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