if err != nil {
		err = &OpError{Op: "file", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return
}

// PacketConn is a generic packet-oriented network connection.
//
// Multiple goroutines may invoke methods on a PacketConn simultaneously.
type PacketConn interface {
	// ReadFrom reads a packet from the connection,
	// copying the payload into p. It returns the number of

// loopback IP address or local file system path.
//
// The provided network must be "udp", "udp4", "udp6" or "unixgram".
func NewLocalPacketListener(network string) (net.PacketConn, error) {
	stackOnce.Do(probeStack)
	switch network {
	case "udp":
		if canListenTCP4OnLoopback {
			if c, err := net.ListenPacket("udp4", "127.0.0.1:0"); err == nil {
				return c, nil
			}
		}