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