[onionmx] SRV and v3 onions

[ale]

On 12/19/18 11:34 AM, meskio via onionmx wrote:
> I agree v3 records should be prioritized in an attempt to face v2 out.
> 
> Having a fast look into the code into the existing implementations[0][1] it 
> looks like none of them acknowledges the priorities. The go implementation only 
> uses the first found, the python interpretation looks like it might try all of 
> the ones found.
> 
> I think adding a second record might break existing setups.

Well AFAIK the Go implementation has zero users, so I wouldn't be too
concerned about breaking changes on that front :)

Unfortunately (and I hope I'm remembering correctly the state of
things), there's a deeper issue with the semantics of supporting
multiple SRV records and priorities: the current Postfix implementations
(both of them) aren't hooked at the right "level" to handle retries,
there is no tracking of previous delivery state, so we can't handle
priorities in the same way as you would with MX records. Not a big deal
if all you want to use SRV priorities for is v2/v3 selection, but worth
keeping in mind.


--
ale