Win32::Resolv.get_dns_server_list

static VALUE
get_dns_server_list(VALUE self)
{
    FIXED_INFO *fixedinfo = NULL;
    ULONG buflen = 0;
    DWORD ret;
    VALUE buf, nameservers = Qnil;

    ret = GetNetworkParams(NULL, &buflen);
    if (ret != NO_ERROR && ret != ERROR_BUFFER_OVERFLOW) {
        w32error_raise(ret);
    }
    fixedinfo = ALLOCV(buf, buflen);
    ret = GetNetworkParams(fixedinfo, &buflen);
    if (ret == NO_ERROR) {
        const IP_ADDR_STRING *ipaddr = &fixedinfo->DnsServerList;
        nameservers = rb_ary_new();
        do {
            const char *s = ipaddr->IpAddress.String;
            if (!*s) continue;
            if (strcmp(s, "0.0.0.0") == 0) continue;
            rb_ary_push(nameservers, rb_str_new_cstr(s));
        } while ((ipaddr = ipaddr->Next) != NULL);
    }
    ALLOCV_END(buf);
    if (ret != NO_ERROR) w32error_raise(ret);

    return nameservers;
}