Initially, I wanted to call this post “a game of 0 lines of HTML, JS, and CSS,” inspired by this post , but that would be too loud. Anyway, greatly degrading the UX, I got tic-tac-toe, working exclusively with the power of the DNS protocol.







For an unprepared user it looks, of course, scary, but even the browser is not needed for the game.



In order to enter the game, you need to execute the following command, which involves accessing my dns-server:

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$ dig @ns.f1remoon.com game.f1remoon.com. TXT 

I also made a small help, which is available in TXT records for the domain help.game.f1remoon.com :

How it works?

At first I tried to just configure bind9 correctly, but I was very upset: the order of issuing TXT records was random. This, of course, brought some exoticism into the game, but was absolutely unacceptable. I had to drop the idea and look in the direction of a samopisny DNS server. Armed with the desire to learn something new, I took the golang and the Go DNS library and it turned out to be a simple server, not much different from the examples.



The next difficulty was all the combinations of the game. There is a big thanks to Sirion : I took its html-files and translated it in a format that suits me.



Since the dig command, unlike the browser, does not store the url and does not allow poking across the field, you will have to leave it to the user. For the game, the field was marked as numpad:

 7 8 9 4 5 6 1 2 3 

When requesting a move, you should always give the full history of moves in reverse, for example, the command for the third move in the cell “9” will look like this:

 $ dig @ns.f1remoon.com 9.4.5.game.f1remoon.com. TXT 

Repository with code: github.com/Firemoon777/tic-tac-toe-dns



UPD: Prototik suggests using the more convenient to play option with the key + short:

 $ dig +short TXT @ns.f1remoon.com 9.4.5.game.f1remoon.com. "o" "_" "x" "x" "x" "o" "o" "_" "_"