Hi, I've commited a new module named 'ipops' which provides operations with IPv4 and IPv6:
http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=59403946...
The README describes the module functions:
http://git.sip-router.org/cgi-bin/gitweb.cgi?p=sip-router;a=blob;f=modules/i...
The module has no dependecies on other siprouter modules or external libraries, so if it's ok for you it could be enabled by default.
Cheers.