index.js
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'use strict'
const {
unassigned_code_points,
commonly_mapped_to_nothing,
non_ASCII_space_characters,
prohibited_characters,
bidirectional_r_al,
bidirectional_l,
} = require('./lib/memory-code-points')
module.exports = saslprep
// 2.1. Mapping
/**
* non-ASCII space characters [StringPrep, C.1.2] that can be
* mapped to SPACE (U+0020)
*/
const mapping2space = non_ASCII_space_characters
/**
* the "commonly mapped to nothing" characters [StringPrep, B.1]
* that can be mapped to nothing.
*/
const mapping2nothing = commonly_mapped_to_nothing
// utils
const getCodePoint = character => character.codePointAt(0)
const first = x => x[0]
const last = x => x[x.length - 1]
/**
* SASLprep.
* @param {string} input
* @param {object} opts
* @param {boolean} opts.allowUnassigned
*/
function saslprep(input, opts = {}) {
if (typeof input !== 'string') {
throw new TypeError('Expected string.')
}
if (input.length === 0) {
return ''
}
// 1. Map
const mapped_input = input
.split('')
.map(getCodePoint)
// 1.1 mapping to space
.map(character => (mapping2space.get(character) ? 0x20 : character))
// 1.2 mapping to nothing
.filter(character => !mapping2nothing.get(character))
// 2. Normalize
const normalized_input = String.fromCodePoint(...mapped_input).normalize('NFKC')
const normalized_map = normalized_input.split('').map(getCodePoint)
// 3. Prohibit
const hasProhibited = normalized_map.some(character =>
prohibited_characters.get(character)
)
if (hasProhibited) {
throw new Error(
'Prohibited character, see https://tools.ietf.org/html/rfc4013#section-2.3'
)
}
// Unassigned Code Points
if (opts.allowUnassigned !== true) {
const hasUnassigned = normalized_map.some(character =>
unassigned_code_points.get(character)
)
if (hasUnassigned) {
throw new Error(
'Unassigned code point, see https://tools.ietf.org/html/rfc4013#section-2.5'
)
}
}
// 4. check bidi
const hasBidiRAL = normalized_map
.some((character) => bidirectional_r_al.get(character))
const hasBidiL = normalized_map
.some((character) => bidirectional_l.get(character))
// 4.1 If a string contains any RandALCat character, the string MUST NOT
// contain any LCat character.
if (hasBidiRAL && hasBidiL) {
throw new Error(
'String must not contain RandALCat and LCat at the same time,' +
' see https://tools.ietf.org/html/rfc3454#section-6'
)
}
/**
* 4.2 If a string contains any RandALCat character, a RandALCat
* character MUST be the first character of the string, and a
* RandALCat character MUST be the last character of the string.
*/
const isFirstBidiRAL = bidirectional_r_al.get(getCodePoint(first(normalized_input)))
const isLastBidiRAL = bidirectional_r_al.get(getCodePoint(last(normalized_input)))
if (hasBidiRAL && !(isFirstBidiRAL && isLastBidiRAL)) {
throw new Error(
'Bidirectional RandALCat character must be the first and the last' +
' character of the string, see https://tools.ietf.org/html/rfc3454#section-6'
)
}
return normalized_input
}