectionPeer::GetSentPacketManager(this)->GetBytesInFlight();
  }

  void set_notifier(SimpleSessionNotifier* notifier) { notifier_ = notifier; }

  void ReturnEffectivePeerAddressForNextPacket(const QuicSocketAddress& addr) {
    next_effective_peer_addr_ = std::make_unique<QuicSocketAddress>(addr);
  }

  bool PtoEnabled() {
    if (QuicConnectionPeer::GetSentPacketManager(this)->pto_enabled()) {
      // PTO mode is default enabled for T099. And TLP/RTO related tests are
      // stale.
      QUICHE_DCHECK(PROTOCOL_TLS1_3 == version().handshake_protocol ||
                    GetQuicReloadableFlag(quic_default_on_pto));
      return true;
    }
    return false;
  }

  void SendOrQueuePacket(SerializedPacket packet) override {
    QuicConnection::SendOrQueuePacket(std::move(packet));
    self_address_on_default_path_while_sending_packet_ = self_address();
  }

  QuicSocketAddress self_address_on_default_path_while_sending_packet() {
    return self_address_on_default_path_while_sending_packet_;
  }

  SimpleDataProducer* producer() { return &producer_; }

  using QuicConnection::active_effective_peer_migration_type;
  using QuicConnection::IsCurrentPacketConnectivityProbing;
  using QuicConnection::SelectMutualVersion;
  using QuicConnection::SendProbingRetransmissions;
  using QuicConnection::set_defer_send_in_response_to_packets;

 protected:
  QuicSocketAddress GetEffectivePeerAddressFromCurrentPacket() const override {
    if (next_effective_peer_addr_) {
      return *std::move(next_effective_peer_addr_);
    }
    return QuicConnection::GetEffectivePeerAddressFromCurrentPacket();
  }

 private:
  TestPacketWriter* writer() {
    return static_cast<TestPacketWriter*>(QuicConnection::writer());
  }

  SimpleDataProducer producer_;

  SimpleSessionNotifier* notifier_;

  std::unique_ptr<QuicSocketAddress> next_effective_peer_addr_;

  QuicSocketAddress self_address_on_default_path_while_sending_packet_;
};

enum class AckResponse { kDefer, kImmediate };

// Run tests with combinations of {ParsedQuicVersion, AckResponse}.
struct TestParams {
  TestParams(ParsedQuicVersion version,
             AckResponse ack_response,
             bool no_stop_waiting)
      : version(version),
        ack_response(ack_response),
        no_stop_waiting(no_stop_waiting) {}

  ParsedQuicVersion version;
  AckResponse ack_response;
  bool no_stop_waiting;
};

// Used by ::testing::PrintToStringParamName().
std::string PrintToString(const TestParams& p) {
  return absl::StrCat(
      ParsedQuicVersionToString(p.version), "_",
      (p.ack_response == AckResponse::kDefer ? "defer" : "immediate"), "_",
      (p.no_stop_waiting ? "No" : ""), "StopWaiting");
}

// Constructs various test permutations.
std::vector<TestParams> GetTestParams() {
  QuicFlagSaver flags;
  std::vector<TestParams> params;
  ParsedQuicVersionVector all_supported_versions = AllSupportedVersions();
  for (size_t i = 0; i < all_supported_versions.size(); ++i) {
    for (AckResponse ack_response :
         {AckResponse::kDefer, AckResponse::kImmediate}) {
      params.push_back(
          TestParams(all_supported_versions[i], ack_response, true));
      if (!all_supported_versions[i].HasIetfInvariantHeader()) {
        params.push_back(
            TestParams(all_supported_versions[i], ack_response, false));
      }
    }
  }
  return params;
}

class QuicConnectionTest : public QuicTestWithParam<TestParams> {
 public:
  // For tests that do silent connection closes, no such packet is generated. In
  // order to verify the contents of the OnConnectionClosed upcall, EXPECTs
  // should invoke this method, saving the frame, and then the test can verify
  // the contents.
  void SaveConnectionCloseFrame(const QuicConnectionCloseFrame& frame,
                                ConnectionCloseSource /*source*/) {
    saved_connection_close_frame_ = frame;
    connection_close_frame_count_++;
  }

 protected:
  QuicConnectionTest()
      : connection_id_(TestConnectionId()),
        framer_(SupportedVersions(version()),
                QuicTime::Zero(),
                Perspective::IS_CLIENT,
                connection_id_.length()),
        send_algorithm_(new StrictMock<MockSendAlgorithm>),
        loss_algorithm_(new MockLossAlgorithm()),
        helper_(new TestConnectionHelper(&clock_, &random_generator_)),
        alarm_factory_(new TestAlarmFactory()),
        peer_framer_(SupportedVersions(version()),
                     QuicTime::Zero(),
                     Perspective::IS_SERVER,
                     connection_id_.length()),
        peer_creator_(connection_id_,
                      &peer_framer_,
                      /*delegate=*/nullptr),
        writer_(
            new TestPacketWriter(version(), &clock_, Perspective::IS_CLIENT)),
        connection_(connection_id_,
                    kSelfAddress,
                    kPeerAddress,
                    helper_.get(),
                    alarm_factory_.get(),
                    writer_.get(),
                    Perspective::IS_CLIENT,
                    version()),
        creator_(QuicConnectionPeer::GetPacketCreator(&connection_)),
        manager_(QuicConnectionPeer::GetSentPacketManager(&connection_)),
        frame1_(0, false, 0, absl::string_view(data1)),
        frame2_(0, false, 3, absl::string_view(data2)),
        crypto_frame_(ENCRYPTION_INITIAL, 0, absl::string_view(data1)),
        packet_number_length_(PACKET_4BYTE_PACKET_NUMBER),
        connection_id_included_(CONNECTION_ID_PRESENT),
        notifier_(&connection_),
        connection_close_frame_count_(0) {
    QUIC_DVLOG(2) << "QuicConnectionTest(" << PrintToString(GetParam()) << ")";
    connection_.set_defer_send_in_response_to_packets(GetParam().ack_response ==
                                                      AckResponse::kDefer);
    framer_.SetInitialObfuscators(TestConnectionId());
    connection_.InstallInitialCrypters(TestConnectionId());
    CrypterPair crypters;
    CryptoUtils::CreateInitialObfuscators(Perspective::IS_SERVER, version(),
                                          TestConnectionId(), &crypters);
    peer_creator_.SetEncrypter(ENCRYPTION_INITIAL,
                               std::move(crypters.encrypter));
    if (version().KnowsWhichDecrypterToUse()) {
      peer_framer_.InstallDecrypter(ENCRYPTION_INITIAL,
                                    std::move(crypters.decrypter));
    } else {
      peer_framer_.SetDecrypter(ENCRYPTION_INITIAL,
                                std::move(crypters.decrypter));
    }
    for (EncryptionLevel level :
         {ENCRYPTION_ZERO_RTT, ENCRYPTION_FORWARD_SECURE}) {
      peer_creator_.SetEncrypter(
          level, std::make_unique<NullEncrypter>(peer_framer_.perspective()));
    }
    QuicFramerPeer::SetLastSerializedServerConnectionId(
        QuicConnectionPeer::GetFramer(&connection_), connection_id_);
    QuicFramerPeer::SetLastWrittenPacketNumberLength(
        QuicConnectionPeer::GetFramer(&connection_), packet_number_length_);
    if (version().HasIetfInvariantHeader()) {
      EXPECT_TRUE(QuicConnectionPeer::GetNoStopWaitingFrames(&connection_));
    } else {
      QuicConnectionPeer::SetNoStopWaitingFrames(&connection_,
                                                 GetParam().no_stop_waiting);
    }
    QuicStreamId stream_id;
    if (QuicVersionUsesCryptoFrames(version().transport_version)) {
      stream_id = QuicUtils::GetFirstBidirectionalStreamId(
          version().transport_version, Perspective::IS_CLIENT);
    } else {
      stream_id = QuicUtils::GetCryptoStreamId(version().transport_version);
    }
    frame1_.stream_id = stream_id;
    frame2_.stream_id = stream_id;
    connection_.set_visitor(&visitor_);
    connection_.SetSessionNotifier(&notifier_);
    connection_.set_notifier(&notifier_);
    connection_.SetSendAlgorithm(send_algorithm_);
    connection_.SetLossAlgorithm(loss_algorithm_.get());
    EXPECT_CALL(*send_algorithm_, CanSend(_)).WillRepeatedly(Return(true));
    EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
        .Times(AnyNumber());
    EXPECT_CALL(*send_algorithm_, OnPacketNeutered(_)).Times(AnyNumber());
    EXPECT_CALL(*send_algorithm_, GetCongestionWindow())
        .WillRepeatedly(Return(kDefaultTCPMSS));
    EXPECT_CALL(*send_algorithm_, PacingRate(_))
        .WillRepeatedly(Return(QuicBandwidth::Zero()));
    EXPECT_CALL(*send_algorithm_, BandwidthEstimate())
        .Times(AnyNumber())
        .WillRepeatedly(Return(QuicBandwidth::Zero()));
    EXPECT_CALL(*send_algorithm_, PopulateConnectionStats(_))
        .Times(AnyNumber());
    EXPECT_CALL(*send_algorithm_, InSlowStart()).Times(AnyNumber());
    EXPECT_CALL(*send_algorithm_, InRecovery()).Times(AnyNumber());
    EXPECT_CALL(*send_algorithm_, GetCongestionControlType())
        .Times(AnyNumber());
    EXPECT_CALL(*send_algorithm_, OnApplicationLimited(_)).Times(AnyNumber());
    EXPECT_CALL(*send_algorithm_, GetCongestionControlType())
        .Times(AnyNumber());
    EXPECT_CALL(visitor_, WillingAndAbleToWrite()).Times(AnyNumber());
    EXPECT_CALL(visitor_, OnPacketDecrypted(_)).Times(AnyNumber());
    EXPECT_CALL(visitor_, OnCanWrite())
        .WillRepeatedly(Invoke(&notifier_, &SimpleSessionNotifier::OnCanWrite));
    EXPECT_CALL(visitor_, ShouldKeepConnectionAlive())
        .WillRepeatedly(Return(false));
    EXPECT_CALL(visitor_, OnCongestionWindowChange(_)).Times(AnyNumber());
    EXPECT_CALL(visitor_, OnPacketReceived(_, _, _)).Times(AnyNumber());
    EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_)).Times(AnyNumber());
    EXPECT_CALL(visitor_, OnOneRttPacketAcknowledged())
        .Times(testing::AtMost(1));
    EXPECT_CALL(*loss_algorithm_, GetLossTimeout())
        .WillRepeatedly(Return(QuicTime::Zero()));
    EXPECT_CALL(*loss_algorithm_, DetectLosses(_, _, _, _, _, _))
        .Times(AnyNumber());
    EXPECT_CALL(visitor_, GetHandshakeState())
        .WillRepeatedly(Return(HANDSHAKE_START));
    if (connection_.version().KnowsWhichDecrypterToUse()) {
      connection_.InstallDecrypter(
          ENCRYPTION_FORWARD_SECURE,
          std::make_unique<NullDecrypter>(Perspective::IS_CLIENT));
    }
    peer_creator_.SetDefaultPeerAddress(kSelfAddress);
  }

  QuicConnectionTest(const QuicConnectionTest&) = delete;
  QuicConnectionTest& operator=(const QuicConnectionTest&) = delete;

  ParsedQuicVersion version() { return GetParam().version; }

  QuicStopWaitingFrame* stop_waiting() {
    QuicConnectionPeer::PopulateStopWaitingFrame(&connection_, &stop_waiting_);
    return &stop_waiting_;
  }

  QuicPacketNumber least_unacked() {
    if (writer_->stop_waiting_frames().empty()) {
      return QuicPacketNumber();
    }
    return writer_->stop_waiting_frames()[0].least_unacked;
  }

  void use_tagging_decrypter() { writer_->use_tagging_decrypter(); }

  void SetClientConnectionId(const QuicConnectionId& client_connection_id) {
    connection_.set_client_connection_id(client_connection_id);
    writer_->framer()->framer()->SetExpectedClientConnectionIdLength(
        client_connection_id.length());
  }

  void SetDecrypter(EncryptionLevel level,
                    std::unique_ptr<QuicDecrypter> decrypter) {
    if (connection_.version().KnowsWhichDecrypterToUse()) {
      connection_.InstallDecrypter(level, std::move(decrypter));
    } else {
      connection_.SetDecrypter(level, std::move(decrypter));
    }
  }

  void ProcessPacket(uint64_t number) {
    EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(1);
    ProcessDataPacket(number);
    if (connection_.GetSendAlarm()->IsSet()) {
      connection_.GetSendAlarm()->Fire();
    }
  }

  void ProcessReceivedPacket(const QuicSocketAddress& self_address,
                             const QuicSocketAddress& peer_address,
                             const QuicReceivedPacket& packet) {
    connection_.ProcessUdpPacket(self_address, peer_address, packet);
    if (connection_.GetSendAlarm()->IsSet()) {
      connection_.GetSendAlarm()->Fire();
    }
  }

  QuicFrame MakeCryptoFrame() const {
    if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
      return QuicFrame(new QuicCryptoFrame(crypto_frame_));
    }
    return QuicFrame(QuicStreamFrame(
        QuicUtils::GetCryptoStreamId(connection_.transport_version()), false,
        0u, absl::string_view()));
  }

  void ProcessFramePacket(QuicFrame frame) {
    ProcessFramePacketWithAddresses(frame, kSelfAddress, kPeerAddress,
                                    ENCRYPTION_FORWARD_SECURE);
  }

  void ProcessFramePacketWithAddresses(QuicFrame frame,
                                       QuicSocketAddress self_address,
                                       QuicSocketAddress peer_address,
                                       EncryptionLevel level) {
    QuicFrames frames;
    frames.push_back(QuicFrame(frame));
    return ProcessFramesPacketWithAddresses(frames, self_address, peer_address,
                                            level);
  }

  std::unique_ptr<QuicReceivedPacket> ConstructPacket(QuicFrames frames,
                                                      EncryptionLevel level,
                                                      char* buffer,
                                                      size_t buffer_len) {
    QUICHE_DCHECK(peer_framer_.HasEncrypterOfEncryptionLevel(level));
    peer_creator_.set_encryption_level(level);
    QuicPacketCreatorPeer::SetSendVersionInPacket(
        &peer_creator_,
        level < ENCRYPTION_FORWARD_SECURE &&
            connection_.perspective() == Perspective::IS_SERVER);

    SerializedPacket serialized_packet =
        QuicPacketCreatorPeer::SerializeAllFrames(&peer_creator_, frames,
                                                  buffer, buffer_len);
    return std::make_unique<QuicReceivedPacket>(
        serialized_packet.encrypted_buffer, serialized_packet.encrypted_length,
        clock_.Now());
  }

  void ProcessFramesPacketWithAddresses(QuicFrames frames,
                                        QuicSocketAddress self_address,
                                        QuicSocketAddress peer_address,
                                        EncryptionLevel level) {
    char buffer[kMaxOutgoingPacketSize];
    connection_.ProcessUdpPacket(
        self_address, peer_address,
        *ConstructPacket(std::move(frames), level, buffer,
                         kMaxOutgoingPacketSize));
    if (connection_.GetSendAlarm()->IsSet()) {
      connection_.GetSendAlarm()->Fire();
    }
  }

  // Bypassing the packet creator is unrealistic, but allows us to process
  // packets the QuicPacketCreator won't allow us to create.
  void ForceProcessFramePacket(QuicFrame frame) {
    QuicFrames frames;
    frames.push_back(QuicFrame(frame));
    bool send_version = connection_.perspective() == Perspective::IS_SERVER;
    if (connection_.version().KnowsWhichDecrypterToUse()) {
      send_version = true;
    }
    QuicPacketCreatorPeer::SetSendVersionInPacket(&peer_creator_, send_version);
    QuicPacketHeader header;
    QuicPacketCreatorPeer::FillPacketHeader(&peer_creator_, &header);
    char encrypted_buffer[kMaxOutgoingPacketSize];
    size_t length = peer_framer_.BuildDataPacket(
        header, frames, encrypted_buffer, kMaxOutgoingPacketSize,
        ENCRYPTION_INITIAL);
    QUICHE_DCHECK_GT(length, 0u);

    const size_t encrypted_length = peer_framer_.EncryptInPlace(
        ENCRYPTION_INITIAL, header.packet_number,
        GetStartOfEncryptedData(peer_framer_.version().transport_version,
                                header),
        length, kMaxOutgoingPacketSize, encrypted_buffer);
    QUICHE_DCHECK_GT(encrypted_length, 0u);

    connection_.ProcessUdpPacket(
        kSelfAddress, kPeerAddress,
        QuicReceivedPacket(encrypted_buffer, encrypted_length, clock_.Now()));
  }

  size_t ProcessFramePacketAtLevel(uint64_t number,
                                   QuicFrame frame,
                                   EncryptionLevel level) {
    QuicFrames frames;
    frames.push_back(frame);
    return ProcessFramesPacketAtLevel(number, frames, level);
  }

  size_t ProcessFramesPacketAtLevel(uint64_t number,
                                    const QuicFrames& frames,
                                    EncryptionLevel level) {
    QuicPacketHeader header = ConstructPacketHeader(number, level);
    // Set the correct encryption level and encrypter on peer_creator and
    // peer_framer, respectively.
    peer_creator_.set_encryption_level(level);
    if (QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_) >
        ENCRYPTION_INITIAL) {
      peer_framer_.SetEncrypter(
          QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_),
          std::make_unique<TaggingEncrypter>(0x01));
      // Set the corresponding decrypter.
      if (connection_.version().KnowsWhichDecrypterToUse()) {
        connection_.InstallDecrypter(
            QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_),
            std::make_unique<StrictTaggingDecrypter>(0x01));
      } else {
        connection_.SetDecrypter(
            QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_),
            std::make_unique<StrictTaggingDecrypter>(0x01));
      }
    }
    std::unique_ptr<QuicPacket> packet(ConstructPacket(header, frames));

    char buffer[kMaxOutgoingPacketSize];
    size_t encrypted_length =
        peer_framer_.EncryptPayload(level, QuicPacketNumber(number), *packet,
                                    buffer, kMaxOutgoingPacketSize);
    connection_.ProcessUdpPacket(
        kSelfAddress, kPeerAddress,
        QuicReceivedPacket(buffer, encrypted_length, clock_.Now(), false));
    if (connection_.GetSendAlarm()->IsSet()) {
      connection_.GetSendAlarm()->Fire();
    }
    return encrypted_length;
  }

  struct PacketInfo {
    PacketInfo(uint64_t packet_number, QuicFrames frames, EncryptionLevel level)
        : packet_number(packet_number), frames(frames), level(level) {}

    uint64_t packet_number;
    QuicFrames frames;
    EncryptionLevel level;
  };

  size_t ProcessCoalescedPacket(std::vector<PacketInfo> packets) {
    char coalesced_buffer[kMaxOutgoingPacketSize];
    size_t coalesced_size = 0;
    bool contains_initial = false;
    for (const auto& packet : packets) {
      QuicPacketHeader header =
          ConstructPacketHeader(packet.packet_number, packet.level);
      // Set the correct encryption level and encrypter on peer_creator and
      // peer_framer, respectively.
      peer_creator_.set_encryption_level(packet.level);
      if (packet.level == ENCRYPTION_INITIAL) {
        contains_initial = true;
      }
      if (QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_) >
          ENCRYPTION_INITIAL) {
        peer_framer_.SetEncrypter(
            QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_),
            std::make_unique<TaggingEncrypter>(0x01));
        // Set the corresponding decrypter.
        if (connection_.version().KnowsWhichDecrypterToUse()) {
          connection_.InstallDecrypter(
              QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_),
              std::make_unique<StrictTaggingDecrypter>(0x01));
        } else {
          connection_.SetDecrypter(
              QuicPacketCreatorPeer::GetEncryptionLevel(&peer_creator_),
              std::make_unique<StrictTaggingDecrypter>(0x01));
        }
      }
      std::unique_ptr<QuicPacket> constructed_packet(
          ConstructPacket(header, packet.frames));

      char buffer[kMaxOutgoingPacketSize];
      size_t encrypted_length = peer_framer_.EncryptPayload(
          packet.level, QuicPacketNumber(packet.packet_number),
          *constructed_packet, buffer, kMaxOutgoingPacketSize);
      QUICHE_DCHECK_LE(coalesced_size + encrypted_length,
                       kMaxOutgoingPacketSize);
      memcpy(coalesced_buffer + coalesced_size, buffer, encrypted_length);
      coalesced_size += encrypted_length;
    }
    if (contains_initial) {
      // Padded coalesced packet to full if it contains initial packet.
      memset(coalesced_buffer + coalesced_size, '0',
             kMaxOutgoingPacketSize - coalesced_size);
    }
    connection_.ProcessUdpPacket(
        kSelfAddress, kPeerAddress,
        QuicReceivedPacket(coalesced_buffer, coalesced_size, clock_.Now(),
                           false));
    if (connection_.GetSendAlarm()->IsSet()) {
      connection_.GetSendAlarm()->Fire();
    }
    return coalesced_size;
  }

  size_t ProcessDataPacket(uint64_t number) {
    return ProcessDataPacketAtLevel(number, false, ENCRYPTION_FORWARD_SECURE);
  }

  size_t ProcessDataPacket(QuicPacketNumber packet_number) {
    return ProcessDataPacketAtLevel(packet_number, false,
                                    ENCRYPTION_FORWARD_SECURE);
  }

  size_t ProcessDataPacketAtLevel(QuicPacketNumber packet_number,
                                  bool has_stop_waiting,
                                  EncryptionLevel level) {
    return ProcessDataPacketAtLevel(packet_number.ToUint64(), has_stop_waiting,
                                    level);
  }

  size_t ProcessCryptoPacketAtLevel(uint64_t number, EncryptionLevel level) {
    QuicPacketHeader header = ConstructPacketHeader(number, level);
    QuicFrames frames;
    if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
      frames.push_back(QuicFrame(&crypto_frame_));
    } else {
      frames.push_back(QuicFrame(frame1_));
    }
    if (level == ENCRYPTION_INITIAL) {
      frames.push_back(QuicFrame(QuicPaddingFrame(-1)));
    }
    std::unique_ptr<QuicPacket> packet = ConstructPacket(header, frames);
    char buffer[kMaxOutgoingPacketSize];
    peer_creator_.set_encryption_level(level);
    size_t encrypted_length =
        peer_framer_.EncryptPayload(level, QuicPacketNumber(number), *packet,
                                    buffer, kMaxOutgoingPacketSize);
    connection_.ProcessUdpPacket(
        kSelfAddress, kPeerAddress,
        QuicReceivedPacket(buffer, encrypted_length, clock_.Now(), false));
    if (connection_.GetSendAlarm()->IsSet()) {
      connection_.GetSendAlarm()->Fire();
    }
    return encrypted_length;
  }

  size_t ProcessDataPacketAtLevel(uint64_t number,
                                  bool has_stop_waiting,
                                  EncryptionLevel level) {
    std::unique_ptr<QuicPacket> packet(
        ConstructDataPacket(number, has_stop_waiting, level));
    char buffer[kMaxOutgoingPacketSize];
    peer_creator_.set_encryption_level(level);
    size_t encrypted_length =
        peer_framer_.EncryptPayload(level, QuicPacketNumber(number), *packet,
                                    buffer, kMaxOutgoingPacketSize);
    connection_.ProcessUdpPacket(
        kSelfAddress, kPeerAddress,
        QuicReceivedPacket(buffer, encrypted_length, clock_.Now(), false));
    if (connection_.GetSendAlarm()->IsSet()) {
      connection_.GetSendAlarm()->Fire();
    }
    return encrypted_length;
  }

  void ProcessClosePacket(uint64_t number) {
    std::unique_ptr<QuicPacket> packet(ConstructClosePacket(number));
    char buffer[kMaxOutgoingPacketSize];
    size_t encrypted_length = peer_framer_.EncryptPayload(
        ENCRYPTION_FORWARD_SECURE, QuicPacketNumber(number), *packet, buffer,
        kMaxOutgoingPacketSize);
    connection_.ProcessUdpPacket(
        kSelfAddress, kPeerAddress,
        QuicReceivedPacket(buffer, encrypted_length, QuicTime::Zero(), false));
  }

  QuicByteCount SendStreamDataToPeer(QuicStreamId id,
                                     absl::string_view data,
                                     QuicStreamOffset offset,
                                     StreamSendingState state,
                                     QuicPacketNumber* last_packet) {
    QuicByteCount packet_size;
    // Save the last packet's size.
    EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
        .Times(AnyNumber())
        .WillRepeatedly(SaveArg<3>(&packet_size));
    connection_.SendStreamDataWithString(id, data, offset, state);
    if (last_packet != nullptr) {
      *last_packet = creator_->packet_number();
    }
    EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
        .Times(AnyNumber());
    return packet_size;
  }

  void SendAckPacketToPeer() {
    EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _)).Times(1);
    {
      QuicConnection::ScopedPacketFlusher flusher(&connection_);
      connection_.SendAck();
    }
    EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
        .Times(AnyNumber());
  }

  void SendRstStream(QuicStreamId id,
                     QuicRstStreamErrorCode error,
                     QuicStreamOffset bytes_written) {
    notifier_.WriteOrBufferRstStream(id, error, bytes_written);
    connection_.OnStreamReset(id, error);
  }

  void SendPing() { notifier_.WriteOrBufferPing(); }

  MessageStatus SendMessage(absl::string_view message) {
    connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
    QuicMemSlice slice(QuicBuffer::Copy(
        connection_.helper()->GetStreamSendBufferAllocator(), message));
    return connection_.SendMessage(1, absl::MakeSpan(&slice, 1), false);
  }

  void ProcessAckPacket(uint64_t packet_number, QuicAckFrame* frame) {
    if (packet_number > 1) {
      QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, packet_number - 1);
    } else {
      QuicPacketCreatorPeer::ClearPacketNumber(&peer_creator_);
    }
    ProcessFramePacket(QuicFrame(frame));
  }

  void ProcessAckPacket(QuicAckFrame* frame) {
    ProcessFramePacket(QuicFrame(frame));
  }

  void ProcessStopWaitingPacket(QuicStopWaitingFrame frame) {
    ProcessFramePacket(QuicFrame(frame));
  }

  size_t ProcessStopWaitingPacketAtLevel(uint64_t number,
                                         QuicStopWaitingFrame frame,
                                         EncryptionLevel /*level*/) {
    return ProcessFramePacketAtLevel(number, QuicFrame(frame),
                                     ENCRYPTION_ZERO_RTT);
  }

  void ProcessGoAwayPacket(QuicGoAwayFrame* frame) {
    ProcessFramePacket(QuicFrame(frame));
  }

  bool IsMissing(uint64_t number) {
    return IsAwaitingPacket(connection_.ack_frame(), QuicPacketNumber(number),
                            QuicPacketNumber());
  }

  std::unique_ptr<QuicPacket> ConstructPacket(const QuicPacketHeader& header,
                                              const QuicFrames& frames) {
    auto packet = BuildUnsizedDataPacket(&peer_framer_, header, frames);
    EXPECT_NE(nullptr, packet.get());
    return packet;
  }

  QuicPacketHeader ConstructPacketHeader(uint64_t number,
                                         EncryptionLevel level) {
    QuicPacketHeader header;
    if (peer_framer_.version().HasIetfInvariantHeader() &&
        level < ENCRYPTION_FORWARD_SECURE) {
      // Set long header type accordingly.
      header.version_flag = true;
      header.form = IETF_QUIC_LONG_HEADER_PACKET;
      header.long_packet_type = EncryptionlevelToLongHeaderType(level);
      if (QuicVersionHasLongHeaderLengths(
              peer_framer_.version().transport_version)) {
        header.length_length = VARIABLE_LENGTH_INTEGER_LENGTH_2;
        if (header.long_packet_type == INITIAL) {
          header.retry_token_length_length = VARIABLE_LENGTH_INTEGER_LENGTH_1;
        }
      }
    }
    // Set connection_id to peer's in memory representation as this data packet
    // is created by peer_framer.
    if (peer_framer_.perspective() == Perspective::IS_SERVER) {
      header.source_connection_id = connection_id_;
      header.source_connection_id_included = connection_id_included_;
      header.destination_connection_id_included = CONNECTION_ID_ABSENT;
    } else {
      header.destination_connection_id = connection_id_;
      header.destination_connection_id_included = connection_id_included_;
    }
    if (peer_framer_.version().HasIetfInvariantHeader() &&
        peer_framer_.perspective() == Perspective::IS_SERVER) {
      if (!connection_.client_connection_id().IsEmpty()) {
        header.destination_connection_id = connection_.client_connection_id();
        header.destination_connection_id_included = CONNECTION_ID_PRESENT;
      } else {
        header.destination_connection_id_included = CONNECTION_ID_ABSENT;
      }
      if (header.version_flag) {
        header.source_connection_id = connection_id_;
        header.source_connection_id_included = CONNECTION_ID_PRESENT;
        if (GetParam().version.handshake_protocol == PROTOCOL_QUIC_CRYPTO &&
            header.long_packet_type == ZERO_RTT_PROTECTED) {
          header.nonce = &kTestDiversificationNonce;
        }
      }
    }
    header.packet_number_length = packet_number_length_;
    header.packet_number = QuicPacketNumber(number);
    return header;
  }

  std::unique_ptr<QuicPacket> ConstructDataPacket(uint64_t number,
                                                  bool has_stop_waiting,
                                                  EncryptionLevel level) {
    QuicPacketHeader header = ConstructPacketHeader(number, level);
    QuicFrames frames;
    if (VersionHasIetfQuicFrames(version().transport_version) &&
        (level == ENCRYPTION_INITIAL || level == ENCRYPTION_HANDSHAKE)) {
      frames.push_back(QuicFrame(QuicPingFrame()));
      frames.push_back(QuicFrame(QuicPaddingFrame(100)));
    } else {
      frames.push_back(QuicFrame(frame1_));
      if (has_stop_waiting) {
        frames.push_back(QuicFrame(stop_waiting_));
      }
    }
    return ConstructPacket(header, frames);
  }

  std::unique_ptr<SerializedPacket> ConstructProbingPacket() {
    peer_creator_.set_encryption_level(ENCRYPTION_FORWARD_SECURE);
    if (VersionHasIetfQuicFrames(version().transport_version)) {
      QuicPathFrameBuffer payload = {
          {0xde, 0xad, 0xbe, 0xef, 0xba, 0xdc, 0x0f, 0xfe}};
      return QuicPacketCreatorPeer::
          SerializePathChallengeConnectivityProbingPacket(&peer_creator_,
                                                          payload);
    }
    return QuicPacketCreatorPeer::SerializeConnectivityProbingPacket(
        &peer_creator_);
  }

  std::unique_ptr<QuicPacket> ConstructClosePacket(uint64_t number) {
    peer_creator_.set_encryption_level(ENCRYPTION_FORWARD_SECURE);
    QuicPacketHeader header;
    // Set connection_id to peer's in memory representation as this connection
    // close packet is created by peer_framer.
    if (peer_framer_.perspective() == Perspective::IS_SERVER) {
      header.source_connection_id = connection_id_;
      header.destination_connection_id_included = CONNECTION_ID_ABSENT;
      if (!peer_framer_.version().HasIetfInvariantHeader()) {
        header.source_connection_id_included = CONNECTION_ID_PRESENT;
      }
    } else {
      header.destination_connection_id = connection_id_;
      if (peer_framer_.version().HasIetfInvariantHeader()) {
        header.destination_connection_id_included = CONNECTION_ID_ABSENT;
      }
    }

    header.packet_number = QuicPacketNumber(number);

    QuicErrorCode kQuicErrorCode = QUIC_PEER_GOING_AWAY;
    QuicConnectionCloseFrame qccf(peer_framer_.transport_version(),
                                  kQuicErrorCode, NO_IETF_QUIC_ERROR, "",
                                  /*transport_close_frame_type=*/0);
    QuicFrames frames;
    frames.push_back(QuicFrame(&qccf));
    return ConstructPacket(header, frames);
  }

  QuicTime::Delta DefaultRetransmissionTime() {
    return QuicTime::Delta::FromMilliseconds(kDefaultRetransmissionTimeMs);
  }

  QuicTime::Delta DefaultDelayedAckTime() {
    return QuicTime::Delta::FromMilliseconds(kDefaultDelayedAckTimeMs);
  }

  const QuicStopWaitingFrame InitStopWaitingFrame(uint64_t least_unacked) {
    QuicStopWaitingFrame frame;
    frame.least_unacked = QuicPacketNumber(least_unacked);
    return frame;
  }

  // Construct a ack_frame that acks all packet numbers between 1 and
  // |largest_acked|, except |missing|.
  // REQUIRES: 1 <= |missing| < |largest_acked|
  QuicAckFrame ConstructAckFrame(uint64_t largest_acked, uint64_t missing) {
    return ConstructAckFrame(QuicPacketNumber(largest_acked),
                             QuicPacketNumber(missing));
  }

  QuicAckFrame ConstructAckFrame(QuicPacketNumber largest_acked,
                                 QuicPacketNumber missing) {
    if (missing == QuicPacketNumber(1)) {
      return InitAckFrame({{missing + 1, largest_acked + 1}});
    }
    return InitAckFrame(
        {{QuicPacketNumber(1), missing}, {missing + 1, largest_acked + 1}});
  }

  // Undo nacking a packet within the frame.
  void AckPacket(QuicPacketNumber arrived, QuicAckFrame* frame) {
    EXPECT_FALSE(frame->packets.Contains(arrived));
    frame->packets.Add(arrived);
  }

  void TriggerConnectionClose() {
    // Send an erroneous packet to close the connection.
    EXPECT_CALL(visitor_,
                OnConnectionClosed(_, ConnectionCloseSource::FROM_SELF))
        .WillOnce(Invoke(this, &QuicConnectionTest::SaveConnectionCloseFrame));

    EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
    // Triggers a connection by receiving ACK of unsent packet.
    QuicAckFrame frame = InitAckFrame(10000);
    ProcessAckPacket(1, &frame);
    EXPECT_FALSE(QuicConnectionPeer::GetConnectionClosePacket(&connection_) ==
                 nullptr);
    EXPECT_EQ(1, connection_close_frame_count_);
    EXPECT_THAT(saved_connection_close_frame_.quic_error_code,
                IsError(QUIC_INVALID_ACK_DATA));
  }

  void BlockOnNextWrite() {
    writer_->BlockOnNextWrite();
    EXPECT_CALL(visitor_, OnWriteBlocked()).Times(AtLeast(1));
  }

  void SimulateNextPacketTooLarge() { writer_->SimulateNextPacketTooLarge(); }

  void AlwaysGetPacketTooLarge() { writer_->AlwaysGetPacketTooLarge(); }

  void SetWritePauseTimeDelta(QuicTime::Delta delta) {
    writer_->SetWritePauseTimeDelta(delta);
  }

  void CongestionBlockWrites() {
    EXPECT_CALL(*send_algorithm_, CanSend(_))
        .WillRepeatedly(testing::Return(false));
  }

  void CongestionUnblockWrites() {
    EXPECT_CALL(*send_algorithm_, CanSend(_))
        .WillRepeatedly(testing::Return(true));
  }

  void set_perspective(Perspective perspective) {
    connection_.set_perspective(perspective);
    if (perspective == Perspective::IS_SERVER) {
      QuicConfig config;
      if (!GetQuicReloadableFlag(
              quic_remove_connection_migration_connection_option)) {
        QuicTagVector connection_options;
        connection_options.push_back(kRVCM);
        config.SetInitialReceivedConnectionOptions(connection_options);
      }
      EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
      connection_.SetFromConfig(config);

      connection_.set_can_truncate_connection_ids(true);
      QuicConnectionPeer::SetNegotiatedVersion(&connection_);
      connection_.OnSuccessfulVersionNegotiation();
    }
    QuicFramerPeer::SetPerspective(&peer_framer_,
                                   QuicUtils::InvertPerspective(perspective));
    peer_framer_.SetInitialObfuscators(TestConnectionId());
    for (EncryptionLevel level : {ENCRYPTION_ZERO_RTT, ENCRYPTION_HANDSHAKE,
                                  ENCRYPTION_FORWARD_SECURE}) {
      if (peer_framer_.HasEncrypterOfEncryptionLevel(level)) {
        peer_creator_.SetEncrypter(
            level, std::make_unique<NullEncrypter>(peer_framer_.perspective()));
      }
    }
  }

  void set_packets_between_probes_base(
      const QuicPacketCount packets_between_probes_base) {
    QuicConnectionPeer::ReInitializeMtuDiscoverer(
        &connection_, packets_between_probes_base,
        QuicPacketNumber(packets_between_probes_base));
  }

  bool IsDefaultTestConfiguration() {
    TestParams p = GetParam();
    return p.ack_response == AckResponse::kImmediate &&
           p.version == AllSupportedVersions()[0] && p.no_stop_waiting;
  }

  void TestConnectionCloseQuicErrorCode(QuicErrorCode expected_code) {
    // Not strictly needed for this test, but is commonly done.
    EXPECT_FALSE(QuicConnectionPeer::GetConnectionClosePacket(&connection_) ==
                 nullptr);
    const std::vector<QuicConnectionCloseFrame>& connection_close_frames =
        writer_->connection_close_frames();
    ASSERT_EQ(1u, connection_close_frames.size());

    EXPECT_THAT(connection_close_frames[0].quic_error_code,
                IsError(expected_code));

    if (!VersionHasIetfQuicFrames(version().transport_version)) {
      EXPECT_THAT(connection_close_frames[0].wire_error_code,
                  IsError(expected_code));
      EXPECT_EQ(GOOGLE_QUIC_CONNECTION_CLOSE,
                connection_close_frames[0].close_type);
      return;
    }

    QuicErrorCodeToIetfMapping mapping =
        QuicErrorCodeToTransportErrorCode(expected_code);

    if (mapping.is_transport_close) {
      // This Google QUIC Error Code maps to a transport close,
      EXPECT_EQ(IETF_QUIC_TRANSPORT_CONNECTION_CLOSE,
                connection_close_frames[0].close_type);
    } else {
      // This maps to an application close.
      EXPECT_EQ(IETF_QUIC_APPLICATION_CONNECTION_CLOSE,
                connection_close_frames[0].close_type);
    }
    EXPECT_EQ(mapping.error_code, connection_close_frames[0].wire_error_code);
  }

  void MtuDiscoveryTestInit() {
    set_perspective(Perspective::IS_SERVER);
    QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
    if (version().SupportsAntiAmplificationLimit()) {
      QuicConnectionPeer::SetAddressValidated(&connection_);
    }
    connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
    peer_creator_.set_encryption_level(ENCRYPTION_FORWARD_SECURE);
    // QuicFramer::GetMaxPlaintextSize uses the smallest max plaintext size
    // across all encrypters. The initial encrypter used with IETF QUIC has a
    // 16-byte overhead, while the NullEncrypter used throughout this test has a
    // 12-byte overhead. This test tests behavior that relies on computing the
    // packet size correctly, so by unsetting the initial encrypter, we avoid
    // having a mismatch between the overheads for the encrypters used. In
    // non-test scenarios all encrypters used for a given connection have the
    // same overhead, either 12 bytes for ones using Google QUIC crypto, or 16
    // bytes for ones using TLS.
    connection_.SetEncrypter(ENCRYPTION_INITIAL, nullptr);
    // Prevent packets from being coalesced.
    EXPECT_CALL(visitor_, GetHandshakeState())
        .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));
    EXPECT_TRUE(connection_.connected());
  }

  void PathProbeTestInit(Perspective perspective,
                         bool receive_new_server_connection_id = true) {
    set_perspective(perspective);
    connection_.CreateConnectionIdManager();
    EXPECT_EQ(connection_.perspective(), perspective);
    if (perspective == Perspective::IS_SERVER) {
      QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
    }
    connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
    peer_creator_.set_encryption_level(ENCRYPTION_FORWARD_SECURE);
    // Discard INITIAL key.
    connection_.RemoveEncrypter(ENCRYPTION_INITIAL);
    connection_.NeuterUnencryptedPackets();
    // Prevent packets from being coalesced.
    EXPECT_CALL(visitor_, GetHandshakeState())
        .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));
    if (version().SupportsAntiAmplificationLimit() &&
        perspective == Perspective::IS_SERVER) {
      QuicConnectionPeer::SetAddressValidated(&connection_);
    }
    // Clear direct_peer_address.
    QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
    // Clear effective_peer_address, it is the same as direct_peer_address for
    // this test.
    QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                                QuicSocketAddress());
    EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

    if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
      EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
    } else {
      EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
    }
    QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 2);
    ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress,
                                    kPeerAddress, ENCRYPTION_FORWARD_SECURE);
    EXPECT_EQ(kPeerAddress, connection_.peer_address());
    EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
    if (perspective == Perspective::IS_CLIENT &&
        receive_new_server_connection_id && version().HasIetfQuicFrames()) {
      QuicNewConnectionIdFrame frame;
      frame.connection_id = TestConnectionId(1234);
      ASSERT_NE(frame.connection_id, connection_.connection_id());
      frame.stateless_reset_token =
          QuicUtils::GenerateStatelessResetToken(frame.connection_id);
      frame.retire_prior_to = 0u;
      frame.sequence_number = 1u;
      connection_.OnNewConnectionIdFrame(frame);
    }
  }

  void TestClientRetryHandling(bool invalid_retry_tag,
                               bool missing_original_id_in_config,
                               bool wrong_original_id_in_config,
                               bool missing_retry_id_in_config,
                               bool wrong_retry_id_in_config);

  void TestReplaceConnectionIdFromInitial();

  QuicConnectionId connection_id_;
  QuicFramer framer_;

  MockSendAlgorithm* send_algorithm_;
  std::unique_ptr<MockLossAlgorithm> loss_algorithm_;
  MockClock clock_;
  MockRandom random_generator_;
  SimpleBufferAllocator buffer_allocator_;
  std::unique_ptr<TestConnectionHelper> helper_;
  std::unique_ptr<TestAlarmFactory> alarm_factory_;
  QuicFramer peer_framer_;
  QuicPacketCreator peer_creator_;
  std::unique_ptr<TestPacketWriter> writer_;
  TestConnection connection_;
  QuicPacketCreator* creator_;
  QuicSentPacketManager* manager_;
  StrictMock<MockQuicConnectionVisitor> visitor_;

  QuicStreamFrame frame1_;
  QuicStreamFrame frame2_;
  QuicCryptoFrame crypto_frame_;
  QuicAckFrame ack_;
  QuicStopWaitingFrame stop_waiting_;
  QuicPacketNumberLength packet_number_length_;
  QuicConnectionIdIncluded connection_id_included_;

  SimpleSessionNotifier notifier_;

  QuicConnectionCloseFrame saved_connection_close_frame_;
  int connection_close_frame_count_;
};

// Run all end to end tests with all supported versions.
INSTANTIATE_TEST_SUITE_P(QuicConnectionTests, QuicConnectionTest,
                         ::testing::ValuesIn(GetTestParams()),
                         ::testing::PrintToStringParamName());

// These two tests ensure that the QuicErrorCode mapping works correctly.
// Both tests expect to see a Google QUIC close if not running IETF QUIC.
// If running IETF QUIC, the first will generate a transport connection
// close, the second an application connection close.
// The connection close codes for the two tests are manually chosen;
// they are expected to always map to transport- and application-
// closes, respectively. If that changes, new codes should be chosen.
TEST_P(QuicConnectionTest, CloseErrorCodeTestTransport) {
  EXPECT_TRUE(connection_.connected());
  EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
  connection_.CloseConnection(
      IETF_QUIC_PROTOCOL_VIOLATION, "Should be transport close",
      ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
  EXPECT_FALSE(connection_.connected());
  TestConnectionCloseQuicErrorCode(IETF_QUIC_PROTOCOL_VIOLATION);
}

// Test that the IETF QUIC Error code mapping function works
// properly for application connection close codes.
TEST_P(QuicConnectionTest, CloseErrorCodeTestApplication) {
  EXPECT_TRUE(connection_.connected());
  EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
  connection_.CloseConnection(
      QUIC_HEADERS_STREAM_DATA_DECOMPRESS_FAILURE,
      "Should be application close",
      ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
  EXPECT_FALSE(connection_.connected());
  TestConnectionCloseQuicErrorCode(QUIC_HEADERS_STREAM_DATA_DECOMPRESS_FAILURE);
}

TEST_P(QuicConnectionTest, SelfAddressChangeAtClient) {
  EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));

  EXPECT_EQ(Perspective::IS_CLIENT, connection_.perspective());
  EXPECT_TRUE(connection_.connected());

  if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
    EXPECT_CALL(visitor_, OnCryptoFrame(_));
  } else {
    EXPECT_CALL(visitor_, OnStreamFrame(_));
  }
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress, kPeerAddress,
                                  ENCRYPTION_INITIAL);
  // Cause change in self_address.
  QuicIpAddress host;
  host.FromString("1.1.1.1");
  QuicSocketAddress self_address(host, 123);
  if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
    EXPECT_CALL(visitor_, OnCryptoFrame(_));
  } else {
    EXPECT_CALL(visitor_, OnStreamFrame(_));
  }
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), self_address, kPeerAddress,
                                  ENCRYPTION_INITIAL);
  EXPECT_TRUE(connection_.connected());
}

TEST_P(QuicConnectionTest, SelfAddressChangeAtServer) {
  set_perspective(Perspective::IS_SERVER);
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

  EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());
  EXPECT_TRUE(connection_.connected());

  if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
    EXPECT_CALL(visitor_, OnCryptoFrame(_));
  } else {
    EXPECT_CALL(visitor_, OnStreamFrame(_));
  }
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress, kPeerAddress,
                                  ENCRYPTION_INITIAL);
  // Cause change in self_address.
  QuicIpAddress host;
  host.FromString("1.1.1.1");
  QuicSocketAddress self_address(host, 123);
  EXPECT_CALL(visitor_, AllowSelfAddressChange()).WillOnce(Return(false));
  if (version().handshake_protocol == PROTOCOL_TLS1_3) {
    EXPECT_CALL(visitor_, BeforeConnectionCloseSent());
  }
  EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), self_address, kPeerAddress,
                                  ENCRYPTION_INITIAL);
  EXPECT_FALSE(connection_.connected());
  TestConnectionCloseQuicErrorCode(QUIC_ERROR_MIGRATING_ADDRESS);
}

TEST_P(QuicConnectionTest, AllowSelfAddressChangeToMappedIpv4AddressAtServer) {
  set_perspective(Perspective::IS_SERVER);
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);

  EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());
  EXPECT_TRUE(connection_.connected());

  if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
    EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(3);
  } else {
    EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(3);
  }
  QuicIpAddress host;
  host.FromString("1.1.1.1");
  QuicSocketAddress self_address1(host, 443);
  connection_.SetSelfAddress(self_address1);
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), self_address1,
                                  kPeerAddress, ENCRYPTION_INITIAL);
  // Cause self_address change to mapped Ipv4 address.
  QuicIpAddress host2;
  host2.FromString(
      absl::StrCat("::ffff:", connection_.self_address().host().ToString()));
  QuicSocketAddress self_address2(host2, connection_.self_address().port());
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), self_address2,
                                  kPeerAddress, ENCRYPTION_INITIAL);
  EXPECT_TRUE(connection_.connected());
  // self_address change back to Ipv4 address.
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), self_address1,
                                  kPeerAddress, ENCRYPTION_INITIAL);
  EXPECT_TRUE(connection_.connected());
}

TEST_P(QuicConnectionTest, ClientAddressChangeAndPacketReordered) {
  set_perspective(Perspective::IS_SERVER);
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
  EXPECT_CALL(visitor_, GetHandshakeState())
      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));

  // Clear direct_peer_address.
  QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
  // Clear effective_peer_address, it is the same as direct_peer_address for
  // this test.
  QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                              QuicSocketAddress());

  if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
    EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
  } else {
    EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
  }
  QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 5);
  const QuicSocketAddress kNewPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(),
                        /*port=*/23456);
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress,
                                  kNewPeerAddress, ENCRYPTION_INITIAL);
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());

  // Decrease packet number to simulate out-of-order packets.
  QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 4);
  // This is an old packet, do not migrate.
  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress, kPeerAddress,
                                  ENCRYPTION_INITIAL);
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
}

TEST_P(QuicConnectionTest, PeerPortChangeAtServer) {
  set_perspective(Perspective::IS_SERVER);
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
  EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());
  connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
  // Prevent packets from being coalesced.
  EXPECT_CALL(visitor_, GetHandshakeState())
      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));
  if (version().SupportsAntiAmplificationLimit()) {
    QuicConnectionPeer::SetAddressValidated(&connection_);
  }

  // Clear direct_peer_address.
  QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
  // Clear effective_peer_address, it is the same as direct_peer_address for
  // this test.
  QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                              QuicSocketAddress());
  EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

  RttStats* rtt_stats = const_cast<RttStats*>(manager_->GetRttStats());
  QuicTime::Delta default_init_rtt = rtt_stats->initial_rtt();
  rtt_stats->set_initial_rtt(default_init_rtt * 2);
  EXPECT_EQ(2 * default_init_rtt, rtt_stats->initial_rtt());

  QuicSentPacketManagerPeer::SetConsecutiveRtoCount(manager_, 1);
  EXPECT_EQ(1u, manager_->GetConsecutiveRtoCount());
  QuicSentPacketManagerPeer::SetConsecutiveTlpCount(manager_, 2);
  EXPECT_EQ(2u, manager_->GetConsecutiveTlpCount());

  const QuicSocketAddress kNewPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);
  EXPECT_CALL(visitor_, OnStreamFrame(_))
      .WillOnce(Invoke(
          [=]() { EXPECT_EQ(kPeerAddress, connection_.peer_address()); }))
      .WillOnce(Invoke(
          [=]() { EXPECT_EQ(kNewPeerAddress, connection_.peer_address()); }));
  QuicFrames frames;
  frames.push_back(QuicFrame(frame1_));
  ProcessFramesPacketWithAddresses(frames, kSelfAddress, kPeerAddress,
                                   ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

  // Process another packet with a different peer address on server side will
  // start connection migration.
  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);
  QuicFrames frames2;
  frames2.push_back(QuicFrame(frame2_));
  ProcessFramesPacketWithAddresses(frames2, kSelfAddress, kNewPeerAddress,
                                   ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
  // PORT_CHANGE shouldn't state change in sent packet manager.
  EXPECT_EQ(2 * default_init_rtt, rtt_stats->initial_rtt());
  EXPECT_EQ(1u, manager_->GetConsecutiveRtoCount());
  EXPECT_EQ(2u, manager_->GetConsecutiveTlpCount());
  EXPECT_EQ(manager_->GetSendAlgorithm(), send_algorithm_);
  if (connection_.validate_client_address()) {
    EXPECT_EQ(NO_CHANGE, connection_.active_effective_peer_migration_type());
    EXPECT_EQ(1u, connection_.GetStats().num_validated_peer_migration);
  }
}

TEST_P(QuicConnectionTest, PeerIpAddressChangeAtServer) {
  set_perspective(Perspective::IS_SERVER);
  if (!connection_.validate_client_address()) {
    return;
  }
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
  EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());
  connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
  // Discard INITIAL key.
  connection_.RemoveEncrypter(ENCRYPTION_INITIAL);
  connection_.NeuterUnencryptedPackets();
  // Prevent packets from being coalesced.
  EXPECT_CALL(visitor_, GetHandshakeState())
      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));
  QuicConnectionPeer::SetAddressValidated(&connection_);
  connection_.OnHandshakeComplete();

  // Enable 5 RTO
  QuicConfig config;
  QuicTagVector connection_options;
  connection_options.push_back(k5RTO);
  config.SetInitialReceivedConnectionOptions(connection_options);
  QuicConfigPeer::SetNegotiated(&config, true);
  QuicConfigPeer::SetReceivedOriginalConnectionId(&config,
                                                  connection_.connection_id());
  QuicConfigPeer::SetReceivedInitialSourceConnectionId(&config,
                                                       QuicConnectionId());
  EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
  connection_.SetFromConfig(config);

  // Clear direct_peer_address.
  QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
  // Clear effective_peer_address, it is the same as direct_peer_address for
  // this test.
  QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                              QuicSocketAddress());
  EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

  const QuicSocketAddress kNewPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback4(), /*port=*/23456);
  EXPECT_CALL(visitor_, OnStreamFrame(_))
      .WillOnce(Invoke(
          [=]() { EXPECT_EQ(kPeerAddress, connection_.peer_address()); }))
      .WillOnce(Invoke(
          [=]() { EXPECT_EQ(kNewPeerAddress, connection_.peer_address()); }));
  QuicFrames frames;
  frames.push_back(QuicFrame(frame1_));
  ProcessFramesPacketWithAddresses(frames, kSelfAddress, kPeerAddress,
                                   ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

  // Send some data to make connection has packets in flight.
  connection_.SendStreamData3();
  EXPECT_EQ(1u, writer_->packets_write_attempts());
  EXPECT_TRUE(connection_.BlackholeDetectionInProgress());
  EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

  // Process another packet with a different peer address on server side will
  // start connection migration.
  EXPECT_CALL(visitor_, OnConnectionMigration(IPV6_TO_IPV4_CHANGE)).Times(1);
  // IETF QUIC send algorithm should be changed to a different object, so no
  // OnPacketSent() called on the old send algorithm.
  EXPECT_CALL(*send_algorithm_,
              OnPacketSent(_, _, _, _, NO_RETRANSMITTABLE_DATA))
      .Times(0);
  // Do not propagate OnCanWrite() to session notifier.
  EXPECT_CALL(visitor_, OnCanWrite()).Times(AtLeast(1u));

  QuicFrames frames2;
  frames2.push_back(QuicFrame(frame2_));
  ProcessFramesPacketWithAddresses(frames2, kSelfAddress, kNewPeerAddress,
                                   ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
  EXPECT_EQ(IPV6_TO_IPV4_CHANGE,
            connection_.active_effective_peer_migration_type());
  EXPECT_FALSE(connection_.BlackholeDetectionInProgress());
  EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

  EXPECT_EQ(2u, writer_->packets_write_attempts());
  EXPECT_FALSE(writer_->path_challenge_frames().empty());
  QuicPathFrameBuffer payload =
      writer_->path_challenge_frames().front().data_buffer;
  EXPECT_NE(connection_.sent_packet_manager().GetSendAlgorithm(),
            send_algorithm_);
  // Switch to use the mock send algorithm.
  send_algorithm_ = new StrictMock<MockSendAlgorithm>();
  EXPECT_CALL(*send_algorithm_, CanSend(_)).WillRepeatedly(Return(true));
  EXPECT_CALL(*send_algorithm_, GetCongestionWindow())
      .WillRepeatedly(Return(kDefaultTCPMSS));
  EXPECT_CALL(*send_algorithm_, OnApplicationLimited(_)).Times(AnyNumber());
  EXPECT_CALL(*send_algorithm_, BandwidthEstimate())
      .Times(AnyNumber())
      .WillRepeatedly(Return(QuicBandwidth::Zero()));
  EXPECT_CALL(*send_algorithm_, InSlowStart()).Times(AnyNumber());
  EXPECT_CALL(*send_algorithm_, InRecovery()).Times(AnyNumber());
  EXPECT_CALL(*send_algorithm_, PopulateConnectionStats(_)).Times(AnyNumber());
  connection_.SetSendAlgorithm(send_algorithm_);

  // PATH_CHALLENGE is expanded upto the max packet size which may exceeds the
  // anti-amplification limit.
  EXPECT_EQ(kNewPeerAddress, writer_->last_write_peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
  EXPECT_EQ(1u,
            connection_.GetStats().num_reverse_path_validtion_upon_migration);

  // Verify server is throttled by anti-amplification limit.
  connection_.SendCryptoDataWithString("foo", 0);
  EXPECT_FALSE(connection_.GetRetransmissionAlarm()->IsSet());

  // Receiving an ACK to the packet sent after changing peer address doesn't
  // finish migration validation.
  QuicAckFrame ack_frame = InitAckFrame(2);
  EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _));
  ProcessFramePacketWithAddresses(QuicFrame(&ack_frame), kSelfAddress,
                                  kNewPeerAddress, ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
  EXPECT_EQ(IPV6_TO_IPV4_CHANGE,
            connection_.active_effective_peer_migration_type());

  // Receiving PATH_RESPONSE should lift the anti-amplification limit.
  QuicFrames frames3;
  frames3.push_back(QuicFrame(new QuicPathResponseFrame(99, payload)));
  EXPECT_CALL(visitor_, MaybeSendAddressToken());
  EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
      .Times(testing::AtLeast(1u));
  ProcessFramesPacketWithAddresses(frames3, kSelfAddress, kNewPeerAddress,
                                   ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(NO_CHANGE, connection_.active_effective_peer_migration_type());

  // Verify the anti-amplification limit is lifted by sending a packet larger
  // than the anti-amplification limit.
  connection_.SendCryptoDataWithString(std::string(1200, 'a'), 0);
  EXPECT_EQ(1u, connection_.GetStats().num_validated_peer_migration);
}

TEST_P(QuicConnectionTest, PeerIpAddressChangeAtServerWithMissingConnectionId) {
  set_perspective(Perspective::IS_SERVER);
  if (!connection_.connection_migration_use_new_cid()) {
    return;
  }
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
  EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());

  QuicConnectionId client_cid0 = TestConnectionId(1);
  QuicConnectionId client_cid1 = TestConnectionId(3);
  QuicConnectionId server_cid1;
  SetClientConnectionId(client_cid0);
  connection_.CreateConnectionIdManager();
  connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
  // Prevent packets from being coalesced.
  EXPECT_CALL(visitor_, GetHandshakeState())
      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));
  QuicConnectionPeer::SetAddressValidated(&connection_);

  // Sends new server CID to client.
  EXPECT_CALL(visitor_, OnServerConnectionIdIssued(_))
      .WillOnce(
          Invoke([&](const QuicConnectionId& cid) { server_cid1 = cid; }));
  EXPECT_CALL(visitor_, SendNewConnectionId(_));
  connection_.OnHandshakeComplete();

  // Clear direct_peer_address.
  QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
  // Clear effective_peer_address, it is the same as direct_peer_address for
  // this test.
  QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                              QuicSocketAddress());
  EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

  const QuicSocketAddress kNewPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback4(), /*port=*/23456);
  EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(2);
  QuicFrames frames;
  frames.push_back(QuicFrame(frame1_));
  ProcessFramesPacketWithAddresses(frames, kSelfAddress, kPeerAddress,
                                   ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

  // Send some data to make connection has packets in flight.
  connection_.SendStreamData3();
  EXPECT_EQ(1u, writer_->packets_write_attempts());

  // Process another packet with a different peer address on server side will
  // start connection migration.
  peer_creator_.SetServerConnectionId(server_cid1);
  EXPECT_CALL(visitor_, OnConnectionMigration(IPV6_TO_IPV4_CHANGE)).Times(1);
  // Do not propagate OnCanWrite() to session notifier.
  EXPECT_CALL(visitor_, OnCanWrite()).Times(AtLeast(1u));

  QuicFrames frames2;
  frames2.push_back(QuicFrame(frame2_));
  ProcessFramesPacketWithAddresses(frames2, kSelfAddress, kNewPeerAddress,
                                   ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());

  // Writing path response & reverse path challenge is blocked due to missing
  // client connection ID, i.e., packets_write_attempts is unchanged.
  EXPECT_EQ(1u, writer_->packets_write_attempts());

  // Receives new client CID from client would unblock write.
  QuicNewConnectionIdFrame new_cid_frame;
  new_cid_frame.connection_id = client_cid1;
  new_cid_frame.sequence_number = 1u;
  new_cid_frame.retire_prior_to = 0u;
  connection_.OnNewConnectionIdFrame(new_cid_frame);
  connection_.SendStreamData3();

  EXPECT_EQ(2u, writer_->packets_write_attempts());
}

TEST_P(QuicConnectionTest, EffectivePeerAddressChangeAtServer) {
  set_perspective(Perspective::IS_SERVER);
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
  EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());
  if (version().SupportsAntiAmplificationLimit()) {
    QuicConnectionPeer::SetAddressValidated(&connection_);
  }
  connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
  // Discard INITIAL key.
  connection_.RemoveEncrypter(ENCRYPTION_INITIAL);
  connection_.NeuterUnencryptedPackets();
  EXPECT_CALL(visitor_, GetHandshakeState())
      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));

  // Clear direct_peer_address.
  QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
  // Clear effective_peer_address, it is different from direct_peer_address for
  // this test.
  QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                              QuicSocketAddress());
  const QuicSocketAddress kEffectivePeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/43210);
  connection_.ReturnEffectivePeerAddressForNextPacket(kEffectivePeerAddress);

  if (QuicVersionUsesCryptoFrames(connection_.transport_version())) {
    EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
  } else {
    EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
  }
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress, kPeerAddress,
                                  ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kEffectivePeerAddress, connection_.effective_peer_address());

  // Process another packet with the same direct peer address and different
  // effective peer address on server side will start connection migration.
  const QuicSocketAddress kNewEffectivePeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/54321);
  connection_.ReturnEffectivePeerAddressForNextPacket(kNewEffectivePeerAddress);
  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress, kPeerAddress,
                                  ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewEffectivePeerAddress, connection_.effective_peer_address());
  EXPECT_EQ(kPeerAddress, writer_->last_write_peer_address());
  if (connection_.validate_client_address()) {
    EXPECT_EQ(NO_CHANGE, connection_.active_effective_peer_migration_type());
    EXPECT_EQ(1u, connection_.GetStats().num_validated_peer_migration);
  }

  // Process another packet with a different direct peer address and the same
  // effective peer address on server side will not start connection migration.
  const QuicSocketAddress kNewPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);
  connection_.ReturnEffectivePeerAddressForNextPacket(kNewEffectivePeerAddress);
  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);

  if (!connection_.validate_client_address()) {
    // ack_frame is used to complete the migration started by the last packet,
    // we need to make sure a new migration does not start after the previous
    // one is completed.
    QuicAckFrame ack_frame = InitAckFrame(1);
    EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _));
    ProcessFramePacketWithAddresses(QuicFrame(&ack_frame), kSelfAddress,
                                    kNewPeerAddress, ENCRYPTION_FORWARD_SECURE);
    EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
    EXPECT_EQ(kNewEffectivePeerAddress, connection_.effective_peer_address());
    EXPECT_EQ(NO_CHANGE, connection_.active_effective_peer_migration_type());
  }

  // Process another packet with different direct peer address and different
  // effective peer address on server side will start connection migration.
  const QuicSocketAddress kNewerEffectivePeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/65432);
  const QuicSocketAddress kFinalPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/34567);
  connection_.ReturnEffectivePeerAddressForNextPacket(
      kNewerEffectivePeerAddress);
  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress,
                                  kFinalPeerAddress, ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kFinalPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewerEffectivePeerAddress, connection_.effective_peer_address());
  if (connection_.validate_client_address()) {
    EXPECT_EQ(NO_CHANGE, connection_.active_effective_peer_migration_type());
    EXPECT_EQ(send_algorithm_,
              connection_.sent_packet_manager().GetSendAlgorithm());
    EXPECT_EQ(2u, connection_.GetStats().num_validated_peer_migration);
  }

  // While the previous migration is ongoing, process another packet with the
  // same direct peer address and different effective peer address on server
  // side will start a new connection migration.
  const QuicSocketAddress kNewestEffectivePeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback4(), /*port=*/65430);
  connection_.ReturnEffectivePeerAddressForNextPacket(
      kNewestEffectivePeerAddress);
  EXPECT_CALL(visitor_, OnConnectionMigration(IPV6_TO_IPV4_CHANGE)).Times(1);
  if (!connection_.validate_client_address()) {
    EXPECT_CALL(*send_algorithm_, OnConnectionMigration()).Times(1);
  }
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress,
                                  kFinalPeerAddress, ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kFinalPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewestEffectivePeerAddress, connection_.effective_peer_address());
  EXPECT_EQ(IPV6_TO_IPV4_CHANGE,
            connection_.active_effective_peer_migration_type());
  if (connection_.validate_client_address()) {
    EXPECT_NE(send_algorithm_,
              connection_.sent_packet_manager().GetSendAlgorithm());
    EXPECT_EQ(kFinalPeerAddress, writer_->last_write_peer_address());
    EXPECT_FALSE(writer_->path_challenge_frames().empty());
    EXPECT_EQ(0u, connection_.GetStats()
                      .num_peer_migration_while_validating_default_path);
    EXPECT_TRUE(connection_.HasPendingPathValidation());
  }
}

// Regression test for b/200020764.
TEST_P(QuicConnectionTest, ConnectionMigrationWithPendingPaddingBytes) {
  // TODO(haoyuewang) Move these test setup code to a common member function.
  set_perspective(Perspective::IS_SERVER);
  if (!connection_.connection_migration_use_new_cid()) {
    return;
  }
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
  connection_.CreateConnectionIdManager();
  connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
  QuicConnectionPeer::SetPeerAddress(&connection_, kPeerAddress);
  QuicConnectionPeer::SetEffectivePeerAddress(&connection_, kPeerAddress);
  QuicConnectionPeer::SetAddressValidated(&connection_);

  // Sends new server CID to client.
  QuicConnectionId new_cid;
  EXPECT_CALL(visitor_, OnServerConnectionIdIssued(_))
      .WillOnce(Invoke([&](const QuicConnectionId& cid) { new_cid = cid; }));
  EXPECT_CALL(visitor_, SendNewConnectionId(_));
  // Discard INITIAL key.
  connection_.RemoveEncrypter(ENCRYPTION_INITIAL);
  connection_.NeuterUnencryptedPackets();
  connection_.OnHandshakeComplete();
  EXPECT_CALL(visitor_, GetHandshakeState())
      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));

  auto* packet_creator = QuicConnectionPeer::GetPacketCreator(&connection_);
  packet_creator->FlushCurrentPacket();
  packet_creator->AddPendingPadding(50u);
  const QuicSocketAddress kPeerAddress3 =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/56789);
  auto ack_frame = InitAckFrame(1);
  EXPECT_CALL(*send_algorithm_, OnCongestionEvent(_, _, _, _, _));
  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);
  ProcessFramesPacketWithAddresses({QuicFrame(&ack_frame)}, kSelfAddress,
                                   kPeerAddress3, ENCRYPTION_FORWARD_SECURE);
  if (GetQuicReloadableFlag(
          quic_flush_pending_frames_and_padding_bytes_on_migration)) {
    // Any pending frames/padding should be flushed before default_path_ is
    // temporarily reset.
    ASSERT_EQ(connection_.self_address_on_default_path_while_sending_packet()
                  .host()
                  .address_family(),
              IpAddressFamily::IP_V6);
  } else {
    ASSERT_EQ(connection_.self_address_on_default_path_while_sending_packet()
                  .host()
                  .address_family(),
              IpAddressFamily::IP_UNSPEC);
  }
}

// Regression test for b/196208556.
TEST_P(QuicConnectionTest,
       ReversePathValidationResponseReceivedFromUnexpectedPeerAddress) {
  set_perspective(Perspective::IS_SERVER);
  if (!connection_.connection_migration_use_new_cid()) {
    return;
  }
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
  connection_.CreateConnectionIdManager();
  connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
  QuicConnectionPeer::SetPeerAddress(&connection_, kPeerAddress);
  QuicConnectionPeer::SetEffectivePeerAddress(&connection_, kPeerAddress);
  QuicConnectionPeer::SetAddressValidated(&connection_);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

  // Sends new server CID to client.
  QuicConnectionId new_cid;
  EXPECT_CALL(visitor_, OnServerConnectionIdIssued(_))
      .WillOnce(Invoke([&](const QuicConnectionId& cid) { new_cid = cid; }));
  EXPECT_CALL(visitor_, SendNewConnectionId(_));
  // Discard INITIAL key.
  connection_.RemoveEncrypter(ENCRYPTION_INITIAL);
  connection_.NeuterUnencryptedPackets();
  connection_.OnHandshakeComplete();
  EXPECT_CALL(visitor_, GetHandshakeState())
      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));

  // Process a non-probing packet to migrate to path 2 and kick off reverse path
  // validation.
  EXPECT_CALL(visitor_, OnConnectionMigration(IPV6_TO_IPV4_CHANGE)).Times(1);
  const QuicSocketAddress kPeerAddress2 =
      QuicSocketAddress(QuicIpAddress::Loopback4(), /*port=*/23456);
  peer_creator_.SetServerConnectionId(new_cid);
  ProcessFramesPacketWithAddresses({QuicFrame(QuicPingFrame())}, kSelfAddress,
                                   kPeerAddress2, ENCRYPTION_FORWARD_SECURE);
  EXPECT_FALSE(writer_->path_challenge_frames().empty());
  QuicPathFrameBuffer reverse_path_challenge_payload =
      writer_->path_challenge_frames().front().data_buffer;

  // Receiveds a packet from path 3 with PATH_RESPONSE frame intended to
  // validate path 2 and a non-probing frame.
  {
    QuicConnection::ScopedPacketFlusher flusher(&connection_);
    const QuicSocketAddress kPeerAddress3 =
        QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/56789);
    auto ack_frame = InitAckFrame(1);
    EXPECT_CALL(visitor_, OnConnectionMigration(IPV4_TO_IPV6_CHANGE)).Times(1);
    EXPECT_CALL(visitor_, MaybeSendAddressToken()).WillOnce(Invoke([this]() {
      connection_.SendControlFrame(
          QuicFrame(new QuicNewTokenFrame(1, "new_token")));
      return true;
    }));
    ProcessFramesPacketWithAddresses({QuicFrame(new QuicPathResponseFrame(
                                          0, reverse_path_challenge_payload)),
                                      QuicFrame(&ack_frame)},
                                     kSelfAddress, kPeerAddress3,
                                     ENCRYPTION_FORWARD_SECURE);
  }
}

TEST_P(QuicConnectionTest, ReversePathValidationFailureAtServer) {
  set_perspective(Perspective::IS_SERVER);
  if (!connection_.connection_migration_use_new_cid()) {
    return;
  }
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
  EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());
  SetClientConnectionId(TestConnectionId(1));
  connection_.CreateConnectionIdManager();
  connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
  // Discard INITIAL key.
  connection_.RemoveEncrypter(ENCRYPTION_INITIAL);
  connection_.NeuterUnencryptedPackets();
  // Prevent packets from being coalesced.
  EXPECT_CALL(visitor_, GetHandshakeState())
      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));
  QuicConnectionPeer::SetAddressValidated(&connection_);

  QuicConnectionId client_cid0 = connection_.client_connection_id();
  QuicConnectionId client_cid1 = TestConnectionId(2);
  QuicConnectionId server_cid0 = connection_.connection_id();
  QuicConnectionId server_cid1;
  // Sends new server CID to client.
  EXPECT_CALL(visitor_, OnServerConnectionIdIssued(_))
      .WillOnce(
          Invoke([&](const QuicConnectionId& cid) { server_cid1 = cid; }));
  EXPECT_CALL(visitor_, SendNewConnectionId(_));
  connection_.OnHandshakeComplete();
  // Receives new client CID from client.
  QuicNewConnectionIdFrame new_cid_frame;
  new_cid_frame.connection_id = client_cid1;
  new_cid_frame.sequence_number = 1u;
  new_cid_frame.retire_prior_to = 0u;
  connection_.OnNewConnectionIdFrame(new_cid_frame);
  auto* packet_creator = QuicConnectionPeer::GetPacketCreator(&connection_);
  ASSERT_EQ(packet_creator->GetDestinationConnectionId(), client_cid0);
  ASSERT_EQ(packet_creator->GetSourceConnectionId(), server_cid0);

  // Clear direct_peer_address.
  QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
  // Clear effective_peer_address, it is the same as direct_peer_address for
  // this test.
  QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                              QuicSocketAddress());
  EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

  const QuicSocketAddress kNewPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback4(), /*port=*/23456);
  EXPECT_CALL(visitor_, OnStreamFrame(_))
      .WillOnce(Invoke(
          [=]() { EXPECT_EQ(kPeerAddress, connection_.peer_address()); }))
      .WillOnce(Invoke(
          [=]() { EXPECT_EQ(kNewPeerAddress, connection_.peer_address()); }));
  QuicFrames frames;
  frames.push_back(QuicFrame(frame1_));
  ProcessFramesPacketWithAddresses(frames, kSelfAddress, kPeerAddress,
                                   ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

  // Process another packet with a different peer address on server side will
  // start connection migration.
  EXPECT_CALL(visitor_, OnConnectionMigration(IPV6_TO_IPV4_CHANGE)).Times(1);
  // IETF QUIC send algorithm should be changed to a different object, so no
  // OnPacketSent() called on the old send algorithm.
  EXPECT_CALL(*send_algorithm_, OnConnectionMigration()).Times(0);

  QuicFrames frames2;
  frames2.push_back(QuicFrame(frame2_));
  QuicPaddingFrame padding;
  frames2.push_back(QuicFrame(padding));
  peer_creator_.SetServerConnectionId(server_cid1);
  ProcessFramesPacketWithAddresses(frames2, kSelfAddress, kNewPeerAddress,
                                   ENCRYPTION_FORWARD_SECURE);
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
  EXPECT_EQ(IPV6_TO_IPV4_CHANGE,
            connection_.active_effective_peer_migration_type());
  EXPECT_LT(0u, writer_->packets_write_attempts());
  EXPECT_TRUE(connection_.HasPendingPathValidation());
  EXPECT_NE(connection_.sent_packet_manager().GetSendAlgorithm(),
            send_algorithm_);
  EXPECT_EQ(kNewPeerAddress, writer_->last_write_peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
  const auto* default_path = QuicConnectionPeer::GetDefaultPath(&connection_);
  const auto* alternative_path =
      QuicConnectionPeer::GetAlternativePath(&connection_);
  EXPECT_EQ(default_path->client_connection_id, client_cid1);
  EXPECT_EQ(default_path->server_connection_id, server_cid1);
  EXPECT_EQ(alternative_path->client_connection_id, client_cid0);
  EXPECT_EQ(alternative_path->server_connection_id, server_cid0);
  EXPECT_EQ(packet_creator->GetDestinationConnectionId(), client_cid1);
  EXPECT_EQ(packet_creator->GetSourceConnectionId(), server_cid1);

  for (size_t i = 0; i < QuicPathValidator::kMaxRetryTimes; ++i) {
    clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(3 * kInitialRttMs));
    static_cast<TestAlarmFactory::TestAlarm*>(
        QuicPathValidatorPeer::retry_timer(
            QuicConnectionPeer::path_validator(&connection_)))
        ->Fire();
  }
  EXPECT_EQ(IPV6_TO_IPV4_CHANGE,
            connection_.active_effective_peer_migration_type());

  // Make sure anti-amplification limit is not reached.
  ProcessFramesPacketWithAddresses(
      {QuicFrame(QuicPingFrame()), QuicFrame(QuicPaddingFrame())}, kSelfAddress,
      kNewPeerAddress, ENCRYPTION_FORWARD_SECURE);
  SendStreamDataToPeer(1, "foo", 0, NO_FIN, nullptr);
  EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

  // Advance the time so that the reverse path validation times out.
  clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(3 * kInitialRttMs));
  static_cast<TestAlarmFactory::TestAlarm*>(
      QuicPathValidatorPeer::retry_timer(
          QuicConnectionPeer::path_validator(&connection_)))
      ->Fire();
  EXPECT_EQ(NO_CHANGE, connection_.active_effective_peer_migration_type());
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
  EXPECT_EQ(connection_.sent_packet_manager().GetSendAlgorithm(),
            send_algorithm_);
  EXPECT_TRUE(connection_.GetRetransmissionAlarm()->IsSet());

  // Verify that default_path_ is reverted and alternative_path_ is cleared.
  EXPECT_EQ(default_path->client_connection_id, client_cid0);
  EXPECT_EQ(default_path->server_connection_id, server_cid0);
  EXPECT_TRUE(alternative_path->server_connection_id.IsEmpty());
  EXPECT_FALSE(alternative_path->stateless_reset_token.has_value());
  auto* retire_peer_issued_cid_alarm =
      connection_.GetRetirePeerIssuedConnectionIdAlarm();
  ASSERT_TRUE(retire_peer_issued_cid_alarm->IsSet());
  EXPECT_CALL(visitor_, SendRetireConnectionId(/*sequence_number=*/1u));
  retire_peer_issued_cid_alarm->Fire();
  EXPECT_EQ(packet_creator->GetDestinationConnectionId(), client_cid0);
  EXPECT_EQ(packet_creator->GetSourceConnectionId(), server_cid0);
}

TEST_P(QuicConnectionTest, ReceivePathProbeWithNoAddressChangeAtServer) {
  PathProbeTestInit(Perspective::IS_SERVER);

  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
  EXPECT_CALL(visitor_, OnPacketReceived(_, _, false)).Times(0);

  // Process a padded PING packet with no peer address change on server side
  // will be ignored. But a PATH CHALLENGE packet with no peer address change
  // will be considered as path probing.
  std::unique_ptr<SerializedPacket> probing_packet = ConstructProbingPacket();

  std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
      QuicEncryptedPacket(probing_packet->encrypted_buffer,
                          probing_packet->encrypted_length),
      clock_.Now()));

  uint64_t num_probing_received =
      connection_.GetStats().num_connectivity_probing_received;
  ProcessReceivedPacket(kSelfAddress, kPeerAddress, *received);

  EXPECT_EQ(num_probing_received + (GetParam().version.HasIetfQuicFrames() &&
                                            connection_.send_path_response()
                                        ? 1u
                                        : 0u),
            connection_.GetStats().num_connectivity_probing_received);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
}

// Regression test for b/150161358.
TEST_P(QuicConnectionTest, BufferedMtuPacketTooBig) {
  EXPECT_CALL(visitor_, OnWriteBlocked()).Times(1);
  writer_->SetWriteBlocked();

  // Send a MTU packet while blocked. It should be buffered.
  connection_.SendMtuDiscoveryPacket(kMaxOutgoingPacketSize);
  EXPECT_EQ(1u, connection_.NumQueuedPackets());
  EXPECT_TRUE(writer_->IsWriteBlocked());

  writer_->AlwaysGetPacketTooLarge();
  writer_->SetWritable();
  connection_.OnCanWrite();
}

TEST_P(QuicConnectionTest, WriteOutOfOrderQueuedPackets) {
  // EXPECT_QUIC_BUG tests are expensive so only run one instance of them.
  if (!IsDefaultTestConfiguration()) {
    return;
  }

  set_perspective(Perspective::IS_CLIENT);

  BlockOnNextWrite();

  QuicStreamId stream_id = 2;
  connection_.SendStreamDataWithString(stream_id, "foo", 0, NO_FIN);

  EXPECT_EQ(1u, connection_.NumQueuedPackets());

  writer_->SetWritable();
  connection_.SendConnectivityProbingPacket(writer_.get(),
                                            connection_.peer_address());
  EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(0);
  connection_.OnCanWrite();
}

TEST_P(QuicConnectionTest, DiscardQueuedPacketsAfterConnectionClose) {
  // Regression test for b/74073386.
  {
    InSequence seq;
    EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
        .Times(AtLeast(1));
    EXPECT_CALL(visitor_, OnConnectionClosed(_, _)).Times(AtLeast(1));
  }

  set_perspective(Perspective::IS_CLIENT);

  writer_->SimulateNextPacketTooLarge();

  // This packet write should fail, which should cause the connection to close
  // after sending a connection close packet, then the failed packet should be
  // queued.
  connection_.SendStreamDataWithString(/*id=*/2, "foo", 0, NO_FIN);

  EXPECT_FALSE(connection_.connected());
  // No need to buffer packets.
  EXPECT_EQ(0u, connection_.NumQueuedPackets());

  EXPECT_EQ(0u, connection_.GetStats().packets_discarded);
  connection_.OnCanWrite();
  EXPECT_EQ(0u, connection_.GetStats().packets_discarded);
}

class TestQuicPathValidationContext : public QuicPathValidationContext {
 public:
  TestQuicPathValidationContext(const QuicSocketAddress& self_address,
                                const QuicSocketAddress& peer_address,

                                QuicPacketWriter* writer)
      : QuicPathValidationContext(self_address, peer_address),
        writer_(writer) {}

  QuicPacketWriter* WriterToUse() override { return writer_; }

 private:
  QuicPacketWriter* writer_;
};

class TestValidationResultDelegate : public QuicPathValidator::ResultDelegate {
 public:
  TestValidationResultDelegate(QuicConnection* connection,
                               const QuicSocketAddress& expected_self_address,
                               const QuicSocketAddress& expected_peer_address,
                               bool* success)
      : QuicPathValidator::ResultDelegate(),
        connection_(connection),
        expected_self_address_(expected_self_address),
        expected_peer_address_(expected_peer_address),
        success_(success) {}
  void OnPathValidationSuccess(
      std::unique_ptr<QuicPathValidationContext> context) override {
    EXPECT_EQ(expected_self_address_, context->self_address());
    EXPECT_EQ(expected_peer_address_, context->peer_address());
    *success_ = true;
  }

  void OnPathValidationFailure(
      std::unique_ptr<QuicPathValidationContext> context) override {
    EXPECT_EQ(expected_self_address_, context->self_address());
    EXPECT_EQ(expected_peer_address_, context->peer_address());
    if (connection_->perspective() == Perspective::IS_CLIENT) {
      connection_->OnPathValidationFailureAtClient();
    }
    *success_ = false;
  }

 private:
  QuicConnection* connection_;
  QuicSocketAddress expected_self_address_;
  QuicSocketAddress expected_peer_address_;
  bool* success_;
};

// Receive a path probe request at the server side, i.e.,
// in non-IETF version: receive a padded PING packet with a peer addess change;
// in IETF version: receive a packet contains PATH CHALLENGE with peer address
// change.
TEST_P(QuicConnectionTest, ReceivePathProbingAtServer) {
  PathProbeTestInit(Perspective::IS_SERVER);

  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
  QuicPathFrameBuffer payload;
  if (!GetParam().version.HasIetfQuicFrames()) {
    EXPECT_CALL(visitor_,
                OnPacketReceived(_, _, /*is_connectivity_probe=*/true))
        .Times(1);
  } else {
    EXPECT_CALL(visitor_, OnPacketReceived(_, _, _)).Times(0);
    if (connection_.validate_client_address()) {
      EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
          .Times(AtLeast(1u))
          .WillOnce(Invoke([&]() {
            EXPECT_EQ(1u, writer_->path_challenge_frames().size());
            EXPECT_EQ(1u, writer_->path_response_frames().size());
            payload = writer_->path_challenge_frames().front().data_buffer;
          }));
    }
  }
  // Process a probing packet from a new peer address on server side
  // is effectively receiving a connectivity probing.
  const QuicSocketAddress kNewPeerAddress(QuicIpAddress::Loopback4(),
                                          /*port=*/23456);

  std::unique_ptr<SerializedPacket> probing_packet = ConstructProbingPacket();
  std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
      QuicEncryptedPacket(probing_packet->encrypted_buffer,
                          probing_packet->encrypted_length),
      clock_.Now()));
  uint64_t num_probing_received =
      connection_.GetStats().num_connectivity_probing_received;
  ProcessReceivedPacket(kSelfAddress, kNewPeerAddress, *received);

  EXPECT_EQ(num_probing_received + 1,
            connection_.GetStats().num_connectivity_probing_received);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
  if (GetParam().version.HasIetfQuicFrames() &&
      connection_.use_path_validator() &&
      GetQuicReloadableFlag(quic_count_bytes_on_alternative_path_seperately)) {
    QuicByteCount bytes_sent =
        QuicConnectionPeer::BytesSentOnAlternativePath(&connection_);
    EXPECT_LT(0u, bytes_sent);
    EXPECT_EQ(received->length(),
              QuicConnectionPeer::BytesReceivedOnAlternativePath(&connection_));

    // Receiving one more probing packet should update the bytes count.
    probing_packet = ConstructProbingPacket();
    received.reset(ConstructReceivedPacket(
        QuicEncryptedPacket(probing_packet->encrypted_buffer,
                            probing_packet->encrypted_length),
        clock_.Now()));
    ProcessReceivedPacket(kSelfAddress, kNewPeerAddress, *received);

    EXPECT_EQ(num_probing_received + 2,
              connection_.GetStats().num_connectivity_probing_received);
    EXPECT_EQ(2 * bytes_sent,
              QuicConnectionPeer::BytesSentOnAlternativePath(&connection_));
    EXPECT_EQ(2 * received->length(),
              QuicConnectionPeer::BytesReceivedOnAlternativePath(&connection_));

    bool success = false;
    if (!connection_.validate_client_address()) {
      EXPECT_CALL(*send_algorithm_, OnPacketSent(_, _, _, _, _))
          .Times(AtLeast(1u))
          .WillOnce(Invoke([&]() {
            EXPECT_EQ(1u, writer_->path_challenge_frames().size());
            payload = writer_->path_challenge_frames().front().data_buffer;
          }));

      connection_.ValidatePath(
          std::make_unique<TestQuicPathValidationContext>(
              connection_.self_address(), kNewPeerAddress, writer_.get()),
          std::make_unique<TestValidationResultDelegate>(
              &connection_, connection_.self_address(), kNewPeerAddress,
              &success));
    }
    EXPECT_EQ((connection_.validate_client_address() ? 2 : 3) * bytes_sent,
              QuicConnectionPeer::BytesSentOnAlternativePath(&connection_));
    QuicFrames frames;
    frames.push_back(QuicFrame(new QuicPathResponseFrame(99, payload)));
    ProcessFramesPacketWithAddresses(frames, connection_.self_address(),
                                     kNewPeerAddress,
                                     ENCRYPTION_FORWARD_SECURE);
    EXPECT_LT(2 * received->length(),
              QuicConnectionPeer::BytesReceivedOnAlternativePath(&connection_));
    if (connection_.validate_client_address()) {
      EXPECT_TRUE(QuicConnectionPeer::IsAlternativePathValidated(&connection_));
    }
    // Receiving another probing packet from a newer address with a different
    // port shouldn't trigger another reverse path validation.
    QuicSocketAddress kNewerPeerAddress(QuicIpAddress::Loopback4(),
                                        /*port=*/34567);
    probing_packet = ConstructProbingPacket();
    received.reset(ConstructReceivedPacket(
        QuicEncryptedPacket(probing_packet->encrypted_buffer,
                            probing_packet->encrypted_length),
        clock_.Now()));
    ProcessReceivedPacket(kSelfAddress, kNewerPeerAddress, *received);
    EXPECT_FALSE(connection_.HasPendingPathValidation());
    EXPECT_EQ(connection_.validate_client_address(),
              QuicConnectionPeer::IsAlternativePathValidated(&connection_));
  }

  // Process another packet with the old peer address on server side will not
  // start peer migration.
  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress, kPeerAddress,
                                  ENCRYPTION_INITIAL);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
}

// Receive a padded PING packet with a port change on server side.
TEST_P(QuicConnectionTest, ReceivePaddedPingWithPortChangeAtServer) {
  set_perspective(Perspective::IS_SERVER);
  QuicPacketCreatorPeer::SetSendVersionInPacket(creator_, false);
  EXPECT_EQ(Perspective::IS_SERVER, connection_.perspective());
  if (version().SupportsAntiAmplificationLimit()) {
    QuicConnectionPeer::SetAddressValidated(&connection_);
  }

  // Clear direct_peer_address.
  QuicConnectionPeer::SetDirectPeerAddress(&connection_, QuicSocketAddress());
  // Clear effective_peer_address, it is the same as direct_peer_address for
  // this test.
  QuicConnectionPeer::SetEffectivePeerAddress(&connection_,
                                              QuicSocketAddress());
  EXPECT_FALSE(connection_.effective_peer_address().IsInitialized());

  if (GetParam().version.UsesCryptoFrames()) {
    EXPECT_CALL(visitor_, OnCryptoFrame(_)).Times(AnyNumber());
  } else {
    EXPECT_CALL(visitor_, OnStreamFrame(_)).Times(AnyNumber());
  }
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress, kPeerAddress,
                                  ENCRYPTION_INITIAL);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

  if (GetParam().version.HasIetfQuicFrames()) {
    // In IETF version, a padded PING packet with port change is not taken as
    // connectivity probe.
    EXPECT_CALL(visitor_, GetHandshakeState())
        .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));
    EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);
    EXPECT_CALL(visitor_, OnPacketReceived(_, _, _)).Times(0);
  } else {
    // In non-IETF version, process a padded PING packet from a new peer
    // address on server side is effectively receiving a connectivity probing.
    EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
    EXPECT_CALL(visitor_,
                OnPacketReceived(_, _, /*is_connectivity_probe=*/true))
        .Times(1);
  }
  const QuicSocketAddress kNewPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);

  QuicFrames frames;
  // Write a PING frame, which has no data payload.
  QuicPingFrame ping_frame;
  frames.push_back(QuicFrame(ping_frame));

  // Add padding to the rest of the packet.
  QuicPaddingFrame padding_frame;
  frames.push_back(QuicFrame(padding_frame));

  uint64_t num_probing_received =
      connection_.GetStats().num_connectivity_probing_received;

  ProcessFramesPacketWithAddresses(frames, kSelfAddress, kNewPeerAddress,
                                   ENCRYPTION_INITIAL);

  if (GetParam().version.HasIetfQuicFrames()) {
    // Padded PING with port changen is not considered as connectivity probe but
    // a PORT CHANGE.
    EXPECT_EQ(num_probing_received,
              connection_.GetStats().num_connectivity_probing_received);
    EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
    EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
  } else {
    EXPECT_EQ(num_probing_received + 1,
              connection_.GetStats().num_connectivity_probing_received);
    EXPECT_EQ(kPeerAddress, connection_.peer_address());
    EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
  }

  if (GetParam().version.HasIetfQuicFrames()) {
    EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);
  }
  // Process another packet with the old peer address on server side. gQUIC
  // shouldn't regard this as a peer migration.
  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress, kPeerAddress,
                                  ENCRYPTION_INITIAL);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
}

TEST_P(QuicConnectionTest, ReceiveReorderedPathProbingAtServer) {
  PathProbeTestInit(Perspective::IS_SERVER);

  // Decrease packet number to simulate out-of-order packets.
  QuicPacketCreatorPeer::SetPacketNumber(&peer_creator_, 4);

  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
  if (!GetParam().version.HasIetfQuicFrames()) {
    EXPECT_CALL(visitor_,
                OnPacketReceived(_, _, /*is_connectivity_probe=*/true))
        .Times(1);
  } else {
    EXPECT_CALL(visitor_, OnPacketReceived(_, _, _)).Times(0);
  }

  // Process a padded PING packet from a new peer address on server side
  // is effectively receiving a connectivity probing, even if a newer packet has
  // been received before this one.
  const QuicSocketAddress kNewPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);

  std::unique_ptr<SerializedPacket> probing_packet = ConstructProbingPacket();
  std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
      QuicEncryptedPacket(probing_packet->encrypted_buffer,
                          probing_packet->encrypted_length),
      clock_.Now()));

  uint64_t num_probing_received =
      connection_.GetStats().num_connectivity_probing_received;
  ProcessReceivedPacket(kSelfAddress, kNewPeerAddress, *received);

  EXPECT_EQ(num_probing_received + 1,
            connection_.GetStats().num_connectivity_probing_received);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
}

TEST_P(QuicConnectionTest, MigrateAfterProbingAtServer) {
  PathProbeTestInit(Perspective::IS_SERVER);

  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
  if (!GetParam().version.HasIetfQuicFrames()) {
    EXPECT_CALL(visitor_,
                OnPacketReceived(_, _, /*is_connectivity_probe=*/true))
        .Times(1);
  } else {
    EXPECT_CALL(visitor_, OnPacketReceived(_, _, _)).Times(0);
  }

  // Process a padded PING packet from a new peer address on server side
  // is effectively receiving a connectivity probing.
  const QuicSocketAddress kNewPeerAddress =
      QuicSocketAddress(QuicIpAddress::Loopback6(), /*port=*/23456);

  std::unique_ptr<SerializedPacket> probing_packet = ConstructProbingPacket();
  std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
      QuicEncryptedPacket(probing_packet->encrypted_buffer,
                          probing_packet->encrypted_length),
      clock_.Now()));
  ProcessReceivedPacket(kSelfAddress, kNewPeerAddress, *received);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());

  // Process another non-probing packet with the new peer address on server
  // side will start peer migration.
  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(1);

  ProcessFramePacketWithAddresses(MakeCryptoFrame(), kSelfAddress,
                                  kNewPeerAddress, ENCRYPTION_INITIAL);
  EXPECT_EQ(kNewPeerAddress, connection_.peer_address());
  EXPECT_EQ(kNewPeerAddress, connection_.effective_peer_address());
}

TEST_P(QuicConnectionTest, ReceiveConnectivityProbingPacketAtClient) {
  EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));
  PathProbeTestInit(Perspective::IS_CLIENT);

  // Client takes all padded PING packet as speculative connectivity
  // probing packet, and reports to visitor.
  EXPECT_CALL(visitor_, OnConnectionMigration(PORT_CHANGE)).Times(0);
  if (!connection_.send_path_response()) {
    EXPECT_CALL(visitor_, OnPacketReceived(_, _, false)).Times(1);
  }

  std::unique_ptr<SerializedPacket> probing_packet = ConstructProbingPacket();
  std::unique_ptr<QuicReceivedPacket> received(ConstructReceivedPacket(
      QuicEncryptedPacket(probing_packet->encrypted_buffer,
                          probing_packet->encrypted_length),
      clock_.Now()));
  uint64_t num_probing_received =
      connection_.GetStats().num_connectivity_probing_received;
  ProcessReceivedPacket(kSelfAddress, kPeerAddress, *received);

  EXPECT_EQ(num_probing_received + (GetParam().version.HasIetfQuicFrames() &&
                                            connection_.send_path_response()
                                        ? 1u
                                        : 0u),
            connection_.GetStats().num_connectivity_probing_received);
  EXPECT_EQ(kPeerAddress, connection_.peer_address());
  EXPECT_EQ(kPeerAddress, connection_.effective_peer_address());
}

TEST_P(QuicConnectionTest, ReceiveConnectivityProbingResponseAtClient) {
  // TODO(b/150095484): add test coverage for IETF to verify that client takes
  // PATH RESPONSE with peer address change as correct validation on the new
  // path.
  if (GetParam().version.HasIetfQuicFrames()) {
    return;
  }
  EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_));