Improved handling of Internationalized Domain Names in punycode

vendors/mathiasbynens/punycode.js

@@ -0,0 +1,395 @@
+/**
+ * Modified version of https://github.com/mathiasbynens/punycode.js
+ */
+
+(() => {
+
+'use strict';
+
+const
+	/** Highest positive signed 32-bit float value */
+	maxInt = 2147483647, // aka. 0x7FFFFFFF or 2^31-1
+
+	/** Bootstring parameters */
+	base = 36,
+	tMin = 1,
+	tMax = 26,
+	skew = 38,
+	damp = 700,
+	initialBias = 72,
+	initialN = 128, // 0x80
+	delimiter = '-', // '\x2D'
+
+	/** Regular expressions */
+	regexPunycode = /^xn--/,
+	regexNonASCII = /[^\0-\x7F]/, // Note: U+007F DEL is excluded too.
+	regexSeparators = /[\x2E\u3002\uFF0E\uFF61]/g, // RFC 3490 separators
+
+	/** Error messages */
+	errors = {
+		'overflow': 'Overflow: input needs wider integers to process',
+		'not-basic': 'Illegal input >= 0x80 (not a basic code point)',
+		'invalid-input': 'Invalid input'
+	},
+
+	/** Convenience shortcuts */
+	baseMinusTMin = base - tMin,
+	floor = Math.floor,
+	stringFromCharCode = String.fromCharCode,
+
+	/*--------------------------------------------------------------------------*/
+
+	/**
+	 * A generic error utility function.
+	 * @private
+	 * @param {String} type The error type.
+	 * @returns {Error} Throws a `RangeError` with the applicable error message.
+	 */
+	error = type => {
+		throw new RangeError(errors[type])
+	},
+
+	/**
+	 * A simple `Array#map`-like wrapper to work with domain name strings or email
+	 * addresses.
+	 * @private
+	 * @param {String} domain The domain name or email address.
+	 * @param {Function} callback The function that gets called for every
+	 * character.
+	 * @returns {String} A new string of characters returned by the callback
+	 * function.
+	 */
+	mapDomain = (domain, callback) => {
+		// In email addresses, only the domain name should be punycoded.
+		// Leave the local part (i.e. everything up to `@`) intact.
+		const parts = domain.split('@');
+		parts.push(
+			parts.pop()
+			.split(regexSeparators)
+			.map(label => callback(label))
+			.join('.')
+		);
+		return parts.join('@');
+	},
+
+	/**
+	 * Creates an array containing the numeric code points of each Unicode
+	 * character in the string. While JavaScript uses UCS-2 internally,
+	 * this function will convert a pair of surrogate halves (each of which
+	 * UCS-2 exposes as separate characters) into a single code point,
+	 * matching UTF-16.
+	 * @see <https://mathiasbynens.be/notes/javascript-encoding>
+	 * @name decode
+	 * @param {String} string The Unicode input string (UCS-2).
+	 * @returns {Array} The new array of code points.
+	 */
+	ucs2decode = string => {
+		const output = [];
+		let counter = 0;
+		const length = string.length;
+		while (counter < length) {
+			const value = string.charCodeAt(counter++);
+			if (value >= 0xD800 && value <= 0xDBFF && counter < length) {
+				// It's a high surrogate, and there is a next character.
+				const extra = string.charCodeAt(counter++);
+				if ((extra & 0xFC00) == 0xDC00) { // Low surrogate.
+					output.push(((value & 0x3FF) << 10) + (extra & 0x3FF) + 0x10000);
+				} else {
+					// It's an unmatched surrogate; only append this code unit, in case the
+					// next code unit is the high surrogate of a surrogate pair.
+					output.push(value);
+					counter--;
+				}
+			} else {
+				output.push(value);
+			}
+		}
+		return output;
+	},
+
+	/**
+	 * Converts a basic code point into a digit/integer.
+	 * @see `digitToBasic()`
+	 * @private
+	 * @param {Number} codePoint The basic numeric code point value.
+	 * @returns {Number} The numeric value of a basic code point (for use in
+	 * representing integers) in the range `0` to `base - 1`, or `base` if
+	 * the code point does not represent a value.
+	 */
+	basicToDigit = codePoint => {
+		if (codePoint >= 0x30 && codePoint < 0x3A) {
+			return 26 + (codePoint - 0x30);
+		}
+		if (codePoint >= 0x41 && codePoint < 0x5B) {
+			return codePoint - 0x41;
+		}
+		if (codePoint >= 0x61 && codePoint < 0x7B) {
+			return codePoint - 0x61;
+		}
+		return base;
+	},
+
+	/**
+	 * Converts a digit/integer into a basic code point.
+	 * @see `basicToDigit()`
+	 * @private
+	 * @param {Number} digit The numeric value of a basic code point.
+	 * @returns {Number} The basic code point whose value (when used for
+	 * representing integers) is `digit`, which needs to be in the range
+	 * `0` to `base - 1`. If `flag` is non-zero, the uppercase form is
+	 * used; else, the lowercase form is used. The behavior is undefined
+	 * if `flag` is non-zero and `digit` has no uppercase form.
+	 */
+	digitToBasic = (digit, flag) =>
+		//  0..25 map to ASCII a..z or A..Z
+		// 26..35 map to ASCII 0..9
+		digit + 22 + 75 * (digit < 26) - ((flag != 0) << 5),
+
+	/**
+	 * Bias adaptation function as per section 3.4 of RFC 3492.
+	 * https://tools.ietf.org/html/rfc3492#section-3.4
+	 * @private
+	 */
+	adapt = (delta, numPoints, firstTime) => {
+		let k = 0;
+		delta = firstTime ? floor(delta / damp) : delta >> 1;
+		delta += floor(delta / numPoints);
+		for (/* no initialization */; delta > baseMinusTMin * tMax >> 1; k += base) {
+			delta = floor(delta / baseMinusTMin);
+		}
+		return floor(k + (baseMinusTMin + 1) * delta / (delta + skew));
+	},
+
+	/**
+	 * Converts a Punycode string of ASCII-only symbols to a string of Unicode
+	 * symbols.
+	 * @memberOf punycode
+	 * @param {String} input The Punycode string of ASCII-only symbols.
+	 * @returns {String} The resulting string of Unicode symbols.
+	 */
+	decode = input => {
+		// Don't use UCS-2.
+		const output = [];
+		const inputLength = input.length;
+		let i = 0;
+		let n = initialN;
+		let bias = initialBias;
+
+		// Handle the basic code points: let `basic` be the number of input code
+		// points before the last delimiter, or `0` if there is none, then copy
+		// the first basic code points to the output.
+
+		let basic = input.lastIndexOf(delimiter);
+		if (basic < 0) {
+			basic = 0;
+		}
+
+		for (let j = 0; j < basic; ++j) {
+			// if it's not a basic code point
+			if (input.charCodeAt(j) >= 0x80) {
+				error('not-basic');
+			}
+			output.push(input.charCodeAt(j));
+		}
+
+		// Main decoding loop: start just after the last delimiter if any basic code
+		// points were copied; start at the beginning otherwise.
+
+		for (let index = basic > 0 ? basic + 1 : 0; index < inputLength; /* no final expression */) {
+
+			// `index` is the index of the next character to be consumed.
+			// Decode a generalized variable-length integer into `delta`,
+			// which gets added to `i`. The overflow checking is easier
+			// if we increase `i` as we go, then subtract off its starting
+			// value at the end to obtain `delta`.
+			const oldi = i;
+			for (let w = 1, k = base; /* no condition */; k += base) {
+
+				if (index >= inputLength) {
+					error('invalid-input');
+				}
+
+				const digit = basicToDigit(input.charCodeAt(index++));
+
+				if (digit >= base) {
+					error('invalid-input');
+				}
+				if (digit > floor((maxInt - i) / w)) {
+					error('overflow');
+				}
+
+				i += digit * w;
+				const t = k <= bias ? tMin : (k >= bias + tMax ? tMax : k - bias);
+
+				if (digit < t) {
+					break;
+				}
+
+				const baseMinusT = base - t;
+				if (w > floor(maxInt / baseMinusT)) {
+					error('overflow');
+				}
+
+				w *= baseMinusT;
+
+			}
+
+			const out = output.length + 1;
+			bias = adapt(i - oldi, out, oldi == 0);
+
+			// `i` was supposed to wrap around from `out` to `0`,
+			// incrementing `n` each time, so we'll fix that now:
+			if (floor(i / out) > maxInt - n) {
+				error('overflow');
+			}
+
+			n += floor(i / out);
+			i %= out;
+
+			// Insert `n` at position `i` of the output.
+			output.splice(i++, 0, n);
+
+		}
+
+		return String.fromCodePoint(...output);
+	},
+
+	/**
+	 * Converts a string of Unicode symbols (e.g. a domain name label) to a
+	 * Punycode string of ASCII-only symbols.
+	 * @memberOf punycode
+	 * @param {String} input The string of Unicode symbols.
+	 * @returns {String} The resulting Punycode string of ASCII-only symbols.
+	 */
+	encode = input => {
+		const output = [];
+
+		// Convert the input in UCS-2 to an array of Unicode code points.
+		input = ucs2decode(input);
+
+		// Cache the length.
+		const inputLength = input.length;
+
+		// Initialize the state.
+		let n = initialN;
+		let delta = 0;
+		let bias = initialBias;
+
+		// Handle the basic code points.
+		for (const currentValue of input) {
+			if (currentValue < 0x80) {
+				output.push(stringFromCharCode(currentValue));
+			}
+		}
+
+		const basicLength = output.length;
+		let handledCPCount = basicLength;
+
+		// `handledCPCount` is the number of code points that have been handled;
+		// `basicLength` is the number of basic code points.
+
+		// Finish the basic string with a delimiter unless it's empty.
+		if (basicLength) {
+			output.push(delimiter);
+		}
+
+		// Main encoding loop:
+		while (handledCPCount < inputLength) {
+
+			// All non-basic code points < n have been handled already. Find the next
+			// larger one:
+			let m = maxInt;
+			for (const currentValue of input) {
+				if (currentValue >= n && currentValue < m) {
+					m = currentValue;
+				}
+			}
+
+			// Increase `delta` enough to advance the decoder's <n,i> state to <m,0>,
+			// but guard against overflow.
+			const handledCPCountPlusOne = handledCPCount + 1;
+			if (m - n > floor((maxInt - delta) / handledCPCountPlusOne)) {
+				error('overflow');
+			}
+
+			delta += (m - n) * handledCPCountPlusOne;
+			n = m;
+
+			for (const currentValue of input) {
+				if (currentValue < n && ++delta > maxInt) {
+					error('overflow');
+				}
+				if (currentValue === n) {
+					// Represent delta as a generalized variable-length integer.
+					let q = delta;
+					for (let k = base; /* no condition */; k += base) {
+						const t = k <= bias ? tMin : (k >= bias + tMax ? tMax : k - bias);
+						if (q < t) {
+							break;
+						}
+						const qMinusT = q - t;
+						const baseMinusT = base - t;
+						output.push(
+							stringFromCharCode(digitToBasic(t + qMinusT % baseMinusT, 0))
+						);
+						q = floor(qMinusT / baseMinusT);
+					}
+
+					output.push(stringFromCharCode(digitToBasic(q, 0)));
+					bias = adapt(delta, handledCPCountPlusOne, handledCPCount === basicLength);
+					delta = 0;
+					++handledCPCount;
+				}
+			}
+
+			++delta;
+			++n;
+
+		}
+		return output.join('');
+	};
+
+	/*--------------------------------------------------------------------------*/
+
+	/** Define the public API */
+	window.IDN = {
+		/**
+		 * A string representing the current Punycode.js version number.
+		 * @memberOf punycode
+		 * @type String
+		 */
+		version: '2.3.1',
+
+		/**
+		 * Converts a Punycode string representing a domain name or an email address
+		 * to Unicode. Only the Punycoded parts of the input will be converted, i.e.
+		 * it doesn't matter if you call it on a string that has already been
+		 * converted to Unicode.
+		 * @memberOf punycode
+		 * @param {String} input The Punycoded domain name or email address to
+		 * convert to Unicode.
+		 * @returns {String} The Unicode representation of the given Punycode
+		 * string.
+		 */
+		toUnicode: input => mapDomain(
+			input,
+			string => regexPunycode.test(string) ? decode(string.slice(4).toLowerCase()) : string
+		),
+
+		/**
+		 * Converts a Unicode string representing a domain name or an email address to
+		 * Punycode. Only the non-ASCII parts of the domain name will be converted,
+		 * i.e. it doesn't matter if you call it with a domain that's already in
+		 * ASCII.
+		 * @memberOf punycode
+		 * @param {String} input The domain name or email address to convert, as a
+		 * Unicode string.
+		 * @returns {String} The Punycode representation of the given domain name or
+		 * email address.
+		 */
+		toASCII: input => mapDomain(
+			input,
+			string => regexNonASCII.test(string) ? 'xn--' + encode(string) : string
+		)
+	};
+})();