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fix: prevent linking text with directional change char #388

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fix: prevent linking text with directional change char #388

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3 changes: 2 additions & 1 deletion src/parser/parse-matches.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ import { UrlMatch, UrlMatchType } from '../match/url-match';
import { Match } from '../match/match';
import { remove, assertNever } from '../utils';
import {
hasDirectionalChar,
httpSchemeRe,
isDomainLabelChar,
isDomainLabelStartChar,
Expand Down Expand Up @@ -411,7 +412,7 @@ export function parseMatches(text: string, args: ParseMatchesArgs): Match[] {
} else if (isUrlSuffixStartChar(char)) {
// '/', '?', or '#'
stateMachine.state = State.Path;
} else if (isDomainLabelChar(char)) {
} else if (isDomainLabelChar(char) || hasDirectionalChar(char)) {
// Stay in the DomainLabelChar state
} else {
// Anything else, end the domain name
Expand Down
14 changes: 14 additions & 0 deletions src/parser/uri-utils.ts
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Expand Up @@ -110,6 +110,10 @@ export function isDomainLabelChar(char: string): boolean {
return char === '_' || isDomainLabelStartChar(char);
}

export function hasDirectionalChar(char: string) {
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@gregjacobs gregjacobs Sep 8, 2022 •
edited
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Minor, but can we rename this to isDirectionOverrideChar, and add a jsdoc comment above it explaining why it's used?

Can add a link for #377 too inside the jsdoc to point developers to the original issue that this new function solves

return /[\u202a-\u202e\u200e-\u200f]/g.test(char);
}

/**
* Determines if the character is a path character ("pchar") as defined by
* https://tools.ietf.org/html/rfc3986#appendix-A
Expand Down Expand Up @@ -168,6 +172,11 @@ export function isValidSchemeUrl(url: string): boolean {
return false;
}

// If url contains directional change character prevent it from linking
if (hasDirectionalChar(url)) {
return false;
}

const isAuthorityMatch = !!schemeMatch![1];
const host = schemeMatch![2];
if (isAuthorityMatch) {
Expand Down Expand Up @@ -213,6 +222,11 @@ export function isValidTldMatch(url: string): boolean {
return false;
}

// If url contains directional change character prevent it from linking
if (hasDirectionalChar(url)) {
return false;
}

const tld = hostLabels[hostLabels.length - 1];
if (!isKnownTld(tld)) {
return false;
Expand Down
7 changes: 7 additions & 0 deletions tests/autolinker-url.spec.ts
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Expand Up @@ -1032,6 +1032,13 @@ describe('Autolinker Url Matching >', () => {
});
});

describe('unicode exploits', () => {
fit('text with directional change characters should not be linked', () => {
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Careful: fit -> it

expect(autolinker.link('foo.com\u202Ebar.com')).toBe('foo.com\u202Ebar.com');
expect(autolinker.link('foo.com\u202Emoc.rab')).toBe('foo.com\u202Emoc.rab');
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In addition to the domain name tests here, we should add tests for when the \u202E char appears in the path, query string, and hash sections of the URL.

Also, can we add tests for each of the direction override chars like you had in #386?

});
});

function generateCombinationTests({
schemes,
hosts,
Expand Down