src/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 #include <algorithm>
  10 #include <iterator>
  11 #include <limits>
  12 #include <memory>
  13 #include <set>
  14 #include <utility>
  15
  16 #include "base/debug/stack_trace.h"
  17 #include "base/logging.h"
  18 #include "base/stl_util.h"
  19 #include "net/base/net_errors.h"
  20 #include "net/quic/crypto/quic_decrypter.h"
  21 #include "net/quic/crypto/quic_encrypter.h"
  22 #include "net/quic/iovector.h"
  23 #include "net/quic/quic_bandwidth.h"
  24 #include "net/quic/quic_config.h"
  25 #include "net/quic/quic_utils.h"
  26
  27 using base::hash_map;
  28 using base::hash_set;
  29 using base::StringPiece;
  30 using std::list;
  31 using std::make_pair;
  32 using std::min;
  33 using std::max;
  34 using std::numeric_limits;
  35 using std::vector;
  36 using std::set;
  37 using std::string;
  38
  39 extern bool FLAGS_quic_allow_oversized_packets_for_test;
  40
  41 namespace net {
  42
  43 class QuicDecrypter;
  44 class QuicEncrypter;
  45
  46 namespace {
  47
  48 // The largest gap in packets we'll accept without closing the connection.
  49 // This will likely have to be tuned.
  50 const QuicPacketSequenceNumber kMaxPacketGap = 5000;
  51
  52 // Limit the number of FEC groups to two.  If we get enough out of order packets
  53 // that this becomes limiting, we can revisit.
  54 const size_t kMaxFecGroups = 2;
  55
  56 // Limit the number of undecryptable packets we buffer in
  57 // expectation of the CHLO/SHLO arriving.
  58 const size_t kMaxUndecryptablePackets = 10;
  59
  60 bool Near(QuicPacketSequenceNumber a, QuicPacketSequenceNumber b) {
  61   QuicPacketSequenceNumber delta = (a > b) ? a - b : b - a;
  62   return delta <= kMaxPacketGap;
  63 }
  64
  65 // An alarm that is scheduled to send an ack if a timeout occurs.
  66 class AckAlarm : public QuicAlarm::Delegate {
  67  public:
  68   explicit AckAlarm(QuicConnection* connection)
  69       : connection_(connection) {
  70   }
  71
  72   virtual QuicTime OnAlarm() OVERRIDE {
  73     connection_->SendAck();
  74     return QuicTime::Zero();
  75   }
  76
  77  private:
  78   QuicConnection* connection_;
  79 };
  80
  81 // This alarm will be scheduled any time a data-bearing packet is sent out.
  82 // When the alarm goes off, the connection checks to see if the oldest packets
  83 // have been acked, and retransmit them if they have not.
  84 class RetransmissionAlarm : public QuicAlarm::Delegate {
  85  public:
  86   explicit RetransmissionAlarm(QuicConnection* connection)
  87       : connection_(connection) {
  88   }
  89
  90   virtual QuicTime OnAlarm() OVERRIDE {
  91     connection_->OnRetransmissionTimeout();
  92     return QuicTime::Zero();
  93   }
  94
  95  private:
  96   QuicConnection* connection_;
  97 };
  98
  99 // An alarm that is scheduled when the sent scheduler requires a
 100 // a delay before sending packets and fires when the packet may be sent.
 101 class SendAlarm : public QuicAlarm::Delegate {
 102  public:
 103   explicit SendAlarm(QuicConnection* connection)
 104       : connection_(connection) {
 105   }
 106
 107   virtual QuicTime OnAlarm() OVERRIDE {
 108     connection_->WriteIfNotBlocked();
 109     // Never reschedule the alarm, since CanWrite does that.
 110     return QuicTime::Zero();
 111   }
 112
 113  private:
 114   QuicConnection* connection_;
 115 };
 116
 117 class TimeoutAlarm : public QuicAlarm::Delegate {
 118  public:
 119   explicit TimeoutAlarm(QuicConnection* connection)
 120       : connection_(connection) {
 121   }
 122
 123   virtual QuicTime OnAlarm() OVERRIDE {
 124     connection_->CheckForTimeout();
 125     // Never reschedule the alarm, since CheckForTimeout does that.
 126     return QuicTime::Zero();
 127   }
 128
 129  private:
 130   QuicConnection* connection_;
 131 };
 132
 133 QuicConnection::PacketType GetPacketType(
 134     const RetransmittableFrames* retransmittable_frames) {
 135   if (!retransmittable_frames) {
 136     return QuicConnection::NORMAL;
 137   }
 138   for (size_t i = 0; i < retransmittable_frames->frames().size(); ++i) {
 139     if (retransmittable_frames->frames()[i].type == CONNECTION_CLOSE_FRAME) {
 140       return QuicConnection::CONNECTION_CLOSE;
 141     }
 142   }
 143   return QuicConnection::NORMAL;
 144 }
 145
 146 }  // namespace
 147
 148 QuicConnection::QueuedPacket::QueuedPacket(SerializedPacket packet,
 149                                            EncryptionLevel level,
 150                                            TransmissionType transmission_type)
 151   : sequence_number(packet.sequence_number),
 152     packet(packet.packet),
 153     encryption_level(level),
 154     transmission_type(transmission_type),
 155     retransmittable((transmission_type != NOT_RETRANSMISSION ||
 156                      packet.retransmittable_frames != NULL) ?
 157                          HAS_RETRANSMITTABLE_DATA : NO_RETRANSMITTABLE_DATA),
 158     handshake(packet.retransmittable_frames == NULL ?
 159       NOT_HANDSHAKE : packet.retransmittable_frames->HasCryptoHandshake()),
 160     type(GetPacketType(packet.retransmittable_frames)),
 161     length(packet.packet->length()) {
 162 }
 163
 164 #define ENDPOINT (is_server_ ? "Server: " : " Client: ")
 165
 166 QuicConnection::QuicConnection(QuicConnectionId connection_id,
 167                                IPEndPoint address,
 168                                QuicConnectionHelperInterface* helper,
 169                                QuicPacketWriter* writer,
 170                                bool is_server,
 171                                const QuicVersionVector& supported_versions)
 172     : framer_(supported_versions,
 173               helper->GetClock()->ApproximateNow(),
 174               is_server),
 175       helper_(helper),
 176       writer_(writer),
 177       encryption_level_(ENCRYPTION_NONE),
 178       clock_(helper->GetClock()),
 179       random_generator_(helper->GetRandomGenerator()),
 180       connection_id_(connection_id),
 181       peer_address_(address),
 182       largest_seen_packet_with_ack_(0),
 183       largest_seen_packet_with_stop_waiting_(0),
 184       pending_version_negotiation_packet_(false),
 185       received_packet_manager_(kTCP),
 186       ack_queued_(false),
 187       stop_waiting_count_(0),
 188       ack_alarm_(helper->CreateAlarm(new AckAlarm(this))),
 189       retransmission_alarm_(helper->CreateAlarm(new RetransmissionAlarm(this))),
 190       send_alarm_(helper->CreateAlarm(new SendAlarm(this))),
 191       resume_writes_alarm_(helper->CreateAlarm(new SendAlarm(this))),
 192       timeout_alarm_(helper->CreateAlarm(new TimeoutAlarm(this))),
 193       debug_visitor_(NULL),
 194       packet_creator_(connection_id_, &framer_, random_generator_, is_server),
 195       packet_generator_(this, NULL, &packet_creator_),
 196       idle_network_timeout_(
 197           QuicTime::Delta::FromSeconds(kDefaultInitialTimeoutSecs)),
 198       overall_connection_timeout_(QuicTime::Delta::Infinite()),
 199       creation_time_(clock_->ApproximateNow()),
 200       time_of_last_received_packet_(clock_->ApproximateNow()),
 201       time_of_last_sent_new_packet_(clock_->ApproximateNow()),
 202       sequence_number_of_last_sent_packet_(0),
 203       sent_packet_manager_(is_server, clock_, &stats_, kTCP),
 204       version_negotiation_state_(START_NEGOTIATION),
 205       is_server_(is_server),
 206       connected_(true),
 207       address_migrating_(false) {
 208   if (!is_server_) {
 209     // Pacing will be enabled if the client negotiates it.
 210     sent_packet_manager_.MaybeEnablePacing();
 211   }
 212   DVLOG(1) << ENDPOINT << "Created connection with connection_id: "
 213            << connection_id;
 214   timeout_alarm_->Set(clock_->ApproximateNow().Add(idle_network_timeout_));
 215   framer_.set_visitor(this);
 216   framer_.set_received_entropy_calculator(&received_packet_manager_);
 217 }
 218
 219 QuicConnection::~QuicConnection() {
 220   STLDeleteElements(&undecryptable_packets_);
 221   STLDeleteValues(&group_map_);
 222   for (QueuedPacketList::iterator it = queued_packets_.begin();
 223        it != queued_packets_.end(); ++it) {
 224     delete it->packet;
 225   }
 226 }
 227
 228 void QuicConnection::SetFromConfig(const QuicConfig& config) {
 229   DCHECK_LT(0u, config.server_initial_congestion_window());
 230   SetIdleNetworkTimeout(config.idle_connection_state_lifetime());
 231   sent_packet_manager_.SetFromConfig(config);
 232   // TODO(satyamshekhar): Set congestion control and ICSL also.
 233 }
 234
 235 bool QuicConnection::SelectMutualVersion(
 236     const QuicVersionVector& available_versions) {
 237   // Try to find the highest mutual version by iterating over supported
 238   // versions, starting with the highest, and breaking out of the loop once we
 239   // find a matching version in the provided available_versions vector.
 240   const QuicVersionVector& supported_versions = framer_.supported_versions();
 241   for (size_t i = 0; i < supported_versions.size(); ++i) {
 242     const QuicVersion& version = supported_versions[i];
 243     if (std::find(available_versions.begin(), available_versions.end(),
 244                   version) != available_versions.end()) {
 245       framer_.set_version(version);
 246       return true;
 247     }
 248   }
 249
 250   return false;
 251 }
 252
 253 void QuicConnection::OnError(QuicFramer* framer) {
 254   // Packets that we cannot decrypt are dropped.
 255   // TODO(rch): add stats to measure this.
 256   if (!connected_ || framer->error() == QUIC_DECRYPTION_FAILURE) {
 257     return;
 258   }
 259   SendConnectionCloseWithDetails(framer->error(), framer->detailed_error());
 260 }
 261
 262 void QuicConnection::OnPacket() {
 263   DCHECK(last_stream_frames_.empty() &&
 264          last_goaway_frames_.empty() &&
 265          last_window_update_frames_.empty() &&
 266          last_blocked_frames_.empty() &&
 267          last_rst_frames_.empty() &&
 268          last_ack_frames_.empty() &&
 269          last_congestion_frames_.empty() &&
 270          last_stop_waiting_frames_.empty());
 271 }
 272
 273 void QuicConnection::OnPublicResetPacket(
 274     const QuicPublicResetPacket& packet) {
 275   if (debug_visitor_) {
 276     debug_visitor_->OnPublicResetPacket(packet);
 277   }
 278   CloseConnection(QUIC_PUBLIC_RESET, true);
 279 }
 280
 281 bool QuicConnection::OnProtocolVersionMismatch(QuicVersion received_version) {
 282   DVLOG(1) << ENDPOINT << "Received packet with mismatched version "
 283            << received_version;
 284   // TODO(satyamshekhar): Implement no server state in this mode.
 285   if (!is_server_) {
 286     LOG(DFATAL) << ENDPOINT << "Framer called OnProtocolVersionMismatch. "
 287                 << "Closing connection.";
 288     CloseConnection(QUIC_INTERNAL_ERROR, false);
 289     return false;
 290   }
 291   DCHECK_NE(version(), received_version);
 292
 293   if (debug_visitor_) {
 294     debug_visitor_->OnProtocolVersionMismatch(received_version);
 295   }
 296
 297   switch (version_negotiation_state_) {
 298     case START_NEGOTIATION:
 299       if (!framer_.IsSupportedVersion(received_version)) {
 300         SendVersionNegotiationPacket();
 301         version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
 302         return false;
 303       }
 304       break;
 305
 306     case NEGOTIATION_IN_PROGRESS:
 307       if (!framer_.IsSupportedVersion(received_version)) {
 308         SendVersionNegotiationPacket();
 309         return false;
 310       }
 311       break;
 312
 313     case NEGOTIATED_VERSION:
 314       // Might be old packets that were sent by the client before the version
 315       // was negotiated. Drop these.
 316       return false;
 317
 318     default:
 319       DCHECK(false);
 320   }
 321
 322   version_negotiation_state_ = NEGOTIATED_VERSION;
 323   visitor_->OnSuccessfulVersionNegotiation(received_version);
 324   DVLOG(1) << ENDPOINT << "version negotiated " << received_version;
 325
 326   // Store the new version.
 327   framer_.set_version(received_version);
 328
 329   // TODO(satyamshekhar): Store the sequence number of this packet and close the
 330   // connection if we ever received a packet with incorrect version and whose
 331   // sequence number is greater.
 332   return true;
 333 }
 334
 335 // Handles version negotiation for client connection.
 336 void QuicConnection::OnVersionNegotiationPacket(
 337     const QuicVersionNegotiationPacket& packet) {
 338   if (is_server_) {
 339     LOG(DFATAL) << ENDPOINT << "Framer parsed VersionNegotiationPacket."
 340                 << " Closing connection.";
 341     CloseConnection(QUIC_INTERNAL_ERROR, false);
 342     return;
 343   }
 344   if (debug_visitor_) {
 345     debug_visitor_->OnVersionNegotiationPacket(packet);
 346   }
 347
 348   if (version_negotiation_state_ != START_NEGOTIATION) {
 349     // Possibly a duplicate version negotiation packet.
 350     return;
 351   }
 352
 353   if (std::find(packet.versions.begin(),
 354                 packet.versions.end(), version()) !=
 355       packet.versions.end()) {
 356     DLOG(WARNING) << ENDPOINT << "The server already supports our version. "
 357                   << "It should have accepted our connection.";
 358     // Just drop the connection.
 359     CloseConnection(QUIC_INVALID_VERSION_NEGOTIATION_PACKET, false);
 360     return;
 361   }
 362
 363   if (!SelectMutualVersion(packet.versions)) {
 364     SendConnectionCloseWithDetails(QUIC_INVALID_VERSION,
 365                                    "no common version found");
 366     return;
 367   }
 368
 369   DVLOG(1) << ENDPOINT << "negotiating version " << version();
 370   server_supported_versions_ = packet.versions;
 371   version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
 372   RetransmitUnackedPackets(ALL_PACKETS);
 373 }
 374
 375 void QuicConnection::OnRevivedPacket() {
 376 }
 377
 378 bool QuicConnection::OnUnauthenticatedPublicHeader(
 379     const QuicPacketPublicHeader& header) {
 380   return true;
 381 }
 382
 383 bool QuicConnection::OnUnauthenticatedHeader(const QuicPacketHeader& header) {
 384   return true;
 385 }
 386
 387 bool QuicConnection::OnPacketHeader(const QuicPacketHeader& header) {
 388   if (debug_visitor_) {
 389     debug_visitor_->OnPacketHeader(header);
 390   }
 391
 392   if (header.fec_flag && framer_.version() == QUIC_VERSION_13) {
 393     return false;
 394   }
 395
 396   if (!ProcessValidatedPacket()) {
 397     return false;
 398   }
 399
 400   // Will be decrement below if we fall through to return true;
 401   ++stats_.packets_dropped;
 402
 403   if (header.public_header.connection_id != connection_id_) {
 404     DVLOG(1) << ENDPOINT << "Ignoring packet from unexpected ConnectionId: "
 405              << header.public_header.connection_id << " instead of "
 406              << connection_id_;
 407     return false;
 408   }
 409
 410   if (!Near(header.packet_sequence_number,
 411             last_header_.packet_sequence_number)) {
 412     DVLOG(1) << ENDPOINT << "Packet " << header.packet_sequence_number
 413              << " out of bounds.  Discarding";
 414     SendConnectionCloseWithDetails(QUIC_INVALID_PACKET_HEADER,
 415                                    "Packet sequence number out of bounds");
 416     return false;
 417   }
 418
 419   // If this packet has already been seen, or that the sender
 420   // has told us will not be retransmitted, then stop processing the packet.
 421   if (!received_packet_manager_.IsAwaitingPacket(
 422           header.packet_sequence_number)) {
 423     return false;
 424   }
 425
 426   if (version_negotiation_state_ != NEGOTIATED_VERSION) {
 427     if (is_server_) {
 428       if (!header.public_header.version_flag) {
 429         DLOG(WARNING) << ENDPOINT << "Got packet without version flag before "
 430                       << "version negotiated.";
 431         // Packets should have the version flag till version negotiation is
 432         // done.
 433         CloseConnection(QUIC_INVALID_VERSION, false);
 434         return false;
 435       } else {
 436         DCHECK_EQ(1u, header.public_header.versions.size());
 437         DCHECK_EQ(header.public_header.versions[0], version());
 438         version_negotiation_state_ = NEGOTIATED_VERSION;
 439         visitor_->OnSuccessfulVersionNegotiation(version());
 440       }
 441     } else {
 442       DCHECK(!header.public_header.version_flag);
 443       // If the client gets a packet without the version flag from the server
 444       // it should stop sending version since the version negotiation is done.
 445       packet_creator_.StopSendingVersion();
 446       version_negotiation_state_ = NEGOTIATED_VERSION;
 447       visitor_->OnSuccessfulVersionNegotiation(version());
 448     }
 449   }
 450
 451   DCHECK_EQ(NEGOTIATED_VERSION, version_negotiation_state_);
 452
 453   --stats_.packets_dropped;
 454   DVLOG(1) << ENDPOINT << "Received packet header: " << header;
 455   last_header_ = header;
 456   DCHECK(connected_);
 457   return true;
 458 }
 459
 460 void QuicConnection::OnFecProtectedPayload(StringPiece payload) {
 461   DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
 462   DCHECK_NE(0u, last_header_.fec_group);
 463   QuicFecGroup* group = GetFecGroup();
 464   if (group != NULL) {
 465     group->Update(last_header_, payload);
 466   }
 467 }
 468
 469 bool QuicConnection::OnStreamFrame(const QuicStreamFrame& frame) {
 470   DCHECK(connected_);
 471   if (debug_visitor_) {
 472     debug_visitor_->OnStreamFrame(frame);
 473   }
 474   last_stream_frames_.push_back(frame);
 475   return true;
 476 }
 477
 478 bool QuicConnection::OnAckFrame(const QuicAckFrame& incoming_ack) {
 479   DCHECK(connected_);
 480   if (debug_visitor_) {
 481     debug_visitor_->OnAckFrame(incoming_ack);
 482   }
 483   DVLOG(1) << ENDPOINT << "OnAckFrame: " << incoming_ack;
 484
 485   if (last_header_.packet_sequence_number <= largest_seen_packet_with_ack_) {
 486     DVLOG(1) << ENDPOINT << "Received an old ack frame: ignoring";
 487     return true;
 488   }
 489
 490   if (!ValidateAckFrame(incoming_ack)) {
 491     SendConnectionClose(QUIC_INVALID_ACK_DATA);
 492     return false;
 493   }
 494
 495   last_ack_frames_.push_back(incoming_ack);
 496   return connected_;
 497 }
 498
 499 void QuicConnection::ProcessAckFrame(const QuicAckFrame& incoming_ack) {
 500   largest_seen_packet_with_ack_ = last_header_.packet_sequence_number;
 501   received_packet_manager_.UpdatePacketInformationReceivedByPeer(
 502       incoming_ack.received_info);
 503   if (version() <= QUIC_VERSION_15) {
 504     ProcessStopWaitingFrame(incoming_ack.sent_info);
 505   }
 506
 507   sent_entropy_manager_.ClearEntropyBefore(
 508       received_packet_manager_.least_packet_awaited_by_peer() - 1);
 509
 510   bool reset_retransmission_alarm =
 511       sent_packet_manager_.OnIncomingAck(incoming_ack.received_info,
 512                                          time_of_last_received_packet_);
 513   if (sent_packet_manager_.HasPendingRetransmissions()) {
 514     WriteIfNotBlocked();
 515   }
 516
 517   if (reset_retransmission_alarm) {
 518     retransmission_alarm_->Cancel();
 519     QuicTime retransmission_time =
 520         sent_packet_manager_.GetRetransmissionTime();
 521     if (retransmission_time != QuicTime::Zero()) {
 522       retransmission_alarm_->Set(retransmission_time);
 523     }
 524   }
 525 }
 526
 527 void QuicConnection::ProcessStopWaitingFrame(
 528     const QuicStopWaitingFrame& stop_waiting) {
 529   largest_seen_packet_with_stop_waiting_ = last_header_.packet_sequence_number;
 530   received_packet_manager_.UpdatePacketInformationSentByPeer(stop_waiting);
 531   // Possibly close any FecGroups which are now irrelevant.
 532   CloseFecGroupsBefore(stop_waiting.least_unacked + 1);
 533 }
 534
 535 bool QuicConnection::OnCongestionFeedbackFrame(
 536     const QuicCongestionFeedbackFrame& feedback) {
 537   DCHECK(connected_);
 538   if (debug_visitor_) {
 539     debug_visitor_->OnCongestionFeedbackFrame(feedback);
 540   }
 541   last_congestion_frames_.push_back(feedback);
 542   return connected_;
 543 }
 544
 545 bool QuicConnection::OnStopWaitingFrame(const QuicStopWaitingFrame& frame) {
 546   DCHECK(connected_);
 547
 548   if (last_header_.packet_sequence_number <=
 549       largest_seen_packet_with_stop_waiting_) {
 550     DVLOG(1) << ENDPOINT << "Received an old stop waiting frame: ignoring";
 551     return true;
 552   }
 553
 554   if (!ValidateStopWaitingFrame(frame)) {
 555     SendConnectionClose(QUIC_INVALID_STOP_WAITING_DATA);
 556     return false;
 557   }
 558
 559   if (debug_visitor_) {
 560     debug_visitor_->OnStopWaitingFrame(frame);
 561   }
 562
 563   last_stop_waiting_frames_.push_back(frame);
 564   return connected_;
 565 }
 566
 567 bool QuicConnection::ValidateAckFrame(const QuicAckFrame& incoming_ack) {
 568   if (incoming_ack.received_info.largest_observed >
 569       packet_creator_.sequence_number()) {
 570     DLOG(ERROR) << ENDPOINT << "Peer's observed unsent packet:"
 571                 << incoming_ack.received_info.largest_observed << " vs "
 572                 << packet_creator_.sequence_number();
 573     // We got an error for data we have not sent.  Error out.
 574     return false;
 575   }
 576
 577   if (incoming_ack.received_info.largest_observed <
 578           received_packet_manager_.peer_largest_observed_packet()) {
 579     DLOG(ERROR) << ENDPOINT << "Peer's largest_observed packet decreased:"
 580                 << incoming_ack.received_info.largest_observed << " vs "
 581                 << received_packet_manager_.peer_largest_observed_packet();
 582     // A new ack has a diminished largest_observed value.  Error out.
 583     // If this was an old packet, we wouldn't even have checked.
 584     return false;
 585   }
 586
 587   if (version() <= QUIC_VERSION_15) {
 588     if (!ValidateStopWaitingFrame(incoming_ack.sent_info)) {
 589       return false;
 590     }
 591   }
 592
 593   if (!incoming_ack.received_info.missing_packets.empty() &&
 594       *incoming_ack.received_info.missing_packets.rbegin() >
 595       incoming_ack.received_info.largest_observed) {
 596     DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
 597                 << *incoming_ack.received_info.missing_packets.rbegin()
 598                 << " which is greater than largest observed: "
 599                 << incoming_ack.received_info.largest_observed;
 600     return false;
 601   }
 602
 603   if (!incoming_ack.received_info.missing_packets.empty() &&
 604       *incoming_ack.received_info.missing_packets.begin() <
 605       received_packet_manager_.least_packet_awaited_by_peer()) {
 606     DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
 607                 << *incoming_ack.received_info.missing_packets.begin()
 608                 << " which is smaller than least_packet_awaited_by_peer_: "
 609                 << received_packet_manager_.least_packet_awaited_by_peer();
 610     return false;
 611   }
 612
 613   if (!sent_entropy_manager_.IsValidEntropy(
 614           incoming_ack.received_info.largest_observed,
 615           incoming_ack.received_info.missing_packets,
 616           incoming_ack.received_info.entropy_hash)) {
 617     DLOG(ERROR) << ENDPOINT << "Peer sent invalid entropy.";
 618     return false;
 619   }
 620
 621   for (SequenceNumberSet::const_iterator iter =
 622            incoming_ack.received_info.revived_packets.begin();
 623        iter != incoming_ack.received_info.revived_packets.end(); ++iter) {
 624     if (!ContainsKey(incoming_ack.received_info.missing_packets, *iter)) {
 625       DLOG(ERROR) << ENDPOINT
 626                   << "Peer specified revived packet which was not missing.";
 627       return false;
 628     }
 629   }
 630   return true;
 631 }
 632
 633 bool QuicConnection::ValidateStopWaitingFrame(
 634     const QuicStopWaitingFrame& stop_waiting) {
 635   if (stop_waiting.least_unacked <
 636       received_packet_manager_.peer_least_packet_awaiting_ack()) {
 637     DLOG(ERROR) << ENDPOINT << "Peer's sent low least_unacked: "
 638                 << stop_waiting.least_unacked << " vs "
 639                 << received_packet_manager_.peer_least_packet_awaiting_ack();
 640     // We never process old ack frames, so this number should only increase.
 641     return false;
 642   }
 643
 644   if (stop_waiting.least_unacked >
 645       last_header_.packet_sequence_number) {
 646     DLOG(ERROR) << ENDPOINT << "Peer sent least_unacked:"
 647                 << stop_waiting.least_unacked
 648                 << " greater than the enclosing packet sequence number:"
 649                 << last_header_.packet_sequence_number;
 650     return false;
 651   }
 652
 653   return true;
 654 }
 655
 656 void QuicConnection::OnFecData(const QuicFecData& fec) {
 657   DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
 658   DCHECK_NE(0u, last_header_.fec_group);
 659   QuicFecGroup* group = GetFecGroup();
 660   if (group != NULL) {
 661     group->UpdateFec(last_header_.packet_sequence_number, fec);
 662   }
 663 }
 664
 665 bool QuicConnection::OnRstStreamFrame(const QuicRstStreamFrame& frame) {
 666   DCHECK(connected_);
 667   if (debug_visitor_) {
 668     debug_visitor_->OnRstStreamFrame(frame);
 669   }
 670   DVLOG(1) << ENDPOINT << "Stream reset with error "
 671            << QuicUtils::StreamErrorToString(frame.error_code);
 672   last_rst_frames_.push_back(frame);
 673   return connected_;
 674 }
 675
 676 bool QuicConnection::OnConnectionCloseFrame(
 677     const QuicConnectionCloseFrame& frame) {
 678   DCHECK(connected_);
 679   if (debug_visitor_) {
 680     debug_visitor_->OnConnectionCloseFrame(frame);
 681   }
 682   DVLOG(1) << ENDPOINT << "Connection " << connection_id()
 683            << " closed with error "
 684            << QuicUtils::ErrorToString(frame.error_code)
 685            << " " << frame.error_details;
 686   last_close_frames_.push_back(frame);
 687   return connected_;
 688 }
 689
 690 bool QuicConnection::OnGoAwayFrame(const QuicGoAwayFrame& frame) {
 691   DCHECK(connected_);
 692   DVLOG(1) << ENDPOINT << "Go away received with error "
 693            << QuicUtils::ErrorToString(frame.error_code)
 694            << " and reason:" << frame.reason_phrase;
 695   last_goaway_frames_.push_back(frame);
 696   return connected_;
 697 }
 698
 699 bool QuicConnection::OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) {
 700   DCHECK(connected_);
 701   DVLOG(1) << ENDPOINT << "WindowUpdate received for stream: "
 702            << frame.stream_id << " with byte offset: " << frame.byte_offset;
 703   last_window_update_frames_.push_back(frame);
 704   return connected_;
 705 }
 706
 707 bool QuicConnection::OnBlockedFrame(const QuicBlockedFrame& frame) {
 708   DCHECK(connected_);
 709   DVLOG(1) << ENDPOINT << "Blocked frame received for stream: "
 710            << frame.stream_id;
 711   last_blocked_frames_.push_back(frame);
 712   return connected_;
 713 }
 714
 715 void QuicConnection::OnPacketComplete() {
 716   // Don't do anything if this packet closed the connection.
 717   if (!connected_) {
 718     ClearLastFrames();
 719     return;
 720   }
 721
 722   DVLOG(1) << ENDPOINT << (last_packet_revived_ ? "Revived" : "Got")
 723            << " packet " << last_header_.packet_sequence_number
 724            << " with " << last_ack_frames_.size() << " acks, "
 725            << last_congestion_frames_.size() << " congestions, "
 726            << last_stop_waiting_frames_.size() << " stop_waiting, "
 727            << last_goaway_frames_.size() << " goaways, "
 728            << last_window_update_frames_.size() << " window updates, "
 729            << last_blocked_frames_.size() << " blocked, "
 730            << last_rst_frames_.size() << " rsts, "
 731            << last_close_frames_.size() << " closes, "
 732            << last_stream_frames_.size()
 733            << " stream frames for "
 734            << last_header_.public_header.connection_id;
 735
 736   MaybeQueueAck();
 737
 738   // Discard the packet if the visitor fails to process the stream frames.
 739   if (!last_stream_frames_.empty() &&
 740       !visitor_->OnStreamFrames(last_stream_frames_)) {
 741     return;
 742   }
 743
 744   if (last_packet_revived_) {
 745     received_packet_manager_.RecordPacketRevived(
 746         last_header_.packet_sequence_number);
 747   } else {
 748     received_packet_manager_.RecordPacketReceived(
 749         last_size_, last_header_, time_of_last_received_packet_);
 750   }
 751   for (size_t i = 0; i < last_stream_frames_.size(); ++i) {
 752     stats_.stream_bytes_received +=
 753         last_stream_frames_[i].data.TotalBufferSize();
 754   }
 755
 756   // Process window updates, blocked, stream resets, acks, then congestion
 757   // feedback.
 758   if (!last_window_update_frames_.empty()) {
 759     visitor_->OnWindowUpdateFrames(last_window_update_frames_);
 760   }
 761   if (!last_blocked_frames_.empty()) {
 762     visitor_->OnBlockedFrames(last_blocked_frames_);
 763   }
 764   for (size_t i = 0; i < last_goaway_frames_.size(); ++i) {
 765     visitor_->OnGoAway(last_goaway_frames_[i]);
 766   }
 767   for (size_t i = 0; i < last_rst_frames_.size(); ++i) {
 768     visitor_->OnRstStream(last_rst_frames_[i]);
 769   }
 770   for (size_t i = 0; i < last_ack_frames_.size(); ++i) {
 771     ProcessAckFrame(last_ack_frames_[i]);
 772   }
 773   for (size_t i = 0; i < last_congestion_frames_.size(); ++i) {
 774     sent_packet_manager_.OnIncomingQuicCongestionFeedbackFrame(
 775         last_congestion_frames_[i], time_of_last_received_packet_);
 776   }
 777   for (size_t i = 0; i < last_stop_waiting_frames_.size(); ++i) {
 778     ProcessStopWaitingFrame(last_stop_waiting_frames_[i]);
 779   }
 780   if (!last_close_frames_.empty()) {
 781     CloseConnection(last_close_frames_[0].error_code, true);
 782     DCHECK(!connected_);
 783   }
 784
 785   // If there are new missing packets to report, send an ack immediately.
 786   if (received_packet_manager_.HasNewMissingPackets()) {
 787     ack_queued_ = true;
 788     ack_alarm_->Cancel();
 789   }
 790
 791   UpdateStopWaitingCount();
 792
 793   ClearLastFrames();
 794 }
 795
 796 void QuicConnection::MaybeQueueAck() {
 797   // If the incoming packet was missing, send an ack immediately.
 798   ack_queued_ = received_packet_manager_.IsMissing(
 799       last_header_.packet_sequence_number);
 800
 801   if (!ack_queued_ && ShouldLastPacketInstigateAck()) {
 802     if (ack_alarm_->IsSet()) {
 803       ack_queued_ = true;
 804     } else {
 805       ack_alarm_->Set(clock_->ApproximateNow().Add(
 806           sent_packet_manager_.DelayedAckTime()));
 807       DVLOG(1) << "Ack timer set; next packet or timer will trigger ACK.";
 808     }
 809   }
 810
 811   if (ack_queued_) {
 812     ack_alarm_->Cancel();
 813   }
 814 }
 815
 816 void QuicConnection::ClearLastFrames() {
 817   last_stream_frames_.clear();
 818   last_goaway_frames_.clear();
 819   last_window_update_frames_.clear();
 820   last_blocked_frames_.clear();
 821   last_rst_frames_.clear();
 822   last_ack_frames_.clear();
 823   last_stop_waiting_frames_.clear();
 824   last_congestion_frames_.clear();
 825 }
 826
 827 QuicAckFrame* QuicConnection::CreateAckFrame() {
 828   QuicAckFrame* outgoing_ack = new QuicAckFrame();
 829   received_packet_manager_.UpdateReceivedPacketInfo(
 830       &(outgoing_ack->received_info), clock_->ApproximateNow());
 831   UpdateStopWaiting(&(outgoing_ack->sent_info));
 832   DVLOG(1) << ENDPOINT << "Creating ack frame: " << *outgoing_ack;
 833   return outgoing_ack;
 834 }
 835
 836 QuicCongestionFeedbackFrame* QuicConnection::CreateFeedbackFrame() {
 837   return new QuicCongestionFeedbackFrame(outgoing_congestion_feedback_);
 838 }
 839
 840 QuicStopWaitingFrame* QuicConnection::CreateStopWaitingFrame() {
 841   QuicStopWaitingFrame stop_waiting;
 842   UpdateStopWaiting(&stop_waiting);
 843   return new QuicStopWaitingFrame(stop_waiting);
 844 }
 845
 846 bool QuicConnection::ShouldLastPacketInstigateAck() const {
 847   if (!last_stream_frames_.empty() ||
 848       !last_goaway_frames_.empty() ||
 849       !last_rst_frames_.empty() ||
 850       !last_window_update_frames_.empty() ||
 851       !last_blocked_frames_.empty()) {
 852     return true;
 853   }
 854
 855   if (!last_ack_frames_.empty() &&
 856       last_ack_frames_.back().received_info.is_truncated) {
 857     return true;
 858   }
 859   return false;
 860 }
 861
 862 void QuicConnection::UpdateStopWaitingCount() {
 863   if (last_ack_frames_.empty()) {
 864     return;
 865   }
 866
 867   // If the peer is still waiting for a packet that we are no longer planning to
 868   // send, send an ack to raise the high water mark.
 869   if (!last_ack_frames_.back().received_info.missing_packets.empty() &&
 870       GetLeastUnacked() >
 871           *last_ack_frames_.back().received_info.missing_packets.begin()) {
 872     ++stop_waiting_count_;
 873   } else {
 874     stop_waiting_count_ = 0;
 875   }
 876 }
 877
 878 QuicPacketSequenceNumber QuicConnection::GetLeastUnacked() const {
 879   return sent_packet_manager_.HasUnackedPackets() ?
 880       sent_packet_manager_.GetLeastUnackedSentPacket() :
 881       packet_creator_.sequence_number() + 1;
 882 }
 883
 884 void QuicConnection::MaybeSendInResponseToPacket() {
 885   if (!connected_) {
 886     return;
 887   }
 888   ScopedPacketBundler bundler(this, ack_queued_ ? SEND_ACK : NO_ACK);
 889
 890   // Now that we have received an ack, we might be able to send packets which
 891   // are queued locally, or drain streams which are blocked.
 892   QuicTime::Delta delay = sent_packet_manager_.TimeUntilSend(
 893       time_of_last_received_packet_, NOT_RETRANSMISSION,
 894       HAS_RETRANSMITTABLE_DATA, NOT_HANDSHAKE);
 895   if (delay.IsZero()) {
 896     send_alarm_->Cancel();
 897     WriteIfNotBlocked();
 898   } else if (!delay.IsInfinite()) {
 899     send_alarm_->Cancel();
 900     send_alarm_->Set(time_of_last_received_packet_.Add(delay));
 901   }
 902 }
 903
 904 void QuicConnection::SendVersionNegotiationPacket() {
 905   // TODO(alyssar): implement zero server state negotiation.
 906   pending_version_negotiation_packet_ = true;
 907   if (writer_->IsWriteBlocked()) {
 908     visitor_->OnWriteBlocked();
 909     return;
 910   }
 911   scoped_ptr<QuicEncryptedPacket> version_packet(
 912       packet_creator_.SerializeVersionNegotiationPacket(
 913           framer_.supported_versions()));
 914   WriteResult result = writer_->WritePacket(
 915       version_packet->data(), version_packet->length(),
 916       self_address().address(), peer_address());
 917
 918   if (result.status == WRITE_STATUS_ERROR) {
 919     // We can't send an error as the socket is presumably borked.
 920     CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
 921     return;
 922   }
 923   if (result.status == WRITE_STATUS_BLOCKED) {
 924     visitor_->OnWriteBlocked();
 925     if (writer_->IsWriteBlockedDataBuffered()) {
 926       pending_version_negotiation_packet_ = false;
 927     }
 928     return;
 929   }
 930
 931   pending_version_negotiation_packet_ = false;
 932 }
 933
 934 QuicConsumedData QuicConnection::SendStreamData(
 935     QuicStreamId id,
 936     const IOVector& data,
 937     QuicStreamOffset offset,
 938     bool fin,
 939     QuicAckNotifier::DelegateInterface* delegate) {
 940   if (!fin && data.Empty()) {
 941     LOG(DFATAL) << "Attempt to send empty stream frame";
 942   }
 943
 944   // This notifier will be owned by the AckNotifierManager (or deleted below if
 945   // no data or FIN was consumed).
 946   QuicAckNotifier* notifier = NULL;
 947   if (delegate) {
 948     notifier = new QuicAckNotifier(delegate);
 949   }
 950
 951   // Opportunistically bundle an ack with every outgoing packet, unless it's the
 952   // crypto stream.
 953   ScopedPacketBundler ack_bundler(
 954       this, id != kCryptoStreamId ? BUNDLE_PENDING_ACK : NO_ACK);
 955   QuicConsumedData consumed_data =
 956       packet_generator_.ConsumeData(id, data, offset, fin, notifier);
 957
 958   if (notifier &&
 959       (consumed_data.bytes_consumed == 0 && !consumed_data.fin_consumed)) {
 960     // No data was consumed, nor was a fin consumed, so delete the notifier.
 961     delete notifier;
 962   }
 963
 964   return consumed_data;
 965 }
 966
 967 void QuicConnection::SendRstStream(QuicStreamId id,
 968                                    QuicRstStreamErrorCode error,
 969                                    QuicStreamOffset bytes_written) {
 970   // Opportunistically bundle an ack with this outgoing packet.
 971   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
 972   packet_generator_.AddControlFrame(
 973       QuicFrame(new QuicRstStreamFrame(id, error, bytes_written)));
 974 }
 975
 976 void QuicConnection::SendWindowUpdate(QuicStreamId id,
 977                                       QuicStreamOffset byte_offset) {
 978   // Opportunistically bundle an ack with this outgoing packet.
 979   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
 980   packet_generator_.AddControlFrame(
 981       QuicFrame(new QuicWindowUpdateFrame(id, byte_offset)));
 982 }
 983
 984 void QuicConnection::SendBlocked(QuicStreamId id) {
 985   // Opportunistically bundle an ack with this outgoing packet.
 986   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
 987   packet_generator_.AddControlFrame(QuicFrame(new QuicBlockedFrame(id)));
 988 }
 989
 990 const QuicConnectionStats& QuicConnection::GetStats() {
 991   // Update rtt and estimated bandwidth.
 992   stats_.rtt = sent_packet_manager_.SmoothedRtt().ToMicroseconds();
 993   stats_.estimated_bandwidth =
 994       sent_packet_manager_.BandwidthEstimate().ToBytesPerSecond();
 995   return stats_;
 996 }
 997
 998 void QuicConnection::ProcessUdpPacket(const IPEndPoint& self_address,
 999                                       const IPEndPoint& peer_address,
1000                                       const QuicEncryptedPacket& packet) {
1001   if (!connected_) {
1002     return;
1003   }
1004   if (debug_visitor_) {
1005     debug_visitor_->OnPacketReceived(self_address, peer_address, packet);
1006   }
1007   last_packet_revived_ = false;
1008   last_size_ = packet.length();
1009
1010   address_migrating_ = false;
1011
1012   if (peer_address_.address().empty()) {
1013     peer_address_ = peer_address;
1014   }
1015   if (self_address_.address().empty()) {
1016     self_address_ = self_address;
1017   }
1018
1019   if (!(peer_address == peer_address_ && self_address == self_address_)) {
1020     address_migrating_ = true;
1021   }
1022
1023   stats_.bytes_received += packet.length();
1024   ++stats_.packets_received;
1025
1026   if (!framer_.ProcessPacket(packet)) {
1027     // If we are unable to decrypt this packet, it might be
1028     // because the CHLO or SHLO packet was lost.
1029     if (encryption_level_ != ENCRYPTION_FORWARD_SECURE &&
1030         framer_.error() == QUIC_DECRYPTION_FAILURE &&
1031         undecryptable_packets_.size() < kMaxUndecryptablePackets) {
1032       QueueUndecryptablePacket(packet);
1033     }
1034     DVLOG(1) << ENDPOINT << "Unable to process packet.  Last packet processed: "
1035              << last_header_.packet_sequence_number;
1036     return;
1037   }
1038
1039   MaybeProcessUndecryptablePackets();
1040   MaybeProcessRevivedPacket();
1041   MaybeSendInResponseToPacket();
1042 }
1043
1044 void QuicConnection::OnCanWrite() {
1045   DCHECK(!writer_->IsWriteBlocked());
1046
1047   WriteQueuedPackets();
1048   WritePendingRetransmissions();
1049
1050   IsHandshake pending_handshake = visitor_->HasPendingHandshake() ?
1051       IS_HANDSHAKE : NOT_HANDSHAKE;
1052   // Sending queued packets may have caused the socket to become write blocked,
1053   // or the congestion manager to prohibit sending.  If we've sent everything
1054   // we had queued and we're still not blocked, let the visitor know it can
1055   // write more.
1056   if (!CanWrite(NOT_RETRANSMISSION, HAS_RETRANSMITTABLE_DATA,
1057                 pending_handshake)) {
1058     return;
1059   }
1060
1061   {  // Limit the scope of the bundler.
1062     // Set |include_ack| to false in bundler; ack inclusion happens elsewhere.
1063     ScopedPacketBundler bundler(this, NO_ACK);
1064     visitor_->OnCanWrite();
1065   }
1066
1067   // After the visitor writes, it may have caused the socket to become write
1068   // blocked or the congestion manager to prohibit sending, so check again.
1069   pending_handshake = visitor_->HasPendingHandshake() ?
1070       IS_HANDSHAKE : NOT_HANDSHAKE;
1071   if (visitor_->HasPendingWrites() && !resume_writes_alarm_->IsSet() &&
1072       CanWrite(NOT_RETRANSMISSION, HAS_RETRANSMITTABLE_DATA,
1073                pending_handshake)) {
1074     // We're not write blocked, but some stream didn't write out all of its
1075     // bytes. Register for 'immediate' resumption so we'll keep writing after
1076     // other connections and events have had a chance to use the thread.
1077     resume_writes_alarm_->Set(clock_->ApproximateNow());
1078   }
1079 }
1080
1081 void QuicConnection::WriteIfNotBlocked() {
1082   if (!writer_->IsWriteBlocked()) {
1083     OnCanWrite();
1084   }
1085 }
1086
1087 bool QuicConnection::ProcessValidatedPacket() {
1088   if (address_migrating_) {
1089     SendConnectionCloseWithDetails(
1090         QUIC_ERROR_MIGRATING_ADDRESS,
1091         "Address migration is not yet a supported feature");
1092     return false;
1093   }
1094   time_of_last_received_packet_ = clock_->Now();
1095   DVLOG(1) << ENDPOINT << "time of last received packet: "
1096            << time_of_last_received_packet_.ToDebuggingValue();
1097
1098   if (is_server_ && encryption_level_ == ENCRYPTION_NONE &&
1099       last_size_ > options()->max_packet_length) {
1100     options()->max_packet_length = last_size_;
1101   }
1102   return true;
1103 }
1104
1105 void QuicConnection::WriteQueuedPackets() {
1106   DCHECK(!writer_->IsWriteBlocked());
1107
1108   if (pending_version_negotiation_packet_) {
1109     SendVersionNegotiationPacket();
1110   }
1111
1112   QueuedPacketList::iterator packet_iterator = queued_packets_.begin();
1113   while (!writer_->IsWriteBlocked() &&
1114          packet_iterator != queued_packets_.end()) {
1115     if (WritePacket(*packet_iterator)) {
1116       delete packet_iterator->packet;
1117       packet_iterator = queued_packets_.erase(packet_iterator);
1118     } else {
1119       // Continue, because some queued packets may still be writable.
1120       // This can happen if a retransmit send fails.
1121       ++packet_iterator;
1122     }
1123   }
1124 }
1125
1126 void QuicConnection::WritePendingRetransmissions() {
1127   // Keep writing as long as there's a pending retransmission which can be
1128   // written.
1129   while (sent_packet_manager_.HasPendingRetransmissions()) {
1130     const QuicSentPacketManager::PendingRetransmission pending =
1131         sent_packet_manager_.NextPendingRetransmission();
1132     if (GetPacketType(&pending.retransmittable_frames) == NORMAL &&
1133         !CanWrite(pending.transmission_type, HAS_RETRANSMITTABLE_DATA,
1134                   pending.retransmittable_frames.HasCryptoHandshake())) {
1135       break;
1136     }
1137
1138     // Re-packetize the frames with a new sequence number for retransmission.
1139     // Retransmitted data packets do not use FEC, even when it's enabled.
1140     // Retransmitted packets use the same sequence number length as the
1141     // original.
1142     // Flush the packet creator before making a new packet.
1143     // TODO(ianswett): Implement ReserializeAllFrames as a separate path that
1144     // does not require the creator to be flushed.
1145     Flush();
1146     SerializedPacket serialized_packet = packet_creator_.ReserializeAllFrames(
1147         pending.retransmittable_frames.frames(),
1148         pending.sequence_number_length);
1149
1150     DVLOG(1) << ENDPOINT << "Retransmitting " << pending.sequence_number
1151              << " as " << serialized_packet.sequence_number;
1152     if (debug_visitor_) {
1153       debug_visitor_->OnPacketRetransmitted(
1154           pending.sequence_number, serialized_packet.sequence_number);
1155     }
1156     sent_packet_manager_.OnRetransmittedPacket(
1157         pending.sequence_number, serialized_packet.sequence_number);
1158
1159     SendOrQueuePacket(pending.retransmittable_frames.encryption_level(),
1160                       serialized_packet,
1161                       pending.transmission_type);
1162   }
1163 }
1164
1165 void QuicConnection::RetransmitUnackedPackets(
1166     RetransmissionType retransmission_type) {
1167   sent_packet_manager_.RetransmitUnackedPackets(retransmission_type);
1168
1169   WriteIfNotBlocked();
1170 }
1171
1172 bool QuicConnection::ShouldGeneratePacket(
1173     TransmissionType transmission_type,
1174     HasRetransmittableData retransmittable,
1175     IsHandshake handshake) {
1176   // We should serialize handshake packets immediately to ensure that they
1177   // end up sent at the right encryption level.
1178   if (handshake == IS_HANDSHAKE) {
1179     return true;
1180   }
1181
1182   return CanWrite(transmission_type, retransmittable, handshake);
1183 }
1184
1185 bool QuicConnection::CanWrite(TransmissionType transmission_type,
1186                               HasRetransmittableData retransmittable,
1187                               IsHandshake handshake) {
1188   if (writer_->IsWriteBlocked()) {
1189     visitor_->OnWriteBlocked();
1190     return false;
1191   }
1192
1193   // TODO(rch): consider removing this check so that if an ACK comes in
1194   // before the alarm goes it, we might be able send out a packet.
1195   // This check assumes that if the send alarm is set, it applies equally to all
1196   // types of transmissions.
1197   if (send_alarm_->IsSet()) {
1198     DVLOG(1) << "Send alarm set.  Not sending.";
1199     return false;
1200   }
1201
1202   QuicTime now = clock_->Now();
1203   QuicTime::Delta delay = sent_packet_manager_.TimeUntilSend(
1204       now, transmission_type, retransmittable, handshake);
1205   if (delay.IsInfinite()) {
1206     return false;
1207   }
1208
1209   // If the scheduler requires a delay, then we can not send this packet now.
1210   if (!delay.IsZero()) {
1211     send_alarm_->Cancel();
1212     send_alarm_->Set(now.Add(delay));
1213     DVLOG(1) << "Delaying sending.";
1214     return false;
1215   }
1216   return true;
1217 }
1218
1219 bool QuicConnection::WritePacket(QueuedPacket packet) {
1220   QuicPacketSequenceNumber sequence_number = packet.sequence_number;
1221   if (ShouldDiscardPacket(packet.encryption_level,
1222                           sequence_number,
1223                           packet.retransmittable)) {
1224     return true;
1225   }
1226
1227   // If the packet is CONNECTION_CLOSE, we need to try to send it immediately
1228   // and encrypt it to hand it off to TimeWaitListManager.
1229   // If the packet is QUEUED, we don't re-consult the congestion control.
1230   // This ensures packets are sent in sequence number order.
1231   // TODO(ianswett): The congestion control should have been consulted before
1232   // serializing the packet, so this could be turned into a LOG_IF(DFATAL).
1233   if (packet.type == NORMAL && !CanWrite(packet.transmission_type,
1234                                          packet.retransmittable,
1235                                          packet.handshake)) {
1236     return false;
1237   }
1238
1239   // Some encryption algorithms require the packet sequence numbers not be
1240   // repeated.
1241   DCHECK_LE(sequence_number_of_last_sent_packet_, sequence_number);
1242   sequence_number_of_last_sent_packet_ = sequence_number;
1243
1244   QuicEncryptedPacket* encrypted = framer_.EncryptPacket(
1245       packet.encryption_level, sequence_number, *packet.packet);
1246   if (encrypted == NULL) {
1247     LOG(DFATAL) << ENDPOINT << "Failed to encrypt packet number "
1248                 << sequence_number;
1249     // CloseConnection does not send close packet, so no infinite loop here.
1250     CloseConnection(QUIC_ENCRYPTION_FAILURE, false);
1251     return false;
1252   }
1253
1254   // Connection close packets are eventually owned by TimeWaitListManager.
1255   // Others are deleted at the end of this call.
1256   scoped_ptr<QuicEncryptedPacket> encrypted_deleter;
1257   if (packet.type == CONNECTION_CLOSE) {
1258     DCHECK(connection_close_packet_.get() == NULL);
1259     connection_close_packet_.reset(encrypted);
1260     // This assures we won't try to write *forced* packets when blocked.
1261     // Return true to stop processing.
1262     if (writer_->IsWriteBlocked()) {
1263       visitor_->OnWriteBlocked();
1264       return true;
1265     }
1266   } else {
1267     encrypted_deleter.reset(encrypted);
1268   }
1269
1270   LOG_IF(DFATAL, encrypted->length() > options()->max_packet_length)
1271       << "Writing an encrypted packet larger than max_packet_length:"
1272       << options()->max_packet_length << " encrypted length: "
1273       << encrypted->length();
1274   DVLOG(1) << ENDPOINT << "Sending packet " << sequence_number
1275            << " : " << (packet.packet->is_fec_packet() ? "FEC " :
1276                (packet.retransmittable == HAS_RETRANSMITTABLE_DATA
1277                     ? "data bearing " : " ack only "))
1278            << ", encryption level: "
1279            << QuicUtils::EncryptionLevelToString(packet.encryption_level)
1280            << ", length:" << packet.packet->length() << ", encrypted length:"
1281            << encrypted->length();
1282   DVLOG(2) << ENDPOINT << "packet(" << sequence_number << "): " << std::endl
1283            << QuicUtils::StringToHexASCIIDump(packet.packet->AsStringPiece());
1284
1285   DCHECK(encrypted->length() <= kMaxPacketSize ||
1286          FLAGS_quic_allow_oversized_packets_for_test)
1287       << "Packet " << sequence_number << " will not be read; too large: "
1288       << packet.packet->length() << " " << encrypted->length() << " "
1289       << " close: " << (packet.type == CONNECTION_CLOSE ? "yes" : "no");
1290
1291   DCHECK(pending_write_.get() == NULL);
1292   pending_write_.reset(new QueuedPacket(packet));
1293
1294   WriteResult result = writer_->WritePacket(encrypted->data(),
1295                                             encrypted->length(),
1296                                             self_address().address(),
1297                                             peer_address());
1298   if (result.error_code == ERR_IO_PENDING) {
1299     DCHECK_EQ(WRITE_STATUS_BLOCKED, result.status);
1300   }
1301   if (debug_visitor_) {
1302     // Pass the write result to the visitor.
1303     debug_visitor_->OnPacketSent(sequence_number,
1304                                  packet.encryption_level,
1305                                  packet.transmission_type,
1306                                  *encrypted,
1307                                  result);
1308   }
1309   if (result.status == WRITE_STATUS_BLOCKED) {
1310     visitor_->OnWriteBlocked();
1311     // If the socket buffers the the data, then the packet should not
1312     // be queued and sent again, which would result in an unnecessary
1313     // duplicate packet being sent.  The helper must call OnPacketSent
1314     // when the packet is actually sent.
1315     if (writer_->IsWriteBlockedDataBuffered()) {
1316       return true;
1317     }
1318     pending_write_.reset();
1319     return false;
1320   }
1321
1322   if (OnPacketSent(result)) {
1323     return true;
1324   }
1325   return false;
1326 }
1327
1328 bool QuicConnection::ShouldDiscardPacket(
1329     EncryptionLevel level,
1330     QuicPacketSequenceNumber sequence_number,
1331     HasRetransmittableData retransmittable) {
1332   if (!connected_) {
1333     DVLOG(1) << ENDPOINT
1334              << "Not sending packet as connection is disconnected.";
1335     return true;
1336   }
1337
1338   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE &&
1339       level == ENCRYPTION_NONE) {
1340     // Drop packets that are NULL encrypted since the peer won't accept them
1341     // anymore.
1342     DVLOG(1) << ENDPOINT << "Dropping packet: " << sequence_number
1343              << " since the packet is NULL encrypted.";
1344     sent_packet_manager_.DiscardUnackedPacket(sequence_number);
1345     return true;
1346   }
1347
1348   // If the packet has been discarded before sending, don't send it.
1349   // This occurs if a packet gets serialized, queued, then discarded.
1350   if (!sent_packet_manager_.IsUnacked(sequence_number)) {
1351     DVLOG(1) << ENDPOINT << "Dropping packet before sending: "
1352              << sequence_number << " since it has already been discarded.";
1353     return true;
1354   }
1355
1356   if (retransmittable == HAS_RETRANSMITTABLE_DATA &&
1357       !sent_packet_manager_.HasRetransmittableFrames(sequence_number)) {
1358     DVLOG(1) << ENDPOINT << "Dropping packet: " << sequence_number
1359              << " since a previous transmission has been acked.";
1360     sent_packet_manager_.DiscardUnackedPacket(sequence_number);
1361     return true;
1362   }
1363
1364   return false;
1365 }
1366
1367 bool QuicConnection::OnPacketSent(WriteResult result) {
1368   DCHECK_NE(WRITE_STATUS_BLOCKED, result.status);
1369   if (pending_write_.get() == NULL) {
1370     LOG(DFATAL) << "OnPacketSent called without a pending write.";
1371     return false;
1372   }
1373
1374   QuicPacketSequenceNumber sequence_number = pending_write_->sequence_number;
1375   TransmissionType transmission_type  = pending_write_->transmission_type;
1376   HasRetransmittableData retransmittable = pending_write_->retransmittable;
1377   size_t length = pending_write_->length;
1378   pending_write_.reset();
1379
1380   if (result.status == WRITE_STATUS_ERROR) {
1381     DVLOG(1) << "Write failed with error code: " << result.error_code;
1382     // We can't send an error as the socket is presumably borked.
1383     CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
1384     return false;
1385   }
1386
1387   QuicTime now = clock_->Now();
1388   if (transmission_type == NOT_RETRANSMISSION) {
1389     time_of_last_sent_new_packet_ = now;
1390   }
1391   DVLOG(1) << ENDPOINT << "time of last sent packet: "
1392            << now.ToDebuggingValue();
1393
1394   // TODO(ianswett): Change the sequence number length and other packet creator
1395   // options by a more explicit API than setting a struct value directly.
1396   packet_creator_.UpdateSequenceNumberLength(
1397       received_packet_manager_.least_packet_awaited_by_peer(),
1398       sent_packet_manager_.BandwidthEstimate().ToBytesPerPeriod(
1399           sent_packet_manager_.SmoothedRtt()));
1400
1401   bool reset_retransmission_alarm =
1402       sent_packet_manager_.OnPacketSent(sequence_number, now, length,
1403                                         transmission_type, retransmittable);
1404
1405   if (reset_retransmission_alarm || !retransmission_alarm_->IsSet()) {
1406     retransmission_alarm_->Cancel();
1407     QuicTime retransmission_time = sent_packet_manager_.GetRetransmissionTime();
1408     if (retransmission_time != QuicTime::Zero()) {
1409       retransmission_alarm_->Set(retransmission_time);
1410     }
1411   }
1412
1413   stats_.bytes_sent += result.bytes_written;
1414   ++stats_.packets_sent;
1415
1416   if (transmission_type != NOT_RETRANSMISSION) {
1417     stats_.bytes_retransmitted += result.bytes_written;
1418     ++stats_.packets_retransmitted;
1419   }
1420
1421   return true;
1422 }
1423
1424 bool QuicConnection::OnSerializedPacket(
1425     const SerializedPacket& serialized_packet) {
1426   if (serialized_packet.retransmittable_frames) {
1427     serialized_packet.retransmittable_frames->
1428         set_encryption_level(encryption_level_);
1429   }
1430   sent_packet_manager_.OnSerializedPacket(serialized_packet);
1431   // The TransmissionType is NOT_RETRANSMISSION because all retransmissions
1432   // serialize packets and invoke SendOrQueuePacket directly.
1433   return SendOrQueuePacket(encryption_level_,
1434                            serialized_packet,
1435                            NOT_RETRANSMISSION);
1436 }
1437
1438 bool QuicConnection::SendOrQueuePacket(EncryptionLevel level,
1439                                        const SerializedPacket& packet,
1440                                        TransmissionType transmission_type) {
1441   if (packet.packet == NULL) {
1442     LOG(DFATAL) << "NULL packet passed in to SendOrQueuePacket";
1443     return true;
1444   }
1445
1446   sent_entropy_manager_.RecordPacketEntropyHash(packet.sequence_number,
1447                                                 packet.entropy_hash);
1448   QueuedPacket queued_packet(packet, level, transmission_type);
1449   // If there are already queued packets, put this at the end,
1450   // unless it's ConnectionClose, in which case it is written immediately.
1451   if ((queued_packet.type == CONNECTION_CLOSE || queued_packets_.empty()) &&
1452       WritePacket(queued_packet)) {
1453     delete packet.packet;
1454     return true;
1455   }
1456   queued_packet.type = QUEUED;
1457   queued_packets_.push_back(queued_packet);
1458   return false;
1459 }
1460
1461 void QuicConnection::UpdateStopWaiting(QuicStopWaitingFrame* stop_waiting) {
1462   stop_waiting->least_unacked = GetLeastUnacked();
1463   stop_waiting->entropy_hash = sent_entropy_manager_.EntropyHash(
1464       stop_waiting->least_unacked - 1);
1465 }
1466
1467 void QuicConnection::SendAck() {
1468   ack_alarm_->Cancel();
1469   stop_waiting_count_ = 0;
1470   // TODO(rch): delay this until the CreateFeedbackFrame
1471   // method is invoked.  This requires changes SetShouldSendAck
1472   // to be a no-arg method, and re-jiggering its implementation.
1473   bool send_feedback = false;
1474   if (received_packet_manager_.GenerateCongestionFeedback(
1475           &outgoing_congestion_feedback_)) {
1476     DVLOG(1) << ENDPOINT << "Sending feedback: "
1477              << outgoing_congestion_feedback_;
1478     send_feedback = true;
1479   }
1480
1481   packet_generator_.SetShouldSendAck(send_feedback,
1482                                      version() > QUIC_VERSION_15);
1483 }
1484
1485 void QuicConnection::OnRetransmissionTimeout() {
1486   if (!sent_packet_manager_.HasUnackedPackets()) {
1487     return;
1488   }
1489
1490   sent_packet_manager_.OnRetransmissionTimeout();
1491
1492   WriteIfNotBlocked();
1493
1494   // Ensure the retransmission alarm is always set if there are unacked packets.
1495   if (!HasQueuedData() && !retransmission_alarm_->IsSet()) {
1496     QuicTime rto_timeout = sent_packet_manager_.GetRetransmissionTime();
1497     if (rto_timeout != QuicTime::Zero()) {
1498       retransmission_alarm_->Set(rto_timeout);
1499     }
1500   }
1501 }
1502
1503 void QuicConnection::SetEncrypter(EncryptionLevel level,
1504                                   QuicEncrypter* encrypter) {
1505   framer_.SetEncrypter(level, encrypter);
1506 }
1507
1508 const QuicEncrypter* QuicConnection::encrypter(EncryptionLevel level) const {
1509   return framer_.encrypter(level);
1510 }
1511
1512 void QuicConnection::SetDefaultEncryptionLevel(EncryptionLevel level) {
1513   encryption_level_ = level;
1514 }
1515
1516 void QuicConnection::SetDecrypter(QuicDecrypter* decrypter) {
1517   framer_.SetDecrypter(decrypter);
1518 }
1519
1520 void QuicConnection::SetAlternativeDecrypter(QuicDecrypter* decrypter,
1521                                              bool latch_once_used) {
1522   framer_.SetAlternativeDecrypter(decrypter, latch_once_used);
1523 }
1524
1525 const QuicDecrypter* QuicConnection::decrypter() const {
1526   return framer_.decrypter();
1527 }
1528
1529 const QuicDecrypter* QuicConnection::alternative_decrypter() const {
1530   return framer_.alternative_decrypter();
1531 }
1532
1533 void QuicConnection::QueueUndecryptablePacket(
1534     const QuicEncryptedPacket& packet) {
1535   DVLOG(1) << ENDPOINT << "Queueing undecryptable packet.";
1536   undecryptable_packets_.push_back(packet.Clone());
1537 }
1538
1539 void QuicConnection::MaybeProcessUndecryptablePackets() {
1540   if (undecryptable_packets_.empty() || encryption_level_ == ENCRYPTION_NONE) {
1541     return;
1542   }
1543
1544   while (connected_ && !undecryptable_packets_.empty()) {
1545     DVLOG(1) << ENDPOINT << "Attempting to process undecryptable packet";
1546     QuicEncryptedPacket* packet = undecryptable_packets_.front();
1547     if (!framer_.ProcessPacket(*packet) &&
1548         framer_.error() == QUIC_DECRYPTION_FAILURE) {
1549       DVLOG(1) << ENDPOINT << "Unable to process undecryptable packet...";
1550       break;
1551     }
1552     DVLOG(1) << ENDPOINT << "Processed undecryptable packet!";
1553     delete packet;
1554     undecryptable_packets_.pop_front();
1555   }
1556
1557   // Once forward secure encryption is in use, there will be no
1558   // new keys installed and hence any undecryptable packets will
1559   // never be able to be decrypted.
1560   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE) {
1561     STLDeleteElements(&undecryptable_packets_);
1562   }
1563 }
1564
1565 void QuicConnection::MaybeProcessRevivedPacket() {
1566   QuicFecGroup* group = GetFecGroup();
1567   if (!connected_ || group == NULL || !group->CanRevive()) {
1568     return;
1569   }
1570   QuicPacketHeader revived_header;
1571   char revived_payload[kMaxPacketSize];
1572   size_t len = group->Revive(&revived_header, revived_payload, kMaxPacketSize);
1573   revived_header.public_header.connection_id = connection_id_;
1574   revived_header.public_header.version_flag = false;
1575   revived_header.public_header.reset_flag = false;
1576   revived_header.fec_flag = false;
1577   revived_header.is_in_fec_group = NOT_IN_FEC_GROUP;
1578   revived_header.fec_group = 0;
1579   group_map_.erase(last_header_.fec_group);
1580   delete group;
1581
1582   last_packet_revived_ = true;
1583   if (debug_visitor_) {
1584     debug_visitor_->OnRevivedPacket(revived_header,
1585                                     StringPiece(revived_payload, len));
1586   }
1587
1588   ++stats_.packets_revived;
1589   framer_.ProcessRevivedPacket(&revived_header,
1590                                StringPiece(revived_payload, len));
1591 }
1592
1593 QuicFecGroup* QuicConnection::GetFecGroup() {
1594   QuicFecGroupNumber fec_group_num = last_header_.fec_group;
1595   if (fec_group_num == 0) {
1596     return NULL;
1597   }
1598   if (group_map_.count(fec_group_num) == 0) {
1599     if (group_map_.size() >= kMaxFecGroups) {  // Too many groups
1600       if (fec_group_num < group_map_.begin()->first) {
1601         // The group being requested is a group we've seen before and deleted.
1602         // Don't recreate it.
1603         return NULL;
1604       }
1605       // Clear the lowest group number.
1606       delete group_map_.begin()->second;
1607       group_map_.erase(group_map_.begin());
1608     }
1609     group_map_[fec_group_num] = new QuicFecGroup();
1610   }
1611   return group_map_[fec_group_num];
1612 }
1613
1614 void QuicConnection::SendConnectionClose(QuicErrorCode error) {
1615   SendConnectionCloseWithDetails(error, string());
1616 }
1617
1618 void QuicConnection::SendConnectionCloseWithDetails(QuicErrorCode error,
1619                                                     const string& details) {
1620   // If we're write blocked, WritePacket() will not send, but will capture the
1621   // serialized packet.
1622   SendConnectionClosePacket(error, details);
1623   if (connected_) {
1624     // It's possible that while sending the connection close packet, we get a
1625     // socket error and disconnect right then and there.  Avoid a double
1626     // disconnect in that case.
1627     CloseConnection(error, false);
1628   }
1629 }
1630
1631 void QuicConnection::SendConnectionClosePacket(QuicErrorCode error,
1632                                                const string& details) {
1633   DVLOG(1) << ENDPOINT << "Force closing " << connection_id()
1634            << " with error " << QuicUtils::ErrorToString(error)
1635            << " (" << error << ") " << details;
1636   ScopedPacketBundler ack_bundler(this, SEND_ACK);
1637   QuicConnectionCloseFrame* frame = new QuicConnectionCloseFrame();
1638   frame->error_code = error;
1639   frame->error_details = details;
1640   packet_generator_.AddControlFrame(QuicFrame(frame));
1641   Flush();
1642 }
1643
1644 void QuicConnection::CloseConnection(QuicErrorCode error, bool from_peer) {
1645   if (!connected_) {
1646     DLOG(DFATAL) << "Error: attempt to close an already closed connection"
1647                  << base::debug::StackTrace().ToString();
1648     return;
1649   }
1650   connected_ = false;
1651   visitor_->OnConnectionClosed(error, from_peer);
1652   // Cancel the alarms so they don't trigger any action now that the
1653   // connection is closed.
1654   ack_alarm_->Cancel();
1655   resume_writes_alarm_->Cancel();
1656   retransmission_alarm_->Cancel();
1657   send_alarm_->Cancel();
1658   timeout_alarm_->Cancel();
1659 }
1660
1661 void QuicConnection::SendGoAway(QuicErrorCode error,
1662                                 QuicStreamId last_good_stream_id,
1663                                 const string& reason) {
1664   DVLOG(1) << ENDPOINT << "Going away with error "
1665            << QuicUtils::ErrorToString(error)
1666            << " (" << error << ")";
1667
1668   // Opportunistically bundle an ack with this outgoing packet.
1669   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1670   packet_generator_.AddControlFrame(
1671       QuicFrame(new QuicGoAwayFrame(error, last_good_stream_id, reason)));
1672 }
1673
1674 void QuicConnection::CloseFecGroupsBefore(
1675     QuicPacketSequenceNumber sequence_number) {
1676   FecGroupMap::iterator it = group_map_.begin();
1677   while (it != group_map_.end()) {
1678     // If this is the current group or the group doesn't protect this packet
1679     // we can ignore it.
1680     if (last_header_.fec_group == it->first ||
1681         !it->second->ProtectsPacketsBefore(sequence_number)) {
1682       ++it;
1683       continue;
1684     }
1685     QuicFecGroup* fec_group = it->second;
1686     DCHECK(!fec_group->CanRevive());
1687     FecGroupMap::iterator next = it;
1688     ++next;
1689     group_map_.erase(it);
1690     delete fec_group;
1691     it = next;
1692   }
1693 }
1694
1695 void QuicConnection::Flush() {
1696   packet_generator_.FlushAllQueuedFrames();
1697 }
1698
1699 bool QuicConnection::HasQueuedData() const {
1700   return pending_version_negotiation_packet_ ||
1701       !queued_packets_.empty() || packet_generator_.HasQueuedFrames();
1702 }
1703
1704 bool QuicConnection::CanWriteStreamData() {
1705   // Don't write stream data if there are negotiation or queued data packets
1706   // to send. Otherwise, continue and bundle as many frames as possible.
1707   if (pending_version_negotiation_packet_ || !queued_packets_.empty()) {
1708     return false;
1709   }
1710
1711   IsHandshake pending_handshake = visitor_->HasPendingHandshake() ?
1712       IS_HANDSHAKE : NOT_HANDSHAKE;
1713   // Sending queued packets may have caused the socket to become write blocked,
1714   // or the congestion manager to prohibit sending.  If we've sent everything
1715   // we had queued and we're still not blocked, let the visitor know it can
1716   // write more.
1717   return ShouldGeneratePacket(NOT_RETRANSMISSION, HAS_RETRANSMITTABLE_DATA,
1718                               pending_handshake);
1719 }
1720
1721 void QuicConnection::SetIdleNetworkTimeout(QuicTime::Delta timeout) {
1722   if (timeout < idle_network_timeout_) {
1723     idle_network_timeout_ = timeout;
1724     CheckForTimeout();
1725   } else {
1726     idle_network_timeout_ = timeout;
1727   }
1728 }
1729
1730 void QuicConnection::SetOverallConnectionTimeout(QuicTime::Delta timeout) {
1731   if (timeout < overall_connection_timeout_) {
1732     overall_connection_timeout_ = timeout;
1733     CheckForTimeout();
1734   } else {
1735     overall_connection_timeout_ = timeout;
1736   }
1737 }
1738
1739 bool QuicConnection::CheckForTimeout() {
1740   QuicTime now = clock_->ApproximateNow();
1741   QuicTime time_of_last_packet = max(time_of_last_received_packet_,
1742                                      time_of_last_sent_new_packet_);
1743
1744   // |delta| can be < 0 as |now| is approximate time but |time_of_last_packet|
1745   // is accurate time. However, this should not change the behavior of
1746   // timeout handling.
1747   QuicTime::Delta delta = now.Subtract(time_of_last_packet);
1748   DVLOG(1) << ENDPOINT << "last packet "
1749            << time_of_last_packet.ToDebuggingValue()
1750            << " now:" << now.ToDebuggingValue()
1751            << " delta:" << delta.ToMicroseconds()
1752            << " network_timeout: " << idle_network_timeout_.ToMicroseconds();
1753   if (delta >= idle_network_timeout_) {
1754     DVLOG(1) << ENDPOINT << "Connection timedout due to no network activity.";
1755     SendConnectionClose(QUIC_CONNECTION_TIMED_OUT);
1756     return true;
1757   }
1758
1759   // Next timeout delta.
1760   QuicTime::Delta timeout = idle_network_timeout_.Subtract(delta);
1761
1762   if (!overall_connection_timeout_.IsInfinite()) {
1763     QuicTime::Delta connected_time = now.Subtract(creation_time_);
1764     DVLOG(1) << ENDPOINT << "connection time: "
1765              << connected_time.ToMilliseconds() << " overall timeout: "
1766              << overall_connection_timeout_.ToMilliseconds();
1767     if (connected_time >= overall_connection_timeout_) {
1768       DVLOG(1) << ENDPOINT <<
1769           "Connection timedout due to overall connection timeout.";
1770       SendConnectionClose(QUIC_CONNECTION_TIMED_OUT);
1771       return true;
1772     }
1773
1774     // Take the min timeout.
1775     QuicTime::Delta connection_timeout =
1776         overall_connection_timeout_.Subtract(connected_time);
1777     if (connection_timeout < timeout) {
1778       timeout = connection_timeout;
1779     }
1780   }
1781
1782   timeout_alarm_->Cancel();
1783   timeout_alarm_->Set(clock_->ApproximateNow().Add(timeout));
1784   return false;
1785 }
1786
1787 QuicConnection::ScopedPacketBundler::ScopedPacketBundler(
1788     QuicConnection* connection,
1789     AckBundling send_ack)
1790     : connection_(connection),
1791       already_in_batch_mode_(connection->packet_generator_.InBatchMode()) {
1792   // Move generator into batch mode. If caller wants us to include an ack,
1793   // check the delayed-ack timer to see if there's ack info to be sent.
1794   if (!already_in_batch_mode_) {
1795     DVLOG(1) << "Entering Batch Mode.";
1796     connection_->packet_generator_.StartBatchOperations();
1797   }
1798   // Bundle an ack if the alarm is set or with every second packet if we need to
1799   // raise the peer's least unacked.
1800   bool ack_pending =
1801       connection_->ack_alarm_->IsSet() || connection_->stop_waiting_count_ > 1;
1802   if (send_ack == SEND_ACK || (send_ack == BUNDLE_PENDING_ACK && ack_pending)) {
1803     DVLOG(1) << "Bundling ack with outgoing packet.";
1804     connection_->SendAck();
1805   }
1806 }
1807
1808 QuicConnection::ScopedPacketBundler::~ScopedPacketBundler() {
1809   // If we changed the generator's batch state, restore original batch state.
1810   if (!already_in_batch_mode_) {
1811     DVLOG(1) << "Leaving Batch Mode.";
1812     connection_->packet_generator_.FinishBatchOperations();
1813   }
1814   DCHECK_EQ(already_in_batch_mode_,
1815             connection_->packet_generator_.InBatchMode());
1816 }
1817
1818 }  // namespace net