func decodeVXLAN(data []byte, p gopacket.PacketBuilder) error {
	vx := &VXLAN{}

	// VNI is a 24bit number, Uint32 requires 32 bits
	var buf [4]byte
	copy(buf[1:], data[4:7])

	// RFC 7348 https://tools.ietf.org/html/rfc7348
	vx.ValidIDFlag = data[0]&0x08 > 0        // 'I' bit per RFC7348
	vx.VNI = binary.BigEndian.Uint32(buf[:]) // VXLAN Network Identifier per RFC7348

	// Group Based Policy https://tools.ietf.org/html/draft-smith-vxlan-group-policy-00
	vx.GBPExtension = data[0]&0x80 > 0                       // 'G' bit per the group policy draft
	vx.GBPDontLearn = data[1]&0x40 > 0                       // 'D' bit - the egress VTEP MUST NOT learn the source address of the encapsulated frame.
	vx.GBPApplied = data[1]&0x80 > 0                         // 'A' bit - indicates that the group policy has already been applied to this packet.
	vx.GBPGroupPolicyID = binary.BigEndian.Uint16(data[2:4]) // Policy ID as per the group policy draft

	// Layer information
	const vxlanLength = 8
	vx.Contents = data[:vxlanLength]
	vx.Payload = data[vxlanLength:]

	p.AddLayer(vx)
	return p.NextDecoder(LinkTypeEthernet)
}

func decodeSCTPEmptyLayer(data []byte, p gopacket.PacketBuilder) error {
	sc := &SCTPEmptyLayer{
		SCTPChunk: decodeSCTPChunk(data),
	}
	p.AddLayer(sc)
	return p.NextDecoder(gopacket.DecodeFunc(decodeWithSCTPChunkTypePrefix))
}

func decodeMach(data []byte, p gopacket.PacketBuilder) (err error) {
	panic("FIXME")
	defer errs.PassE(&err)
	m := &Mach{}
	errs.CheckE(m.DecodeFromBytes(data, p))
	p.AddLayer(m)
	return p.NextDecoder(m.NextLayerType())
}

func decodeMoldUDP64(data []byte, p gopacket.PacketBuilder) error {
	m := &MoldUDP64{}
	if err := m.DecodeFromBytes(data, p); err != nil {
		return err
	}
	p.AddLayer(m)
	return p.NextDecoder(m.NextLayerType())
}

func decodeSCTPShutdown(data []byte, p gopacket.PacketBuilder) error {
	sc := &SCTPShutdown{
		SCTPChunk:        decodeSCTPChunk(data),
		CumulativeTSNAck: binary.BigEndian.Uint32(data[4:8]),
	}
	p.AddLayer(sc)
	return p.NextDecoder(gopacket.DecodeFunc(decodeWithSCTPChunkTypePrefix))
}

func (a TomMessageType) Decode(data []byte, p gopacket.PacketBuilder) error {
	layer := TomMessageTypeMetadata[a].CreateLayer()
	if err := layer.DecodeFromBytes(data, p); err != nil {
		return err
	}
	p.AddLayer(layer)
	return p.NextDecoder(layer.NextLayerType())
}

func decodeLoopback(data []byte, p gopacket.PacketBuilder) error {
	l := Loopback{}
	if err := l.DecodeFromBytes(data, gopacket.NilDecodeFeedback); err != nil {
		return err
	}
	p.AddLayer(&l)
	return p.NextDecoder(l.Family)
}

func decodeSCTPCookieEcho(data []byte, p gopacket.PacketBuilder) error {
	sc := &SCTPCookieEcho{
		SCTPChunk: decodeSCTPChunk(data),
	}
	sc.Cookie = data[4:sc.Length]
	p.AddLayer(sc)
	return p.NextDecoder(gopacket.DecodeFunc(decodeWithSCTPChunkTypePrefix))
}

func decodeICMPv4(data []byte, p gopacket.PacketBuilder) error {
	i := &ICMPv4{}
	err := i.DecodeFromBytes(data, p)
	if err != nil {
		return err
	}
	p.AddLayer(i)
	return p.NextDecoder(gopacket.LayerTypePayload)
}

func decodeDHCPv4(data []byte, p gopacket.PacketBuilder) error {
	dhcp := &DHCPv4{}
	err := dhcp.DecodeFromBytes(data, p)
	if err != nil {
		return err
	}
	p.AddLayer(dhcp)
	return p.NextDecoder(gopacket.LayerTypePayload)
}

func decodeVxlan(data []byte, p gopacket.PacketBuilder) error {
	v := &VXLAN{BaseLayer: BaseLayer{Contents: data}}
	err := v.DecodeFromBytes(data, p)
	p.AddLayer(v)
	if err != nil {
		return err
	}
	return p.NextDecoder(v.NextLayerType())
}

func decodeIPv6HopByHop(data []byte, p gopacket.PacketBuilder) error {
	i := &IPv6HopByHop{}
	err := i.DecodeFromBytes(data, p)
	p.AddLayer(i)
	if err != nil {
		return err
	}
	return p.NextDecoder(i.NextHeader)
}

func decodeIPSecESP(data []byte, p gopacket.PacketBuilder) error {
	i := &IPSecESP{
		BaseLayer: BaseLayer{data, nil},
		SPI:       binary.BigEndian.Uint32(data[:4]),
		Seq:       binary.BigEndian.Uint32(data[4:8]),
		Encrypted: data[8:],
	}
	p.AddLayer(i)
	return nil
}

// decodeDNS decodes the byte slice into a DNS type. It also
// setups the application Layer in PacketBuilder.
func decodeDNS(data []byte, p gopacket.PacketBuilder) error {
	d := &DNS{}
	err := d.DecodeFromBytes(data, p)
	if err != nil {
		return err
	}
	p.AddLayer(d)
	p.SetApplicationLayer(d)
	return nil
}

func decodeSCTPEmptyLayer(data []byte, p gopacket.PacketBuilder) error {
	chunk, err := decodeSCTPChunk(data)
	if err != nil {
		return err
	}
	sc := &SCTPEmptyLayer{
		SCTPChunk: chunk,
	}
	p.AddLayer(sc)
	return p.NextDecoder(gopacket.DecodeFunc(decodeWithSCTPChunkTypePrefix))
}

func decodeCapwapDataKeepAlive(data []byte, p gopacket.PacketBuilder) error {
	length := binary.BigEndian.Uint16(data)
	p.AddLayer(&CapwapDataKeepAlive{
		BaseLayer: layers.BaseLayer{
			Contents: data[:2],
			Payload:  data[2:length],
		},
		MessageElementLength: length,
	})
	return p.NextDecoder(gopacket.LayerTypePayload)
}

func decodeEthernetCTP(data []byte, p gopacket.PacketBuilder) error {
	c := &EthernetCTP{
		SkipCount: binary.LittleEndian.Uint16(data[:2]),
		BaseLayer: BaseLayer{data[:2], data[2:]},
	}
	if c.SkipCount%2 != 0 {
		return fmt.Errorf("EthernetCTP skip count is odd: %d", c.SkipCount)
	}
	p.AddLayer(c)
	return p.NextDecoder(gopacket.DecodeFunc(decodeEthernetCTPFromFunctionType))
}

func decodingLayerDecoder(d layerDecodingLayer, data []byte, p gopacket.PacketBuilder) error {
	err := d.DecodeFromBytes(data, p)
	if err != nil {
		return err
	}
	p.AddLayer(d)
	next := d.NextLayerType()
	if next == gopacket.LayerTypeZero {
		return nil
	}
	return p.NextDecoder(next)
}

// decodePPPoE decodes the PPPoE header (see http://tools.ietf.org/html/rfc2516).
func decodePPPoE(data []byte, p gopacket.PacketBuilder) error {
	pppoe := &PPPoE{
		Version:   data[0] >> 4,
		Type:      data[0] & 0x0F,
		Code:      PPPoECode(data[1]),
		SessionId: binary.BigEndian.Uint16(data[2:4]),
		Length:    binary.BigEndian.Uint16(data[4:6]),
	}
	pppoe.BaseLayer = BaseLayer{data[:6], data[6 : 6+pppoe.Length]}
	p.AddLayer(pppoe)
	return p.NextDecoder(pppoe.Code)
}

func decodeDot11NoFCS(data []byte, p gopacket.PacketBuilder) error {
	payload := append(data, 0, 0, 0, 0)
	h := crc32.NewIEEE()
	h.Write(data)
	binary.LittleEndian.PutUint32(payload[len(data):], h.Sum32())
	p.AddLayer(&Dot11NoFCS{
		BaseLayer: layers.BaseLayer{
			Payload: payload,
		},
	})
	return p.NextDecoder(layers.LayerTypeDot11)
}