Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
       3             :  *
       4             :  *  Use of this source code is governed by a BSD-style license
       5             :  *  that can be found in the LICENSE file in the root of the source
       6             :  *  tree. An additional intellectual property rights grant can be found
       7             :  *  in the file PATENTS.  All contributing project authors may
       8             :  *  be found in the AUTHORS file in the root of the source tree.
       9             :  */
      10             : 
      11             : #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/fir.h"
      12             : 
      13             : #include "webrtc/base/checks.h"
      14             : #include "webrtc/base/logging.h"
      15             : #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
      16             : #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/common_header.h"
      17             : 
      18             : namespace webrtc {
      19             : namespace rtcp {
      20             : constexpr uint8_t Fir::kFeedbackMessageType;
      21             : // RFC 4585: Feedback format.
      22             : // Common packet format:
      23             : //
      24             : //   0                   1                   2                   3
      25             : //   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      26             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      27             : //  |V=2|P|   FMT   |       PT      |          length               |
      28             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      29             : //  |                  SSRC of packet sender                        |
      30             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      31             : //  |             SSRC of media source (unused) = 0                 |
      32             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      33             : //  :            Feedback Control Information (FCI)                 :
      34             : //  :                                                               :
      35             : // Full intra request (FIR) (RFC 5104).
      36             : // The Feedback Control Information (FCI) for the Full Intra Request
      37             : // consists of one or more FCI entries.
      38             : // FCI:
      39             : //   0                   1                   2                   3
      40             : //   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      41             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      42             : //  |                              SSRC                             |
      43             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      44             : //  | Seq nr.       |    Reserved = 0                               |
      45             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      46           0 : bool Fir::Parse(const CommonHeader& packet) {
      47           0 :   RTC_DCHECK_EQ(packet.type(), kPacketType);
      48           0 :   RTC_DCHECK_EQ(packet.fmt(), kFeedbackMessageType);
      49             : 
      50             :   // The FCI field MUST contain one or more FIR entries.
      51           0 :   if (packet.payload_size_bytes() < kCommonFeedbackLength + kFciLength) {
      52           0 :     LOG(LS_WARNING) << "Packet is too small to be a valid FIR packet.";
      53           0 :     return false;
      54             :   }
      55             : 
      56           0 :   if ((packet.payload_size_bytes() - kCommonFeedbackLength) % kFciLength != 0) {
      57           0 :     LOG(LS_WARNING) << "Invalid size for a valid FIR packet.";
      58           0 :     return false;
      59             :   }
      60             : 
      61           0 :   ParseCommonFeedback(packet.payload());
      62             : 
      63             :   size_t number_of_fci_items =
      64           0 :       (packet.payload_size_bytes() - kCommonFeedbackLength) / kFciLength;
      65           0 :   const uint8_t* next_fci = packet.payload() + kCommonFeedbackLength;
      66           0 :   items_.resize(number_of_fci_items);
      67           0 :   for (Request& request : items_) {
      68           0 :     request.ssrc = ByteReader<uint32_t>::ReadBigEndian(next_fci);
      69           0 :     request.seq_nr = ByteReader<uint8_t>::ReadBigEndian(next_fci + 4);
      70           0 :     next_fci += kFciLength;
      71             :   }
      72           0 :   return true;
      73             : }
      74             : 
      75           0 : bool Fir::Create(uint8_t* packet,
      76             :                  size_t* index,
      77             :                  size_t max_length,
      78             :                  RtcpPacket::PacketReadyCallback* callback) const {
      79           0 :   RTC_DCHECK(!items_.empty());
      80           0 :   while (*index + BlockLength() > max_length) {
      81           0 :     if (!OnBufferFull(packet, index, callback))
      82           0 :       return false;
      83             :   }
      84           0 :   size_t index_end = *index + BlockLength();
      85           0 :   CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet,
      86           0 :                index);
      87           0 :   RTC_DCHECK_EQ(Psfb::media_ssrc(), 0);
      88           0 :   CreateCommonFeedback(packet + *index);
      89           0 :   *index += kCommonFeedbackLength;
      90             : 
      91           0 :   constexpr uint32_t kReserved = 0;
      92           0 :   for (const Request& request : items_) {
      93           0 :     ByteWriter<uint32_t>::WriteBigEndian(packet + *index, request.ssrc);
      94           0 :     ByteWriter<uint8_t>::WriteBigEndian(packet + *index + 4, request.seq_nr);
      95           0 :     ByteWriter<uint32_t, 3>::WriteBigEndian(packet + *index + 5, kReserved);
      96           0 :     *index += kFciLength;
      97             :   }
      98           0 :   RTC_CHECK_EQ(*index, index_end);
      99           0 :   return true;
     100             : }
     101             : }  // namespace rtcp
     102             : }  // namespace webrtc