On 2016-10-17, Mike Tubby <mike@???> wrote:
>
> Couldn't we have - per perhaps shouldn't we have - a "safe domain name"
> function in Exim that could be used for this and elsewhere where an
> untrusted domain name enters - it would:
>
> * remove white space (tab, space, etc)
> * remove non-printing chars
> * remove 'quoting' and 'escaping'
> * make it lower case
> * only allow valid characters for a FQDN
why remove? why not just reject if it contains any badness?
> call it something like "safe_fqdn" and then you could do:
>
> ${if
> exists{/etc/mail/ssl/${safe_fqdn:tls_sni}.pem}{/etc/mail/ssl/${safe_fqdn:tls_sni}.pem}{/etc/mail/default-cert.pem}
>
> aren't computers are supposed to be doing the work for us...?
>
This:
${domain:a@$tls_sni}
will give the domain part if the $tls_sni is syntactically correct for a
domain name else it will give the empty string.
Is that not good enough?
${if exists{/etc/mail/ssl/${domain:a@$tls_sni}.pem}\
{/etc/mail/ssl/${domain:a@$tls_sni}.pem}\
{/etc/mail/default-cert.pem}\
}
it's going to try to use a file called /etc/mail/ssl/.pem if the sni
is empty or contains garbage, probably not a problem.
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