Fix for Port Binding Conflicts in ArtNetClient and ArtNetServer

src/main/java/ch/bildspur/artnet/ArtNetClient.java

@@ -49,8 +49,7 @@ public ArtNetClient(ArtNetBuffer inputBuffer, int serverPort, int clientPort) {
      * Start client with default arguments (listen on broadcast).
      */
     public void start() {
-        // use default network interface
-        this.start((InetAddress)null);
+        this.start(null, true); // default to static binding (receiver mode)
     }
 
     /**
@@ -60,7 +59,7 @@ public void start() {
     public void start(String networkInterfaceAddress)
     {
         try {
-            this.start(InetAddress.getByName(networkInterfaceAddress));
+            this.start(InetAddress.getByName(networkInterfaceAddress), inputBuffer != null);
         } catch (UnknownHostException e) {
             e.printStackTrace();
         }
@@ -71,6 +70,15 @@ public void start(String networkInterfaceAddress)
      * @param networkInterfaceAddress Network interface address to listen to.
      */
     public void start(InetAddress networkInterfaceAddress) {
+        this.start(networkInterfaceAddress, inputBuffer != null);
+    }
+
+    /**
+     * Start client with specific network interface address and receiver mode.
+     * @param networkInterfaceAddress Network interface address to listen to.
+     * @param isReceiver If true, the client will bind to the specified port to receive data.
+     */
+    public void start(InetAddress networkInterfaceAddress, boolean isReceiver) {
         if (isRunning)
             return;
 
@@ -87,14 +95,22 @@ public void artNetPacketReceived(ArtNetPacket packet) {
                         }
                     });
 
-            server.start(networkInterfaceAddress);
+            server.start(networkInterfaceAddress, isReceiver);
 
             isRunning = true;
         } catch (SocketException | ArtNetException e) {
             e.printStackTrace();
         }
     }
 
+    /**
+     * Start client with receiver mode.
+     * @param isReceiver If true, the client will bind to the specified port to receive data.
+     */
+    public void start(boolean isReceiver) {
+        this.start((InetAddress) null, isReceiver);
+    }
+
     /**
      * Stops the client and udp server.
      */

src/main/java/ch/bildspur/artnet/ArtNetServer.java

@@ -158,10 +158,14 @@ private void setBufferSize(int size) {
     }
 
     public void start() throws SocketException, ArtNetException {
-        start(null);
+        start(null, true);
     }
 
     public void start(InetAddress networkAddress) throws SocketException, ArtNetException {
+        start(networkAddress, true);
+    }
+
+    public void start(InetAddress networkAddress, boolean isReceiver) throws SocketException, ArtNetException {
         if (broadCastAddress == null) {
             setBroadcastAddress(DEFAULT_BROADCAST_IP);
         }
@@ -170,12 +174,16 @@ public void start(InetAddress networkAddress) throws SocketException, ArtNetExce
             socket.setReuseAddress(true);
             socket.setBroadcast(true);
 
-            if (networkAddress == null)
-                networkAddress = socket.getLocalAddress();
+            if (isReceiver) {
+                if (networkAddress == null)
+                    networkAddress = socket.getLocalAddress();
 
-            socket.bind(new InetSocketAddress(networkAddress, port));
+                socket.bind(new InetSocketAddress(networkAddress, port));
+                logger.info("Art-Net server started at: " + networkAddress.getHostAddress() + ":" + port);
+            } else {
+                logger.info("Art-Net server started as sender using ephemeral port.");
+            }
 
-            logger.info("Art-Net server started at: " + networkAddress.getHostAddress() + ":" + port);
             for (ArtNetServerListener l : listeners) {
                 l.artNetServerStarted(this);
             }