169 lines
5.1 KiB
JavaScript
169 lines
5.1 KiB
JavaScript
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'use strict';
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// based on https://github.com/bestiejs/punycode.js/blob/master/punycode.js
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var maxInt = 2147483647; // aka. 0x7FFFFFFF or 2^31-1
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var base = 36;
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var tMin = 1;
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var tMax = 26;
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var skew = 38;
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var damp = 700;
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var initialBias = 72;
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var initialN = 128; // 0x80
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var delimiter = '-'; // '\x2D'
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var regexNonASCII = /[^\0-\u007E]/; // non-ASCII chars
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var regexSeparators = /[.\u3002\uFF0E\uFF61]/g; // RFC 3490 separators
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var OVERFLOW_ERROR = 'Overflow: input needs wider integers to process';
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var baseMinusTMin = base - tMin;
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var floor = Math.floor;
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var stringFromCharCode = String.fromCharCode;
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/**
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* Creates an array containing the numeric code points of each Unicode
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* character in the string. While JavaScript uses UCS-2 internally,
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* this function will convert a pair of surrogate halves (each of which
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* UCS-2 exposes as separate characters) into a single code point,
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* matching UTF-16.
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*/
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var ucs2decode = function (string) {
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var output = [];
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var counter = 0;
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var length = string.length;
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while (counter < length) {
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var value = string.charCodeAt(counter++);
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if (value >= 0xD800 && value <= 0xDBFF && counter < length) {
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// It's a high surrogate, and there is a next character.
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var extra = string.charCodeAt(counter++);
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if ((extra & 0xFC00) == 0xDC00) { // Low surrogate.
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output.push(((value & 0x3FF) << 10) + (extra & 0x3FF) + 0x10000);
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} else {
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// It's an unmatched surrogate; only append this code unit, in case the
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// next code unit is the high surrogate of a surrogate pair.
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output.push(value);
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counter--;
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}
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} else {
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output.push(value);
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}
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}
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return output;
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};
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/**
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* Converts a digit/integer into a basic code point.
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*/
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var digitToBasic = function (digit) {
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// 0..25 map to ASCII a..z or A..Z
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// 26..35 map to ASCII 0..9
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return digit + 22 + 75 * (digit < 26);
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};
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/**
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* Bias adaptation function as per section 3.4 of RFC 3492.
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* https://tools.ietf.org/html/rfc3492#section-3.4
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*/
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var adapt = function (delta, numPoints, firstTime) {
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var k = 0;
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delta = firstTime ? floor(delta / damp) : delta >> 1;
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delta += floor(delta / numPoints);
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for (; delta > baseMinusTMin * tMax >> 1; k += base) {
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delta = floor(delta / baseMinusTMin);
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}
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return floor(k + (baseMinusTMin + 1) * delta / (delta + skew));
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};
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/**
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* Converts a string of Unicode symbols (e.g. a domain name label) to a
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* Punycode string of ASCII-only symbols.
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*/
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// eslint-disable-next-line max-statements
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var encode = function (input) {
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var output = [];
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// Convert the input in UCS-2 to an array of Unicode code points.
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input = ucs2decode(input);
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// Cache the length.
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var inputLength = input.length;
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// Initialize the state.
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var n = initialN;
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var delta = 0;
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var bias = initialBias;
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var i, currentValue;
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// Handle the basic code points.
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for (i = 0; i < input.length; i++) {
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currentValue = input[i];
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if (currentValue < 0x80) {
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output.push(stringFromCharCode(currentValue));
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}
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}
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var basicLength = output.length; // number of basic code points.
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var handledCPCount = basicLength; // number of code points that have been handled;
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// Finish the basic string with a delimiter unless it's empty.
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if (basicLength) {
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output.push(delimiter);
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}
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// Main encoding loop:
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while (handledCPCount < inputLength) {
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// All non-basic code points < n have been handled already. Find the next larger one:
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var m = maxInt;
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for (i = 0; i < input.length; i++) {
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currentValue = input[i];
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if (currentValue >= n && currentValue < m) {
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m = currentValue;
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}
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}
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// Increase `delta` enough to advance the decoder's <n,i> state to <m,0>, but guard against overflow.
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var handledCPCountPlusOne = handledCPCount + 1;
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if (m - n > floor((maxInt - delta) / handledCPCountPlusOne)) {
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throw RangeError(OVERFLOW_ERROR);
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}
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delta += (m - n) * handledCPCountPlusOne;
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n = m;
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for (i = 0; i < input.length; i++) {
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currentValue = input[i];
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if (currentValue < n && ++delta > maxInt) {
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throw RangeError(OVERFLOW_ERROR);
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}
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if (currentValue == n) {
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// Represent delta as a generalized variable-length integer.
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var q = delta;
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for (var k = base; /* no condition */; k += base) {
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var t = k <= bias ? tMin : (k >= bias + tMax ? tMax : k - bias);
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if (q < t) break;
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var qMinusT = q - t;
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var baseMinusT = base - t;
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output.push(stringFromCharCode(digitToBasic(t + qMinusT % baseMinusT)));
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q = floor(qMinusT / baseMinusT);
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}
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output.push(stringFromCharCode(digitToBasic(q)));
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bias = adapt(delta, handledCPCountPlusOne, handledCPCount == basicLength);
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delta = 0;
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++handledCPCount;
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}
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}
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++delta;
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++n;
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}
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return output.join('');
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};
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module.exports = function (input) {
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var encoded = [];
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var labels = input.toLowerCase().replace(regexSeparators, '\u002E').split('.');
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var i, label;
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for (i = 0; i < labels.length; i++) {
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label = labels[i];
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encoded.push(regexNonASCII.test(label) ? 'xn--' + encode(label) : label);
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}
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return encoded.join('.');
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};
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