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Date: Wed, 17 Mar 2010 14:00:43 +0000
From: Brian Stafford <brian@...fford.uklinux.net>
To: Ludwig Nussel <ludwig.nussel@...e.de>
Cc: oss-security@...ts.openwall.com, libesmtp@...fford.uklinux.net,
security@...ntu.com, Pawel Salek <pawsa@...ochem.kth.se>,
jskarvad@...hat.com
Subject: Re: CVE Request: libesmtp does not check NULL bytes
in commonName
Ludwig Nussel wrote:
> Brian Stafford wrote:
>
>> Since both the original and patched versions of match_component()
>> implement wildcards rather less liberally than RFC 2818 implies, I
>> decided to move towards the approach in the I-D. match_component() now
>> accepts either a string or a single wildcard '*'. Matched characters
>> are validated against the set of valid domain name component characters
>> , that is, *.example.org will not match %.example.org, nor for that
>> matter will the pattern %.example.org. Question: should underline '_'
>> be in the set of valid characters?
>>
>
> AFAIK underlines are not allowed in DNS. I'm sure someone knows the
> RFC for that too :-)
>
They are permitted in some contexts but not in actual domain names, for
example a SRV record question to a name server contains stuff like
_smtp._tcp.host.example.org The host.example.org section is forbidden
from using _ but obviously the name server itself supports it so it can
handle the _smtp._tcp components. I am assuming that since we're
validating domain names and not name server queries, the _ is forbidden
but if anyone out there can clarify it might be useful :-)
> cu
> Ludwig
>
>
Brian
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