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⬅️ Previous capture (2023-01-29)

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CGI with Vger

Update 2022-02-02: added tic-tac-toe.cgi; see below

I have been running vger on my OpenBSD server for a while and am pretty happy with it. It is written by OpenBSD developer solene@ and has the right combination of small codebase and use of security mitigations like unveil(2).

https://tildegit.org/solene/vger

Last week, I came across a capsule that features a "like button" on its pages:

gemini://fixato.org/

This got me curious about CGI with gemini. After asking on tilde.chat #gemini IRC, tomasino gave me some hints, including from his video on the topic:

https://www.youtube.com/watch?v=9Anh0sNUCY4

First I thought I would need a different gemini server to do that, but then I saw that vger supports CGI via the `-c` flag. I created a directory `cgi-bin` and passed it to vger in inetd.conf which now looks like this:

127.0.0.1:11965	stream	tcp	nowait	gemini_user	/usr/local/bin/vger	vger -i -v -d /var/gemini/ -c /var/gemini/thfr.info/cgi-bin

I started with my first hello-world script, based on what I had previously made for HTTP CGI. I quickly realized that instead of "Content-type text/plain" I had to send "20 text/gemini" as the header, followed by CRLF (20 indicates success in gemini specification).

That worked, so I set out to make 2 other, more interactive CGI examples. Here is a list of the (fairly simple) early CGI applications:

Hello World

Persistent Counter

Popcat clone (missing counter and statistics)

Tic-Tac-Toe

Popcat is based on:

https://popcat.click

And here the links to view or download the source code of these 3 examples:

/cgi-source/testcgi.cgi

/cgi-source/testcounter.cgi

/cgi-source/popcat.cgi

/cgi-source/tic-tac-toe.cgi

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