Fix concurrency, fix cast

Signed-off-by: Lixfel <agga-games@gmx.de>

src/de/steamwar/bungeecore/network/NetworkReceiver.java

@@ -41,7 +41,7 @@ public class NetworkReceiver extends BasicListener {
     public static ServerInfo sender;
 
     @EventHandler(priority = EventPriority.HIGHEST)
-    public void onPluginMessage(PluginMessageEvent event) {
+    public synchronized void onPluginMessage(PluginMessageEvent event) {
         if (blockedTags.contains(event.getTag()) && !allowedAddresses.contains(((InetSocketAddress) event.getSender().getSocketAddress()).getHostString())) {
             BungeeCore.log(Level.SEVERE, ((InetSocketAddress) event.getSender().getSocketAddress()).getHostString() + " tried to send a plugin message with tag " + event.getTag());
             event.setCancelled(true);
@@ -54,7 +54,7 @@ public class NetworkReceiver extends BasicListener {
         if(!(event.getSender() instanceof Server))
             return;
 
-        sender = (ServerInfo) event.getSender();
+        sender = ((Server) event.getSender()).getInfo();
         NetworkPacket.handle(event.getData());
         sender = null;
     }