DNS headache

mraray · 01-01-2006, 11:14 PM

Hi EveryOne,

I have been looking around for dns lookup examples (blocking is fine) written in C.

I want to be able to look up records (ie mx) - so the gethostbyname functions are not suitable.

Can anyone point me to some simple examples? (I have been googling, but no luck)

Kind Regards,
Andrew.

paulsm4 · 01-02-2006, 12:16 AM

Hi -

There's no "low-level DNS API" that I'm aware of.

A modest suggestion: try getting the source for "nslookup" and seeing how much of it is applicable to your project.

Another alternative is a Google search. Keywords might include "DNS resolver netdb ..."

'Hope that helps ..

primo · 01-02-2006, 01:02 AM

See resolver(3).

There are plenty of alternative DNS libraries out there:
http://www.chiark.greenend.org.uk/~ian/adns/
ftp://athena-dist.mit.edu/pub/ATHENA/ares/
http://cr.yp.to/djbdns.html

There's a mini-tutorial on the low-level aspects of DNS itself (not a tutorial on the resolver library):
http://hxdef.czweb.org/knowhow/coding-dns.txt

mraray · 01-03-2006, 03:27 AM

Thanks

- All of those are handy.

Cheers,
Andrew