Avoid roundtrip to Text when inspecting x-forwarded-for header

[alexbiehl]

The TE.decodeUtf8 fails with an error on invalid encoding which is the cause for snoyberg/keter#312. http-reverse-proxy needs to be more careful when looking at user inputs and leave the rest to users.

[ulidtko]

Decent fix, LGTM

[jezen]

I'm not a maintainer of this repository, but I think the next steps are:

1. Bump the version in this package
2. Add an entry to the CHANGELOG
3. Merge
4. Upload to Hackage
5. Bump http-reverse-proxy dependency version in keter

@snoyberg Happy to help out here if you'll grant me the appropriate access rights.

[snoyberg]

Thanks @jezen, I've added you as a maintainer both here on GitHub and on Hackage.

[jezen]

I suspect CI is failing because the resolvers we're building against are now too old. I remember we saw this failure for MacOS builds elsewhere.

Here's the offending line: https://github.com/fpco/http-reverse-proxy/blob/master/.github/workflows/tests.yml#L17

Is it worth continuing to rely on stack for CI here instead of just cabal-install? Not sure… 🤔 Here's an example of what that change might look like: snoyberg/keter@20a33d9

@alexbiehl @ulidtko What do you think?

[alexbiehl]

Go for it. I prefer cabal these days as well. But don’t let that hold off merging this patch first — CIs that ran are all green.