throw error if VIAaaS tries to connect to itself

Author: creeper123123321

src/main/kotlin/com/viaversion/aas/handler/state/LoginState.kt

@@ -57,10 +57,18 @@ class LoginState : ConnectionState {
             is SetCompression -> handleCompression(handler, packet)
             is LoginAck -> handleLoginAck(handler, packet)
             is UnknownPacket -> throw StacklessException("unknown packet ${packet.id}")
+            is PluginRequest -> handlePluginRequest(handler, packet)
             else -> forward(handler, packet)
         }
     }
 
+    private fun handlePluginRequest(handler: MinecraftHandler, packet: PluginRequest) {
+        if (packet.channel == "oam:join") {
+            throw StacklessException("VIAaaS connection loop detected")
+        }
+        forward(handler, packet)
+    }
+
     private fun handleLoginAck(handler: MinecraftHandler, packet: LoginAck) {
         handler.data.setBothStates(ConfigurationState())
         forward(handler, packet)