1 // Copyright 2013 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "media/cast/transport/rtcp/rtcp_builder.h"
11 #include "base/big_endian.h"
12 #include "base/logging.h"
13 #include "media/cast/transport/cast_transport_defines.h"
14 #include "media/cast/transport/pacing/paced_sender.h"
16 static const size_t kRtcpCastLogHeaderSize = 12;
17 static const size_t kRtcpSenderFrameLogSize = 4;
24 // RFC 3550 page 44, including end null.
25 static const uint32 kCast = ('C' << 24) + ('A' << 16) + ('S' << 8) + 'T';
26 static const uint8 kSenderLogSubtype = 1;
29 RtcpBuilder::RtcpBuilder(PacedSender* const outgoing_transport)
30 : transport_(outgoing_transport),
34 RtcpBuilder::~RtcpBuilder() {}
36 void RtcpBuilder::SendRtcpFromRtpSender(
37 uint32 packet_type_flags,
38 const RtcpSenderInfo& sender_info,
39 const RtcpDlrrReportBlock& dlrr,
40 const RtcpSenderLogMessage& sender_log,
42 const std::string& c_name) {
43 if (packet_type_flags & kRtcpRr ||
44 packet_type_flags & kRtcpPli ||
45 packet_type_flags & kRtcpRrtr ||
46 packet_type_flags & kRtcpCast ||
47 packet_type_flags & kRtcpReceiverLog ||
48 packet_type_flags & kRtcpRpsi ||
49 packet_type_flags & kRtcpRemb ||
50 packet_type_flags & kRtcpNack) {
51 NOTREACHED() << "Invalid argument";
55 PacketRef packet(new base::RefCountedData<Packet>);
56 packet->data.reserve(kMaxIpPacketSize);
57 if (packet_type_flags & kRtcpSr) {
58 if (!BuildSR(sender_info, &packet->data)) return;
59 if (!BuildSdec(&packet->data)) return;
61 if (packet_type_flags & kRtcpBye) {
62 if (!BuildBye(&packet->data)) return;
64 if (packet_type_flags & kRtcpDlrr) {
65 if (!BuildDlrrRb(dlrr, &packet->data)) return;
67 if (packet_type_flags & kRtcpSenderLog) {
68 if (!BuildSenderLog(sender_log, &packet->data)) return;
70 if (packet->data.empty())
71 return; // Sanity - don't send empty packets.
73 transport_->SendRtcpPacket(ssrc_, packet);
76 bool RtcpBuilder::BuildSR(const RtcpSenderInfo& sender_info,
77 Packet* packet) const {
79 size_t start_size = packet->size();
80 if (start_size + 52 > kMaxIpPacketSize) {
81 DLOG(FATAL) << "Not enough buffer space";
85 uint16 number_of_rows = 6;
86 packet->resize(start_size + 28);
88 base::BigEndianWriter big_endian_writer(
89 reinterpret_cast<char*>(&((*packet)[start_size])), 28);
90 big_endian_writer.WriteU8(0x80);
91 big_endian_writer.WriteU8(kPacketTypeSenderReport);
92 big_endian_writer.WriteU16(number_of_rows);
93 big_endian_writer.WriteU32(ssrc_);
94 big_endian_writer.WriteU32(sender_info.ntp_seconds);
95 big_endian_writer.WriteU32(sender_info.ntp_fraction);
96 big_endian_writer.WriteU32(sender_info.rtp_timestamp);
97 big_endian_writer.WriteU32(sender_info.send_packet_count);
98 big_endian_writer.WriteU32(static_cast<uint32>(sender_info.send_octet_count));
102 bool RtcpBuilder::BuildSdec(Packet* packet) const {
103 size_t start_size = packet->size();
104 if (start_size + 12 + c_name_.length() > kMaxIpPacketSize) {
105 DLOG(FATAL) << "Not enough buffer space";
109 // SDES Source Description.
110 packet->resize(start_size + 10);
112 base::BigEndianWriter big_endian_writer(
113 reinterpret_cast<char*>(&((*packet)[start_size])), 10);
114 // We always need to add one SDES CNAME.
115 big_endian_writer.WriteU8(0x80 + 1);
116 big_endian_writer.WriteU8(kPacketTypeSdes);
118 // Handle SDES length later on.
119 uint32 sdes_length_position = static_cast<uint32>(start_size) + 3;
120 big_endian_writer.WriteU16(0);
121 big_endian_writer.WriteU32(ssrc_); // Add our own SSRC.
122 big_endian_writer.WriteU8(1); // CNAME = 1
123 big_endian_writer.WriteU8(static_cast<uint8>(c_name_.length()));
125 size_t sdes_length = 10 + c_name_.length();
126 packet->insert(packet->end(), c_name_.c_str(),
127 c_name_.c_str() + c_name_.length());
131 // We must have a zero field even if we have an even multiple of 4 bytes.
132 if ((packet->size() % 4) == 0) {
134 packet->push_back(0);
136 while ((packet->size() % 4) != 0) {
138 packet->push_back(0);
140 sdes_length += padding;
142 // In 32-bit words minus one and we don't count the header.
143 uint8 buffer_length = static_cast<uint8>((sdes_length / 4) - 1);
144 (*packet)[sdes_length_position] = buffer_length;
148 bool RtcpBuilder::BuildBye(Packet* packet) const {
149 size_t start_size = packet->size();
150 if (start_size + 8 > kMaxIpPacketSize) {
151 DLOG(FATAL) << "Not enough buffer space";
155 packet->resize(start_size + 8);
157 base::BigEndianWriter big_endian_writer(
158 reinterpret_cast<char*>(&((*packet)[start_size])), 8);
159 big_endian_writer.WriteU8(0x80 + 1);
160 big_endian_writer.WriteU8(kPacketTypeBye);
161 big_endian_writer.WriteU16(1); // Length.
162 big_endian_writer.WriteU32(ssrc_); // Add our own SSRC.
168 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
169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
170 |V=2|P|reserved | PT=XR=207 | length |
171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
174 | BT=5 | reserved | block length |
175 +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
176 | SSRC_1 (SSRC of first receiver) | sub-
177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ block
179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
180 | delay since last RR (DLRR) |
181 +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
183 bool RtcpBuilder::BuildDlrrRb(const RtcpDlrrReportBlock& dlrr,
184 Packet* packet) const {
185 size_t start_size = packet->size();
186 if (start_size + 24 > kMaxIpPacketSize) {
187 DLOG(FATAL) << "Not enough buffer space";
191 packet->resize(start_size + 24);
193 base::BigEndianWriter big_endian_writer(
194 reinterpret_cast<char*>(&((*packet)[start_size])), 24);
195 big_endian_writer.WriteU8(0x80);
196 big_endian_writer.WriteU8(kPacketTypeXr);
197 big_endian_writer.WriteU16(5); // Length.
198 big_endian_writer.WriteU32(ssrc_); // Add our own SSRC.
199 big_endian_writer.WriteU8(5); // Add block type.
200 big_endian_writer.WriteU8(0); // Add reserved.
201 big_endian_writer.WriteU16(3); // Block length.
202 big_endian_writer.WriteU32(ssrc_); // Add the media (received RTP) SSRC.
203 big_endian_writer.WriteU32(dlrr.last_rr);
204 big_endian_writer.WriteU32(dlrr.delay_since_last_rr);
208 bool RtcpBuilder::BuildSenderLog(const RtcpSenderLogMessage& sender_log_message,
209 Packet* packet) const {
211 size_t start_size = packet->size();
212 size_t remaining_space = kMaxIpPacketSize - start_size;
213 if (remaining_space < kRtcpCastLogHeaderSize + kRtcpSenderFrameLogSize) {
214 DLOG(FATAL) << "Not enough buffer space";
218 size_t space_for_x_messages =
219 (remaining_space - kRtcpCastLogHeaderSize) / kRtcpSenderFrameLogSize;
220 size_t number_of_messages = std::min(space_for_x_messages,
221 sender_log_message.size());
223 size_t log_size = kRtcpCastLogHeaderSize +
224 number_of_messages * kRtcpSenderFrameLogSize;
225 packet->resize(start_size + log_size);
227 base::BigEndianWriter big_endian_writer(
228 reinterpret_cast<char*>(&((*packet)[start_size])), log_size);
229 big_endian_writer.WriteU8(0x80 + kSenderLogSubtype);
230 big_endian_writer.WriteU8(kPacketTypeApplicationDefined);
231 big_endian_writer.WriteU16(static_cast<uint16>(2 + number_of_messages));
232 big_endian_writer.WriteU32(ssrc_); // Add our own SSRC.
233 big_endian_writer.WriteU32(kCast);
235 std::vector<RtcpSenderFrameLogMessage>::const_iterator it =
236 sender_log_message.begin();
237 for (; number_of_messages > 0; --number_of_messages) {
238 DCHECK(!sender_log_message.empty());
239 const RtcpSenderFrameLogMessage& message = *it;
240 big_endian_writer.WriteU8(static_cast<uint8>(message.frame_status));
241 // We send the 24 east significant bits of the RTP timestamp.
242 big_endian_writer.WriteU8(static_cast<uint8>(message.rtp_timestamp >> 16));
243 big_endian_writer.WriteU8(static_cast<uint8>(message.rtp_timestamp >> 8));
244 big_endian_writer.WriteU8(static_cast<uint8>(message.rtp_timestamp));
250 } // namespace transport