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Message-ID: <20140904221551.GH10361@port70.net>
Date: Fri, 5 Sep 2014 00:15:52 +0200
From: Szabolcs Nagy <nsz@...t70.net>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] fix handling of zero length domain names in
dn_expand
* Rich Felker <dalias@...c.org> [2014-09-04 16:20:53 -0400]:
> > char *dend = dest + (space > 254 ? 254 : space);
> > - int len = -1, i, j;
> > - if (p==end || !*p) return -1;
> > + int len = -1, i, j, first = 1;
> > + if (p==end || dest==dend) return -1;
>
> Note that this does nothing to handle negative space, whereas ncopa's
i assumed it to be ub
> such. Semantically it seems to be a zero-length component at the end
> (corresponding to "example.com.." rather than "example.com.", in the
> notation where final dots are not elided). Understanding whether it's
> legal or not probably requires some language-lawyering with RFC 1035,
the rfc is not very clear but i think this case should work
a name is a sequence of labels terminated by a 0 length label
a compressed name is a leading sequence of labels terminated
by a pointer that can be expanded to a name
if 'sequence of labels' can be empty and the conversion to
dotted string notation is done after concatenating the
leading and trailing sequence then there is no '..' issue
> - char *dend = dest + (space > 254 ? 254 : space);
> + char *dend;
> int len = -1, i, j;
> - if (p==end || !*p) return -1;
> + if (p==end || size <= 0) return -1;
> + dend = dest + (space > 254 ? 254 : space);
ok this part is better than mine
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