Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2014 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.h"
      12             : 
      13             : #include "webrtc/base/checks.h"
      14             : 
      15             : namespace webrtc {
      16             : namespace rtcp {
      17             : constexpr size_t RtcpPacket::kHeaderLength;
      18             : 
      19           0 : rtc::Buffer RtcpPacket::Build() const {
      20           0 :   rtc::Buffer packet(BlockLength());
      21             : 
      22           0 :   size_t length = 0;
      23           0 :   bool created = Create(packet.data(), &length, packet.capacity(), nullptr);
      24           0 :   RTC_DCHECK(created) << "Invalid packet is not supported.";
      25           0 :   RTC_DCHECK_EQ(length, packet.size())
      26           0 :       << "BlockLength mispredicted size used by Create";
      27             : 
      28           0 :   return packet;
      29             : }
      30             : 
      31           0 : bool RtcpPacket::BuildExternalBuffer(uint8_t* buffer,
      32             :                                      size_t max_length,
      33             :                                      PacketReadyCallback* callback) const {
      34           0 :   size_t index = 0;
      35           0 :   if (!Create(buffer, &index, max_length, callback))
      36           0 :     return false;
      37           0 :   return OnBufferFull(buffer, &index, callback);
      38             : }
      39             : 
      40           0 : bool RtcpPacket::OnBufferFull(uint8_t* packet,
      41             :                               size_t* index,
      42             :                               PacketReadyCallback* callback) const {
      43           0 :   if (*index == 0)
      44           0 :     return false;
      45           0 :   RTC_DCHECK(callback) << "Fragmentation not supported.";
      46           0 :   callback->OnPacketReady(packet, *index);
      47           0 :   *index = 0;
      48           0 :   return true;
      49             : }
      50             : 
      51           0 : size_t RtcpPacket::HeaderLength() const {
      52           0 :   size_t length_in_bytes = BlockLength();
      53           0 :   RTC_DCHECK_GT(length_in_bytes, 0);
      54           0 :   RTC_DCHECK_EQ(length_in_bytes % 4, 0) << "Padding not supported";
      55             :   // Length in 32-bit words without common header.
      56           0 :   return (length_in_bytes - kHeaderLength) / 4;
      57             : }
      58             : 
      59             : // From RFC 3550, RTP: A Transport Protocol for Real-Time Applications.
      60             : //
      61             : // RTP header format.
      62             : //   0                   1                   2                   3
      63             : //   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
      64             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      65             : //  |V=2|P| RC/FMT  |      PT       |             length            |
      66             : //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      67           0 : void RtcpPacket::CreateHeader(
      68             :     uint8_t count_or_format,  // Depends on packet type.
      69             :     uint8_t packet_type,
      70             :     size_t length,
      71             :     uint8_t* buffer,
      72             :     size_t* pos) {
      73           0 :   RTC_DCHECK_LE(length, 0xffffU);
      74           0 :   RTC_DCHECK_LE(count_or_format, 0x1f);
      75           0 :   constexpr uint8_t kVersionBits = 2 << 6;
      76           0 :   constexpr uint8_t kNoPaddingBit = 0 << 5;
      77           0 :   buffer[*pos + 0] = kVersionBits | kNoPaddingBit | count_or_format;
      78           0 :   buffer[*pos + 1] = packet_type;
      79           0 :   buffer[*pos + 2] = (length >> 8) & 0xff;
      80           0 :   buffer[*pos + 3] = length & 0xff;
      81           0 :   *pos += kHeaderLength;
      82           0 : }
      83             : 
      84             : }  // namespace rtcp
      85             : }  // namespace webrtc