encap_attach_func
sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
const struct encaptab *encap_attach_func(int, int,
vifp->v_encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV4,
(void)encap_attach_func(AF_INET, -1, ipe4_encapcheck, &ipe4_encapsw,
(void)encap_attach_func(AF_INET6, -1, ipe4_encapcheck, &ipe4_encapsw6,