lkml.org 
[lkml]   [2012]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] Define ENONAMESERVICE and ENAMEUNKNOWN to indicate name service errors
David Howells wrote:

Jim Rees <rees@umich.edu> wrote:

> Define ENAMEUNKNOWN to indicate "Network name unknown". This can be used to
> indicate, for example, that an attempt was made by dns_query() to make a query,
> but the name server (e.g. a DNS server) replied indicating that it had no
> matching records.
>
> Would this be the same as NXDOMAIN? That is, does it mean the name server
> couldn't find a record, or does it mean that the record doesn't exist?
Is there a way to tell the difference? Can you store a negative record in the
DNS? Or is it that the DNS has records for the name, just not records of the
type you're looking for (eg. NO_ADDRESS/NO_DATA from gethostbyname())?

It's an important distinction to the resolver if you want to avoid dns
hijacking. See rfc2308. There doesn't seem to be a way to tell the
difference from the gethostbyname call, which was designed before this was a
problem. The on-the-wire dns query protocol does make the distinction.
I suspect kernel dns clients won't need to know the difference, but I think
it's useful if we decide on and document the meaning of the error codes.
Maybe the answer is that ENAMEUNKNOWN means the same as a HOST_NOT_FOUND
from gethostbyname().


\
 
 \ /
  Last update: 2012-02-09 14:47    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site