1/*
2 * libjingle
3 * Copyright 2011 Google Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 *  1. Redistributions of source code must retain the above copyright notice,
9 *     this list of conditions and the following disclaimer.
10 *  2. Redistributions in binary form must reproduce the above copyright notice,
11 *     this list of conditions and the following disclaimer in the documentation
12 *     and/or other materials provided with the distribution.
13 *  3. The name of the author may not be used to endorse or promote products
14 *     derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include "talk/media/base/rtputils.h"
29
30namespace cricket {
31
32static const int kRtpVersion = 2;
33static const size_t kRtpFlagsOffset = 0;
34static const size_t kRtpPayloadTypeOffset = 1;
35static const size_t kRtpSeqNumOffset = 2;
36static const size_t kRtpTimestampOffset = 4;
37static const size_t kRtpSsrcOffset = 8;
38static const size_t kRtcpPayloadTypeOffset = 1;
39
40bool GetUint8(const void* data, size_t offset, int* value) {
41  if (!data || !value) {
42    return false;
43  }
44  *value = *(static_cast<const uint8*>(data) + offset);
45  return true;
46}
47
48bool GetUint16(const void* data, size_t offset, int* value) {
49  if (!data || !value) {
50    return false;
51  }
52  *value = static_cast<int>(
53      rtc::GetBE16(static_cast<const uint8*>(data) + offset));
54  return true;
55}
56
57bool GetUint32(const void* data, size_t offset, uint32* value) {
58  if (!data || !value) {
59    return false;
60  }
61  *value = rtc::GetBE32(static_cast<const uint8*>(data) + offset);
62  return true;
63}
64
65bool SetUint8(void* data, size_t offset, int value) {
66  if (!data) {
67    return false;
68  }
69  rtc::Set8(data, offset, value);
70  return true;
71}
72
73bool SetUint16(void* data, size_t offset, int value) {
74  if (!data) {
75    return false;
76  }
77  rtc::SetBE16(static_cast<uint8*>(data) + offset, value);
78  return true;
79}
80
81bool SetUint32(void* data, size_t offset, uint32 value) {
82  if (!data) {
83    return false;
84  }
85  rtc::SetBE32(static_cast<uint8*>(data) + offset, value);
86  return true;
87}
88
89bool GetRtpFlags(const void* data, size_t len, int* value) {
90  if (len < kMinRtpPacketLen) {
91    return false;
92  }
93  return GetUint8(data, kRtpFlagsOffset, value);
94}
95
96bool GetRtpPayloadType(const void* data, size_t len, int* value) {
97  if (len < kMinRtpPacketLen) {
98    return false;
99  }
100  if (!GetUint8(data, kRtpPayloadTypeOffset, value)) {
101    return false;
102  }
103  *value &= 0x7F;
104  return true;
105}
106
107bool GetRtpSeqNum(const void* data, size_t len, int* value) {
108  if (len < kMinRtpPacketLen) {
109    return false;
110  }
111  return GetUint16(data, kRtpSeqNumOffset, value);
112}
113
114bool GetRtpTimestamp(const void* data, size_t len, uint32* value) {
115  if (len < kMinRtpPacketLen) {
116    return false;
117  }
118  return GetUint32(data, kRtpTimestampOffset, value);
119}
120
121bool GetRtpSsrc(const void* data, size_t len, uint32* value) {
122  if (len < kMinRtpPacketLen) {
123    return false;
124  }
125  return GetUint32(data, kRtpSsrcOffset, value);
126}
127
128bool GetRtpHeaderLen(const void* data, size_t len, size_t* value) {
129  if (!data || len < kMinRtpPacketLen || !value) return false;
130  const uint8* header = static_cast<const uint8*>(data);
131  // Get base header size + length of CSRCs (not counting extension yet).
132  size_t header_size = kMinRtpPacketLen + (header[0] & 0xF) * sizeof(uint32);
133  if (len < header_size) return false;
134  // If there's an extension, read and add in the extension size.
135  if (header[0] & 0x10) {
136    if (len < header_size + sizeof(uint32)) return false;
137    header_size += ((rtc::GetBE16(header + header_size + 2) + 1) *
138                    sizeof(uint32));
139    if (len < header_size) return false;
140  }
141  *value = header_size;
142  return true;
143}
144
145bool GetRtpVersion(const void* data, size_t len, int* version) {
146  if (len == 0) {
147    return false;
148  }
149
150  const uint8 first = static_cast<const uint8*>(data)[0];
151  *version = static_cast<int>((first >> 6) & 0x3);
152  return true;
153}
154
155bool GetRtpHeader(const void* data, size_t len, RtpHeader* header) {
156  return (GetRtpPayloadType(data, len, &(header->payload_type)) &&
157          GetRtpSeqNum(data, len, &(header->seq_num)) &&
158          GetRtpTimestamp(data, len, &(header->timestamp)) &&
159          GetRtpSsrc(data, len, &(header->ssrc)));
160}
161
162bool GetRtcpType(const void* data, size_t len, int* value) {
163  if (len < kMinRtcpPacketLen) {
164    return false;
165  }
166  return GetUint8(data, kRtcpPayloadTypeOffset, value);
167}
168
169// This method returns SSRC first of RTCP packet, except if packet is SDES.
170// TODO(mallinath) - Fully implement RFC 5506. This standard doesn't restrict
171// to send non-compound packets only to feedback messages.
172bool GetRtcpSsrc(const void* data, size_t len, uint32* value) {
173  // Packet should be at least of 8 bytes, to get SSRC from a RTCP packet.
174  if (!data || len < kMinRtcpPacketLen + 4 || !value) return false;
175  int pl_type;
176  if (!GetRtcpType(data, len, &pl_type)) return false;
177  // SDES packet parsing is not supported.
178  if (pl_type == kRtcpTypeSDES) return false;
179  *value = rtc::GetBE32(static_cast<const uint8*>(data) + 4);
180  return true;
181}
182
183bool SetRtpHeaderFlags(
184    void* data, size_t len,
185    bool padding, bool extension, int csrc_count) {
186  if (csrc_count > 0x0F) {
187    return false;
188  }
189  int flags = 0;
190  flags |= (kRtpVersion << 6);
191  flags |= ((padding ? 1 : 0) << 5);
192  flags |= ((extension ? 1 : 0) << 4);
193  flags |= csrc_count;
194  return SetUint8(data, kRtpFlagsOffset, flags);
195}
196
197// Assumes marker bit is 0.
198bool SetRtpPayloadType(void* data, size_t len, int value) {
199  if (value >= 0x7F) {
200    return false;
201  }
202  return SetUint8(data, kRtpPayloadTypeOffset, value & 0x7F);
203}
204
205bool SetRtpSeqNum(void* data, size_t len, int value) {
206  return SetUint16(data, kRtpSeqNumOffset, value);
207}
208
209bool SetRtpTimestamp(void* data, size_t len, uint32 value) {
210  return SetUint32(data, kRtpTimestampOffset, value);
211}
212
213bool SetRtpSsrc(void* data, size_t len, uint32 value) {
214  return SetUint32(data, kRtpSsrcOffset, value);
215}
216
217// Assumes version 2, no padding, no extensions, no csrcs.
218bool SetRtpHeader(void* data, size_t len, const RtpHeader& header) {
219  return (SetRtpHeaderFlags(data, len, false, false, 0) &&
220          SetRtpPayloadType(data, len, header.payload_type) &&
221          SetRtpSeqNum(data, len, header.seq_num) &&
222          SetRtpTimestamp(data, len, header.timestamp) &&
223          SetRtpSsrc(data, len, header.ssrc));
224}
225
226bool IsRtpPacket(const void* data, size_t len) {
227  if (len < kMinRtpPacketLen)
228    return false;
229
230  int version = 0;
231  if (!GetRtpVersion(data, len, &version))
232    return false;
233
234  return version == kRtpVersion;
235}
236
237}  // namespace cricket
238