1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "net/quic/quic_connection.h"
6
7#include <string.h>
8#include <sys/types.h>
9#include <algorithm>
10#include <iterator>
11#include <limits>
12#include <memory>
13#include <set>
14#include <utility>
15
16#include "base/debug/stack_trace.h"
17#include "base/logging.h"
18#include "base/stl_util.h"
19#include "net/base/net_errors.h"
20#include "net/quic/crypto/quic_decrypter.h"
21#include "net/quic/crypto/quic_encrypter.h"
22#include "net/quic/iovector.h"
23#include "net/quic/quic_bandwidth.h"
24#include "net/quic/quic_config.h"
25#include "net/quic/quic_flags.h"
26#include "net/quic/quic_utils.h"
27
28using base::StringPiece;
29using base::hash_map;
30using base::hash_set;
31using std::list;
32using std::make_pair;
33using std::max;
34using std::min;
35using std::numeric_limits;
36using std::set;
37using std::string;
38using std::vector;
39
40namespace net {
41
42class QuicDecrypter;
43class QuicEncrypter;
44
45namespace {
46
47// The largest gap in packets we'll accept without closing the connection.
48// This will likely have to be tuned.
49const QuicPacketSequenceNumber kMaxPacketGap = 5000;
50
51// Limit the number of FEC groups to two.  If we get enough out of order packets
52// that this becomes limiting, we can revisit.
53const size_t kMaxFecGroups = 2;
54
55// Limit the number of undecryptable packets we buffer in
56// expectation of the CHLO/SHLO arriving.
57const size_t kMaxUndecryptablePackets = 10;
58
59bool Near(QuicPacketSequenceNumber a, QuicPacketSequenceNumber b) {
60  QuicPacketSequenceNumber delta = (a > b) ? a - b : b - a;
61  return delta <= kMaxPacketGap;
62}
63
64// An alarm that is scheduled to send an ack if a timeout occurs.
65class AckAlarm : public QuicAlarm::Delegate {
66 public:
67  explicit AckAlarm(QuicConnection* connection)
68      : connection_(connection) {
69  }
70
71  virtual QuicTime OnAlarm() OVERRIDE {
72    connection_->SendAck();
73    return QuicTime::Zero();
74  }
75
76 private:
77  QuicConnection* connection_;
78
79  DISALLOW_COPY_AND_ASSIGN(AckAlarm);
80};
81
82// This alarm will be scheduled any time a data-bearing packet is sent out.
83// When the alarm goes off, the connection checks to see if the oldest packets
84// have been acked, and retransmit them if they have not.
85class RetransmissionAlarm : public QuicAlarm::Delegate {
86 public:
87  explicit RetransmissionAlarm(QuicConnection* connection)
88      : connection_(connection) {
89  }
90
91  virtual QuicTime OnAlarm() OVERRIDE {
92    connection_->OnRetransmissionTimeout();
93    return QuicTime::Zero();
94  }
95
96 private:
97  QuicConnection* connection_;
98
99  DISALLOW_COPY_AND_ASSIGN(RetransmissionAlarm);
100};
101
102// An alarm that is scheduled when the sent scheduler requires a
103// a delay before sending packets and fires when the packet may be sent.
104class SendAlarm : public QuicAlarm::Delegate {
105 public:
106  explicit SendAlarm(QuicConnection* connection)
107      : connection_(connection) {
108  }
109
110  virtual QuicTime OnAlarm() OVERRIDE {
111    connection_->WriteIfNotBlocked();
112    // Never reschedule the alarm, since CanWrite does that.
113    return QuicTime::Zero();
114  }
115
116 private:
117  QuicConnection* connection_;
118
119  DISALLOW_COPY_AND_ASSIGN(SendAlarm);
120};
121
122class TimeoutAlarm : public QuicAlarm::Delegate {
123 public:
124  explicit TimeoutAlarm(QuicConnection* connection)
125      : connection_(connection) {
126  }
127
128  virtual QuicTime OnAlarm() OVERRIDE {
129    connection_->CheckForTimeout();
130    // Never reschedule the alarm, since CheckForTimeout does that.
131    return QuicTime::Zero();
132  }
133
134 private:
135  QuicConnection* connection_;
136
137  DISALLOW_COPY_AND_ASSIGN(TimeoutAlarm);
138};
139
140class PingAlarm : public QuicAlarm::Delegate {
141 public:
142  explicit PingAlarm(QuicConnection* connection)
143      : connection_(connection) {
144  }
145
146  virtual QuicTime OnAlarm() OVERRIDE {
147    connection_->SendPing();
148    return QuicTime::Zero();
149  }
150
151 private:
152  QuicConnection* connection_;
153
154  DISALLOW_COPY_AND_ASSIGN(PingAlarm);
155};
156
157QuicConnection::PacketType GetPacketType(
158    const RetransmittableFrames* retransmittable_frames) {
159  if (!retransmittable_frames) {
160    return QuicConnection::NORMAL;
161  }
162  for (size_t i = 0; i < retransmittable_frames->frames().size(); ++i) {
163    if (retransmittable_frames->frames()[i].type == CONNECTION_CLOSE_FRAME) {
164      return QuicConnection::CONNECTION_CLOSE;
165    }
166  }
167  return QuicConnection::NORMAL;
168}
169
170}  // namespace
171
172QuicConnection::QueuedPacket::QueuedPacket(SerializedPacket packet,
173                                           EncryptionLevel level,
174                                           TransmissionType transmission_type)
175  : sequence_number(packet.sequence_number),
176    packet(packet.packet),
177    encryption_level(level),
178    transmission_type(transmission_type),
179    retransmittable((transmission_type != NOT_RETRANSMISSION ||
180                     packet.retransmittable_frames != NULL) ?
181                         HAS_RETRANSMITTABLE_DATA : NO_RETRANSMITTABLE_DATA),
182    handshake(packet.retransmittable_frames == NULL ?
183      NOT_HANDSHAKE : packet.retransmittable_frames->HasCryptoHandshake()),
184    type(GetPacketType(packet.retransmittable_frames)),
185    length(packet.packet->length()) {
186}
187
188#define ENDPOINT (is_server_ ? "Server: " : " Client: ")
189
190QuicConnection::QuicConnection(QuicConnectionId connection_id,
191                               IPEndPoint address,
192                               QuicConnectionHelperInterface* helper,
193                               QuicPacketWriter* writer,
194                               bool is_server,
195                               const QuicVersionVector& supported_versions)
196    : framer_(supported_versions, helper->GetClock()->ApproximateNow(),
197              is_server),
198      helper_(helper),
199      writer_(writer),
200      encryption_level_(ENCRYPTION_NONE),
201      clock_(helper->GetClock()),
202      random_generator_(helper->GetRandomGenerator()),
203      connection_id_(connection_id),
204      peer_address_(address),
205      migrating_peer_port_(0),
206      last_packet_revived_(false),
207      last_size_(0),
208      last_decrypted_packet_level_(ENCRYPTION_NONE),
209      largest_seen_packet_with_ack_(0),
210      largest_seen_packet_with_stop_waiting_(0),
211      pending_version_negotiation_packet_(false),
212      received_packet_manager_(kTCP, &stats_),
213      ack_queued_(false),
214      stop_waiting_count_(0),
215      ack_alarm_(helper->CreateAlarm(new AckAlarm(this))),
216      retransmission_alarm_(helper->CreateAlarm(new RetransmissionAlarm(this))),
217      send_alarm_(helper->CreateAlarm(new SendAlarm(this))),
218      resume_writes_alarm_(helper->CreateAlarm(new SendAlarm(this))),
219      timeout_alarm_(helper->CreateAlarm(new TimeoutAlarm(this))),
220      ping_alarm_(helper->CreateAlarm(new PingAlarm(this))),
221      debug_visitor_(NULL),
222      packet_generator_(connection_id_, &framer_, random_generator_, this),
223      idle_network_timeout_(
224          QuicTime::Delta::FromSeconds(kDefaultInitialTimeoutSecs)),
225      overall_connection_timeout_(QuicTime::Delta::Infinite()),
226      time_of_last_received_packet_(clock_->ApproximateNow()),
227      time_of_last_sent_new_packet_(clock_->ApproximateNow()),
228      sequence_number_of_last_sent_packet_(0),
229      sent_packet_manager_(
230          is_server, clock_, &stats_, kTCP,
231          FLAGS_quic_use_time_loss_detection ? kTime : kNack),
232      version_negotiation_state_(START_NEGOTIATION),
233      is_server_(is_server),
234      connected_(true),
235      peer_ip_changed_(false),
236      peer_port_changed_(false),
237      self_ip_changed_(false),
238      self_port_changed_(false) {
239  if (!is_server_) {
240    // Pacing will be enabled if the client negotiates it.
241    sent_packet_manager_.MaybeEnablePacing();
242  }
243  DVLOG(1) << ENDPOINT << "Created connection with connection_id: "
244           << connection_id;
245  timeout_alarm_->Set(clock_->ApproximateNow().Add(idle_network_timeout_));
246  framer_.set_visitor(this);
247  framer_.set_received_entropy_calculator(&received_packet_manager_);
248  stats_.connection_creation_time = clock_->ApproximateNow();
249}
250
251QuicConnection::~QuicConnection() {
252  STLDeleteElements(&undecryptable_packets_);
253  STLDeleteValues(&group_map_);
254  for (QueuedPacketList::iterator it = queued_packets_.begin();
255       it != queued_packets_.end(); ++it) {
256    delete it->packet;
257  }
258}
259
260void QuicConnection::SetFromConfig(const QuicConfig& config) {
261  SetIdleNetworkTimeout(config.idle_connection_state_lifetime());
262  sent_packet_manager_.SetFromConfig(config);
263  // TODO(satyamshekhar): Set congestion control and ICSL also.
264}
265
266bool QuicConnection::SelectMutualVersion(
267    const QuicVersionVector& available_versions) {
268  // Try to find the highest mutual version by iterating over supported
269  // versions, starting with the highest, and breaking out of the loop once we
270  // find a matching version in the provided available_versions vector.
271  const QuicVersionVector& supported_versions = framer_.supported_versions();
272  for (size_t i = 0; i < supported_versions.size(); ++i) {
273    const QuicVersion& version = supported_versions[i];
274    if (std::find(available_versions.begin(), available_versions.end(),
275                  version) != available_versions.end()) {
276      framer_.set_version(version);
277      return true;
278    }
279  }
280
281  return false;
282}
283
284void QuicConnection::OnError(QuicFramer* framer) {
285  // Packets that we cannot decrypt are dropped.
286  // TODO(rch): add stats to measure this.
287  if (!connected_ || framer->error() == QUIC_DECRYPTION_FAILURE) {
288    return;
289  }
290  SendConnectionCloseWithDetails(framer->error(), framer->detailed_error());
291}
292
293void QuicConnection::OnPacket() {
294  DCHECK(last_stream_frames_.empty() &&
295         last_goaway_frames_.empty() &&
296         last_window_update_frames_.empty() &&
297         last_blocked_frames_.empty() &&
298         last_rst_frames_.empty() &&
299         last_ack_frames_.empty() &&
300         last_congestion_frames_.empty() &&
301         last_stop_waiting_frames_.empty());
302}
303
304void QuicConnection::OnPublicResetPacket(
305    const QuicPublicResetPacket& packet) {
306  if (debug_visitor_) {
307    debug_visitor_->OnPublicResetPacket(packet);
308  }
309  CloseConnection(QUIC_PUBLIC_RESET, true);
310}
311
312bool QuicConnection::OnProtocolVersionMismatch(QuicVersion received_version) {
313  DVLOG(1) << ENDPOINT << "Received packet with mismatched version "
314           << received_version;
315  // TODO(satyamshekhar): Implement no server state in this mode.
316  if (!is_server_) {
317    LOG(DFATAL) << ENDPOINT << "Framer called OnProtocolVersionMismatch. "
318                << "Closing connection.";
319    CloseConnection(QUIC_INTERNAL_ERROR, false);
320    return false;
321  }
322  DCHECK_NE(version(), received_version);
323
324  if (debug_visitor_) {
325    debug_visitor_->OnProtocolVersionMismatch(received_version);
326  }
327
328  switch (version_negotiation_state_) {
329    case START_NEGOTIATION:
330      if (!framer_.IsSupportedVersion(received_version)) {
331        SendVersionNegotiationPacket();
332        version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
333        return false;
334      }
335      break;
336
337    case NEGOTIATION_IN_PROGRESS:
338      if (!framer_.IsSupportedVersion(received_version)) {
339        SendVersionNegotiationPacket();
340        return false;
341      }
342      break;
343
344    case NEGOTIATED_VERSION:
345      // Might be old packets that were sent by the client before the version
346      // was negotiated. Drop these.
347      return false;
348
349    default:
350      DCHECK(false);
351  }
352
353  version_negotiation_state_ = NEGOTIATED_VERSION;
354  visitor_->OnSuccessfulVersionNegotiation(received_version);
355  DVLOG(1) << ENDPOINT << "version negotiated " << received_version;
356
357  // Store the new version.
358  framer_.set_version(received_version);
359
360  // TODO(satyamshekhar): Store the sequence number of this packet and close the
361  // connection if we ever received a packet with incorrect version and whose
362  // sequence number is greater.
363  return true;
364}
365
366// Handles version negotiation for client connection.
367void QuicConnection::OnVersionNegotiationPacket(
368    const QuicVersionNegotiationPacket& packet) {
369  if (is_server_) {
370    LOG(DFATAL) << ENDPOINT << "Framer parsed VersionNegotiationPacket."
371                << " Closing connection.";
372    CloseConnection(QUIC_INTERNAL_ERROR, false);
373    return;
374  }
375  if (debug_visitor_) {
376    debug_visitor_->OnVersionNegotiationPacket(packet);
377  }
378
379  if (version_negotiation_state_ != START_NEGOTIATION) {
380    // Possibly a duplicate version negotiation packet.
381    return;
382  }
383
384  if (std::find(packet.versions.begin(),
385                packet.versions.end(), version()) !=
386      packet.versions.end()) {
387    DLOG(WARNING) << ENDPOINT << "The server already supports our version. "
388                  << "It should have accepted our connection.";
389    // Just drop the connection.
390    CloseConnection(QUIC_INVALID_VERSION_NEGOTIATION_PACKET, false);
391    return;
392  }
393
394  if (!SelectMutualVersion(packet.versions)) {
395    SendConnectionCloseWithDetails(QUIC_INVALID_VERSION,
396                                   "no common version found");
397    return;
398  }
399
400  DVLOG(1) << ENDPOINT << "negotiating version " << version();
401  server_supported_versions_ = packet.versions;
402  version_negotiation_state_ = NEGOTIATION_IN_PROGRESS;
403  RetransmitUnackedPackets(ALL_PACKETS);
404}
405
406void QuicConnection::OnRevivedPacket() {
407}
408
409bool QuicConnection::OnUnauthenticatedPublicHeader(
410    const QuicPacketPublicHeader& header) {
411  return true;
412}
413
414bool QuicConnection::OnUnauthenticatedHeader(const QuicPacketHeader& header) {
415  return true;
416}
417
418void QuicConnection::OnDecryptedPacket(EncryptionLevel level) {
419  last_decrypted_packet_level_ = level;
420}
421
422bool QuicConnection::OnPacketHeader(const QuicPacketHeader& header) {
423  if (debug_visitor_) {
424    debug_visitor_->OnPacketHeader(header);
425  }
426
427  if (!ProcessValidatedPacket()) {
428    return false;
429  }
430
431  // Will be decrement below if we fall through to return true;
432  ++stats_.packets_dropped;
433
434  if (header.public_header.connection_id != connection_id_) {
435    DVLOG(1) << ENDPOINT << "Ignoring packet from unexpected ConnectionId: "
436             << header.public_header.connection_id << " instead of "
437             << connection_id_;
438    return false;
439  }
440
441  if (!Near(header.packet_sequence_number,
442            last_header_.packet_sequence_number)) {
443    DVLOG(1) << ENDPOINT << "Packet " << header.packet_sequence_number
444             << " out of bounds.  Discarding";
445    SendConnectionCloseWithDetails(QUIC_INVALID_PACKET_HEADER,
446                                   "Packet sequence number out of bounds");
447    return false;
448  }
449
450  // If this packet has already been seen, or that the sender
451  // has told us will not be retransmitted, then stop processing the packet.
452  if (!received_packet_manager_.IsAwaitingPacket(
453          header.packet_sequence_number)) {
454    DVLOG(1) << ENDPOINT << "Packet " << header.packet_sequence_number
455             << " no longer being waited for.  Discarding.";
456    // TODO(jri): Log reception of duplicate packets or packets the peer has
457    // told us to stop waiting for.
458    return false;
459  }
460
461  if (version_negotiation_state_ != NEGOTIATED_VERSION) {
462    if (is_server_) {
463      if (!header.public_header.version_flag) {
464        DLOG(WARNING) << ENDPOINT << "Packet " << header.packet_sequence_number
465                      << " without version flag before version negotiated.";
466        // Packets should have the version flag till version negotiation is
467        // done.
468        CloseConnection(QUIC_INVALID_VERSION, false);
469        return false;
470      } else {
471        DCHECK_EQ(1u, header.public_header.versions.size());
472        DCHECK_EQ(header.public_header.versions[0], version());
473        version_negotiation_state_ = NEGOTIATED_VERSION;
474        visitor_->OnSuccessfulVersionNegotiation(version());
475      }
476    } else {
477      DCHECK(!header.public_header.version_flag);
478      // If the client gets a packet without the version flag from the server
479      // it should stop sending version since the version negotiation is done.
480      packet_generator_.StopSendingVersion();
481      version_negotiation_state_ = NEGOTIATED_VERSION;
482      visitor_->OnSuccessfulVersionNegotiation(version());
483    }
484  }
485
486  DCHECK_EQ(NEGOTIATED_VERSION, version_negotiation_state_);
487
488  --stats_.packets_dropped;
489  DVLOG(1) << ENDPOINT << "Received packet header: " << header;
490  last_header_ = header;
491  DCHECK(connected_);
492  return true;
493}
494
495void QuicConnection::OnFecProtectedPayload(StringPiece payload) {
496  DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
497  DCHECK_NE(0u, last_header_.fec_group);
498  QuicFecGroup* group = GetFecGroup();
499  if (group != NULL) {
500    group->Update(last_decrypted_packet_level_, last_header_, payload);
501  }
502}
503
504bool QuicConnection::OnStreamFrame(const QuicStreamFrame& frame) {
505  DCHECK(connected_);
506  if (debug_visitor_) {
507    debug_visitor_->OnStreamFrame(frame);
508  }
509  if (frame.stream_id != kCryptoStreamId &&
510      last_decrypted_packet_level_ == ENCRYPTION_NONE) {
511    DLOG(WARNING) << ENDPOINT
512                  << "Received an unencrypted data frame: closing connection";
513    SendConnectionClose(QUIC_UNENCRYPTED_STREAM_DATA);
514    return false;
515  }
516  last_stream_frames_.push_back(frame);
517  return true;
518}
519
520bool QuicConnection::OnAckFrame(const QuicAckFrame& incoming_ack) {
521  DCHECK(connected_);
522  if (debug_visitor_) {
523    debug_visitor_->OnAckFrame(incoming_ack);
524  }
525  DVLOG(1) << ENDPOINT << "OnAckFrame: " << incoming_ack;
526
527  if (last_header_.packet_sequence_number <= largest_seen_packet_with_ack_) {
528    DVLOG(1) << ENDPOINT << "Received an old ack frame: ignoring";
529    return true;
530  }
531
532  if (!ValidateAckFrame(incoming_ack)) {
533    SendConnectionClose(QUIC_INVALID_ACK_DATA);
534    return false;
535  }
536
537  last_ack_frames_.push_back(incoming_ack);
538  return connected_;
539}
540
541void QuicConnection::ProcessAckFrame(const QuicAckFrame& incoming_ack) {
542  largest_seen_packet_with_ack_ = last_header_.packet_sequence_number;
543  received_packet_manager_.UpdatePacketInformationReceivedByPeer(
544      incoming_ack.received_info);
545  if (version() <= QUIC_VERSION_15) {
546    ProcessStopWaitingFrame(incoming_ack.sent_info);
547  }
548
549  sent_entropy_manager_.ClearEntropyBefore(
550      received_packet_manager_.least_packet_awaited_by_peer() - 1);
551
552  sent_packet_manager_.OnIncomingAck(incoming_ack.received_info,
553                                     time_of_last_received_packet_);
554  if (sent_packet_manager_.HasPendingRetransmissions()) {
555    WriteIfNotBlocked();
556  }
557
558  // Always reset the retransmission alarm when an ack comes in, since we now
559  // have a better estimate of the current rtt than when it was set.
560  retransmission_alarm_->Cancel();
561  QuicTime retransmission_time =
562      sent_packet_manager_.GetRetransmissionTime();
563  if (retransmission_time != QuicTime::Zero()) {
564    retransmission_alarm_->Set(retransmission_time);
565  }
566}
567
568void QuicConnection::ProcessStopWaitingFrame(
569    const QuicStopWaitingFrame& stop_waiting) {
570  largest_seen_packet_with_stop_waiting_ = last_header_.packet_sequence_number;
571  received_packet_manager_.UpdatePacketInformationSentByPeer(stop_waiting);
572  // Possibly close any FecGroups which are now irrelevant.
573  CloseFecGroupsBefore(stop_waiting.least_unacked + 1);
574}
575
576bool QuicConnection::OnCongestionFeedbackFrame(
577    const QuicCongestionFeedbackFrame& feedback) {
578  DCHECK(connected_);
579  if (debug_visitor_) {
580    debug_visitor_->OnCongestionFeedbackFrame(feedback);
581  }
582  last_congestion_frames_.push_back(feedback);
583  return connected_;
584}
585
586bool QuicConnection::OnStopWaitingFrame(const QuicStopWaitingFrame& frame) {
587  DCHECK(connected_);
588
589  if (last_header_.packet_sequence_number <=
590      largest_seen_packet_with_stop_waiting_) {
591    DVLOG(1) << ENDPOINT << "Received an old stop waiting frame: ignoring";
592    return true;
593  }
594
595  if (!ValidateStopWaitingFrame(frame)) {
596    SendConnectionClose(QUIC_INVALID_STOP_WAITING_DATA);
597    return false;
598  }
599
600  if (debug_visitor_) {
601    debug_visitor_->OnStopWaitingFrame(frame);
602  }
603
604  last_stop_waiting_frames_.push_back(frame);
605  return connected_;
606}
607
608bool QuicConnection::OnPingFrame(const QuicPingFrame& frame) {
609  DCHECK(connected_);
610  if (debug_visitor_) {
611    debug_visitor_->OnPingFrame(frame);
612  }
613  return true;
614}
615
616bool QuicConnection::ValidateAckFrame(const QuicAckFrame& incoming_ack) {
617  if (incoming_ack.received_info.largest_observed >
618      packet_generator_.sequence_number()) {
619    DLOG(ERROR) << ENDPOINT << "Peer's observed unsent packet:"
620                << incoming_ack.received_info.largest_observed << " vs "
621                << packet_generator_.sequence_number();
622    // We got an error for data we have not sent.  Error out.
623    return false;
624  }
625
626  if (incoming_ack.received_info.largest_observed <
627          received_packet_manager_.peer_largest_observed_packet()) {
628    DLOG(ERROR) << ENDPOINT << "Peer's largest_observed packet decreased:"
629                << incoming_ack.received_info.largest_observed << " vs "
630                << received_packet_manager_.peer_largest_observed_packet();
631    // A new ack has a diminished largest_observed value.  Error out.
632    // If this was an old packet, we wouldn't even have checked.
633    return false;
634  }
635
636  if (version() <= QUIC_VERSION_15) {
637    if (!ValidateStopWaitingFrame(incoming_ack.sent_info)) {
638      return false;
639    }
640  }
641
642  if (!incoming_ack.received_info.missing_packets.empty() &&
643      *incoming_ack.received_info.missing_packets.rbegin() >
644      incoming_ack.received_info.largest_observed) {
645    DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
646                << *incoming_ack.received_info.missing_packets.rbegin()
647                << " which is greater than largest observed: "
648                << incoming_ack.received_info.largest_observed;
649    return false;
650  }
651
652  if (!incoming_ack.received_info.missing_packets.empty() &&
653      *incoming_ack.received_info.missing_packets.begin() <
654      received_packet_manager_.least_packet_awaited_by_peer()) {
655    DLOG(ERROR) << ENDPOINT << "Peer sent missing packet: "
656                << *incoming_ack.received_info.missing_packets.begin()
657                << " which is smaller than least_packet_awaited_by_peer_: "
658                << received_packet_manager_.least_packet_awaited_by_peer();
659    return false;
660  }
661
662  if (!sent_entropy_manager_.IsValidEntropy(
663          incoming_ack.received_info.largest_observed,
664          incoming_ack.received_info.missing_packets,
665          incoming_ack.received_info.entropy_hash)) {
666    DLOG(ERROR) << ENDPOINT << "Peer sent invalid entropy.";
667    return false;
668  }
669
670  for (SequenceNumberSet::const_iterator iter =
671           incoming_ack.received_info.revived_packets.begin();
672       iter != incoming_ack.received_info.revived_packets.end(); ++iter) {
673    if (!ContainsKey(incoming_ack.received_info.missing_packets, *iter)) {
674      DLOG(ERROR) << ENDPOINT
675                  << "Peer specified revived packet which was not missing.";
676      return false;
677    }
678  }
679  return true;
680}
681
682bool QuicConnection::ValidateStopWaitingFrame(
683    const QuicStopWaitingFrame& stop_waiting) {
684  if (stop_waiting.least_unacked <
685      received_packet_manager_.peer_least_packet_awaiting_ack()) {
686    DLOG(ERROR) << ENDPOINT << "Peer's sent low least_unacked: "
687                << stop_waiting.least_unacked << " vs "
688                << received_packet_manager_.peer_least_packet_awaiting_ack();
689    // We never process old ack frames, so this number should only increase.
690    return false;
691  }
692
693  if (stop_waiting.least_unacked >
694      last_header_.packet_sequence_number) {
695    DLOG(ERROR) << ENDPOINT << "Peer sent least_unacked:"
696                << stop_waiting.least_unacked
697                << " greater than the enclosing packet sequence number:"
698                << last_header_.packet_sequence_number;
699    return false;
700  }
701
702  return true;
703}
704
705void QuicConnection::OnFecData(const QuicFecData& fec) {
706  DCHECK_EQ(IN_FEC_GROUP, last_header_.is_in_fec_group);
707  DCHECK_NE(0u, last_header_.fec_group);
708  QuicFecGroup* group = GetFecGroup();
709  if (group != NULL) {
710    group->UpdateFec(last_decrypted_packet_level_,
711                     last_header_.packet_sequence_number, fec);
712  }
713}
714
715bool QuicConnection::OnRstStreamFrame(const QuicRstStreamFrame& frame) {
716  DCHECK(connected_);
717  if (debug_visitor_) {
718    debug_visitor_->OnRstStreamFrame(frame);
719  }
720  DVLOG(1) << ENDPOINT << "Stream reset with error "
721           << QuicUtils::StreamErrorToString(frame.error_code);
722  last_rst_frames_.push_back(frame);
723  return connected_;
724}
725
726bool QuicConnection::OnConnectionCloseFrame(
727    const QuicConnectionCloseFrame& frame) {
728  DCHECK(connected_);
729  if (debug_visitor_) {
730    debug_visitor_->OnConnectionCloseFrame(frame);
731  }
732  DVLOG(1) << ENDPOINT << "Connection " << connection_id()
733           << " closed with error "
734           << QuicUtils::ErrorToString(frame.error_code)
735           << " " << frame.error_details;
736  last_close_frames_.push_back(frame);
737  return connected_;
738}
739
740bool QuicConnection::OnGoAwayFrame(const QuicGoAwayFrame& frame) {
741  DCHECK(connected_);
742  if (debug_visitor_) {
743    debug_visitor_->OnGoAwayFrame(frame);
744  }
745  DVLOG(1) << ENDPOINT << "Go away received with error "
746           << QuicUtils::ErrorToString(frame.error_code)
747           << " and reason:" << frame.reason_phrase;
748  last_goaway_frames_.push_back(frame);
749  return connected_;
750}
751
752bool QuicConnection::OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) {
753  DCHECK(connected_);
754  if (debug_visitor_) {
755    debug_visitor_->OnWindowUpdateFrame(frame);
756  }
757  DVLOG(1) << ENDPOINT << "WindowUpdate received for stream: "
758           << frame.stream_id << " with byte offset: " << frame.byte_offset;
759  last_window_update_frames_.push_back(frame);
760  return connected_;
761}
762
763bool QuicConnection::OnBlockedFrame(const QuicBlockedFrame& frame) {
764  DCHECK(connected_);
765  if (debug_visitor_) {
766    debug_visitor_->OnBlockedFrame(frame);
767  }
768  DVLOG(1) << ENDPOINT << "Blocked frame received for stream: "
769           << frame.stream_id;
770  last_blocked_frames_.push_back(frame);
771  return connected_;
772}
773
774void QuicConnection::OnPacketComplete() {
775  // Don't do anything if this packet closed the connection.
776  if (!connected_) {
777    ClearLastFrames();
778    return;
779  }
780
781  DVLOG(1) << ENDPOINT << (last_packet_revived_ ? "Revived" : "Got")
782           << " packet " << last_header_.packet_sequence_number
783           << " with " << last_ack_frames_.size() << " acks, "
784           << last_congestion_frames_.size() << " congestions, "
785           << last_stop_waiting_frames_.size() << " stop_waiting, "
786           << last_goaway_frames_.size() << " goaways, "
787           << last_window_update_frames_.size() << " window updates, "
788           << last_blocked_frames_.size() << " blocked, "
789           << last_rst_frames_.size() << " rsts, "
790           << last_close_frames_.size() << " closes, "
791           << last_stream_frames_.size()
792           << " stream frames for "
793           << last_header_.public_header.connection_id;
794
795  // Call MaybeQueueAck() before recording the received packet, since we want
796  // to trigger an ack if the newly received packet was previously missing.
797  MaybeQueueAck();
798
799  // Record received or revived packet to populate ack info correctly before
800  // processing stream frames, since the processing may result in a response
801  // packet with a bundled ack.
802  if (last_packet_revived_) {
803    received_packet_manager_.RecordPacketRevived(
804        last_header_.packet_sequence_number);
805  } else {
806    received_packet_manager_.RecordPacketReceived(
807        last_size_, last_header_, time_of_last_received_packet_);
808  }
809
810  if (!last_stream_frames_.empty()) {
811    visitor_->OnStreamFrames(last_stream_frames_);
812  }
813
814  for (size_t i = 0; i < last_stream_frames_.size(); ++i) {
815    stats_.stream_bytes_received +=
816        last_stream_frames_[i].data.TotalBufferSize();
817  }
818
819  // Process window updates, blocked, stream resets, acks, then congestion
820  // feedback.
821  if (!last_window_update_frames_.empty()) {
822    visitor_->OnWindowUpdateFrames(last_window_update_frames_);
823  }
824  if (!last_blocked_frames_.empty()) {
825    visitor_->OnBlockedFrames(last_blocked_frames_);
826  }
827  for (size_t i = 0; i < last_goaway_frames_.size(); ++i) {
828    visitor_->OnGoAway(last_goaway_frames_[i]);
829  }
830  for (size_t i = 0; i < last_rst_frames_.size(); ++i) {
831    visitor_->OnRstStream(last_rst_frames_[i]);
832  }
833  for (size_t i = 0; i < last_ack_frames_.size(); ++i) {
834    ProcessAckFrame(last_ack_frames_[i]);
835  }
836  for (size_t i = 0; i < last_congestion_frames_.size(); ++i) {
837    sent_packet_manager_.OnIncomingQuicCongestionFeedbackFrame(
838        last_congestion_frames_[i], time_of_last_received_packet_);
839  }
840  for (size_t i = 0; i < last_stop_waiting_frames_.size(); ++i) {
841    ProcessStopWaitingFrame(last_stop_waiting_frames_[i]);
842  }
843  if (!last_close_frames_.empty()) {
844    CloseConnection(last_close_frames_[0].error_code, true);
845    DCHECK(!connected_);
846  }
847
848  // If there are new missing packets to report, send an ack immediately.
849  if (received_packet_manager_.HasNewMissingPackets()) {
850    ack_queued_ = true;
851    ack_alarm_->Cancel();
852  }
853
854  UpdateStopWaitingCount();
855
856  ClearLastFrames();
857}
858
859void QuicConnection::MaybeQueueAck() {
860  // If the incoming packet was missing, send an ack immediately.
861  ack_queued_ = received_packet_manager_.IsMissing(
862      last_header_.packet_sequence_number);
863
864  if (!ack_queued_ && ShouldLastPacketInstigateAck()) {
865    if (ack_alarm_->IsSet()) {
866      ack_queued_ = true;
867    } else {
868      // Send an ack much more quickly for crypto handshake packets.
869      QuicTime::Delta delayed_ack_time = sent_packet_manager_.DelayedAckTime();
870      if (last_stream_frames_.size() == 1 &&
871          last_stream_frames_[0].stream_id == kCryptoStreamId) {
872        delayed_ack_time = QuicTime::Delta::Zero();
873      }
874      ack_alarm_->Set(clock_->ApproximateNow().Add(delayed_ack_time));
875      DVLOG(1) << "Ack timer set; next packet or timer will trigger ACK.";
876    }
877  }
878
879  if (ack_queued_) {
880    ack_alarm_->Cancel();
881  }
882}
883
884void QuicConnection::ClearLastFrames() {
885  last_stream_frames_.clear();
886  last_goaway_frames_.clear();
887  last_window_update_frames_.clear();
888  last_blocked_frames_.clear();
889  last_rst_frames_.clear();
890  last_ack_frames_.clear();
891  last_stop_waiting_frames_.clear();
892  last_congestion_frames_.clear();
893}
894
895QuicAckFrame* QuicConnection::CreateAckFrame() {
896  QuicAckFrame* outgoing_ack = new QuicAckFrame();
897  received_packet_manager_.UpdateReceivedPacketInfo(
898      &(outgoing_ack->received_info), clock_->ApproximateNow());
899  UpdateStopWaiting(&(outgoing_ack->sent_info));
900  DVLOG(1) << ENDPOINT << "Creating ack frame: " << *outgoing_ack;
901  return outgoing_ack;
902}
903
904QuicCongestionFeedbackFrame* QuicConnection::CreateFeedbackFrame() {
905  return new QuicCongestionFeedbackFrame(outgoing_congestion_feedback_);
906}
907
908QuicStopWaitingFrame* QuicConnection::CreateStopWaitingFrame() {
909  QuicStopWaitingFrame stop_waiting;
910  UpdateStopWaiting(&stop_waiting);
911  return new QuicStopWaitingFrame(stop_waiting);
912}
913
914bool QuicConnection::ShouldLastPacketInstigateAck() const {
915  if (!last_stream_frames_.empty() ||
916      !last_goaway_frames_.empty() ||
917      !last_rst_frames_.empty() ||
918      !last_window_update_frames_.empty() ||
919      !last_blocked_frames_.empty()) {
920    return true;
921  }
922
923  if (!last_ack_frames_.empty() &&
924      last_ack_frames_.back().received_info.is_truncated) {
925    return true;
926  }
927  return false;
928}
929
930void QuicConnection::UpdateStopWaitingCount() {
931  if (last_ack_frames_.empty()) {
932    return;
933  }
934
935  // If the peer is still waiting for a packet that we are no longer planning to
936  // send, send an ack to raise the high water mark.
937  if (!last_ack_frames_.back().received_info.missing_packets.empty() &&
938      GetLeastUnacked() >
939          *last_ack_frames_.back().received_info.missing_packets.begin()) {
940    ++stop_waiting_count_;
941  } else {
942    stop_waiting_count_ = 0;
943  }
944}
945
946QuicPacketSequenceNumber QuicConnection::GetLeastUnacked() const {
947  return sent_packet_manager_.HasUnackedPackets() ?
948      sent_packet_manager_.GetLeastUnackedSentPacket() :
949      packet_generator_.sequence_number() + 1;
950}
951
952void QuicConnection::MaybeSendInResponseToPacket() {
953  if (!connected_) {
954    return;
955  }
956  ScopedPacketBundler bundler(this, ack_queued_ ? SEND_ACK : NO_ACK);
957
958  // Now that we have received an ack, we might be able to send packets which
959  // are queued locally, or drain streams which are blocked.
960  if (CanWrite(HAS_RETRANSMITTABLE_DATA)) {
961    OnCanWrite();
962  }
963}
964
965void QuicConnection::SendVersionNegotiationPacket() {
966  // TODO(alyssar): implement zero server state negotiation.
967  pending_version_negotiation_packet_ = true;
968  if (writer_->IsWriteBlocked()) {
969    visitor_->OnWriteBlocked();
970    return;
971  }
972  scoped_ptr<QuicEncryptedPacket> version_packet(
973      packet_generator_.SerializeVersionNegotiationPacket(
974          framer_.supported_versions()));
975  WriteResult result = writer_->WritePacket(
976      version_packet->data(), version_packet->length(),
977      self_address().address(), peer_address());
978
979  if (result.status == WRITE_STATUS_ERROR) {
980    // We can't send an error as the socket is presumably borked.
981    CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
982    return;
983  }
984  if (result.status == WRITE_STATUS_BLOCKED) {
985    visitor_->OnWriteBlocked();
986    if (writer_->IsWriteBlockedDataBuffered()) {
987      pending_version_negotiation_packet_ = false;
988    }
989    return;
990  }
991
992  pending_version_negotiation_packet_ = false;
993}
994
995QuicConsumedData QuicConnection::SendStreamData(
996    QuicStreamId id,
997    const IOVector& data,
998    QuicStreamOffset offset,
999    bool fin,
1000    FecProtection fec_protection,
1001    QuicAckNotifier::DelegateInterface* delegate) {
1002  if (!fin && data.Empty()) {
1003    LOG(DFATAL) << "Attempt to send empty stream frame";
1004  }
1005
1006  // This notifier will be owned by the AckNotifierManager (or deleted below if
1007  // no data or FIN was consumed).
1008  QuicAckNotifier* notifier = NULL;
1009  if (delegate) {
1010    notifier = new QuicAckNotifier(delegate);
1011  }
1012
1013  // Opportunistically bundle an ack with every outgoing packet.
1014  // Particularly, we want to bundle with handshake packets since we don't know
1015  // which decrypter will be used on an ack packet following a handshake
1016  // packet (a handshake packet from client to server could result in a REJ or a
1017  // SHLO from the server, leading to two different decrypters at the server.)
1018  //
1019  // TODO(jri): Note that ConsumeData may cause a response packet to be sent.
1020  // We may end up sending stale ack information if there are undecryptable
1021  // packets hanging around and/or there are revivable packets which may get
1022  // handled after this packet is sent. Change ScopedPacketBundler to do the
1023  // right thing: check ack_queued_, and then check undecryptable packets and
1024  // also if there is possibility of revival. Only bundle an ack if there's no
1025  // processing left that may cause received_info_ to change.
1026  ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1027  QuicConsumedData consumed_data =
1028      packet_generator_.ConsumeData(id, data, offset, fin, fec_protection,
1029                                    notifier);
1030
1031  if (notifier &&
1032      (consumed_data.bytes_consumed == 0 && !consumed_data.fin_consumed)) {
1033    // No data was consumed, nor was a fin consumed, so delete the notifier.
1034    delete notifier;
1035  }
1036
1037  return consumed_data;
1038}
1039
1040void QuicConnection::SendRstStream(QuicStreamId id,
1041                                   QuicRstStreamErrorCode error,
1042                                   QuicStreamOffset bytes_written) {
1043  // Opportunistically bundle an ack with this outgoing packet.
1044  ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1045  packet_generator_.AddControlFrame(QuicFrame(new QuicRstStreamFrame(
1046      id, AdjustErrorForVersion(error, version()), bytes_written)));
1047}
1048
1049void QuicConnection::SendWindowUpdate(QuicStreamId id,
1050                                      QuicStreamOffset byte_offset) {
1051  // Opportunistically bundle an ack with this outgoing packet.
1052  ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1053  packet_generator_.AddControlFrame(
1054      QuicFrame(new QuicWindowUpdateFrame(id, byte_offset)));
1055}
1056
1057void QuicConnection::SendBlocked(QuicStreamId id) {
1058  // Opportunistically bundle an ack with this outgoing packet.
1059  ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1060  packet_generator_.AddControlFrame(QuicFrame(new QuicBlockedFrame(id)));
1061}
1062
1063const QuicConnectionStats& QuicConnection::GetStats() {
1064  // Update rtt and estimated bandwidth.
1065  stats_.min_rtt_us =
1066      sent_packet_manager_.GetRttStats()->min_rtt().ToMicroseconds();
1067  stats_.srtt_us =
1068      sent_packet_manager_.GetRttStats()->SmoothedRtt().ToMicroseconds();
1069  stats_.estimated_bandwidth =
1070      sent_packet_manager_.BandwidthEstimate().ToBytesPerSecond();
1071  stats_.congestion_window = sent_packet_manager_.GetCongestionWindow();
1072  stats_.max_packet_size = packet_generator_.max_packet_length();
1073  return stats_;
1074}
1075
1076void QuicConnection::ProcessUdpPacket(const IPEndPoint& self_address,
1077                                      const IPEndPoint& peer_address,
1078                                      const QuicEncryptedPacket& packet) {
1079  if (!connected_) {
1080    return;
1081  }
1082  if (debug_visitor_) {
1083    debug_visitor_->OnPacketReceived(self_address, peer_address, packet);
1084  }
1085  last_packet_revived_ = false;
1086  last_size_ = packet.length();
1087
1088  CheckForAddressMigration(self_address, peer_address);
1089
1090  stats_.bytes_received += packet.length();
1091  ++stats_.packets_received;
1092
1093  if (!framer_.ProcessPacket(packet)) {
1094    // If we are unable to decrypt this packet, it might be
1095    // because the CHLO or SHLO packet was lost.
1096    if (encryption_level_ != ENCRYPTION_FORWARD_SECURE &&
1097        framer_.error() == QUIC_DECRYPTION_FAILURE &&
1098        undecryptable_packets_.size() < kMaxUndecryptablePackets) {
1099      QueueUndecryptablePacket(packet);
1100    }
1101    DVLOG(1) << ENDPOINT << "Unable to process packet.  Last packet processed: "
1102             << last_header_.packet_sequence_number;
1103    return;
1104  }
1105
1106  ++stats_.packets_processed;
1107  MaybeProcessUndecryptablePackets();
1108  MaybeProcessRevivedPacket();
1109  MaybeSendInResponseToPacket();
1110  SetPingAlarm();
1111}
1112
1113void QuicConnection::CheckForAddressMigration(
1114    const IPEndPoint& self_address, const IPEndPoint& peer_address) {
1115  peer_ip_changed_ = false;
1116  peer_port_changed_ = false;
1117  self_ip_changed_ = false;
1118  self_port_changed_ = false;
1119
1120  if (peer_address_.address().empty()) {
1121    peer_address_ = peer_address;
1122  }
1123  if (self_address_.address().empty()) {
1124    self_address_ = self_address;
1125  }
1126
1127  if (!peer_address.address().empty() && !peer_address_.address().empty()) {
1128    peer_ip_changed_ = (peer_address.address() != peer_address_.address());
1129    peer_port_changed_ = (peer_address.port() != peer_address_.port());
1130
1131    // Store in case we want to migrate connection in ProcessValidatedPacket.
1132    migrating_peer_port_ = peer_address.port();
1133  }
1134
1135  if (!self_address.address().empty() && !self_address_.address().empty()) {
1136    self_ip_changed_ = (self_address.address() != self_address_.address());
1137    self_port_changed_ = (self_address.port() != self_address_.port());
1138  }
1139}
1140
1141void QuicConnection::OnCanWrite() {
1142  DCHECK(!writer_->IsWriteBlocked());
1143
1144  WriteQueuedPackets();
1145  WritePendingRetransmissions();
1146
1147  // Sending queued packets may have caused the socket to become write blocked,
1148  // or the congestion manager to prohibit sending.  If we've sent everything
1149  // we had queued and we're still not blocked, let the visitor know it can
1150  // write more.
1151  if (!CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1152    return;
1153  }
1154
1155  {  // Limit the scope of the bundler.
1156    // Set |include_ack| to false in bundler; ack inclusion happens elsewhere.
1157    ScopedPacketBundler bundler(this, NO_ACK);
1158    visitor_->OnCanWrite();
1159  }
1160
1161  // After the visitor writes, it may have caused the socket to become write
1162  // blocked or the congestion manager to prohibit sending, so check again.
1163  if (visitor_->WillingAndAbleToWrite() &&
1164      !resume_writes_alarm_->IsSet() &&
1165      CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1166    // We're not write blocked, but some stream didn't write out all of its
1167    // bytes. Register for 'immediate' resumption so we'll keep writing after
1168    // other connections and events have had a chance to use the thread.
1169    resume_writes_alarm_->Set(clock_->ApproximateNow());
1170  }
1171}
1172
1173void QuicConnection::WriteIfNotBlocked() {
1174  if (!writer_->IsWriteBlocked()) {
1175    OnCanWrite();
1176  }
1177}
1178
1179bool QuicConnection::ProcessValidatedPacket() {
1180  if ((!FLAGS_quic_allow_port_migration && peer_port_changed_) ||
1181      peer_ip_changed_ || self_ip_changed_ || self_port_changed_) {
1182    SendConnectionCloseWithDetails(
1183        QUIC_ERROR_MIGRATING_ADDRESS,
1184        "Neither IP address migration, nor self port migration are supported.");
1185    return false;
1186  }
1187
1188  // Port migration is supported, do it now if port has changed.
1189  if (FLAGS_quic_allow_port_migration &&
1190      peer_port_changed_) {
1191    DVLOG(1) << ENDPOINT << "Peer's port changed from "
1192             << peer_address_.port() << " to " << migrating_peer_port_
1193             << ", migrating connection.";
1194    peer_address_ = IPEndPoint(peer_address_.address(), migrating_peer_port_);
1195  }
1196
1197  time_of_last_received_packet_ = clock_->Now();
1198  DVLOG(1) << ENDPOINT << "time of last received packet: "
1199           << time_of_last_received_packet_.ToDebuggingValue();
1200
1201  if (is_server_ && encryption_level_ == ENCRYPTION_NONE &&
1202      last_size_ > packet_generator_.max_packet_length()) {
1203    packet_generator_.set_max_packet_length(last_size_);
1204  }
1205  return true;
1206}
1207
1208void QuicConnection::WriteQueuedPackets() {
1209  DCHECK(!writer_->IsWriteBlocked());
1210
1211  if (pending_version_negotiation_packet_) {
1212    SendVersionNegotiationPacket();
1213  }
1214
1215  QueuedPacketList::iterator packet_iterator = queued_packets_.begin();
1216  while (!writer_->IsWriteBlocked() &&
1217         packet_iterator != queued_packets_.end()) {
1218    if (WritePacket(*packet_iterator)) {
1219      delete packet_iterator->packet;
1220      packet_iterator = queued_packets_.erase(packet_iterator);
1221    } else {
1222      // Continue, because some queued packets may still be writable.
1223      // This can happen if a retransmit send fails.
1224      ++packet_iterator;
1225    }
1226  }
1227}
1228
1229void QuicConnection::WritePendingRetransmissions() {
1230  // Keep writing as long as there's a pending retransmission which can be
1231  // written.
1232  while (sent_packet_manager_.HasPendingRetransmissions()) {
1233    const QuicSentPacketManager::PendingRetransmission pending =
1234        sent_packet_manager_.NextPendingRetransmission();
1235    if (GetPacketType(&pending.retransmittable_frames) == NORMAL &&
1236        !CanWrite(HAS_RETRANSMITTABLE_DATA)) {
1237      break;
1238    }
1239
1240    // Re-packetize the frames with a new sequence number for retransmission.
1241    // Retransmitted data packets do not use FEC, even when it's enabled.
1242    // Retransmitted packets use the same sequence number length as the
1243    // original.
1244    // Flush the packet generator before making a new packet.
1245    // TODO(ianswett): Implement ReserializeAllFrames as a separate path that
1246    // does not require the creator to be flushed.
1247    packet_generator_.FlushAllQueuedFrames();
1248    SerializedPacket serialized_packet = packet_generator_.ReserializeAllFrames(
1249        pending.retransmittable_frames.frames(),
1250        pending.sequence_number_length);
1251
1252    DVLOG(1) << ENDPOINT << "Retransmitting " << pending.sequence_number
1253             << " as " << serialized_packet.sequence_number;
1254    if (debug_visitor_) {
1255      debug_visitor_->OnPacketRetransmitted(
1256          pending.sequence_number, serialized_packet.sequence_number);
1257    }
1258    sent_packet_manager_.OnRetransmittedPacket(
1259        pending.sequence_number,
1260        serialized_packet.sequence_number);
1261
1262    SendOrQueuePacket(pending.retransmittable_frames.encryption_level(),
1263                      serialized_packet,
1264                      pending.transmission_type);
1265  }
1266}
1267
1268void QuicConnection::RetransmitUnackedPackets(
1269    RetransmissionType retransmission_type) {
1270  sent_packet_manager_.RetransmitUnackedPackets(retransmission_type);
1271
1272  WriteIfNotBlocked();
1273}
1274
1275void QuicConnection::NeuterUnencryptedPackets() {
1276  sent_packet_manager_.NeuterUnencryptedPackets();
1277  // This may have changed the retransmission timer, so re-arm it.
1278  retransmission_alarm_->Cancel();
1279  QuicTime retransmission_time = sent_packet_manager_.GetRetransmissionTime();
1280  if (retransmission_time != QuicTime::Zero()) {
1281    retransmission_alarm_->Set(retransmission_time);
1282  }
1283}
1284
1285bool QuicConnection::ShouldGeneratePacket(
1286    TransmissionType transmission_type,
1287    HasRetransmittableData retransmittable,
1288    IsHandshake handshake) {
1289  // We should serialize handshake packets immediately to ensure that they
1290  // end up sent at the right encryption level.
1291  if (handshake == IS_HANDSHAKE) {
1292    return true;
1293  }
1294
1295  return CanWrite(retransmittable);
1296}
1297
1298bool QuicConnection::CanWrite(HasRetransmittableData retransmittable) {
1299  if (writer_->IsWriteBlocked()) {
1300    visitor_->OnWriteBlocked();
1301    return false;
1302  }
1303
1304  send_alarm_->Cancel();
1305  QuicTime now = clock_->Now();
1306  QuicTime::Delta delay = sent_packet_manager_.TimeUntilSend(
1307      now, retransmittable);
1308  if (delay.IsInfinite()) {
1309    return false;
1310  }
1311
1312  // If the scheduler requires a delay, then we can not send this packet now.
1313  if (!delay.IsZero()) {
1314    send_alarm_->Set(now.Add(delay));
1315    DVLOG(1) << "Delaying sending.";
1316    return false;
1317  }
1318  return true;
1319}
1320
1321bool QuicConnection::WritePacket(QueuedPacket packet) {
1322  QuicPacketSequenceNumber sequence_number = packet.sequence_number;
1323  if (ShouldDiscardPacket(packet.encryption_level,
1324                          sequence_number,
1325                          packet.retransmittable)) {
1326    ++stats_.packets_discarded;
1327    return true;
1328  }
1329
1330  // If the packet is CONNECTION_CLOSE, we need to try to send it immediately
1331  // and encrypt it to hand it off to TimeWaitListManager.
1332  // If the packet is QUEUED, we don't re-consult the congestion control.
1333  // This ensures packets are sent in sequence number order.
1334  // TODO(ianswett): The congestion control should have been consulted before
1335  // serializing the packet, so this could be turned into a LOG_IF(DFATAL).
1336  if (packet.type == NORMAL && !CanWrite(packet.retransmittable)) {
1337    return false;
1338  }
1339
1340  // Some encryption algorithms require the packet sequence numbers not be
1341  // repeated.
1342  DCHECK_LE(sequence_number_of_last_sent_packet_, sequence_number);
1343  sequence_number_of_last_sent_packet_ = sequence_number;
1344
1345  QuicEncryptedPacket* encrypted = framer_.EncryptPacket(
1346      packet.encryption_level, sequence_number, *packet.packet);
1347  if (encrypted == NULL) {
1348    LOG(DFATAL) << ENDPOINT << "Failed to encrypt packet number "
1349                << sequence_number;
1350    // CloseConnection does not send close packet, so no infinite loop here.
1351    CloseConnection(QUIC_ENCRYPTION_FAILURE, false);
1352    return false;
1353  }
1354
1355  // Connection close packets are eventually owned by TimeWaitListManager.
1356  // Others are deleted at the end of this call.
1357  scoped_ptr<QuicEncryptedPacket> encrypted_deleter;
1358  if (packet.type == CONNECTION_CLOSE) {
1359    DCHECK(connection_close_packet_.get() == NULL);
1360    connection_close_packet_.reset(encrypted);
1361    // This assures we won't try to write *forced* packets when blocked.
1362    // Return true to stop processing.
1363    if (writer_->IsWriteBlocked()) {
1364      visitor_->OnWriteBlocked();
1365      return true;
1366    }
1367  } else {
1368    encrypted_deleter.reset(encrypted);
1369  }
1370
1371  LOG_IF(DFATAL, encrypted->length() >
1372         packet_generator_.max_packet_length())
1373      << "Writing an encrypted packet larger than max_packet_length:"
1374      << packet_generator_.max_packet_length() << " encrypted length: "
1375      << encrypted->length();
1376  DVLOG(1) << ENDPOINT << "Sending packet " << sequence_number
1377           << " : " << (packet.packet->is_fec_packet() ? "FEC " :
1378               (packet.retransmittable == HAS_RETRANSMITTABLE_DATA
1379                    ? "data bearing " : " ack only "))
1380           << ", encryption level: "
1381           << QuicUtils::EncryptionLevelToString(packet.encryption_level)
1382           << ", length:" << packet.packet->length() << ", encrypted length:"
1383           << encrypted->length();
1384  DVLOG(2) << ENDPOINT << "packet(" << sequence_number << "): " << std::endl
1385           << QuicUtils::StringToHexASCIIDump(packet.packet->AsStringPiece());
1386
1387  DCHECK(encrypted->length() <= kMaxPacketSize ||
1388         FLAGS_quic_allow_oversized_packets_for_test)
1389      << "Packet " << sequence_number << " will not be read; too large: "
1390      << packet.packet->length() << " " << encrypted->length() << " "
1391      << " close: " << (packet.type == CONNECTION_CLOSE ? "yes" : "no");
1392
1393  DCHECK(pending_write_.get() == NULL);
1394  pending_write_.reset(new QueuedPacket(packet));
1395
1396  WriteResult result = writer_->WritePacket(encrypted->data(),
1397                                            encrypted->length(),
1398                                            self_address().address(),
1399                                            peer_address());
1400  if (result.error_code == ERR_IO_PENDING) {
1401    DCHECK_EQ(WRITE_STATUS_BLOCKED, result.status);
1402  }
1403  if (debug_visitor_) {
1404    // Pass the write result to the visitor.
1405    debug_visitor_->OnPacketSent(sequence_number,
1406                                 packet.encryption_level,
1407                                 packet.transmission_type,
1408                                 *encrypted,
1409                                 result);
1410  }
1411  if (result.status == WRITE_STATUS_BLOCKED) {
1412    visitor_->OnWriteBlocked();
1413    // If the socket buffers the the data, then the packet should not
1414    // be queued and sent again, which would result in an unnecessary
1415    // duplicate packet being sent.  The helper must call OnPacketSent
1416    // when the packet is actually sent.
1417    if (writer_->IsWriteBlockedDataBuffered()) {
1418      return true;
1419    }
1420    pending_write_.reset();
1421    return false;
1422  }
1423
1424  if (OnPacketSent(result)) {
1425    return true;
1426  }
1427  return false;
1428}
1429
1430bool QuicConnection::ShouldDiscardPacket(
1431    EncryptionLevel level,
1432    QuicPacketSequenceNumber sequence_number,
1433    HasRetransmittableData retransmittable) {
1434  if (!connected_) {
1435    DVLOG(1) << ENDPOINT
1436             << "Not sending packet as connection is disconnected.";
1437    return true;
1438  }
1439
1440  // If the packet has been discarded before sending, don't send it.
1441  // This occurs if a packet gets serialized, queued, then discarded.
1442  if (!sent_packet_manager_.IsUnacked(sequence_number)) {
1443    DVLOG(1) << ENDPOINT << "Dropping packet before sending: "
1444             << sequence_number << " since it has already been discarded.";
1445    return true;
1446  }
1447
1448  if (encryption_level_ == ENCRYPTION_FORWARD_SECURE &&
1449      level == ENCRYPTION_NONE) {
1450    // Drop packets that are NULL encrypted since the peer won't accept them
1451    // anymore.
1452    DVLOG(1) << ENDPOINT << "Dropping NULL encrypted packet: "
1453             << sequence_number << " since the connection is forward secure.";
1454    LOG_IF(DFATAL,
1455           sent_packet_manager_.HasRetransmittableFrames(sequence_number))
1456        << "Once forward secure, all NULL encrypted packets should be "
1457        << "neutered.";
1458    return true;
1459  }
1460
1461  if (retransmittable == HAS_RETRANSMITTABLE_DATA &&
1462      !sent_packet_manager_.HasRetransmittableFrames(sequence_number)) {
1463    DVLOG(1) << ENDPOINT << "Dropping unacked packet: " << sequence_number
1464             << " A previous transmission was acked while write blocked.";
1465    return true;
1466  }
1467
1468  return false;
1469}
1470
1471bool QuicConnection::OnPacketSent(WriteResult result) {
1472  DCHECK_NE(WRITE_STATUS_BLOCKED, result.status);
1473  if (pending_write_.get() == NULL) {
1474    LOG(DFATAL) << "OnPacketSent called without a pending write.";
1475    return false;
1476  }
1477
1478  QuicPacketSequenceNumber sequence_number = pending_write_->sequence_number;
1479  TransmissionType transmission_type  = pending_write_->transmission_type;
1480  HasRetransmittableData retransmittable = pending_write_->retransmittable;
1481  size_t length = pending_write_->length;
1482  pending_write_.reset();
1483
1484  if (result.status == WRITE_STATUS_ERROR) {
1485    DVLOG(1) << "Write failed with error: " << result.error_code << " ("
1486             << ErrorToString(result.error_code) << ")";
1487    // We can't send an error as the socket is presumably borked.
1488    CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
1489    return false;
1490  }
1491
1492  QuicTime now = clock_->Now();
1493  if (transmission_type == NOT_RETRANSMISSION) {
1494    time_of_last_sent_new_packet_ = now;
1495  }
1496  SetPingAlarm();
1497  DVLOG(1) << ENDPOINT << "time of last sent packet: "
1498           << now.ToDebuggingValue();
1499
1500  // TODO(ianswett): Change the sequence number length and other packet creator
1501  // options by a more explicit API than setting a struct value directly.
1502  packet_generator_.UpdateSequenceNumberLength(
1503      received_packet_manager_.least_packet_awaited_by_peer(),
1504      sent_packet_manager_.GetCongestionWindow());
1505
1506  bool reset_retransmission_alarm =
1507      sent_packet_manager_.OnPacketSent(sequence_number, now, length,
1508                                        transmission_type, retransmittable);
1509
1510  if (reset_retransmission_alarm || !retransmission_alarm_->IsSet()) {
1511    retransmission_alarm_->Cancel();
1512    QuicTime retransmission_time = sent_packet_manager_.GetRetransmissionTime();
1513    if (retransmission_time != QuicTime::Zero()) {
1514      retransmission_alarm_->Set(retransmission_time);
1515    }
1516  }
1517
1518  stats_.bytes_sent += result.bytes_written;
1519  ++stats_.packets_sent;
1520
1521  if (transmission_type != NOT_RETRANSMISSION) {
1522    stats_.bytes_retransmitted += result.bytes_written;
1523    ++stats_.packets_retransmitted;
1524  }
1525
1526  return true;
1527}
1528
1529bool QuicConnection::OnSerializedPacket(
1530    const SerializedPacket& serialized_packet) {
1531  if (serialized_packet.retransmittable_frames) {
1532    serialized_packet.retransmittable_frames->
1533        set_encryption_level(encryption_level_);
1534  }
1535  sent_packet_manager_.OnSerializedPacket(serialized_packet);
1536  // The TransmissionType is NOT_RETRANSMISSION because all retransmissions
1537  // serialize packets and invoke SendOrQueuePacket directly.
1538  return SendOrQueuePacket(encryption_level_,
1539                           serialized_packet,
1540                           NOT_RETRANSMISSION);
1541}
1542
1543bool QuicConnection::SendOrQueuePacket(EncryptionLevel level,
1544                                       const SerializedPacket& packet,
1545                                       TransmissionType transmission_type) {
1546  if (packet.packet == NULL) {
1547    LOG(DFATAL) << "NULL packet passed in to SendOrQueuePacket";
1548    return true;
1549  }
1550
1551  sent_entropy_manager_.RecordPacketEntropyHash(packet.sequence_number,
1552                                                packet.entropy_hash);
1553  QueuedPacket queued_packet(packet, level, transmission_type);
1554  // If there are already queued packets, put this at the end,
1555  // unless it's ConnectionClose, in which case it is written immediately.
1556  if ((queued_packet.type == CONNECTION_CLOSE || queued_packets_.empty()) &&
1557      WritePacket(queued_packet)) {
1558    delete packet.packet;
1559    return true;
1560  }
1561  queued_packet.type = QUEUED;
1562  queued_packets_.push_back(queued_packet);
1563  return false;
1564}
1565
1566void QuicConnection::UpdateStopWaiting(QuicStopWaitingFrame* stop_waiting) {
1567  stop_waiting->least_unacked = GetLeastUnacked();
1568  stop_waiting->entropy_hash = sent_entropy_manager_.EntropyHash(
1569      stop_waiting->least_unacked - 1);
1570}
1571
1572void QuicConnection::SendPing() {
1573  if (retransmission_alarm_->IsSet()) {
1574    return;
1575  }
1576  if (version() <= QUIC_VERSION_17) {
1577    // TODO(rch): remove this when we remove version 17.
1578    // This is a horrible hideous hack which we should not support.
1579    IOVector data;
1580    char c_data[] = "C";
1581    data.Append(c_data, 1);
1582    QuicConsumedData consumed_data =
1583        packet_generator_.ConsumeData(kCryptoStreamId, data, 0, false,
1584                                      MAY_FEC_PROTECT, NULL);
1585    if (consumed_data.bytes_consumed == 0) {
1586      DLOG(ERROR) << "Unable to send ping!?";
1587    }
1588  } else {
1589    packet_generator_.AddControlFrame(QuicFrame(new QuicPingFrame));
1590  }
1591}
1592
1593void QuicConnection::SendAck() {
1594  ack_alarm_->Cancel();
1595  stop_waiting_count_ = 0;
1596  // TODO(rch): delay this until the CreateFeedbackFrame
1597  // method is invoked.  This requires changes SetShouldSendAck
1598  // to be a no-arg method, and re-jiggering its implementation.
1599  bool send_feedback = false;
1600  if (received_packet_manager_.GenerateCongestionFeedback(
1601          &outgoing_congestion_feedback_)) {
1602    DVLOG(1) << ENDPOINT << "Sending feedback: "
1603             << outgoing_congestion_feedback_;
1604    send_feedback = true;
1605  }
1606
1607  packet_generator_.SetShouldSendAck(send_feedback,
1608                                     version() > QUIC_VERSION_15);
1609}
1610
1611void QuicConnection::OnRetransmissionTimeout() {
1612  if (!sent_packet_manager_.HasUnackedPackets()) {
1613    return;
1614  }
1615
1616  sent_packet_manager_.OnRetransmissionTimeout();
1617  WriteIfNotBlocked();
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 != QuicTime::Zero()) {
1630      retransmission_alarm_->Set(rto_timeout);
1631    }
1632  }
1633}
1634
1635void QuicConnection::SetEncrypter(EncryptionLevel level,
1636                                  QuicEncrypter* encrypter) {
1637  framer_.SetEncrypter(level, encrypter);
1638}
1639
1640const QuicEncrypter* QuicConnection::encrypter(EncryptionLevel level) const {
1641  return framer_.encrypter(level);
1642}
1643
1644void QuicConnection::SetDefaultEncryptionLevel(EncryptionLevel level) {
1645  encryption_level_ = level;
1646  packet_generator_.set_encryption_level(level);
1647}
1648
1649void QuicConnection::SetDecrypter(QuicDecrypter* decrypter,
1650                                  EncryptionLevel level) {
1651  framer_.SetDecrypter(decrypter, level);
1652}
1653
1654void QuicConnection::SetAlternativeDecrypter(QuicDecrypter* decrypter,
1655                                             EncryptionLevel level,
1656                                             bool latch_once_used) {
1657  framer_.SetAlternativeDecrypter(decrypter, level, latch_once_used);
1658}
1659
1660const QuicDecrypter* QuicConnection::decrypter() const {
1661  return framer_.decrypter();
1662}
1663
1664const QuicDecrypter* QuicConnection::alternative_decrypter() const {
1665  return framer_.alternative_decrypter();
1666}
1667
1668void QuicConnection::QueueUndecryptablePacket(
1669    const QuicEncryptedPacket& packet) {
1670  DVLOG(1) << ENDPOINT << "Queueing undecryptable packet.";
1671  undecryptable_packets_.push_back(packet.Clone());
1672}
1673
1674void 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    STLDeleteElements(&undecryptable_packets_);
1698  }
1699}
1700
1701void QuicConnection::MaybeProcessRevivedPacket() {
1702  QuicFecGroup* group = GetFecGroup();
1703  if (!connected_ || group == NULL || !group->CanRevive()) {
1704    return;
1705  }
1706  QuicPacketHeader revived_header;
1707  char revived_payload[kMaxPacketSize];
1708  size_t len = group->Revive(&revived_header, revived_payload, kMaxPacketSize);
1709  revived_header.public_header.connection_id = connection_id_;
1710  revived_header.public_header.connection_id_length =
1711      last_header_.public_header.connection_id_length;
1712  revived_header.public_header.version_flag = false;
1713  revived_header.public_header.reset_flag = false;
1714  revived_header.public_header.sequence_number_length =
1715      last_header_.public_header.sequence_number_length;
1716  revived_header.fec_flag = false;
1717  revived_header.is_in_fec_group = NOT_IN_FEC_GROUP;
1718  revived_header.fec_group = 0;
1719  group_map_.erase(last_header_.fec_group);
1720  last_decrypted_packet_level_ = group->effective_encryption_level();
1721  DCHECK_LT(last_decrypted_packet_level_, NUM_ENCRYPTION_LEVELS);
1722  delete group;
1723
1724  last_packet_revived_ = true;
1725  if (debug_visitor_) {
1726    debug_visitor_->OnRevivedPacket(revived_header,
1727                                    StringPiece(revived_payload, len));
1728  }
1729
1730  ++stats_.packets_revived;
1731  framer_.ProcessRevivedPacket(&revived_header,
1732                               StringPiece(revived_payload, len));
1733}
1734
1735QuicFecGroup* QuicConnection::GetFecGroup() {
1736  QuicFecGroupNumber fec_group_num = last_header_.fec_group;
1737  if (fec_group_num == 0) {
1738    return NULL;
1739  }
1740  if (group_map_.count(fec_group_num) == 0) {
1741    if (group_map_.size() >= kMaxFecGroups) {  // Too many groups
1742      if (fec_group_num < group_map_.begin()->first) {
1743        // The group being requested is a group we've seen before and deleted.
1744        // Don't recreate it.
1745        return NULL;
1746      }
1747      // Clear the lowest group number.
1748      delete group_map_.begin()->second;
1749      group_map_.erase(group_map_.begin());
1750    }
1751    group_map_[fec_group_num] = new QuicFecGroup();
1752  }
1753  return group_map_[fec_group_num];
1754}
1755
1756void QuicConnection::SendConnectionClose(QuicErrorCode error) {
1757  SendConnectionCloseWithDetails(error, string());
1758}
1759
1760void QuicConnection::SendConnectionCloseWithDetails(QuicErrorCode error,
1761                                                    const string& details) {
1762  // If we're write blocked, WritePacket() will not send, but will capture the
1763  // serialized packet.
1764  SendConnectionClosePacket(error, details);
1765  if (connected_) {
1766    // It's possible that while sending the connection close packet, we get a
1767    // socket error and disconnect right then and there.  Avoid a double
1768    // disconnect in that case.
1769    CloseConnection(error, false);
1770  }
1771}
1772
1773void QuicConnection::SendConnectionClosePacket(QuicErrorCode error,
1774                                               const string& details) {
1775  DVLOG(1) << ENDPOINT << "Force closing " << connection_id()
1776           << " with error " << QuicUtils::ErrorToString(error)
1777           << " (" << error << ") " << details;
1778  ScopedPacketBundler ack_bundler(this, SEND_ACK);
1779  QuicConnectionCloseFrame* frame = new QuicConnectionCloseFrame();
1780  frame->error_code = error;
1781  frame->error_details = details;
1782  packet_generator_.AddControlFrame(QuicFrame(frame));
1783  packet_generator_.FlushAllQueuedFrames();
1784}
1785
1786void QuicConnection::CloseConnection(QuicErrorCode error, bool from_peer) {
1787  if (!connected_) {
1788    DLOG(DFATAL) << "Error: attempt to close an already closed connection"
1789                 << base::debug::StackTrace().ToString();
1790    return;
1791  }
1792  connected_ = false;
1793  visitor_->OnConnectionClosed(error, from_peer);
1794  // Cancel the alarms so they don't trigger any action now that the
1795  // connection is closed.
1796  ack_alarm_->Cancel();
1797  resume_writes_alarm_->Cancel();
1798  retransmission_alarm_->Cancel();
1799  send_alarm_->Cancel();
1800  timeout_alarm_->Cancel();
1801}
1802
1803void QuicConnection::SendGoAway(QuicErrorCode error,
1804                                QuicStreamId last_good_stream_id,
1805                                const string& reason) {
1806  DVLOG(1) << ENDPOINT << "Going away with error "
1807           << QuicUtils::ErrorToString(error)
1808           << " (" << error << ")";
1809
1810  // Opportunistically bundle an ack with this outgoing packet.
1811  ScopedPacketBundler ack_bundler(this, BUNDLE_PENDING_ACK);
1812  packet_generator_.AddControlFrame(
1813      QuicFrame(new QuicGoAwayFrame(error, last_good_stream_id, reason)));
1814}
1815
1816void QuicConnection::CloseFecGroupsBefore(
1817    QuicPacketSequenceNumber sequence_number) {
1818  FecGroupMap::iterator it = group_map_.begin();
1819  while (it != group_map_.end()) {
1820    // If this is the current group or the group doesn't protect this packet
1821    // we can ignore it.
1822    if (last_header_.fec_group == it->first ||
1823        !it->second->ProtectsPacketsBefore(sequence_number)) {
1824      ++it;
1825      continue;
1826    }
1827    QuicFecGroup* fec_group = it->second;
1828    DCHECK(!fec_group->CanRevive());
1829    FecGroupMap::iterator next = it;
1830    ++next;
1831    group_map_.erase(it);
1832    delete fec_group;
1833    it = next;
1834  }
1835}
1836
1837size_t QuicConnection::max_packet_length() const {
1838  return packet_generator_.max_packet_length();
1839}
1840
1841void QuicConnection::set_max_packet_length(size_t length) {
1842  return packet_generator_.set_max_packet_length(length);
1843}
1844
1845bool QuicConnection::HasQueuedData() const {
1846  return pending_version_negotiation_packet_ ||
1847      !queued_packets_.empty() || packet_generator_.HasQueuedFrames();
1848}
1849
1850bool QuicConnection::CanWriteStreamData() {
1851  // Don't write stream data if there are negotiation or queued data packets
1852  // to send. Otherwise, continue and bundle as many frames as possible.
1853  if (pending_version_negotiation_packet_ || !queued_packets_.empty()) {
1854    return false;
1855  }
1856
1857  IsHandshake pending_handshake = visitor_->HasPendingHandshake() ?
1858      IS_HANDSHAKE : NOT_HANDSHAKE;
1859  // Sending queued packets may have caused the socket to become write blocked,
1860  // or the congestion manager to prohibit sending.  If we've sent everything
1861  // we had queued and we're still not blocked, let the visitor know it can
1862  // write more.
1863  return ShouldGeneratePacket(NOT_RETRANSMISSION, HAS_RETRANSMITTABLE_DATA,
1864                              pending_handshake);
1865}
1866
1867void QuicConnection::SetIdleNetworkTimeout(QuicTime::Delta timeout) {
1868  if (timeout < idle_network_timeout_) {
1869    idle_network_timeout_ = timeout;
1870    CheckForTimeout();
1871  } else {
1872    idle_network_timeout_ = timeout;
1873  }
1874}
1875
1876void QuicConnection::SetOverallConnectionTimeout(QuicTime::Delta timeout) {
1877  if (timeout < overall_connection_timeout_) {
1878    overall_connection_timeout_ = timeout;
1879    CheckForTimeout();
1880  } else {
1881    overall_connection_timeout_ = timeout;
1882  }
1883}
1884
1885bool QuicConnection::CheckForTimeout() {
1886  QuicTime now = clock_->ApproximateNow();
1887  QuicTime time_of_last_packet = max(time_of_last_received_packet_,
1888                                     time_of_last_sent_new_packet_);
1889
1890  // |delta| can be < 0 as |now| is approximate time but |time_of_last_packet|
1891  // is accurate time. However, this should not change the behavior of
1892  // timeout handling.
1893  QuicTime::Delta delta = now.Subtract(time_of_last_packet);
1894  DVLOG(1) << ENDPOINT << "last packet "
1895           << time_of_last_packet.ToDebuggingValue()
1896           << " now:" << now.ToDebuggingValue()
1897           << " delta:" << delta.ToMicroseconds()
1898           << " network_timeout: " << idle_network_timeout_.ToMicroseconds();
1899  if (delta >= idle_network_timeout_) {
1900    DVLOG(1) << ENDPOINT << "Connection timedout due to no network activity.";
1901    SendConnectionClose(QUIC_CONNECTION_TIMED_OUT);
1902    return true;
1903  }
1904
1905  // Next timeout delta.
1906  QuicTime::Delta timeout = idle_network_timeout_.Subtract(delta);
1907
1908  if (!overall_connection_timeout_.IsInfinite()) {
1909    QuicTime::Delta connected_time =
1910        now.Subtract(stats_.connection_creation_time);
1911    DVLOG(1) << ENDPOINT << "connection time: "
1912             << connected_time.ToMilliseconds() << " overall timeout: "
1913             << overall_connection_timeout_.ToMilliseconds();
1914    if (connected_time >= overall_connection_timeout_) {
1915      DVLOG(1) << ENDPOINT <<
1916          "Connection timedout due to overall connection timeout.";
1917      SendConnectionClose(QUIC_CONNECTION_TIMED_OUT);
1918      return true;
1919    }
1920
1921    // Take the min timeout.
1922    QuicTime::Delta connection_timeout =
1923        overall_connection_timeout_.Subtract(connected_time);
1924    if (connection_timeout < timeout) {
1925      timeout = connection_timeout;
1926    }
1927  }
1928
1929  timeout_alarm_->Cancel();
1930  timeout_alarm_->Set(clock_->ApproximateNow().Add(timeout));
1931  return false;
1932}
1933
1934void QuicConnection::SetPingAlarm() {
1935  if (is_server_) {
1936    // Only clients send pings.
1937    return;
1938  }
1939  ping_alarm_->Cancel();
1940  if (!visitor_->HasOpenDataStreams()) {
1941    // Don't send a ping unless there are open streams.
1942    return;
1943  }
1944  QuicTime::Delta ping_timeout = QuicTime::Delta::FromSeconds(kPingTimeoutSecs);
1945  ping_alarm_->Set(clock_->ApproximateNow().Add(ping_timeout));
1946}
1947
1948QuicConnection::ScopedPacketBundler::ScopedPacketBundler(
1949    QuicConnection* connection,
1950    AckBundling send_ack)
1951    : connection_(connection),
1952      already_in_batch_mode_(connection != NULL &&
1953                             connection->packet_generator_.InBatchMode()) {
1954  if (connection_  == NULL) {
1955    return;
1956  }
1957  // Move generator into batch mode. If caller wants us to include an ack,
1958  // check the delayed-ack timer to see if there's ack info to be sent.
1959  if (!already_in_batch_mode_) {
1960    DVLOG(1) << "Entering Batch Mode.";
1961    connection_->packet_generator_.StartBatchOperations();
1962  }
1963  // Bundle an ack if the alarm is set or with every second packet if we need to
1964  // raise the peer's least unacked.
1965  bool ack_pending =
1966      connection_->ack_alarm_->IsSet() || connection_->stop_waiting_count_ > 1;
1967  if (send_ack == SEND_ACK || (send_ack == BUNDLE_PENDING_ACK && ack_pending)) {
1968    DVLOG(1) << "Bundling ack with outgoing packet.";
1969    connection_->SendAck();
1970  }
1971}
1972
1973QuicConnection::ScopedPacketBundler::~ScopedPacketBundler() {
1974  if (connection_  == NULL) {
1975    return;
1976  }
1977  // If we changed the generator's batch state, restore original batch state.
1978  if (!already_in_batch_mode_) {
1979    DVLOG(1) << "Leaving Batch Mode.";
1980    connection_->packet_generator_.FinishBatchOperations();
1981  }
1982  DCHECK_EQ(already_in_batch_mode_,
1983            connection_->packet_generator_.InBatchMode());
1984}
1985
1986}  // namespace net
1987