1 /*
2 * Copyright (c) 2015 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/bye.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
17 using webrtc::RTCPUtility::RtcpCommonHeader;
18
19 namespace webrtc {
20 namespace rtcp {
21
22 // Bye packet (BYE) (RFC 3550).
23 //
24 // 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
25 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
26 // |V=2|P| SC | PT=BYE=203 | length |
27 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
28 // | SSRC/CSRC |
29 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
30 // : ... :
31 // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
32 // (opt) | length | reason for leaving ...
33 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Bye()34 Bye::Bye() : sender_ssrc_(0) {}
35
Parse(const RtcpCommonHeader & header,const uint8_t * payload)36 bool Bye::Parse(const RtcpCommonHeader& header, const uint8_t* payload) {
37 RTC_DCHECK(header.packet_type == kPacketType);
38
39 const uint8_t src_count = header.count_or_format;
40 // Validate packet.
41 if (header.payload_size_bytes < 4u * src_count) {
42 LOG(LS_WARNING)
43 << "Packet is too small to contain CSRCs it promise to have.";
44 return false;
45 }
46 bool has_reason = (header.payload_size_bytes > 4u * src_count);
47 uint8_t reason_length = 0;
48 if (has_reason) {
49 reason_length = payload[4u * src_count];
50 if (header.payload_size_bytes - 4u * src_count < 1u + reason_length) {
51 LOG(LS_WARNING) << "Invalid reason length: " << reason_length;
52 return false;
53 }
54 }
55 // Once sure packet is valid, copy values.
56 if (src_count == 0) { // A count value of zero is valid, but useless.
57 sender_ssrc_ = 0;
58 csrcs_.clear();
59 } else {
60 sender_ssrc_ = ByteReader<uint32_t>::ReadBigEndian(payload);
61 csrcs_.resize(src_count - 1);
62 for (size_t i = 1; i < src_count; ++i)
63 csrcs_[i - 1] = ByteReader<uint32_t>::ReadBigEndian(&payload[4 * i]);
64 }
65
66 if (has_reason) {
67 reason_.assign(reinterpret_cast<const char*>(&payload[4u * src_count + 1]),
68 reason_length);
69 } else {
70 reason_.clear();
71 }
72
73 return true;
74 }
75
Create(uint8_t * packet,size_t * index,size_t max_length,RtcpPacket::PacketReadyCallback * callback) const76 bool Bye::Create(uint8_t* packet,
77 size_t* index,
78 size_t max_length,
79 RtcpPacket::PacketReadyCallback* callback) const {
80 while (*index + BlockLength() > max_length) {
81 if (!OnBufferFull(packet, index, callback))
82 return false;
83 }
84 const size_t index_end = *index + BlockLength();
85
86 CreateHeader(1 + csrcs_.size(), kPacketType, HeaderLength(), packet, index);
87 // Store srcs of the leaving clients.
88 ByteWriter<uint32_t>::WriteBigEndian(&packet[*index], sender_ssrc_);
89 *index += sizeof(uint32_t);
90 for (uint32_t csrc : csrcs_) {
91 ByteWriter<uint32_t>::WriteBigEndian(&packet[*index], csrc);
92 *index += sizeof(uint32_t);
93 }
94 // Store the reason to leave.
95 if (!reason_.empty()) {
96 uint8_t reason_length = reason_.size();
97 packet[(*index)++] = reason_length;
98 memcpy(&packet[*index], reason_.data(), reason_length);
99 *index += reason_length;
100 // Add padding bytes if needed.
101 size_t bytes_to_pad = index_end - *index;
102 RTC_DCHECK_LE(bytes_to_pad, 3u);
103 if (bytes_to_pad > 0) {
104 memset(&packet[*index], 0, bytes_to_pad);
105 *index += bytes_to_pad;
106 }
107 }
108 RTC_DCHECK_EQ(index_end, *index);
109 return true;
110 }
111
WithCsrc(uint32_t csrc)112 bool Bye::WithCsrc(uint32_t csrc) {
113 if (csrcs_.size() >= kMaxNumberOfCsrcs) {
114 LOG(LS_WARNING) << "Max CSRC size reached.";
115 return false;
116 }
117 csrcs_.push_back(csrc);
118 return true;
119 }
120
WithReason(const std::string & reason)121 void Bye::WithReason(const std::string& reason) {
122 RTC_DCHECK_LE(reason.size(), 0xffu);
123 reason_ = reason;
124 }
125
BlockLength() const126 size_t Bye::BlockLength() const {
127 size_t src_count = (1 + csrcs_.size());
128 size_t reason_size_in_32bits = reason_.empty() ? 0 : (reason_.size() / 4 + 1);
129 return kHeaderLength + 4 * (src_count + reason_size_in_32bits);
130 }
131
132 } // namespace rtcp
133 } // namespace webrtc
134