Fix interoperability issue with Zfone3. Set the SSRC at the earliest possible time, start

ZRTP handshake only after SSRC is known to ZRTP. This modification disables half-duplex
(receive-only) RTP streams. This restriction may be lifted if "newmedia" goes into operation.

src/net/java/sip/communicator/impl/media/CallSessionImpl.java

@@ -1427,8 +1427,21 @@ else if (format instanceof AudioFormat)
 
             try
             {
-                rtpManager.createSendStream(dataSource, i);
+                SendStream sendStream = rtpManager.createSendStream(dataSource, i);
+                
+                TransformConnector transConnector =
+                    this.transConnectors.get(rtpManager);
 
+                // If a ZRTP engine is availabe then set the SSRC of this stream
+                // currently ZRTP supports only one SSRC per engine
+                if (transConnector != null)
+                {
+                    long ssrc = sendStream.getSSRC();
+
+                    ZRTPTransformEngine engine
+                        = (ZRTPTransformEngine) transConnector.getEngine();
+                    engine.setOwnSSRC(ssrc);
+                }
                 logger.trace("Created a send stream for format " + format);
             }
             catch (Exception exc)

src/net/java/sip/communicator/impl/media/transform/zrtp/ZRTPTransformEngine.java

@@ -480,6 +480,18 @@ public void cleanup()
         }
     }
 
+    /**
+     * Set the SSRC of the RTP transmitter stream.
+     * 
+     * ZRTP fills the SSRC in the ZRTP messages.
+     * 
+     * @param ssrc
+     */
+    public void setOwnSSRC(long ssrc) {
+        ownSSRC = (int)(ssrc & 0xffffffff);
+        System.out.println("Own SSRC: " + ownSSRC);
+    }
+
     /**
      * The data output stream calls this method to transform outgoing
      * packets.
@@ -527,7 +539,7 @@ public RawPacket reverseTransform(RawPacket pkt)
     {
 
         // Check if we need to start ZRTP
-        if (!started && enableZrtp)
+        if (!started && enableZrtp && ownSSRC != 0)
         {
             startZrtp();
         }
@@ -566,7 +578,7 @@ public RawPacket reverseTransform(RawPacket pkt)
          * In any case return null because ZRTP packets must never reach 
          * the application.
          */
-        if (enableZrtp)
+        if (enableZrtp && ownSSRC != 0)
         {
             ZrtpRawPacket zPkt = new ZrtpRawPacket(pkt);
             if (!zPkt.checkCrc())