Ethereal-dev: Re: [Ethereal-dev] [patch, capture] MDNS changes

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From: Brad Hards <bhards@xxxxxxxxxxxxxx>
Date: Mon, 2 Dec 2002 07:53:52 +1100
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On Mon, 2 Dec 2002 07:52, Guy Harris wrote:
> On Fri, Nov 29, 2002 at 10:29:42AM +1100, Brad Hards wrote:
> > 3. PTR records are used a lot, and I noted a redundant "ptr" label that
> > looked ugly and didn't provide any extra information.
>
> Why is that different from the "addr" label in the summary line for A
> records?  Presumably that's redundant as well, as A records have only an
> address in them, just as PTR records have only a name in them.  Perhaps
> other record types that have only one item should be cleaned up as well.
Err, because I stared at lots of PTR records, and not many A records? There is 
a subtle difference, because addr is a bit clearer than A, but ptr isn't much 
different to PTR, assuming that you don't know DNS by heart.

Also, a subtle bit of semantics. Traditionally PTR records are used for 
mapping IP to Name (the reverse name lookup). However DNS service discovery 
uses PTR records as a general mapping from one part of the address space to 
another. So the Question in a PTR query might not be 4.3.2.1.in-addr.arpa. It 
might be _ichat._tcp.local.

> > Can someone have a look at this, and commit it if OK?
>
> Done.
Thanks.

> > Future: LLMNR and DNS are probably going to diverge a bit. It may be
> > useful to split the DNS code into two dissectors, sharing some common
> > code.
>
> Probably a good idea.  Note that NBNS and DNS share some common code as
> well, given that NBNS was DNS-influenced but isn't the same as DNS.
This is the fundamental point - multicast DNS isn't DNS.

Brad
- -- 
http://linux.conf.au. 22-25Jan2003. Perth, Aust. I'm registered. Are you?
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