controlling responses to ANY queries

[Sam Trenholme]

> First off thank you for Mara. We're seeing a rash of issues with mail servers from Yahoo.com. They unable to send to our domain because of a bug in qmail that sends an ANY query before doing MX lookups.

Some historical background: It's not a bug.  It's a workaround for a
bug in ancient versions of BIND (The feature was added to Qmail in
1996 to work around a bug in versions of BIND earlier than 4.9.4) [1]

> Since they are unreliable- is it possible to control the ANY query response size in Mara?

Mara does try and control the ANY response size by removing the NS and
AR sections of the reply to an ANY query.  Unfortunately, Mara has a
bug where the corner case of having any ANY query that's larger than
512 bytes is not handled at all (not only does it not give a proper
truncated reply back, but also "zoneserver" does not appear to let
these packets through via DNS-over-TCP).

Unfortunately, my plate is pretty full and I don't know when I will
have time to fix Mara's handling of oversized ANY packets.  The only
fix in place right now is to remove records until the ANY query fits
in 512 bytes.

> Ps. Congrats on the new job!

I am very pleased to have it and I would not have it today if I did
not work on Mara for so many years.

- Sam

[1] http://homepages.tesco.net/J.deBoynePollard/Softwares/qmail/#any-to-cname