func (p *processor) getFlow(pkt gopacket.Packet) gopacket.Flow {
	mu := moldudp64Layer(pkt)
	//p.flowBufSrc.Reset()
	//p.flowBufSrc.Write(pkt.NetworkLayer().NetworkFlow().Src().Raw())
	//p.flowBufSrc.Write(pkt.TransportLayer().TransportFlow().Src().Raw())
	//p.flowBufSrc.Write(mu.Flow().Src().Raw())
	p.flowBufDst.Reset()
	p.flowBufDst.Write(pkt.NetworkLayer().NetworkFlow().Dst().Raw())
	p.flowBufDst.Write(pkt.TransportLayer().TransportFlow().Dst().Raw())
	p.flowBufDst.Write(mu.Flow().Dst().Raw())
	return gopacket.NewFlow(packet.EndpointCombinedSession, p.flowBufSrc.Bytes(), p.flowBufDst.Bytes())
}

func (t *TCP) TransportFlow() gopacket.Flow {
	return gopacket.NewFlow(EndpointTCPPort, t.sPort, t.dPort)
}

func (i *IPv4) NetworkFlow() gopacket.Flow {
	return gopacket.NewFlow(EndpointIPv4, i.SrcIP, i.DstIP)
}

// PPP is the layer for PPP encapsulation headers.
type PPP struct {
	BaseLayer
	PPPType PPPType
}

// PPPEndpoint is a singleton endpoint for PPP.  Since there is no actual
// addressing for the two ends of a PPP connection, we use a singleton value
// named 'point' for each endpoint.
var PPPEndpoint = gopacket.NewEndpoint(EndpointPPP, nil)

// PPPFlow is a singleton flow for PPP.  Since there is no actual addressing for
// the two ends of a PPP connection, we use a singleton value to represent the
// flow for all PPP connections.
var PPPFlow = gopacket.NewFlow(EndpointPPP, nil, nil)

// LayerType returns LayerTypePPP
func (p *PPP) LayerType() gopacket.LayerType { return LayerTypePPP }

// LinkFlow returns PPPFlow.
func (p *PPP) LinkFlow() gopacket.Flow { return PPPFlow }

func decodePPP(data []byte, p gopacket.PacketBuilder) error {
	ppp := &PPP{}
	if data[0]&0x1 == 0 {
		if data[1]&0x1 == 0 {
			return errors.New("PPP has invalid type")
		}
		ppp.PPPType = PPPType(binary.BigEndian.Uint16(data[:2]))
		ppp.Contents = data[:2]

func (u *UDP) TransportFlow() gopacket.Flow {
	return gopacket.NewFlow(EndpointUDPPort, u.sPort, u.dPort)
}

// TransportFlow returns a flow based on the source and destination SCTP port.
func (s *SCTP) TransportFlow() gopacket.Flow {
	return gopacket.NewFlow(EndpointSCTPPort, s.sPort, s.dPort)
}

// scan scans the dst IP address of this scanner.
func (s *scanner) scan() error {
	// First off, get the MAC address we should be sending packets to.
	hwaddr, err := s.getHwAddr()
	if err != nil {
		return err
	}
	// Construct all the network layers we need.
	eth := layers.Ethernet{
		SrcMAC:       s.iface.HardwareAddr,
		DstMAC:       hwaddr,
		EthernetType: layers.EthernetTypeIPv4,
	}
	ip4 := layers.IPv4{
		SrcIP:    s.src,
		DstIP:    s.dst,
		Version:  4,
		TTL:      64,
		Protocol: layers.IPProtocolTCP,
	}
	tcp := layers.TCP{
		SrcPort: 54321,
		DstPort: 0, // will be incremented during the scan
		SYN:     true,
	}
	tcp.SetNetworkLayerForChecksum(&ip4)

	// Create the flow we expect returning packets to have, so we can check
	// against it and discard useless packets.
	ipFlow := gopacket.NewFlow(layers.EndpointIPv4, s.dst, s.src)
	start := time.Now()
	for {
		// Send one packet per loop iteration until we've sent packets
		// to all of ports [1, 65535].
		if tcp.DstPort < 65535 {
			start = time.Now()
			tcp.DstPort++
			if err := s.send(&eth, &ip4, &tcp); err != nil {
				log.Printf("error sending to port %v: %v", tcp.DstPort, err)
			}
		}
		// Time out 5 seconds after the last packet we sent.
		if time.Since(start) > time.Second*5 {
			log.Printf("timed out for %v, assuming we've seen all we can", s.dst)
			return nil
		}

		// Read in the next packet.
		data, _, err := s.handle.ReadPacketData()
		if err == pcap.NextErrorTimeoutExpired {
			continue
		} else if err != nil {
			log.Printf("error reading packet: %v", err)
			continue
		}

		// Parse the packet.  We'd use DecodingLayerParser here if we
		// wanted to be really fast.
		packet := gopacket.NewPacket(data, layers.LayerTypeEthernet, gopacket.NoCopy)

		// Find the packets we care about, and print out logging
		// information about them.  All others are ignored.
		if net := packet.NetworkLayer(); net == nil {
			// log.Printf("packet has no network layer")
		} else if net.NetworkFlow() != ipFlow {
			// log.Printf("packet does not match our ip src/dst")
		} else if tcpLayer := packet.Layer(layers.LayerTypeTCP); tcpLayer == nil {
			// log.Printf("packet has not tcp layer")
		} else if tcp, ok := tcpLayer.(*layers.TCP); !ok {
			// We panic here because this is guaranteed to never
			// happen.
			panic("tcp layer is not tcp layer :-/")
		} else if tcp.DstPort != 54321 {
			// log.Printf("dst port %v does not match", tcp.DstPort)
		} else if tcp.RST {
			log.Printf("  port %v closed", tcp.SrcPort)
		} else if tcp.SYN && tcp.ACK {
			log.Printf("  port %v open", tcp.SrcPort)
		} else {
			// log.Printf("ignoring useless packet")
		}
	}
}

func IPFlow(addr *net.UDPAddr) gopacket.Flow {
	return gopacket.NewFlow(layers.EndpointIPv4, nil, addr.IP.To4())
}

func UDPFlow(addr *net.UDPAddr) gopacket.Flow {
	portBytes := []byte{byte(addr.Port >> 8), byte(addr.Port)}
	return gopacket.NewFlow(layers.EndpointUDPPort, nil, portBytes)
}

// LinkFlow returns a new flow of type EndpointMAC.
func (f *FDDI) LinkFlow() gopacket.Flow {
	return gopacket.NewFlow(EndpointMAC, f.SrcMAC, f.DstMAC)
}

func SubchannelFlow(s int) gopacket.Flow {
	b := make([]byte, 4)
	binary.LittleEndian.PutUint32(b, uint32(s))
	return gopacket.NewFlow(EndpointSubchannel, nil, b)
}

func (r *RUDP) TransportFlow() gopacket.Flow {
	return gopacket.NewFlow(EndpointRUDPPort, []byte{byte(r.SrcPort)}, []byte{byte(r.DstPort)})
}

func (sll *LinuxSLL) LinkFlow() gopacket.Flow {
	return gopacket.NewFlow(EndpointMAC, sll.Addr, nil)
}

func (m *Mach) Flow() gopacket.Flow {
	session := []byte{m.SessionNumber}
	return gopacket.NewFlow(EndpointMachSession, session, session)
}

func (m *MoldUDP64) Flow() gopacket.Flow {
	session := m.Contents[0:10]
	return gopacket.NewFlow(EndpointMoldUDP64Session, session, session)
}

func (e *Ethernet) LinkFlow() gopacket.Flow {
	return gopacket.NewFlow(EndpointMAC, e.SrcMAC, e.DstMAC)
}