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/common_header.h"
12 
13 #include "webrtc/base/logging.h"
14 #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
15 
16 namespace webrtc {
17 namespace rtcp {
18 //    0                   1           1       2                   3
19 //    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
20 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
21 // 0 |V=2|P|   C/F   |
22 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
23 // 1                 |  Packet Type  |
24 //   ----------------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
25 // 2                                 |             length            |
26 //   --------------------------------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
27 //
28 // Common header for all RTCP packets, 4 octets.
Parse(const uint8_t * buffer,size_t size_bytes)29 bool CommonHeader::Parse(const uint8_t* buffer, size_t size_bytes) {
30   const size_t kHeaderSizeBytes = 4;
31   const uint8_t kVersion = 2;
32 
33   if (size_bytes < kHeaderSizeBytes) {
34     LOG(LS_WARNING) << "Too little data (" << size_bytes << " byte"
35                     << (size_bytes != 1 ? "s" : "")
36                     << ") remaining in buffer to parse RTCP header (4 bytes).";
37     return false;
38   }
39 
40   uint8_t version = buffer[0] >> 6;
41   if (version != kVersion) {
42     LOG(LS_WARNING) << "Invalid RTCP header: Version must be "
43                     << static_cast<int>(kVersion) << " but was "
44                     << static_cast<int>(version);
45     return false;
46   }
47 
48   bool has_padding = (buffer[0] & 0x20) != 0;
49   count_or_format_ = buffer[0] & 0x1F;
50   packet_type_ = buffer[1];
51   payload_size_ = ByteReader<uint16_t>::ReadBigEndian(&buffer[2]) * 4;
52   payload_ = buffer + kHeaderSizeBytes;
53   padding_size_ = 0;
54 
55   if (size_bytes < kHeaderSizeBytes + payload_size_) {
56     LOG(LS_WARNING) << "Buffer too small (" << size_bytes
57                     << " bytes) to fit an RtcpPacket with a header and "
58                     << payload_size_ << " bytes.";
59     return false;
60   }
61 
62   if (has_padding) {
63     if (payload_size_ == 0) {
64       LOG(LS_WARNING) << "Invalid RTCP header: Padding bit set but 0 payload "
65                          "size specified.";
66       return false;
67     }
68 
69     padding_size_ = payload_[payload_size_ - 1];
70     if (padding_size_ == 0) {
71       LOG(LS_WARNING) << "Invalid RTCP header: Padding bit set but 0 padding "
72                          "size specified.";
73       return false;
74     }
75     if (padding_size_ > payload_size_) {
76       LOG(LS_WARNING) << "Invalid RTCP header: Too many padding bytes ("
77                       << padding_size_ << ") for a packet payload size of "
78                       << payload_size_ << " bytes.";
79       return false;
80     }
81     payload_size_ -= padding_size_;
82   }
83   return true;
84 }
85 }  // namespace rtcp
86 }  // namespace webrtc
87