lifr_subnet
if (lifr.lifr_subnet.ss_family == AF_INET6) {
sin6 = (struct sockaddr_in6 *)&lifr.lifr_subnet;
sin = (struct sockaddr_in *)&lifr.lifr_subnet;
if (lifr.lifr_subnet.ss_family != AF_INET6) {
sin6 = (struct sockaddr_in6 *)&lifr.lifr_subnet;
&lifr.lifr_subnet)->sin6_addr;