net/quic/quic_sent_entropy_manager.h

   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 // Manages the packet entropy calculation for both sent and received packets
   6 // for a connection.
   7
   8 #ifndef NET_QUIC_QUIC_SENT_ENTROPY_MANAGER_H_
   9 #define NET_QUIC_QUIC_SENT_ENTROPY_MANAGER_H_
  10
  11 #include "net/base/linked_hash_map.h"
  12 #include "net/quic/quic_framer.h"
  13 #include "net/quic/quic_protocol.h"
  14
  15 namespace net {
  16
  17 // Records all sent packets by a connection to track the cumulative entropy of
  18 // sent packets.  It is used by the connection to validate an ack
  19 // frame sent by the peer as a preventive measure against the optimistic ack
  20 // attack.
  21 class NET_EXPORT_PRIVATE QuicSentEntropyManager {
  22  public:
  23   QuicSentEntropyManager();
  24   virtual ~QuicSentEntropyManager();
  25
  26   // Record |entropy_hash| for sent packet corresponding to |sequence_number|.
  27   void RecordPacketEntropyHash(QuicPacketSequenceNumber sequence_number,
  28                                QuicPacketEntropyHash entropy_hash);
  29
  30   QuicPacketEntropyHash EntropyHash(
  31       QuicPacketSequenceNumber sequence_number) const;
  32
  33   // Returns true if |entropy_hash| matches the expected sent entropy hash
  34   // up to |sequence_number| removing sequence numbers from |missing_packets|.
  35   bool IsValidEntropy(QuicPacketSequenceNumber sequence_number,
  36                       const SequenceNumberSet& missing_packets,
  37                       QuicPacketEntropyHash entropy_hash) const;
  38
  39   // Removes not required entries from |packets_entropy_| before
  40   // |sequence_number|.
  41   void ClearEntropyBefore(QuicPacketSequenceNumber sequence_number);
  42
  43  private:
  44   typedef linked_hash_map<QuicPacketSequenceNumber,
  45                           std::pair<QuicPacketEntropyHash,
  46                                QuicPacketEntropyHash> > SentEntropyMap;
  47
  48   // Linked hash map from sequence numbers to the sent entropy hash up to the
  49   // sequence number in the key.
  50   SentEntropyMap packets_entropy_;
  51
  52   // Cumulative hash of entropy of all sent packets.
  53   QuicPacketEntropyHash packets_entropy_hash_;
  54
  55   DISALLOW_COPY_AND_ASSIGN(QuicSentEntropyManager);
  56 };
  57
  58 }  // namespace net
  59
  60 #endif  // NET_QUIC_QUIC_SENT_ENTROPY_MANAGER_H_