IPv6 and gemini

[solderpunk]

> >> Obviously 4 is my favourite because it's less (no) work for me. :)
> >
> >   I like 4 as well.
> 
> Yay!
>

I would like to hope that it won't be *too* much longer before 4 just
kind of happens because networking libraries will have gotten to the
point where you have to actively go out of your way to write IPv4-only
code.

Sorry that the Zaibatsu is doing a bad job of leading by example on
this front!  I was fully prepared to accept the blame for this, since
the gegobi server was thrown togeher over a few evenings and I just
didn't think about IPv6.  I thought I'd quickly patch it to support
serving on both IP versions at once before making this post, but...

...it turns out the quick and easy TCP server utilities in Python's
socketserver module are (still, in 2019 for crying out loud)
hard-coded to only work with IPv4.  So it's not a quick patch, but a
slightly larger project. :(   Maybe I was a bit optimistic in my first
paragraph.

Since starting the Gemini project, this is the second time I've felt
disappointed in Python's standard library, which is a rare thing.  At
gemini://mozz.us/journal/2019-08-21.txt, Michael writes about how the
ssl module can't accept a self-signed client certificate.  Even worse
than that, while it's possible to accept self-signed server
certificates, you can't get direct access to the details of that
certificate (like, say, the validity start and expiry dates).  With
CA-validated certificates you can easily get this data.  If the cert
is self-signed, you can only get an x509 encoded representation of the
cert - and there's nothing in the standard library to decode it!  The
ssl module really does seem to be designed to let people who don't
understand TLS very thoroughly write HTTPS stuff without shooting
themselves in the foot (the docs even talk explicitly about "Web
servers" instead of just "servers"!).  And, of course, I understand
why it's useful for a library with that kind of interface to exist.
But I *do* expect to be able to "go off-road" when I really want to.
This is going to make it a big pain to get a proper TOFU system in
AV-98, grumble, grumble.  When I eventually get around to writing my
own server, I'll definitely do it in something other than Python:
probably Go.

Any way, perhaps the most interesting thing to come out of this
conversation is the matter of using URLs with IP addresses instead of
hostnames as Gemini requests.  I'd guess a lot of existing servers
don't handle this well.  And, as mentioned, in the case of
hostname-based virtual servers, it's not entirely clear what handling
this well even means.  I wonder if it's worth explicitly disallowing
such requests?

-Solderpunk