Add logging of real remote IP - in case of proxies

[dlvoy]

Extends logging to capture X-Forwarded-For header (in case of proxies)

Description

When server is used behind reverse proxy, reported remote_addr reflects internal interface and port, not client external IP. This PR adds additional real_remote_ip that is filled with contents of X-Forwarded-For

Motivation and Context

Main motivation is enable logs to be used with web statistics tools (like AWStats) that require IP addresses to be present in log files

How Has This Been Tested?

Tested by providing (or not) X-Forwarded-For header with Postman

[joseluisq]

Could you just provide some log output of how this looks like?

And please add a short description about this feature on https://sws.joseluisq.net/features/logging/ and under some new Log Real Remote IP subtitle. See logging.md page for more details.

[dlvoy]

I've added documentation and added parsing of header - while creating documentation i found articles regarding log poisoning and simply appending contents of header would pose security risk - so current implementation requires header to contain valid, parsable IP

sample call and log to test it:

curl --header "X-Forwarded-For: 203.0.113.195, 2001:db8:85a3:8d3:1319:8a2e:370:7348" http://0.0.0.0:8080

2022-05-23T22:24:50.519540Z  INFO static_web_server::handler: incoming request: method=GET uri=/ remote_addr=192.168.1.126:57625 real_remote_ip=203.0.113.195

[joseluisq]

Ready for the next release. Thanks 👍

[joseluisq]

Released on v2.12.0