VF-1, AV-98 and Agena
---------------------

This post is mostly a response to Tomasino's
public daydreaming about seamless browsing of
Gopherspace and Geminispace with the one
client[1].  But it's also a little bit of an
update about various software projects of
mine.

First of all, a bit about my VF-1 gopher
client: there hasn't been a formal release
since July, but there *has* been quite a bit
of sporadic development in the Git repo since
then.  I have been promising various people
that 1.0.0 is "just around the corner" for
quite a few months now and I really do mean
it!  The real hold up is writing good and
complete documentation, which I really just
need to push through and do.  Code-wise, I
think we are good to go, but what I'd like to
do is ask interested people to please
consider cloning the repo at
https://github.com/solderpunk/VF-1.git and
surfing Gopherspace with the development
version for a while.  If anything breaks or
otherwise seems wrong, please let me know!

Lots of the development work has been tidying
the code up, removing unecessary duplication,
etc., but there is some exciting new stuff
visible to the end-user that you should play
with if possible:

* Maybe most importantly, VF-1 will now
  connect to servers via IPv6 if they have an
  AAAA record and the server is listening on
  IPv6.  If there's nothing listening on
  IPv6, or you don't have an IPv6 connection
  or your system doesn't even have IPv6
  support enabled, it will automatically fall
  back to IPv4.  In my experience this
  doesn't result in any annoying slow timeout
  problems like IPv6 often did in the old
  days, but it would be reassuring to hear
  from more people that this still works
  nicely.  If this does cause you problems or
  you have an irrational hatred of IPv6 you
  can put `set ipv6 false` in your RC file
  and VF-1 won't ever even try to use it.
* Content handlers can now be shell
  pipelines, so you should now be able to
  Make VF-1 Sexy[2] Tomasino-style without
  having to resort to writing little helper
  scripts.
* There's now a debug mode, which you you can
  turn on from the prompt with `set debug
  true` or when starting VF-1 with `--debug`.
  This will print various bits of info, in
  ANSI-escape-coded green text, as VF-1 does
  things so you can see when VF-1 is trying
  to use IPv4 or IPv6, what kind of MIME type
  it's inferring for content, etc.  Probably
  not much use for normal people, but it was
  handy for me when adding the IPv6 stuff.
* If debug doesn't satisfy your desire to
  peek under the hood enough, there's also
  now a (largely gratuitious, I admit)
  blackbox flight recorder you can access
  with the `blackbox` (or `bb`) command which
  will tell you how long VF-1 has been
  running for and, in that time, how many
  requests you've sent, how many unique IPv4
  and IPv6 hosts you've hit, how many bytes
  you've downloaded, how many of each
  different item type you've visisted, how
  many errors of various kinds you've
  encountered, etc.  Again, mostly written
  to aid me as a developer and not too
  interesting to normal users.

Okay, that's it for VF-1.  Now, onto AV-98.

I guess some readers may be in the dark about
AV-98 if they didn't start following my
Gemini posts[3] after I promised[4] to stop
spamming my own phlog with lunatic rants
about new internet protocols.  To update
quickly, Gemini has certainly become "a
thing" and there are now about 10 public
servers running the protocol, whose core has
more-or-less solidified, modulo a
long-running and surprisingly complicated
discussion about how to handle text wrapping.
There are multiple server and client
implementations appearing from multiple
authors.  On the client side, I have written
a Gemini client derived from VF-1, and in my
own grand tradition of giving nice software
terrible names referencing vintage anime I
called it AV-98[5].  It's how I surf
Geminispace.  It has precisely the same look
and feel as VF-1.  As the TLS-handling
becomes a bit more sophisticated this may
stop being true, but after the initial
Gopher-to-Gemini conversion, it turned out
that I had to *remove* more code than I had
to add, in order to offer more or less
exactly the same user experience.  I took
this as a sign that the design decisions made
for Gemini were all more or less Good Things
and am pretty happy about it!

Right, responding at last to poor Tomasino,
if he's still awake.  Tomasino pondered:

> I was thinking on AV-98 and VF-1 and how
> they're so wonderfully similar. It would be
> so neat to have a single client that could
> browse gopher & gemini protocols seemlessly

I've certainly had the same thought!  In the
earliest days I was worried that this was
going to mean maintaining three separate
programs which sounded like No Fun, but
happily it turns out that, IMHO, this is no
longer necessary after I wrote another piece
of software, called Agena[6].

One way that Gemini differs from Gopher is
that, whereas Gopher clients only send a
"selector" to servers as part of their
request (Gopher selectors are roughly
equivalent to the path component of a HTTP
URL), Gemini clients send a full-blown URL
including the protocol and hostname (although
you can leave the protocol out and it will,
naturally enough, default to gemini://).  The
main motivation for this was to permit
hostname-based virtual hosting, but it also
allows proxy servers - even
protocol-translating proxy servers!  And
Agena is just such a thing, namely a
Gopher-to-Gemini proxy.

When you use AV-98 to follow a link to a
resource hosted via Gopher, it will try to
connect to a Gemini server running on
localhost (although you can use `set
gopher_proxy` to try anywhere else instead,
and more or on that later), and will send it
a request for the Gopher resource.  If you
have Agena running, it will request that
gopher resource and then send it back to
AV-98 as a Gemini response.  If the Gopher
resource is a menu, it will be translated
into a Geminimap.  Agena is aware of the h
itemtype URL: hack, and will transform any
such items in a Gopher menu into ordinary
links.  If the Gopher resource is not a menu,
Agena will try to figure out a MIME type for
it, in much the same way as VF-1 does, as
this is required in the Gemini response
header.

Since I've also been hacking on VF-1 I
haven't done it for a while, but after I
first wrote Agena for about a week or so I
surfed Gopherspace from home exclusively
using the AV-98-Agena combo and it worked
very, very nicely indeed.  I'd even call it
seamless.  And the great thing is that any
Gemini client can easily add support for a
Gopher proxy and then use Agena.  The
Gopher-to-Gemini translation logic only needs
to be improved and maintained in one project,
and nobody ever needs to bother to write a
client which *actually* speaks both protocols
(of course, if you really want to, I won't
try to stop you!).  This is a really
beautiful arrangement, IMHO.

But Tomasino goes on to note:

> Oh, it would be terrible to start your
> journey thinking you're on Gemini and
> safely using TLS only to move into Gopher
> without realizing it and be unprotected

Good point!  And I like some of Tomasino's
ideas about using symbols or colours to
indicate which protocol a link is over.  But
here's another thought: when you are running
Agena locally, the fact that Gemini mandates
TLS doesn't do you much good, because you're
only securing a connection over your loopback
interface, and the Gopher request goes out in
the plain so your ISP can log and analyse the
response (well, unless you're some kind of
non-VPN-using werido).  But there's no reason
that your Gopher proxy has to be local!  Some
brave soul could run a public Agena instance,
and AV-98 users could browser Gopherspace
through it.  Then your ISP wouldn't be able
to view the content, and the original Gopher
host wouldn't learn who you were, either!
The person running the Agena instance, of
course, would know everything, although
because Gemini very deliberately doesn't have
anything analogous to cookies or superfluous
request headers which can be fingerprinted,
the admin of the public proxy has quite
limited ability to track your Gopher browsing
habits over time.

This solution isn't perfect, of course, it
would also slow Gopher browsing down a little
bit.  But it's an interesting idea that's
possible with extant software.  I need
another project like I need a hole in the
head right now, but if somebody *else* wanted
to set such a public proxy up, I'd help
spread the word.

[1] gopher://gopher.black:70/1/phlog/20190918-av-98-and-vf-1-daydream
[2] gopher://gopher.black:70/1/phlog/20190806-making-vf-1-sexy
Gopher-Gemini 
[3] gopher://zaibatsu.circumlunar.space:70/1/~solderpunk/gemini
[4] gopher://zaibatsu.circumlunar.space:70/0/~solderpunk/phlog/project-gemini.txt
[5] https://tildegit.org/solderpunk/AV-98
[6] gopher://zaibatsu.circumlunar.space:70/0/~solderpunk/gemini/announcing-agena-a-gemini-to-gopher-proxy.txt