Re: [exim] IPv6 address comparison, and callout vs VRFY

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Autor: Philip Hazel
Data:  
Para: David Woodhouse
CC: exim-users, Wouter Verhelst
Asunto: Re: [exim] IPv6 address comparison, and callout vs VRFY
On Thu, 18 Nov 2004, David Woodhouse wrote:

> You're right it probably ought to be canonicalised. I was going to
> suggest ${if match_host($sender_host_address}{2001:838...}{0}{1}}
> but match_host isn't actually implemented.
>
> The documentation has the comment "This is because hosts have two
> identities: a name and an IP address, and it is not clear how to specify
> cleanly how such a test would work. At least, I haven't come up with
> anything yet."
>
> Personally I'd be inclined to make match_host take a numeric IP address,
> canonicalise it and match it against a hostlist. I don't see where we'd
> want to use a _name_ as the item to match in a hostlist.


The point is that if I did that, it would be incompatible with host
lists as used elsewhere, where you can use either a name or an IP
address. It would be a huge gotcha.

I suppose we could make them separate:

${if match_host_address{...
${if match_host_name{...

Or, I suppose, Exim could look up the name if you wrote something like

${if match_host{$sender_host_address}{*.a.b.c:1.2.3.4}...

I just felt uncomfortable about this feature, which is why I haven't
done anything about it.

It is probably the case the implementing the funny mixed host lists that
currently exist was the real mistake. I should perhaps have invented two
different kinds of list from the start. But far too late to change that
now.

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.
Get the Exim 4 book:    http://www.uit.co.uk/exim-book