ip_input_options
extern ipaddr_t ip_input_options(ipha_t *, ipaddr_t, mblk_t *,
dst = ip_input_options(ipha, dst, mp, ira, &error);
nexthop = ip_input_options(ipha, nexthop, mp, ira, &error);
dst = ip_input_options(ipha, dst, mp, ira, &error);