ONS registration for open group server base URLs

[jagerman]

Having worked on the open group server a bit recently, I've noticed that getting into an open group (especially on mobile!) is a fairly painful experience: to load one up on Android, for instance, requires either the significant pain of copying from my computer and getting that paste onto Android (either by some Android app that does that sort of thing, or by using a QR code generator).

This sucks.

I think it would be quite easy to support public group ONS registrations. A registration would look something like:

Name (hashed): 
    Name: oxen-io
    Type: Session Open Group Server
    Value: http://116.203.70.33:80|a03c383cf63c3c4efe67acc52112a6dd734b3a946b9545f488aaa93da7991238
    Owner: T6TqhbeNbdNUeSM4sKabnbhkgMVwiHuTGLeem2c3TZNdUPNnFKs6S5W7tXntfLfjTEfv9LdpHNLKfbvWBpp83GmM1cRxBakoo
    Last updated height: 580058
    Encrypted value: abcdef0123456789424242...

And then a Session user could join oxen-io/session, Session would resolve the oxen-io part and build the URL from the baseURL + '/' + roomname + '?public_key=' + pubkey

[jagerman]

Another advantage: it would allow for changing open group URLs or pubkeys. Currently if you have to change URLs (especially if using a bare IP) clients completely lose the open group. If there was an ONS record involved then Session could, on connect failure, notice that the ONS record has changed and update the internal address accordingly.

[ianmacd]

I assume these would be permanent registrations to avoid accidental lapses affecting large numbers of clients.