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.
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.
9 #ifndef NET_QUIC_QUIC_FEC_GROUP_H_
10 #define NET_QUIC_QUIC_FEC_GROUP_H_
14 #include "base/strings/string_piece.h"
15 #include "net/quic/quic_protocol.h"
19 class NET_EXPORT_PRIVATE QuicFecGroup {
24 // Updates the FEC group based on the delivery of a data packet.
25 // Returns false if this packet has already been seen, true otherwise.
26 bool Update(const QuicPacketHeader& header,
27 base::StringPiece decrypted_payload);
29 // Updates the FEC group based on the delivery of an FEC packet.
30 // Returns false if this packet has already been seen or if it does
31 // not claim to protect all the packets previously seen in this group.
32 // |fec_packet_entropy|: XOR of entropy of all packets in the fec group.
33 bool UpdateFec(QuicPacketSequenceNumber fec_packet_sequence_number,
34 const QuicFecData& fec);
36 // Returns true if a packet can be revived from this FEC group.
37 bool CanRevive() const;
39 // Returns true if all packets (FEC and data) from this FEC group have been
41 bool IsFinished() const;
43 // Revives the missing packet from this FEC group. This may return a packet
44 // that is null padded to a greater length than the original packet, but
45 // the framer will handle it correctly. Returns the length of the data
46 // written to |decrypted_payload|, or 0 if the packet could not be revived.
47 size_t Revive(QuicPacketHeader* header,
48 char* decrypted_payload,
49 size_t decrypted_payload_len);
51 // Returns true of this FEC group protects any packets with sequence
52 // numbers less than |num|.
53 bool ProtectsPacketsBefore(QuicPacketSequenceNumber num) const;
55 const base::StringPiece payload_parity() const {
56 return base::StringPiece(payload_parity_, payload_parity_len_);
59 QuicPacketSequenceNumber min_protected_packet() const {
60 return min_protected_packet_;
63 size_t NumReceivedPackets() const {
64 return received_packets_.size();
68 bool UpdateParity(base::StringPiece payload);
69 // Returns the number of missing packets, or size_t max if the number
70 // of missing packets is not known.
71 size_t NumMissingPackets() const;
73 // Set of packets that we have recevied.
74 SequenceNumberSet received_packets_;
75 // Sequence number of the first protected packet in this group (the one
76 // with the lowest packet sequence number). Will only be set once the FEC
77 // packet has been seen.
78 QuicPacketSequenceNumber min_protected_packet_;
79 // Sequence number of the last protected packet in this group (the one
80 // with the highest packet sequence number). Will only be set once the FEC
81 // packet has been seen.
82 QuicPacketSequenceNumber max_protected_packet_;
83 // The cumulative parity calculation of all received packets.
84 char payload_parity_[kMaxPacketSize];
85 size_t payload_parity_len_;
87 DISALLOW_COPY_AND_ASSIGN(QuicFecGroup);
92 #endif // NET_QUIC_QUIC_FEC_GROUP_H_