1/*
2 * libjingle
3 * Copyright 2004 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/session/media/rtcpmuxfilter.h"
29
30#include "webrtc/base/logging.h"
31
32namespace cricket {
33
34RtcpMuxFilter::RtcpMuxFilter() : state_(ST_INIT), offer_enable_(false) {
35}
36
37bool RtcpMuxFilter::IsActive() const {
38  return state_ == ST_SENTPRANSWER ||
39         state_ == ST_RECEIVEDPRANSWER ||
40         state_ == ST_ACTIVE;
41}
42
43bool RtcpMuxFilter::SetOffer(bool offer_enable, ContentSource src) {
44  if (!ExpectOffer(offer_enable, src)) {
45    LOG(LS_ERROR) << "Invalid state for change of RTCP mux offer";
46    return false;
47  }
48
49  offer_enable_ = offer_enable;
50  state_ = (src == CS_LOCAL) ? ST_SENTOFFER : ST_RECEIVEDOFFER;
51  return true;
52}
53
54bool RtcpMuxFilter::SetProvisionalAnswer(bool answer_enable,
55                                         ContentSource src) {
56  if (!ExpectAnswer(src)) {
57    LOG(LS_ERROR) << "Invalid state for RTCP mux provisional answer";
58    return false;
59  }
60
61  if (offer_enable_) {
62    if (answer_enable) {
63      if (src == CS_REMOTE)
64        state_ = ST_RECEIVEDPRANSWER;
65      else  // CS_LOCAL
66        state_ = ST_SENTPRANSWER;
67    } else {
68      // The provisional answer doesn't want to use RTCP mux.
69      // Go back to the original state after the offer was set and wait for next
70      // provisional or final answer.
71      if (src == CS_REMOTE)
72        state_ = ST_SENTOFFER;
73      else  // CS_LOCAL
74        state_ = ST_RECEIVEDOFFER;
75    }
76  } else if (answer_enable) {
77    // If the offer didn't specify RTCP mux, the answer shouldn't either.
78    LOG(LS_WARNING) << "Invalid parameters in RTCP mux provisional answer";
79    return false;
80  }
81
82  return true;
83}
84
85bool RtcpMuxFilter::SetAnswer(bool answer_enable, ContentSource src) {
86  if (!ExpectAnswer(src)) {
87    LOG(LS_ERROR) << "Invalid state for RTCP mux answer";
88    return false;
89  }
90
91  if (offer_enable_ && answer_enable) {
92    state_ = ST_ACTIVE;
93  } else if (answer_enable) {
94    // If the offer didn't specify RTCP mux, the answer shouldn't either.
95    LOG(LS_WARNING) << "Invalid parameters in RTCP mux answer";
96    return false;
97  } else {
98    state_ = ST_INIT;
99  }
100  return true;
101}
102
103bool RtcpMuxFilter::DemuxRtcp(const char* data, int len) {
104  // If we're muxing RTP/RTCP, we must inspect each packet delivered and
105  // determine whether it is RTP or RTCP. We do so by checking the packet type,
106  // and assuming RTP if type is 0-63 or 96-127. For additional details, see
107  // http://tools.ietf.org/html/rfc5761.
108  // Note that if we offer RTCP mux, we may receive muxed RTCP before we
109  // receive the answer, so we operate in that state too.
110  if (!offer_enable_ || state_ < ST_SENTOFFER) {
111    return false;
112  }
113
114  int type = (len >= 2) ? (static_cast<uint8>(data[1]) & 0x7F) : 0;
115  return (type >= 64 && type < 96);
116}
117
118bool RtcpMuxFilter::ExpectOffer(bool offer_enable, ContentSource source) {
119  return ((state_ == ST_INIT) ||
120          (state_ == ST_ACTIVE && offer_enable == offer_enable_) ||
121          (state_ == ST_SENTOFFER && source == CS_LOCAL) ||
122          (state_ == ST_RECEIVEDOFFER && source == CS_REMOTE));
123}
124
125bool RtcpMuxFilter::ExpectAnswer(ContentSource source) {
126  return ((state_ == ST_SENTOFFER && source == CS_REMOTE) ||
127          (state_ == ST_RECEIVEDOFFER && source == CS_LOCAL) ||
128          (state_ == ST_SENTPRANSWER && source == CS_LOCAL) ||
129          (state_ == ST_RECEIVEDPRANSWER && source == CS_REMOTE));
130}
131
132}  // namespace cricket
133