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Writing a gemini client in bash

5/22/2020

I thought I'd hop on the train of (to, I'm sure, the chagrin of solderpunk) Gemini-client-writers this Memorial Day weekend. I liked the idea of dylanarap's

birch IRC client

which is written completely in bash -- no external dependencies at all. I thought I could get away with that at first, but I soon found that TLS is pretty tricky to implement (or I didn't want to implement it anyway). I was stuck.

Lucky for me,

a toot by @julienxx

gave me the seed for bollux's functionality:

The tiniest #gemini client

echo gemini://konpeito.media/index-spicy.gmi | 
openssl s_client -crlf -ign_eof -quiet -connect konpeito.media:1965

With that, I was off to the races. I plunked that one-liner into a script and added a little bit of interactivity, and I had a very basic gemini client. I couldn't navigate to other links, or page content, but I could get stuff!

State of the art

For a little bit, I toyed with building my own pager in bash, printing the raw control characters to clear the screen, switch to the alt buffer, and so on. I could not wrap my head around the flow, though, so I decided to use less. It turns out that less was a great choice, because as I was reading around in the manpages I found that less is actually quite powerful! I was able to customize keybindings and use exit codes to communicate with the parent process. Now that I'm thinking about it, though, I could use the pipe command to bollux itself with an argument that will let it open links and what-not. But I'm getting ahead of myself.

So here's what happens when you open a link in bollux:

Challenges

I ran into a number of challenges while writing bollux. I was stuck on file descriptors for a while, trying to exec 3<>/dev/fd/0 and read and write from that, or read -u 4 to get user input, or many other things.. I don't remember them all. After a while, I figured out that I just had to stay on &0 and &1 (i.e., /dev/stdin and /dev/stdout) for the gemini content, and when I wanted to hold up the program for input from the user, just run `read </dev/tty`.

The other big problem came in when I tried to clean up the code by writing it from scratch (I know it's not efficient, but it's how I do things). For some reason, the read-handle pipeline was just. not. working. I worked at it for like, 4 hours, before finally re-re-writing it and fixing it somehow.

Meta-note on this section: I'm realizing that I don't really remember what challenges I faced while writing bollux, probably because they were so traumatizing I've blocked them out from my mind. Of course, that can cause its own problems, as I outline in the very next section.

Release! (and lessons learned)

Finally, I was finished. I packaged it up, put it up

online,

and told the world about it. Then I went to bed because I was tired.

This morning, I woke up to find that the repo wasn't posted. Apparently, sr.ht's projects won't display a repo that's private/unlisted, even if it's set to public after it's added to the project. But I was able to remove the repo and re-add it, so I thought it was all smooth sailing.

But then, I got to work. And I started reading the mailing list. And I checked the sourcehut project. And I started getting pinged on Mastodon ...

Bollux wasn't working for anyone!!!

I was panicked. I can't SSH anywhere or do anything at work, really, so I wasn't sure what the problem was. I finally signed in to Python Anywhere (which has bash shells that I use for light development when I'm supposed to be working), copy-and-pasted bollux, and tried to find the issue. Turns out, this is the offending code:

	ssl_cmd=(openssl s_client -crlf -quiet -connect "$server/$port")
-----------------------------------------------------------^ R I G H T. H E R E.

Yep, that's a slash. Not a colon, which is what it's supposed to be. Last night I was reading through the OpenSSL manpage and I thought it said you could use a slash instead of a colon to separate the port, for ease-of-use with IPv6. So I changed it to a slash because ... I thought it *looked* prettier.

I broke bollux because of a e s t h e t i c s that no one would ever even see. :'(

So I changed it in Python Anywhere and tried to run it, and it *seems* to work. The problem is that now the servers kick the request, I'm hoping because the system on PA is neutered in some way. I'm going to make the change when I get home and TEST it, of course, then reply in all the places people are seeing issues right now (which includes

geddit,

the cool new reddit-like in gemspace.

I'm definitely testing software before releasing it next time.