msgpack-rpc: handle failure to convert method arguments #2664

src/nvim/msgpack_rpc/channel.c

@@ -464,7 +464,11 @@ static void handle_request(Channel *channel, msgpack_object *request)
   }
 
   Array args = ARRAY_DICT_INIT;
-  msgpack_rpc_to_array(msgpack_rpc_args(request), &args);
+  if (!msgpack_rpc_to_array(msgpack_rpc_args(request), &args)) {
+    handler.fn = msgpack_rpc_handle_invalid_arguments;
+    handler.defer = false;
+  }
+
   bool defer = (!kv_size(channel->call_stack) && handler.defer);
   RequestEvent *event_data = xmalloc(sizeof(RequestEvent));
   event_data->channel = channel;

src/nvim/msgpack_rpc/helpers.c

@@ -306,6 +306,17 @@ Object msgpack_rpc_handle_missing_method(uint64_t channel_id,
   return NIL;
 }
 
+/// Handler executed when malformated arguments are passed
+Object msgpack_rpc_handle_invalid_arguments(uint64_t channel_id,
+                                            uint64_t request_id,
+                                            Array args,
+                                            Error *error)
+{
+  snprintf(error->msg, sizeof(error->msg), "Invalid method arguments");
+  error->set = true;
+  return NIL;
+}
+
 /// Serializes a msgpack-rpc request or notification(id == 0)
 void msgpack_rpc_serialize_request(uint64_t request_id,
                                    String method,