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optimize extractUrlFromMfm

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Hazelnoot 2025-05-20 22:33:14 -04:00
parent dc1adcc491
commit e74fde8b31
1 changed files with 24 additions and 12 deletions
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36
packages/frontend/src/utility/extract-url-from-mfm.ts
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@ -4,22 +4,34 @@
*/
import * as mfm from '@transfem-org/sfm-js';
import { unique } from '@/utility/array.js';
// unique without hash
// [ http://a/#1, http://a/#2, http://b/#3 ] => [ http://a/#1, http://b/#3 ]
const removeHash = (x: string) => x.replace(/#[^#]*$/, '');
const removeHash = (x: string) => {
if (URL.canParse(x)) {
const url = new URL(x);
url.hash = '';
return url.toString();
} else {
return x.replace(/#[^#]*$/, '');
}
};
// TODO this is O(n^2) which could introduce a frontend DoS with a large enough character limit
export function extractUrlFromMfm(nodes: mfm.MfmNode[], respectSilentFlag = true): string[] {
const urlNodes = mfm.extract(nodes, (node) => {
return (node.type === 'url') || (node.type === 'link' && (!respectSilentFlag || !node.props.silent));
});
const urls: string[] = unique(urlNodes.map(x => x.props.url));
const urls = new Map<string, string>();
return urls.reduce((array, url) => {
const urlWithoutHash = removeHash(url);
if (!array.map(x => removeHash(x)).includes(urlWithoutHash)) array.push(url);
return array;
}, [] as string[]);
// Single iteration pass to avoid potential DoS in maliciously-constructed notes.
for (const node of nodes) {
if ((node.type === 'url') || (node.type === 'link' && (!respectSilentFlag || !node.props.silent))) {
const url = (node as mfm.MfmUrl | mfm.MfmLink).props.url;
const key = removeHash(url);
// Keep the first match only, to preserve existing behavior.
if (!urls.has(key)) {
urls.set(key, url);
}
}
}
return Array.from(urls.values());
}