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 payload_parity()56 const base::StringPiece payload_parity() const { 57 return base::StringPiece(payload_parity_, payload_parity_len_); 58 } 59 min_protected_packet()60 QuicPacketSequenceNumber min_protected_packet() const { 61 return min_protected_packet_; 62 } 63 NumReceivedPackets()64 size_t NumReceivedPackets() const { 65 return received_packets_.size(); 66 } 67 68 // Returns the effective encryption level of the FEC group. effective_encryption_level()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_ 102