net/quic/quic_sent_entropy_manager.cc

   1 // Copyright 2013 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_sent_entropy_manager.h"
   6
   7 #include "base/logging.h"
   8 #include "net/base/linked_hash_map.h"
   9
  10 using std::make_pair;
  11 using std::max;
  12 using std::min;
  13
  14 namespace net {
  15
  16 QuicSentEntropyManager::QuicSentEntropyManager()
  17     : packets_entropy_hash_(0) {}
  18
  19 QuicSentEntropyManager::~QuicSentEntropyManager() {}
  20
  21 void QuicSentEntropyManager::RecordPacketEntropyHash(
  22     QuicPacketSequenceNumber sequence_number,
  23     QuicPacketEntropyHash entropy_hash) {
  24   // TODO(satyamshekhar): Check this logic again when/if we enable packet
  25   // reordering.
  26   packets_entropy_hash_ ^= entropy_hash;
  27   packets_entropy_.insert(
  28       make_pair(sequence_number,
  29                 make_pair(entropy_hash, packets_entropy_hash_)));
  30   DVLOG(2) << "setting cumulative sent entropy hash to: "
  31            << static_cast<int>(packets_entropy_hash_)
  32            << " updated with sequence number " << sequence_number
  33            << " entropy hash: " << static_cast<int>(entropy_hash);
  34 }
  35
  36 QuicPacketEntropyHash QuicSentEntropyManager::EntropyHash(
  37     QuicPacketSequenceNumber sequence_number) const {
  38   SentEntropyMap::const_iterator it =
  39       packets_entropy_.find(sequence_number);
  40   if (it == packets_entropy_.end()) {
  41     // Should only happen when we have not received ack for any packet.
  42     DCHECK_EQ(0u, sequence_number);
  43     return 0;
  44   }
  45   return it->second.second;
  46 }
  47
  48 bool QuicSentEntropyManager::IsValidEntropy(
  49     QuicPacketSequenceNumber sequence_number,
  50     const SequenceNumberSet& missing_packets,
  51     QuicPacketEntropyHash entropy_hash) const {
  52   SentEntropyMap::const_iterator entropy_it =
  53       packets_entropy_.find(sequence_number);
  54   if (entropy_it == packets_entropy_.end()) {
  55     DCHECK_EQ(0u, sequence_number);
  56     // Close connection if something goes wrong.
  57     return 0 == sequence_number;
  58   }
  59   QuicPacketEntropyHash expected_entropy_hash = entropy_it->second.second;
  60   for (SequenceNumberSet::const_iterator it = missing_packets.begin();
  61        it != missing_packets.end(); ++it) {
  62     entropy_it = packets_entropy_.find(*it);
  63     DCHECK(entropy_it != packets_entropy_.end());
  64     expected_entropy_hash ^= entropy_it->second.first;
  65   }
  66   DLOG_IF(WARNING, entropy_hash != expected_entropy_hash)
  67       << "Invalid entropy hash: " << static_cast<int>(entropy_hash)
  68       << " expected entropy hash: " << static_cast<int>(expected_entropy_hash);
  69   return entropy_hash == expected_entropy_hash;
  70 }
  71
  72 void QuicSentEntropyManager::ClearEntropyBefore(
  73     QuicPacketSequenceNumber sequence_number) {
  74   if (packets_entropy_.empty()) {
  75     return;
  76   }
  77   SentEntropyMap::iterator it = packets_entropy_.begin();
  78   while (it->first < sequence_number) {
  79     packets_entropy_.erase(it);
  80     it = packets_entropy_.begin();
  81     DCHECK(it != packets_entropy_.end());
  82   }
  83   DVLOG(2) << "Cleared entropy before: "
  84            << packets_entropy_.begin()->first;
  85 }
  86
  87 }  // namespace net