message: swoole_async_dns_lookup check parameter.
diff: @@ -755,6 +755,12 @@ PHP_FUNCTION(swoole_async_dns_lookup)
  return;
  }
  + if (Z_TYPE_P(domain) != IS_STRING)
  + {
  + swoole_php_fatal_error(E_WARNING, "invalid domain name.");
  + RETURN_FALSE;
  + }
  +
  if (Z_STRLEN_P(domain) == 0)
  {
  swoole_php_fatal_error(E_WARNING, "domain name empty.");
  