Fix Remote Plugin Messages

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

@@ -1,5 +1,6 @@
 package de.steamwar.bungeecore.network;
 
+import de.steamwar.bungeecore.BungeeCore;
 import de.steamwar.bungeecore.listeners.BasicListener;
 import de.steamwar.network.packets.NetworkPacket;
 import net.md_5.bungee.api.config.ServerInfo;
@@ -7,12 +8,25 @@ import net.md_5.bungee.api.connection.Server;
 import net.md_5.bungee.api.event.PluginMessageEvent;
 import net.md_5.bungee.event.EventHandler;
 
+import java.net.InetSocketAddress;
+import java.util.Arrays;
+import java.util.List;
+import java.util.logging.Level;
+
 public class NetworkReceiver extends BasicListener {
 
+    private static final List<String> blockedTags = Arrays.asList("bungeecord:main", "BungeeCord", "sw:bridge");
+    private static final List<String> allowedAddresses = Arrays.asList("localhost", "127.0.0.1", "0.0.0.0");
+
     public static ServerInfo sender;
 
     @EventHandler
     public 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);
+            return;
+        }
         if(!event.getTag().equalsIgnoreCase("sw:bridge"))
             return;