Date: Fri, 22 Sep 2000 12:02:25 +1100 From: Mark.Andrews@nominum.com To: dima@unixfreak.org Cc: Tim Zingelman <zingelman@fnal.gov>, stable@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: 'host' command with CNAMEs Message-ID: <200009220102.e8M12Pi51386@drugs.dv.isc.org> In-Reply-To: Your message of "Thu, 21 Sep 2000 17:14:56 PDT." <20000922001456.5BC6E1F27@static.unixfreak.org>
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BIND 4 and BIND 8 bugs can be reported to bind-bugs@isc.org.
BIND 9 bugs can be reported to bind9-bugs@isc.org.
Mark
P.S. don't bother submitting this as it will just land in my
mailbox.
>
> --ELM969581696-60857-0_
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> > > As I recall, Sean Kelly wrote:
> > > > I've got two machines here, one running 4.1-STABLE (from Aug 3) and a
> > > > 5.0-CURRENT (from Aug 10) and both of them show the same issue. When
> > > > you use the 'host' command to resolve a CNAME, it will show all the A
> > > > records twice:
> > > >
> > > > (7) smkelly@edgemaster:~$ host www.microsoft.com
> > > > www.microsoft.com is a nickname for microsoft.com
> > > > microsoft.com has address 207.46.130.45
> > > > microsoft.com has address 207.46.230.218
> > > > microsoft.com has address 207.46.230.219
> > > > microsoft.com has address 207.46.230.218
> > > > microsoft.com has address 207.46.230.219
> > > > microsoft.com has address 207.46.130.45
> >
> > It is more complicated than that... the bug only shows up if you specify
> > an alias name...
>
> You are both correct. In fact, it looks like you're stating the exact
> same thing.
>
> The obvious problem is that if 'host' is resolving a CNAME, there are
> two independant places which display the real address. My guess is
> that at some point, two independant developers decided to change the
> way 'host' deals with CNAMEs, but they put their code in different
> places. When they commited their code to the CVS repository, there
> were no conflicts, and the second one to commit failed to notice that
> a part of his code was already implemented.
>
> This bug was actually fixed in rev. 8.28 of host.c (BIND v8.2.1), but
> was resurrected in rev. 8.31 (BIND v8.2.2-REL). Since ISC doesn't
> release their CVS logs to the public, I can't find out why this was
> done (perhaps a developer commited something based on an earlier rev.,
> and didn't merge this change).
>
> If anybody wants it, I've made a patch to correct the problem (see
> attached). It applies against src/contrib/bind/bin/host/host.c of
> 5-CURRENT (although host.c is the same in RELENG_4, and it applies
> cleanly there). I heard somewhere that the contrib/ tree shouldn't
> contain local changes, but I'm unclear as to where local changes to
> contribited software go, so I made it against that. Once you've
> applied it, all you should have to do is `( cd /usr/src/usr.bin/host
> && make)`, although I haven't tested that approach. This should also
> apply cleanly to host.c of BIND 8.2.3-T5B, as that's what is in
> FreeBSD.
>
> Hope this helps
>
> --
> Dima Dorfman <dima@unixfreak.org>
> Finger dima@unixfreak.org for my public PGP key.
>
> "When in doubt, use brute force."
> -- Ken Thompson
>
> --ELM969581696-60857-0_
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> Index: host.c
> ===================================================================
> RCS file: /usr/cvs/FreeBSD/src/contrib/bind/bin/host/host.c,v
> retrieving revision 1.1.1.3
> diff -u -r1.1.1.3 host.c
> --- host.c 2000/05/26 07:17:07 1.1.1.3
> +++ host.c 2000/09/21 23:46:26
> @@ -696,8 +696,18 @@
> if (!hp->ad)
> if (verbose && isls == 0)
> printf("The following answer is not verified as authent
> ic by the server:\n");
> - while (--ancount >= 0 && cp && cp < eom)
> + while (--ancount >= 0 && cp && cp < eom) {
> cp = pr_rr(cp, answer->qb2, stdout, filter);
> + /*
> + * When we ask for address and there is a CNAME, it
> + * seems to return both the CNAME and the address.
> + * Since we trace down the CNAME chain ourselves, we
> + * don't really want to print the address at this
> + * point.
> + */
> + if (cname && ! verbose)
> + return (1);
> + }
> }
> if (!verbose)
> return (1);
>
> --ELM969581696-60857-0_--
>
>
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--
Mark Andrews, Nominum Inc.
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark.Andrews@nominum.com
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