[spec] mercury highlights ☿️

[Petite Abeille]

BACKGROUND
Back in mid-2020, Solderpunk outlined the draft of a minimal subset of Gemini, named Mercury:

https://portal.mozz.us/gemini/gemini.circumlunar.space/users/solderpunk/gemlog/the-mercury-protocol.gmi <https://portal.mozz.us/gemini/gemini.circumlunar.space/users/solderpunk/gemlog/the-mercury-protocol.gmi>

That subset was always good enough for my needs, and that's what I have been using since ? instead of Gemini proper.

What follows is my implementation highlights of Mercury ? for the record.


SERVICE DISCOVERY
mercury:// IRIs SHOULD be resolved through DNS service discovery:

# dig +short TXT _mercury._tcp.host.xyz.
multiaddr=/dns/host.xyz/tcp/1958/tls/sni/host.xyz

multiaddr ?
User-agents MUST support tcp.
User-agents MAY support tls.

Default multiaddr /dns4/host.xyz/tcp/1958


REQUEST 4,096 bytes UTF-8 IRI line
mercury://host.xyz/


RESPONSE 4,096 bytes UTF-8 status line 
20 text/mercury;charset=utf-8;
Hello Mercury! ??

=> mercury://host.xyz/license CC0-1.0 
<end of connection> 


STATUS
2 digits code, 4,096 bytes UTF-8 

2x (SUCCESS) 4,096 bytes UTF-8 content-type status line
20[ text/mercury;charset=utf-8;]

3x (REDIRECT) 4,096 bytes UTF-8 IRI status line
30 mercury://host.xyz/

4x (FAILURE) 4,096 bytes UTF-8 status line
40[ DESCRIPTION]


TEXT/MERCURY
text/mercury;charset=utf-8;

Text lines
Any line which is not a link.

Link lines
=> IRI[ DESCRIPTION]

=> mercury://host.xyz/license CC0-1.0 


MERCURI URN
urn:mercury:capa

CAPA REQUEST
urn:mercury:capa

CAPA RESPONSE
20 text/mercury;charset=utf-8;
=> urn:mercury:capa
<end of connection> 

Servers MUST support urn:mercury:capa.


MINIMAL SERVER
# while true; do { echo -e '20\r\n=> urn:mercury:capa'; } | nc -l 127.0.0.1 1958; done

MINIMAL CLIENT
# echo -e 'urn:mercury:capa\r\n' | nc 127.0.0.1 1958
20
=> urn:mercury:capa


That's all folks.


?0?

? https://github.com/multiformats/multiaddr <https://github.com/multiformats/multiaddr>





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