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1 // Copyright (c) 2012 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 // Tracks information about an FEC group, including the packets | |
6 // that have been seen, and the running parity. Provided the ability | |
7 // to revive a dropped packet. | |
8 | |
9 #ifndef NET_QUIC_QUIC_FEC_GROUP_H_ | |
10 #define NET_QUIC_QUIC_FEC_GROUP_H_ | |
11 | |
12 #include "base/strings/string_piece.h" | |
13 #include "net/quic/quic_protocol.h" | |
14 | |
15 namespace net { | |
16 | |
17 class NET_EXPORT_PRIVATE QuicFecGroup { | |
18 public: | |
19 QuicFecGroup(); | |
20 ~QuicFecGroup(); | |
21 | |
22 // Updates the FEC group based on the delivery of a data packet decrypted at | |
23 // |encryption_level|. Returns false if this packet has already been seen, | |
24 // true otherwise. | |
25 bool Update(EncryptionLevel encryption_level, | |
26 const QuicPacketHeader& header, | |
27 base::StringPiece decrypted_payload); | |
28 | |
29 // Updates the FEC group based on the delivery of an FEC packet decrypted at | |
30 // |encryption_level|. Returns false if this packet has already been seen or | |
31 // if it does not claim to protect all the packets previously seen in this | |
32 // group. | |
33 bool UpdateFec(EncryptionLevel encryption_level, | |
34 QuicPacketSequenceNumber fec_packet_sequence_number, | |
35 const QuicFecData& fec); | |
36 | |
37 // Returns true if a packet can be revived from this FEC group. | |
38 bool CanRevive() const; | |
39 | |
40 // Returns true if all packets (FEC and data) from this FEC group have been | |
41 // seen or revived | |
42 bool IsFinished() const; | |
43 | |
44 // Revives the missing packet from this FEC group. This may return a packet | |
45 // that is null padded to a greater length than the original packet, but | |
46 // the framer will handle it correctly. Returns the length of the data | |
47 // written to |decrypted_payload|, or 0 if the packet could not be revived. | |
48 size_t Revive(QuicPacketHeader* header, | |
49 char* decrypted_payload, | |
50 size_t decrypted_payload_len); | |
51 | |
52 // Returns true of this FEC group protects any packets with sequence | |
53 // numbers less than |num|. | |
54 bool ProtectsPacketsBefore(QuicPacketSequenceNumber num) const; | |
55 | |
56 const base::StringPiece payload_parity() const { | |
57 return base::StringPiece(payload_parity_, payload_parity_len_); | |
58 } | |
59 | |
60 QuicPacketSequenceNumber min_protected_packet() const { | |
61 return min_protected_packet_; | |
62 } | |
63 | |
64 size_t NumReceivedPackets() const { | |
65 return received_packets_.size(); | |
66 } | |
67 | |
68 // Returns the effective encryption level of the FEC group. | |
69 EncryptionLevel effective_encryption_level() const { | |
70 return effective_encryption_level_; | |
71 } | |
72 | |
73 private: | |
74 bool UpdateParity(base::StringPiece payload); | |
75 // Returns the number of missing packets, or size_t max if the number | |
76 // of missing packets is not known. | |
77 size_t NumMissingPackets() const; | |
78 | |
79 // Set of packets that we have recevied. | |
80 SequenceNumberSet received_packets_; | |
81 // Sequence number of the first protected packet in this group (the one | |
82 // with the lowest packet sequence number). Will only be set once the FEC | |
83 // packet has been seen. | |
84 QuicPacketSequenceNumber min_protected_packet_; | |
85 // Sequence number of the last protected packet in this group (the one | |
86 // with the highest packet sequence number). Will only be set once the FEC | |
87 // packet has been seen. | |
88 QuicPacketSequenceNumber max_protected_packet_; | |
89 // The cumulative parity calculation of all received packets. | |
90 char payload_parity_[kMaxPacketSize]; | |
91 size_t payload_parity_len_; | |
92 // The effective encryption level, which is the lowest encryption level of | |
93 // the data and FEC in the group. | |
94 EncryptionLevel effective_encryption_level_; | |
95 | |
96 DISALLOW_COPY_AND_ASSIGN(QuicFecGroup); | |
97 }; | |
98 | |
99 } // namespace net | |
100 | |
101 #endif // NET_QUIC_QUIC_FEC_GROUP_H_ | |
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