Bumped version to 0.11.4

Update usrsctp and mitigate possible data race

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.7)
 project(libdatachannel
-	VERSION 0.11.3
+	VERSION 0.11.4
 	LANGUAGES CXX)
 set(PROJECT_DESCRIPTION "WebRTC Data Channels Library")
 

src/peerconnection.cpp

@@ -667,6 +667,8 @@ void PeerConnection::forwardMessage(message_ptr message) {
 			                                                  stream);
 			channel->onOpen(weak_bind(&PeerConnection::triggerDataChannel, this,
 			                          weak_ptr<DataChannel>{channel}));
+
+			std::unique_lock lock(mDataChannelsMutex); // we are going to emplace
 			mDataChannels.emplace(stream, channel);
 		} else {
 			// Invalid, close the DataChannel

src/sctptransport.cpp

@@ -349,6 +349,10 @@ void SctpTransport::incoming(message_ptr message) {
 	}
 
 	PLOG_VERBOSE << "Incoming size=" << message->size();
+
+	// TODO: There seems to be a possible data race between usrsctp_sendv() and usrsctp_conninput()
+	// As a mitigation, lock the send mutex before calling usrsctp_conninput()
+	std::lock_guard lock(mSendMutex);
 	usrsctp_conninput(this, message->data(), message->size(), 0);
 }