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_flags.h"
  26 #include "net/quic/quic_utils.h"
  27
  28 using base::StringPiece;
  29 using base::hash_map;
  30 using base::hash_set;
  31 using std::list;
  32 using std::make_pair;
  33 using std::max;
  34 using std::min;
  35 using std::numeric_limits;
  36 using std::set;
  37 using std::string;
  38 using std::vector;
  39
  40 namespace net {
  41
  42 class QuicDecrypter;
  43 class QuicEncrypter;
  44
  45 namespace {
  46
  47 // The largest gap in packets we'll accept without closing the connection.
  48 // This will likely have to be tuned.
  49 const QuicPacketSequenceNumber kMaxPacketGap = 5000;
  50
  51 // Limit the number of FEC groups to two.  If we get enough out of order packets
  52 // that this becomes limiting, we can revisit.
  53 const size_t kMaxFecGroups = 2;
  54
  55 // Limit the number of undecryptable packets we buffer in
  56 // expectation of the CHLO/SHLO arriving.
  57 const size_t kMaxUndecryptablePackets = 10;
  58
  59 bool Near(QuicPacketSequenceNumber a, QuicPacketSequenceNumber b) {
  60   QuicPacketSequenceNumber delta = (a > b) ? a - b : b - a;
  61   return delta <= kMaxPacketGap;
  62 }
  63
  64 // An alarm that is scheduled to send an ack if a timeout occurs.
  65 class AckAlarm : public QuicAlarm::Delegate {
  66  public:
  67   explicit AckAlarm(QuicConnection* connection)
  68       : connection_(connection) {
  69   }
  70
  71   virtual QuicTime OnAlarm() OVERRIDE {
  72     connection_->SendAck();
  73     return QuicTime::Zero();
  74   }
  75
  76  private:
  77   QuicConnection* connection_;
  78
  79   DISALLOW_COPY_AND_ASSIGN(AckAlarm);
  80 };
  81
  82 // This alarm will be scheduled any time a data-bearing packet is sent out.
  83 // When the alarm goes off, the connection checks to see if the oldest packets
  84 // have been acked, and retransmit them if they have not.
  85 class RetransmissionAlarm : public QuicAlarm::Delegate {
  86  public:
  87   explicit RetransmissionAlarm(QuicConnection* connection)
  88       : connection_(connection) {
  89   }
  90
  91   virtual QuicTime OnAlarm() OVERRIDE {
  92     connection_->OnRetransmissionTimeout();
  93     return QuicTime::Zero();
  94   }
  95
  96  private:
  97   QuicConnection* connection_;
  98
  99   DISALLOW_COPY_AND_ASSIGN(RetransmissionAlarm);
 100 };
 101
 102 // An alarm that is scheduled when the sent scheduler requires a
 103 // a delay before sending packets and fires when the packet may be sent.
 104 class SendAlarm : public QuicAlarm::Delegate {
 105  public:
 106   explicit SendAlarm(QuicConnection* connection)
 107       : connection_(connection) {
 108   }
 109
 110   virtual QuicTime OnAlarm() OVERRIDE {
 111     connection_->WriteIfNotBlocked();
 112     // Never reschedule the alarm, since CanWrite does that.
 113     return QuicTime::Zero();
 114   }
 115
 116  private:
 117   QuicConnection* connection_;
 118
 119   DISALLOW_COPY_AND_ASSIGN(SendAlarm);
 120 };
 121
 122 class TimeoutAlarm : public QuicAlarm::Delegate {
 123  public:
 124   explicit TimeoutAlarm(QuicConnection* connection)
 125       : connection_(connection) {
 126   }
 127
 128   virtual QuicTime OnAlarm() OVERRIDE {
 129     connection_->CheckForTimeout();
 130     // Never reschedule the alarm, since CheckForTimeout does that.
 131     return QuicTime::Zero();
 132   }
 133
 134  private:
 135   QuicConnection* connection_;
 136
 137   DISALLOW_COPY_AND_ASSIGN(TimeoutAlarm);
 138 };
 139
 140 class PingAlarm : public QuicAlarm::Delegate {
 141  public:
 142   explicit PingAlarm(QuicConnection* connection)
 143       : connection_(connection) {
 144   }
 145
 146   virtual QuicTime OnAlarm() OVERRIDE {
 147     connection_->SendPing();
 148     return QuicTime::Zero();
 149   }
 150
 151  private:
 152   QuicConnection* connection_;
 153
 154   DISALLOW_COPY_AND_ASSIGN(PingAlarm);
 155 };
 156
 157 QuicConnection::PacketType GetPacketType(
 158     const RetransmittableFrames* retransmittable_frames) {
 159   if (!retransmittable_frames) {
 160     return QuicConnection::NORMAL;
 161   }
 162   for (size_t i = 0; i < retransmittable_frames->frames().size(); ++i) {
 163     if (retransmittable_frames->frames()[i].type == CONNECTION_CLOSE_FRAME) {
 164       return QuicConnection::CONNECTION_CLOSE;
 165     }
 166   }
 167   return QuicConnection::NORMAL;
 168 }
 169
 170 }  // namespace
 171
 172 QuicConnection::QueuedPacket::QueuedPacket(SerializedPacket packet,
 173                                            EncryptionLevel level,
 174                                            TransmissionType transmission_type)
 175   : sequence_number(packet.sequence_number),
 176     packet(packet.packet),
 177     encryption_level(level),
 178     transmission_type(transmission_type),
 179     retransmittable((transmission_type != NOT_RETRANSMISSION ||
 180                      packet.retransmittable_frames != NULL) ?
 181                          HAS_RETRANSMITTABLE_DATA : NO_RETRANSMITTABLE_DATA),
 182     handshake(packet.retransmittable_frames == NULL ?
 183       NOT_HANDSHAKE : packet.retransmittable_frames->HasCryptoHandshake()),
 184     type(GetPacketType(packet.retransmittable_frames)),
 185     length(packet.packet->length()) {
 186 }
 187
 188 #define ENDPOINT (is_server_ ? "Server: " : " Client: ")
 189
 190 QuicConnection::QuicConnection(QuicConnectionId connection_id,
 191                                IPEndPoint address,
 192                                QuicConnectionHelperInterface* helper,
 193                                const PacketWriterFactory& writer_factory,
 194                                bool owns_writer,
 195                                bool is_server,
 196                                const QuicVersionVector& supported_versions)
 197     : framer_(supported_versions, helper->GetClock()->ApproximateNow(),
 198               is_server),
 199       helper_(helper),
 200       writer_(writer_factory.Create(this)),
 201       owns_writer_(owns_writer),
 202       encryption_level_(ENCRYPTION_NONE),
 203       clock_(helper->GetClock()),
 204       random_generator_(helper->GetRandomGenerator()),
 205       connection_id_(connection_id),
 206       peer_address_(address),
 207       migrating_peer_port_(0),
 208       last_packet_revived_(false),
 209       last_size_(0),
 210       last_decrypted_packet_level_(ENCRYPTION_NONE),
 211       largest_seen_packet_with_ack_(0),
 212       largest_seen_packet_with_stop_waiting_(0),
 213       pending_version_negotiation_packet_(false),
 214       received_packet_manager_(&stats_),
 215       ack_queued_(false),
 216       stop_waiting_count_(0),
 217       ack_alarm_(helper->CreateAlarm(new AckAlarm(this))),
 218       retransmission_alarm_(helper->CreateAlarm(new RetransmissionAlarm(this))),
 219       send_alarm_(helper->CreateAlarm(new SendAlarm(this))),
 220       resume_writes_alarm_(helper->CreateAlarm(new SendAlarm(this))),
 221       timeout_alarm_(helper->CreateAlarm(new TimeoutAlarm(this))),
 222       ping_alarm_(helper->CreateAlarm(new PingAlarm(this))),
 223       packet_generator_(connection_id_, &framer_, random_generator_, this),
 224       idle_network_timeout_(
 225           QuicTime::Delta::FromSeconds(kDefaultInitialTimeoutSecs)),
 226       overall_connection_timeout_(QuicTime::Delta::Infinite()),
 227       time_of_last_received_packet_(clock_->ApproximateNow()),
 228       time_of_last_sent_new_packet_(clock_->ApproximateNow()),
 229       sequence_number_of_last_sent_packet_(0),
 230       sent_packet_manager_(
 231           is_server, clock_, &stats_,
 232           FLAGS_quic_use_bbr_congestion_control ? kBBR : kCubic,
 233           FLAGS_quic_use_time_loss_detection ? kTime : kNack),
 234       version_negotiation_state_(START_NEGOTIATION),
 235       is_server_(is_server),
 236       connected_(true),
 237       peer_ip_changed_(false),
 238       peer_port_changed_(false),
 239       self_ip_changed_(false),
 240       self_port_changed_(false) {
 241 #if 0
 242   // TODO(rtenneti): Should we enable this code in chromium?
 243   if (!is_server_) {
 244     // Pacing will be enabled if the client negotiates it.
 245     sent_packet_manager_.MaybeEnablePacing();
 246   }
 247 #endif
 248   DVLOG(1) << ENDPOINT << "Created connection with connection_id: "
 249            << connection_id;
 250   timeout_alarm_->Set(clock_->ApproximateNow().Add(idle_network_timeout_));
 251   framer_.set_visitor(this);
 252   framer_.set_received_entropy_calculator(&received_packet_manager_);
 253   stats_.connection_creation_time = clock_->ApproximateNow();
 254   sent_packet_manager_.set_network_change_visitor(this);
 255 }
 256
 257 QuicConnection::~QuicConnection() {
 258   if (owns_writer_) {
 259     delete writer_;
 260   }
 261   STLDeleteElements(&undecryptable_packets_);
 262   STLDeleteValues(&group_map_);
 263   for (QueuedPacketList::iterator it = queued_packets_.begin();
 264        it != queued_packets_.end(); ++it) {
 265     delete it->packet;
 266   }
 267 }
 268
 269 void QuicConnection::SetFromConfig(const QuicConfig& config) {
 270   SetIdleNetworkTimeout(config.idle_connection_state_lifetime());
 271   sent_packet_manager_.SetFromConfig(config);
 272 }
 273
 274 bool QuicConnection::SelectMutualVersion(
 275     const QuicVersionVector& available_versions) {
 276   // Try to find the highest mutual version by iterating over supported
 277   // versions, starting with the highest, and breaking out of the loop once we
 278   // find a matching version in the provided available_versions vector.
 279   const QuicVersionVector& supported_versions = framer_.supported_versions();
 280   for (size_t i = 0; i < supported_versions.size(); ++i) {
 281     const QuicVersion& version = supported_versions[i];
 282     if (std::find(available_versions.begin(), available_versions.end(),
 283                   version) != available_versions.end()) {
 284       framer_.set_version(version);
 285       return true;
 286     }
 287   }
 288
 289   return false;
 290 }
 291
 292 void QuicConnection::OnError(QuicFramer* framer) {
 293   // Packets that we cannot decrypt are dropped.
 294   // TODO(rch): add stats to measure this.
 295   if (!connected_ || framer->error() == QUIC_DECRYPTION_FAILURE) {
 296     return;
 297   }
 298   SendConnectionCloseWithDetails(framer->error(), framer->detailed_error());
 299 }
 300
 301 void QuicConnection::OnPacket() {
 302   DCHECK(last_stream_frames_.empty() &&
 303          last_goaway_frames_.empty() &&
 304          last_window_update_frames_.empty() &&
 305          last_blocked_frames_.empty() &&
 306          last_rst_frames_.empty() &&
 307          last_ack_frames_.empty() &&
 308          last_congestion_frames_.empty() &&
 309          last_stop_waiting_frames_.empty());
 310 }
 311
 312 void QuicConnection::OnPublicResetPacket(
 313     const QuicPublicResetPacket& packet) {
 314   if (debug_visitor_.get() != NULL) {
 315     debug_visitor_->OnPublicResetPacket(packet);
 316   }
 317   CloseConnection(QUIC_PUBLIC_RESET, true);
 318
 319   DVLOG(1) << ENDPOINT << "Connection " << connection_id()
 320            << " closed via QUIC_PUBLIC_RESET from peer.";
 321 }
 322
 323 bool QuicConnection::OnProtocolVersionMismatch(QuicVersion received_version) {
 324   DVLOG(1) << ENDPOINT << "Received packet with mismatched version "
 325            << received_version;
 326   // TODO(satyamshekhar): Implement no server state in this mode.
 327   if (!is_server_) {
 328     LOG(DFATAL) << ENDPOINT << "Framer called OnProtocolVersionMismatch. "
 329                 << "Closing connection.";
 330     CloseConnection(QUIC_INTERNAL_ERROR, false);
 331     return false;
 332   }
 333   DCHECK_NE(version(), received_version);
 334
 335   if (debug_visitor_.get() != NULL) {
 336     debug_visitor_->OnProtocolVersionMismatch(received_version);
 337   }
 338
 339   switch (version_negotiation_state_) {
 340     case START_NEGOTIATION:
 341       if (!framer_.IsSupportedVersion(received_version)) {
 342         SendVersionNegotiationPacket();
 343         version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
 344         return false;
 345       }
 346       break;
 347
 348     case NEGOTIATION_IN_PROGRESS:
 349       if (!framer_.IsSupportedVersion(received_version)) {
 350         SendVersionNegotiationPacket();
 351         return false;
 352       }
 353       break;
 354
 355     case NEGOTIATED_VERSION:
 356       // Might be old packets that were sent by the client before the version
 357       // was negotiated. Drop these.
 358       return false;
 359
 360     default:
 361       DCHECK(false);
 362   }
 363
 364   version_negotiation_state_ = NEGOTIATED_VERSION;
 365   visitor_->OnSuccessfulVersionNegotiation(received_version);
 366   DVLOG(1) << ENDPOINT << "version negotiated " << received_version;
 367
 368   // Store the new version.
 369   framer_.set_version(received_version);
 370
 371   // TODO(satyamshekhar): Store the sequence number of this packet and close the
 372   // connection if we ever received a packet with incorrect version and whose
 373   // sequence number is greater.
 374   return true;
 375 }
 376
 377 // Handles version negotiation for client connection.
 378 void QuicConnection::OnVersionNegotiationPacket(
 379     const QuicVersionNegotiationPacket& packet) {
 380   if (is_server_) {
 381     LOG(DFATAL) << ENDPOINT << "Framer parsed VersionNegotiationPacket."
 382                 << " Closing connection.";
 383     CloseConnection(QUIC_INTERNAL_ERROR, false);
 384     return;
 385   }
 386   if (debug_visitor_.get() != NULL) {
 387     debug_visitor_->OnVersionNegotiationPacket(packet);
 388   }
 389
 390   if (version_negotiation_state_ != START_NEGOTIATION) {
 391     // Possibly a duplicate version negotiation packet.
 392     return;
 393   }
 394
 395   if (std::find(packet.versions.begin(),
 396                 packet.versions.end(), version()) !=
 397       packet.versions.end()) {
 398     DLOG(WARNING) << ENDPOINT << "The server already supports our version. "
 399                   << "It should have accepted our connection.";
 400     // Just drop the connection.
 401     CloseConnection(QUIC_INVALID_VERSION_NEGOTIATION_PACKET, false);
 402     return;
 403   }
 404
 405   if (!SelectMutualVersion(packet.versions)) {
 406     SendConnectionCloseWithDetails(QUIC_INVALID_VERSION,
 407                                    "no common version found");
 408     return;
 409   }
 410
 411   DVLOG(1) << ENDPOINT
 412            << "Negotiated version: " << QuicVersionToString(version());
 413   server_supported_versions_ = packet.versions;
 414   version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
 415   RetransmitUnackedPackets(ALL_PACKETS);
 416 }
 417
 418 void QuicConnection::OnRevivedPacket() {
 419 }
 420
 421 bool QuicConnection::OnUnauthenticatedPublicHeader(
 422     const QuicPacketPublicHeader& header) {
 423   return true;
 424 }
 425
 426 bool QuicConnection::OnUnauthenticatedHeader(const QuicPacketHeader& header) {
 427   return true;
 428 }
 429
 430 void QuicConnection::OnDecryptedPacket(EncryptionLevel level) {
 431   last_decrypted_packet_level_ = level;
 432 }
 433
 434 bool QuicConnection::OnPacketHeader(const QuicPacketHeader& header) {
 435   if (debug_visitor_.get() != NULL) {
 436     debug_visitor_->OnPacketHeader(header);
 437   }
 438
 439   if (!ProcessValidatedPacket()) {
 440     return false;
 441   }
 442
 443   // Will be decrement below if we fall through to return true;
 444   ++stats_.packets_dropped;
 445
 446   if (header.public_header.connection_id != connection_id_) {
 447     DVLOG(1) << ENDPOINT << "Ignoring packet from unexpected ConnectionId: "
 448              << header.public_header.connection_id << " instead of "
 449              << connection_id_;
 450     if (debug_visitor_.get() != NULL) {
 451       debug_visitor_->OnIncorrectConnectionId(
 452           header.public_header.connection_id);
 453     }
 454     return false;
 455   }
 456
 457   if (!Near(header.packet_sequence_number,
 458             last_header_.packet_sequence_number)) {
 459     DVLOG(1) << ENDPOINT << "Packet " << header.packet_sequence_number
 460              << " out of bounds.  Discarding";
 461     SendConnectionCloseWithDetails(QUIC_INVALID_PACKET_HEADER,
 462                                    "Packet sequence number out of bounds");
 463     return false;
 464   }
 465
 466   // If this packet has already been seen, or that the sender
 467   // has told us will not be retransmitted, then stop processing the packet.
 468   if (!received_packet_manager_.IsAwaitingPacket(
 469           header.packet_sequence_number)) {
 470     DVLOG(1) << ENDPOINT << "Packet " << header.packet_sequence_number
 471              << " no longer being waited for.  Discarding.";
 472     if (debug_visitor_.get() != NULL) {
 473       debug_visitor_->OnDuplicatePacket(header.packet_sequence_number);
 474     }
 475     return false;
 476   }
 477
 478   if (version_negotiation_state_ != NEGOTIATED_VERSION) {
 479     if (is_server_) {
 480       if (!header.public_header.version_flag) {
 481         DLOG(WARNING) << ENDPOINT << "Packet " << header.packet_sequence_number
 482                       << " without version flag before version negotiated.";
 483         // Packets should have the version flag till version negotiation is
 484         // done.
 485         CloseConnection(QUIC_INVALID_VERSION, false);
 486         return false;
 487       } else {
 488         DCHECK_EQ(1u, header.public_header.versions.size());
 489         DCHECK_EQ(header.public_header.versions[0], version());
 490         version_negotiation_state_ = NEGOTIATED_VERSION;
 491         visitor_->OnSuccessfulVersionNegotiation(version());
 492       }
 493     } else {
 494       DCHECK(!header.public_header.version_flag);
 495       // If the client gets a packet without the version flag from the server
 496       // it should stop sending version since the version negotiation is done.
 497       packet_generator_.StopSendingVersion();
 498       version_negotiation_state_ = NEGOTIATED_VERSION;
 499       visitor_->OnSuccessfulVersionNegotiation(version());
 500     }
 501   }
 502
 503   DCHECK_EQ(NEGOTIATED_VERSION, version_negotiation_state_);
 504
 505   --stats_.packets_dropped;
 506   DVLOG(1) << ENDPOINT << "Received packet header: " << header;
 507   last_header_ = header;
 508   DCHECK(connected_);
 509   return true;
 510 }
 511
 512 void QuicConnection::OnFecProtectedPayload(StringPiece payload) {
 513   DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
 514   DCHECK_NE(0u, last_header_.fec_group);
 515   QuicFecGroup* group = GetFecGroup();
 516   if (group != NULL) {
 517     group->Update(last_decrypted_packet_level_, last_header_, payload);
 518   }
 519 }
 520
 521 bool QuicConnection::OnStreamFrame(const QuicStreamFrame& frame) {
 522   DCHECK(connected_);
 523   if (debug_visitor_.get() != NULL) {
 524     debug_visitor_->OnStreamFrame(frame);
 525   }
 526   if (frame.stream_id != kCryptoStreamId &&
 527       last_decrypted_packet_level_ == ENCRYPTION_NONE) {
 528     DLOG(WARNING) << ENDPOINT
 529                   << "Received an unencrypted data frame: closing connection";
 530     SendConnectionClose(QUIC_UNENCRYPTED_STREAM_DATA);
 531     return false;
 532   }
 533   last_stream_frames_.push_back(frame);
 534   return true;
 535 }
 536
 537 bool QuicConnection::OnAckFrame(const QuicAckFrame& incoming_ack) {
 538   DCHECK(connected_);
 539   if (debug_visitor_.get() != NULL) {
 540     debug_visitor_->OnAckFrame(incoming_ack);
 541   }
 542   DVLOG(1) << ENDPOINT << "OnAckFrame: " << incoming_ack;
 543
 544   if (last_header_.packet_sequence_number <= largest_seen_packet_with_ack_) {
 545     DVLOG(1) << ENDPOINT << "Received an old ack frame: ignoring";
 546     return true;
 547   }
 548
 549   if (!ValidateAckFrame(incoming_ack)) {
 550     SendConnectionClose(QUIC_INVALID_ACK_DATA);
 551     return false;
 552   }
 553
 554   last_ack_frames_.push_back(incoming_ack);
 555   return connected_;
 556 }
 557
 558 void QuicConnection::ProcessAckFrame(const QuicAckFrame& incoming_ack) {
 559   largest_seen_packet_with_ack_ = last_header_.packet_sequence_number;
 560   sent_packet_manager_.OnIncomingAck(incoming_ack,
 561                                      time_of_last_received_packet_);
 562   sent_entropy_manager_.ClearEntropyBefore(
 563       sent_packet_manager_.least_packet_awaited_by_peer() - 1);
 564   if (sent_packet_manager_.HasPendingRetransmissions()) {
 565     WriteIfNotBlocked();
 566   }
 567
 568   // Always reset the retransmission alarm when an ack comes in, since we now
 569   // have a better estimate of the current rtt than when it was set.
 570   QuicTime retransmission_time = sent_packet_manager_.GetRetransmissionTime();
 571   retransmission_alarm_->Update(retransmission_time,
 572                                 QuicTime::Delta::FromMilliseconds(1));
 573 }
 574
 575 void QuicConnection::ProcessStopWaitingFrame(
 576     const QuicStopWaitingFrame& stop_waiting) {
 577   largest_seen_packet_with_stop_waiting_ = last_header_.packet_sequence_number;
 578   received_packet_manager_.UpdatePacketInformationSentByPeer(stop_waiting);
 579   // Possibly close any FecGroups which are now irrelevant.
 580   CloseFecGroupsBefore(stop_waiting.least_unacked + 1);
 581 }
 582
 583 bool QuicConnection::OnCongestionFeedbackFrame(
 584     const QuicCongestionFeedbackFrame& feedback) {
 585   DCHECK(connected_);
 586   if (debug_visitor_.get() != NULL) {
 587     debug_visitor_->OnCongestionFeedbackFrame(feedback);
 588   }
 589   last_congestion_frames_.push_back(feedback);
 590   return connected_;
 591 }
 592
 593 bool QuicConnection::OnStopWaitingFrame(const QuicStopWaitingFrame& frame) {
 594   DCHECK(connected_);
 595
 596   if (last_header_.packet_sequence_number <=
 597       largest_seen_packet_with_stop_waiting_) {
 598     DVLOG(1) << ENDPOINT << "Received an old stop waiting frame: ignoring";
 599     return true;
 600   }
 601
 602   if (!ValidateStopWaitingFrame(frame)) {
 603     SendConnectionClose(QUIC_INVALID_STOP_WAITING_DATA);
 604     return false;
 605   }
 606
 607   if (debug_visitor_.get() != NULL) {
 608     debug_visitor_->OnStopWaitingFrame(frame);
 609   }
 610
 611   last_stop_waiting_frames_.push_back(frame);
 612   return connected_;
 613 }
 614
 615 bool QuicConnection::OnPingFrame(const QuicPingFrame& frame) {
 616   DCHECK(connected_);
 617   if (debug_visitor_.get() != NULL) {
 618     debug_visitor_->OnPingFrame(frame);
 619   }
 620   return true;
 621 }
 622
 623 bool QuicConnection::ValidateAckFrame(const QuicAckFrame& incoming_ack) {
 624   if (incoming_ack.largest_observed > packet_generator_.sequence_number()) {
 625     DLOG(ERROR) << ENDPOINT << "Peer's observed unsent packet:"
 626                 << incoming_ack.largest_observed << " vs "
 627                 << packet_generator_.sequence_number();
 628     // We got an error for data we have not sent.  Error out.
 629     return false;
 630   }
 631
 632   if (incoming_ack.largest_observed < sent_packet_manager_.largest_observed()) {
 633     DLOG(ERROR) << ENDPOINT << "Peer's largest_observed packet decreased:"
 634                 << incoming_ack.largest_observed << " vs "
 635                 << sent_packet_manager_.largest_observed();
 636     // A new ack has a diminished largest_observed value.  Error out.
 637     // If this was an old packet, we wouldn't even have checked.
 638     return false;
 639   }
 640
 641   if (!incoming_ack.missing_packets.empty() &&
 642       *incoming_ack.missing_packets.rbegin() > incoming_ack.largest_observed) {
 643     DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
 644                 << *incoming_ack.missing_packets.rbegin()
 645                 << " which is greater than largest observed: "
 646                 << incoming_ack.largest_observed;
 647     return false;
 648   }
 649
 650   if (!incoming_ack.missing_packets.empty() &&
 651       *incoming_ack.missing_packets.begin() <
 652       sent_packet_manager_.least_packet_awaited_by_peer()) {
 653     DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
 654                 << *incoming_ack.missing_packets.begin()
 655                 << " which is smaller than least_packet_awaited_by_peer_: "
 656                 << sent_packet_manager_.least_packet_awaited_by_peer();
 657     return false;
 658   }
 659
 660   if (!sent_entropy_manager_.IsValidEntropy(
 661           incoming_ack.largest_observed,
 662           incoming_ack.missing_packets,
 663           incoming_ack.entropy_hash)) {
 664     DLOG(ERROR) << ENDPOINT << "Peer sent invalid entropy.";
 665     return false;
 666   }
 667
 668   for (SequenceNumberSet::const_iterator iter =
 669            incoming_ack.revived_packets.begin();
 670        iter != incoming_ack.revived_packets.end(); ++iter) {
 671     if (!ContainsKey(incoming_ack.missing_packets, *iter)) {
 672       DLOG(ERROR) << ENDPOINT
 673                   << "Peer specified revived packet which was not missing.";
 674       return false;
 675     }
 676   }
 677   return true;
 678 }
 679
 680 bool QuicConnection::ValidateStopWaitingFrame(
 681     const QuicStopWaitingFrame& stop_waiting) {
 682   if (stop_waiting.least_unacked <
 683       received_packet_manager_.peer_least_packet_awaiting_ack()) {
 684     DLOG(ERROR) << ENDPOINT << "Peer's sent low least_unacked: "
 685                 << stop_waiting.least_unacked << " vs "
 686                 << received_packet_manager_.peer_least_packet_awaiting_ack();
 687     // We never process old ack frames, so this number should only increase.
 688     return false;
 689   }
 690
 691   if (stop_waiting.least_unacked >
 692       last_header_.packet_sequence_number) {
 693     DLOG(ERROR) << ENDPOINT << "Peer sent least_unacked:"
 694                 << stop_waiting.least_unacked
 695                 << " greater than the enclosing packet sequence number:"
 696                 << last_header_.packet_sequence_number;
 697     return false;
 698   }
 699
 700   return true;
 701 }
 702
 703 void QuicConnection::OnFecData(const QuicFecData& fec) {
 704   DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
 705   DCHECK_NE(0u, last_header_.fec_group);
 706   QuicFecGroup* group = GetFecGroup();
 707   if (group != NULL) {
 708     group->UpdateFec(last_decrypted_packet_level_,
 709                      last_header_.packet_sequence_number, fec);
 710   }
 711 }
 712
 713 bool QuicConnection::OnRstStreamFrame(const QuicRstStreamFrame& frame) {
 714   DCHECK(connected_);
 715   if (debug_visitor_.get() != NULL) {
 716     debug_visitor_->OnRstStreamFrame(frame);
 717   }
 718   DVLOG(1) << ENDPOINT << "Stream reset with error "
 719            << QuicUtils::StreamErrorToString(frame.error_code);
 720   last_rst_frames_.push_back(frame);
 721   return connected_;
 722 }
 723
 724 bool QuicConnection::OnConnectionCloseFrame(
 725     const QuicConnectionCloseFrame& frame) {
 726   DCHECK(connected_);
 727   if (debug_visitor_.get() != NULL) {
 728     debug_visitor_->OnConnectionCloseFrame(frame);
 729   }
 730   DVLOG(1) << ENDPOINT << "Connection " << connection_id()
 731            << " closed with error "
 732            << QuicUtils::ErrorToString(frame.error_code)
 733            << " " << frame.error_details;
 734   last_close_frames_.push_back(frame);
 735   return connected_;
 736 }
 737
 738 bool QuicConnection::OnGoAwayFrame(const QuicGoAwayFrame& frame) {
 739   DCHECK(connected_);
 740   if (debug_visitor_.get() != NULL) {
 741     debug_visitor_->OnGoAwayFrame(frame);
 742   }
 743   DVLOG(1) << ENDPOINT << "Go away received with error "
 744            << QuicUtils::ErrorToString(frame.error_code)
 745            << " and reason:" << frame.reason_phrase;
 746   last_goaway_frames_.push_back(frame);
 747   return connected_;
 748 }
 749
 750 bool QuicConnection::OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) {
 751   DCHECK(connected_);
 752   if (debug_visitor_.get() != NULL) {
 753     debug_visitor_->OnWindowUpdateFrame(frame);
 754   }
 755   DVLOG(1) << ENDPOINT << "WindowUpdate received for stream: "
 756            << frame.stream_id << " with byte offset: " << frame.byte_offset;
 757   last_window_update_frames_.push_back(frame);
 758   return connected_;
 759 }
 760
 761 bool QuicConnection::OnBlockedFrame(const QuicBlockedFrame& frame) {
 762   DCHECK(connected_);
 763   if (debug_visitor_.get() != NULL) {
 764     debug_visitor_->OnBlockedFrame(frame);
 765   }
 766   DVLOG(1) << ENDPOINT << "Blocked frame received for stream: "
 767            << frame.stream_id;
 768   last_blocked_frames_.push_back(frame);
 769   return connected_;
 770 }
 771
 772 void QuicConnection::OnPacketComplete() {
 773   // Don't do anything if this packet closed the connection.
 774   if (!connected_) {
 775     ClearLastFrames();
 776     return;
 777   }
 778
 779   DVLOG(1) << ENDPOINT << (last_packet_revived_ ? "Revived" : "Got")
 780            << " packet " << last_header_.packet_sequence_number
 781            << " with " << last_ack_frames_.size() << " acks, "
 782            << last_congestion_frames_.size() << " congestions, "
 783            << last_stop_waiting_frames_.size() << " stop_waiting, "
 784            << last_goaway_frames_.size() << " goaways, "
 785            << last_window_update_frames_.size() << " window updates, "
 786            << last_blocked_frames_.size() << " blocked, "
 787            << last_rst_frames_.size() << " rsts, "
 788            << last_close_frames_.size() << " closes, "
 789            << last_stream_frames_.size()
 790            << " stream frames for "
 791            << last_header_.public_header.connection_id;
 792
 793   // Call MaybeQueueAck() before recording the received packet, since we want
 794   // to trigger an ack if the newly received packet was previously missing.
 795   MaybeQueueAck();
 796
 797   // Record received or revived packet to populate ack info correctly before
 798   // processing stream frames, since the processing may result in a response
 799   // packet with a bundled ack.
 800   if (last_packet_revived_) {
 801     received_packet_manager_.RecordPacketRevived(
 802         last_header_.packet_sequence_number);
 803   } else {
 804     received_packet_manager_.RecordPacketReceived(
 805         last_size_, last_header_, time_of_last_received_packet_);
 806   }
 807
 808   if (!last_stream_frames_.empty()) {
 809     visitor_->OnStreamFrames(last_stream_frames_);
 810   }
 811
 812   for (size_t i = 0; i < last_stream_frames_.size(); ++i) {
 813     stats_.stream_bytes_received +=
 814         last_stream_frames_[i].data.TotalBufferSize();
 815   }
 816
 817   // Process window updates, blocked, stream resets, acks, then congestion
 818   // feedback.
 819   if (!last_window_update_frames_.empty()) {
 820     visitor_->OnWindowUpdateFrames(last_window_update_frames_);
 821   }
 822   if (!last_blocked_frames_.empty()) {
 823     visitor_->OnBlockedFrames(last_blocked_frames_);
 824   }
 825   for (size_t i = 0; i < last_goaway_frames_.size(); ++i) {
 826     visitor_->OnGoAway(last_goaway_frames_[i]);
 827   }
 828   for (size_t i = 0; i < last_rst_frames_.size(); ++i) {
 829     visitor_->OnRstStream(last_rst_frames_[i]);
 830   }
 831   for (size_t i = 0; i < last_ack_frames_.size(); ++i) {
 832     ProcessAckFrame(last_ack_frames_[i]);
 833   }
 834   for (size_t i = 0; i < last_congestion_frames_.size(); ++i) {
 835     sent_packet_manager_.OnIncomingQuicCongestionFeedbackFrame(
 836         last_congestion_frames_[i], time_of_last_received_packet_);
 837   }
 838   for (size_t i = 0; i < last_stop_waiting_frames_.size(); ++i) {
 839     ProcessStopWaitingFrame(last_stop_waiting_frames_[i]);
 840   }
 841   if (!last_close_frames_.empty()) {
 842     CloseConnection(last_close_frames_[0].error_code, true);
 843     DCHECK(!connected_);
 844   }
 845
 846   // If there are new missing packets to report, send an ack immediately.
 847   if (received_packet_manager_.HasNewMissingPackets()) {
 848     ack_queued_ = true;
 849     ack_alarm_->Cancel();
 850   }
 851
 852   UpdateStopWaitingCount();
 853
 854   ClearLastFrames();
 855 }
 856
 857 void QuicConnection::MaybeQueueAck() {
 858   // If the incoming packet was missing, send an ack immediately.
 859   ack_queued_ = received_packet_manager_.IsMissing(
 860       last_header_.packet_sequence_number);
 861
 862   if (!ack_queued_ && ShouldLastPacketInstigateAck()) {
 863     if (ack_alarm_->IsSet()) {
 864       ack_queued_ = true;
 865     } else {
 866       // Send an ack much more quickly for crypto handshake packets.
 867       QuicTime::Delta delayed_ack_time = sent_packet_manager_.DelayedAckTime();
 868       if (last_stream_frames_.size() == 1 &&
 869           last_stream_frames_[0].stream_id == kCryptoStreamId) {
 870         delayed_ack_time = QuicTime::Delta::Zero();
 871       }
 872       ack_alarm_->Set(clock_->ApproximateNow().Add(delayed_ack_time));
 873       DVLOG(1) << "Ack timer set; next packet or timer will trigger ACK.";
 874     }
 875   }
 876
 877   if (ack_queued_) {
 878     ack_alarm_->Cancel();
 879   }
 880 }
 881
 882 void QuicConnection::ClearLastFrames() {
 883   last_stream_frames_.clear();
 884   last_goaway_frames_.clear();
 885   last_window_update_frames_.clear();
 886   last_blocked_frames_.clear();
 887   last_rst_frames_.clear();
 888   last_ack_frames_.clear();
 889   last_stop_waiting_frames_.clear();
 890   last_congestion_frames_.clear();
 891 }
 892
 893 QuicAckFrame* QuicConnection::CreateAckFrame() {
 894   QuicAckFrame* outgoing_ack = new QuicAckFrame();
 895   received_packet_manager_.UpdateReceivedPacketInfo(
 896       outgoing_ack, clock_->ApproximateNow());
 897   DVLOG(1) << ENDPOINT << "Creating ack frame: " << *outgoing_ack;
 898   return outgoing_ack;
 899 }
 900
 901 QuicCongestionFeedbackFrame* QuicConnection::CreateFeedbackFrame() {
 902   return new QuicCongestionFeedbackFrame(outgoing_congestion_feedback_);
 903 }
 904
 905 QuicStopWaitingFrame* QuicConnection::CreateStopWaitingFrame() {
 906   QuicStopWaitingFrame stop_waiting;
 907   UpdateStopWaiting(&stop_waiting);
 908   return new QuicStopWaitingFrame(stop_waiting);
 909 }
 910
 911 bool QuicConnection::ShouldLastPacketInstigateAck() const {
 912   if (!last_stream_frames_.empty() ||
 913       !last_goaway_frames_.empty() ||
 914       !last_rst_frames_.empty() ||
 915       !last_window_update_frames_.empty() ||
 916       !last_blocked_frames_.empty()) {
 917     return true;
 918   }
 919
 920   if (!last_ack_frames_.empty() && last_ack_frames_.back().is_truncated) {
 921     return true;
 922   }
 923   return false;
 924 }
 925
 926 void QuicConnection::UpdateStopWaitingCount() {
 927   if (last_ack_frames_.empty()) {
 928     return;
 929   }
 930
 931   // If the peer is still waiting for a packet that we are no longer planning to
 932   // send, send an ack to raise the high water mark.
 933   if (!last_ack_frames_.back().missing_packets.empty() &&
 934       GetLeastUnacked() > *last_ack_frames_.back().missing_packets.begin()) {
 935     ++stop_waiting_count_;
 936   } else {
 937     stop_waiting_count_ = 0;
 938   }
 939 }
 940
 941 QuicPacketSequenceNumber QuicConnection::GetLeastUnacked() const {
 942   return sent_packet_manager_.HasUnackedPackets() ?
 943       sent_packet_manager_.GetLeastUnackedSentPacket() :
 944       packet_generator_.sequence_number() + 1;
 945 }
 946
 947 void QuicConnection::MaybeSendInResponseToPacket() {
 948   if (!connected_) {
 949     return;
 950   }
 951   ScopedPacketBundler bundler(this, ack_queued_ ? SEND_ACK : NO_ACK);
 952
 953   // Now that we have received an ack, we might be able to send packets which
 954   // are queued locally, or drain streams which are blocked.
 955   if (CanWrite(HAS_RETRANSMITTABLE_DATA)) {
 956     OnCanWrite();
 957   }
 958 }
 959
 960 void QuicConnection::SendVersionNegotiationPacket() {
 961   // TODO(alyssar): implement zero server state negotiation.
 962   pending_version_negotiation_packet_ = true;
 963   if (writer_->IsWriteBlocked()) {
 964     visitor_->OnWriteBlocked();
 965     return;
 966   }
 967   DVLOG(1) << ENDPOINT << "Sending version negotiation packet: {"
 968            << QuicVersionVectorToString(framer_.supported_versions()) << "}";
 969   scoped_ptr<QuicEncryptedPacket> version_packet(
 970       packet_generator_.SerializeVersionNegotiationPacket(
 971           framer_.supported_versions()));
 972   WriteResult result = writer_->WritePacket(
 973       version_packet->data(), version_packet->length(),
 974       self_address().address(), peer_address());
 975
 976   if (result.status == WRITE_STATUS_ERROR) {
 977     // We can't send an error as the socket is presumably borked.
 978     CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
 979     return;
 980   }
 981   if (result.status == WRITE_STATUS_BLOCKED) {
 982     visitor_->OnWriteBlocked();
 983     if (writer_->IsWriteBlockedDataBuffered()) {
 984       pending_version_negotiation_packet_ = false;
 985     }
 986     return;
 987   }
 988
 989   pending_version_negotiation_packet_ = false;
 990 }
 991
 992 QuicConsumedData QuicConnection::SendStreamData(
 993     QuicStreamId id,
 994     const IOVector& data,
 995     QuicStreamOffset offset,
 996     bool fin,
 997     FecProtection fec_protection,
 998     QuicAckNotifier::DelegateInterface* delegate) {
 999   if (!fin && data.Empty()) {
1000     LOG(DFATAL) << "Attempt to send empty stream frame";
1001   }
1002
1003   // This notifier will be owned by the AckNotifierManager (or deleted below if
1004   // no data or FIN was consumed).
1005   QuicAckNotifier* notifier = NULL;
1006   if (delegate) {
1007     notifier = new QuicAckNotifier(delegate);
1008   }
1009
1010   // Opportunistically bundle an ack with every outgoing packet.
1011   // Particularly, we want to bundle with handshake packets since we don't know
1012   // which decrypter will be used on an ack packet following a handshake
1013   // packet (a handshake packet from client to server could result in a REJ or a
1014   // SHLO from the server, leading to two different decrypters at the server.)
1015   //
1016   // TODO(jri): Note that ConsumeData may cause a response packet to be sent.
1017   // We may end up sending stale ack information if there are undecryptable
1018   // packets hanging around and/or there are revivable packets which may get
1019   // handled after this packet is sent. Change ScopedPacketBundler to do the
1020   // right thing: check ack_queued_, and then check undecryptable packets and
1021   // also if there is possibility of revival. Only bundle an ack if there's no
1022   // processing left that may cause received_info_ to change.
1023   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1024   QuicConsumedData consumed_data =
1025       packet_generator_.ConsumeData(id, data, offset, fin, fec_protection,
1026                                     notifier);
1027
1028   if (notifier &&
1029       (consumed_data.bytes_consumed == 0 && !consumed_data.fin_consumed)) {
1030     // No data was consumed, nor was a fin consumed, so delete the notifier.
1031     delete notifier;
1032   }
1033
1034   return consumed_data;
1035 }
1036
1037 void QuicConnection::SendRstStream(QuicStreamId id,
1038                                    QuicRstStreamErrorCode error,
1039                                    QuicStreamOffset bytes_written) {
1040   // Opportunistically bundle an ack with this outgoing packet.
1041   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1042   packet_generator_.AddControlFrame(QuicFrame(new QuicRstStreamFrame(
1043       id, AdjustErrorForVersion(error, version()), bytes_written)));
1044 }
1045
1046 void QuicConnection::SendWindowUpdate(QuicStreamId id,
1047                                       QuicStreamOffset byte_offset) {
1048   // Opportunistically bundle an ack with this outgoing packet.
1049   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1050   packet_generator_.AddControlFrame(
1051       QuicFrame(new QuicWindowUpdateFrame(id, byte_offset)));
1052 }
1053
1054 void QuicConnection::SendBlocked(QuicStreamId id) {
1055   // Opportunistically bundle an ack with this outgoing packet.
1056   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1057   packet_generator_.AddControlFrame(QuicFrame(new QuicBlockedFrame(id)));
1058 }
1059
1060 const QuicConnectionStats& QuicConnection::GetStats() {
1061   // Update rtt and estimated bandwidth.
1062   stats_.min_rtt_us =
1063       sent_packet_manager_.GetRttStats()->min_rtt().ToMicroseconds();
1064   stats_.srtt_us =
1065       sent_packet_manager_.GetRttStats()->SmoothedRtt().ToMicroseconds();
1066   stats_.estimated_bandwidth =
1067       sent_packet_manager_.BandwidthEstimate().ToBytesPerSecond();
1068   stats_.congestion_window = sent_packet_manager_.GetCongestionWindow();
1069   stats_.slow_start_threshold = sent_packet_manager_.GetSlowStartThreshold();
1070   stats_.max_packet_size = packet_generator_.max_packet_length();
1071   return stats_;
1072 }
1073
1074 void QuicConnection::ProcessUdpPacket(const IPEndPoint& self_address,
1075                                       const IPEndPoint& peer_address,
1076                                       const QuicEncryptedPacket& packet) {
1077   if (!connected_) {
1078     return;
1079   }
1080   if (debug_visitor_.get() != NULL) {
1081     debug_visitor_->OnPacketReceived(self_address, peer_address, packet);
1082   }
1083   last_packet_revived_ = false;
1084   last_size_ = packet.length();
1085
1086   CheckForAddressMigration(self_address, peer_address);
1087
1088   stats_.bytes_received += packet.length();
1089   ++stats_.packets_received;
1090
1091   if (!framer_.ProcessPacket(packet)) {
1092     // If we are unable to decrypt this packet, it might be
1093     // because the CHLO or SHLO packet was lost.
1094     if (framer_.error() == QUIC_DECRYPTION_FAILURE) {
1095       if (encryption_level_ != ENCRYPTION_FORWARD_SECURE &&
1096           undecryptable_packets_.size() < kMaxUndecryptablePackets) {
1097         QueueUndecryptablePacket(packet);
1098       } else if (debug_visitor_.get() != NULL) {
1099         debug_visitor_->OnUndecryptablePacket();
1100       }
1101     }
1102     DVLOG(1) << ENDPOINT << "Unable to process packet.  Last packet processed: "
1103              << last_header_.packet_sequence_number;
1104     return;
1105   }
1106
1107   ++stats_.packets_processed;
1108   MaybeProcessUndecryptablePackets();
1109   MaybeProcessRevivedPacket();
1110   MaybeSendInResponseToPacket();
1111   SetPingAlarm();
1112 }
1113
1114 void QuicConnection::CheckForAddressMigration(
1115     const IPEndPoint& self_address, const IPEndPoint& peer_address) {
1116   peer_ip_changed_ = false;
1117   peer_port_changed_ = false;
1118   self_ip_changed_ = false;
1119   self_port_changed_ = false;
1120
1121   if (peer_address_.address().empty()) {
1122     peer_address_ = peer_address;
1123   }
1124   if (self_address_.address().empty()) {
1125     self_address_ = self_address;
1126   }
1127
1128   if (!peer_address.address().empty() && !peer_address_.address().empty()) {
1129     peer_ip_changed_ = (peer_address.address() != peer_address_.address());
1130     peer_port_changed_ = (peer_address.port() != peer_address_.port());
1131
1132     // Store in case we want to migrate connection in ProcessValidatedPacket.
1133     migrating_peer_port_ = peer_address.port();
1134   }
1135
1136   if (!self_address.address().empty() && !self_address_.address().empty()) {
1137     self_ip_changed_ = (self_address.address() != self_address_.address());
1138     self_port_changed_ = (self_address.port() != self_address_.port());
1139   }
1140 }
1141
1142 void QuicConnection::OnCanWrite() {
1143   DCHECK(!writer_->IsWriteBlocked());
1144
1145   WriteQueuedPackets();
1146   WritePendingRetransmissions();
1147
1148   // Sending queued packets may have caused the socket to become write blocked,
1149   // or the congestion manager to prohibit sending.  If we've sent everything
1150   // we had queued and we're still not blocked, let the visitor know it can
1151   // write more.
1152   if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1153     return;
1154   }
1155
1156   {  // Limit the scope of the bundler.
1157     // Set |include_ack| to false in bundler; ack inclusion happens elsewhere.
1158     ScopedPacketBundler bundler(this, NO_ACK);
1159     visitor_->OnCanWrite();
1160   }
1161
1162   // After the visitor writes, it may have caused the socket to become write
1163   // blocked or the congestion manager to prohibit sending, so check again.
1164   if (visitor_->WillingAndAbleToWrite() &&
1165       !resume_writes_alarm_->IsSet() &&
1166       CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1167     // We're not write blocked, but some stream didn't write out all of its
1168     // bytes. Register for 'immediate' resumption so we'll keep writing after
1169     // other connections and events have had a chance to use the thread.
1170     resume_writes_alarm_->Set(clock_->ApproximateNow());
1171   }
1172 }
1173
1174 void QuicConnection::WriteIfNotBlocked() {
1175   if (!writer_->IsWriteBlocked()) {
1176     OnCanWrite();
1177   }
1178 }
1179
1180 bool QuicConnection::ProcessValidatedPacket() {
1181   if (peer_ip_changed_ || self_ip_changed_ || self_port_changed_) {
1182     SendConnectionCloseWithDetails(
1183         QUIC_ERROR_MIGRATING_ADDRESS,
1184         "Neither IP address migration, nor self port migration are supported.");
1185     return false;
1186   }
1187
1188   // Peer port migration is supported, do it now if port has changed.
1189   if (peer_port_changed_) {
1190     DVLOG(1) << ENDPOINT << "Peer's port changed from "
1191              << peer_address_.port() << " to " << migrating_peer_port_
1192              << ", migrating connection.";
1193     peer_address_ = IPEndPoint(peer_address_.address(), migrating_peer_port_);
1194   }
1195
1196   time_of_last_received_packet_ = clock_->Now();
1197   DVLOG(1) << ENDPOINT << "time of last received packet: "
1198            << time_of_last_received_packet_.ToDebuggingValue();
1199
1200   if (is_server_ && encryption_level_ == ENCRYPTION_NONE &&
1201       last_size_ > packet_generator_.max_packet_length()) {
1202     packet_generator_.set_max_packet_length(last_size_);
1203   }
1204   return true;
1205 }
1206
1207 void QuicConnection::WriteQueuedPackets() {
1208   DCHECK(!writer_->IsWriteBlocked());
1209
1210   if (pending_version_negotiation_packet_) {
1211     SendVersionNegotiationPacket();
1212   }
1213
1214   QueuedPacketList::iterator packet_iterator = queued_packets_.begin();
1215   while (!writer_->IsWriteBlocked() &&
1216          packet_iterator != queued_packets_.end()) {
1217     if (WritePacket(*packet_iterator)) {
1218       delete packet_iterator->packet;
1219       packet_iterator = queued_packets_.erase(packet_iterator);
1220     } else {
1221       // Continue, because some queued packets may still be writable.
1222       // This can happen if a retransmit send fails.
1223       ++packet_iterator;
1224     }
1225   }
1226 }
1227
1228 void QuicConnection::WritePendingRetransmissions() {
1229   // Keep writing as long as there's a pending retransmission which can be
1230   // written.
1231   while (sent_packet_manager_.HasPendingRetransmissions()) {
1232     const QuicSentPacketManager::PendingRetransmission pending =
1233         sent_packet_manager_.NextPendingRetransmission();
1234     if (GetPacketType(&pending.retransmittable_frames) == NORMAL &&
1235         !CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1236       break;
1237     }
1238
1239     // Re-packetize the frames with a new sequence number for retransmission.
1240     // Retransmitted data packets do not use FEC, even when it's enabled.
1241     // Retransmitted packets use the same sequence number length as the
1242     // original.
1243     // Flush the packet generator before making a new packet.
1244     // TODO(ianswett): Implement ReserializeAllFrames as a separate path that
1245     // does not require the creator to be flushed.
1246     packet_generator_.FlushAllQueuedFrames();
1247     SerializedPacket serialized_packet = packet_generator_.ReserializeAllFrames(
1248         pending.retransmittable_frames.frames(),
1249         pending.sequence_number_length);
1250
1251     DVLOG(1) << ENDPOINT << "Retransmitting " << pending.sequence_number
1252              << " as " << serialized_packet.sequence_number;
1253     if (debug_visitor_.get() != NULL) {
1254       debug_visitor_->OnPacketRetransmitted(
1255           pending.sequence_number, serialized_packet.sequence_number);
1256     }
1257     sent_packet_manager_.OnRetransmittedPacket(
1258         pending.sequence_number,
1259         serialized_packet.sequence_number);
1260
1261     SendOrQueuePacket(pending.retransmittable_frames.encryption_level(),
1262                       serialized_packet,
1263                       pending.transmission_type);
1264   }
1265 }
1266
1267 void QuicConnection::RetransmitUnackedPackets(
1268     RetransmissionType retransmission_type) {
1269   sent_packet_manager_.RetransmitUnackedPackets(retransmission_type);
1270
1271   WriteIfNotBlocked();
1272 }
1273
1274 void QuicConnection::NeuterUnencryptedPackets() {
1275   sent_packet_manager_.NeuterUnencryptedPackets();
1276   // This may have changed the retransmission timer, so re-arm it.
1277   QuicTime retransmission_time = sent_packet_manager_.GetRetransmissionTime();
1278   retransmission_alarm_->Update(retransmission_time,
1279                                 QuicTime::Delta::FromMilliseconds(1));
1280 }
1281
1282 bool QuicConnection::ShouldGeneratePacket(
1283     TransmissionType transmission_type,
1284     HasRetransmittableData retransmittable,
1285     IsHandshake handshake) {
1286   // We should serialize handshake packets immediately to ensure that they
1287   // end up sent at the right encryption level.
1288   if (handshake == IS_HANDSHAKE) {
1289     return true;
1290   }
1291
1292   return CanWrite(retransmittable);
1293 }
1294
1295 bool QuicConnection::CanWrite(HasRetransmittableData retransmittable) {
1296   if (writer_->IsWriteBlocked()) {
1297     visitor_->OnWriteBlocked();
1298     return false;
1299   }
1300
1301   QuicTime now = clock_->Now();
1302   QuicTime::Delta delay = sent_packet_manager_.TimeUntilSend(
1303       now, retransmittable);
1304   if (delay.IsInfinite()) {
1305     send_alarm_->Cancel();
1306     return false;
1307   }
1308
1309   // If the scheduler requires a delay, then we can not send this packet now.
1310   if (!delay.IsZero()) {
1311     send_alarm_->Update(now.Add(delay), QuicTime::Delta::FromMilliseconds(1));
1312     DVLOG(1) << "Delaying sending.";
1313     return false;
1314   }
1315   send_alarm_->Cancel();
1316   return true;
1317 }
1318
1319 bool QuicConnection::WritePacket(QueuedPacket packet) {
1320   QuicPacketSequenceNumber sequence_number = packet.sequence_number;
1321   if (ShouldDiscardPacket(packet.encryption_level,
1322                           sequence_number,
1323                           packet.retransmittable)) {
1324     ++stats_.packets_discarded;
1325     return true;
1326   }
1327
1328   // If the packet is CONNECTION_CLOSE, we need to try to send it immediately
1329   // and encrypt it to hand it off to TimeWaitListManager.
1330   // If the packet is QUEUED, we don't re-consult the congestion control.
1331   // This ensures packets are sent in sequence number order.
1332   // TODO(ianswett): The congestion control should have been consulted before
1333   // serializing the packet, so this could be turned into a LOG_IF(DFATAL).
1334   if (packet.type == NORMAL && !CanWrite(packet.retransmittable)) {
1335     return false;
1336   }
1337
1338   // Some encryption algorithms require the packet sequence numbers not be
1339   // repeated.
1340   DCHECK_LE(sequence_number_of_last_sent_packet_, sequence_number);
1341   sequence_number_of_last_sent_packet_ = sequence_number;
1342
1343   QuicEncryptedPacket* encrypted = framer_.EncryptPacket(
1344       packet.encryption_level, sequence_number, *packet.packet);
1345   if (encrypted == NULL) {
1346     LOG(DFATAL) << ENDPOINT << "Failed to encrypt packet number "
1347                 << sequence_number;
1348     // CloseConnection does not send close packet, so no infinite loop here.
1349     CloseConnection(QUIC_ENCRYPTION_FAILURE, false);
1350     return false;
1351   }
1352
1353   // Connection close packets are eventually owned by TimeWaitListManager.
1354   // Others are deleted at the end of this call.
1355   scoped_ptr<QuicEncryptedPacket> encrypted_deleter;
1356   if (packet.type == CONNECTION_CLOSE) {
1357     DCHECK(connection_close_packet_.get() == NULL);
1358     connection_close_packet_.reset(encrypted);
1359     // This assures we won't try to write *forced* packets when blocked.
1360     // Return true to stop processing.
1361     if (writer_->IsWriteBlocked()) {
1362       visitor_->OnWriteBlocked();
1363       return true;
1364     }
1365   } else {
1366     encrypted_deleter.reset(encrypted);
1367   }
1368
1369   if (!FLAGS_quic_allow_oversized_packets_for_test) {
1370     DCHECK_LE(encrypted->length(), kMaxPacketSize);
1371   }
1372   DCHECK_LE(encrypted->length(), packet_generator_.max_packet_length());
1373   DVLOG(1) << ENDPOINT << "Sending packet " << sequence_number
1374            << " : " << (packet.packet->is_fec_packet() ? "FEC " :
1375                (packet.retransmittable == HAS_RETRANSMITTABLE_DATA
1376                     ? "data bearing " : " ack only "))
1377            << ", encryption level: "
1378            << QuicUtils::EncryptionLevelToString(packet.encryption_level)
1379            << ", length:" << packet.packet->length() << ", encrypted length:"
1380            << encrypted->length();
1381   DVLOG(2) << ENDPOINT << "packet(" << sequence_number << "): " << std::endl
1382            << QuicUtils::StringToHexASCIIDump(packet.packet->AsStringPiece());
1383
1384   WriteResult result = writer_->WritePacket(encrypted->data(),
1385                                             encrypted->length(),
1386                                             self_address().address(),
1387                                             peer_address());
1388   if (result.error_code == ERR_IO_PENDING) {
1389     DCHECK_EQ(WRITE_STATUS_BLOCKED, result.status);
1390   }
1391   if (debug_visitor_.get() != NULL) {
1392     // Pass the write result to the visitor.
1393     debug_visitor_->OnPacketSent(sequence_number,
1394                                  packet.encryption_level,
1395                                  packet.transmission_type,
1396                                  *encrypted,
1397                                  result);
1398   }
1399
1400   if (result.status == WRITE_STATUS_BLOCKED) {
1401     visitor_->OnWriteBlocked();
1402     // If the socket buffers the the data, then the packet should not
1403     // be queued and sent again, which would result in an unnecessary
1404     // duplicate packet being sent.  The helper must call OnCanWrite
1405     // when the write completes, and OnWriteError if an error occurs.
1406     if (!writer_->IsWriteBlockedDataBuffered()) {
1407       return false;
1408     }
1409   }
1410   QuicTime now = clock_->Now();
1411   if (packet.transmission_type == NOT_RETRANSMISSION) {
1412     time_of_last_sent_new_packet_ = now;
1413   }
1414   SetPingAlarm();
1415   DVLOG(1) << ENDPOINT << "time of last sent packet: "
1416            << now.ToDebuggingValue();
1417
1418   // TODO(ianswett): Change the sequence number length and other packet creator
1419   // options by a more explicit API than setting a struct value directly,
1420   // perhaps via the NetworkChangeVisitor.
1421   packet_generator_.UpdateSequenceNumberLength(
1422       sent_packet_manager_.least_packet_awaited_by_peer(),
1423       sent_packet_manager_.GetCongestionWindow());
1424
1425   bool reset_retransmission_alarm =
1426       sent_packet_manager_.OnPacketSent(sequence_number,
1427                                         now,
1428                                         encrypted->length(),
1429                                         packet.transmission_type,
1430                                         packet.retransmittable);
1431
1432   if (reset_retransmission_alarm || !retransmission_alarm_->IsSet()) {
1433     retransmission_alarm_->Update(sent_packet_manager_.GetRetransmissionTime(),
1434                                   QuicTime::Delta::FromMilliseconds(1));
1435   }
1436
1437   stats_.bytes_sent += result.bytes_written;
1438   ++stats_.packets_sent;
1439   if (packet.transmission_type != NOT_RETRANSMISSION) {
1440     stats_.bytes_retransmitted += result.bytes_written;
1441     ++stats_.packets_retransmitted;
1442   }
1443
1444   if (result.status == WRITE_STATUS_ERROR) {
1445     OnWriteError(result.error_code);
1446     return false;
1447   }
1448
1449   return true;
1450 }
1451
1452 bool QuicConnection::ShouldDiscardPacket(
1453     EncryptionLevel level,
1454     QuicPacketSequenceNumber sequence_number,
1455     HasRetransmittableData retransmittable) {
1456   if (!connected_) {
1457     DVLOG(1) << ENDPOINT
1458              << "Not sending packet as connection is disconnected.";
1459     return true;
1460   }
1461
1462   // If the packet has been discarded before sending, don't send it.
1463   // This occurs if a packet gets serialized, queued, then discarded.
1464   if (!sent_packet_manager_.IsUnacked(sequence_number)) {
1465     DVLOG(1) << ENDPOINT << "Dropping packet before sending: "
1466              << sequence_number << " since it has already been discarded.";
1467     return true;
1468   }
1469
1470   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE &&
1471       level == ENCRYPTION_NONE) {
1472     // Drop packets that are NULL encrypted since the peer won't accept them
1473     // anymore.
1474     DVLOG(1) << ENDPOINT << "Dropping NULL encrypted packet: "
1475              << sequence_number << " since the connection is forward secure.";
1476     LOG_IF(DFATAL,
1477            sent_packet_manager_.HasRetransmittableFrames(sequence_number))
1478         << "Once forward secure, all NULL encrypted packets should be "
1479         << "neutered.";
1480     return true;
1481   }
1482
1483   if (retransmittable == HAS_RETRANSMITTABLE_DATA &&
1484       !sent_packet_manager_.HasRetransmittableFrames(sequence_number)) {
1485     DVLOG(1) << ENDPOINT << "Dropping unacked packet: " << sequence_number
1486              << " A previous transmission was acked while write blocked.";
1487     return true;
1488   }
1489
1490   return false;
1491 }
1492
1493 void QuicConnection::OnWriteError(int error_code) {
1494   DVLOG(1) << ENDPOINT << "Write failed with error: " << error_code
1495            << " (" << ErrorToString(error_code) << ")";
1496   // We can't send an error as the socket is presumably borked.
1497   CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
1498 }
1499
1500 bool QuicConnection::OnSerializedPacket(
1501     const SerializedPacket& serialized_packet) {
1502   if (serialized_packet.retransmittable_frames) {
1503     serialized_packet.retransmittable_frames->
1504         set_encryption_level(encryption_level_);
1505   }
1506   sent_packet_manager_.OnSerializedPacket(serialized_packet);
1507   // The TransmissionType is NOT_RETRANSMISSION because all retransmissions
1508   // serialize packets and invoke SendOrQueuePacket directly.
1509   return SendOrQueuePacket(encryption_level_,
1510                            serialized_packet,
1511                            NOT_RETRANSMISSION);
1512 }
1513
1514 void QuicConnection::OnCongestionWindowChange(QuicByteCount congestion_window) {
1515   packet_generator_.OnCongestionWindowChange(congestion_window);
1516   visitor_->OnCongestionWindowChange(clock_->ApproximateNow());
1517 }
1518
1519 void QuicConnection::OnHandshakeComplete() {
1520   sent_packet_manager_.SetHandshakeConfirmed();
1521 }
1522
1523 bool QuicConnection::SendOrQueuePacket(EncryptionLevel level,
1524                                        const SerializedPacket& packet,
1525                                        TransmissionType transmission_type) {
1526   if (packet.packet == NULL) {
1527     LOG(DFATAL) << "NULL packet passed in to SendOrQueuePacket";
1528     return true;
1529   }
1530
1531   sent_entropy_manager_.RecordPacketEntropyHash(packet.sequence_number,
1532                                                 packet.entropy_hash);
1533   QueuedPacket queued_packet(packet, level, transmission_type);
1534   // If there are already queued packets, put this at the end,
1535   // unless it's ConnectionClose, in which case it is written immediately.
1536   if ((queued_packet.type == CONNECTION_CLOSE || queued_packets_.empty()) &&
1537       WritePacket(queued_packet)) {
1538     delete packet.packet;
1539     return true;
1540   }
1541   queued_packet.type = QUEUED;
1542   queued_packets_.push_back(queued_packet);
1543   return false;
1544 }
1545
1546 void QuicConnection::UpdateStopWaiting(QuicStopWaitingFrame* stop_waiting) {
1547   stop_waiting->least_unacked = GetLeastUnacked();
1548   stop_waiting->entropy_hash = sent_entropy_manager_.GetCumulativeEntropy(
1549       stop_waiting->least_unacked - 1);
1550 }
1551
1552 void QuicConnection::SendPing() {
1553   if (retransmission_alarm_->IsSet()) {
1554     return;
1555   }
1556   if (version() == QUIC_VERSION_16) {
1557     // TODO(rch): remove this when we remove version 15 and 16.
1558     // This is a horrible hideous hack which we should not support.
1559     IOVector data;
1560     char c_data[] = "C";
1561     data.Append(c_data, 1);
1562     QuicConsumedData consumed_data =
1563         packet_generator_.ConsumeData(kCryptoStreamId, data, 0, false,
1564                                       MAY_FEC_PROTECT, NULL);
1565     if (consumed_data.bytes_consumed == 0) {
1566       DLOG(ERROR) << "Unable to send ping!?";
1567     }
1568   } else {
1569     packet_generator_.AddControlFrame(QuicFrame(new QuicPingFrame));
1570   }
1571 }
1572
1573 void QuicConnection::SendAck() {
1574   ack_alarm_->Cancel();
1575   stop_waiting_count_ = 0;
1576   bool send_feedback = false;
1577
1578   // Deprecating the Congestion Feedback Frame after QUIC_VERSION_22.
1579   if (version() <= QUIC_VERSION_22) {
1580     if (received_packet_manager_.GenerateCongestionFeedback(
1581             &outgoing_congestion_feedback_)) {
1582       DVLOG(1) << ENDPOINT << "Sending feedback: "
1583                << outgoing_congestion_feedback_;
1584       send_feedback = true;
1585     }
1586   }
1587
1588   packet_generator_.SetShouldSendAck(send_feedback, true);
1589 }
1590
1591 void QuicConnection::OnRetransmissionTimeout() {
1592   if (!sent_packet_manager_.HasUnackedPackets()) {
1593     return;
1594   }
1595
1596   sent_packet_manager_.OnRetransmissionTimeout();
1597   WriteIfNotBlocked();
1598
1599   // A write failure can result in the connection being closed, don't attempt to
1600   // write further packets, or to set alarms.
1601   if (!connected_) {
1602     return;
1603   }
1604
1605   // In the TLP case, the SentPacketManager gives the connection the opportunity
1606   // to send new data before retransmitting.
1607   if (sent_packet_manager_.MaybeRetransmitTailLossProbe()) {
1608     // Send the pending retransmission now that it's been queued.
1609     WriteIfNotBlocked();
1610   }
1611
1612   // Ensure the retransmission alarm is always set if there are unacked packets
1613   // and nothing waiting to be sent.
1614   if (!HasQueuedData() && !retransmission_alarm_->IsSet()) {
1615     QuicTime rto_timeout = sent_packet_manager_.GetRetransmissionTime();
1616     if (rto_timeout.IsInitialized()) {
1617       retransmission_alarm_->Set(rto_timeout);
1618     }
1619   }
1620 }
1621
1622 void QuicConnection::SetEncrypter(EncryptionLevel level,
1623                                   QuicEncrypter* encrypter) {
1624   framer_.SetEncrypter(level, encrypter);
1625 }
1626
1627 const QuicEncrypter* QuicConnection::encrypter(EncryptionLevel level) const {
1628   return framer_.encrypter(level);
1629 }
1630
1631 void QuicConnection::SetDefaultEncryptionLevel(EncryptionLevel level) {
1632   encryption_level_ = level;
1633   packet_generator_.set_encryption_level(level);
1634 }
1635
1636 void QuicConnection::SetDecrypter(QuicDecrypter* decrypter,
1637                                   EncryptionLevel level) {
1638   framer_.SetDecrypter(decrypter, level);
1639 }
1640
1641 void QuicConnection::SetAlternativeDecrypter(QuicDecrypter* decrypter,
1642                                              EncryptionLevel level,
1643                                              bool latch_once_used) {
1644   framer_.SetAlternativeDecrypter(decrypter, level, latch_once_used);
1645 }
1646
1647 const QuicDecrypter* QuicConnection::decrypter() const {
1648   return framer_.decrypter();
1649 }
1650
1651 const QuicDecrypter* QuicConnection::alternative_decrypter() const {
1652   return framer_.alternative_decrypter();
1653 }
1654
1655 void QuicConnection::QueueUndecryptablePacket(
1656     const QuicEncryptedPacket& packet) {
1657   DVLOG(1) << ENDPOINT << "Queueing undecryptable packet.";
1658   undecryptable_packets_.push_back(packet.Clone());
1659 }
1660
1661 void QuicConnection::MaybeProcessUndecryptablePackets() {
1662   if (undecryptable_packets_.empty() || encryption_level_ == ENCRYPTION_NONE) {
1663     return;
1664   }
1665
1666   while (connected_ && !undecryptable_packets_.empty()) {
1667     DVLOG(1) << ENDPOINT << "Attempting to process undecryptable packet";
1668     QuicEncryptedPacket* packet = undecryptable_packets_.front();
1669     if (!framer_.ProcessPacket(*packet) &&
1670         framer_.error() == QUIC_DECRYPTION_FAILURE) {
1671       DVLOG(1) << ENDPOINT << "Unable to process undecryptable packet...";
1672       break;
1673     }
1674     DVLOG(1) << ENDPOINT << "Processed undecryptable packet!";
1675     ++stats_.packets_processed;
1676     delete packet;
1677     undecryptable_packets_.pop_front();
1678   }
1679
1680   // Once forward secure encryption is in use, there will be no
1681   // new keys installed and hence any undecryptable packets will
1682   // never be able to be decrypted.
1683   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE) {
1684     if (debug_visitor_.get() != NULL) {
1685       // TODO(rtenneti): perhaps more efficient to pass the number of
1686       // undecryptable packets as the argument to OnUndecryptablePacket so that
1687       // we just need to call OnUndecryptablePacket once?
1688       for (size_t i = 0; i < undecryptable_packets_.size(); ++i) {
1689         debug_visitor_->OnUndecryptablePacket();
1690       }
1691     }
1692     STLDeleteElements(&undecryptable_packets_);
1693   }
1694 }
1695
1696 void QuicConnection::MaybeProcessRevivedPacket() {
1697   QuicFecGroup* group = GetFecGroup();
1698   if (!connected_ || group == NULL || !group->CanRevive()) {
1699     return;
1700   }
1701   QuicPacketHeader revived_header;
1702   char revived_payload[kMaxPacketSize];
1703   size_t len = group->Revive(&revived_header, revived_payload, kMaxPacketSize);
1704   revived_header.public_header.connection_id = connection_id_;
1705   revived_header.public_header.connection_id_length =
1706       last_header_.public_header.connection_id_length;
1707   revived_header.public_header.version_flag = false;
1708   revived_header.public_header.reset_flag = false;
1709   revived_header.public_header.sequence_number_length =
1710       last_header_.public_header.sequence_number_length;
1711   revived_header.fec_flag = false;
1712   revived_header.is_in_fec_group = NOT_IN_FEC_GROUP;
1713   revived_header.fec_group = 0;
1714   group_map_.erase(last_header_.fec_group);
1715   last_decrypted_packet_level_ = group->effective_encryption_level();
1716   DCHECK_LT(last_decrypted_packet_level_, NUM_ENCRYPTION_LEVELS);
1717   delete group;
1718
1719   last_packet_revived_ = true;
1720   if (debug_visitor_.get() != NULL) {
1721     debug_visitor_->OnRevivedPacket(revived_header,
1722                                     StringPiece(revived_payload, len));
1723   }
1724
1725   ++stats_.packets_revived;
1726   framer_.ProcessRevivedPacket(&revived_header,
1727                                StringPiece(revived_payload, len));
1728 }
1729
1730 QuicFecGroup* QuicConnection::GetFecGroup() {
1731   QuicFecGroupNumber fec_group_num = last_header_.fec_group;
1732   if (fec_group_num == 0) {
1733     return NULL;
1734   }
1735   if (group_map_.count(fec_group_num) == 0) {
1736     if (group_map_.size() >= kMaxFecGroups) {  // Too many groups
1737       if (fec_group_num < group_map_.begin()->first) {
1738         // The group being requested is a group we've seen before and deleted.
1739         // Don't recreate it.
1740         return NULL;
1741       }
1742       // Clear the lowest group number.
1743       delete group_map_.begin()->second;
1744       group_map_.erase(group_map_.begin());
1745     }
1746     group_map_[fec_group_num] = new QuicFecGroup();
1747   }
1748   return group_map_[fec_group_num];
1749 }
1750
1751 void QuicConnection::SendConnectionClose(QuicErrorCode error) {
1752   SendConnectionCloseWithDetails(error, string());
1753 }
1754
1755 void QuicConnection::SendConnectionCloseWithDetails(QuicErrorCode error,
1756                                                     const string& details) {
1757   // If we're write blocked, WritePacket() will not send, but will capture the
1758   // serialized packet.
1759   SendConnectionClosePacket(error, details);
1760   if (connected_) {
1761     // It's possible that while sending the connection close packet, we get a
1762     // socket error and disconnect right then and there.  Avoid a double
1763     // disconnect in that case.
1764     CloseConnection(error, false);
1765   }
1766 }
1767
1768 void QuicConnection::SendConnectionClosePacket(QuicErrorCode error,
1769                                                const string& details) {
1770   DVLOG(1) << ENDPOINT << "Force closing " << connection_id()
1771            << " with error " << QuicUtils::ErrorToString(error)
1772            << " (" << error << ") " << details;
1773   ScopedPacketBundler ack_bundler(this, SEND_ACK);
1774   QuicConnectionCloseFrame* frame = new QuicConnectionCloseFrame();
1775   frame->error_code = error;
1776   frame->error_details = details;
1777   packet_generator_.AddControlFrame(QuicFrame(frame));
1778   packet_generator_.FlushAllQueuedFrames();
1779 }
1780
1781 void QuicConnection::CloseConnection(QuicErrorCode error, bool from_peer) {
1782   if (!connected_) {
1783     DLOG(DFATAL) << "Error: attempt to close an already closed connection"
1784                  << base::debug::StackTrace().ToString();
1785     return;
1786   }
1787   connected_ = false;
1788   if (debug_visitor_.get() != NULL) {
1789     debug_visitor_->OnConnectionClosed(error, from_peer);
1790   }
1791   visitor_->OnConnectionClosed(error, from_peer);
1792   // Cancel the alarms so they don't trigger any action now that the
1793   // connection is closed.
1794   ack_alarm_->Cancel();
1795   ping_alarm_->Cancel();
1796   resume_writes_alarm_->Cancel();
1797   retransmission_alarm_->Cancel();
1798   send_alarm_->Cancel();
1799   timeout_alarm_->Cancel();
1800 }
1801
1802 void QuicConnection::SendGoAway(QuicErrorCode error,
1803                                 QuicStreamId last_good_stream_id,
1804                                 const string& reason) {
1805   DVLOG(1) << ENDPOINT << "Going away with error "
1806            << QuicUtils::ErrorToString(error)
1807            << " (" << error << ")";
1808
1809   // Opportunistically bundle an ack with this outgoing packet.
1810   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1811   packet_generator_.AddControlFrame(
1812       QuicFrame(new QuicGoAwayFrame(error, last_good_stream_id, reason)));
1813 }
1814
1815 void QuicConnection::CloseFecGroupsBefore(
1816     QuicPacketSequenceNumber sequence_number) {
1817   FecGroupMap::iterator it = group_map_.begin();
1818   while (it != group_map_.end()) {
1819     // If this is the current group or the group doesn't protect this packet
1820     // we can ignore it.
1821     if (last_header_.fec_group == it->first ||
1822         !it->second->ProtectsPacketsBefore(sequence_number)) {
1823       ++it;
1824       continue;
1825     }
1826     QuicFecGroup* fec_group = it->second;
1827     DCHECK(!fec_group->CanRevive());
1828     FecGroupMap::iterator next = it;
1829     ++next;
1830     group_map_.erase(it);
1831     delete fec_group;
1832     it = next;
1833   }
1834 }
1835
1836 size_t QuicConnection::max_packet_length() const {
1837   return packet_generator_.max_packet_length();
1838 }
1839
1840 void QuicConnection::set_max_packet_length(size_t length) {
1841   return packet_generator_.set_max_packet_length(length);
1842 }
1843
1844 bool QuicConnection::HasQueuedData() const {
1845   return pending_version_negotiation_packet_ ||
1846       !queued_packets_.empty() || packet_generator_.HasQueuedFrames();
1847 }
1848
1849 bool QuicConnection::CanWriteStreamData() {
1850   // Don't write stream data if there are negotiation or queued data packets
1851   // to send. Otherwise, continue and bundle as many frames as possible.
1852   if (pending_version_negotiation_packet_ || !queued_packets_.empty()) {
1853     return false;
1854   }
1855
1856   IsHandshake pending_handshake = visitor_->HasPendingHandshake() ?
1857       IS_HANDSHAKE : NOT_HANDSHAKE;
1858   // Sending queued packets may have caused the socket to become write blocked,
1859   // or the congestion manager to prohibit sending.  If we've sent everything
1860   // we had queued and we're still not blocked, let the visitor know it can
1861   // write more.
1862   return ShouldGeneratePacket(NOT_RETRANSMISSION, HAS_RETRANSMITTABLE_DATA,
1863                               pending_handshake);
1864 }
1865
1866 void QuicConnection::SetIdleNetworkTimeout(QuicTime::Delta timeout) {
1867   // Adjust the idle timeout on client and server to prevent clients from
1868   // sending requests to servers which have already closed the connection.
1869   if (is_server_) {
1870     timeout = timeout.Add(QuicTime::Delta::FromSeconds(1));
1871   } else if (timeout > QuicTime::Delta::FromSeconds(1)) {
1872     timeout = timeout.Subtract(QuicTime::Delta::FromSeconds(1));
1873   }
1874
1875   if (timeout < idle_network_timeout_) {
1876     idle_network_timeout_ = timeout;
1877     CheckForTimeout();
1878   } else {
1879     idle_network_timeout_ = timeout;
1880   }
1881 }
1882
1883 void QuicConnection::SetOverallConnectionTimeout(QuicTime::Delta timeout) {
1884   if (timeout < overall_connection_timeout_) {
1885     overall_connection_timeout_ = timeout;
1886     CheckForTimeout();
1887   } else {
1888     overall_connection_timeout_ = timeout;
1889   }
1890 }
1891
1892 bool QuicConnection::CheckForTimeout() {
1893   QuicTime now = clock_->ApproximateNow();
1894   QuicTime time_of_last_packet = max(time_of_last_received_packet_,
1895                                      time_of_last_sent_new_packet_);
1896
1897   // |delta| can be < 0 as |now| is approximate time but |time_of_last_packet|
1898   // is accurate time. However, this should not change the behavior of
1899   // timeout handling.
1900   QuicTime::Delta delta = now.Subtract(time_of_last_packet);
1901   DVLOG(1) << ENDPOINT << "last packet "
1902            << time_of_last_packet.ToDebuggingValue()
1903            << " now:" << now.ToDebuggingValue()
1904            << " delta:" << delta.ToMicroseconds()
1905            << " network_timeout: " << idle_network_timeout_.ToMicroseconds();
1906   if (delta >= idle_network_timeout_) {
1907     DVLOG(1) << ENDPOINT << "Connection timedout due to no network activity.";
1908     SendConnectionClose(QUIC_CONNECTION_TIMED_OUT);
1909     return true;
1910   }
1911
1912   // Next timeout delta.
1913   QuicTime::Delta timeout = idle_network_timeout_.Subtract(delta);
1914
1915   if (!overall_connection_timeout_.IsInfinite()) {
1916     QuicTime::Delta connected_time =
1917         now.Subtract(stats_.connection_creation_time);
1918     DVLOG(1) << ENDPOINT << "connection time: "
1919              << connected_time.ToMilliseconds() << " overall timeout: "
1920              << overall_connection_timeout_.ToMilliseconds();
1921     if (connected_time >= overall_connection_timeout_) {
1922       DVLOG(1) << ENDPOINT <<
1923           "Connection timedout due to overall connection timeout.";
1924       SendConnectionClose(QUIC_CONNECTION_TIMED_OUT);
1925       return true;
1926     }
1927
1928     // Take the min timeout.
1929     QuicTime::Delta connection_timeout =
1930         overall_connection_timeout_.Subtract(connected_time);
1931     if (connection_timeout < timeout) {
1932       timeout = connection_timeout;
1933     }
1934   }
1935
1936   timeout_alarm_->Cancel();
1937   timeout_alarm_->Set(now.Add(timeout));
1938   return false;
1939 }
1940
1941 void QuicConnection::SetPingAlarm() {
1942   if (is_server_) {
1943     // Only clients send pings.
1944     return;
1945   }
1946   if (!visitor_->HasOpenDataStreams()) {
1947     ping_alarm_->Cancel();
1948     // Don't send a ping unless there are open streams.
1949     return;
1950   }
1951   QuicTime::Delta ping_timeout = QuicTime::Delta::FromSeconds(kPingTimeoutSecs);
1952   ping_alarm_->Update(clock_->ApproximateNow().Add(ping_timeout),
1953                       QuicTime::Delta::FromSeconds(1));
1954 }
1955
1956 QuicConnection::ScopedPacketBundler::ScopedPacketBundler(
1957     QuicConnection* connection,
1958     AckBundling send_ack)
1959     : connection_(connection),
1960       already_in_batch_mode_(connection != NULL &&
1961                              connection->packet_generator_.InBatchMode()) {
1962   if (connection_  == NULL) {
1963     return;
1964   }
1965   // Move generator into batch mode. If caller wants us to include an ack,
1966   // check the delayed-ack timer to see if there's ack info to be sent.
1967   if (!already_in_batch_mode_) {
1968     DVLOG(1) << "Entering Batch Mode.";
1969     connection_->packet_generator_.StartBatchOperations();
1970   }
1971   // Bundle an ack if the alarm is set or with every second packet if we need to
1972   // raise the peer's least unacked.
1973   bool ack_pending =
1974       connection_->ack_alarm_->IsSet() || connection_->stop_waiting_count_ > 1;
1975   if (send_ack == SEND_ACK || (send_ack == BUNDLE_PENDING_ACK && ack_pending)) {
1976     DVLOG(1) << "Bundling ack with outgoing packet.";
1977     connection_->SendAck();
1978   }
1979 }
1980
1981 QuicConnection::ScopedPacketBundler::~ScopedPacketBundler() {
1982   if (connection_  == NULL) {
1983     return;
1984   }
1985   // If we changed the generator's batch state, restore original batch state.
1986   if (!already_in_batch_mode_) {
1987     DVLOG(1) << "Leaving Batch Mode.";
1988     connection_->packet_generator_.FinishBatchOperations();
1989   }
1990   DCHECK_EQ(already_in_batch_mode_,
1991             connection_->packet_generator_.InBatchMode());
1992 }
1993
1994 }  // namespace net