net/quic/quic_connection.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/quic/quic_connection.h"
   6
   7 #include <string.h>
   8 #include <sys/types.h>
   9
  10 #include <algorithm>
  11 #include <iterator>
  12 #include <limits>
  13 #include <memory>
  14 #include <set>
  15 #include <utility>
  16
  17 #include "base/debug/stack_trace.h"
  18 #include "base/format_macros.h"
  19 #include "base/logging.h"
  20 #include "base/profiler/scoped_tracker.h"
  21 #include "base/stl_util.h"
  22 #include "base/strings/stringprintf.h"
  23 #include "net/base/net_errors.h"
  24 #include "net/quic/crypto/crypto_protocol.h"
  25 #include "net/quic/crypto/quic_decrypter.h"
  26 #include "net/quic/crypto/quic_encrypter.h"
  27 #include "net/quic/proto/cached_network_parameters.pb.h"
  28 #include "net/quic/quic_bandwidth.h"
  29 #include "net/quic/quic_config.h"
  30 #include "net/quic/quic_fec_group.h"
  31 #include "net/quic/quic_flags.h"
  32 #include "net/quic/quic_packet_generator.h"
  33 #include "net/quic/quic_utils.h"
  34
  35 using base::StringPiece;
  36 using base::StringPrintf;
  37 using base::hash_map;
  38 using base::hash_set;
  39 using std::list;
  40 using std::make_pair;
  41 using std::max;
  42 using std::min;
  43 using std::numeric_limits;
  44 using std::set;
  45 using std::string;
  46 using std::vector;
  47
  48 namespace net {
  49
  50 class QuicDecrypter;
  51 class QuicEncrypter;
  52
  53 namespace {
  54
  55 // The largest gap in packets we'll accept without closing the connection.
  56 // This will likely have to be tuned.
  57 const QuicPacketSequenceNumber kMaxPacketGap = 5000;
  58
  59 // Limit the number of FEC groups to two.  If we get enough out of order packets
  60 // that this becomes limiting, we can revisit.
  61 const size_t kMaxFecGroups = 2;
  62
  63 // Maximum number of acks received before sending an ack in response.
  64 const QuicPacketCount kMaxPacketsReceivedBeforeAckSend = 20;
  65
  66 // Maximum number of tracked packets.
  67 const QuicPacketCount kMaxTrackedPackets = 5000;
  68
  69 bool Near(QuicPacketSequenceNumber a, QuicPacketSequenceNumber b) {
  70   QuicPacketSequenceNumber delta = (a > b) ? a - b : b - a;
  71   return delta <= kMaxPacketGap;
  72 }
  73
  74 // An alarm that is scheduled to send an ack if a timeout occurs.
  75 class AckAlarm : public QuicAlarm::Delegate {
  76  public:
  77   explicit AckAlarm(QuicConnection* connection)
  78       : connection_(connection) {
  79   }
  80
  81   QuicTime OnAlarm() override {
  82     connection_->SendAck();
  83     return QuicTime::Zero();
  84   }
  85
  86  private:
  87   QuicConnection* connection_;
  88
  89   DISALLOW_COPY_AND_ASSIGN(AckAlarm);
  90 };
  91
  92 // This alarm will be scheduled any time a data-bearing packet is sent out.
  93 // When the alarm goes off, the connection checks to see if the oldest packets
  94 // have been acked, and retransmit them if they have not.
  95 class RetransmissionAlarm : public QuicAlarm::Delegate {
  96  public:
  97   explicit RetransmissionAlarm(QuicConnection* connection)
  98       : connection_(connection) {
  99   }
 100
 101   QuicTime OnAlarm() override {
 102     connection_->OnRetransmissionTimeout();
 103     return QuicTime::Zero();
 104   }
 105
 106  private:
 107   QuicConnection* connection_;
 108
 109   DISALLOW_COPY_AND_ASSIGN(RetransmissionAlarm);
 110 };
 111
 112 // An alarm that is scheduled when the SentPacketManager requires a delay
 113 // before sending packets and fires when the packet may be sent.
 114 class SendAlarm : public QuicAlarm::Delegate {
 115  public:
 116   explicit SendAlarm(QuicConnection* connection)
 117       : connection_(connection) {
 118   }
 119
 120   QuicTime OnAlarm() override {
 121     connection_->WriteIfNotBlocked();
 122     // Never reschedule the alarm, since CanWrite does that.
 123     return QuicTime::Zero();
 124   }
 125
 126  private:
 127   QuicConnection* connection_;
 128
 129   DISALLOW_COPY_AND_ASSIGN(SendAlarm);
 130 };
 131
 132 class TimeoutAlarm : public QuicAlarm::Delegate {
 133  public:
 134   explicit TimeoutAlarm(QuicConnection* connection)
 135       : connection_(connection) {
 136   }
 137
 138   QuicTime OnAlarm() override {
 139     connection_->CheckForTimeout();
 140     // Never reschedule the alarm, since CheckForTimeout does that.
 141     return QuicTime::Zero();
 142   }
 143
 144  private:
 145   QuicConnection* connection_;
 146
 147   DISALLOW_COPY_AND_ASSIGN(TimeoutAlarm);
 148 };
 149
 150 class PingAlarm : public QuicAlarm::Delegate {
 151  public:
 152   explicit PingAlarm(QuicConnection* connection)
 153       : connection_(connection) {
 154   }
 155
 156   QuicTime OnAlarm() override {
 157     connection_->SendPing();
 158     return QuicTime::Zero();
 159   }
 160
 161  private:
 162   QuicConnection* connection_;
 163
 164   DISALLOW_COPY_AND_ASSIGN(PingAlarm);
 165 };
 166
 167 // This alarm may be scheduled when an FEC protected packet is sent out.
 168 class FecAlarm : public QuicAlarm::Delegate {
 169  public:
 170   explicit FecAlarm(QuicPacketGenerator* packet_generator)
 171       : packet_generator_(packet_generator) {}
 172
 173   QuicTime OnAlarm() override {
 174     packet_generator_->OnFecTimeout();
 175     return QuicTime::Zero();
 176   }
 177
 178  private:
 179   QuicPacketGenerator* packet_generator_;
 180
 181   DISALLOW_COPY_AND_ASSIGN(FecAlarm);
 182 };
 183
 184 }  // namespace
 185
 186 QuicConnection::QueuedPacket::QueuedPacket(SerializedPacket packet,
 187                                            EncryptionLevel level)
 188     : serialized_packet(packet),
 189       encryption_level(level),
 190       transmission_type(NOT_RETRANSMISSION),
 191       original_sequence_number(0) {
 192 }
 193
 194 QuicConnection::QueuedPacket::QueuedPacket(
 195     SerializedPacket packet,
 196     EncryptionLevel level,
 197     TransmissionType transmission_type,
 198     QuicPacketSequenceNumber original_sequence_number)
 199     : serialized_packet(packet),
 200       encryption_level(level),
 201       transmission_type(transmission_type),
 202       original_sequence_number(original_sequence_number) {
 203 }
 204
 205 #define ENDPOINT \
 206   (perspective_ == Perspective::IS_SERVER ? "Server: " : "Client: ")
 207
 208 QuicConnection::QuicConnection(QuicConnectionId connection_id,
 209                                IPEndPoint address,
 210                                QuicConnectionHelperInterface* helper,
 211                                const PacketWriterFactory& writer_factory,
 212                                bool owns_writer,
 213                                Perspective perspective,
 214                                bool is_secure,
 215                                const QuicVersionVector& supported_versions)
 216     : framer_(supported_versions,
 217               helper->GetClock()->ApproximateNow(),
 218               perspective),
 219       helper_(helper),
 220       writer_(writer_factory.Create(this)),
 221       owns_writer_(owns_writer),
 222       encryption_level_(ENCRYPTION_NONE),
 223       has_forward_secure_encrypter_(false),
 224       first_required_forward_secure_packet_(0),
 225       clock_(helper->GetClock()),
 226       random_generator_(helper->GetRandomGenerator()),
 227       connection_id_(connection_id),
 228       peer_address_(address),
 229       migrating_peer_port_(0),
 230       last_packet_decrypted_(false),
 231       last_packet_revived_(false),
 232       last_size_(0),
 233       last_decrypted_packet_level_(ENCRYPTION_NONE),
 234       largest_seen_packet_with_ack_(0),
 235       largest_seen_packet_with_stop_waiting_(0),
 236       max_undecryptable_packets_(0),
 237       pending_version_negotiation_packet_(false),
 238       silent_close_enabled_(false),
 239       received_packet_manager_(&stats_),
 240       ack_queued_(false),
 241       num_packets_received_since_last_ack_sent_(0),
 242       stop_waiting_count_(0),
 243       ack_alarm_(helper->CreateAlarm(new AckAlarm(this))),
 244       retransmission_alarm_(helper->CreateAlarm(new RetransmissionAlarm(this))),
 245       send_alarm_(helper->CreateAlarm(new SendAlarm(this))),
 246       resume_writes_alarm_(helper->CreateAlarm(new SendAlarm(this))),
 247       timeout_alarm_(helper->CreateAlarm(new TimeoutAlarm(this))),
 248       ping_alarm_(helper->CreateAlarm(new PingAlarm(this))),
 249       visitor_(nullptr),
 250       debug_visitor_(nullptr),
 251       packet_generator_(connection_id_, &framer_, random_generator_, this),
 252       fec_alarm_(helper->CreateAlarm(new FecAlarm(&packet_generator_))),
 253       idle_network_timeout_(QuicTime::Delta::Infinite()),
 254       overall_connection_timeout_(QuicTime::Delta::Infinite()),
 255       time_of_last_received_packet_(clock_->ApproximateNow()),
 256       time_of_last_sent_new_packet_(clock_->ApproximateNow()),
 257       sequence_number_of_last_sent_packet_(0),
 258       sent_packet_manager_(
 259           perspective,
 260           clock_,
 261           &stats_,
 262           FLAGS_quic_use_bbr_congestion_control ? kBBR : kCubic,
 263           FLAGS_quic_use_time_loss_detection ? kTime : kNack,
 264           is_secure),
 265       version_negotiation_state_(START_NEGOTIATION),
 266       perspective_(perspective),
 267       connected_(true),
 268       peer_ip_changed_(false),
 269       peer_port_changed_(false),
 270       self_ip_changed_(false),
 271       self_port_changed_(false),
 272       can_truncate_connection_ids_(true),
 273       is_secure_(is_secure) {
 274   DVLOG(1) << ENDPOINT << "Created connection with connection_id: "
 275            << connection_id;
 276   framer_.set_visitor(this);
 277   framer_.set_received_entropy_calculator(&received_packet_manager_);
 278   stats_.connection_creation_time = clock_->ApproximateNow();
 279   sent_packet_manager_.set_network_change_visitor(this);
 280   if (perspective_ == Perspective::IS_SERVER) {
 281     set_max_packet_length(kDefaultServerMaxPacketSize);
 282   }
 283 }
 284
 285 QuicConnection::~QuicConnection() {
 286   if (owns_writer_) {
 287     delete writer_;
 288   }
 289   STLDeleteElements(&undecryptable_packets_);
 290   STLDeleteValues(&group_map_);
 291   for (QueuedPacketList::iterator it = queued_packets_.begin();
 292        it != queued_packets_.end(); ++it) {
 293     delete it->serialized_packet.retransmittable_frames;
 294     delete it->serialized_packet.packet;
 295   }
 296 }
 297
 298 void QuicConnection::SetFromConfig(const QuicConfig& config) {
 299   if (config.negotiated()) {
 300     SetNetworkTimeouts(QuicTime::Delta::Infinite(),
 301                        config.IdleConnectionStateLifetime());
 302     if (config.SilentClose()) {
 303       silent_close_enabled_ = true;
 304     }
 305   } else {
 306     SetNetworkTimeouts(config.max_time_before_crypto_handshake(),
 307                        config.max_idle_time_before_crypto_handshake());
 308   }
 309
 310   sent_packet_manager_.SetFromConfig(config);
 311   if (config.HasReceivedBytesForConnectionId() &&
 312       can_truncate_connection_ids_) {
 313     packet_generator_.SetConnectionIdLength(
 314         config.ReceivedBytesForConnectionId());
 315   }
 316   max_undecryptable_packets_ = config.max_undecryptable_packets();
 317
 318   if (FLAGS_quic_send_fec_packet_only_on_fec_alarm &&
 319       ((perspective_ == Perspective::IS_SERVER &&
 320         config.HasReceivedConnectionOptions() &&
 321         ContainsQuicTag(config.ReceivedConnectionOptions(), kFSPA)) ||
 322        (perspective_ == Perspective::IS_CLIENT &&
 323         config.HasSendConnectionOptions() &&
 324         ContainsQuicTag(config.SendConnectionOptions(), kFSPA)))) {
 325     packet_generator_.set_fec_send_policy(FecSendPolicy::FEC_ALARM_TRIGGER);
 326   }
 327 }
 328
 329 void QuicConnection::OnSendConnectionState(
 330     const CachedNetworkParameters& cached_network_params) {
 331   if (debug_visitor_ != nullptr) {
 332     debug_visitor_->OnSendConnectionState(cached_network_params);
 333   }
 334 }
 335
 336 bool QuicConnection::ResumeConnectionState(
 337     const CachedNetworkParameters& cached_network_params,
 338     bool max_bandwidth_resumption) {
 339   if (debug_visitor_ != nullptr) {
 340     debug_visitor_->OnResumeConnectionState(cached_network_params);
 341   }
 342   return sent_packet_manager_.ResumeConnectionState(cached_network_params,
 343                                                     max_bandwidth_resumption);
 344 }
 345
 346 void QuicConnection::SetNumOpenStreams(size_t num_streams) {
 347   sent_packet_manager_.SetNumOpenStreams(num_streams);
 348 }
 349
 350 bool QuicConnection::SelectMutualVersion(
 351     const QuicVersionVector& available_versions) {
 352   // Try to find the highest mutual version by iterating over supported
 353   // versions, starting with the highest, and breaking out of the loop once we
 354   // find a matching version in the provided available_versions vector.
 355   const QuicVersionVector& supported_versions = framer_.supported_versions();
 356   for (size_t i = 0; i < supported_versions.size(); ++i) {
 357     const QuicVersion& version = supported_versions[i];
 358     if (std::find(available_versions.begin(), available_versions.end(),
 359                   version) != available_versions.end()) {
 360       framer_.set_version(version);
 361       return true;
 362     }
 363   }
 364
 365   return false;
 366 }
 367
 368 void QuicConnection::OnError(QuicFramer* framer) {
 369   // Packets that we can not or have not decrypted are dropped.
 370   // TODO(rch): add stats to measure this.
 371   if (!connected_ || last_packet_decrypted_ == false) {
 372     return;
 373   }
 374   SendConnectionCloseWithDetails(framer->error(), framer->detailed_error());
 375 }
 376
 377 void QuicConnection::MaybeSetFecAlarm(
 378     QuicPacketSequenceNumber sequence_number) {
 379   if (fec_alarm_->IsSet()) {
 380     return;
 381   }
 382   QuicTime::Delta timeout = packet_generator_.GetFecTimeout(sequence_number);
 383   if (!timeout.IsInfinite()) {
 384     fec_alarm_->Set(clock_->ApproximateNow().Add(timeout));
 385   }
 386 }
 387
 388 void QuicConnection::OnPacket() {
 389   DCHECK(last_stream_frames_.empty() &&
 390          last_ack_frames_.empty() &&
 391          last_stop_waiting_frames_.empty() &&
 392          last_rst_frames_.empty() &&
 393          last_goaway_frames_.empty() &&
 394          last_window_update_frames_.empty() &&
 395          last_blocked_frames_.empty() &&
 396          last_ping_frames_.empty() &&
 397          last_close_frames_.empty());
 398   last_packet_decrypted_ = false;
 399   last_packet_revived_ = false;
 400 }
 401
 402 void QuicConnection::OnPublicResetPacket(const QuicPublicResetPacket& packet) {
 403   // Check that any public reset packet with a different connection ID that was
 404   // routed to this QuicConnection has been redirected before control reaches
 405   // here.  (Check for a bug regression.)
 406   DCHECK_EQ(connection_id_, packet.public_header.connection_id);
 407   if (debug_visitor_ != nullptr) {
 408     debug_visitor_->OnPublicResetPacket(packet);
 409   }
 410   CloseConnection(QUIC_PUBLIC_RESET, true);
 411
 412   DVLOG(1) << ENDPOINT << "Connection " << connection_id()
 413            << " closed via QUIC_PUBLIC_RESET from peer.";
 414 }
 415
 416 bool QuicConnection::OnProtocolVersionMismatch(QuicVersion received_version) {
 417   DVLOG(1) << ENDPOINT << "Received packet with mismatched version "
 418            << received_version;
 419   // TODO(satyamshekhar): Implement no server state in this mode.
 420   if (perspective_ == Perspective::IS_CLIENT) {
 421     LOG(DFATAL) << ENDPOINT << "Framer called OnProtocolVersionMismatch. "
 422                 << "Closing connection.";
 423     CloseConnection(QUIC_INTERNAL_ERROR, false);
 424     return false;
 425   }
 426   DCHECK_NE(version(), received_version);
 427
 428   if (debug_visitor_ != nullptr) {
 429     debug_visitor_->OnProtocolVersionMismatch(received_version);
 430   }
 431
 432   switch (version_negotiation_state_) {
 433     case START_NEGOTIATION:
 434       if (!framer_.IsSupportedVersion(received_version)) {
 435         SendVersionNegotiationPacket();
 436         version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
 437         return false;
 438       }
 439       break;
 440
 441     case NEGOTIATION_IN_PROGRESS:
 442       if (!framer_.IsSupportedVersion(received_version)) {
 443         SendVersionNegotiationPacket();
 444         return false;
 445       }
 446       break;
 447
 448     case NEGOTIATED_VERSION:
 449       // Might be old packets that were sent by the client before the version
 450       // was negotiated. Drop these.
 451       return false;
 452
 453     default:
 454       DCHECK(false);
 455   }
 456
 457   version_negotiation_state_ = NEGOTIATED_VERSION;
 458   visitor_->OnSuccessfulVersionNegotiation(received_version);
 459   if (debug_visitor_ != nullptr) {
 460     debug_visitor_->OnSuccessfulVersionNegotiation(received_version);
 461   }
 462   DVLOG(1) << ENDPOINT << "version negotiated " << received_version;
 463
 464   // Store the new version.
 465   framer_.set_version(received_version);
 466
 467   // TODO(satyamshekhar): Store the sequence number of this packet and close the
 468   // connection if we ever received a packet with incorrect version and whose
 469   // sequence number is greater.
 470   return true;
 471 }
 472
 473 // Handles version negotiation for client connection.
 474 void QuicConnection::OnVersionNegotiationPacket(
 475     const QuicVersionNegotiationPacket& packet) {
 476   // Check that any public reset packet with a different connection ID that was
 477   // routed to this QuicConnection has been redirected before control reaches
 478   // here.  (Check for a bug regression.)
 479   DCHECK_EQ(connection_id_, packet.connection_id);
 480   if (perspective_ == Perspective::IS_SERVER) {
 481     LOG(DFATAL) << ENDPOINT << "Framer parsed VersionNegotiationPacket."
 482                 << " Closing connection.";
 483     CloseConnection(QUIC_INTERNAL_ERROR, false);
 484     return;
 485   }
 486   if (debug_visitor_ != nullptr) {
 487     debug_visitor_->OnVersionNegotiationPacket(packet);
 488   }
 489
 490   if (version_negotiation_state_ != START_NEGOTIATION) {
 491     // Possibly a duplicate version negotiation packet.
 492     return;
 493   }
 494
 495   if (std::find(packet.versions.begin(),
 496                 packet.versions.end(), version()) !=
 497       packet.versions.end()) {
 498     DLOG(WARNING) << ENDPOINT << "The server already supports our version. "
 499                   << "It should have accepted our connection.";
 500     // Just drop the connection.
 501     CloseConnection(QUIC_INVALID_VERSION_NEGOTIATION_PACKET, false);
 502     return;
 503   }
 504
 505   if (!SelectMutualVersion(packet.versions)) {
 506     SendConnectionCloseWithDetails(QUIC_INVALID_VERSION,
 507                                    "no common version found");
 508     return;
 509   }
 510
 511   DVLOG(1) << ENDPOINT
 512            << "Negotiated version: " << QuicVersionToString(version());
 513   server_supported_versions_ = packet.versions;
 514   version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
 515   RetransmitUnackedPackets(ALL_UNACKED_RETRANSMISSION);
 516 }
 517
 518 void QuicConnection::OnRevivedPacket() {
 519 }
 520
 521 bool QuicConnection::OnUnauthenticatedPublicHeader(
 522     const QuicPacketPublicHeader& header) {
 523   if (header.connection_id == connection_id_) {
 524     return true;
 525   }
 526
 527   ++stats_.packets_dropped;
 528   DVLOG(1) << ENDPOINT << "Ignoring packet from unexpected ConnectionId: "
 529            << header.connection_id << " instead of " << connection_id_;
 530   if (debug_visitor_ != nullptr) {
 531     debug_visitor_->OnIncorrectConnectionId(header.connection_id);
 532   }
 533   // If this is a server, the dispatcher routes each packet to the
 534   // QuicConnection responsible for the packet's connection ID.  So if control
 535   // arrives here and this is a server, the dispatcher must be malfunctioning.
 536   DCHECK_NE(Perspective::IS_SERVER, perspective_);
 537   return false;
 538 }
 539
 540 bool QuicConnection::OnUnauthenticatedHeader(const QuicPacketHeader& header) {
 541   // Check that any public reset packet with a different connection ID that was
 542   // routed to this QuicConnection has been redirected before control reaches
 543   // here.
 544   DCHECK_EQ(connection_id_, header.public_header.connection_id);
 545   return true;
 546 }
 547
 548 void QuicConnection::OnDecryptedPacket(EncryptionLevel level) {
 549   last_decrypted_packet_level_ = level;
 550   last_packet_decrypted_ = true;
 551   // If this packet was foward-secure encrypted and the forward-secure encrypter
 552   // is not being used, start using it.
 553   if (encryption_level_ != ENCRYPTION_FORWARD_SECURE &&
 554       has_forward_secure_encrypter_ && level == ENCRYPTION_FORWARD_SECURE) {
 555     SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
 556   }
 557 }
 558
 559 bool QuicConnection::OnPacketHeader(const QuicPacketHeader& header) {
 560   if (debug_visitor_ != nullptr) {
 561     debug_visitor_->OnPacketHeader(header);
 562   }
 563
 564   if (!ProcessValidatedPacket()) {
 565     return false;
 566   }
 567
 568   // Will be decremented below if we fall through to return true.
 569   ++stats_.packets_dropped;
 570
 571   if (!Near(header.packet_sequence_number,
 572             last_header_.packet_sequence_number)) {
 573     DVLOG(1) << ENDPOINT << "Packet " << header.packet_sequence_number
 574              << " out of bounds.  Discarding";
 575     SendConnectionCloseWithDetails(QUIC_INVALID_PACKET_HEADER,
 576                                    "Packet sequence number out of bounds");
 577     return false;
 578   }
 579
 580   // If this packet has already been seen, or the sender has told us that it
 581   // will not be retransmitted, then stop processing the packet.
 582   if (!received_packet_manager_.IsAwaitingPacket(
 583           header.packet_sequence_number)) {
 584     DVLOG(1) << ENDPOINT << "Packet " << header.packet_sequence_number
 585              << " no longer being waited for.  Discarding.";
 586     if (debug_visitor_ != nullptr) {
 587       debug_visitor_->OnDuplicatePacket(header.packet_sequence_number);
 588     }
 589     return false;
 590   }
 591
 592   if (version_negotiation_state_ != NEGOTIATED_VERSION) {
 593     if (perspective_ == Perspective::IS_SERVER) {
 594       if (!header.public_header.version_flag) {
 595         DLOG(WARNING) << ENDPOINT << "Packet " << header.packet_sequence_number
 596                       << " without version flag before version negotiated.";
 597         // Packets should have the version flag till version negotiation is
 598         // done.
 599         CloseConnection(QUIC_INVALID_VERSION, false);
 600         return false;
 601       } else {
 602         DCHECK_EQ(1u, header.public_header.versions.size());
 603         DCHECK_EQ(header.public_header.versions[0], version());
 604         version_negotiation_state_ = NEGOTIATED_VERSION;
 605         visitor_->OnSuccessfulVersionNegotiation(version());
 606         if (debug_visitor_ != nullptr) {
 607           debug_visitor_->OnSuccessfulVersionNegotiation(version());
 608         }
 609       }
 610     } else {
 611       DCHECK(!header.public_header.version_flag);
 612       // If the client gets a packet without the version flag from the server
 613       // it should stop sending version since the version negotiation is done.
 614       packet_generator_.StopSendingVersion();
 615       version_negotiation_state_ = NEGOTIATED_VERSION;
 616       visitor_->OnSuccessfulVersionNegotiation(version());
 617       if (debug_visitor_ != nullptr) {
 618         debug_visitor_->OnSuccessfulVersionNegotiation(version());
 619       }
 620     }
 621   }
 622
 623   DCHECK_EQ(NEGOTIATED_VERSION, version_negotiation_state_);
 624
 625   --stats_.packets_dropped;
 626   DVLOG(1) << ENDPOINT << "Received packet header: " << header;
 627   last_header_ = header;
 628   DCHECK(connected_);
 629   return true;
 630 }
 631
 632 void QuicConnection::OnFecProtectedPayload(StringPiece payload) {
 633   DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
 634   DCHECK_NE(0u, last_header_.fec_group);
 635   QuicFecGroup* group = GetFecGroup();
 636   if (group != nullptr) {
 637     group->Update(last_decrypted_packet_level_, last_header_, payload);
 638   }
 639 }
 640
 641 bool QuicConnection::OnStreamFrame(const QuicStreamFrame& frame) {
 642   DCHECK(connected_);
 643   if (debug_visitor_ != nullptr) {
 644     debug_visitor_->OnStreamFrame(frame);
 645   }
 646   if (frame.stream_id != kCryptoStreamId &&
 647       last_decrypted_packet_level_ == ENCRYPTION_NONE) {
 648     DLOG(WARNING) << ENDPOINT
 649                   << "Received an unencrypted data frame: closing connection";
 650     SendConnectionClose(QUIC_UNENCRYPTED_STREAM_DATA);
 651     return false;
 652   }
 653   last_stream_frames_.push_back(frame);
 654   return true;
 655 }
 656
 657 bool QuicConnection::OnAckFrame(const QuicAckFrame& incoming_ack) {
 658   DCHECK(connected_);
 659   if (debug_visitor_ != nullptr) {
 660     debug_visitor_->OnAckFrame(incoming_ack);
 661   }
 662   DVLOG(1) << ENDPOINT << "OnAckFrame: " << incoming_ack;
 663
 664   if (last_header_.packet_sequence_number <= largest_seen_packet_with_ack_) {
 665     DVLOG(1) << ENDPOINT << "Received an old ack frame: ignoring";
 666     return true;
 667   }
 668
 669   if (!ValidateAckFrame(incoming_ack)) {
 670     SendConnectionClose(QUIC_INVALID_ACK_DATA);
 671     return false;
 672   }
 673
 674   last_ack_frames_.push_back(incoming_ack);
 675   return connected_;
 676 }
 677
 678 void QuicConnection::ProcessAckFrame(const QuicAckFrame& incoming_ack) {
 679   largest_seen_packet_with_ack_ = last_header_.packet_sequence_number;
 680   sent_packet_manager_.OnIncomingAck(incoming_ack,
 681                                      time_of_last_received_packet_);
 682   sent_entropy_manager_.ClearEntropyBefore(
 683       sent_packet_manager_.least_packet_awaited_by_peer() - 1);
 684   if (sent_packet_manager_.HasPendingRetransmissions()) {
 685     WriteIfNotBlocked();
 686   }
 687
 688   // Always reset the retransmission alarm when an ack comes in, since we now
 689   // have a better estimate of the current rtt than when it was set.
 690   QuicTime retransmission_time = sent_packet_manager_.GetRetransmissionTime();
 691   retransmission_alarm_->Update(retransmission_time,
 692                                 QuicTime::Delta::FromMilliseconds(1));
 693 }
 694
 695 void QuicConnection::ProcessStopWaitingFrame(
 696     const QuicStopWaitingFrame& stop_waiting) {
 697   largest_seen_packet_with_stop_waiting_ = last_header_.packet_sequence_number;
 698   received_packet_manager_.UpdatePacketInformationSentByPeer(stop_waiting);
 699   // Possibly close any FecGroups which are now irrelevant.
 700   CloseFecGroupsBefore(stop_waiting.least_unacked + 1);
 701 }
 702
 703 bool QuicConnection::OnStopWaitingFrame(const QuicStopWaitingFrame& frame) {
 704   DCHECK(connected_);
 705
 706   if (last_header_.packet_sequence_number <=
 707       largest_seen_packet_with_stop_waiting_) {
 708     DVLOG(1) << ENDPOINT << "Received an old stop waiting frame: ignoring";
 709     return true;
 710   }
 711
 712   if (!ValidateStopWaitingFrame(frame)) {
 713     SendConnectionClose(QUIC_INVALID_STOP_WAITING_DATA);
 714     return false;
 715   }
 716
 717   if (debug_visitor_ != nullptr) {
 718     debug_visitor_->OnStopWaitingFrame(frame);
 719   }
 720
 721   last_stop_waiting_frames_.push_back(frame);
 722   return connected_;
 723 }
 724
 725 bool QuicConnection::OnPingFrame(const QuicPingFrame& frame) {
 726   DCHECK(connected_);
 727   if (debug_visitor_ != nullptr) {
 728     debug_visitor_->OnPingFrame(frame);
 729   }
 730   last_ping_frames_.push_back(frame);
 731   return true;
 732 }
 733
 734 bool QuicConnection::ValidateAckFrame(const QuicAckFrame& incoming_ack) {
 735   if (incoming_ack.largest_observed > packet_generator_.sequence_number()) {
 736     DLOG(ERROR) << ENDPOINT << "Peer's observed unsent packet:"
 737                 << incoming_ack.largest_observed << " vs "
 738                 << packet_generator_.sequence_number();
 739     // We got an error for data we have not sent.  Error out.
 740     return false;
 741   }
 742
 743   if (incoming_ack.largest_observed < sent_packet_manager_.largest_observed()) {
 744     DLOG(ERROR) << ENDPOINT << "Peer's largest_observed packet decreased:"
 745                 << incoming_ack.largest_observed << " vs "
 746                 << sent_packet_manager_.largest_observed();
 747     // A new ack has a diminished largest_observed value.  Error out.
 748     // If this was an old packet, we wouldn't even have checked.
 749     return false;
 750   }
 751
 752   if (!incoming_ack.missing_packets.empty() &&
 753       *incoming_ack.missing_packets.rbegin() > incoming_ack.largest_observed) {
 754     DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
 755                 << *incoming_ack.missing_packets.rbegin()
 756                 << " which is greater than largest observed: "
 757                 << incoming_ack.largest_observed;
 758     return false;
 759   }
 760
 761   if (!incoming_ack.missing_packets.empty() &&
 762       *incoming_ack.missing_packets.begin() <
 763           sent_packet_manager_.least_packet_awaited_by_peer()) {
 764     DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
 765                 << *incoming_ack.missing_packets.begin()
 766                 << " which is smaller than least_packet_awaited_by_peer_: "
 767                 << sent_packet_manager_.least_packet_awaited_by_peer();
 768     return false;
 769   }
 770
 771   if (!sent_entropy_manager_.IsValidEntropy(
 772           incoming_ack.largest_observed,
 773           incoming_ack.missing_packets,
 774           incoming_ack.entropy_hash)) {
 775     DLOG(ERROR) << ENDPOINT << "Peer sent invalid entropy.";
 776     return false;
 777   }
 778
 779   for (QuicPacketSequenceNumber revived_packet : incoming_ack.revived_packets) {
 780     if (!ContainsKey(incoming_ack.missing_packets, revived_packet)) {
 781       DLOG(ERROR) << ENDPOINT
 782                   << "Peer specified revived packet which was not missing.";
 783       return false;
 784     }
 785   }
 786   return true;
 787 }
 788
 789 bool QuicConnection::ValidateStopWaitingFrame(
 790     const QuicStopWaitingFrame& stop_waiting) {
 791   if (stop_waiting.least_unacked <
 792       received_packet_manager_.peer_least_packet_awaiting_ack()) {
 793     DLOG(ERROR) << ENDPOINT << "Peer's sent low least_unacked: "
 794                 << stop_waiting.least_unacked << " vs "
 795                 << received_packet_manager_.peer_least_packet_awaiting_ack();
 796     // We never process old ack frames, so this number should only increase.
 797     return false;
 798   }
 799
 800   if (stop_waiting.least_unacked >
 801       last_header_.packet_sequence_number) {
 802     DLOG(ERROR) << ENDPOINT << "Peer sent least_unacked:"
 803                 << stop_waiting.least_unacked
 804                 << " greater than the enclosing packet sequence number:"
 805                 << last_header_.packet_sequence_number;
 806     return false;
 807   }
 808
 809   return true;
 810 }
 811
 812 void QuicConnection::OnFecData(const QuicFecData& fec) {
 813   DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
 814   DCHECK_NE(0u, last_header_.fec_group);
 815   QuicFecGroup* group = GetFecGroup();
 816   if (group != nullptr) {
 817     group->UpdateFec(last_decrypted_packet_level_,
 818                      last_header_.packet_sequence_number, fec);
 819   }
 820 }
 821
 822 bool QuicConnection::OnRstStreamFrame(const QuicRstStreamFrame& frame) {
 823   DCHECK(connected_);
 824   if (debug_visitor_ != nullptr) {
 825     debug_visitor_->OnRstStreamFrame(frame);
 826   }
 827   DVLOG(1) << ENDPOINT << "Stream reset with error "
 828            << QuicUtils::StreamErrorToString(frame.error_code);
 829   last_rst_frames_.push_back(frame);
 830   return connected_;
 831 }
 832
 833 bool QuicConnection::OnConnectionCloseFrame(
 834     const QuicConnectionCloseFrame& frame) {
 835   DCHECK(connected_);
 836   if (debug_visitor_ != nullptr) {
 837     debug_visitor_->OnConnectionCloseFrame(frame);
 838   }
 839   DVLOG(1) << ENDPOINT << "Connection " << connection_id()
 840            << " closed with error "
 841            << QuicUtils::ErrorToString(frame.error_code)
 842            << " " << frame.error_details;
 843   last_close_frames_.push_back(frame);
 844   return connected_;
 845 }
 846
 847 bool QuicConnection::OnGoAwayFrame(const QuicGoAwayFrame& frame) {
 848   DCHECK(connected_);
 849   if (debug_visitor_ != nullptr) {
 850     debug_visitor_->OnGoAwayFrame(frame);
 851   }
 852   DVLOG(1) << ENDPOINT << "Go away received with error "
 853            << QuicUtils::ErrorToString(frame.error_code)
 854            << " and reason:" << frame.reason_phrase;
 855   last_goaway_frames_.push_back(frame);
 856   return connected_;
 857 }
 858
 859 bool QuicConnection::OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) {
 860   DCHECK(connected_);
 861   if (debug_visitor_ != nullptr) {
 862     debug_visitor_->OnWindowUpdateFrame(frame);
 863   }
 864   DVLOG(1) << ENDPOINT << "WindowUpdate received for stream: "
 865            << frame.stream_id << " with byte offset: " << frame.byte_offset;
 866   last_window_update_frames_.push_back(frame);
 867   return connected_;
 868 }
 869
 870 bool QuicConnection::OnBlockedFrame(const QuicBlockedFrame& frame) {
 871   DCHECK(connected_);
 872   if (debug_visitor_ != nullptr) {
 873     debug_visitor_->OnBlockedFrame(frame);
 874   }
 875   DVLOG(1) << ENDPOINT << "Blocked frame received for stream: "
 876            << frame.stream_id;
 877   last_blocked_frames_.push_back(frame);
 878   return connected_;
 879 }
 880
 881 void QuicConnection::OnPacketComplete() {
 882   // Don't do anything if this packet closed the connection.
 883   if (!connected_) {
 884     ClearLastFrames();
 885     return;
 886   }
 887
 888   DVLOG(1) << ENDPOINT << (last_packet_revived_ ? "Revived" : "Got")
 889            << " packet " << last_header_.packet_sequence_number << " with "  //
 890            << last_stream_frames_.size() << " stream frames, "               //
 891            << last_ack_frames_.size() << " acks, "                           //
 892            << last_stop_waiting_frames_.size() << " stop_waiting, "          //
 893            << last_rst_frames_.size() << " rsts, "                           //
 894            << last_goaway_frames_.size() << " goaways, "                     //
 895            << last_window_update_frames_.size() << " window updates, "       //
 896            << last_blocked_frames_.size() << " blocked, "                    //
 897            << last_ping_frames_.size() << " pings, "                         //
 898            << last_close_frames_.size() << " closes "                        //
 899            << "for " << last_header_.public_header.connection_id;
 900
 901   ++num_packets_received_since_last_ack_sent_;
 902
 903   // Call MaybeQueueAck() before recording the received packet, since we want
 904   // to trigger an ack if the newly received packet was previously missing.
 905   MaybeQueueAck();
 906
 907   // Record received or revived packet to populate ack info correctly before
 908   // processing stream frames, since the processing may result in a response
 909   // packet with a bundled ack.
 910   if (last_packet_revived_) {
 911     received_packet_manager_.RecordPacketRevived(
 912         last_header_.packet_sequence_number);
 913   } else {
 914     received_packet_manager_.RecordPacketReceived(
 915         last_size_, last_header_, time_of_last_received_packet_);
 916   }
 917
 918   if (!last_stream_frames_.empty()) {
 919     visitor_->OnStreamFrames(last_stream_frames_);
 920     if (!connected_ && FLAGS_quic_stop_early_2) {
 921       return;
 922     }
 923   }
 924
 925   for (const QuicStreamFrame& stream_frame : last_stream_frames_) {
 926     stats_.stream_bytes_received += stream_frame.data.size();
 927   }
 928   // Process window updates, blocked, stream resets, acks, then congestion
 929   // feedback.
 930   if (!last_window_update_frames_.empty()) {
 931     visitor_->OnWindowUpdateFrames(last_window_update_frames_);
 932     if (!connected_ && FLAGS_quic_stop_early_2) {
 933       return;
 934     }
 935   }
 936   if (!last_blocked_frames_.empty()) {
 937     visitor_->OnBlockedFrames(last_blocked_frames_);
 938     if (!connected_ && FLAGS_quic_stop_early_2) {
 939       return;
 940     }
 941   }
 942   for (size_t i = 0; i < last_goaway_frames_.size(); ++i) {
 943     visitor_->OnGoAway(last_goaway_frames_[i]);
 944     if (!connected_ && FLAGS_quic_stop_early_2) {
 945       return;
 946     }
 947   }
 948   for (size_t i = 0; i < last_rst_frames_.size(); ++i) {
 949     visitor_->OnRstStream(last_rst_frames_[i]);
 950     if (!connected_ && FLAGS_quic_stop_early_2) {
 951       return;
 952     }
 953   }
 954   for (size_t i = 0; i < last_ack_frames_.size(); ++i) {
 955     ProcessAckFrame(last_ack_frames_[i]);
 956     if (!connected_ && FLAGS_quic_stop_early_2) {
 957       return;
 958     }
 959   }
 960   for (size_t i = 0; i < last_stop_waiting_frames_.size(); ++i) {
 961     ProcessStopWaitingFrame(last_stop_waiting_frames_[i]);
 962     if (!connected_ && FLAGS_quic_stop_early_2) {
 963       return;
 964     }
 965   }
 966   if (!last_close_frames_.empty()) {
 967     CloseConnection(last_close_frames_[0].error_code, true);
 968     DCHECK(!connected_);
 969     if (FLAGS_quic_stop_early_2) {
 970       return;
 971     }
 972   }
 973
 974   // If there are new missing packets to report, send an ack immediately.
 975   if ((!FLAGS_quic_dont_ack_acks || ShouldLastPacketInstigateAck()) &&
 976       received_packet_manager_.HasNewMissingPackets()) {
 977     ack_queued_ = true;
 978     ack_alarm_->Cancel();
 979   }
 980
 981   UpdateStopWaitingCount();
 982   ClearLastFrames();
 983   MaybeCloseIfTooManyOutstandingPackets();
 984 }
 985
 986 void QuicConnection::MaybeQueueAck() {
 987   // If the last packet is an ack, don't ack it.
 988   if (!ShouldLastPacketInstigateAck()) {
 989     return;
 990   }
 991   // If the incoming packet was missing, send an ack immediately.
 992   ack_queued_ = received_packet_manager_.IsMissing(
 993       last_header_.packet_sequence_number);
 994
 995   if (!ack_queued_) {
 996     if (ack_alarm_->IsSet()) {
 997       ack_queued_ = true;
 998     } else {
 999       ack_alarm_->Set(
1000           clock_->ApproximateNow().Add(sent_packet_manager_.DelayedAckTime()));
1001       DVLOG(1) << "Ack timer set; next packet or timer will trigger ACK.";
1002     }
1003   }
1004
1005   if (ack_queued_) {
1006     ack_alarm_->Cancel();
1007   }
1008 }
1009
1010 void QuicConnection::ClearLastFrames() {
1011   last_stream_frames_.clear();
1012   last_ack_frames_.clear();
1013   last_stop_waiting_frames_.clear();
1014   last_rst_frames_.clear();
1015   last_goaway_frames_.clear();
1016   last_window_update_frames_.clear();
1017   last_blocked_frames_.clear();
1018   last_ping_frames_.clear();
1019   last_close_frames_.clear();
1020 }
1021
1022 void QuicConnection::MaybeCloseIfTooManyOutstandingPackets() {
1023   // This occurs if we don't discard old packets we've sent fast enough.
1024   // It's possible largest observed is less than least unacked.
1025   if (sent_packet_manager_.largest_observed() >
1026           (sent_packet_manager_.GetLeastUnacked() + kMaxTrackedPackets)) {
1027     SendConnectionCloseWithDetails(
1028         QUIC_TOO_MANY_OUTSTANDING_SENT_PACKETS,
1029         StringPrintf("More than %" PRIu64 " outstanding.", kMaxTrackedPackets));
1030   }
1031   // This occurs if there are received packet gaps and the peer does not raise
1032   // the least unacked fast enough.
1033   if (received_packet_manager_.NumTrackedPackets() > kMaxTrackedPackets) {
1034     SendConnectionCloseWithDetails(
1035         QUIC_TOO_MANY_OUTSTANDING_RECEIVED_PACKETS,
1036         StringPrintf("More than %" PRIu64 " outstanding.", kMaxTrackedPackets));
1037   }
1038 }
1039
1040 void QuicConnection::PopulateAckFrame(QuicAckFrame* ack) {
1041   received_packet_manager_.UpdateReceivedPacketInfo(ack,
1042                                                     clock_->ApproximateNow());
1043 }
1044
1045 void QuicConnection::PopulateStopWaitingFrame(
1046     QuicStopWaitingFrame* stop_waiting) {
1047   stop_waiting->least_unacked = GetLeastUnacked();
1048   stop_waiting->entropy_hash = sent_entropy_manager_.GetCumulativeEntropy(
1049       stop_waiting->least_unacked - 1);
1050 }
1051
1052 bool QuicConnection::ShouldLastPacketInstigateAck() const {
1053   if (!last_stream_frames_.empty() ||
1054       !last_goaway_frames_.empty() ||
1055       !last_rst_frames_.empty() ||
1056       !last_window_update_frames_.empty() ||
1057       !last_blocked_frames_.empty() ||
1058       !last_ping_frames_.empty()) {
1059     return true;
1060   }
1061
1062   if (!last_ack_frames_.empty() && last_ack_frames_.back().is_truncated) {
1063     return true;
1064   }
1065   // Always send an ack every 20 packets in order to allow the peer to discard
1066   // information from the SentPacketManager and provide an RTT measurement.
1067   if (num_packets_received_since_last_ack_sent_ >=
1068           kMaxPacketsReceivedBeforeAckSend) {
1069     return true;
1070   }
1071   return false;
1072 }
1073
1074 void QuicConnection::UpdateStopWaitingCount() {
1075   if (last_ack_frames_.empty()) {
1076     return;
1077   }
1078
1079   // If the peer is still waiting for a packet that we are no longer planning to
1080   // send, send an ack to raise the high water mark.
1081   if (!last_ack_frames_.back().missing_packets.empty() &&
1082       GetLeastUnacked() > *last_ack_frames_.back().missing_packets.begin()) {
1083     ++stop_waiting_count_;
1084   } else {
1085     stop_waiting_count_ = 0;
1086   }
1087 }
1088
1089 QuicPacketSequenceNumber QuicConnection::GetLeastUnacked() const {
1090   return sent_packet_manager_.GetLeastUnacked();
1091 }
1092
1093 void QuicConnection::MaybeSendInResponseToPacket() {
1094   if (!connected_) {
1095     return;
1096   }
1097   ScopedPacketBundler bundler(this, ack_queued_ ? SEND_ACK : NO_ACK);
1098
1099   // Now that we have received an ack, we might be able to send packets which
1100   // are queued locally, or drain streams which are blocked.
1101   if (CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1102     OnCanWrite();
1103   }
1104 }
1105
1106 void QuicConnection::SendVersionNegotiationPacket() {
1107   // TODO(alyssar): implement zero server state negotiation.
1108   pending_version_negotiation_packet_ = true;
1109   if (writer_->IsWriteBlocked()) {
1110     visitor_->OnWriteBlocked();
1111     return;
1112   }
1113   DVLOG(1) << ENDPOINT << "Sending version negotiation packet: {"
1114            << QuicVersionVectorToString(framer_.supported_versions()) << "}";
1115   scoped_ptr<QuicEncryptedPacket> version_packet(
1116       packet_generator_.SerializeVersionNegotiationPacket(
1117           framer_.supported_versions()));
1118   WriteResult result = writer_->WritePacket(
1119       version_packet->data(), version_packet->length(),
1120       self_address().address(), peer_address());
1121
1122   if (result.status == WRITE_STATUS_ERROR) {
1123     // We can't send an error as the socket is presumably borked.
1124     CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
1125     return;
1126   }
1127   if (result.status == WRITE_STATUS_BLOCKED) {
1128     visitor_->OnWriteBlocked();
1129     if (writer_->IsWriteBlockedDataBuffered()) {
1130       pending_version_negotiation_packet_ = false;
1131     }
1132     return;
1133   }
1134
1135   pending_version_negotiation_packet_ = false;
1136 }
1137
1138 QuicConsumedData QuicConnection::SendStreamData(
1139     QuicStreamId id,
1140     const QuicIOVector& iov,
1141     QuicStreamOffset offset,
1142     bool fin,
1143     FecProtection fec_protection,
1144     QuicAckNotifier::DelegateInterface* delegate) {
1145   if (!fin && iov.total_length == 0) {
1146     LOG(DFATAL) << "Attempt to send empty stream frame";
1147     return QuicConsumedData(0, false);
1148   }
1149
1150   // Opportunistically bundle an ack with every outgoing packet.
1151   // Particularly, we want to bundle with handshake packets since we don't know
1152   // which decrypter will be used on an ack packet following a handshake
1153   // packet (a handshake packet from client to server could result in a REJ or a
1154   // SHLO from the server, leading to two different decrypters at the server.)
1155   //
1156   // TODO(jri): Note that ConsumeData may cause a response packet to be sent.
1157   // We may end up sending stale ack information if there are undecryptable
1158   // packets hanging around and/or there are revivable packets which may get
1159   // handled after this packet is sent. Change ScopedPacketBundler to do the
1160   // right thing: check ack_queued_, and then check undecryptable packets and
1161   // also if there is possibility of revival. Only bundle an ack if there's no
1162   // processing left that may cause received_info_ to change.
1163   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1164   return packet_generator_.ConsumeData(id, iov, offset, fin, fec_protection,
1165                                        delegate);
1166 }
1167
1168 void QuicConnection::SendRstStream(QuicStreamId id,
1169                                    QuicRstStreamErrorCode error,
1170                                    QuicStreamOffset bytes_written) {
1171   // Opportunistically bundle an ack with this outgoing packet.
1172   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1173   packet_generator_.AddControlFrame(QuicFrame(new QuicRstStreamFrame(
1174       id, AdjustErrorForVersion(error, version()), bytes_written)));
1175
1176   sent_packet_manager_.CancelRetransmissionsForStream(id);
1177   // Remove all queued packets which only contain data for the reset stream.
1178   QueuedPacketList::iterator packet_iterator = queued_packets_.begin();
1179   while (packet_iterator != queued_packets_.end()) {
1180     RetransmittableFrames* retransmittable_frames =
1181         packet_iterator->serialized_packet.retransmittable_frames;
1182     if (!retransmittable_frames) {
1183       ++packet_iterator;
1184       continue;
1185     }
1186     retransmittable_frames->RemoveFramesForStream(id);
1187     if (!retransmittable_frames->frames().empty()) {
1188       ++packet_iterator;
1189       continue;
1190     }
1191     delete packet_iterator->serialized_packet.retransmittable_frames;
1192     delete packet_iterator->serialized_packet.packet;
1193     packet_iterator->serialized_packet.retransmittable_frames = nullptr;
1194     packet_iterator->serialized_packet.packet = nullptr;
1195     packet_iterator = queued_packets_.erase(packet_iterator);
1196   }
1197 }
1198
1199 void QuicConnection::SendWindowUpdate(QuicStreamId id,
1200                                       QuicStreamOffset byte_offset) {
1201   // Opportunistically bundle an ack with this outgoing packet.
1202   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1203   packet_generator_.AddControlFrame(
1204       QuicFrame(new QuicWindowUpdateFrame(id, byte_offset)));
1205 }
1206
1207 void QuicConnection::SendBlocked(QuicStreamId id) {
1208   // Opportunistically bundle an ack with this outgoing packet.
1209   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1210   packet_generator_.AddControlFrame(QuicFrame(new QuicBlockedFrame(id)));
1211 }
1212
1213 const QuicConnectionStats& QuicConnection::GetStats() {
1214   const RttStats* rtt_stats = sent_packet_manager_.GetRttStats();
1215
1216   // Update rtt and estimated bandwidth.
1217   QuicTime::Delta min_rtt = rtt_stats->min_rtt();
1218   if (min_rtt.IsZero()) {
1219     // If min RTT has not been set, use initial RTT instead.
1220     min_rtt = QuicTime::Delta::FromMicroseconds(rtt_stats->initial_rtt_us());
1221   }
1222   stats_.min_rtt_us = min_rtt.ToMicroseconds();
1223
1224   QuicTime::Delta srtt = rtt_stats->smoothed_rtt();
1225   if (srtt.IsZero()) {
1226     // If SRTT has not been set, use initial RTT instead.
1227     srtt = QuicTime::Delta::FromMicroseconds(rtt_stats->initial_rtt_us());
1228   }
1229   stats_.srtt_us = srtt.ToMicroseconds();
1230
1231   stats_.estimated_bandwidth = sent_packet_manager_.BandwidthEstimate();
1232   stats_.max_packet_size = packet_generator_.GetMaxPacketLength();
1233   return stats_;
1234 }
1235
1236 void QuicConnection::ProcessUdpPacket(const IPEndPoint& self_address,
1237                                       const IPEndPoint& peer_address,
1238                                       const QuicEncryptedPacket& packet) {
1239   if (!connected_) {
1240     return;
1241   }
1242   // TODO(rtenneti): Remove ScopedTracker below once crbug.com/462789 is fixed.
1243   tracked_objects::ScopedTracker tracking_profile(
1244       FROM_HERE_WITH_EXPLICIT_FUNCTION(
1245           "462789 QuicConnection::ProcessUdpPacket"));
1246   if (debug_visitor_ != nullptr) {
1247     debug_visitor_->OnPacketReceived(self_address, peer_address, packet);
1248   }
1249   last_size_ = packet.length();
1250
1251   CheckForAddressMigration(self_address, peer_address);
1252
1253   stats_.bytes_received += packet.length();
1254   ++stats_.packets_received;
1255
1256   if (!framer_.ProcessPacket(packet)) {
1257     // If we are unable to decrypt this packet, it might be
1258     // because the CHLO or SHLO packet was lost.
1259     if (framer_.error() == QUIC_DECRYPTION_FAILURE) {
1260       if (encryption_level_ != ENCRYPTION_FORWARD_SECURE &&
1261           undecryptable_packets_.size() < max_undecryptable_packets_) {
1262         QueueUndecryptablePacket(packet);
1263       } else if (debug_visitor_ != nullptr) {
1264         debug_visitor_->OnUndecryptablePacket();
1265       }
1266     }
1267     DVLOG(1) << ENDPOINT << "Unable to process packet.  Last packet processed: "
1268              << last_header_.packet_sequence_number;
1269     return;
1270   }
1271
1272   ++stats_.packets_processed;
1273   MaybeProcessUndecryptablePackets();
1274   MaybeProcessRevivedPacket();
1275   MaybeSendInResponseToPacket();
1276   SetPingAlarm();
1277 }
1278
1279 void QuicConnection::CheckForAddressMigration(
1280     const IPEndPoint& self_address, const IPEndPoint& peer_address) {
1281   peer_ip_changed_ = false;
1282   peer_port_changed_ = false;
1283   self_ip_changed_ = false;
1284   self_port_changed_ = false;
1285
1286   if (peer_address_.address().empty()) {
1287     peer_address_ = peer_address;
1288   }
1289   if (self_address_.address().empty()) {
1290     self_address_ = self_address;
1291   }
1292
1293   if (!peer_address.address().empty() && !peer_address_.address().empty()) {
1294     peer_ip_changed_ = (peer_address.address() != peer_address_.address());
1295     peer_port_changed_ = (peer_address.port() != peer_address_.port());
1296
1297     // Store in case we want to migrate connection in ProcessValidatedPacket.
1298     migrating_peer_port_ = peer_address.port();
1299   }
1300
1301   if (!self_address.address().empty() && !self_address_.address().empty()) {
1302     self_ip_changed_ = (self_address.address() != self_address_.address());
1303     self_port_changed_ = (self_address.port() != self_address_.port());
1304   }
1305 }
1306
1307 void QuicConnection::OnCanWrite() {
1308   DCHECK(!writer_->IsWriteBlocked());
1309
1310   WriteQueuedPackets();
1311   WritePendingRetransmissions();
1312
1313   // Sending queued packets may have caused the socket to become write blocked,
1314   // or the congestion manager to prohibit sending.  If we've sent everything
1315   // we had queued and we're still not blocked, let the visitor know it can
1316   // write more.
1317   if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1318     return;
1319   }
1320
1321   { // Limit the scope of the bundler. ACK inclusion happens elsewhere.
1322     ScopedPacketBundler bundler(this, NO_ACK);
1323     visitor_->OnCanWrite();
1324   }
1325
1326   // After the visitor writes, it may have caused the socket to become write
1327   // blocked or the congestion manager to prohibit sending, so check again.
1328   if (visitor_->WillingAndAbleToWrite() &&
1329       !resume_writes_alarm_->IsSet() &&
1330       CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1331     // We're not write blocked, but some stream didn't write out all of its
1332     // bytes. Register for 'immediate' resumption so we'll keep writing after
1333     // other connections and events have had a chance to use the thread.
1334     resume_writes_alarm_->Set(clock_->ApproximateNow());
1335   }
1336 }
1337
1338 void QuicConnection::WriteIfNotBlocked() {
1339   if (!writer_->IsWriteBlocked()) {
1340     OnCanWrite();
1341   }
1342 }
1343
1344 bool QuicConnection::ProcessValidatedPacket() {
1345   if (peer_ip_changed_ || self_ip_changed_ || self_port_changed_) {
1346     SendConnectionCloseWithDetails(
1347         QUIC_ERROR_MIGRATING_ADDRESS,
1348         "Neither IP address migration, nor self port migration are supported.");
1349     return false;
1350   }
1351
1352   // Peer port migration is supported, do it now if port has changed.
1353   if (peer_port_changed_) {
1354     DVLOG(1) << ENDPOINT << "Peer's port changed from "
1355              << peer_address_.port() << " to " << migrating_peer_port_
1356              << ", migrating connection.";
1357     peer_address_ = IPEndPoint(peer_address_.address(), migrating_peer_port_);
1358   }
1359
1360   time_of_last_received_packet_ = clock_->Now();
1361   DVLOG(1) << ENDPOINT << "time of last received packet: "
1362            << time_of_last_received_packet_.ToDebuggingValue();
1363
1364   if (perspective_ == Perspective::IS_SERVER &&
1365       encryption_level_ == ENCRYPTION_NONE &&
1366       last_size_ > packet_generator_.GetMaxPacketLength()) {
1367     set_max_packet_length(last_size_);
1368   }
1369   return true;
1370 }
1371
1372 void QuicConnection::WriteQueuedPackets() {
1373   DCHECK(!writer_->IsWriteBlocked());
1374
1375   if (pending_version_negotiation_packet_) {
1376     SendVersionNegotiationPacket();
1377   }
1378
1379   QueuedPacketList::iterator packet_iterator = queued_packets_.begin();
1380   while (packet_iterator != queued_packets_.end() &&
1381          WritePacket(&(*packet_iterator))) {
1382     packet_iterator = queued_packets_.erase(packet_iterator);
1383   }
1384 }
1385
1386 void QuicConnection::WritePendingRetransmissions() {
1387   // Keep writing as long as there's a pending retransmission which can be
1388   // written.
1389   while (sent_packet_manager_.HasPendingRetransmissions()) {
1390     const QuicSentPacketManager::PendingRetransmission pending =
1391         sent_packet_manager_.NextPendingRetransmission();
1392     if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1393       break;
1394     }
1395
1396     // Re-packetize the frames with a new sequence number for retransmission.
1397     // Retransmitted data packets do not use FEC, even when it's enabled.
1398     // Retransmitted packets use the same sequence number length as the
1399     // original.
1400     // Flush the packet generator before making a new packet.
1401     // TODO(ianswett): Implement ReserializeAllFrames as a separate path that
1402     // does not require the creator to be flushed.
1403     packet_generator_.FlushAllQueuedFrames();
1404     char buffer[kMaxPacketSize];
1405     SerializedPacket serialized_packet = packet_generator_.ReserializeAllFrames(
1406         pending.retransmittable_frames, pending.sequence_number_length, buffer,
1407         kMaxPacketSize);
1408     if (serialized_packet.packet == nullptr) {
1409       // We failed to serialize the packet, so close the connection.
1410       // CloseConnection does not send close packet, so no infinite loop here.
1411       CloseConnection(QUIC_ENCRYPTION_FAILURE, false);
1412       return;
1413     }
1414
1415     DVLOG(1) << ENDPOINT << "Retransmitting " << pending.sequence_number
1416              << " as " << serialized_packet.sequence_number;
1417     SendOrQueuePacket(
1418         QueuedPacket(serialized_packet,
1419                      pending.retransmittable_frames.encryption_level(),
1420                      pending.transmission_type,
1421                      pending.sequence_number));
1422   }
1423 }
1424
1425 void QuicConnection::RetransmitUnackedPackets(
1426     TransmissionType retransmission_type) {
1427   sent_packet_manager_.RetransmitUnackedPackets(retransmission_type);
1428
1429   WriteIfNotBlocked();
1430 }
1431
1432 void QuicConnection::NeuterUnencryptedPackets() {
1433   sent_packet_manager_.NeuterUnencryptedPackets();
1434   // This may have changed the retransmission timer, so re-arm it.
1435   QuicTime retransmission_time = sent_packet_manager_.GetRetransmissionTime();
1436   retransmission_alarm_->Update(retransmission_time,
1437                                 QuicTime::Delta::FromMilliseconds(1));
1438 }
1439
1440 bool QuicConnection::ShouldGeneratePacket(
1441     HasRetransmittableData retransmittable,
1442     IsHandshake handshake) {
1443   // We should serialize handshake packets immediately to ensure that they
1444   // end up sent at the right encryption level.
1445   if (handshake == IS_HANDSHAKE) {
1446     return true;
1447   }
1448
1449   return CanWrite(retransmittable);
1450 }
1451
1452 bool QuicConnection::CanWrite(HasRetransmittableData retransmittable) {
1453   if (!connected_) {
1454     return false;
1455   }
1456
1457   if (writer_->IsWriteBlocked()) {
1458     visitor_->OnWriteBlocked();
1459     return false;
1460   }
1461
1462   QuicTime now = clock_->Now();
1463   QuicTime::Delta delay = sent_packet_manager_.TimeUntilSend(
1464       now, retransmittable);
1465   if (delay.IsInfinite()) {
1466     send_alarm_->Cancel();
1467     return false;
1468   }
1469
1470   // If the scheduler requires a delay, then we can not send this packet now.
1471   if (!delay.IsZero()) {
1472     send_alarm_->Update(now.Add(delay), QuicTime::Delta::FromMilliseconds(1));
1473     DVLOG(1) << ENDPOINT << "Delaying sending " << delay.ToMilliseconds()
1474              << "ms";
1475     return false;
1476   }
1477   send_alarm_->Cancel();
1478   return true;
1479 }
1480
1481 bool QuicConnection::WritePacket(QueuedPacket* packet) {
1482   if (!WritePacketInner(packet)) {
1483     return false;
1484   }
1485   delete packet->serialized_packet.retransmittable_frames;
1486   delete packet->serialized_packet.packet;
1487   packet->serialized_packet.retransmittable_frames = nullptr;
1488   packet->serialized_packet.packet = nullptr;
1489   return true;
1490 }
1491
1492 bool QuicConnection::WritePacketInner(QueuedPacket* packet) {
1493   if (ShouldDiscardPacket(*packet)) {
1494     ++stats_.packets_discarded;
1495     return true;
1496   }
1497   // Connection close packets are encrypted and saved, so don't exit early.
1498   const bool is_connection_close = IsConnectionClose(*packet);
1499   if (writer_->IsWriteBlocked() && !is_connection_close) {
1500     return false;
1501   }
1502
1503   QuicPacketSequenceNumber sequence_number =
1504       packet->serialized_packet.sequence_number;
1505   DCHECK_LE(sequence_number_of_last_sent_packet_, sequence_number);
1506   sequence_number_of_last_sent_packet_ = sequence_number;
1507
1508   QuicEncryptedPacket* encrypted = packet->serialized_packet.packet;
1509   // Connection close packets are eventually owned by TimeWaitListManager.
1510   // Others are deleted at the end of this call.
1511   if (is_connection_close) {
1512     DCHECK(connection_close_packet_.get() == nullptr);
1513     // Clone the packet so it's owned in the future.
1514     connection_close_packet_.reset(encrypted->Clone());
1515     // This assures we won't try to write *forced* packets when blocked.
1516     // Return true to stop processing.
1517     if (writer_->IsWriteBlocked()) {
1518       visitor_->OnWriteBlocked();
1519       return true;
1520     }
1521   }
1522
1523   if (!FLAGS_quic_allow_oversized_packets_for_test) {
1524     DCHECK_LE(encrypted->length(), kMaxPacketSize);
1525   }
1526   DCHECK_LE(encrypted->length(), packet_generator_.GetMaxPacketLength());
1527   DVLOG(1) << ENDPOINT << "Sending packet " << sequence_number << " : "
1528            << (packet->serialized_packet.is_fec_packet
1529                    ? "FEC "
1530                    : (IsRetransmittable(*packet) == HAS_RETRANSMITTABLE_DATA
1531                           ? "data bearing "
1532                           : " ack only ")) << ", encryption level: "
1533            << QuicUtils::EncryptionLevelToString(packet->encryption_level)
1534            << ", encrypted length:" << encrypted->length();
1535   DVLOG(2) << ENDPOINT << "packet(" << sequence_number << "): " << std::endl
1536            << QuicUtils::StringToHexASCIIDump(encrypted->AsStringPiece());
1537
1538   // Measure the RTT from before the write begins to avoid underestimating the
1539   // min_rtt_, especially in cases where the thread blocks or gets swapped out
1540   // during the WritePacket below.
1541   QuicTime packet_send_time = clock_->Now();
1542   WriteResult result = writer_->WritePacket(encrypted->data(),
1543                                             encrypted->length(),
1544                                             self_address().address(),
1545                                             peer_address());
1546   if (result.error_code == ERR_IO_PENDING) {
1547     DCHECK_EQ(WRITE_STATUS_BLOCKED, result.status);
1548   }
1549
1550   if (result.status == WRITE_STATUS_BLOCKED) {
1551     visitor_->OnWriteBlocked();
1552     // If the socket buffers the the data, then the packet should not
1553     // be queued and sent again, which would result in an unnecessary
1554     // duplicate packet being sent.  The helper must call OnCanWrite
1555     // when the write completes, and OnWriteError if an error occurs.
1556     if (!writer_->IsWriteBlockedDataBuffered()) {
1557       return false;
1558     }
1559   }
1560   if (result.status != WRITE_STATUS_ERROR && debug_visitor_ != nullptr) {
1561     // Pass the write result to the visitor.
1562     debug_visitor_->OnPacketSent(packet->serialized_packet,
1563                                  packet->original_sequence_number,
1564                                  packet->encryption_level,
1565                                  packet->transmission_type,
1566                                  *encrypted,
1567                                  packet_send_time);
1568   }
1569   if (packet->transmission_type == NOT_RETRANSMISSION) {
1570     time_of_last_sent_new_packet_ = packet_send_time;
1571   }
1572   SetPingAlarm();
1573   MaybeSetFecAlarm(sequence_number);
1574   DVLOG(1) << ENDPOINT << "time we began writing last sent packet: "
1575            << packet_send_time.ToDebuggingValue();
1576
1577   // TODO(ianswett): Change the sequence number length and other packet creator
1578   // options by a more explicit API than setting a struct value directly,
1579   // perhaps via the NetworkChangeVisitor.
1580   packet_generator_.UpdateSequenceNumberLength(
1581       sent_packet_manager_.least_packet_awaited_by_peer(),
1582       sent_packet_manager_.EstimateMaxPacketsInFlight(max_packet_length()));
1583
1584   bool reset_retransmission_alarm = sent_packet_manager_.OnPacketSent(
1585       &packet->serialized_packet,
1586       packet->original_sequence_number,
1587       packet_send_time,
1588       encrypted->length(),
1589       packet->transmission_type,
1590       IsRetransmittable(*packet));
1591
1592   if (reset_retransmission_alarm || !retransmission_alarm_->IsSet()) {
1593     retransmission_alarm_->Update(sent_packet_manager_.GetRetransmissionTime(),
1594                                   QuicTime::Delta::FromMilliseconds(1));
1595   }
1596
1597   stats_.bytes_sent += result.bytes_written;
1598   ++stats_.packets_sent;
1599   if (packet->transmission_type != NOT_RETRANSMISSION) {
1600     stats_.bytes_retransmitted += result.bytes_written;
1601     ++stats_.packets_retransmitted;
1602   }
1603
1604   if (result.status == WRITE_STATUS_ERROR) {
1605     OnWriteError(result.error_code);
1606     DLOG(ERROR) << ENDPOINT << "failed writing " << encrypted->length()
1607                 << "bytes "
1608                 << " from host " << self_address().ToStringWithoutPort()
1609                 << " to address " << peer_address().ToString();
1610     return false;
1611   }
1612
1613   return true;
1614 }
1615
1616 bool QuicConnection::ShouldDiscardPacket(const QueuedPacket& packet) {
1617   if (!connected_) {
1618     DVLOG(1) << ENDPOINT
1619              << "Not sending packet as connection is disconnected.";
1620     return true;
1621   }
1622
1623   QuicPacketSequenceNumber sequence_number =
1624       packet.serialized_packet.sequence_number;
1625   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE &&
1626       packet.encryption_level == ENCRYPTION_NONE) {
1627     // Drop packets that are NULL encrypted since the peer won't accept them
1628     // anymore.
1629     DVLOG(1) << ENDPOINT << "Dropping NULL encrypted packet: "
1630              << sequence_number << " since the connection is forward secure.";
1631     return true;
1632   }
1633
1634   // If a retransmission has been acked before sending, don't send it.
1635   // This occurs if a packet gets serialized, queued, then discarded.
1636   if (packet.transmission_type != NOT_RETRANSMISSION &&
1637       (!sent_packet_manager_.IsUnacked(packet.original_sequence_number) ||
1638        !sent_packet_manager_.HasRetransmittableFrames(
1639            packet.original_sequence_number))) {
1640     DVLOG(1) << ENDPOINT << "Dropping unacked packet: " << sequence_number
1641              << " A previous transmission was acked while write blocked.";
1642     return true;
1643   }
1644
1645   return false;
1646 }
1647
1648 void QuicConnection::OnWriteError(int error_code) {
1649   DVLOG(1) << ENDPOINT << "Write failed with error: " << error_code
1650            << " (" << ErrorToString(error_code) << ")";
1651   // We can't send an error as the socket is presumably borked.
1652   CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
1653 }
1654
1655 void QuicConnection::OnSerializedPacket(
1656     const SerializedPacket& serialized_packet) {
1657   if (serialized_packet.packet == nullptr) {
1658     // We failed to serialize the packet, so close the connection.
1659     // CloseConnection does not send close packet, so no infinite loop here.
1660     CloseConnection(QUIC_ENCRYPTION_FAILURE, false);
1661     return;
1662   }
1663   if (serialized_packet.retransmittable_frames) {
1664     sent_packet_manager_.OnSerializedPacket(serialized_packet);
1665   }
1666   if (serialized_packet.is_fec_packet && fec_alarm_->IsSet()) {
1667     // If an FEC packet is serialized with the FEC alarm set, cancel the alarm.
1668     fec_alarm_->Cancel();
1669   }
1670   SendOrQueuePacket(QueuedPacket(serialized_packet, encryption_level_));
1671 }
1672
1673 void QuicConnection::OnResetFecGroup() {
1674   if (!fec_alarm_->IsSet()) {
1675     return;
1676   }
1677   // If an FEC Group is closed with the FEC alarm set, cancel the alarm.
1678   fec_alarm_->Cancel();
1679 }
1680
1681 void QuicConnection::OnCongestionWindowChange() {
1682   packet_generator_.OnCongestionWindowChange(
1683       sent_packet_manager_.EstimateMaxPacketsInFlight(max_packet_length()));
1684   visitor_->OnCongestionWindowChange(clock_->ApproximateNow());
1685 }
1686
1687 void QuicConnection::OnRttChange() {
1688   // Uses the connection's smoothed RTT. If zero, uses initial_rtt.
1689   QuicTime::Delta rtt = sent_packet_manager_.GetRttStats()->smoothed_rtt();
1690   if (rtt.IsZero()) {
1691     rtt = QuicTime::Delta::FromMicroseconds(
1692         sent_packet_manager_.GetRttStats()->initial_rtt_us());
1693   }
1694   packet_generator_.OnRttChange(rtt);
1695 }
1696
1697 void QuicConnection::OnHandshakeComplete() {
1698   sent_packet_manager_.SetHandshakeConfirmed();
1699   // The client should immediately ack the SHLO to confirm the handshake is
1700   // complete with the server.
1701   if (perspective_ == Perspective::IS_CLIENT && !ack_queued_) {
1702     ack_alarm_->Cancel();
1703     ack_alarm_->Set(clock_->ApproximateNow());
1704   }
1705 }
1706
1707 void QuicConnection::SendOrQueuePacket(QueuedPacket packet) {
1708   // The caller of this function is responsible for checking CanWrite().
1709   if (packet.serialized_packet.packet == nullptr) {
1710     LOG(DFATAL)
1711         << "packet.serialized_packet.packet == nullptr in to SendOrQueuePacket";
1712     return;
1713   }
1714
1715   sent_entropy_manager_.RecordPacketEntropyHash(
1716       packet.serialized_packet.sequence_number,
1717       packet.serialized_packet.entropy_hash);
1718   if (!WritePacket(&packet)) {
1719     // Take ownership of the underlying encrypted packet.
1720     if (!packet.serialized_packet.packet->owns_buffer()) {
1721       scoped_ptr<QuicEncryptedPacket> encrypted_deleter(
1722           packet.serialized_packet.packet);
1723       packet.serialized_packet.packet =
1724           packet.serialized_packet.packet->Clone();
1725     }
1726     queued_packets_.push_back(packet);
1727   }
1728
1729   // If a forward-secure encrypter is available but is not being used and the
1730   // next sequence number is the first packet which requires
1731   // forward security, start using the forward-secure encrypter.
1732   if (encryption_level_ != ENCRYPTION_FORWARD_SECURE &&
1733       has_forward_secure_encrypter_ &&
1734       packet.serialized_packet.sequence_number >=
1735           first_required_forward_secure_packet_ - 1) {
1736     SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
1737   }
1738 }
1739
1740 void QuicConnection::SendPing() {
1741   if (retransmission_alarm_->IsSet()) {
1742     return;
1743   }
1744   packet_generator_.AddControlFrame(QuicFrame(new QuicPingFrame));
1745 }
1746
1747 void QuicConnection::SendAck() {
1748   ack_alarm_->Cancel();
1749   ack_queued_ = false;
1750   stop_waiting_count_ = 0;
1751   num_packets_received_since_last_ack_sent_ = 0;
1752
1753   packet_generator_.SetShouldSendAck(true);
1754 }
1755
1756 void QuicConnection::OnRetransmissionTimeout() {
1757   if (!sent_packet_manager_.HasUnackedPackets()) {
1758     return;
1759   }
1760
1761   sent_packet_manager_.OnRetransmissionTimeout();
1762   WriteIfNotBlocked();
1763
1764   // A write failure can result in the connection being closed, don't attempt to
1765   // write further packets, or to set alarms.
1766   if (!connected_) {
1767     return;
1768   }
1769
1770   // In the TLP case, the SentPacketManager gives the connection the opportunity
1771   // to send new data before retransmitting.
1772   if (sent_packet_manager_.MaybeRetransmitTailLossProbe()) {
1773     // Send the pending retransmission now that it's been queued.
1774     WriteIfNotBlocked();
1775   }
1776
1777   // Ensure the retransmission alarm is always set if there are unacked packets
1778   // and nothing waiting to be sent.
1779   if (!HasQueuedData() && !retransmission_alarm_->IsSet()) {
1780     QuicTime rto_timeout = sent_packet_manager_.GetRetransmissionTime();
1781     if (rto_timeout.IsInitialized()) {
1782       retransmission_alarm_->Set(rto_timeout);
1783     }
1784   }
1785 }
1786
1787 void QuicConnection::SetEncrypter(EncryptionLevel level,
1788                                   QuicEncrypter* encrypter) {
1789   packet_generator_.SetEncrypter(level, encrypter);
1790   if (level == ENCRYPTION_FORWARD_SECURE) {
1791     has_forward_secure_encrypter_ = true;
1792     first_required_forward_secure_packet_ =
1793         sequence_number_of_last_sent_packet_ +
1794         // 3 times the current congestion window (in slow start) should cover
1795         // about two full round trips worth of packets, which should be
1796         // sufficient.
1797         3 * sent_packet_manager_.EstimateMaxPacketsInFlight(
1798             max_packet_length());
1799   }
1800 }
1801
1802 void QuicConnection::SetDefaultEncryptionLevel(EncryptionLevel level) {
1803   encryption_level_ = level;
1804   packet_generator_.set_encryption_level(level);
1805 }
1806
1807 void QuicConnection::SetDecrypter(EncryptionLevel level,
1808                                   QuicDecrypter* decrypter) {
1809   framer_.SetDecrypter(level, decrypter);
1810 }
1811
1812 void QuicConnection::SetAlternativeDecrypter(EncryptionLevel level,
1813                                              QuicDecrypter* decrypter,
1814                                              bool latch_once_used) {
1815   framer_.SetAlternativeDecrypter(level, decrypter, latch_once_used);
1816 }
1817
1818 const QuicDecrypter* QuicConnection::decrypter() const {
1819   return framer_.decrypter();
1820 }
1821
1822 const QuicDecrypter* QuicConnection::alternative_decrypter() const {
1823   return framer_.alternative_decrypter();
1824 }
1825
1826 void QuicConnection::QueueUndecryptablePacket(
1827     const QuicEncryptedPacket& packet) {
1828   DVLOG(1) << ENDPOINT << "Queueing undecryptable packet.";
1829   undecryptable_packets_.push_back(packet.Clone());
1830 }
1831
1832 void QuicConnection::MaybeProcessUndecryptablePackets() {
1833   if (undecryptable_packets_.empty() || encryption_level_ == ENCRYPTION_NONE) {
1834     return;
1835   }
1836
1837   while (connected_ && !undecryptable_packets_.empty()) {
1838     DVLOG(1) << ENDPOINT << "Attempting to process undecryptable packet";
1839     QuicEncryptedPacket* packet = undecryptable_packets_.front();
1840     if (!framer_.ProcessPacket(*packet) &&
1841         framer_.error() == QUIC_DECRYPTION_FAILURE) {
1842       DVLOG(1) << ENDPOINT << "Unable to process undecryptable packet...";
1843       break;
1844     }
1845     DVLOG(1) << ENDPOINT << "Processed undecryptable packet!";
1846     ++stats_.packets_processed;
1847     delete packet;
1848     undecryptable_packets_.pop_front();
1849   }
1850
1851   // Once forward secure encryption is in use, there will be no
1852   // new keys installed and hence any undecryptable packets will
1853   // never be able to be decrypted.
1854   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE) {
1855     if (debug_visitor_ != nullptr) {
1856       // TODO(rtenneti): perhaps more efficient to pass the number of
1857       // undecryptable packets as the argument to OnUndecryptablePacket so that
1858       // we just need to call OnUndecryptablePacket once?
1859       for (size_t i = 0; i < undecryptable_packets_.size(); ++i) {
1860         debug_visitor_->OnUndecryptablePacket();
1861       }
1862     }
1863     STLDeleteElements(&undecryptable_packets_);
1864   }
1865 }
1866
1867 void QuicConnection::MaybeProcessRevivedPacket() {
1868   QuicFecGroup* group = GetFecGroup();
1869   if (!connected_ || group == nullptr || !group->CanRevive()) {
1870     return;
1871   }
1872   QuicPacketHeader revived_header;
1873   char revived_payload[kMaxPacketSize];
1874   size_t len = group->Revive(&revived_header, revived_payload, kMaxPacketSize);
1875   revived_header.public_header.connection_id = connection_id_;
1876   revived_header.public_header.connection_id_length =
1877       last_header_.public_header.connection_id_length;
1878   revived_header.public_header.version_flag = false;
1879   revived_header.public_header.reset_flag = false;
1880   revived_header.public_header.sequence_number_length =
1881       last_header_.public_header.sequence_number_length;
1882   revived_header.fec_flag = false;
1883   revived_header.is_in_fec_group = NOT_IN_FEC_GROUP;
1884   revived_header.fec_group = 0;
1885   group_map_.erase(last_header_.fec_group);
1886   last_decrypted_packet_level_ = group->effective_encryption_level();
1887   DCHECK_LT(last_decrypted_packet_level_, NUM_ENCRYPTION_LEVELS);
1888   delete group;
1889
1890   last_packet_revived_ = true;
1891   if (debug_visitor_ != nullptr) {
1892     debug_visitor_->OnRevivedPacket(revived_header,
1893                                     StringPiece(revived_payload, len));
1894   }
1895
1896   ++stats_.packets_revived;
1897   framer_.ProcessRevivedPacket(&revived_header,
1898                                StringPiece(revived_payload, len));
1899 }
1900
1901 QuicFecGroup* QuicConnection::GetFecGroup() {
1902   QuicFecGroupNumber fec_group_num = last_header_.fec_group;
1903   if (fec_group_num == 0) {
1904     return nullptr;
1905   }
1906   if (!ContainsKey(group_map_, fec_group_num)) {
1907     if (group_map_.size() >= kMaxFecGroups) {  // Too many groups
1908       if (fec_group_num < group_map_.begin()->first) {
1909         // The group being requested is a group we've seen before and deleted.
1910         // Don't recreate it.
1911         return nullptr;
1912       }
1913       // Clear the lowest group number.
1914       delete group_map_.begin()->second;
1915       group_map_.erase(group_map_.begin());
1916     }
1917     group_map_[fec_group_num] = new QuicFecGroup();
1918   }
1919   return group_map_[fec_group_num];
1920 }
1921
1922 void QuicConnection::SendConnectionClose(QuicErrorCode error) {
1923   SendConnectionCloseWithDetails(error, string());
1924 }
1925
1926 void QuicConnection::SendConnectionCloseWithDetails(QuicErrorCode error,
1927                                                     const string& details) {
1928   // If we're write blocked, WritePacket() will not send, but will capture the
1929   // serialized packet.
1930   SendConnectionClosePacket(error, details);
1931   CloseConnection(error, false);
1932 }
1933
1934 void QuicConnection::SendConnectionClosePacket(QuicErrorCode error,
1935                                                const string& details) {
1936   DVLOG(1) << ENDPOINT << "Force closing " << connection_id()
1937            << " with error " << QuicUtils::ErrorToString(error)
1938            << " (" << error << ") " << details;
1939   // Don't send explicit connection close packets for timeouts.
1940   // This is particularly important on mobile, where connections are short.
1941   if (silent_close_enabled_ &&
1942       error == QuicErrorCode::QUIC_CONNECTION_TIMED_OUT) {
1943     return;
1944   }
1945   ScopedPacketBundler ack_bundler(this, SEND_ACK);
1946   QuicConnectionCloseFrame* frame = new QuicConnectionCloseFrame();
1947   frame->error_code = error;
1948   frame->error_details = details;
1949   packet_generator_.AddControlFrame(QuicFrame(frame));
1950   packet_generator_.FlushAllQueuedFrames();
1951 }
1952
1953 void QuicConnection::CloseConnection(QuicErrorCode error, bool from_peer) {
1954   if (!connected_) {
1955     DVLOG(1) << "Connection is already closed.";
1956     return;
1957   }
1958   connected_ = false;
1959   if (debug_visitor_ != nullptr) {
1960     debug_visitor_->OnConnectionClosed(error, from_peer);
1961   }
1962   DCHECK(visitor_ != nullptr);
1963   visitor_->OnConnectionClosed(error, from_peer);
1964   // Cancel the alarms so they don't trigger any action now that the
1965   // connection is closed.
1966   ack_alarm_->Cancel();
1967   ping_alarm_->Cancel();
1968   fec_alarm_->Cancel();
1969   resume_writes_alarm_->Cancel();
1970   retransmission_alarm_->Cancel();
1971   send_alarm_->Cancel();
1972   timeout_alarm_->Cancel();
1973 }
1974
1975 void QuicConnection::SendGoAway(QuicErrorCode error,
1976                                 QuicStreamId last_good_stream_id,
1977                                 const string& reason) {
1978   DVLOG(1) << ENDPOINT << "Going away with error "
1979            << QuicUtils::ErrorToString(error)
1980            << " (" << error << ")";
1981
1982   // Opportunistically bundle an ack with this outgoing packet.
1983   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1984   packet_generator_.AddControlFrame(
1985       QuicFrame(new QuicGoAwayFrame(error, last_good_stream_id, reason)));
1986 }
1987
1988 void QuicConnection::CloseFecGroupsBefore(
1989     QuicPacketSequenceNumber sequence_number) {
1990   FecGroupMap::iterator it = group_map_.begin();
1991   while (it != group_map_.end()) {
1992     // If this is the current group or the group doesn't protect this packet
1993     // we can ignore it.
1994     if (last_header_.fec_group == it->first ||
1995         !it->second->ProtectsPacketsBefore(sequence_number)) {
1996       ++it;
1997       continue;
1998     }
1999     QuicFecGroup* fec_group = it->second;
2000     DCHECK(!fec_group->CanRevive());
2001     FecGroupMap::iterator next = it;
2002     ++next;
2003     group_map_.erase(it);
2004     delete fec_group;
2005     it = next;
2006   }
2007 }
2008
2009 QuicByteCount QuicConnection::max_packet_length() const {
2010   return packet_generator_.GetMaxPacketLength();
2011 }
2012
2013 void QuicConnection::set_max_packet_length(QuicByteCount length) {
2014   return packet_generator_.SetMaxPacketLength(length, /*force=*/false);
2015 }
2016
2017 bool QuicConnection::HasQueuedData() const {
2018   return pending_version_negotiation_packet_ ||
2019       !queued_packets_.empty() || packet_generator_.HasQueuedFrames();
2020 }
2021
2022 bool QuicConnection::CanWriteStreamData() {
2023   // Don't write stream data if there are negotiation or queued data packets
2024   // to send. Otherwise, continue and bundle as many frames as possible.
2025   if (pending_version_negotiation_packet_ || !queued_packets_.empty()) {
2026     return false;
2027   }
2028
2029   IsHandshake pending_handshake = visitor_->HasPendingHandshake() ?
2030       IS_HANDSHAKE : NOT_HANDSHAKE;
2031   // Sending queued packets may have caused the socket to become write blocked,
2032   // or the congestion manager to prohibit sending.  If we've sent everything
2033   // we had queued and we're still not blocked, let the visitor know it can
2034   // write more.
2035   return ShouldGeneratePacket(HAS_RETRANSMITTABLE_DATA, pending_handshake);
2036 }
2037
2038 void QuicConnection::SetNetworkTimeouts(QuicTime::Delta overall_timeout,
2039                                         QuicTime::Delta idle_timeout) {
2040   LOG_IF(DFATAL, idle_timeout > overall_timeout)
2041       << "idle_timeout:" << idle_timeout.ToMilliseconds()
2042       << " overall_timeout:" << overall_timeout.ToMilliseconds();
2043   // Adjust the idle timeout on client and server to prevent clients from
2044   // sending requests to servers which have already closed the connection.
2045   if (perspective_ == Perspective::IS_SERVER) {
2046     idle_timeout = idle_timeout.Add(QuicTime::Delta::FromSeconds(3));
2047   } else if (idle_timeout > QuicTime::Delta::FromSeconds(1)) {
2048     idle_timeout = idle_timeout.Subtract(QuicTime::Delta::FromSeconds(1));
2049   }
2050   overall_connection_timeout_ = overall_timeout;
2051   idle_network_timeout_ = idle_timeout;
2052
2053   SetTimeoutAlarm();
2054 }
2055
2056 void QuicConnection::CheckForTimeout() {
2057   QuicTime now = clock_->ApproximateNow();
2058   QuicTime time_of_last_packet = max(time_of_last_received_packet_,
2059                                      time_of_last_sent_new_packet_);
2060
2061   // |delta| can be < 0 as |now| is approximate time but |time_of_last_packet|
2062   // is accurate time. However, this should not change the behavior of
2063   // timeout handling.
2064   QuicTime::Delta idle_duration = now.Subtract(time_of_last_packet);
2065   DVLOG(1) << ENDPOINT << "last packet "
2066            << time_of_last_packet.ToDebuggingValue()
2067            << " now:" << now.ToDebuggingValue()
2068            << " idle_duration:" << idle_duration.ToMicroseconds()
2069            << " idle_network_timeout: "
2070            << idle_network_timeout_.ToMicroseconds();
2071   if (idle_duration >= idle_network_timeout_) {
2072     DVLOG(1) << ENDPOINT << "Connection timedout due to no network activity.";
2073     SendConnectionClose(QUIC_CONNECTION_TIMED_OUT);
2074     return;
2075   }
2076
2077   if (!overall_connection_timeout_.IsInfinite()) {
2078     QuicTime::Delta connected_duration =
2079         now.Subtract(stats_.connection_creation_time);
2080     DVLOG(1) << ENDPOINT << "connection time: "
2081              << connected_duration.ToMicroseconds() << " overall timeout: "
2082              << overall_connection_timeout_.ToMicroseconds();
2083     if (connected_duration >= overall_connection_timeout_) {
2084       DVLOG(1) << ENDPOINT <<
2085           "Connection timedout due to overall connection timeout.";
2086       SendConnectionClose(QUIC_CONNECTION_OVERALL_TIMED_OUT);
2087       return;
2088     }
2089   }
2090
2091   SetTimeoutAlarm();
2092 }
2093
2094 void QuicConnection::SetTimeoutAlarm() {
2095   QuicTime time_of_last_packet = max(time_of_last_received_packet_,
2096                                      time_of_last_sent_new_packet_);
2097
2098   QuicTime deadline = time_of_last_packet.Add(idle_network_timeout_);
2099   if (!overall_connection_timeout_.IsInfinite()) {
2100     deadline = min(deadline,
2101                    stats_.connection_creation_time.Add(
2102                        overall_connection_timeout_));
2103   }
2104
2105   timeout_alarm_->Cancel();
2106   timeout_alarm_->Set(deadline);
2107 }
2108
2109 void QuicConnection::SetPingAlarm() {
2110   if (perspective_ == Perspective::IS_SERVER) {
2111     // Only clients send pings.
2112     return;
2113   }
2114   if (!visitor_->HasOpenDynamicStreams()) {
2115     ping_alarm_->Cancel();
2116     // Don't send a ping unless there are open streams.
2117     return;
2118   }
2119   QuicTime::Delta ping_timeout = QuicTime::Delta::FromSeconds(kPingTimeoutSecs);
2120   ping_alarm_->Update(clock_->ApproximateNow().Add(ping_timeout),
2121                       QuicTime::Delta::FromSeconds(1));
2122 }
2123
2124 QuicConnection::ScopedPacketBundler::ScopedPacketBundler(
2125     QuicConnection* connection,
2126     AckBundling send_ack)
2127     : connection_(connection),
2128       already_in_batch_mode_(connection != nullptr &&
2129                              connection->packet_generator_.InBatchMode()) {
2130   if (connection_ == nullptr) {
2131     return;
2132   }
2133   // Move generator into batch mode. If caller wants us to include an ack,
2134   // check the delayed-ack timer to see if there's ack info to be sent.
2135   if (!already_in_batch_mode_) {
2136     DVLOG(1) << "Entering Batch Mode.";
2137     connection_->packet_generator_.StartBatchOperations();
2138   }
2139   // Bundle an ack if the alarm is set or with every second packet if we need to
2140   // raise the peer's least unacked.
2141   bool ack_pending =
2142       connection_->ack_alarm_->IsSet() || connection_->stop_waiting_count_ > 1;
2143   if (send_ack == SEND_ACK || (send_ack == BUNDLE_PENDING_ACK && ack_pending)) {
2144     DVLOG(1) << "Bundling ack with outgoing packet.";
2145     connection_->SendAck();
2146   }
2147 }
2148
2149 QuicConnection::ScopedPacketBundler::~ScopedPacketBundler() {
2150   if (connection_ == nullptr) {
2151     return;
2152   }
2153   // If we changed the generator's batch state, restore original batch state.
2154   if (!already_in_batch_mode_) {
2155     DVLOG(1) << "Leaving Batch Mode.";
2156     connection_->packet_generator_.FinishBatchOperations();
2157   }
2158   DCHECK_EQ(already_in_batch_mode_,
2159             connection_->packet_generator_.InBatchMode());
2160 }
2161
2162 HasRetransmittableData QuicConnection::IsRetransmittable(
2163     const QueuedPacket& packet) {
2164   // Retransmitted packets retransmittable frames are owned by the unacked
2165   // packet map, but are not present in the serialized packet.
2166   if (packet.transmission_type != NOT_RETRANSMISSION ||
2167       packet.serialized_packet.retransmittable_frames != nullptr) {
2168     return HAS_RETRANSMITTABLE_DATA;
2169   } else {
2170     return NO_RETRANSMITTABLE_DATA;
2171   }
2172 }
2173
2174 bool QuicConnection::IsConnectionClose(const QueuedPacket& packet) {
2175   const RetransmittableFrames* retransmittable_frames =
2176       packet.serialized_packet.retransmittable_frames;
2177   if (retransmittable_frames == nullptr) {
2178     return false;
2179   }
2180   for (const QuicFrame& frame : retransmittable_frames->frames()) {
2181     if (frame.type == CONNECTION_CLOSE_FRAME) {
2182       return true;
2183     }
2184   }
2185   return false;
2186 }
2187
2188 }  // namespace net