Fixing some issues with the direction attribute of m-lines in offers.

talk/session/media/mediasession.cc

 /*
  * libjingle
  * Copyright 2004 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 1018 matching lines @@
   // Make sure the answer media content direction is per default set as
   // described in RFC3264 section 6.1.
   switch (offer->direction()) {
     case MD_INACTIVE:
       answer->set_direction(MD_INACTIVE);
       break;
     case MD_SENDONLY:
       answer->set_direction(MD_RECVONLY);
       break;
     case MD_RECVONLY:
-      answer->set_direction(MD_SENDONLY);
+      answer->set_direction(answer->streams().empty() ? MD_INACTIVE
+                                                      : MD_SENDONLY);
       break;
     case MD_SENDRECV:
-      answer->set_direction(MD_SENDRECV);
+      answer->set_direction(answer->streams().empty() ? MD_RECVONLY
+                                                      : MD_SENDRECV);

[pthatcher, 2015/11/23 18:00:52]

It looks like this breaks data channels.  If we're answering data channels, we
should probably always go to sendrecv/sendonly.  

This was reported for C++ data channels (native/mobile apps), but we should see
if this affects Chrome as well.  If it is, we'll need to merge a fix ASAP. 

https://bugs.chromium.org/p/webrtc/issues/detail?id=5228#c5

       break;
     default:
+      RTC_DCHECK(false && "MediaContentDescription has unexpected direction.");
       break;
   }
 
   return true;
 }
 
 static bool IsMediaProtocolSupported(MediaType type,
                                      const std::string& protocol,
                                      bool secure_transport) {
   // Data channels can have a protocol of SCTP or SCTP/DTLS.
@@ skipping 467 matching lines @@
           add_legacy_,
           current_streams,
           audio.get())) {
     return false;
   }
   audio->set_lang(lang_);
 
   bool secure_transport = (transport_desc_factory_->secure() != SEC_DISABLED);
   SetMediaProtocol(secure_transport, audio.get());
 
-  if (!options.recv_audio) {
-    audio->set_direction(MD_SENDONLY);
+  if (!audio->streams().empty()) {
+    if (options.recv_audio) {
+      audio->set_direction(MD_SENDRECV);
+    } else {
+      audio->set_direction(MD_SENDONLY);
+    }
+  } else {
+    if (options.recv_audio) {
+      audio->set_direction(MD_RECVONLY);
+    } else {
+      audio->set_direction(MD_INACTIVE);
+    }
   }
 
   desc->AddContent(CN_AUDIO, NS_JINGLE_RTP, audio.release());
   if (!AddTransportOffer(CN_AUDIO, options.transport_options,
                          current_description, desc)) {
     return false;
   }
 
   return true;
 }
@@ skipping 23 matching lines @@
           current_streams,
           video.get())) {
     return false;
   }
 
   video->set_bandwidth(options.video_bandwidth);
 
   bool secure_transport = (transport_desc_factory_->secure() != SEC_DISABLED);
   SetMediaProtocol(secure_transport, video.get());
 
-  if (!options.recv_video) {
-    video->set_direction(MD_SENDONLY);
+  if (!video->streams().empty()) {
+    if (options.recv_video) {
+      video->set_direction(MD_SENDRECV);
+    } else {
+      video->set_direction(MD_SENDONLY);
+    }
+  } else {
+    if (options.recv_video) {
+      video->set_direction(MD_RECVONLY);
+    } else {
+      video->set_direction(MD_INACTIVE);
+    }
   }
 
   desc->AddContent(CN_VIDEO, NS_JINGLE_RTP, video.release());
   if (!AddTransportOffer(CN_VIDEO, options.transport_options,
                          current_description, desc)) {
     return false;
   }
 
   return true;
 }
@@ skipping 312 matching lines @@
       GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_VIDEO));
 }
 
 const DataContentDescription* GetFirstDataContentDescription(
     const SessionDescription* sdesc) {
   return static_cast<const DataContentDescription*>(
       GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_DATA));
 }
 
 }  // namespace cricket