Add IPv6 support to portcheck service

[titer]

Fixes: #1

• Use getaddrinfo+AI_NUMERICHOST instead of the IPv4-only inet_addr
• Add small test for IPv4 and v6 port checks

[kelson42]

@ckerr Any chance you could review the PR @titer was kind enough to provide? If merged, I guess he could deploy it straight and that way this ~10 years old problem would be finally behind us!

[ckerr]

lgtm. Thanks @titer 💚

[ckerr]

@titer next question, how does deployment work? 😸

[titer]

@ckerr thanks for the review!
I'm adding a bit of documentation in #5 - you don't seem to have access yet but I can add your ssh key any time.
This change is now deployed and the IPv6 check works fine for me

[ckerr]

@titer TBH the fewer tertiary things I have to know about / care about / fix when they break, the better. 🙂

If it could just redeploy whenever something's merged to the repo that would be so much better than if a year from now I have to dig out my notes on how I deployed it back in March of '23

[kelson42]

@ckerr We could build automatically a container image here using Github actions and then we just need to find a way to trigger the recreation of the container?! Something like https://hub.docker.com/r/containrrr/watchtower/ might be a solution. This is at least the kind of approach I would choose.

[ckerr]

I just want it to work; however @titer wants to do is fine with me.

...though it is nice to see Eric again thanks to this portcheck feature, so maybe it's sometimes a Good Thing for something to break once in awhile 😸