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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Tracks information about an FEC group, including the packets
// that have been seen, and the running parity. Provided the ability
// to revive a dropped packet.
#ifndef NET_QUIC_QUIC_FEC_GROUP_H_
#define NET_QUIC_QUIC_FEC_GROUP_H_
#include <set>
#include "base/strings/string_piece.h"
#include "net/quic/quic_protocol.h"
namespace net {
class NET_EXPORT_PRIVATE QuicFecGroup {
public:
QuicFecGroup();
~QuicFecGroup();
// Updates the FEC group based on the delivery of a data packet.
// Returns false if this packet has already been seen, true otherwise.
bool Update(const QuicPacketHeader& header,
base::StringPiece decrypted_payload);
// Updates the FEC group based on the delivery of an FEC packet.
// Returns false if this packet has already been seen or if it does
// not claim to protect all the packets previously seen in this group.
// |fec_packet_entropy|: XOR of entropy of all packets in the fec group.
bool UpdateFec(QuicPacketSequenceNumber fec_packet_sequence_number,
bool fec_packet_entropy,
const QuicFecData& fec);
// Returns true if a packet can be revived from this FEC group.
bool CanRevive() const;
// Returns true if all packets (FEC and data) from this FEC group have been
// seen or revived
bool IsFinished() const;
// Revives the missing packet from this FEC group. This may return a packet
// that is null padded to a greater length than the original packet, but
// the framer will handle it correctly. Returns the length of the data
// written to |decrypted_payload|, or 0 if the packet could not be revived.
size_t Revive(QuicPacketHeader* header,
char* decrypted_payload,
size_t decrypted_payload_len);
// Returns true of this FEC group protects any packets with sequence
// numbers less than |num|.
bool ProtectsPacketsBefore(QuicPacketSequenceNumber num) const;
const base::StringPiece payload_parity() const {
return base::StringPiece(payload_parity_, payload_parity_len_);
}
bool entropy_parity() const {
return entropy_parity_;
}
QuicPacketSequenceNumber min_protected_packet() const {
return min_protected_packet_;
}
size_t NumReceivedPackets() const {
return received_packets_.size();
}
private:
bool UpdateParity(base::StringPiece payload, bool entropy);
// Returns the number of missing packets, or size_t max if the number
// of missing packets is not known.
size_t NumMissingPackets() const;
// Set of packets that we have recevied.
SequenceNumberSet received_packets_;
// Sequence number of the first protected packet in this group (the one
// with the lowest packet sequence number). Will only be set once the FEC
// packet has been seen.
QuicPacketSequenceNumber min_protected_packet_;
// Sequence number of the last protected packet in this group (the one
// with the highest packet sequence number). Will only be set once the FEC
// packet has been seen.
QuicPacketSequenceNumber max_protected_packet_;
// The cumulative parity calculation of all received packets.
char payload_parity_[kMaxPacketSize];
size_t payload_parity_len_;
bool entropy_parity_;
DISALLOW_COPY_AND_ASSIGN(QuicFecGroup);
};
} // namespace net
#endif // NET_QUIC_QUIC_FEC_GROUP_H_
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