net/quic/quic_session.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_session.h"
   6
   7 #include "base/stl_util.h"
   8 #include "net/quic/crypto/proof_verifier.h"
   9 #include "net/quic/quic_connection.h"
  10 #include "net/quic/quic_flow_controller.h"
  11 #include "net/quic/quic_headers_stream.h"
  12 #include "net/ssl/ssl_info.h"
  13
  14 using base::StringPiece;
  15 using base::hash_map;
  16 using base::hash_set;
  17 using std::make_pair;
  18 using std::map;
  19 using std::max;
  20 using std::string;
  21 using std::vector;
  22
  23 namespace net {
  24
  25 #define ENDPOINT \
  26   (perspective() == Perspective::IS_SERVER ? "Server: " : " Client: ")
  27
  28 // We want to make sure we delete any closed streams in a safe manner.
  29 // To avoid deleting a stream in mid-operation, we have a simple shim between
  30 // us and the stream, so we can delete any streams when we return from
  31 // processing.
  32 //
  33 // We could just override the base methods, but this makes it easier to make
  34 // sure we don't miss any.
  35 class VisitorShim : public QuicConnectionVisitorInterface {
  36  public:
  37   explicit VisitorShim(QuicSession* session) : session_(session) {}
  38
  39   void OnStreamFrames(const vector<QuicStreamFrame>& frames) override {
  40     session_->OnStreamFrames(frames);
  41     session_->PostProcessAfterData();
  42   }
  43   void OnRstStream(const QuicRstStreamFrame& frame) override {
  44     session_->OnRstStream(frame);
  45     session_->PostProcessAfterData();
  46   }
  47
  48   void OnGoAway(const QuicGoAwayFrame& frame) override {
  49     session_->OnGoAway(frame);
  50     session_->PostProcessAfterData();
  51   }
  52
  53   void OnWindowUpdateFrames(
  54       const vector<QuicWindowUpdateFrame>& frames) override {
  55     session_->OnWindowUpdateFrames(frames);
  56     session_->PostProcessAfterData();
  57   }
  58
  59   void OnBlockedFrames(const vector<QuicBlockedFrame>& frames) override {
  60     session_->OnBlockedFrames(frames);
  61     session_->PostProcessAfterData();
  62   }
  63
  64   void OnCanWrite() override {
  65     session_->OnCanWrite();
  66     session_->PostProcessAfterData();
  67   }
  68
  69   void OnCongestionWindowChange(QuicTime now) override {
  70     session_->OnCongestionWindowChange(now);
  71   }
  72
  73   void OnSuccessfulVersionNegotiation(const QuicVersion& version) override {
  74     session_->OnSuccessfulVersionNegotiation(version);
  75   }
  76
  77   void OnConnectionClosed(QuicErrorCode error, bool from_peer) override {
  78     session_->OnConnectionClosed(error, from_peer);
  79     // The session will go away, so don't bother with cleanup.
  80   }
  81
  82   void OnWriteBlocked() override { session_->OnWriteBlocked(); }
  83
  84   bool WillingAndAbleToWrite() const override {
  85     return session_->WillingAndAbleToWrite();
  86   }
  87
  88   bool HasPendingHandshake() const override {
  89     return session_->HasPendingHandshake();
  90   }
  91
  92   bool HasOpenDataStreams() const override {
  93     return session_->HasOpenDataStreams();
  94   }
  95
  96  private:
  97   QuicSession* session_;
  98 };
  99
 100 QuicSession::QuicSession(QuicConnection* connection, const QuicConfig& config)
 101     : connection_(connection),
 102       visitor_shim_(new VisitorShim(this)),
 103       config_(config),
 104       max_open_streams_(config_.MaxStreamsPerConnection()),
 105       next_stream_id_(perspective() == Perspective::IS_SERVER ? 2 : 5),
 106       largest_peer_created_stream_id_(0),
 107       error_(QUIC_NO_ERROR),
 108       flow_controller_(connection_.get(),
 109                        0,
 110                        perspective(),
 111                        kMinimumFlowControlSendWindow,
 112                        config_.GetInitialSessionFlowControlWindowToSend(),
 113                        false),
 114       goaway_received_(false),
 115       goaway_sent_(false),
 116       has_pending_handshake_(false) {
 117 }
 118
 119 void QuicSession::Initialize() {
 120   // Crypto stream must exist when Initialize is called.
 121   DCHECK(GetCryptoStream());
 122
 123   connection_->set_visitor(visitor_shim_.get());
 124   connection_->SetFromConfig(config_);
 125   headers_stream_.reset(new QuicHeadersStream(this));
 126 }
 127
 128 QuicSession::~QuicSession() {
 129   STLDeleteElements(&closed_streams_);
 130   STLDeleteValues(&stream_map_);
 131
 132   DLOG_IF(WARNING,
 133           locally_closed_streams_highest_offset_.size() > max_open_streams_)
 134       << "Surprisingly high number of locally closed streams still waiting for "
 135          "final byte offset: " << locally_closed_streams_highest_offset_.size();
 136 }
 137
 138 void QuicSession::OnStreamFrames(const vector<QuicStreamFrame>& frames) {
 139   for (size_t i = 0; i < frames.size() && connection_->connected(); ++i) {
 140     // TODO(rch) deal with the error case of stream id 0.
 141     const QuicStreamFrame& frame = frames[i];
 142     QuicStreamId stream_id = frame.stream_id;
 143     ReliableQuicStream* stream = GetStream(stream_id);
 144     if (!stream) {
 145       // The stream no longer exists, but we may still be interested in the
 146       // final stream byte offset sent by the peer. A frame with a FIN can give
 147       // us this offset.
 148       if (frame.fin) {
 149         QuicStreamOffset final_byte_offset = frame.offset + frame.data.size();
 150         UpdateFlowControlOnFinalReceivedByteOffset(stream_id,
 151                                                    final_byte_offset);
 152       }
 153
 154       continue;
 155     }
 156     stream->OnStreamFrame(frames[i]);
 157   }
 158 }
 159
 160 void QuicSession::OnStreamHeaders(QuicStreamId stream_id,
 161                                   StringPiece headers_data) {
 162   QuicDataStream* stream = GetDataStream(stream_id);
 163   if (!stream) {
 164     // It's quite possible to receive headers after a stream has been reset.
 165     return;
 166   }
 167   stream->OnStreamHeaders(headers_data);
 168 }
 169
 170 void QuicSession::OnStreamHeadersPriority(QuicStreamId stream_id,
 171                                           QuicPriority priority) {
 172   QuicDataStream* stream = GetDataStream(stream_id);
 173   if (!stream) {
 174     // It's quite possible to receive headers after a stream has been reset.
 175     return;
 176   }
 177   stream->OnStreamHeadersPriority(priority);
 178 }
 179
 180 void QuicSession::OnStreamHeadersComplete(QuicStreamId stream_id,
 181                                           bool fin,
 182                                           size_t frame_len) {
 183   QuicDataStream* stream = GetDataStream(stream_id);
 184   if (!stream) {
 185     // It's quite possible to receive headers after a stream has been reset.
 186     return;
 187   }
 188   stream->OnStreamHeadersComplete(fin, frame_len);
 189 }
 190
 191 void QuicSession::OnRstStream(const QuicRstStreamFrame& frame) {
 192   if (frame.stream_id == kCryptoStreamId) {
 193     connection()->SendConnectionCloseWithDetails(
 194         QUIC_INVALID_STREAM_ID,
 195         "Attempt to reset the crypto stream");
 196     return;
 197   }
 198   if (frame.stream_id == kHeadersStreamId) {
 199     connection()->SendConnectionCloseWithDetails(
 200         QUIC_INVALID_STREAM_ID,
 201         "Attempt to reset the headers stream");
 202     return;
 203   }
 204
 205   QuicDataStream* stream = GetDataStream(frame.stream_id);
 206   if (!stream) {
 207     // The RST frame contains the final byte offset for the stream: we can now
 208     // update the connection level flow controller if needed.
 209     UpdateFlowControlOnFinalReceivedByteOffset(frame.stream_id,
 210                                                frame.byte_offset);
 211     return;  // Errors are handled by GetStream.
 212   }
 213
 214   stream->OnStreamReset(frame);
 215 }
 216
 217 void QuicSession::OnGoAway(const QuicGoAwayFrame& frame) {
 218   DCHECK(frame.last_good_stream_id < next_stream_id_);
 219   goaway_received_ = true;
 220 }
 221
 222 void QuicSession::OnConnectionClosed(QuicErrorCode error, bool from_peer) {
 223   DCHECK(!connection_->connected());
 224   if (error_ == QUIC_NO_ERROR) {
 225     error_ = error;
 226   }
 227
 228   while (!stream_map_.empty()) {
 229     DataStreamMap::iterator it = stream_map_.begin();
 230     QuicStreamId id = it->first;
 231     it->second->OnConnectionClosed(error, from_peer);
 232     // The stream should call CloseStream as part of OnConnectionClosed.
 233     if (stream_map_.find(id) != stream_map_.end()) {
 234       LOG(DFATAL) << ENDPOINT
 235                   << "Stream failed to close under OnConnectionClosed";
 236       CloseStream(id);
 237     }
 238   }
 239 }
 240
 241 void QuicSession::OnSuccessfulVersionNegotiation(const QuicVersion& version) {
 242 }
 243
 244 void QuicSession::OnWindowUpdateFrames(
 245     const vector<QuicWindowUpdateFrame>& frames) {
 246   bool connection_window_updated = false;
 247   for (size_t i = 0; i < frames.size(); ++i) {
 248     // Stream may be closed by the time we receive a WINDOW_UPDATE, so we can't
 249     // assume that it still exists.
 250     QuicStreamId stream_id = frames[i].stream_id;
 251     if (stream_id == kConnectionLevelId) {
 252       // This is a window update that applies to the connection, rather than an
 253       // individual stream.
 254       DVLOG(1) << ENDPOINT
 255                << "Received connection level flow control window update with "
 256                   "byte offset: " << frames[i].byte_offset;
 257       if (flow_controller_.UpdateSendWindowOffset(frames[i].byte_offset)) {
 258         connection_window_updated = true;
 259       }
 260       continue;
 261     }
 262
 263     ReliableQuicStream* stream = GetStream(stream_id);
 264     if (stream) {
 265       stream->OnWindowUpdateFrame(frames[i]);
 266     }
 267   }
 268
 269   // Connection level flow control window has increased, so blocked streams can
 270   // write again.
 271   if (connection_window_updated) {
 272     OnCanWrite();
 273   }
 274 }
 275
 276 void QuicSession::OnBlockedFrames(const vector<QuicBlockedFrame>& frames) {
 277   for (size_t i = 0; i < frames.size(); ++i) {
 278     // TODO(rjshade): Compare our flow control receive windows for specified
 279     //                streams: if we have a large window then maybe something
 280     //                had gone wrong with the flow control accounting.
 281     DVLOG(1) << ENDPOINT << "Received BLOCKED frame with stream id: "
 282              << frames[i].stream_id;
 283   }
 284 }
 285
 286 void QuicSession::OnCanWrite() {
 287   // We limit the number of writes to the number of pending streams. If more
 288   // streams become pending, WillingAndAbleToWrite will be true, which will
 289   // cause the connection to request resumption before yielding to other
 290   // connections.
 291   size_t num_writes = write_blocked_streams_.NumBlockedStreams();
 292   if (flow_controller_.IsBlocked()) {
 293     // If we are connection level flow control blocked, then only allow the
 294     // crypto and headers streams to try writing as all other streams will be
 295     // blocked.
 296     num_writes = 0;
 297     if (write_blocked_streams_.crypto_stream_blocked()) {
 298       num_writes += 1;
 299     }
 300     if (write_blocked_streams_.headers_stream_blocked()) {
 301       num_writes += 1;
 302     }
 303   }
 304   if (num_writes == 0) {
 305     return;
 306   }
 307
 308   QuicConnection::ScopedPacketBundler ack_bundler(
 309       connection_.get(), QuicConnection::NO_ACK);
 310   for (size_t i = 0; i < num_writes; ++i) {
 311     if (!(write_blocked_streams_.HasWriteBlockedCryptoOrHeadersStream() ||
 312           write_blocked_streams_.HasWriteBlockedDataStreams())) {
 313       // Writing one stream removed another!? Something's broken.
 314       LOG(DFATAL) << "WriteBlockedStream is missing";
 315       connection_->CloseConnection(QUIC_INTERNAL_ERROR, false);
 316       return;
 317     }
 318     if (!connection_->CanWriteStreamData()) {
 319       return;
 320     }
 321     QuicStreamId stream_id = write_blocked_streams_.PopFront();
 322     if (stream_id == kCryptoStreamId) {
 323       has_pending_handshake_ = false;  // We just popped it.
 324     }
 325     ReliableQuicStream* stream = GetStream(stream_id);
 326     if (stream != nullptr && !stream->flow_controller()->IsBlocked()) {
 327       // If the stream can't write all bytes, it'll re-add itself to the blocked
 328       // list.
 329       stream->OnCanWrite();
 330     }
 331   }
 332 }
 333
 334 bool QuicSession::WillingAndAbleToWrite() const {
 335   // If the crypto or headers streams are blocked, we want to schedule a write -
 336   // they don't get blocked by connection level flow control. Otherwise only
 337   // schedule a write if we are not flow control blocked at the connection
 338   // level.
 339   return write_blocked_streams_.HasWriteBlockedCryptoOrHeadersStream() ||
 340          (!flow_controller_.IsBlocked() &&
 341           write_blocked_streams_.HasWriteBlockedDataStreams());
 342 }
 343
 344 bool QuicSession::HasPendingHandshake() const {
 345   return has_pending_handshake_;
 346 }
 347
 348 bool QuicSession::HasOpenDataStreams() const {
 349   return GetNumOpenStreams() > 0;
 350 }
 351
 352 QuicConsumedData QuicSession::WritevData(
 353     QuicStreamId id,
 354     const IOVector& data,
 355     QuicStreamOffset offset,
 356     bool fin,
 357     FecProtection fec_protection,
 358     QuicAckNotifier::DelegateInterface* ack_notifier_delegate) {
 359   return connection_->SendStreamData(id, data, offset, fin, fec_protection,
 360                                      ack_notifier_delegate);
 361 }
 362
 363 size_t QuicSession::WriteHeaders(
 364     QuicStreamId id,
 365     const SpdyHeaderBlock& headers,
 366     bool fin,
 367     QuicPriority priority,
 368     QuicAckNotifier::DelegateInterface* ack_notifier_delegate) {
 369   return headers_stream_->WriteHeaders(id, headers, fin, priority,
 370                                        ack_notifier_delegate);
 371 }
 372
 373 void QuicSession::SendRstStream(QuicStreamId id,
 374                                 QuicRstStreamErrorCode error,
 375                                 QuicStreamOffset bytes_written) {
 376   if (connection()->connected()) {
 377     // Only send a RST_STREAM frame if still connected.
 378     connection_->SendRstStream(id, error, bytes_written);
 379   }
 380   CloseStreamInner(id, true);
 381 }
 382
 383 void QuicSession::SendGoAway(QuicErrorCode error_code, const string& reason) {
 384   if (goaway_sent_) {
 385     return;
 386   }
 387   goaway_sent_ = true;
 388   connection_->SendGoAway(error_code, largest_peer_created_stream_id_, reason);
 389 }
 390
 391 void QuicSession::CloseStream(QuicStreamId stream_id) {
 392   CloseStreamInner(stream_id, false);
 393 }
 394
 395 void QuicSession::CloseStreamInner(QuicStreamId stream_id,
 396                                    bool locally_reset) {
 397   DVLOG(1) << ENDPOINT << "Closing stream " << stream_id;
 398
 399   DataStreamMap::iterator it = stream_map_.find(stream_id);
 400   if (it == stream_map_.end()) {
 401     DVLOG(1) << ENDPOINT << "Stream is already closed: " << stream_id;
 402     return;
 403   }
 404   QuicDataStream* stream = it->second;
 405
 406   // Tell the stream that a RST has been sent.
 407   if (locally_reset) {
 408     stream->set_rst_sent(true);
 409   }
 410
 411   closed_streams_.push_back(it->second);
 412
 413   // If we haven't received a FIN or RST for this stream, we need to keep track
 414   // of the how many bytes the stream's flow controller believes it has
 415   // received, for accurate connection level flow control accounting.
 416   if (!stream->HasFinalReceivedByteOffset()) {
 417     locally_closed_streams_highest_offset_[stream_id] =
 418         stream->flow_controller()->highest_received_byte_offset();
 419   }
 420
 421   stream_map_.erase(it);
 422   stream->OnClose();
 423   // Decrease the number of streams being emulated when a new one is opened.
 424   connection_->SetNumOpenStreams(stream_map_.size());
 425 }
 426
 427 void QuicSession::UpdateFlowControlOnFinalReceivedByteOffset(
 428     QuicStreamId stream_id, QuicStreamOffset final_byte_offset) {
 429   map<QuicStreamId, QuicStreamOffset>::iterator it =
 430       locally_closed_streams_highest_offset_.find(stream_id);
 431   if (it == locally_closed_streams_highest_offset_.end()) {
 432     return;
 433   }
 434
 435   DVLOG(1) << ENDPOINT << "Received final byte offset " << final_byte_offset
 436            << " for stream " << stream_id;
 437   QuicByteCount offset_diff = final_byte_offset - it->second;
 438   if (flow_controller_.UpdateHighestReceivedOffset(
 439           flow_controller_.highest_received_byte_offset() + offset_diff)) {
 440     // If the final offset violates flow control, close the connection now.
 441     if (flow_controller_.FlowControlViolation()) {
 442       connection_->SendConnectionClose(
 443           QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA);
 444       return;
 445     }
 446   }
 447
 448   flow_controller_.AddBytesConsumed(offset_diff);
 449   locally_closed_streams_highest_offset_.erase(it);
 450 }
 451
 452 bool QuicSession::IsEncryptionEstablished() {
 453   return GetCryptoStream()->encryption_established();
 454 }
 455
 456 bool QuicSession::IsCryptoHandshakeConfirmed() {
 457   return GetCryptoStream()->handshake_confirmed();
 458 }
 459
 460 void QuicSession::OnConfigNegotiated() {
 461   connection_->SetFromConfig(config_);
 462
 463   uint32 max_streams = config_.MaxStreamsPerConnection();
 464   if (perspective() == Perspective::IS_SERVER) {
 465     // A server should accept a small number of additional streams beyond the
 466     // limit sent to the client. This helps avoid early connection termination
 467     // when FIN/RSTs for old streams are lost or arrive out of order.
 468     // Use a minimum number of additional streams, or a percentage increase,
 469     // whichever is larger.
 470     max_streams =
 471         max(max_streams + kMaxStreamsMinimumIncrement,
 472             static_cast<uint32>(max_streams * kMaxStreamsMultiplier));
 473
 474     if (config_.HasReceivedConnectionOptions() &&
 475         ContainsQuicTag(config_.ReceivedConnectionOptions(), kAFCW)) {
 476       EnableAutoTuneReceiveWindow();
 477     }
 478   }
 479   set_max_open_streams(max_streams);
 480
 481   if (config_.HasReceivedInitialStreamFlowControlWindowBytes()) {
 482     // Streams which were created before the SHLO was received (0-RTT
 483     // requests) are now informed of the peer's initial flow control window.
 484     OnNewStreamFlowControlWindow(
 485         config_.ReceivedInitialStreamFlowControlWindowBytes());
 486   }
 487   if (config_.HasReceivedInitialSessionFlowControlWindowBytes()) {
 488     OnNewSessionFlowControlWindow(
 489         config_.ReceivedInitialSessionFlowControlWindowBytes());
 490   }
 491 }
 492
 493 void QuicSession::EnableAutoTuneReceiveWindow() {
 494   flow_controller_.set_auto_tune_receive_window(true);
 495   // Inform all existing streams about the new window.
 496   GetCryptoStream()->flow_controller()->set_auto_tune_receive_window(true);
 497   headers_stream_->flow_controller()->set_auto_tune_receive_window(true);
 498   for (auto const& kv : stream_map_) {
 499     kv.second->flow_controller()->set_auto_tune_receive_window(true);
 500   }
 501 }
 502
 503 void QuicSession::OnNewStreamFlowControlWindow(QuicStreamOffset new_window) {
 504   if (new_window < kMinimumFlowControlSendWindow) {
 505     LOG(ERROR) << "Peer sent us an invalid stream flow control send window: "
 506                << new_window
 507                << ", below default: " << kMinimumFlowControlSendWindow;
 508     if (connection_->connected()) {
 509       connection_->SendConnectionClose(QUIC_FLOW_CONTROL_INVALID_WINDOW);
 510     }
 511     return;
 512   }
 513
 514   // Inform all existing streams about the new window.
 515   GetCryptoStream()->UpdateSendWindowOffset(new_window);
 516   headers_stream_->UpdateSendWindowOffset(new_window);
 517   for (auto const& kv : stream_map_) {
 518     kv.second->UpdateSendWindowOffset(new_window);
 519   }
 520 }
 521
 522 void QuicSession::OnNewSessionFlowControlWindow(QuicStreamOffset new_window) {
 523   if (new_window < kMinimumFlowControlSendWindow) {
 524     LOG(ERROR) << "Peer sent us an invalid session flow control send window: "
 525                << new_window
 526                << ", below default: " << kMinimumFlowControlSendWindow;
 527     if (connection_->connected()) {
 528       connection_->SendConnectionClose(QUIC_FLOW_CONTROL_INVALID_WINDOW);
 529     }
 530     return;
 531   }
 532
 533   flow_controller_.UpdateSendWindowOffset(new_window);
 534 }
 535
 536 void QuicSession::OnCryptoHandshakeEvent(CryptoHandshakeEvent event) {
 537   switch (event) {
 538     // TODO(satyamshekhar): Move the logic of setting the encrypter/decrypter
 539     // to QuicSession since it is the glue.
 540     case ENCRYPTION_FIRST_ESTABLISHED:
 541       break;
 542
 543     case ENCRYPTION_REESTABLISHED:
 544       // Retransmit originally packets that were sent, since they can't be
 545       // decrypted by the peer.
 546       connection_->RetransmitUnackedPackets(ALL_INITIAL_RETRANSMISSION);
 547       break;
 548
 549     case HANDSHAKE_CONFIRMED:
 550       LOG_IF(DFATAL, !config_.negotiated()) << ENDPOINT
 551           << "Handshake confirmed without parameter negotiation.";
 552       // Discard originally encrypted packets, since they can't be decrypted by
 553       // the peer.
 554       connection_->NeuterUnencryptedPackets();
 555       break;
 556
 557     default:
 558       LOG(ERROR) << ENDPOINT << "Got unknown handshake event: " << event;
 559   }
 560 }
 561
 562 void QuicSession::OnCryptoHandshakeMessageSent(
 563     const CryptoHandshakeMessage& message) {
 564 }
 565
 566 void QuicSession::OnCryptoHandshakeMessageReceived(
 567     const CryptoHandshakeMessage& message) {
 568 }
 569
 570 QuicConfig* QuicSession::config() {
 571   return &config_;
 572 }
 573
 574 void QuicSession::ActivateStream(QuicDataStream* stream) {
 575   DVLOG(1) << ENDPOINT << "num_streams: " << stream_map_.size()
 576            << ". activating " << stream->id();
 577   DCHECK_EQ(stream_map_.count(stream->id()), 0u);
 578   stream_map_[stream->id()] = stream;
 579   // Increase the number of streams being emulated when a new one is opened.
 580   connection_->SetNumOpenStreams(stream_map_.size());
 581 }
 582
 583 QuicStreamId QuicSession::GetNextStreamId() {
 584   QuicStreamId id = next_stream_id_;
 585   next_stream_id_ += 2;
 586   return id;
 587 }
 588
 589 ReliableQuicStream* QuicSession::GetStream(const QuicStreamId stream_id) {
 590   if (stream_id == kCryptoStreamId) {
 591     return GetCryptoStream();
 592   }
 593   if (stream_id == kHeadersStreamId) {
 594     return headers_stream_.get();
 595   }
 596   return GetDataStream(stream_id);
 597 }
 598
 599 QuicDataStream* QuicSession::GetDataStream(const QuicStreamId stream_id) {
 600   if (stream_id == kCryptoStreamId) {
 601     DLOG(FATAL) << "Attempt to call GetDataStream with the crypto stream id";
 602     return nullptr;
 603   }
 604   if (stream_id == kHeadersStreamId) {
 605     DLOG(FATAL) << "Attempt to call GetDataStream with the headers stream id";
 606     return nullptr;
 607   }
 608
 609   DataStreamMap::iterator it = stream_map_.find(stream_id);
 610   if (it != stream_map_.end()) {
 611     return it->second;
 612   }
 613
 614   if (IsClosedStream(stream_id)) {
 615     return nullptr;
 616   }
 617
 618   if (stream_id % 2 == next_stream_id_ % 2) {
 619     // We've received a frame for a locally-created stream that is not
 620     // currently active.  This is an error.
 621     if (connection()->connected()) {
 622       connection()->SendConnectionClose(QUIC_PACKET_FOR_NONEXISTENT_STREAM);
 623     }
 624     return nullptr;
 625   }
 626
 627   return GetIncomingDataStream(stream_id);
 628 }
 629
 630 QuicDataStream* QuicSession::GetIncomingDataStream(QuicStreamId stream_id) {
 631   if (IsClosedStream(stream_id)) {
 632     return nullptr;
 633   }
 634
 635   implicitly_created_streams_.erase(stream_id);
 636   if (stream_id > largest_peer_created_stream_id_) {
 637     if (stream_id - largest_peer_created_stream_id_ > kMaxStreamIdDelta) {
 638       // We may already have sent a connection close due to multiple reset
 639       // streams in the same packet.
 640       if (connection()->connected()) {
 641         LOG(ERROR) << "Trying to get stream: " << stream_id
 642                    << ", largest peer created stream: "
 643                    << largest_peer_created_stream_id_
 644                    << ", max delta: " << kMaxStreamIdDelta;
 645         connection()->SendConnectionClose(QUIC_INVALID_STREAM_ID);
 646       }
 647       return nullptr;
 648     }
 649     if (largest_peer_created_stream_id_ == 0 &&
 650         perspective() == Perspective::IS_SERVER) {
 651       largest_peer_created_stream_id_ = 3;
 652     }
 653     for (QuicStreamId id = largest_peer_created_stream_id_ + 2;
 654          id < stream_id;
 655          id += 2) {
 656       implicitly_created_streams_.insert(id);
 657     }
 658     largest_peer_created_stream_id_ = stream_id;
 659   }
 660   QuicDataStream* stream = CreateIncomingDataStream(stream_id);
 661   if (stream == nullptr) {
 662     return nullptr;
 663   }
 664   ActivateStream(stream);
 665   return stream;
 666 }
 667
 668 void QuicSession::set_max_open_streams(size_t max_open_streams) {
 669   DVLOG(1) << "Setting max_open_streams_ to " << max_open_streams;
 670   max_open_streams_ = max_open_streams;
 671 }
 672
 673 bool QuicSession::IsClosedStream(QuicStreamId id) {
 674   DCHECK_NE(0u, id);
 675   if (id == kCryptoStreamId) {
 676     return false;
 677   }
 678   if (id == kHeadersStreamId) {
 679     return false;
 680   }
 681   if (ContainsKey(stream_map_, id)) {
 682     // Stream is active
 683     return false;
 684   }
 685   if (id % 2 == next_stream_id_ % 2) {
 686     // Locally created streams are strictly in-order.  If the id is in the
 687     // range of created streams and it's not active, it must have been closed.
 688     return id < next_stream_id_;
 689   }
 690   // For peer created streams, we also need to consider implicitly created
 691   // streams.
 692   return id <= largest_peer_created_stream_id_ &&
 693       !ContainsKey(implicitly_created_streams_, id);
 694 }
 695
 696 size_t QuicSession::GetNumOpenStreams() const {
 697   return stream_map_.size() + implicitly_created_streams_.size();
 698 }
 699
 700 void QuicSession::MarkWriteBlocked(QuicStreamId id, QuicPriority priority) {
 701 #ifndef NDEBUG
 702   ReliableQuicStream* stream = GetStream(id);
 703   if (stream != nullptr) {
 704     LOG_IF(DFATAL, priority != stream->EffectivePriority())
 705         << ENDPOINT << "Stream " << id
 706         << "Priorities do not match.  Got: " << priority
 707         << " Expected: " << stream->EffectivePriority();
 708   } else {
 709     LOG(DFATAL) << "Marking unknown stream " << id << " blocked.";
 710   }
 711 #endif
 712
 713   if (id == kCryptoStreamId) {
 714     DCHECK(!has_pending_handshake_);
 715     has_pending_handshake_ = true;
 716     // TODO(jar): Be sure to use the highest priority for the crypto stream,
 717     // perhaps by adding a "special" priority for it that is higher than
 718     // kHighestPriority.
 719     priority = kHighestPriority;
 720   }
 721   write_blocked_streams_.PushBack(id, priority);
 722 }
 723
 724 bool QuicSession::HasDataToWrite() const {
 725   return write_blocked_streams_.HasWriteBlockedCryptoOrHeadersStream() ||
 726          write_blocked_streams_.HasWriteBlockedDataStreams() ||
 727          connection_->HasQueuedData();
 728 }
 729
 730 void QuicSession::PostProcessAfterData() {
 731   STLDeleteElements(&closed_streams_);
 732
 733   if (connection()->connected() &&
 734       locally_closed_streams_highest_offset_.size() > max_open_streams_) {
 735     // A buggy client may fail to send FIN/RSTs. Don't tolerate this.
 736     connection_->SendConnectionClose(QUIC_TOO_MANY_UNFINISHED_STREAMS);
 737   }
 738 }
 739
 740 bool QuicSession::IsConnectionFlowControlBlocked() const {
 741   return flow_controller_.IsBlocked();
 742 }
 743
 744 bool QuicSession::IsStreamFlowControlBlocked() {
 745   if (headers_stream_->flow_controller()->IsBlocked() ||
 746       GetCryptoStream()->flow_controller()->IsBlocked()) {
 747     return true;
 748   }
 749   for (auto const& kv : stream_map_) {
 750     if (kv.second->flow_controller()->IsBlocked()) {
 751       return true;
 752     }
 753   }
 754   return false;
 755 }
 756
 757 }  // namespace net