@philiprehberger/safe-regex

Validate and sanitize regular expressions to prevent ReDoS attacks.

Installation

npm install @philiprehberger/safe-regex

Usage

import { isSafe, safeParse, escape } from '@philiprehberger/safe-regex';

isSafe('abc');
// => true

isSafe('(a+)+');
// => false (nested quantifier — catastrophic backtracking)

const regex = safeParse('abc', 'i');
// => /abc/i

const unsafe = safeParse('(a+)+');
// => null

escape('hello.world');
// => "hello\\.world"

escape('a+b*c?');
// => "a\\+b\\*c\\?"

API

isSafe(input: string | RegExp): boolean

Check whether a regular expression is safe from ReDoS attacks. Detects nested quantifiers and overlapping alternations that cause catastrophic backtracking.

safeParse(str: string, flags?: string): RegExp | null

Compile a regex string into a RegExp only if it passes safety checks. Returns null if the pattern is unsafe or invalid.

escape(str: string): string

Escape all regex special characters in a string so it can be used as a literal match: . * + ? ^ $ { } ( ) | [ ] \

Development

npm install
npm run build
npm test

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License

MIT