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      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 
     32 namespace cricket {
     33 
     34 RtcpMuxFilter::RtcpMuxFilter() : state_(ST_INIT), offer_enable_(false) {
     35 }
     36 
     37 bool RtcpMuxFilter::IsActive() const {
     38   return state_ == ST_SENTPRANSWER ||
     39          state_ == ST_RECEIVEDPRANSWER ||
     40          state_ == ST_ACTIVE;
     41 }
     42 
     43 bool 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 
     54 bool 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 
     85 bool 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 
    103 bool 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 
    118 bool 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 
    125 bool 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