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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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