115 lines
3.1 KiB
JavaScript
115 lines
3.1 KiB
JavaScript
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import {asciiAlphanumeric} from 'micromark-util-character'
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import {encode} from 'micromark-util-encode'
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/**
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* Make a value safe for injection as a URL.
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*
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* This encodes unsafe characters with percent-encoding and skips already
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* encoded sequences (see `normalizeUri`).
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* Further unsafe characters are encoded as character references (see
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* `micromark-util-encode`).
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*
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* A regex of allowed protocols can be given, in which case the URL is
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* sanitized.
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* For example, `/^(https?|ircs?|mailto|xmpp)$/i` can be used for `a[href]`, or
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* `/^https?$/i` for `img[src]` (this is what `github.com` allows).
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* If the URL includes an unknown protocol (one not matched by `protocol`, such
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* as a dangerous example, `javascript:`), the value is ignored.
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*
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* @param {string | null | undefined} url
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* URI to sanitize.
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* @param {RegExp | null | undefined} [protocol]
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* Allowed protocols.
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* @returns {string}
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* Sanitized URI.
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*/
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export function sanitizeUri(url, protocol) {
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const value = encode(normalizeUri(url || ''))
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if (!protocol) {
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return value
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}
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const colon = value.indexOf(':')
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const questionMark = value.indexOf('?')
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const numberSign = value.indexOf('#')
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const slash = value.indexOf('/')
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if (
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// If there is no protocol, it’s relative.
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colon < 0 ||
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// If the first colon is after a `?`, `#`, or `/`, it’s not a protocol.
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(slash > -1 && colon > slash) ||
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(questionMark > -1 && colon > questionMark) ||
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(numberSign > -1 && colon > numberSign) ||
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// It is a protocol, it should be allowed.
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protocol.test(value.slice(0, colon))
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) {
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return value
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}
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return ''
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}
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/**
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* Normalize a URL.
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*
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* Encode unsafe characters with percent-encoding, skipping already encoded
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* sequences.
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*
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* @param {string} value
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* URI to normalize.
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* @returns {string}
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* Normalized URI.
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*/
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export function normalizeUri(value) {
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/** @type {Array<string>} */
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const result = []
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let index = -1
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let start = 0
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let skip = 0
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while (++index < value.length) {
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const code = value.charCodeAt(index)
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/** @type {string} */
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let replace = ''
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// A correct percent encoded value.
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if (
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code === 37 &&
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asciiAlphanumeric(value.charCodeAt(index + 1)) &&
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asciiAlphanumeric(value.charCodeAt(index + 2))
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) {
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skip = 2
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}
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// ASCII.
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else if (code < 128) {
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if (!/[!#$&-;=?-Z_a-z~]/.test(String.fromCharCode(code))) {
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replace = String.fromCharCode(code)
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}
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}
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// Astral.
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else if (code > 55_295 && code < 57_344) {
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const next = value.charCodeAt(index + 1)
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// A correct surrogate pair.
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if (code < 56_320 && next > 56_319 && next < 57_344) {
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replace = String.fromCharCode(code, next)
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skip = 1
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}
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// Lone surrogate.
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else {
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replace = '\uFFFD'
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}
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}
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// Unicode.
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else {
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replace = String.fromCharCode(code)
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}
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if (replace) {
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result.push(value.slice(start, index), encodeURIComponent(replace))
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start = index + skip + 1
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replace = ''
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}
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if (skip) {
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index += skip
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skip = 0
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}
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}
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return result.join('') + value.slice(start)
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}
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