[onionmx] SRV and v3 onions

[ale]

On 19/12/2018 23:27, Daniel Kahn Gillmor wrote:
> On Wed 2018-12-19 22:33:16 +0200, John Paraskevopoulos wrote:
>> Hopefully I'm not reading an irrelevant postfix documentation snippet
>> (please correct me if I'm wrong), but reading here
>> http://www.postfix.org/tcp_table.5.html I see no way how postfix could
>> support mail rerouting using multiple routes as a suggestion from the
>> "tcp_table".
> 
> I don't think this is the relevant documentation -- tcp_table(5) is not
> "how do i open a TCP connection?", rather it is "how do i get
> postmap-style lookups done over a TCP connection?"  So yeah, i think
> this not the right docs to read :)
> 
> The issue might be more about dealing with the transport(5) mechanism.
> Certainly postfix knows how to deal with an MX lookup that returns
> multiple values and is capable of falling back between them.  That's
> standard SMTP behavior (indeed, SRV is intended as a generalization of
> the MX record).

Sure, Postfix knows how to deal with MX lookups returning multiple
results. But that's done (AFAIK) by the smtp(8) client, whereas
transport(5) only provides a (single) next-hop lookup. The tcp_table
trick approximates the behavior we need with its dynamic lookups, but
we're (ab)using a mechanism not meant for this purpose.

This is what I remember of the original assessment - this solution was
good enough for a proof-of-concept :) but of course I'd be happy to
discover that we missed something obvious.


--
ale