158 lines
3.9 KiB
JavaScript
158 lines
3.9 KiB
JavaScript
'use strict';
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const {
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unassigned_code_points,
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commonly_mapped_to_nothing,
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non_ASCII_space_characters,
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prohibited_characters,
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bidirectional_r_al,
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bidirectional_l,
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} = require('./lib/memory-code-points');
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module.exports = saslprep;
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// 2.1. Mapping
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/**
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* non-ASCII space characters [StringPrep, C.1.2] that can be
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* mapped to SPACE (U+0020)
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*/
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const mapping2space = non_ASCII_space_characters;
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/**
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* the "commonly mapped to nothing" characters [StringPrep, B.1]
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* that can be mapped to nothing.
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*/
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const mapping2nothing = commonly_mapped_to_nothing;
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// utils
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const getCodePoint = character => character.codePointAt(0);
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const first = x => x[0];
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const last = x => x[x.length - 1];
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/**
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* Convert provided string into an array of Unicode Code Points.
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* Based on https://stackoverflow.com/a/21409165/1556249
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* and https://www.npmjs.com/package/code-point-at.
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* @param {string} input
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* @returns {number[]}
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*/
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function toCodePoints(input) {
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const codepoints = [];
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const size = input.length;
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for (let i = 0; i < size; i += 1) {
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const before = input.charCodeAt(i);
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if (before >= 0xd800 && before <= 0xdbff && size > i + 1) {
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const next = input.charCodeAt(i + 1);
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if (next >= 0xdc00 && next <= 0xdfff) {
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codepoints.push((before - 0xd800) * 0x400 + next - 0xdc00 + 0x10000);
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i += 1;
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continue;
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}
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}
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codepoints.push(before);
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}
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return codepoints;
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}
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/**
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* SASLprep.
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* @param {string} input
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* @param {Object} opts
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* @param {boolean} opts.allowUnassigned
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* @returns {string}
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*/
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function saslprep(input, opts = {}) {
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if (typeof input !== 'string') {
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throw new TypeError('Expected string.');
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}
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if (input.length === 0) {
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return '';
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}
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// 1. Map
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const mapped_input = toCodePoints(input)
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// 1.1 mapping to space
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.map(character => (mapping2space.get(character) ? 0x20 : character))
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// 1.2 mapping to nothing
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.filter(character => !mapping2nothing.get(character));
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// 2. Normalize
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const normalized_input = String.fromCodePoint
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.apply(null, mapped_input)
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.normalize('NFKC');
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const normalized_map = toCodePoints(normalized_input);
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// 3. Prohibit
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const hasProhibited = normalized_map.some(character =>
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prohibited_characters.get(character)
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);
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if (hasProhibited) {
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throw new Error(
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'Prohibited character, see https://tools.ietf.org/html/rfc4013#section-2.3'
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);
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}
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// Unassigned Code Points
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if (opts.allowUnassigned !== true) {
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const hasUnassigned = normalized_map.some(character =>
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unassigned_code_points.get(character)
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);
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if (hasUnassigned) {
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throw new Error(
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'Unassigned code point, see https://tools.ietf.org/html/rfc4013#section-2.5'
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);
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}
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}
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// 4. check bidi
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const hasBidiRAL = normalized_map.some(character =>
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bidirectional_r_al.get(character)
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);
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const hasBidiL = normalized_map.some(character =>
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bidirectional_l.get(character)
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);
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// 4.1 If a string contains any RandALCat character, the string MUST NOT
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// contain any LCat character.
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if (hasBidiRAL && hasBidiL) {
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throw new Error(
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'String must not contain RandALCat and LCat at the same time,' +
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' see https://tools.ietf.org/html/rfc3454#section-6'
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);
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}
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/**
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* 4.2 If a string contains any RandALCat character, a RandALCat
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* character MUST be the first character of the string, and a
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* RandALCat character MUST be the last character of the string.
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*/
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const isFirstBidiRAL = bidirectional_r_al.get(
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getCodePoint(first(normalized_input))
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);
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const isLastBidiRAL = bidirectional_r_al.get(
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getCodePoint(last(normalized_input))
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);
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if (hasBidiRAL && !(isFirstBidiRAL && isLastBidiRAL)) {
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throw new Error(
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'Bidirectional RandALCat character must be the first and the last' +
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' character of the string, see https://tools.ietf.org/html/rfc3454#section-6'
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);
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}
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return normalized_input;
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}
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