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fix(rtrim): remove regex to prevent ReDOS attack #1738

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Nov 1, 2021
Merged

fix(rtrim): remove regex to prevent ReDOS attack #1738

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15 changes: 12 additions & 3 deletions src/lib/rtrim.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,16 @@ import assertString from './util/assertString';

export default function rtrim(str, chars) {
assertString(str);
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#Escaping
const pattern = chars ? new RegExp(`[${chars.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')}]+$`, 'g') : /(\s)+$/g;
return str.replace(pattern, '');
if (chars) {
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#Escaping
const pattern = new RegExp(`[${chars.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')}]+$`, 'g');
return str.replace(pattern, '');
}
// Use a faster and more safe than regex trim method https://blog.stevenlevithan.com/archives/faster-trim-javascript
let strIndex = str.length - 1;
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I am wondering why this is not in the else statement, but I might less understand that because we have done return already.

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It's exactly that. If an if block contains a return statement, the else block is unnecessary and the instructions after the block will only be executed when the if condition is not met!

while (/\s/.test(str.charAt(strIndex))) {
strIndex -= 1;
}

return str.slice(0, strIndex + 1);
}