Re: NS rr set from libdns

Thanks this is what I'm looking for. I just want a C program
to be able to say "tell me what you think the NS records are for this"
for a diagnostic tool and don't care how or what it has to do to
get the answer.

Like I would do with dig, if dig wern't so horribly broken.



At 08:30 PM 03/08/2009 +0200, Laurent Bercot wrote:
>> Hello;
>> I recently began using the libdns routines to make my C program to
>> DNS lookups. As advertised, it's fun! It's easy!
>
> Depending on what you're doing, you might be interested in skadns:
> http://www.skarnet.org/software/skadns/
>
> It's built upon DJB's libdns.
> The difference with using libdns directly is that with libdns, you
>have to include all of your DNS queries into your main loop, which
>might be impractical if said loop is already handling a lot of different
>sources of file descriptors. skadns hides the internal DNS stuff from
>you; it gives you one file descriptor to select on, and only triggers it
>on completed queries.
>
> Of course, it won't help you at all if you're interested in sending
>basic iterative queries more than in just getting the result of standard
>recursive queries. In other words, skadns allows you to perform several
>"dnsqr" simultaneously, but if you want to perform several "dnsq"
>simultaneously, you'll still have to do it by hand with libdns.
>
>
>> What would you do to get NS records with libdns?
>
> As Paul said, your best bet is to construct a packet by hand, taking
>inspiration from the internals of dns_ip4() and friends. You can have
>a look at how dnscache does.
>
> If using skadns, the right way to send a NS query for "example.com"
>would be something like:
>
> #include "dns.h"
> #include "skadns.h"
>
> ...
>
> char *domain = "example.com." ;
> char *q = 0 ;
> uint16 id ;
>
> ...
>
> if (!dns_domain_fromdot(q, domain, strlen(domain))) die() ;
> id = skadns_send(a, q, DNS_T_NS) ; /* a being your skadns stuff pointer */
>
>-- 
> Laurent
>
>