function validateLabel(label, processing_option) {
  if (label.substr(0, 4) === "xn--") {
    label = punycode.toUnicode(label);
    processing_option = PROCESSING_OPTIONS.NONTRANSITIONAL;
  }

  var error = false;

  if (normalize(label) !== label ||
      (label[3] === "-" && label[4] === "-") ||
      label[0] === "-" || label[label.length - 1] === "-" ||
      label.indexOf(".") !== -1 ||
      label.search(combiningMarksRegex) === 0) {
    error = true;
  }

  var len = countSymbols(label);
  for (var i = 0; i < len; ++i) {
    var status = findStatus(label.codePointAt(i));
    if ((processing === PROCESSING_OPTIONS.TRANSITIONAL && status[1] !== "valid") ||
        (processing === PROCESSING_OPTIONS.NONTRANSITIONAL &&
         status[1] !== "valid" && status[1] !== "deviation")) {
      error = true;
      break;
    }
  }

  return {
    label: label,
    error: error
  };
}
Normalize a mime type.
If it's a shorthand, expand it to a valid mime type.

In general, you probably want:

  var type = is(req, ['urlencoded', 'json', 'multipart']);

Then use the appropriate body parsers.
These three are the most common request body types
and are thus ensured to work.

@param {String} type
@private