Trying to fetch SRV data with libunbound / libldns
Rick van Rein
rick at openfortress.nl
Thu May 12 13:51:36 UTC 2016
I'm trying to use libunbound (and possibly libldns) to pull out SRV
records. I am not certain how to proceed, based on the documentation
that I could found in the form of man pages, tutorials and doxygen.
Am I correct that libunbound returns RDATA unmodified, and is basically
concerned with the security chain but not the RDATA contents? And so,
that I have to turn to another tool?
I therefore looked at LDNS, but that does not seem to help either. I
don't mind following the RFC (though in the case of SRV it is not
explicit on the wire format) to pull out data, but I would be surprised
if I was to make assumptions about the structure of hosts, especially
because it may point back into a DNS packet. Is this really how it is
done though? Then, should I assume the data[i]/len[i] to be pointers
into the frame, and compute offsets manually?
I can hardly believe that this hasn't been tried before :) but as I
said, I can't find the documentation that answers this with clarity. So
any help is welcome, including pointers to documentation that I've
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