44 lines
1.1 KiB
JavaScript
44 lines
1.1 KiB
JavaScript
import * as crypto from 'node:crypto';
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const hashes = Object.create(null);
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//TODO shorter?
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const hash_length = 12;
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/**
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* replaces +/= in base64 output so they don't interfere
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*
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* @param {string} input
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* @returns {string} base64 hash safe to use in any context
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*/
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export function safeBase64Hash(input) {
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if (hashes[input]) {
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return hashes[input];
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}
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//TODO if performance really matters, use a faster one like xx-hash etc.
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// should be evenly distributed because short input length and similarities in paths could cause collisions otherwise
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// OR DON'T USE A HASH AT ALL, what about a simple counter?
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const md5 = crypto.createHash('md5');
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md5.update(input);
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const hash = toSafe(md5.digest('base64')).slice(0, hash_length);
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hashes[input] = hash;
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return hash;
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}
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/** @type {Record<string, string>} */
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const replacements = {
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'+': '-',
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'/': '_',
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'=': ''
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};
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const replaceRE = new RegExp(`[${Object.keys(replacements).join('')}]`, 'g');
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/**
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* @param {string} base64
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* @returns {string}
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*/
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function toSafe(base64) {
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return base64.replace(replaceRE, (x) => replacements[x]);
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}
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