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Article: 1845
From: Anthony Howe
Date: 2008-03-15 07:55:12 -0400
Subject: Re: [SPAM] milter-spiff returning DNS UDP response truncated,

Removal...........: milters-request@milter.info?subject=remove
More information..: http://www.milter.info/#Support
--------------------------------------------------------

Michael Grant uttered...:
> Milter: to=<user@example.com>, reject=451 4.4.3 sender
> <someone@accenture.com> via 170.252.72.96 SPF result TempError: DNS
> UDP response truncated, TCP support not implemented

> Second, I don't know why this domain is returning a truncate bit on
> this dns query.  If I do it by hand with dig, it works fine.

Did you follow the chain of nested include: entries?

> My understanding of DNS is that the udp query could truncate if the
> response is greater than 512 octets.  Is milter-spiff building a dns
> query that's sometimes returning data greater than this limit?

No. It is not in the building of the query, it is in the response(s) 
returned.

I've already written a new asynchronous DNS client API, Posted Domain 
Query (pdq), which does handle TCP based queries and multihomed MX and 
PTR records much much better. At some point I have to port all the 
milters that use my older Dns API to use pdq: milter-spiff, 
milter-sender, and milter-link come to mind. Part of the delay is I want 
to debug pdq more before I use it all my code, but really the best way 
to test it is just get it out there. Maybe milter-spiff would be a good 
place to start.

-- 
Anthony C Howe        Twitter: SirWumpus                    SnertSoft
+33 6 11 89 73 78       Skype: SirWumpus        BarricadeMX & Milters
http://www.snert.com/     ICQ: 7116561
     http://www.snertsoft.com/

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