[ldns-users] how to check existence of EDNS in read packet

Bedrich Kosata bedrich.kosata at nic.cz
Mon Oct 25 13:40:51 UTC 2010


I have the following problem. When parsing DNS packets, I need to know 
if an OPT RR containing EDNS is present. However, it seems that ldns 
parses this RR separately and then removes it from the additional section.
What is the best way to find out if this RR was present in the original 
data? I need this to find out if the zero returned for edns version is a 
real value or a default one.
It seems that the best I can do for now is to use the value of 
_edns_udp_size, but this could be zero as well (at least in theory), 
could it not?

I would be glad for any insight.

Best regards


Bedrich Kosata
CZ.NIC Labs <http://labs.nic.cz>

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