PF_XROUTE
rp->rcb_proto.sp_family = PF_XROUTE;
.ri_dst = { .sa_len = 2, .sa_family = PF_XROUTE, },
.ri_src = { .sa_len = 2, .sa_family = PF_XROUTE, },
struct sockproto proto = { .sp_family = PF_XROUTE, };
.dom_family = PF_XROUTE,
struct sockproto proto = { .sp_family = PF_XROUTE, };