IPFOBJ_IPFITER
obj.ipfo_type = IPFOBJ_IPFITER;
error = ipf_inobj(softc, ptr, &obj, &it, IPFOBJ_IPFITER);
error = ipf_inobj(softc, data, &obj, &it, IPFOBJ_IPFITER);
error = ipf_outobj(softc, data, &it, IPFOBJ_IPFITER);