Re: [Exim] host lists and arbitrary host masks

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Author: Philip Hazel
Date:  
To: Marc Haber
CC: exim-users
Subject: Re: [Exim] host lists and arbitrary host masks
On Sat, 26 Feb 2000, Marc Haber wrote:

> Is there a reason why this is not natively supported by exim in the
> form I'd like to see?


You tell me how to implement it, and I'll think about it! :-)

Remember: DBM/cdb/NIS/etc files are keyed files. They are not scanned in
order.

> Maybe I am missing something, and I assume one
> would have to do up to 33 database lookups to verify if an address is


Exactly.

> listed in a host list that way, but even that seems more elegant than
> having 33 lookup entries in the host list itself.


> Maybe one could have a net<number-range>-<searchtype> entry like
> "net24-28-lsearch" if one knows that only /24, /25, /26, /27 and /28
> entries are in the database file?


That is just a shorthand for

net24-dbm;/file : net25-dbm/file : ....

It would still do 5 probes of the file for every address. (So for an
lsearch file it would read it 5 times.)


If, as you say, your list is never going to be more than a screen long,
then I would just use an interpolated file, and forget about using a
lookup. Then it really will just scan the list once. To be less
efficient than the multiple probes, I suspect the list would have to be
quite long.

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.