feat: special case CloudFlare client IP addrs

[vanodevium]

No description provided.

[mccutchen]

Thanks for the contribution, this makes sense to me. Left a couple of very nit-picky style change requests below, let me know if they make sense to you!

[codecov]

Codecov Report

Merging #148 (7686ee2) into main (8cd8f9c) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #148   +/-   ##
=======================================
  Coverage   98.04%   98.04%           
=======================================
  Files           8        8           
  Lines        1585     1588    +3     
=======================================
+ Hits         1554     1557    +3     
  Misses         22       22           
  Partials        9        9           

Files	Coverage Δ
httpbin/helpers.go	96.61% <100.00%> (+0.03%)	⬆️

[mccutchen]

Oh, also, please add a test case for this to the existing unit tests for getClientIP in helpers_test.go. (I expect our code coverage checks are gonna complain about this!)

[vanodevium]

I have done this request from web editor :) Ok.
Please wait when I could work from laptop.

Your nits are awesome!

[mccutchen]

👍 LGTM pending CI run

[vanodevium]

@mccutchen Please tell when this functionality would be in docker image?

[mccutchen]

Released in https://github.com/mccutchen/go-httpbin/releases/tag/v2.11.1. A docker image for that release will be pushed as soon as this workflow run finishes.

[mccutchen]

Docker image for v2.11.1 now available, and latest tag points to the same:
https://hub.docker.com/r/mccutchen/go-httpbin/tags