Addrinfo#ipv6_mc_sitelocal?

static VALUE
addrinfo_ipv6_mc_sitelocal_p(VALUE self)
{
    struct in6_addr *addr = extract_in6_addr(self);
    if (addr && IN6_IS_ADDR_MC_SITELOCAL(addr)) return Qtrue;
    return Qfalse;
}