net/quic/quic_time_wait_list_manager.cc

   1 // Copyright 2014 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_time_wait_list_manager.h"
   6
   7 #include <errno.h>
   8
   9 #include "base/containers/hash_tables.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/stl_util.h"
  12 #include "net/base/ip_endpoint.h"
  13 #include "net/quic/crypto/crypto_protocol.h"
  14 #include "net/quic/crypto/quic_decrypter.h"
  15 #include "net/quic/crypto/quic_encrypter.h"
  16 #include "net/quic/quic_clock.h"
  17 #include "net/quic/quic_connection_helper.h"
  18 #include "net/quic/quic_flags.h"
  19 #include "net/quic/quic_framer.h"
  20 #include "net/quic/quic_protocol.h"
  21 #include "net/quic/quic_server_session.h"
  22 #include "net/quic/quic_utils.h"
  23
  24 using base::StringPiece;
  25
  26 namespace net {
  27
  28 // A very simple alarm that just informs the QuicTimeWaitListManager to clean
  29 // up old connection_ids. This alarm should be unregistered and deleted before
  30 // the QuicTimeWaitListManager is deleted.
  31 class ConnectionIdCleanUpAlarm : public QuicAlarm::Delegate {
  32  public:
  33   explicit ConnectionIdCleanUpAlarm(
  34       QuicTimeWaitListManager* time_wait_list_manager)
  35       : time_wait_list_manager_(time_wait_list_manager) {
  36   }
  37
  38   QuicTime OnAlarm() override {
  39     time_wait_list_manager_->CleanUpOldConnectionIds();
  40     // Let the time wait manager register the alarm at appropriate time.
  41     return QuicTime::Zero();
  42   }
  43
  44  private:
  45   // Not owned.
  46   QuicTimeWaitListManager* time_wait_list_manager_;
  47 };
  48
  49 // This class stores pending public reset packets to be sent to clients.
  50 // server_address - server address on which a packet what was received for
  51 //                  a connection_id in time wait state.
  52 // client_address - address of the client that sent that packet. Needed to send
  53 //                  the public reset packet back to the client.
  54 // packet - the pending public reset packet that is to be sent to the client.
  55 //          created instance takes the ownership of this packet.
  56 class QuicTimeWaitListManager::QueuedPacket {
  57  public:
  58   QueuedPacket(const IPEndPoint& server_address,
  59                const IPEndPoint& client_address,
  60                QuicEncryptedPacket* packet)
  61       : server_address_(server_address),
  62         client_address_(client_address),
  63         packet_(packet) {
  64   }
  65
  66   const IPEndPoint& server_address() const { return server_address_; }
  67   const IPEndPoint& client_address() const { return client_address_; }
  68   QuicEncryptedPacket* packet() { return packet_.get(); }
  69
  70  private:
  71   const IPEndPoint server_address_;
  72   const IPEndPoint client_address_;
  73   scoped_ptr<QuicEncryptedPacket> packet_;
  74
  75   DISALLOW_COPY_AND_ASSIGN(QueuedPacket);
  76 };
  77
  78 QuicTimeWaitListManager::QuicTimeWaitListManager(
  79     QuicPacketWriter* writer,
  80     QuicServerSessionVisitor* visitor,
  81     QuicConnectionHelperInterface* helper,
  82     const QuicVersionVector& supported_versions)
  83     : helper_(helper),
  84       time_wait_period_(
  85           QuicTime::Delta::FromSeconds(FLAGS_quic_time_wait_list_seconds)),
  86       connection_id_clean_up_alarm_(
  87           helper_->CreateAlarm(new ConnectionIdCleanUpAlarm(this))),
  88       writer_(writer),
  89       visitor_(visitor) {
  90   SetConnectionIdCleanUpAlarm();
  91 }
  92
  93 QuicTimeWaitListManager::~QuicTimeWaitListManager() {
  94   connection_id_clean_up_alarm_->Cancel();
  95   STLDeleteElements(&pending_packets_queue_);
  96   for (ConnectionIdMap::iterator it = connection_id_map_.begin();
  97        it != connection_id_map_.end();
  98        ++it) {
  99     delete it->second.close_packet;
 100   }
 101 }
 102
 103 void QuicTimeWaitListManager::AddConnectionIdToTimeWait(
 104     QuicConnectionId connection_id,
 105     QuicVersion version,
 106     QuicEncryptedPacket* close_packet) {
 107   int num_packets = 0;
 108   ConnectionIdMap::iterator it = connection_id_map_.find(connection_id);
 109   const bool new_connection_id = it == connection_id_map_.end();
 110   if (!new_connection_id) {  // Replace record if it is reinserted.
 111     num_packets = it->second.num_packets;
 112     delete it->second.close_packet;
 113     connection_id_map_.erase(it);
 114   }
 115   TrimTimeWaitListIfNeeded();
 116   DCHECK_LT(num_connections(),
 117             static_cast<size_t>(FLAGS_quic_time_wait_list_max_connections));
 118   ConnectionIdData data(num_packets,
 119                         version,
 120                         helper_->GetClock()->ApproximateNow(),
 121                         close_packet);
 122   connection_id_map_.insert(std::make_pair(connection_id, data));
 123   if (new_connection_id) {
 124     visitor_->OnConnectionAddedToTimeWaitList(connection_id);
 125   }
 126 }
 127
 128 bool QuicTimeWaitListManager::IsConnectionIdInTimeWait(
 129     QuicConnectionId connection_id) const {
 130   return ContainsKey(connection_id_map_, connection_id);
 131 }
 132
 133 QuicVersion QuicTimeWaitListManager::GetQuicVersionFromConnectionId(
 134     QuicConnectionId connection_id) {
 135   ConnectionIdMap::iterator it = connection_id_map_.find(connection_id);
 136   DCHECK(it != connection_id_map_.end());
 137   return (it->second).version;
 138 }
 139
 140 void QuicTimeWaitListManager::OnCanWrite() {
 141   while (!pending_packets_queue_.empty()) {
 142     QueuedPacket* queued_packet = pending_packets_queue_.front();
 143     if (!WriteToWire(queued_packet)) {
 144       return;
 145     }
 146     pending_packets_queue_.pop_front();
 147     delete queued_packet;
 148   }
 149 }
 150
 151 void QuicTimeWaitListManager::ProcessPacket(
 152     const IPEndPoint& server_address,
 153     const IPEndPoint& client_address,
 154     QuicConnectionId connection_id,
 155     QuicPacketSequenceNumber sequence_number,
 156     const QuicEncryptedPacket& /*packet*/) {
 157   DCHECK(IsConnectionIdInTimeWait(connection_id));
 158   DVLOG(1) << "Processing " << connection_id << " in time wait state.";
 159   // TODO(satyamshekhar): Think about handling packets from different client
 160   // addresses.
 161   ConnectionIdMap::iterator it = connection_id_map_.find(connection_id);
 162   DCHECK(it != connection_id_map_.end());
 163   // Increment the received packet count.
 164   ++((it->second).num_packets);
 165   if (!ShouldSendResponse((it->second).num_packets)) {
 166     return;
 167   }
 168   if (it->second.close_packet) {
 169     QueuedPacket* queued_packet =
 170         new QueuedPacket(server_address,
 171                          client_address,
 172                          it->second.close_packet->Clone());
 173     // Takes ownership of the packet.
 174     SendOrQueuePacket(queued_packet);
 175   } else {
 176     SendPublicReset(server_address,
 177                     client_address,
 178                     connection_id,
 179                     sequence_number);
 180   }
 181 }
 182
 183 // Returns true if the number of packets received for this connection_id is a
 184 // power of 2 to throttle the number of public reset packets we send to a
 185 // client.
 186 bool QuicTimeWaitListManager::ShouldSendResponse(int received_packet_count) {
 187   return (received_packet_count & (received_packet_count - 1)) == 0;
 188 }
 189
 190 void QuicTimeWaitListManager::SendPublicReset(
 191     const IPEndPoint& server_address,
 192     const IPEndPoint& client_address,
 193     QuicConnectionId connection_id,
 194     QuicPacketSequenceNumber rejected_sequence_number) {
 195   QuicPublicResetPacket packet;
 196   packet.public_header.connection_id = connection_id;
 197   packet.public_header.reset_flag = true;
 198   packet.public_header.version_flag = false;
 199   packet.rejected_sequence_number = rejected_sequence_number;
 200   // TODO(satyamshekhar): generate a valid nonce for this connection_id.
 201   packet.nonce_proof = 1010101;
 202   packet.client_address = client_address;
 203   QueuedPacket* queued_packet = new QueuedPacket(
 204       server_address,
 205       client_address,
 206       BuildPublicReset(packet));
 207   // Takes ownership of the packet.
 208   SendOrQueuePacket(queued_packet);
 209 }
 210
 211 QuicEncryptedPacket* QuicTimeWaitListManager::BuildPublicReset(
 212     const QuicPublicResetPacket& packet) {
 213   return QuicFramer::BuildPublicResetPacket(packet);
 214 }
 215
 216 // Either sends the packet and deletes it or makes pending queue the
 217 // owner of the packet.
 218 void QuicTimeWaitListManager::SendOrQueuePacket(QueuedPacket* packet) {
 219   if (WriteToWire(packet)) {
 220     delete packet;
 221   } else {
 222     // pending_packets_queue takes the ownership of the queued packet.
 223     pending_packets_queue_.push_back(packet);
 224   }
 225 }
 226
 227 bool QuicTimeWaitListManager::WriteToWire(QueuedPacket* queued_packet) {
 228   if (writer_->IsWriteBlocked()) {
 229     visitor_->OnWriteBlocked(this);
 230     return false;
 231   }
 232   WriteResult result = writer_->WritePacket(
 233       queued_packet->packet()->data(),
 234       queued_packet->packet()->length(),
 235       queued_packet->server_address().address(),
 236       queued_packet->client_address());
 237   if (result.status == WRITE_STATUS_BLOCKED) {
 238     // If blocked and unbuffered, return false to retry sending.
 239     DCHECK(writer_->IsWriteBlocked());
 240     visitor_->OnWriteBlocked(this);
 241     return writer_->IsWriteBlockedDataBuffered();
 242   } else if (result.status == WRITE_STATUS_ERROR) {
 243     LOG(WARNING) << "Received unknown error while sending reset packet to "
 244                  << queued_packet->client_address().ToString() << ": "
 245                  << strerror(result.error_code);
 246   }
 247   return true;
 248 }
 249
 250 void QuicTimeWaitListManager::SetConnectionIdCleanUpAlarm() {
 251   connection_id_clean_up_alarm_->Cancel();
 252   QuicTime now = helper_->GetClock()->ApproximateNow();
 253   QuicTime next_alarm_time = now;
 254   if (!connection_id_map_.empty()) {
 255     QuicTime oldest_connection_id =
 256         connection_id_map_.begin()->second.time_added;
 257     if (now.Subtract(oldest_connection_id) < time_wait_period_) {
 258       next_alarm_time = oldest_connection_id.Add(time_wait_period_);
 259     } else {
 260       LOG(ERROR) << "ConnectionId lingered for longer than kTimeWaitPeriod";
 261     }
 262   } else {
 263     // No connection_ids added so none will expire before time_wait_period_.
 264     next_alarm_time = now.Add(time_wait_period_);
 265   }
 266
 267   connection_id_clean_up_alarm_->Set(next_alarm_time);
 268 }
 269
 270 bool QuicTimeWaitListManager::MaybeExpireOldestConnection(
 271     QuicTime expiration_time) {
 272   if (connection_id_map_.empty()) {
 273     return false;
 274   }
 275   ConnectionIdMap::iterator it = connection_id_map_.begin();
 276   QuicTime oldest_connection_id_time = it->second.time_added;
 277   if (oldest_connection_id_time > expiration_time) {
 278     // Too recent, don't retire.
 279     return false;
 280   }
 281   // This connection_id has lived its age, retire it now.
 282   const QuicConnectionId connection_id = it->first;
 283   delete it->second.close_packet;
 284   connection_id_map_.erase(it);
 285   visitor_->OnConnectionRemovedFromTimeWaitList(connection_id);
 286   return true;
 287 }
 288
 289 void QuicTimeWaitListManager::CleanUpOldConnectionIds() {
 290   QuicTime now = helper_->GetClock()->ApproximateNow();
 291   QuicTime expiration = now.Subtract(time_wait_period_);
 292
 293   while (MaybeExpireOldestConnection(expiration)) {
 294   }
 295
 296   SetConnectionIdCleanUpAlarm();
 297 }
 298
 299 void QuicTimeWaitListManager::TrimTimeWaitListIfNeeded() {
 300   if (FLAGS_quic_time_wait_list_max_connections < 0) {
 301     return;
 302   }
 303   while (num_connections() >=
 304          static_cast<size_t>(FLAGS_quic_time_wait_list_max_connections)) {
 305     MaybeExpireOldestConnection(QuicTime::Infinite());
 306   }
 307 }
 308
 309 }  // namespace net