On Mon, Apr 13, 2009 at 03:23:11PM -0700, Heath Morrison wrote:
[ Redirected from postfix-devel ]
> I noticed recently the addition of tcp lookup tables in postfix 2.6 so
> decided to play around with it a bit. I setup a little daemon that
> responds to the queries and everything seems to work nicely. I've been
> playing with using the tcp daemon for transport map lookups and came
> across something that seemed odd - lookups in my transport map daemon
> that originate from smtpd, including a lookup in response to "MAIL
> FROM".
>
> I traced it through the source and found it originating in smtpd's
> smtpd_check_addr function, which is innocently described as "sanity
> checks an email address and returns non-zero in case of badness".
> There are a number of other calls inside smtpd that result in
> resolve_clnt_query() calls, though. All of them ignore the results
> except for check for a flag check against RESOLVE_FLAG_FAIL or
> RESOLVE_FLAG_ERROR.
>
> It feels concerning to me that the transport_maps backend could be
> flooded with lookups from all the random smtp connections that a
> server receives.
>
> Is this a legitimate concern? Am I expecting too much out of transport_maps?
Postfix performs exactly the required lookups. Transport lookups happen
in multiple places for legitimate reasons. If your tcp table driver
cannot keep-up, replace it with something more efficient.
Overly close inspection of queries generated by Postfix is generally
counter-productive.
--
Viktor.
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