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 "modules/rtp_rtcp/source/rtcp_packet/bye.h"
12
13 #include <string.h>
14
15 #include <cstdint>
16 #include <utility>
17
18 #include "absl/strings/string_view.h"
19 #include "modules/rtp_rtcp/source/byte_io.h"
20 #include "modules/rtp_rtcp/source/rtcp_packet/common_header.h"
21 #include "rtc_base/checks.h"
22 #include "rtc_base/logging.h"
23
24 namespace webrtc {
25 namespace rtcp {
26 constexpr uint8_t Bye::kPacketType;
27 // Bye packet (BYE) (RFC 3550).
28 //
29 // 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
30 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
31 // |V=2|P| SC | PT=BYE=203 | length |
32 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
33 // | SSRC/CSRC |
34 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
35 // : ... :
36 // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
37 // (opt) | length | reason for leaving ...
38 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
39 Bye::Bye() = default;
40
41 Bye::~Bye() = default;
42
Parse(const CommonHeader & packet)43 bool Bye::Parse(const CommonHeader& packet) {
44 RTC_DCHECK_EQ(packet.type(), kPacketType);
45
46 const uint8_t src_count = packet.count();
47 // Validate packet.
48 if (packet.payload_size_bytes() < 4u * src_count) {
49 RTC_LOG(LS_WARNING)
50 << "Packet is too small to contain CSRCs it promise to have.";
51 return false;
52 }
53 const uint8_t* const payload = packet.payload();
54 bool has_reason = packet.payload_size_bytes() > 4u * src_count;
55 uint8_t reason_length = 0;
56 if (has_reason) {
57 reason_length = payload[4u * src_count];
58 if (packet.payload_size_bytes() - 4u * src_count < 1u + reason_length) {
59 RTC_LOG(LS_WARNING) << "Invalid reason length: " << reason_length;
60 return false;
61 }
62 }
63 // Once sure packet is valid, copy values.
64 if (src_count == 0) { // A count value of zero is valid, but useless.
65 SetSenderSsrc(0);
66 csrcs_.clear();
67 } else {
68 SetSenderSsrc(ByteReader<uint32_t>::ReadBigEndian(payload));
69 csrcs_.resize(src_count - 1);
70 for (size_t i = 1; i < src_count; ++i)
71 csrcs_[i - 1] = ByteReader<uint32_t>::ReadBigEndian(&payload[4 * i]);
72 }
73
74 if (has_reason) {
75 reason_.assign(reinterpret_cast<const char*>(&payload[4u * src_count + 1]),
76 reason_length);
77 } else {
78 reason_.clear();
79 }
80
81 return true;
82 }
83
Create(uint8_t * packet,size_t * index,size_t max_length,PacketReadyCallback callback) const84 bool Bye::Create(uint8_t* packet,
85 size_t* index,
86 size_t max_length,
87 PacketReadyCallback callback) const {
88 while (*index + BlockLength() > max_length) {
89 if (!OnBufferFull(packet, index, callback))
90 return false;
91 }
92 const size_t index_end = *index + BlockLength();
93
94 CreateHeader(1 + csrcs_.size(), kPacketType, HeaderLength(), packet, index);
95 // Store srcs of the leaving clients.
96 ByteWriter<uint32_t>::WriteBigEndian(&packet[*index], sender_ssrc());
97 *index += sizeof(uint32_t);
98 for (uint32_t csrc : csrcs_) {
99 ByteWriter<uint32_t>::WriteBigEndian(&packet[*index], csrc);
100 *index += sizeof(uint32_t);
101 }
102 // Store the reason to leave.
103 if (!reason_.empty()) {
104 uint8_t reason_length = static_cast<uint8_t>(reason_.size());
105 packet[(*index)++] = reason_length;
106 memcpy(&packet[*index], reason_.data(), reason_length);
107 *index += reason_length;
108 // Add padding bytes if needed.
109 size_t bytes_to_pad = index_end - *index;
110 RTC_DCHECK_LE(bytes_to_pad, 3);
111 if (bytes_to_pad > 0) {
112 memset(&packet[*index], 0, bytes_to_pad);
113 *index += bytes_to_pad;
114 }
115 }
116 RTC_DCHECK_EQ(index_end, *index);
117 return true;
118 }
119
SetCsrcs(std::vector<uint32_t> csrcs)120 bool Bye::SetCsrcs(std::vector<uint32_t> csrcs) {
121 if (csrcs.size() > kMaxNumberOfCsrcs) {
122 RTC_LOG(LS_WARNING) << "Too many CSRCs for Bye packet.";
123 return false;
124 }
125 csrcs_ = std::move(csrcs);
126 return true;
127 }
128
SetReason(absl::string_view reason)129 void Bye::SetReason(absl::string_view reason) {
130 RTC_DCHECK_LE(reason.size(), 0xffu);
131 reason_ = std::string(reason);
132 }
133
BlockLength() const134 size_t Bye::BlockLength() const {
135 size_t src_count = (1 + csrcs_.size());
136 size_t reason_size_in_32bits = reason_.empty() ? 0 : (reason_.size() / 4 + 1);
137 return kHeaderLength + 4 * (src_count + reason_size_in_32bits);
138 }
139
140 } // namespace rtcp
141 } // namespace webrtc
142