Re: [exim] Potential logic error in retry handling for IPv4+…

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Author: Philip Hazel
Date:  
To: Marc Haber
CC: exim-users
Subject: Re: [exim] Potential logic error in retry handling for IPv4+IPv6 hosts
On Fri, 30 Dec 2005, Marc Haber wrote:

> >> Exim will believe the information from the additional section, and try
> >> delivering there.
> >
> >Aarrgghh!! Yes, that does explain it. Thank you for tracking this one
> >down.
>
> Have you already decided on how to fix this in exim? As this is a bad
> bug, we'd need to backport the fix to exim 4.50 as well for inclusion
> in the next Debian point release. I'd greatly appreciate a patch.


It seems that the only sensible thing to do is to ignore the additional
section completely, and that is what I plan to do. I have not decided
whether to be more elaborate than that or not, but I suspect that it is
not worth doing anything. Busy systems should have "nearby" DNS servers
so that the additional queries will be cheap; for unbusy systems it
won't matter much.

I have not looked at the source, but the patch should be trivial; just
delete (or skip) the code that processes the additional section.

I do not expect to actually look at this for one or two or three weeks.
I have been on vacation over Christmas and New Year, and this week is a
short one in which I want to do documentation work. Thereafter I am
planning on a PCRE blitz, which will probably last most of January.

-- 
Philip Hazel            University of Cambridge Computing Service
Get the Exim 4 book:    http://www.uit.co.uk/exim-book