IDN with Gemini?

[Stephane Bortzmeyer]

On Tue, Dec 08, 2020 at 05:20:38PM -0500,
 Sean Conner <sean at conman.org> wrote 
 a message of 29 lines which said:

>   I was also surprised that UTF-8 characters *are* possible in DNS packets
> [2].

It is possible from the beginning, and it has been explicitely said in
RFC 2181, twenty-three years ago. "any binary string whatever can be
used as the label of any resource record".

gemini://gemini.bortzmeyer.org/rfc-mirror/rfc2181.txt

> I was, however, a bit disappointed that "gémeaux.bortzmeyer.org" and
> "xn--gmeaux-bva.bortzmeyer.org" didn't exist.

Then it means your DNS resolver is broken because
xn--gmeaux-bva.bortzmeyer.org (the A-label, the Punycode form) is in
the DNS.

% dig AAAA +noidnout xn--gmeaux-bva.bortzmeyer.org  

; <<>> DiG 9.11.5-P4-5.1+deb10u2-Debian <<>> AAAA +noidnout xn--gmeaux-bva.bortzmeyer.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18694
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 4, AUTHORITY: 7, ADDITIONAL: 7

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
;; QUESTION SECTION:
;xn--gmeaux-bva.bortzmeyer.org. IN AAAA

;; ANSWER SECTION:
xn--gmeaux-bva.bortzmeyer.org. 86400 IN	CNAME radia.bortzmeyer.org.
xn--gmeaux-bva.bortzmeyer.org. 86400 IN	RRSIG CNAME 8 3 86400 (
				20201218215750 20201204120249 10731 bortzmeyer.org.
				gKtCZZKsjTLdFsSKYtgvz1S+pRkZbxweG+6XOxVhJgYG
				gRzfWB8lhjSPaQ6BNK6YyGQreonObF1R43MDY5oQ66ti
				hNOfPp3/gz4wm5eAy3uzFi7xiwclshsLd0yZEaOPsTo6
				fYKfRp5XCG/yZOg85YdZxJB9LK9q+RIyOycGmI0= )
radia.bortzmeyer.org.	86400 IN AAAA 2001:41d0:302:2200::180
...