func newLookupPort(network, service string) (int, error) {
        acquireThread()
        defer releaseThread()
        var stype int32
        switch network {
        case "tcp4", "tcp6":
                stype = syscall.SOCK_STREAM
        case "udp4", "udp6":
                stype = syscall.SOCK_DGRAM
        }
        hints := syscall.AddrinfoW{
                Family:   syscall.AF_UNSPEC,
                Socktype: stype,
                Protocol: syscall.IPPROTO_IP,
        }
        var result *syscall.AddrinfoW
        e := syscall.GetAddrInfoW(nil, syscall.StringToUTF16Ptr(service), &hints, &result)
        if e != nil {
                return 0, &DNSError{Err: os.NewSyscallError("getaddrinfow", e).Error(), Name: network + "/" + service}
        }
        defer syscall.FreeAddrInfoW(result)
        if result == nil {
                return 0, &DNSError{Err: syscall.EINVAL.Error(), Name: network + "/" + service}
        }
        addr := unsafe.Pointer(result.Addr)
        switch result.Family {
        case syscall.AF_INET:
                a := (*syscall.RawSockaddrInet4)(addr)
                return int(syscall.Ntohs(a.Port)), nil
        case syscall.AF_INET6:
                a := (*syscall.RawSockaddrInet6)(addr)
                return int(syscall.Ntohs(a.Port)), nil
        }
        return 0, &DNSError{Err: syscall.EINVAL.Error(), Name: network + "/" + service}
}