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_fec_group.h"
  26 #include "net/quic/quic_flags.h"
  27 #include "net/quic/quic_utils.h"
  28
  29 using base::StringPiece;
  30 using base::hash_map;
  31 using base::hash_set;
  32 using std::list;
  33 using std::make_pair;
  34 using std::max;
  35 using std::min;
  36 using std::numeric_limits;
  37 using std::set;
  38 using std::string;
  39 using std::vector;
  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 // Maximum number of acks received before sending an ack in response.
  61 const size_t kMaxPacketsReceivedBeforeAckSend = 20;
  62
  63 bool Near(QuicPacketSequenceNumber a, QuicPacketSequenceNumber b) {
  64   QuicPacketSequenceNumber delta = (a > b) ? a - b : b - a;
  65   return delta <= kMaxPacketGap;
  66 }
  67
  68 // An alarm that is scheduled to send an ack if a timeout occurs.
  69 class AckAlarm : public QuicAlarm::Delegate {
  70  public:
  71   explicit AckAlarm(QuicConnection* connection)
  72       : connection_(connection) {
  73   }
  74
  75   virtual QuicTime OnAlarm() OVERRIDE {
  76     connection_->SendAck();
  77     return QuicTime::Zero();
  78   }
  79
  80  private:
  81   QuicConnection* connection_;
  82
  83   DISALLOW_COPY_AND_ASSIGN(AckAlarm);
  84 };
  85
  86 // This alarm will be scheduled any time a data-bearing packet is sent out.
  87 // When the alarm goes off, the connection checks to see if the oldest packets
  88 // have been acked, and retransmit them if they have not.
  89 class RetransmissionAlarm : public QuicAlarm::Delegate {
  90  public:
  91   explicit RetransmissionAlarm(QuicConnection* connection)
  92       : connection_(connection) {
  93   }
  94
  95   virtual QuicTime OnAlarm() OVERRIDE {
  96     connection_->OnRetransmissionTimeout();
  97     return QuicTime::Zero();
  98   }
  99
 100  private:
 101   QuicConnection* connection_;
 102
 103   DISALLOW_COPY_AND_ASSIGN(RetransmissionAlarm);
 104 };
 105
 106 // An alarm that is scheduled when the sent scheduler requires a
 107 // a delay before sending packets and fires when the packet may be sent.
 108 class SendAlarm : public QuicAlarm::Delegate {
 109  public:
 110   explicit SendAlarm(QuicConnection* connection)
 111       : connection_(connection) {
 112   }
 113
 114   virtual QuicTime OnAlarm() OVERRIDE {
 115     connection_->WriteIfNotBlocked();
 116     // Never reschedule the alarm, since CanWrite does that.
 117     return QuicTime::Zero();
 118   }
 119
 120  private:
 121   QuicConnection* connection_;
 122
 123   DISALLOW_COPY_AND_ASSIGN(SendAlarm);
 124 };
 125
 126 class TimeoutAlarm : public QuicAlarm::Delegate {
 127  public:
 128   explicit TimeoutAlarm(QuicConnection* connection)
 129       : connection_(connection) {
 130   }
 131
 132   virtual QuicTime OnAlarm() OVERRIDE {
 133     connection_->CheckForTimeout();
 134     // Never reschedule the alarm, since CheckForTimeout does that.
 135     return QuicTime::Zero();
 136   }
 137
 138  private:
 139   QuicConnection* connection_;
 140
 141   DISALLOW_COPY_AND_ASSIGN(TimeoutAlarm);
 142 };
 143
 144 class PingAlarm : public QuicAlarm::Delegate {
 145  public:
 146   explicit PingAlarm(QuicConnection* connection)
 147       : connection_(connection) {
 148   }
 149
 150   virtual QuicTime OnAlarm() OVERRIDE {
 151     connection_->SendPing();
 152     return QuicTime::Zero();
 153   }
 154
 155  private:
 156   QuicConnection* connection_;
 157
 158   DISALLOW_COPY_AND_ASSIGN(PingAlarm);
 159 };
 160
 161 }  // namespace
 162
 163 QuicConnection::QueuedPacket::QueuedPacket(SerializedPacket packet,
 164                                            EncryptionLevel level)
 165   : serialized_packet(packet),
 166     encryption_level(level),
 167     transmission_type(NOT_RETRANSMISSION),
 168     original_sequence_number(0) {
 169 }
 170
 171 QuicConnection::QueuedPacket::QueuedPacket(
 172     SerializedPacket packet,
 173     EncryptionLevel level,
 174     TransmissionType transmission_type,
 175     QuicPacketSequenceNumber original_sequence_number)
 176     : serialized_packet(packet),
 177       encryption_level(level),
 178       transmission_type(transmission_type),
 179       original_sequence_number(original_sequence_number) {
 180 }
 181
 182 #define ENDPOINT (is_server_ ? "Server: " : " Client: ")
 183
 184 QuicConnection::QuicConnection(QuicConnectionId connection_id,
 185                                IPEndPoint address,
 186                                QuicConnectionHelperInterface* helper,
 187                                const PacketWriterFactory& writer_factory,
 188                                bool owns_writer,
 189                                bool is_server,
 190                                const QuicVersionVector& supported_versions)
 191     : framer_(supported_versions, helper->GetClock()->ApproximateNow(),
 192               is_server),
 193       helper_(helper),
 194       writer_(writer_factory.Create(this)),
 195       owns_writer_(owns_writer),
 196       encryption_level_(ENCRYPTION_NONE),
 197       clock_(helper->GetClock()),
 198       random_generator_(helper->GetRandomGenerator()),
 199       connection_id_(connection_id),
 200       peer_address_(address),
 201       migrating_peer_port_(0),
 202       last_packet_revived_(false),
 203       last_size_(0),
 204       last_decrypted_packet_level_(ENCRYPTION_NONE),
 205       largest_seen_packet_with_ack_(0),
 206       largest_seen_packet_with_stop_waiting_(0),
 207       pending_version_negotiation_packet_(false),
 208       received_packet_manager_(&stats_),
 209       ack_queued_(false),
 210       num_packets_received_since_last_ack_sent_(0),
 211       stop_waiting_count_(0),
 212       ack_alarm_(helper->CreateAlarm(new AckAlarm(this))),
 213       retransmission_alarm_(helper->CreateAlarm(new RetransmissionAlarm(this))),
 214       send_alarm_(helper->CreateAlarm(new SendAlarm(this))),
 215       resume_writes_alarm_(helper->CreateAlarm(new SendAlarm(this))),
 216       timeout_alarm_(helper->CreateAlarm(new TimeoutAlarm(this))),
 217       ping_alarm_(helper->CreateAlarm(new PingAlarm(this))),
 218       packet_generator_(connection_id_, &framer_, random_generator_, this),
 219       idle_network_timeout_(
 220           QuicTime::Delta::FromSeconds(kDefaultInitialTimeoutSecs)),
 221       overall_connection_timeout_(QuicTime::Delta::Infinite()),
 222       time_of_last_received_packet_(
 223           FLAGS_quic_timeouts_require_activity
 224               ? QuicTime::Zero() : clock_->ApproximateNow()),
 225       time_of_last_sent_new_packet_(
 226           FLAGS_quic_timeouts_require_activity
 227               ? QuicTime::Zero() : clock_->ApproximateNow()),
 228       sequence_number_of_last_sent_packet_(0),
 229       sent_packet_manager_(
 230           is_server, clock_, &stats_,
 231           FLAGS_quic_use_bbr_congestion_control ? kBBR : kCubic,
 232           FLAGS_quic_use_time_loss_detection ? kTime : kNack),
 233       version_negotiation_state_(START_NEGOTIATION),
 234       is_server_(is_server),
 235       connected_(true),
 236       peer_ip_changed_(false),
 237       peer_port_changed_(false),
 238       self_ip_changed_(false),
 239       self_port_changed_(false) {
 240 #if 0
 241   // TODO(rtenneti): Should we enable this code in chromium?
 242   if (!is_server_) {
 243     // Pacing will be enabled if the client negotiates it.
 244     sent_packet_manager_.MaybeEnablePacing();
 245   }
 246 #endif
 247   DVLOG(1) << ENDPOINT << "Created connection with connection_id: "
 248            << connection_id;
 249   timeout_alarm_->Set(clock_->ApproximateNow().Add(idle_network_timeout_));
 250   framer_.set_visitor(this);
 251   framer_.set_received_entropy_calculator(&received_packet_manager_);
 252   stats_.connection_creation_time = clock_->ApproximateNow();
 253   sent_packet_manager_.set_network_change_visitor(this);
 254 }
 255
 256 QuicConnection::~QuicConnection() {
 257   if (owns_writer_) {
 258     delete writer_;
 259   }
 260   STLDeleteElements(&undecryptable_packets_);
 261   STLDeleteValues(&group_map_);
 262   for (QueuedPacketList::iterator it = queued_packets_.begin();
 263        it != queued_packets_.end(); ++it) {
 264     delete it->serialized_packet.retransmittable_frames;
 265     delete it->serialized_packet.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_ack_frames_.empty() &&
 304          last_congestion_frames_.empty() &&
 305          last_stop_waiting_frames_.empty() &&
 306          last_rst_frames_.empty() &&
 307          last_goaway_frames_.empty() &&
 308          last_window_update_frames_.empty() &&
 309          last_blocked_frames_.empty() &&
 310          last_ping_frames_.empty() &&
 311          last_close_frames_.empty());
 312 }
 313
 314 void QuicConnection::OnPublicResetPacket(
 315     const QuicPublicResetPacket& packet) {
 316   if (debug_visitor_.get() != NULL) {
 317     debug_visitor_->OnPublicResetPacket(packet);
 318   }
 319   CloseConnection(QUIC_PUBLIC_RESET, true);
 320
 321   DVLOG(1) << ENDPOINT << "Connection " << connection_id()
 322            << " closed via QUIC_PUBLIC_RESET from peer.";
 323 }
 324
 325 bool QuicConnection::OnProtocolVersionMismatch(QuicVersion received_version) {
 326   DVLOG(1) << ENDPOINT << "Received packet with mismatched version "
 327            << received_version;
 328   // TODO(satyamshekhar): Implement no server state in this mode.
 329   if (!is_server_) {
 330     LOG(DFATAL) << ENDPOINT << "Framer called OnProtocolVersionMismatch. "
 331                 << "Closing connection.";
 332     CloseConnection(QUIC_INTERNAL_ERROR, false);
 333     return false;
 334   }
 335   DCHECK_NE(version(), received_version);
 336
 337   if (debug_visitor_.get() != NULL) {
 338     debug_visitor_->OnProtocolVersionMismatch(received_version);
 339   }
 340
 341   switch (version_negotiation_state_) {
 342     case START_NEGOTIATION:
 343       if (!framer_.IsSupportedVersion(received_version)) {
 344         SendVersionNegotiationPacket();
 345         version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
 346         return false;
 347       }
 348       break;
 349
 350     case NEGOTIATION_IN_PROGRESS:
 351       if (!framer_.IsSupportedVersion(received_version)) {
 352         SendVersionNegotiationPacket();
 353         return false;
 354       }
 355       break;
 356
 357     case NEGOTIATED_VERSION:
 358       // Might be old packets that were sent by the client before the version
 359       // was negotiated. Drop these.
 360       return false;
 361
 362     default:
 363       DCHECK(false);
 364   }
 365
 366   version_negotiation_state_ = NEGOTIATED_VERSION;
 367   visitor_->OnSuccessfulVersionNegotiation(received_version);
 368   if (debug_visitor_.get() != NULL) {
 369     debug_visitor_->OnSuccessfulVersionNegotiation(received_version);
 370   }
 371   DVLOG(1) << ENDPOINT << "version negotiated " << received_version;
 372
 373   // Store the new version.
 374   framer_.set_version(received_version);
 375
 376   // TODO(satyamshekhar): Store the sequence number of this packet and close the
 377   // connection if we ever received a packet with incorrect version and whose
 378   // sequence number is greater.
 379   return true;
 380 }
 381
 382 // Handles version negotiation for client connection.
 383 void QuicConnection::OnVersionNegotiationPacket(
 384     const QuicVersionNegotiationPacket& packet) {
 385   if (is_server_) {
 386     LOG(DFATAL) << ENDPOINT << "Framer parsed VersionNegotiationPacket."
 387                 << " Closing connection.";
 388     CloseConnection(QUIC_INTERNAL_ERROR, false);
 389     return;
 390   }
 391   if (debug_visitor_.get() != NULL) {
 392     debug_visitor_->OnVersionNegotiationPacket(packet);
 393   }
 394
 395   if (version_negotiation_state_ != START_NEGOTIATION) {
 396     // Possibly a duplicate version negotiation packet.
 397     return;
 398   }
 399
 400   if (std::find(packet.versions.begin(),
 401                 packet.versions.end(), version()) !=
 402       packet.versions.end()) {
 403     DLOG(WARNING) << ENDPOINT << "The server already supports our version. "
 404                   << "It should have accepted our connection.";
 405     // Just drop the connection.
 406     CloseConnection(QUIC_INVALID_VERSION_NEGOTIATION_PACKET, false);
 407     return;
 408   }
 409
 410   if (!SelectMutualVersion(packet.versions)) {
 411     SendConnectionCloseWithDetails(QUIC_INVALID_VERSION,
 412                                    "no common version found");
 413     return;
 414   }
 415
 416   DVLOG(1) << ENDPOINT
 417            << "Negotiated version: " << QuicVersionToString(version());
 418   server_supported_versions_ = packet.versions;
 419   version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
 420   RetransmitUnackedPackets(ALL_UNACKED_RETRANSMISSION);
 421 }
 422
 423 void QuicConnection::OnRevivedPacket() {
 424 }
 425
 426 bool QuicConnection::OnUnauthenticatedPublicHeader(
 427     const QuicPacketPublicHeader& header) {
 428   return true;
 429 }
 430
 431 bool QuicConnection::OnUnauthenticatedHeader(const QuicPacketHeader& header) {
 432   return true;
 433 }
 434
 435 void QuicConnection::OnDecryptedPacket(EncryptionLevel level) {
 436   last_decrypted_packet_level_ = level;
 437 }
 438
 439 bool QuicConnection::OnPacketHeader(const QuicPacketHeader& header) {
 440   if (debug_visitor_.get() != NULL) {
 441     debug_visitor_->OnPacketHeader(header);
 442   }
 443
 444   if (!ProcessValidatedPacket()) {
 445     return false;
 446   }
 447
 448   // Will be decrement below if we fall through to return true;
 449   ++stats_.packets_dropped;
 450
 451   if (header.public_header.connection_id != connection_id_) {
 452     DVLOG(1) << ENDPOINT << "Ignoring packet from unexpected ConnectionId: "
 453              << header.public_header.connection_id << " instead of "
 454              << connection_id_;
 455     if (debug_visitor_.get() != NULL) {
 456       debug_visitor_->OnIncorrectConnectionId(
 457           header.public_header.connection_id);
 458     }
 459     return false;
 460   }
 461
 462   if (!Near(header.packet_sequence_number,
 463             last_header_.packet_sequence_number)) {
 464     DVLOG(1) << ENDPOINT << "Packet " << header.packet_sequence_number
 465              << " out of bounds.  Discarding";
 466     SendConnectionCloseWithDetails(QUIC_INVALID_PACKET_HEADER,
 467                                    "Packet sequence number out of bounds");
 468     return false;
 469   }
 470
 471   // If this packet has already been seen, or that the sender
 472   // has told us will not be retransmitted, then stop processing the packet.
 473   if (!received_packet_manager_.IsAwaitingPacket(
 474           header.packet_sequence_number)) {
 475     DVLOG(1) << ENDPOINT << "Packet " << header.packet_sequence_number
 476              << " no longer being waited for.  Discarding.";
 477     if (debug_visitor_.get() != NULL) {
 478       debug_visitor_->OnDuplicatePacket(header.packet_sequence_number);
 479     }
 480     return false;
 481   }
 482
 483   if (version_negotiation_state_ != NEGOTIATED_VERSION) {
 484     if (is_server_) {
 485       if (!header.public_header.version_flag) {
 486         DLOG(WARNING) << ENDPOINT << "Packet " << header.packet_sequence_number
 487                       << " without version flag before version negotiated.";
 488         // Packets should have the version flag till version negotiation is
 489         // done.
 490         CloseConnection(QUIC_INVALID_VERSION, false);
 491         return false;
 492       } else {
 493         DCHECK_EQ(1u, header.public_header.versions.size());
 494         DCHECK_EQ(header.public_header.versions[0], version());
 495         version_negotiation_state_ = NEGOTIATED_VERSION;
 496         visitor_->OnSuccessfulVersionNegotiation(version());
 497         if (debug_visitor_.get() != NULL) {
 498           debug_visitor_->OnSuccessfulVersionNegotiation(version());
 499         }
 500       }
 501     } else {
 502       DCHECK(!header.public_header.version_flag);
 503       // If the client gets a packet without the version flag from the server
 504       // it should stop sending version since the version negotiation is done.
 505       packet_generator_.StopSendingVersion();
 506       version_negotiation_state_ = NEGOTIATED_VERSION;
 507       visitor_->OnSuccessfulVersionNegotiation(version());
 508       if (debug_visitor_.get() != NULL) {
 509         debug_visitor_->OnSuccessfulVersionNegotiation(version());
 510       }
 511     }
 512   }
 513
 514   DCHECK_EQ(NEGOTIATED_VERSION, version_negotiation_state_);
 515
 516   --stats_.packets_dropped;
 517   DVLOG(1) << ENDPOINT << "Received packet header: " << header;
 518   last_header_ = header;
 519   DCHECK(connected_);
 520   return true;
 521 }
 522
 523 void QuicConnection::OnFecProtectedPayload(StringPiece payload) {
 524   DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
 525   DCHECK_NE(0u, last_header_.fec_group);
 526   QuicFecGroup* group = GetFecGroup();
 527   if (group != NULL) {
 528     group->Update(last_decrypted_packet_level_, last_header_, payload);
 529   }
 530 }
 531
 532 bool QuicConnection::OnStreamFrame(const QuicStreamFrame& frame) {
 533   DCHECK(connected_);
 534   if (debug_visitor_.get() != NULL) {
 535     debug_visitor_->OnStreamFrame(frame);
 536   }
 537   if (frame.stream_id != kCryptoStreamId &&
 538       last_decrypted_packet_level_ == ENCRYPTION_NONE) {
 539     DLOG(WARNING) << ENDPOINT
 540                   << "Received an unencrypted data frame: closing connection";
 541     SendConnectionClose(QUIC_UNENCRYPTED_STREAM_DATA);
 542     return false;
 543   }
 544   last_stream_frames_.push_back(frame);
 545   return true;
 546 }
 547
 548 bool QuicConnection::OnAckFrame(const QuicAckFrame& incoming_ack) {
 549   DCHECK(connected_);
 550   if (debug_visitor_.get() != NULL) {
 551     debug_visitor_->OnAckFrame(incoming_ack);
 552   }
 553   DVLOG(1) << ENDPOINT << "OnAckFrame: " << incoming_ack;
 554
 555   if (last_header_.packet_sequence_number <= largest_seen_packet_with_ack_) {
 556     DVLOG(1) << ENDPOINT << "Received an old ack frame: ignoring";
 557     return true;
 558   }
 559
 560   if (!ValidateAckFrame(incoming_ack)) {
 561     SendConnectionClose(QUIC_INVALID_ACK_DATA);
 562     return false;
 563   }
 564
 565   last_ack_frames_.push_back(incoming_ack);
 566   return connected_;
 567 }
 568
 569 void QuicConnection::ProcessAckFrame(const QuicAckFrame& incoming_ack) {
 570   largest_seen_packet_with_ack_ = last_header_.packet_sequence_number;
 571   sent_packet_manager_.OnIncomingAck(incoming_ack,
 572                                      time_of_last_received_packet_);
 573   sent_entropy_manager_.ClearEntropyBefore(
 574       sent_packet_manager_.least_packet_awaited_by_peer() - 1);
 575   if (sent_packet_manager_.HasPendingRetransmissions()) {
 576     WriteIfNotBlocked();
 577   }
 578
 579   // Always reset the retransmission alarm when an ack comes in, since we now
 580   // have a better estimate of the current rtt than when it was set.
 581   QuicTime retransmission_time = sent_packet_manager_.GetRetransmissionTime();
 582   retransmission_alarm_->Update(retransmission_time,
 583                                 QuicTime::Delta::FromMilliseconds(1));
 584 }
 585
 586 void QuicConnection::ProcessStopWaitingFrame(
 587     const QuicStopWaitingFrame& stop_waiting) {
 588   largest_seen_packet_with_stop_waiting_ = last_header_.packet_sequence_number;
 589   received_packet_manager_.UpdatePacketInformationSentByPeer(stop_waiting);
 590   // Possibly close any FecGroups which are now irrelevant.
 591   CloseFecGroupsBefore(stop_waiting.least_unacked + 1);
 592 }
 593
 594 bool QuicConnection::OnCongestionFeedbackFrame(
 595     const QuicCongestionFeedbackFrame& feedback) {
 596   DCHECK(connected_);
 597   if (debug_visitor_.get() != NULL) {
 598     debug_visitor_->OnCongestionFeedbackFrame(feedback);
 599   }
 600   last_congestion_frames_.push_back(feedback);
 601   return connected_;
 602 }
 603
 604 bool QuicConnection::OnStopWaitingFrame(const QuicStopWaitingFrame& frame) {
 605   DCHECK(connected_);
 606
 607   if (last_header_.packet_sequence_number <=
 608       largest_seen_packet_with_stop_waiting_) {
 609     DVLOG(1) << ENDPOINT << "Received an old stop waiting frame: ignoring";
 610     return true;
 611   }
 612
 613   if (!ValidateStopWaitingFrame(frame)) {
 614     SendConnectionClose(QUIC_INVALID_STOP_WAITING_DATA);
 615     return false;
 616   }
 617
 618   if (debug_visitor_.get() != NULL) {
 619     debug_visitor_->OnStopWaitingFrame(frame);
 620   }
 621
 622   last_stop_waiting_frames_.push_back(frame);
 623   return connected_;
 624 }
 625
 626 bool QuicConnection::OnPingFrame(const QuicPingFrame& frame) {
 627   DCHECK(connected_);
 628   if (debug_visitor_.get() != NULL) {
 629     debug_visitor_->OnPingFrame(frame);
 630   }
 631   last_ping_frames_.push_back(frame);
 632   return true;
 633 }
 634
 635 bool QuicConnection::ValidateAckFrame(const QuicAckFrame& incoming_ack) {
 636   if (incoming_ack.largest_observed > packet_generator_.sequence_number()) {
 637     DLOG(ERROR) << ENDPOINT << "Peer's observed unsent packet:"
 638                 << incoming_ack.largest_observed << " vs "
 639                 << packet_generator_.sequence_number();
 640     // We got an error for data we have not sent.  Error out.
 641     return false;
 642   }
 643
 644   if (incoming_ack.largest_observed < sent_packet_manager_.largest_observed()) {
 645     DLOG(ERROR) << ENDPOINT << "Peer's largest_observed packet decreased:"
 646                 << incoming_ack.largest_observed << " vs "
 647                 << sent_packet_manager_.largest_observed();
 648     // A new ack has a diminished largest_observed value.  Error out.
 649     // If this was an old packet, we wouldn't even have checked.
 650     return false;
 651   }
 652
 653   if (!incoming_ack.missing_packets.empty() &&
 654       *incoming_ack.missing_packets.rbegin() > incoming_ack.largest_observed) {
 655     DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
 656                 << *incoming_ack.missing_packets.rbegin()
 657                 << " which is greater than largest observed: "
 658                 << incoming_ack.largest_observed;
 659     return false;
 660   }
 661
 662   if (!incoming_ack.missing_packets.empty() &&
 663       *incoming_ack.missing_packets.begin() <
 664       sent_packet_manager_.least_packet_awaited_by_peer()) {
 665     DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
 666                 << *incoming_ack.missing_packets.begin()
 667                 << " which is smaller than least_packet_awaited_by_peer_: "
 668                 << sent_packet_manager_.least_packet_awaited_by_peer();
 669     return false;
 670   }
 671
 672   if (!sent_entropy_manager_.IsValidEntropy(
 673           incoming_ack.largest_observed,
 674           incoming_ack.missing_packets,
 675           incoming_ack.entropy_hash)) {
 676     DLOG(ERROR) << ENDPOINT << "Peer sent invalid entropy.";
 677     return false;
 678   }
 679
 680   for (SequenceNumberSet::const_iterator iter =
 681            incoming_ack.revived_packets.begin();
 682        iter != incoming_ack.revived_packets.end(); ++iter) {
 683     if (!ContainsKey(incoming_ack.missing_packets, *iter)) {
 684       DLOG(ERROR) << ENDPOINT
 685                   << "Peer specified revived packet which was not missing.";
 686       return false;
 687     }
 688   }
 689   return true;
 690 }
 691
 692 bool QuicConnection::ValidateStopWaitingFrame(
 693     const QuicStopWaitingFrame& stop_waiting) {
 694   if (stop_waiting.least_unacked <
 695       received_packet_manager_.peer_least_packet_awaiting_ack()) {
 696     DLOG(ERROR) << ENDPOINT << "Peer's sent low least_unacked: "
 697                 << stop_waiting.least_unacked << " vs "
 698                 << received_packet_manager_.peer_least_packet_awaiting_ack();
 699     // We never process old ack frames, so this number should only increase.
 700     return false;
 701   }
 702
 703   if (stop_waiting.least_unacked >
 704       last_header_.packet_sequence_number) {
 705     DLOG(ERROR) << ENDPOINT << "Peer sent least_unacked:"
 706                 << stop_waiting.least_unacked
 707                 << " greater than the enclosing packet sequence number:"
 708                 << last_header_.packet_sequence_number;
 709     return false;
 710   }
 711
 712   return true;
 713 }
 714
 715 void QuicConnection::OnFecData(const QuicFecData& fec) {
 716   DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
 717   DCHECK_NE(0u, last_header_.fec_group);
 718   QuicFecGroup* group = GetFecGroup();
 719   if (group != NULL) {
 720     group->UpdateFec(last_decrypted_packet_level_,
 721                      last_header_.packet_sequence_number, fec);
 722   }
 723 }
 724
 725 bool QuicConnection::OnRstStreamFrame(const QuicRstStreamFrame& frame) {
 726   DCHECK(connected_);
 727   if (debug_visitor_.get() != NULL) {
 728     debug_visitor_->OnRstStreamFrame(frame);
 729   }
 730   DVLOG(1) << ENDPOINT << "Stream reset with error "
 731            << QuicUtils::StreamErrorToString(frame.error_code);
 732   last_rst_frames_.push_back(frame);
 733   return connected_;
 734 }
 735
 736 bool QuicConnection::OnConnectionCloseFrame(
 737     const QuicConnectionCloseFrame& frame) {
 738   DCHECK(connected_);
 739   if (debug_visitor_.get() != NULL) {
 740     debug_visitor_->OnConnectionCloseFrame(frame);
 741   }
 742   DVLOG(1) << ENDPOINT << "Connection " << connection_id()
 743            << " closed with error "
 744            << QuicUtils::ErrorToString(frame.error_code)
 745            << " " << frame.error_details;
 746   last_close_frames_.push_back(frame);
 747   return connected_;
 748 }
 749
 750 bool QuicConnection::OnGoAwayFrame(const QuicGoAwayFrame& frame) {
 751   DCHECK(connected_);
 752   if (debug_visitor_.get() != NULL) {
 753     debug_visitor_->OnGoAwayFrame(frame);
 754   }
 755   DVLOG(1) << ENDPOINT << "Go away received with error "
 756            << QuicUtils::ErrorToString(frame.error_code)
 757            << " and reason:" << frame.reason_phrase;
 758   last_goaway_frames_.push_back(frame);
 759   return connected_;
 760 }
 761
 762 bool QuicConnection::OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) {
 763   DCHECK(connected_);
 764   if (debug_visitor_.get() != NULL) {
 765     debug_visitor_->OnWindowUpdateFrame(frame);
 766   }
 767   DVLOG(1) << ENDPOINT << "WindowUpdate received for stream: "
 768            << frame.stream_id << " with byte offset: " << frame.byte_offset;
 769   last_window_update_frames_.push_back(frame);
 770   return connected_;
 771 }
 772
 773 bool QuicConnection::OnBlockedFrame(const QuicBlockedFrame& frame) {
 774   DCHECK(connected_);
 775   if (debug_visitor_.get() != NULL) {
 776     debug_visitor_->OnBlockedFrame(frame);
 777   }
 778   DVLOG(1) << ENDPOINT << "Blocked frame received for stream: "
 779            << frame.stream_id;
 780   last_blocked_frames_.push_back(frame);
 781   return connected_;
 782 }
 783
 784 void QuicConnection::OnPacketComplete() {
 785   // Don't do anything if this packet closed the connection.
 786   if (!connected_) {
 787     ClearLastFrames();
 788     return;
 789   }
 790
 791   DVLOG(1) << ENDPOINT << (last_packet_revived_ ? "Revived" : "Got")
 792            << " packet " << last_header_.packet_sequence_number
 793            << " with " << last_stream_frames_.size()<< " stream frames "
 794            << last_ack_frames_.size() << " acks, "
 795            << last_congestion_frames_.size() << " congestions, "
 796            << last_stop_waiting_frames_.size() << " stop_waiting, "
 797            << last_rst_frames_.size() << " rsts, "
 798            << last_goaway_frames_.size() << " goaways, "
 799            << last_window_update_frames_.size() << " window updates, "
 800            << last_blocked_frames_.size() << " blocked, "
 801            << last_ping_frames_.size() << " pings, "
 802            << last_close_frames_.size() << " closes, "
 803            << "for " << last_header_.public_header.connection_id;
 804
 805   ++num_packets_received_since_last_ack_sent_;
 806
 807   // Call MaybeQueueAck() before recording the received packet, since we want
 808   // to trigger an ack if the newly received packet was previously missing.
 809   MaybeQueueAck();
 810
 811   // Record received or revived packet to populate ack info correctly before
 812   // processing stream frames, since the processing may result in a response
 813   // packet with a bundled ack.
 814   if (last_packet_revived_) {
 815     received_packet_manager_.RecordPacketRevived(
 816         last_header_.packet_sequence_number);
 817   } else {
 818     received_packet_manager_.RecordPacketReceived(
 819         last_size_, last_header_, time_of_last_received_packet_);
 820   }
 821
 822   if (!last_stream_frames_.empty()) {
 823     visitor_->OnStreamFrames(last_stream_frames_);
 824   }
 825
 826   for (size_t i = 0; i < last_stream_frames_.size(); ++i) {
 827     stats_.stream_bytes_received +=
 828         last_stream_frames_[i].data.TotalBufferSize();
 829   }
 830
 831   // Process window updates, blocked, stream resets, acks, then congestion
 832   // feedback.
 833   if (!last_window_update_frames_.empty()) {
 834     visitor_->OnWindowUpdateFrames(last_window_update_frames_);
 835   }
 836   if (!last_blocked_frames_.empty()) {
 837     visitor_->OnBlockedFrames(last_blocked_frames_);
 838   }
 839   for (size_t i = 0; i < last_goaway_frames_.size(); ++i) {
 840     visitor_->OnGoAway(last_goaway_frames_[i]);
 841   }
 842   for (size_t i = 0; i < last_rst_frames_.size(); ++i) {
 843     visitor_->OnRstStream(last_rst_frames_[i]);
 844   }
 845   for (size_t i = 0; i < last_ack_frames_.size(); ++i) {
 846     ProcessAckFrame(last_ack_frames_[i]);
 847   }
 848   for (size_t i = 0; i < last_congestion_frames_.size(); ++i) {
 849     sent_packet_manager_.OnIncomingQuicCongestionFeedbackFrame(
 850         last_congestion_frames_[i], time_of_last_received_packet_);
 851   }
 852   for (size_t i = 0; i < last_stop_waiting_frames_.size(); ++i) {
 853     ProcessStopWaitingFrame(last_stop_waiting_frames_[i]);
 854   }
 855   if (!last_close_frames_.empty()) {
 856     CloseConnection(last_close_frames_[0].error_code, true);
 857     DCHECK(!connected_);
 858   }
 859
 860   // If there are new missing packets to report, send an ack immediately.
 861   if (received_packet_manager_.HasNewMissingPackets()) {
 862     ack_queued_ = true;
 863     ack_alarm_->Cancel();
 864   }
 865
 866   UpdateStopWaitingCount();
 867
 868   ClearLastFrames();
 869 }
 870
 871 void QuicConnection::MaybeQueueAck() {
 872   // If the incoming packet was missing, send an ack immediately.
 873   ack_queued_ = received_packet_manager_.IsMissing(
 874       last_header_.packet_sequence_number);
 875
 876   if (!ack_queued_ && ShouldLastPacketInstigateAck()) {
 877     if (ack_alarm_->IsSet()) {
 878       ack_queued_ = true;
 879     } else {
 880       // Send an ack much more quickly for crypto handshake packets.
 881       QuicTime::Delta delayed_ack_time = sent_packet_manager_.DelayedAckTime();
 882       if (last_stream_frames_.size() == 1 &&
 883           last_stream_frames_[0].stream_id == kCryptoStreamId) {
 884         delayed_ack_time = QuicTime::Delta::Zero();
 885       }
 886       ack_alarm_->Set(clock_->ApproximateNow().Add(delayed_ack_time));
 887       DVLOG(1) << "Ack timer set; next packet or timer will trigger ACK.";
 888     }
 889   }
 890
 891   if (ack_queued_) {
 892     ack_alarm_->Cancel();
 893   }
 894 }
 895
 896 void QuicConnection::ClearLastFrames() {
 897   last_stream_frames_.clear();
 898   last_ack_frames_.clear();
 899   last_congestion_frames_.clear();
 900   last_stop_waiting_frames_.clear();
 901   last_rst_frames_.clear();
 902   last_goaway_frames_.clear();
 903   last_window_update_frames_.clear();
 904   last_blocked_frames_.clear();
 905   last_ping_frames_.clear();
 906   last_close_frames_.clear();
 907 }
 908
 909 QuicAckFrame* QuicConnection::CreateAckFrame() {
 910   QuicAckFrame* outgoing_ack = new QuicAckFrame();
 911   received_packet_manager_.UpdateReceivedPacketInfo(
 912       outgoing_ack, clock_->ApproximateNow());
 913   DVLOG(1) << ENDPOINT << "Creating ack frame: " << *outgoing_ack;
 914   return outgoing_ack;
 915 }
 916
 917 QuicCongestionFeedbackFrame* QuicConnection::CreateFeedbackFrame() {
 918   return new QuicCongestionFeedbackFrame(outgoing_congestion_feedback_);
 919 }
 920
 921 QuicStopWaitingFrame* QuicConnection::CreateStopWaitingFrame() {
 922   QuicStopWaitingFrame stop_waiting;
 923   UpdateStopWaiting(&stop_waiting);
 924   return new QuicStopWaitingFrame(stop_waiting);
 925 }
 926
 927 bool QuicConnection::ShouldLastPacketInstigateAck() const {
 928   if (!last_stream_frames_.empty() ||
 929       !last_goaway_frames_.empty() ||
 930       !last_rst_frames_.empty() ||
 931       !last_window_update_frames_.empty() ||
 932       !last_blocked_frames_.empty() ||
 933       !last_ping_frames_.empty()) {
 934     return true;
 935   }
 936
 937   if (!last_ack_frames_.empty() && last_ack_frames_.back().is_truncated) {
 938     return true;
 939   }
 940   // Always send an ack every 20 packets in order to allow the peer to discard
 941   // information from the SentPacketManager and provide an RTT measurement.
 942   if (num_packets_received_since_last_ack_sent_ >=
 943           kMaxPacketsReceivedBeforeAckSend) {
 944     return true;
 945   }
 946   return false;
 947 }
 948
 949 void QuicConnection::UpdateStopWaitingCount() {
 950   if (last_ack_frames_.empty()) {
 951     return;
 952   }
 953
 954   // If the peer is still waiting for a packet that we are no longer planning to
 955   // send, send an ack to raise the high water mark.
 956   if (!last_ack_frames_.back().missing_packets.empty() &&
 957       GetLeastUnacked() > *last_ack_frames_.back().missing_packets.begin()) {
 958     ++stop_waiting_count_;
 959   } else {
 960     stop_waiting_count_ = 0;
 961   }
 962 }
 963
 964 QuicPacketSequenceNumber QuicConnection::GetLeastUnacked() const {
 965   return sent_packet_manager_.GetLeastUnacked();
 966 }
 967
 968 void QuicConnection::MaybeSendInResponseToPacket() {
 969   if (!connected_) {
 970     return;
 971   }
 972   ScopedPacketBundler bundler(this, ack_queued_ ? SEND_ACK : NO_ACK);
 973
 974   // Now that we have received an ack, we might be able to send packets which
 975   // are queued locally, or drain streams which are blocked.
 976   if (CanWrite(HAS_RETRANSMITTABLE_DATA)) {
 977     OnCanWrite();
 978   }
 979 }
 980
 981 void QuicConnection::SendVersionNegotiationPacket() {
 982   // TODO(alyssar): implement zero server state negotiation.
 983   pending_version_negotiation_packet_ = true;
 984   if (writer_->IsWriteBlocked()) {
 985     visitor_->OnWriteBlocked();
 986     return;
 987   }
 988   DVLOG(1) << ENDPOINT << "Sending version negotiation packet: {"
 989            << QuicVersionVectorToString(framer_.supported_versions()) << "}";
 990   scoped_ptr<QuicEncryptedPacket> version_packet(
 991       packet_generator_.SerializeVersionNegotiationPacket(
 992           framer_.supported_versions()));
 993   WriteResult result = writer_->WritePacket(
 994       version_packet->data(), version_packet->length(),
 995       self_address().address(), peer_address());
 996
 997   if (result.status == WRITE_STATUS_ERROR) {
 998     // We can't send an error as the socket is presumably borked.
 999     CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
1000     return;
1001   }
1002   if (result.status == WRITE_STATUS_BLOCKED) {
1003     visitor_->OnWriteBlocked();
1004     if (writer_->IsWriteBlockedDataBuffered()) {
1005       pending_version_negotiation_packet_ = false;
1006     }
1007     return;
1008   }
1009
1010   pending_version_negotiation_packet_ = false;
1011 }
1012
1013 QuicConsumedData QuicConnection::SendStreamData(
1014     QuicStreamId id,
1015     const IOVector& data,
1016     QuicStreamOffset offset,
1017     bool fin,
1018     FecProtection fec_protection,
1019     QuicAckNotifier::DelegateInterface* delegate) {
1020   if (!fin && data.Empty()) {
1021     LOG(DFATAL) << "Attempt to send empty stream frame";
1022   }
1023
1024   // This notifier will be owned by the AckNotifierManager (or deleted below if
1025   // no data or FIN was consumed).
1026   QuicAckNotifier* notifier = NULL;
1027   if (delegate) {
1028     notifier = new QuicAckNotifier(delegate);
1029   }
1030
1031   // Opportunistically bundle an ack with every outgoing packet.
1032   // Particularly, we want to bundle with handshake packets since we don't know
1033   // which decrypter will be used on an ack packet following a handshake
1034   // packet (a handshake packet from client to server could result in a REJ or a
1035   // SHLO from the server, leading to two different decrypters at the server.)
1036   //
1037   // TODO(jri): Note that ConsumeData may cause a response packet to be sent.
1038   // We may end up sending stale ack information if there are undecryptable
1039   // packets hanging around and/or there are revivable packets which may get
1040   // handled after this packet is sent. Change ScopedPacketBundler to do the
1041   // right thing: check ack_queued_, and then check undecryptable packets and
1042   // also if there is possibility of revival. Only bundle an ack if there's no
1043   // processing left that may cause received_info_ to change.
1044   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1045   QuicConsumedData consumed_data =
1046       packet_generator_.ConsumeData(id, data, offset, fin, fec_protection,
1047                                     notifier);
1048
1049   if (notifier &&
1050       (consumed_data.bytes_consumed == 0 && !consumed_data.fin_consumed)) {
1051     // No data was consumed, nor was a fin consumed, so delete the notifier.
1052     delete notifier;
1053   }
1054
1055   return consumed_data;
1056 }
1057
1058 void QuicConnection::SendRstStream(QuicStreamId id,
1059                                    QuicRstStreamErrorCode error,
1060                                    QuicStreamOffset bytes_written) {
1061   // Opportunistically bundle an ack with this outgoing packet.
1062   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1063   packet_generator_.AddControlFrame(QuicFrame(new QuicRstStreamFrame(
1064       id, AdjustErrorForVersion(error, version()), bytes_written)));
1065 }
1066
1067 void QuicConnection::SendWindowUpdate(QuicStreamId id,
1068                                       QuicStreamOffset byte_offset) {
1069   // Opportunistically bundle an ack with this outgoing packet.
1070   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1071   packet_generator_.AddControlFrame(
1072       QuicFrame(new QuicWindowUpdateFrame(id, byte_offset)));
1073 }
1074
1075 void QuicConnection::SendBlocked(QuicStreamId id) {
1076   // Opportunistically bundle an ack with this outgoing packet.
1077   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1078   packet_generator_.AddControlFrame(QuicFrame(new QuicBlockedFrame(id)));
1079 }
1080
1081 const QuicConnectionStats& QuicConnection::GetStats() {
1082   // Update rtt and estimated bandwidth.
1083   stats_.min_rtt_us =
1084       sent_packet_manager_.GetRttStats()->min_rtt().ToMicroseconds();
1085   stats_.srtt_us =
1086       sent_packet_manager_.GetRttStats()->SmoothedRtt().ToMicroseconds();
1087   stats_.estimated_bandwidth =
1088       sent_packet_manager_.BandwidthEstimate().ToBytesPerSecond();
1089   stats_.congestion_window = sent_packet_manager_.GetCongestionWindow();
1090   stats_.slow_start_threshold = sent_packet_manager_.GetSlowStartThreshold();
1091   stats_.max_packet_size = packet_generator_.max_packet_length();
1092   return stats_;
1093 }
1094
1095 void QuicConnection::ProcessUdpPacket(const IPEndPoint& self_address,
1096                                       const IPEndPoint& peer_address,
1097                                       const QuicEncryptedPacket& packet) {
1098   if (!connected_) {
1099     return;
1100   }
1101   if (debug_visitor_.get() != NULL) {
1102     debug_visitor_->OnPacketReceived(self_address, peer_address, packet);
1103   }
1104   last_packet_revived_ = false;
1105   last_size_ = packet.length();
1106
1107   CheckForAddressMigration(self_address, peer_address);
1108
1109   stats_.bytes_received += packet.length();
1110   ++stats_.packets_received;
1111
1112   if (!framer_.ProcessPacket(packet)) {
1113     // If we are unable to decrypt this packet, it might be
1114     // because the CHLO or SHLO packet was lost.
1115     if (framer_.error() == QUIC_DECRYPTION_FAILURE) {
1116       if (encryption_level_ != ENCRYPTION_FORWARD_SECURE &&
1117           undecryptable_packets_.size() < kMaxUndecryptablePackets) {
1118         QueueUndecryptablePacket(packet);
1119       } else if (debug_visitor_.get() != NULL) {
1120         debug_visitor_->OnUndecryptablePacket();
1121       }
1122     }
1123     DVLOG(1) << ENDPOINT << "Unable to process packet.  Last packet processed: "
1124              << last_header_.packet_sequence_number;
1125     return;
1126   }
1127
1128   ++stats_.packets_processed;
1129   MaybeProcessUndecryptablePackets();
1130   MaybeProcessRevivedPacket();
1131   MaybeSendInResponseToPacket();
1132   SetPingAlarm();
1133 }
1134
1135 void QuicConnection::CheckForAddressMigration(
1136     const IPEndPoint& self_address, const IPEndPoint& peer_address) {
1137   peer_ip_changed_ = false;
1138   peer_port_changed_ = false;
1139   self_ip_changed_ = false;
1140   self_port_changed_ = false;
1141
1142   if (peer_address_.address().empty()) {
1143     peer_address_ = peer_address;
1144   }
1145   if (self_address_.address().empty()) {
1146     self_address_ = self_address;
1147   }
1148
1149   if (!peer_address.address().empty() && !peer_address_.address().empty()) {
1150     peer_ip_changed_ = (peer_address.address() != peer_address_.address());
1151     peer_port_changed_ = (peer_address.port() != peer_address_.port());
1152
1153     // Store in case we want to migrate connection in ProcessValidatedPacket.
1154     migrating_peer_port_ = peer_address.port();
1155   }
1156
1157   if (!self_address.address().empty() && !self_address_.address().empty()) {
1158     self_ip_changed_ = (self_address.address() != self_address_.address());
1159     self_port_changed_ = (self_address.port() != self_address_.port());
1160   }
1161 }
1162
1163 void QuicConnection::OnCanWrite() {
1164   DCHECK(!writer_->IsWriteBlocked());
1165
1166   WriteQueuedPackets();
1167   WritePendingRetransmissions();
1168
1169   // Sending queued packets may have caused the socket to become write blocked,
1170   // or the congestion manager to prohibit sending.  If we've sent everything
1171   // we had queued and we're still not blocked, let the visitor know it can
1172   // write more.
1173   if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1174     return;
1175   }
1176
1177   {  // Limit the scope of the bundler.
1178     // Set |include_ack| to false in bundler; ack inclusion happens elsewhere.
1179     ScopedPacketBundler bundler(this, NO_ACK);
1180     visitor_->OnCanWrite();
1181   }
1182
1183   // After the visitor writes, it may have caused the socket to become write
1184   // blocked or the congestion manager to prohibit sending, so check again.
1185   if (visitor_->WillingAndAbleToWrite() &&
1186       !resume_writes_alarm_->IsSet() &&
1187       CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1188     // We're not write blocked, but some stream didn't write out all of its
1189     // bytes. Register for 'immediate' resumption so we'll keep writing after
1190     // other connections and events have had a chance to use the thread.
1191     resume_writes_alarm_->Set(clock_->ApproximateNow());
1192   }
1193 }
1194
1195 void QuicConnection::WriteIfNotBlocked() {
1196   if (!writer_->IsWriteBlocked()) {
1197     OnCanWrite();
1198   }
1199 }
1200
1201 bool QuicConnection::ProcessValidatedPacket() {
1202   if (peer_ip_changed_ || self_ip_changed_ || self_port_changed_) {
1203     SendConnectionCloseWithDetails(
1204         QUIC_ERROR_MIGRATING_ADDRESS,
1205         "Neither IP address migration, nor self port migration are supported.");
1206     return false;
1207   }
1208
1209   // Peer port migration is supported, do it now if port has changed.
1210   if (peer_port_changed_) {
1211     DVLOG(1) << ENDPOINT << "Peer's port changed from "
1212              << peer_address_.port() << " to " << migrating_peer_port_
1213              << ", migrating connection.";
1214     peer_address_ = IPEndPoint(peer_address_.address(), migrating_peer_port_);
1215   }
1216
1217   time_of_last_received_packet_ = clock_->Now();
1218   DVLOG(1) << ENDPOINT << "time of last received packet: "
1219            << time_of_last_received_packet_.ToDebuggingValue();
1220
1221   if (is_server_ && encryption_level_ == ENCRYPTION_NONE &&
1222       last_size_ > packet_generator_.max_packet_length()) {
1223     packet_generator_.set_max_packet_length(last_size_);
1224   }
1225   return true;
1226 }
1227
1228 void QuicConnection::WriteQueuedPackets() {
1229   DCHECK(!writer_->IsWriteBlocked());
1230
1231   if (pending_version_negotiation_packet_) {
1232     SendVersionNegotiationPacket();
1233   }
1234
1235   QueuedPacketList::iterator packet_iterator = queued_packets_.begin();
1236   while (packet_iterator != queued_packets_.end() &&
1237          WritePacket(&(*packet_iterator))) {
1238     packet_iterator = queued_packets_.erase(packet_iterator);
1239   }
1240 }
1241
1242 void QuicConnection::WritePendingRetransmissions() {
1243   // Keep writing as long as there's a pending retransmission which can be
1244   // written.
1245   while (sent_packet_manager_.HasPendingRetransmissions()) {
1246     const QuicSentPacketManager::PendingRetransmission pending =
1247         sent_packet_manager_.NextPendingRetransmission();
1248     if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1249       break;
1250     }
1251
1252     // Re-packetize the frames with a new sequence number for retransmission.
1253     // Retransmitted data packets do not use FEC, even when it's enabled.
1254     // Retransmitted packets use the same sequence number length as the
1255     // original.
1256     // Flush the packet generator before making a new packet.
1257     // TODO(ianswett): Implement ReserializeAllFrames as a separate path that
1258     // does not require the creator to be flushed.
1259     packet_generator_.FlushAllQueuedFrames();
1260     SerializedPacket serialized_packet = packet_generator_.ReserializeAllFrames(
1261         pending.retransmittable_frames.frames(),
1262         pending.sequence_number_length);
1263
1264     DVLOG(1) << ENDPOINT << "Retransmitting " << pending.sequence_number
1265              << " as " << serialized_packet.sequence_number;
1266     SendOrQueuePacket(
1267         QueuedPacket(serialized_packet,
1268                      pending.retransmittable_frames.encryption_level(),
1269                      pending.transmission_type,
1270                      pending.sequence_number));
1271   }
1272 }
1273
1274 void QuicConnection::RetransmitUnackedPackets(
1275     TransmissionType retransmission_type) {
1276   sent_packet_manager_.RetransmitUnackedPackets(retransmission_type);
1277
1278   WriteIfNotBlocked();
1279 }
1280
1281 void QuicConnection::NeuterUnencryptedPackets() {
1282   sent_packet_manager_.NeuterUnencryptedPackets();
1283   // This may have changed the retransmission timer, so re-arm it.
1284   QuicTime retransmission_time = sent_packet_manager_.GetRetransmissionTime();
1285   retransmission_alarm_->Update(retransmission_time,
1286                                 QuicTime::Delta::FromMilliseconds(1));
1287 }
1288
1289 bool QuicConnection::ShouldGeneratePacket(
1290     TransmissionType transmission_type,
1291     HasRetransmittableData retransmittable,
1292     IsHandshake handshake) {
1293   // We should serialize handshake packets immediately to ensure that they
1294   // end up sent at the right encryption level.
1295   if (handshake == IS_HANDSHAKE) {
1296     return true;
1297   }
1298
1299   return CanWrite(retransmittable);
1300 }
1301
1302 bool QuicConnection::CanWrite(HasRetransmittableData retransmittable) {
1303   if (!connected_) {
1304     return false;
1305   }
1306
1307   if (writer_->IsWriteBlocked()) {
1308     visitor_->OnWriteBlocked();
1309     return false;
1310   }
1311
1312   QuicTime now = clock_->Now();
1313   QuicTime::Delta delay = sent_packet_manager_.TimeUntilSend(
1314       now, retransmittable);
1315   if (delay.IsInfinite()) {
1316     send_alarm_->Cancel();
1317     return false;
1318   }
1319
1320   // If the scheduler requires a delay, then we can not send this packet now.
1321   if (!delay.IsZero()) {
1322     send_alarm_->Update(now.Add(delay), QuicTime::Delta::FromMilliseconds(1));
1323     DVLOG(1) << "Delaying sending.";
1324     return false;
1325   }
1326   send_alarm_->Cancel();
1327   return true;
1328 }
1329
1330 bool QuicConnection::WritePacket(QueuedPacket* packet) {
1331   if (!WritePacketInner(packet)) {
1332     return false;
1333   }
1334   delete packet->serialized_packet.retransmittable_frames;
1335   delete packet->serialized_packet.packet;
1336   packet->serialized_packet.retransmittable_frames = NULL;
1337   packet->serialized_packet.packet = NULL;
1338   return true;
1339 }
1340
1341 bool QuicConnection::WritePacketInner(QueuedPacket* packet) {
1342   if (ShouldDiscardPacket(*packet)) {
1343     ++stats_.packets_discarded;
1344     return true;
1345   }
1346   // Connection close packets are encrypted and saved, so don't exit early.
1347   if (writer_->IsWriteBlocked() && !IsConnectionClose(*packet)) {
1348     return false;
1349   }
1350
1351   QuicPacketSequenceNumber sequence_number =
1352       packet->serialized_packet.sequence_number;
1353   // Some encryption algorithms require the packet sequence numbers not be
1354   // repeated.
1355   DCHECK_LE(sequence_number_of_last_sent_packet_, sequence_number);
1356   sequence_number_of_last_sent_packet_ = sequence_number;
1357
1358   QuicEncryptedPacket* encrypted = framer_.EncryptPacket(
1359       packet->encryption_level,
1360       sequence_number,
1361       *packet->serialized_packet.packet);
1362   if (encrypted == NULL) {
1363     LOG(DFATAL) << ENDPOINT << "Failed to encrypt packet number "
1364                 << sequence_number;
1365     // CloseConnection does not send close packet, so no infinite loop here.
1366     CloseConnection(QUIC_ENCRYPTION_FAILURE, false);
1367     return false;
1368   }
1369
1370   // Connection close packets are eventually owned by TimeWaitListManager.
1371   // Others are deleted at the end of this call.
1372   scoped_ptr<QuicEncryptedPacket> encrypted_deleter;
1373   if (IsConnectionClose(*packet)) {
1374     DCHECK(connection_close_packet_.get() == NULL);
1375     connection_close_packet_.reset(encrypted);
1376     // This assures we won't try to write *forced* packets when blocked.
1377     // Return true to stop processing.
1378     if (writer_->IsWriteBlocked()) {
1379       visitor_->OnWriteBlocked();
1380       return true;
1381     }
1382   } else {
1383     encrypted_deleter.reset(encrypted);
1384   }
1385
1386   if (!FLAGS_quic_allow_oversized_packets_for_test) {
1387     DCHECK_LE(encrypted->length(), kMaxPacketSize);
1388   }
1389   DCHECK_LE(encrypted->length(), packet_generator_.max_packet_length());
1390   DVLOG(1) << ENDPOINT << "Sending packet " << sequence_number << " : "
1391            << (packet->serialized_packet.packet->is_fec_packet() ? "FEC " :
1392                (IsRetransmittable(*packet) == HAS_RETRANSMITTABLE_DATA
1393                 ? "data bearing " : " ack only "))
1394            << ", encryption level: "
1395            << QuicUtils::EncryptionLevelToString(packet->encryption_level)
1396            << ", length:"
1397            << packet->serialized_packet.packet->length()
1398            << ", encrypted length:"
1399            << encrypted->length();
1400   DVLOG(2) << ENDPOINT << "packet(" << sequence_number << "): " << std::endl
1401            << QuicUtils::StringToHexASCIIDump(
1402                packet->serialized_packet.packet->AsStringPiece());
1403
1404   WriteResult result = writer_->WritePacket(encrypted->data(),
1405                                             encrypted->length(),
1406                                             self_address().address(),
1407                                             peer_address());
1408   if (result.error_code == ERR_IO_PENDING) {
1409     DCHECK_EQ(WRITE_STATUS_BLOCKED, result.status);
1410   }
1411   if (debug_visitor_.get() != NULL) {
1412     // Pass the write result to the visitor.
1413     debug_visitor_->OnPacketSent(sequence_number,
1414                                  packet->encryption_level,
1415                                  packet->transmission_type,
1416                                  *encrypted,
1417                                  result);
1418   }
1419
1420   if (result.status == WRITE_STATUS_BLOCKED) {
1421     visitor_->OnWriteBlocked();
1422     // If the socket buffers the the data, then the packet should not
1423     // be queued and sent again, which would result in an unnecessary
1424     // duplicate packet being sent.  The helper must call OnCanWrite
1425     // when the write completes, and OnWriteError if an error occurs.
1426     if (!writer_->IsWriteBlockedDataBuffered()) {
1427       return false;
1428     }
1429   }
1430   QuicTime now = clock_->Now();
1431   if (packet->transmission_type == NOT_RETRANSMISSION) {
1432     time_of_last_sent_new_packet_ = now;
1433   }
1434   SetPingAlarm();
1435   DVLOG(1) << ENDPOINT << "time of last sent packet: "
1436            << now.ToDebuggingValue();
1437
1438   // TODO(ianswett): Change the sequence number length and other packet creator
1439   // options by a more explicit API than setting a struct value directly,
1440   // perhaps via the NetworkChangeVisitor.
1441   packet_generator_.UpdateSequenceNumberLength(
1442       sent_packet_manager_.least_packet_awaited_by_peer(),
1443       sent_packet_manager_.GetCongestionWindow());
1444
1445   if (packet->original_sequence_number == 0) {
1446     sent_packet_manager_.OnSerializedPacket(packet->serialized_packet);
1447   } else {
1448     if (debug_visitor_.get() != NULL) {
1449       debug_visitor_->OnPacketRetransmitted(
1450           packet->original_sequence_number, sequence_number);
1451     }
1452     sent_packet_manager_.OnRetransmittedPacket(packet->original_sequence_number,
1453                                                sequence_number);
1454   }
1455   bool reset_retransmission_alarm = sent_packet_manager_.OnPacketSent(
1456       sequence_number,
1457       now,
1458       encrypted->length(),
1459       packet->transmission_type,
1460       IsRetransmittable(*packet));
1461   // The SentPacketManager now owns the retransmittable frames.
1462   packet->serialized_packet.retransmittable_frames = NULL;
1463
1464   if (reset_retransmission_alarm || !retransmission_alarm_->IsSet()) {
1465     retransmission_alarm_->Update(sent_packet_manager_.GetRetransmissionTime(),
1466                                   QuicTime::Delta::FromMilliseconds(1));
1467   }
1468
1469   stats_.bytes_sent += result.bytes_written;
1470   ++stats_.packets_sent;
1471   if (packet->transmission_type != NOT_RETRANSMISSION) {
1472     stats_.bytes_retransmitted += result.bytes_written;
1473     ++stats_.packets_retransmitted;
1474   }
1475
1476   if (result.status == WRITE_STATUS_ERROR) {
1477     OnWriteError(result.error_code);
1478     return false;
1479   }
1480
1481   return true;
1482 }
1483
1484 bool QuicConnection::ShouldDiscardPacket(const QueuedPacket& packet) {
1485   if (!connected_) {
1486     DVLOG(1) << ENDPOINT
1487              << "Not sending packet as connection is disconnected.";
1488     return true;
1489   }
1490
1491   QuicPacketSequenceNumber sequence_number =
1492       packet.serialized_packet.sequence_number;
1493   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE &&
1494       packet.encryption_level == ENCRYPTION_NONE) {
1495     // Drop packets that are NULL encrypted since the peer won't accept them
1496     // anymore.
1497     DVLOG(1) << ENDPOINT << "Dropping NULL encrypted packet: "
1498              << sequence_number << " since the connection is forward secure.";
1499     return true;
1500   }
1501
1502   // If a retransmission has been acked before sending, don't send it.
1503   // This occurs if a packet gets serialized, queued, then discarded.
1504   if (packet.transmission_type != NOT_RETRANSMISSION &&
1505       (!sent_packet_manager_.IsUnacked(packet.original_sequence_number) ||
1506        !sent_packet_manager_.HasRetransmittableFrames(
1507            packet.original_sequence_number))) {
1508     DVLOG(1) << ENDPOINT << "Dropping unacked packet: " << sequence_number
1509              << " A previous transmission was acked while write blocked.";
1510     return true;
1511   }
1512
1513   return false;
1514 }
1515
1516 void QuicConnection::OnWriteError(int error_code) {
1517   DVLOG(1) << ENDPOINT << "Write failed with error: " << error_code
1518            << " (" << ErrorToString(error_code) << ")";
1519   // We can't send an error as the socket is presumably borked.
1520   CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
1521 }
1522
1523 void QuicConnection::OnSerializedPacket(
1524     const SerializedPacket& serialized_packet) {
1525   if (serialized_packet.retransmittable_frames) {
1526     serialized_packet.retransmittable_frames->
1527         set_encryption_level(encryption_level_);
1528   }
1529   SendOrQueuePacket(QueuedPacket(serialized_packet, encryption_level_));
1530 }
1531
1532 void QuicConnection::OnCongestionWindowChange(QuicByteCount congestion_window) {
1533   packet_generator_.OnCongestionWindowChange(congestion_window);
1534   visitor_->OnCongestionWindowChange(clock_->ApproximateNow());
1535 }
1536
1537 void QuicConnection::OnHandshakeComplete() {
1538   sent_packet_manager_.SetHandshakeConfirmed();
1539 }
1540
1541 void QuicConnection::SendOrQueuePacket(QueuedPacket packet) {
1542   // The caller of this function is responsible for checking CanWrite().
1543   if (packet.serialized_packet.packet == NULL) {
1544     LOG(DFATAL) << "NULL packet passed in to SendOrQueuePacket";
1545     return;
1546   }
1547
1548   sent_entropy_manager_.RecordPacketEntropyHash(
1549       packet.serialized_packet.sequence_number,
1550       packet.serialized_packet.entropy_hash);
1551   LOG_IF(DFATAL, !queued_packets_.empty() && !writer_->IsWriteBlocked())
1552       << "Packets should only be left queued if we're write blocked.";
1553   if (!WritePacket(&packet)) {
1554     queued_packets_.push_back(packet);
1555   }
1556 }
1557
1558 void QuicConnection::UpdateStopWaiting(QuicStopWaitingFrame* stop_waiting) {
1559   stop_waiting->least_unacked = GetLeastUnacked();
1560   stop_waiting->entropy_hash = sent_entropy_manager_.GetCumulativeEntropy(
1561       stop_waiting->least_unacked - 1);
1562 }
1563
1564 void QuicConnection::SendPing() {
1565   if (retransmission_alarm_->IsSet()) {
1566     return;
1567   }
1568   if (version() == QUIC_VERSION_16) {
1569     // TODO(rch): remove this when we remove version 15 and 16.
1570     // This is a horrible hideous hack which we should not support.
1571     IOVector data;
1572     char c_data[] = "C";
1573     data.Append(c_data, 1);
1574     QuicConsumedData consumed_data =
1575         packet_generator_.ConsumeData(kCryptoStreamId, data, 0, false,
1576                                       MAY_FEC_PROTECT, NULL);
1577     if (consumed_data.bytes_consumed == 0) {
1578       DLOG(ERROR) << "Unable to send ping!?";
1579     }
1580   } else {
1581     packet_generator_.AddControlFrame(QuicFrame(new QuicPingFrame));
1582   }
1583 }
1584
1585 void QuicConnection::SendAck() {
1586   ack_alarm_->Cancel();
1587   stop_waiting_count_ = 0;
1588   num_packets_received_since_last_ack_sent_ = 0;
1589   bool send_feedback = false;
1590
1591   // Deprecating the Congestion Feedback Frame after QUIC_VERSION_22.
1592   if (version() <= QUIC_VERSION_22) {
1593     if (received_packet_manager_.GenerateCongestionFeedback(
1594             &outgoing_congestion_feedback_)) {
1595       DVLOG(1) << ENDPOINT << "Sending feedback: "
1596                << outgoing_congestion_feedback_;
1597       send_feedback = true;
1598     }
1599   }
1600
1601   packet_generator_.SetShouldSendAck(send_feedback, true);
1602 }
1603
1604 void QuicConnection::OnRetransmissionTimeout() {
1605   if (!sent_packet_manager_.HasUnackedPackets()) {
1606     return;
1607   }
1608
1609   sent_packet_manager_.OnRetransmissionTimeout();
1610   WriteIfNotBlocked();
1611
1612   // A write failure can result in the connection being closed, don't attempt to
1613   // write further packets, or to set alarms.
1614   if (!connected_) {
1615     return;
1616   }
1617
1618   // In the TLP case, the SentPacketManager gives the connection the opportunity
1619   // to send new data before retransmitting.
1620   if (sent_packet_manager_.MaybeRetransmitTailLossProbe()) {
1621     // Send the pending retransmission now that it's been queued.
1622     WriteIfNotBlocked();
1623   }
1624
1625   // Ensure the retransmission alarm is always set if there are unacked packets
1626   // and nothing waiting to be sent.
1627   if (!HasQueuedData() && !retransmission_alarm_->IsSet()) {
1628     QuicTime rto_timeout = sent_packet_manager_.GetRetransmissionTime();
1629     if (rto_timeout.IsInitialized()) {
1630       retransmission_alarm_->Set(rto_timeout);
1631     }
1632   }
1633 }
1634
1635 void QuicConnection::SetEncrypter(EncryptionLevel level,
1636                                   QuicEncrypter* encrypter) {
1637   framer_.SetEncrypter(level, encrypter);
1638 }
1639
1640 const QuicEncrypter* QuicConnection::encrypter(EncryptionLevel level) const {
1641   return framer_.encrypter(level);
1642 }
1643
1644 void QuicConnection::SetDefaultEncryptionLevel(EncryptionLevel level) {
1645   encryption_level_ = level;
1646   packet_generator_.set_encryption_level(level);
1647 }
1648
1649 void QuicConnection::SetDecrypter(QuicDecrypter* decrypter,
1650                                   EncryptionLevel level) {
1651   framer_.SetDecrypter(decrypter, level);
1652 }
1653
1654 void QuicConnection::SetAlternativeDecrypter(QuicDecrypter* decrypter,
1655                                              EncryptionLevel level,
1656                                              bool latch_once_used) {
1657   framer_.SetAlternativeDecrypter(decrypter, level, latch_once_used);
1658 }
1659
1660 const QuicDecrypter* QuicConnection::decrypter() const {
1661   return framer_.decrypter();
1662 }
1663
1664 const QuicDecrypter* QuicConnection::alternative_decrypter() const {
1665   return framer_.alternative_decrypter();
1666 }
1667
1668 void QuicConnection::QueueUndecryptablePacket(
1669     const QuicEncryptedPacket& packet) {
1670   DVLOG(1) << ENDPOINT << "Queueing undecryptable packet.";
1671   undecryptable_packets_.push_back(packet.Clone());
1672 }
1673
1674 void QuicConnection::MaybeProcessUndecryptablePackets() {
1675   if (undecryptable_packets_.empty() || encryption_level_ == ENCRYPTION_NONE) {
1676     return;
1677   }
1678
1679   while (connected_ && !undecryptable_packets_.empty()) {
1680     DVLOG(1) << ENDPOINT << "Attempting to process undecryptable packet";
1681     QuicEncryptedPacket* packet = undecryptable_packets_.front();
1682     if (!framer_.ProcessPacket(*packet) &&
1683         framer_.error() == QUIC_DECRYPTION_FAILURE) {
1684       DVLOG(1) << ENDPOINT << "Unable to process undecryptable packet...";
1685       break;
1686     }
1687     DVLOG(1) << ENDPOINT << "Processed undecryptable packet!";
1688     ++stats_.packets_processed;
1689     delete packet;
1690     undecryptable_packets_.pop_front();
1691   }
1692
1693   // Once forward secure encryption is in use, there will be no
1694   // new keys installed and hence any undecryptable packets will
1695   // never be able to be decrypted.
1696   if (encryption_level_ == ENCRYPTION_FORWARD_SECURE) {
1697     if (debug_visitor_.get() != NULL) {
1698       // TODO(rtenneti): perhaps more efficient to pass the number of
1699       // undecryptable packets as the argument to OnUndecryptablePacket so that
1700       // we just need to call OnUndecryptablePacket once?
1701       for (size_t i = 0; i < undecryptable_packets_.size(); ++i) {
1702         debug_visitor_->OnUndecryptablePacket();
1703       }
1704     }
1705     STLDeleteElements(&undecryptable_packets_);
1706   }
1707 }
1708
1709 void QuicConnection::MaybeProcessRevivedPacket() {
1710   QuicFecGroup* group = GetFecGroup();
1711   if (!connected_ || group == NULL || !group->CanRevive()) {
1712     return;
1713   }
1714   QuicPacketHeader revived_header;
1715   char revived_payload[kMaxPacketSize];
1716   size_t len = group->Revive(&revived_header, revived_payload, kMaxPacketSize);
1717   revived_header.public_header.connection_id = connection_id_;
1718   revived_header.public_header.connection_id_length =
1719       last_header_.public_header.connection_id_length;
1720   revived_header.public_header.version_flag = false;
1721   revived_header.public_header.reset_flag = false;
1722   revived_header.public_header.sequence_number_length =
1723       last_header_.public_header.sequence_number_length;
1724   revived_header.fec_flag = false;
1725   revived_header.is_in_fec_group = NOT_IN_FEC_GROUP;
1726   revived_header.fec_group = 0;
1727   group_map_.erase(last_header_.fec_group);
1728   last_decrypted_packet_level_ = group->effective_encryption_level();
1729   DCHECK_LT(last_decrypted_packet_level_, NUM_ENCRYPTION_LEVELS);
1730   delete group;
1731
1732   last_packet_revived_ = true;
1733   if (debug_visitor_.get() != NULL) {
1734     debug_visitor_->OnRevivedPacket(revived_header,
1735                                     StringPiece(revived_payload, len));
1736   }
1737
1738   ++stats_.packets_revived;
1739   framer_.ProcessRevivedPacket(&revived_header,
1740                                StringPiece(revived_payload, len));
1741 }
1742
1743 QuicFecGroup* QuicConnection::GetFecGroup() {
1744   QuicFecGroupNumber fec_group_num = last_header_.fec_group;
1745   if (fec_group_num == 0) {
1746     return NULL;
1747   }
1748   if (group_map_.count(fec_group_num) == 0) {
1749     if (group_map_.size() >= kMaxFecGroups) {  // Too many groups
1750       if (fec_group_num < group_map_.begin()->first) {
1751         // The group being requested is a group we've seen before and deleted.
1752         // Don't recreate it.
1753         return NULL;
1754       }
1755       // Clear the lowest group number.
1756       delete group_map_.begin()->second;
1757       group_map_.erase(group_map_.begin());
1758     }
1759     group_map_[fec_group_num] = new QuicFecGroup();
1760   }
1761   return group_map_[fec_group_num];
1762 }
1763
1764 void QuicConnection::SendConnectionClose(QuicErrorCode error) {
1765   SendConnectionCloseWithDetails(error, string());
1766 }
1767
1768 void QuicConnection::SendConnectionCloseWithDetails(QuicErrorCode error,
1769                                                     const string& details) {
1770   // If we're write blocked, WritePacket() will not send, but will capture the
1771   // serialized packet.
1772   SendConnectionClosePacket(error, details);
1773   if (connected_) {
1774     // It's possible that while sending the connection close packet, we get a
1775     // socket error and disconnect right then and there.  Avoid a double
1776     // disconnect in that case.
1777     CloseConnection(error, false);
1778   }
1779 }
1780
1781 void QuicConnection::SendConnectionClosePacket(QuicErrorCode error,
1782                                                const string& details) {
1783   DVLOG(1) << ENDPOINT << "Force closing " << connection_id()
1784            << " with error " << QuicUtils::ErrorToString(error)
1785            << " (" << error << ") " << details;
1786   ScopedPacketBundler ack_bundler(this, SEND_ACK);
1787   QuicConnectionCloseFrame* frame = new QuicConnectionCloseFrame();
1788   frame->error_code = error;
1789   frame->error_details = details;
1790   packet_generator_.AddControlFrame(QuicFrame(frame));
1791   packet_generator_.FlushAllQueuedFrames();
1792 }
1793
1794 void QuicConnection::CloseConnection(QuicErrorCode error, bool from_peer) {
1795   if (!connected_) {
1796     DLOG(DFATAL) << "Error: attempt to close an already closed connection"
1797                  << base::debug::StackTrace().ToString();
1798     return;
1799   }
1800   connected_ = false;
1801   if (debug_visitor_.get() != NULL) {
1802     debug_visitor_->OnConnectionClosed(error, from_peer);
1803   }
1804   visitor_->OnConnectionClosed(error, from_peer);
1805   // Cancel the alarms so they don't trigger any action now that the
1806   // connection is closed.
1807   ack_alarm_->Cancel();
1808   ping_alarm_->Cancel();
1809   resume_writes_alarm_->Cancel();
1810   retransmission_alarm_->Cancel();
1811   send_alarm_->Cancel();
1812   timeout_alarm_->Cancel();
1813 }
1814
1815 void QuicConnection::SendGoAway(QuicErrorCode error,
1816                                 QuicStreamId last_good_stream_id,
1817                                 const string& reason) {
1818   DVLOG(1) << ENDPOINT << "Going away with error "
1819            << QuicUtils::ErrorToString(error)
1820            << " (" << error << ")";
1821
1822   // Opportunistically bundle an ack with this outgoing packet.
1823   ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1824   packet_generator_.AddControlFrame(
1825       QuicFrame(new QuicGoAwayFrame(error, last_good_stream_id, reason)));
1826 }
1827
1828 void QuicConnection::CloseFecGroupsBefore(
1829     QuicPacketSequenceNumber sequence_number) {
1830   FecGroupMap::iterator it = group_map_.begin();
1831   while (it != group_map_.end()) {
1832     // If this is the current group or the group doesn't protect this packet
1833     // we can ignore it.
1834     if (last_header_.fec_group == it->first ||
1835         !it->second->ProtectsPacketsBefore(sequence_number)) {
1836       ++it;
1837       continue;
1838     }
1839     QuicFecGroup* fec_group = it->second;
1840     DCHECK(!fec_group->CanRevive());
1841     FecGroupMap::iterator next = it;
1842     ++next;
1843     group_map_.erase(it);
1844     delete fec_group;
1845     it = next;
1846   }
1847 }
1848
1849 size_t QuicConnection::max_packet_length() const {
1850   return packet_generator_.max_packet_length();
1851 }
1852
1853 void QuicConnection::set_max_packet_length(size_t length) {
1854   return packet_generator_.set_max_packet_length(length);
1855 }
1856
1857 bool QuicConnection::HasQueuedData() const {
1858   return pending_version_negotiation_packet_ ||
1859       !queued_packets_.empty() || packet_generator_.HasQueuedFrames();
1860 }
1861
1862 bool QuicConnection::CanWriteStreamData() {
1863   // Don't write stream data if there are negotiation or queued data packets
1864   // to send. Otherwise, continue and bundle as many frames as possible.
1865   if (pending_version_negotiation_packet_ || !queued_packets_.empty()) {
1866     return false;
1867   }
1868
1869   IsHandshake pending_handshake = visitor_->HasPendingHandshake() ?
1870       IS_HANDSHAKE : NOT_HANDSHAKE;
1871   // Sending queued packets may have caused the socket to become write blocked,
1872   // or the congestion manager to prohibit sending.  If we've sent everything
1873   // we had queued and we're still not blocked, let the visitor know it can
1874   // write more.
1875   return ShouldGeneratePacket(NOT_RETRANSMISSION, HAS_RETRANSMITTABLE_DATA,
1876                               pending_handshake);
1877 }
1878
1879 void QuicConnection::SetIdleNetworkTimeout(QuicTime::Delta timeout) {
1880   // Adjust the idle timeout on client and server to prevent clients from
1881   // sending requests to servers which have already closed the connection.
1882   if (is_server_) {
1883     timeout = timeout.Add(QuicTime::Delta::FromSeconds(1));
1884   } else if (timeout > QuicTime::Delta::FromSeconds(1)) {
1885     timeout = timeout.Subtract(QuicTime::Delta::FromSeconds(1));
1886   }
1887
1888   if (timeout < idle_network_timeout_) {
1889     idle_network_timeout_ = timeout;
1890     CheckForTimeout();
1891   } else {
1892     idle_network_timeout_ = timeout;
1893   }
1894 }
1895
1896 void QuicConnection::SetOverallConnectionTimeout(QuicTime::Delta timeout) {
1897   if (timeout < overall_connection_timeout_) {
1898     overall_connection_timeout_ = timeout;
1899     CheckForTimeout();
1900   } else {
1901     overall_connection_timeout_ = timeout;
1902   }
1903 }
1904
1905 bool QuicConnection::CheckForTimeout() {
1906   QuicTime now = clock_->ApproximateNow();
1907   QuicTime time_of_last_packet = max(time_of_last_received_packet_,
1908                                      time_of_last_sent_new_packet_);
1909
1910   // If no packets have been sent or received, then don't timeout.
1911   if (FLAGS_quic_timeouts_require_activity &&
1912       !time_of_last_packet.IsInitialized()) {
1913     timeout_alarm_->Cancel();
1914     timeout_alarm_->Set(now.Add(idle_network_timeout_));
1915     return false;
1916   }
1917
1918   // |delta| can be < 0 as |now| is approximate time but |time_of_last_packet|
1919   // is accurate time. However, this should not change the behavior of
1920   // timeout handling.
1921   QuicTime::Delta delta = now.Subtract(time_of_last_packet);
1922   DVLOG(1) << ENDPOINT << "last packet "
1923            << time_of_last_packet.ToDebuggingValue()
1924            << " now:" << now.ToDebuggingValue()
1925            << " delta:" << delta.ToMicroseconds()
1926            << " network_timeout: " << idle_network_timeout_.ToMicroseconds();
1927   if (delta >= idle_network_timeout_) {
1928     DVLOG(1) << ENDPOINT << "Connection timedout due to no network activity.";
1929     SendConnectionClose(QUIC_CONNECTION_TIMED_OUT);
1930     return true;
1931   }
1932
1933   // Next timeout delta.
1934   QuicTime::Delta timeout = idle_network_timeout_.Subtract(delta);
1935
1936   if (!overall_connection_timeout_.IsInfinite()) {
1937     QuicTime::Delta connected_time =
1938         now.Subtract(stats_.connection_creation_time);
1939     DVLOG(1) << ENDPOINT << "connection time: "
1940              << connected_time.ToMilliseconds() << " overall timeout: "
1941              << overall_connection_timeout_.ToMilliseconds();
1942     if (connected_time >= overall_connection_timeout_) {
1943       DVLOG(1) << ENDPOINT <<
1944           "Connection timedout due to overall connection timeout.";
1945       SendConnectionClose(QUIC_CONNECTION_OVERALL_TIMED_OUT);
1946       return true;
1947     }
1948
1949     // Take the min timeout.
1950     QuicTime::Delta connection_timeout =
1951         overall_connection_timeout_.Subtract(connected_time);
1952     if (connection_timeout < timeout) {
1953       timeout = connection_timeout;
1954     }
1955   }
1956
1957   timeout_alarm_->Cancel();
1958   timeout_alarm_->Set(now.Add(timeout));
1959   return false;
1960 }
1961
1962 void QuicConnection::SetPingAlarm() {
1963   if (is_server_) {
1964     // Only clients send pings.
1965     return;
1966   }
1967   if (!visitor_->HasOpenDataStreams()) {
1968     ping_alarm_->Cancel();
1969     // Don't send a ping unless there are open streams.
1970     return;
1971   }
1972   QuicTime::Delta ping_timeout = QuicTime::Delta::FromSeconds(kPingTimeoutSecs);
1973   ping_alarm_->Update(clock_->ApproximateNow().Add(ping_timeout),
1974                       QuicTime::Delta::FromSeconds(1));
1975 }
1976
1977 QuicConnection::ScopedPacketBundler::ScopedPacketBundler(
1978     QuicConnection* connection,
1979     AckBundling send_ack)
1980     : connection_(connection),
1981       already_in_batch_mode_(connection != NULL &&
1982                              connection->packet_generator_.InBatchMode()) {
1983   if (connection_  == NULL) {
1984     return;
1985   }
1986   // Move generator into batch mode. If caller wants us to include an ack,
1987   // check the delayed-ack timer to see if there's ack info to be sent.
1988   if (!already_in_batch_mode_) {
1989     DVLOG(1) << "Entering Batch Mode.";
1990     connection_->packet_generator_.StartBatchOperations();
1991   }
1992   // Bundle an ack if the alarm is set or with every second packet if we need to
1993   // raise the peer's least unacked.
1994   bool ack_pending =
1995       connection_->ack_alarm_->IsSet() || connection_->stop_waiting_count_ > 1;
1996   if (send_ack == SEND_ACK || (send_ack == BUNDLE_PENDING_ACK && ack_pending)) {
1997     DVLOG(1) << "Bundling ack with outgoing packet.";
1998     connection_->SendAck();
1999   }
2000 }
2001
2002 QuicConnection::ScopedPacketBundler::~ScopedPacketBundler() {
2003   if (connection_  == NULL) {
2004     return;
2005   }
2006   // If we changed the generator's batch state, restore original batch state.
2007   if (!already_in_batch_mode_) {
2008     DVLOG(1) << "Leaving Batch Mode.";
2009     connection_->packet_generator_.FinishBatchOperations();
2010   }
2011   DCHECK_EQ(already_in_batch_mode_,
2012             connection_->packet_generator_.InBatchMode());
2013 }
2014
2015 HasRetransmittableData QuicConnection::IsRetransmittable(
2016     const QueuedPacket& packet) {
2017   // Retransmitted packets retransmittable frames are owned by the unacked
2018   // packet map, but are not present in the serialized packet.
2019   if (packet.transmission_type != NOT_RETRANSMISSION ||
2020       packet.serialized_packet.retransmittable_frames != NULL) {
2021     return HAS_RETRANSMITTABLE_DATA;
2022   } else {
2023     return NO_RETRANSMITTABLE_DATA;
2024   }
2025 }
2026
2027 bool QuicConnection::IsConnectionClose(
2028     QueuedPacket packet) {
2029   RetransmittableFrames* retransmittable_frames =
2030       packet.serialized_packet.retransmittable_frames;
2031   if (!retransmittable_frames) {
2032     return false;
2033   }
2034   for (size_t i = 0; i < retransmittable_frames->frames().size(); ++i) {
2035     if (retransmittable_frames->frames()[i].type == CONNECTION_CLOSE_FRAME) {
2036       return true;
2037     }
2038   }
2039   return false;
2040 }
2041
2042 }  // namespace net