idna-uts46/uts46.js

A UTS #46 processing algorithm for IDNA2008 strings

/* istanbul ignore next */
(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
    define(['punycode', './idna-map'], function (punycode, idna_map) {
      return factory(punycode, idna_map);
    });
  } else if (typeof exports === 'object') {
    module.exports = factory(require('punycode'), require('./idna-map'));
  } else {
    root.uts46 = factory(root.punycode, root.idna_map);
  }
}(this, function (punycode, idna_map) {

function mapLabel(label, useStd3ASCII, transitional) {
  var mapped = [];
  for (var ch of label) {
    var cp = ch.codePointAt(0);
    var composite = idna_map.mapChar(cp);
    var flags = (composite >> 23);
    var kind = (composite >> 21) & 3;
    var index = (composite >> 5) & 0xffff;
    var length = composite & 0x1f;
    var value = idna_map.mapStr.substr(index, length);
    if (kind == 0 || (useStd3ASCII && (flags & 1))) {
      throw new Error("Illegal char " + ch);
    } else if (kind == 1) {
      mapped.push(value);
    } else if (kind == 2) {
      mapped.push(transitional ? value : ch);
    } else if (kind == 3) {
      mapped.push(ch);
    }
  }

  var newLabel = mapped.join("").normalize("NFC");
  return newLabel;
}

function process(domain, transitional, useStd3ASCII) {
  if (useStd3ASCII === undefined)
      useStd3ASCII = false;
  var mappedIDNA = mapLabel(domain, useStd3ASCII, transitional);

  // Step 3. Break
  var labels = mappedIDNA.split(".");

  // Step 4. Convert/Validate
  labels = labels.map(function (label) {
    if (label.startsWith("xn--")) {
      label = punycode.decode(label.substring(4));
      validateLabel(label, useStd3ASCII, false);
    } else {
      validateLabel(label, useStd3ASCII, transitional);
    }
    return label;
  });

  return labels.join(".");
}

function validateLabel(label, useStd3ASCII, transitional) {
  // 2. The label must not contain a U+002D HYPHEN-MINUS character in both the
  // third position and fourth positions.
  if (label[2] == '-' && label[3] == '-')
    throw new Error("Failed to validate " + label);

  // 3. The label must neither begin nor end with a U+002D HYPHEN-MINUS
  // character.
  if (label.startsWith('-') || label.endsWith('-'))
    throw new Error("Failed to validate " + label);

  // 4. The label must not contain a U+002E ( . ) FULL STOP.
  if (label.includes('.'))
    throw new Error("Failed to validate " + label);

  if (mapLabel(label, useStd3ASCII, transitional) != label)
    throw new Error("Failed to validate " + label);

  // 5. The label must not begin with a combining mark, that is:
  // General_Category=Mark.
  var ch = label.codePointAt(0);
  if (idna_map.mapChar(ch) & (0x2 << 23))
    throw new Error("Label contains illegal character: " + ch);
}

function toAscii(domain, options) {
  if (options === undefined)
    options = { };
  var transitional = 'transitional' in options ? options.transitional : true;
  var useStd3ASCII = 'useStd3ASCII' in options ? options.useStd3ASCII : false;
  var verifyDnsLength = 'verifyDnsLength' in options ? options.verifyDnsLength : false;
  var labels = process(domain, transitional, useStd3ASCII).split('.');
  var asciiLabels = labels.map(punycode.toASCII);
  var asciiString = asciiLabels.join('.');
  if (verifyDnsLength) {
    if (asciiString.length < 1 || asciiString.length > 253) {
      throw new Error("DNS name has wrong length: " + asciiString);
    }
    for (var label of asciiLabels) {
      if (label.length < 1 || label.length > 63)
        throw new Error("DNS label has wrong length: " + label);
    }
  }
  return asciiString;
}

function toUnicode(domain, options) {
  if (options === undefined)
    options = { };
  var useStd3ASCII = 'useStd3ASCII' in options ? options.useStd3ASCII : false;
  return process(domain, false, useStd3ASCII);
}

return {
  toUnicode: toUnicode,
  toAscii: toAscii,
};
}));