cname chaining with bind8 and 9

[Josh Littlefield]

I know this bug existed in BIND 4, and maybe it's still in BIND 8.  In general,
when BIND 4/8 recieves a reply from a some other nameserver, it retransmits
that reply on to the requesting client, replacing the request IDs.  In the case
where BIND has managed to chase some CNAMEs through cache before forwarding,
the request forwarded to the other nameserver is different from the request
sent by the client.  Yet, the response is still forwarded to the client, who
looks at it as sees the query section doesn't match the question originally
asked.  If the client drops the request and retransmits, it will likely get a
good reply becuase BIND has now cached the entire CNAME chain.

Christophe Deleuze wrote:

> Barry Margolin <barmar at genuity.net> writes:
>
> > I tried to reproduce your problem, but I ran into the following problem:
> > the world.activia-networks.com domain, which is part of your CNAME chain,
> > is delegated to a private address:
>
> Yes indeed.  This is from a testbed in a private network.  By the way, when
> I said bind8 it's more precisely bind8.2.2p5 (I haven't investigated on
> other 8.x versions).
>
> > Christophe Deleuze  <deleuze at ActiVia.net> wrote:
> > >If I use bind 8, this is what happens:
> > >
> > >bash# dig @bind8-dns www.francecast.com
> > >
> > >; <<>> DiG 8.2 <<>> @bind8-dns www.francecast.com
> > >; (1 server found)
> > >;; res options: init recurs defnam dnsrch
> > >;; wrong query name:
> > >;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
> > >;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
> > >;; QUERY SECTION:
> > >;;      cov-l.map.cannes.example.com, type = A, class = IN
>
> Anyway, this "wrong query name" seems a bit strange uh?
> The wrong query name is actually the target value of the first cname.
>
> --
> Dr. Christophe Deleuze          Christophe.Deleuze at ActiVia.net
> ActiVia Networks                http://www.activia.net

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Josh Littlefield                                  Cisco Systems, Inc.
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