if (proto == NULL) {
response = MHD_create_response_from_buffer(0, NULL, MHD_RESPMEM_PERSISTENT);
MHD_queue_response(con, MHD_HTTP_PRECONDITION_FAILED, response);
if (proto == NULL) {
response = MHD_create_response_from_buffer(0, NULL, MHD_RESPMEM_PERSISTENT);
MHD_queue_response(con, MHD_HTTP_PRECONDITION_FAILED, response);