return "", err
	}
	path := f.Name()
	f.Close()
	os.Remove(path)
	return path, nil
}

// MulticastSource returns a unicast IP address on ifi when ifi is an
// IP multicast-capable network interface.
//
// The provided network must be "ip", "ip4" or "ip6".
func MulticastSource(network string, ifi *net.Interface) (net.IP, error) {
	switch network {
	case "ip", "ip4", "ip6":
	default: