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