[exim] Loopp through IP addresses in received header

Hi,

I'd like to loop through all of the IP addresses in the received headers
and check each one to see if that address is in a list of address
blocks, like 12.23.0.0/16 : 34.56.67.0/24 : 1.6.0.0/8

First can this be done in Exim 4.67? Or should I immediately look to a
stored procedure for help?

Thanks.
Craig