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/dlrr.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 namespace webrtc {
18 namespace rtcp {
19 // DLRR Report Block (RFC 3611).
20 //
21 // 0 1 2 3
22 // 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
23 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
24 // | BT=5 | reserved | block length |
25 // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
26 // | SSRC_1 (SSRC of first receiver) | sub-
27 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ block
28 // | last RR (LRR) | 1
29 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
30 // | delay since last RR (DLRR) |
31 // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
32 // | SSRC_2 (SSRC of second receiver) | sub-
33 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ block
34 // : ... : 2
Parse(const uint8_t * buffer,uint16_t block_length_32bits)35 bool Dlrr::Parse(const uint8_t* buffer, uint16_t block_length_32bits) {
36 RTC_DCHECK(buffer[0] == kBlockType);
37 // kReserved = buffer[1];
38 RTC_DCHECK_EQ(block_length_32bits,
39 ByteReader<uint16_t>::ReadBigEndian(&buffer[2]));
40 if (block_length_32bits % 3 != 0) {
41 LOG(LS_WARNING) << "Invalid size for dlrr block.";
42 return false;
43 }
44
45 size_t blocks_count = block_length_32bits / 3;
46 const uint8_t* read_at = buffer + kBlockHeaderLength;
47 sub_blocks_.resize(blocks_count);
48 for (SubBlock& sub_block : sub_blocks_) {
49 sub_block.ssrc = ByteReader<uint32_t>::ReadBigEndian(&read_at[0]);
50 sub_block.last_rr = ByteReader<uint32_t>::ReadBigEndian(&read_at[4]);
51 sub_block.delay_since_last_rr =
52 ByteReader<uint32_t>::ReadBigEndian(&read_at[8]);
53 read_at += kSubBlockLength;
54 }
55 return true;
56 }
57
BlockLength() const58 size_t Dlrr::BlockLength() const {
59 if (sub_blocks_.empty())
60 return 0;
61 return kBlockHeaderLength + kSubBlockLength * sub_blocks_.size();
62 }
63
Create(uint8_t * buffer) const64 void Dlrr::Create(uint8_t* buffer) const {
65 if (sub_blocks_.empty()) // No subblocks, no need to write header either.
66 return;
67 // Create block header.
68 const uint8_t kReserved = 0;
69 buffer[0] = kBlockType;
70 buffer[1] = kReserved;
71 ByteWriter<uint16_t>::WriteBigEndian(&buffer[2], 3 * sub_blocks_.size());
72 // Create sub blocks.
73 uint8_t* write_at = buffer + kBlockHeaderLength;
74 for (const SubBlock& sub_block : sub_blocks_) {
75 ByteWriter<uint32_t>::WriteBigEndian(&write_at[0], sub_block.ssrc);
76 ByteWriter<uint32_t>::WriteBigEndian(&write_at[4], sub_block.last_rr);
77 ByteWriter<uint32_t>::WriteBigEndian(&write_at[8],
78 sub_block.delay_since_last_rr);
79 write_at += kSubBlockLength;
80 }
81 RTC_DCHECK_EQ(buffer + BlockLength(), write_at);
82 }
83
WithDlrrItem(uint32_t ssrc,uint32_t last_rr,uint32_t delay_last_rr)84 bool Dlrr::WithDlrrItem(uint32_t ssrc,
85 uint32_t last_rr,
86 uint32_t delay_last_rr) {
87 if (sub_blocks_.size() >= kMaxNumberOfDlrrItems) {
88 LOG(LS_WARNING) << "Max DLRR items reached.";
89 return false;
90 }
91 SubBlock block;
92 block.ssrc = ssrc;
93 block.last_rr = last_rr;
94 block.delay_since_last_rr = delay_last_rr;
95 sub_blocks_.push_back(block);
96 return true;
97 }
98
99 } // namespace rtcp
100 } // namespace webrtc
101