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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 <deque> | |
12 | |
13 #include "net/base/linked_hash_map.h" | |
14 #include "net/quic/quic_framer.h" | |
15 #include "net/quic/quic_protocol.h" | |
16 | |
17 namespace net { | |
18 | |
19 namespace test { | |
20 class QuicConnectionPeer; | |
21 } // namespace test | |
22 | |
23 // Records all sent packets by a connection to track the cumulative entropy of | |
24 // sent packets. It is used by the connection to validate an ack | |
25 // frame sent by the peer as a preventive measure against the optimistic ack | |
26 // attack. | |
27 class NET_EXPORT_PRIVATE QuicSentEntropyManager { | |
28 public: | |
29 QuicSentEntropyManager(); | |
30 virtual ~QuicSentEntropyManager(); | |
31 | |
32 // Record |entropy_hash| for sent packet corresponding to |sequence_number|. | |
33 void RecordPacketEntropyHash(QuicPacketSequenceNumber sequence_number, | |
34 QuicPacketEntropyHash entropy_hash); | |
35 | |
36 // Retrieves the cumulative entropy up to |sequence_number|. | |
37 // Must always be called with a monotonically increasing |sequence_number|. | |
38 QuicPacketEntropyHash GetCumulativeEntropy( | |
39 QuicPacketSequenceNumber sequence_number); | |
40 | |
41 // Returns true if |entropy_hash| matches the expected sent entropy hash | |
42 // up to |largest_observed| removing sequence numbers from |missing_packets|. | |
43 // Must always be called with a monotonically increasing |largest_observed|. | |
44 bool IsValidEntropy(QuicPacketSequenceNumber largest_observed, | |
45 const SequenceNumberSet& missing_packets, | |
46 QuicPacketEntropyHash entropy_hash); | |
47 | |
48 // Removes unnecessary entries before |sequence_number|. | |
49 void ClearEntropyBefore(QuicPacketSequenceNumber sequence_number); | |
50 | |
51 private: | |
52 friend class test::QuicConnectionPeer; | |
53 | |
54 typedef std::deque<QuicPacketEntropyHash> SentEntropyMap; | |
55 | |
56 struct CumulativeEntropy { | |
57 CumulativeEntropy() : sequence_number(0), entropy(0) {} | |
58 | |
59 QuicPacketSequenceNumber sequence_number; | |
60 QuicPacketEntropyHash entropy; | |
61 }; | |
62 | |
63 // Convenience methods to get the largest and smallest packets with entropies. | |
64 QuicPacketSequenceNumber GetLargestPacketWithEntropy() const; | |
65 QuicPacketSequenceNumber GetSmallestPacketWithEntropy() const; | |
66 // Convenience method to get the entropy hash for |sequence_number|. | |
67 QuicPacketEntropyHash GetPacketEntropy( | |
68 QuicPacketSequenceNumber sequence_number) const; | |
69 | |
70 // Update the cumulative entropy to |sequence_number|. | |
71 void UpdateCumulativeEntropy(QuicPacketSequenceNumber sequence_number, | |
72 CumulativeEntropy* cumulative) const; | |
73 | |
74 // Maps sequence numbers to the sent entropy hash for the sequence number. | |
75 SentEntropyMap packets_entropy_; | |
76 QuicPacketSequenceNumber map_offset_; | |
77 | |
78 // Cache the cumulative entropy for IsValidEntropy. | |
79 CumulativeEntropy last_valid_entropy_; | |
80 | |
81 // Cache the cumulative entropy for the sequence number used by EntropyHash. | |
82 CumulativeEntropy last_cumulative_entropy_; | |
83 | |
84 DISALLOW_COPY_AND_ASSIGN(QuicSentEntropyManager); | |
85 }; | |
86 | |
87 } // namespace net | |
88 | |
89 #endif // NET_QUIC_QUIC_SENT_ENTROPY_MANAGER_H_ | |
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