Cap Channel Registrations

src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java

@@ -1209,6 +1209,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
     }
 
     public void addChannel(String channel) {
+        Preconditions.checkState(channels.size() < 128, "Cannot register channel '%s'. Too many channels registered!", channel);
         channel = StandardMessenger.validateAndCorrectChannel(channel);
         if (channels.add(channel)) {
             server.getPluginManager().callEvent(new PlayerRegisterChannelEvent(this, channel));