chore(server): tighten TRUST_PROXY hop-count parsing to strict integer-only#224
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CryptoJones merged 1 commit intoMay 19, 2026
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The TRUST_PROXY=<hop count> branch was:
```js
} else if (trustProxy && !isNaN(parseInt(trustProxy, 10))) {
app.set('trust proxy', parseInt(trustProxy, 10));
}
```
`parseInt` is lenient — `parseInt('1abc', 10)` returns `1`. An
operator typo like `TRUST_PROXY=1abc` would silently set the hop
count to 1, partially honoring a malformed value instead of
falling back to the implicit Express default (no trust).
Switch to a strict `/^\d+$/` regex match. Now anything that isn't
the literal string `true` or a clean non-negative integer string
falls through to the default. Operator typos surface as
"X-Forwarded-For not trusted" — a missing-trust observation is
debuggable; a partial-trust silent acceptance is not.
Tightened the `trustProxy && !isNaN(...)` check to
`typeof trustProxy === 'string' && /^\d+$/.test(trustProxy)` for
the same reason (the `!isNaN(parseInt(undefined, 10))` short
circuit was already handled by the leading `trustProxy &&`, but
the explicit type guard is clearer about intent).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Closes #223.
Summary
parseIntis lenient —parseInt('1abc', 10)returns1. An operator typoTRUST_PROXY=1abcsilently set hops=1 instead of falling through to the no-trust default.Switch to a strict
/^\d+$/regex match. Invalid values now fall through; typos become observable.Test plan
npm run lintcleannpm test— 672 passed (no behavior change for valid values; tightened path for invalid ones)Proudly Made in Nebraska. Go Big Red! 🌽 https://xkcd.com/2347/