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/sdes.h"
12 :
13 : #include <utility>
14 :
15 : #include "webrtc/base/checks.h"
16 : #include "webrtc/base/logging.h"
17 : #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
18 : #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/common_header.h"
19 :
20 : namespace webrtc {
21 : namespace rtcp {
22 : constexpr uint8_t Sdes::kPacketType;
23 : // Source Description (SDES) (RFC 3550).
24 : //
25 : // 0 1 2 3
26 : // 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
27 : // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
28 : // header |V=2|P| SC | PT=SDES=202 | length |
29 : // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
30 : // chunk | SSRC/CSRC_1 |
31 : // 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
32 : // | SDES items |
33 : // | ... |
34 : // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
35 : // chunk | SSRC/CSRC_2 |
36 : // 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
37 : // | SDES items |
38 : // | ... |
39 : // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
40 : //
41 : // Canonical End-Point Identifier SDES Item (CNAME)
42 : //
43 : // 0 1 2 3
44 : // 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
45 : // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
46 : // | CNAME=1 | length | user and domain name ...
47 : // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
48 : namespace {
49 : const uint8_t kTerminatorTag = 0;
50 : const uint8_t kCnameTag = 1;
51 :
52 0 : size_t ChunkSize(const Sdes::Chunk& chunk) {
53 : // Chunk:
54 : // SSRC/CSRC (4 bytes) | CNAME=1 (1 byte) | length (1 byte) | cname | padding.
55 0 : size_t chunk_payload_size = 4 + 1 + 1 + chunk.cname.size();
56 0 : size_t padding_size = 4 - (chunk_payload_size % 4); // Minimum 1.
57 0 : return chunk_payload_size + padding_size;
58 : }
59 : } // namespace
60 :
61 0 : Sdes::Sdes() : block_length_(RtcpPacket::kHeaderLength) {}
62 :
63 0 : Sdes::~Sdes() {}
64 :
65 0 : bool Sdes::Parse(const CommonHeader& packet) {
66 0 : RTC_DCHECK_EQ(packet.type(), kPacketType);
67 :
68 0 : uint8_t number_of_chunks = packet.count();
69 0 : std::vector<Chunk> chunks; // Read chunk into temporary array, so that in
70 : // case of an error original array would stay
71 : // unchanged.
72 0 : size_t block_length = kHeaderLength;
73 :
74 0 : if (packet.payload_size_bytes() % 4 != 0) {
75 0 : LOG(LS_WARNING) << "Invalid payload size " << packet.payload_size_bytes()
76 : << " bytes for a valid Sdes packet. Size should be"
77 0 : " multiple of 4 bytes";
78 : }
79 : const uint8_t* const payload_end =
80 0 : packet.payload() + packet.payload_size_bytes();
81 0 : const uint8_t* looking_at = packet.payload();
82 0 : chunks.resize(number_of_chunks);
83 0 : for (size_t i = 0; i < number_of_chunks;) {
84 : // Each chunk consumes at least 8 bytes.
85 0 : if (payload_end - looking_at < 8) {
86 0 : LOG(LS_WARNING) << "Not enough space left for chunk #" << (i + 1);
87 0 : return false;
88 : }
89 0 : chunks[i].ssrc = ByteReader<uint32_t>::ReadBigEndian(looking_at);
90 0 : looking_at += sizeof(uint32_t);
91 0 : bool cname_found = false;
92 :
93 : uint8_t item_type;
94 0 : while ((item_type = *(looking_at++)) != kTerminatorTag) {
95 0 : if (looking_at >= payload_end) {
96 0 : LOG(LS_WARNING) << "Unexpected end of packet while reading chunk #"
97 0 : << (i + 1) << ". Expected to find size of the text.";
98 0 : return false;
99 : }
100 0 : uint8_t item_length = *(looking_at++);
101 0 : const size_t kTerminatorSize = 1;
102 0 : if (looking_at + item_length + kTerminatorSize > payload_end) {
103 0 : LOG(LS_WARNING) << "Unexpected end of packet while reading chunk #"
104 0 : << (i + 1) << ". Expected to find text of size "
105 0 : << item_length;
106 0 : return false;
107 : }
108 0 : if (item_type == kCnameTag) {
109 0 : if (cname_found) {
110 0 : LOG(LS_WARNING) << "Found extra CNAME for same ssrc in chunk #"
111 0 : << (i + 1);
112 0 : return false;
113 : }
114 0 : cname_found = true;
115 0 : chunks[i].cname.assign(reinterpret_cast<const char*>(looking_at),
116 0 : item_length);
117 : }
118 0 : looking_at += item_length;
119 : }
120 0 : if (cname_found) {
121 : // block_length calculates length of the packet that would be generated by
122 : // Build/Create functions. Adjust it same way WithCName function does.
123 0 : block_length += ChunkSize(chunks[i]);
124 0 : ++i;
125 : } else {
126 : // RFC states CNAME item is mandatory.
127 : // But same time it allows chunk without items.
128 : // So while parsing, ignore all chunks without cname,
129 : // but do not fail the parse.
130 0 : LOG(LS_WARNING) << "CNAME not found for ssrc " << chunks[i].ssrc;
131 0 : --number_of_chunks;
132 0 : chunks.resize(number_of_chunks);
133 : }
134 : // Adjust to 32bit boundary.
135 0 : looking_at += (payload_end - looking_at) % 4;
136 : }
137 :
138 0 : chunks_ = std::move(chunks);
139 0 : block_length_ = block_length;
140 0 : return true;
141 : }
142 :
143 0 : bool Sdes::AddCName(uint32_t ssrc, std::string cname) {
144 0 : RTC_DCHECK_LE(cname.length(), 0xffu);
145 0 : if (chunks_.size() >= kMaxNumberOfChunks) {
146 0 : LOG(LS_WARNING) << "Max SDES chunks reached.";
147 0 : return false;
148 : }
149 0 : Chunk chunk;
150 0 : chunk.ssrc = ssrc;
151 0 : chunk.cname = std::move(cname);
152 0 : chunks_.push_back(chunk);
153 0 : block_length_ += ChunkSize(chunk);
154 0 : return true;
155 : }
156 :
157 0 : bool Sdes::Create(uint8_t* packet,
158 : size_t* index,
159 : size_t max_length,
160 : RtcpPacket::PacketReadyCallback* callback) const {
161 0 : while (*index + BlockLength() > max_length) {
162 0 : if (!OnBufferFull(packet, index, callback))
163 0 : return false;
164 : }
165 0 : const size_t index_end = *index + BlockLength();
166 0 : CreateHeader(chunks_.size(), kPacketType, HeaderLength(), packet, index);
167 :
168 0 : for (const Sdes::Chunk& chunk : chunks_) {
169 0 : ByteWriter<uint32_t>::WriteBigEndian(&packet[*index + 0], chunk.ssrc);
170 0 : ByteWriter<uint8_t>::WriteBigEndian(&packet[*index + 4], kCnameTag);
171 0 : ByteWriter<uint8_t>::WriteBigEndian(&packet[*index + 5],
172 0 : chunk.cname.size());
173 0 : memcpy(&packet[*index + 6], chunk.cname.data(), chunk.cname.size());
174 0 : *index += (6 + chunk.cname.size());
175 :
176 : // In each chunk, the list of items must be terminated by one or more null
177 : // octets. The next chunk must start on a 32-bit boundary.
178 : // CNAME (1 byte) | length (1 byte) | name | padding.
179 0 : size_t padding_size = 4 - ((6 + chunk.cname.size()) % 4);
180 0 : const int kPadding = 0;
181 0 : memset(packet + *index, kPadding, padding_size);
182 0 : *index += padding_size;
183 : }
184 :
185 0 : RTC_CHECK_EQ(*index, index_end);
186 0 : return true;
187 : }
188 : } // namespace rtcp
189 : } // namespace webrtc
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