Golang Packet.Layers方法代碼示例

func (p *processor) decodeAppLayer(pkt gopacket.Packet) error {
	var moldUdp64Decoder gopacket.Decoder = nasdaq.LayerTypeMoldUDP64
	var ittoDecoder gopacket.Decoder = nasdaq.LayerTypeItto
	//log.Println("decodeAppLayer", pkt)
	transpLayer := pkt.TransportLayer()
	appLayer := pkt.ApplicationLayer()
	if transpLayer == nil || transpLayer.LayerType() != layers.LayerTypeUDP || appLayer == nil {
		return nil
	}

	packetBuilder := pkt.(gopacket.PacketBuilder)
	if packetBuilder == nil {
		panic("packet is not packetBuilder")
	}
	if appLayer.LayerType() != gopacket.LayerTypePayload {
		panic("appLayer is not LayerTypePayload")
	}
	data := appLayer.LayerContents()
	if err := moldUdp64Decoder.Decode(data, packetBuilder); err != nil {
		return err
	}
	for _, l := range pkt.Layers() {
		if mb, ok := l.(*nasdaq.MoldUDP64MessageBlockChained); ok {
			ittoDecoder.Decode(mb.Payload, packetBuilder)
		}
	}
	return nil
}

func handlePacket(packet gopacket.Packet) {

	// Get the TCP layer from this packet
	tcpLayer := packet.Layer(layers.LayerTypeTCP)

	if tcpLayer != nil {

		// Get actual TCP data from this layer
		tcp, _ := tcpLayer.(*layers.TCP)
		fmt.Printf("From: src port %6d\tTo: dst port %6d\t", tcp.SrcPort, tcp.DstPort)
		fmt.Printf("Ack: %12v\t", tcp.Ack)
	}

	// Iterate over all layers, printing out each layer type
	for _, layer := range packet.Layers() {
		layerType := layer.LayerType()
		fmt.Printf("%8v %5v", layerType, len(layer.LayerPayload()))
	}

	applicationLayer := packet.ApplicationLayer()
	if applicationLayer != nil {
		fmt.Println("Application layer/Payload found.")
		//fmt.Printf("%s\n", applicationLayer.Payload())
	}
	fmt.Println("")

}

func checkLayers(p gopacket.Packet, want []gopacket.LayerType, t *testing.T) {
	layers := p.Layers()
	t.Log("Checking packet layers, want", want)
	for _, l := range layers {
		t.Logf("  Got layer %v, %d bytes, payload of %d bytes", l.LayerType(),
			len(l.LayerContents()), len(l.LayerPayload()))
	}
	t.Log(p)
	if len(layers) != len(want) {
		t.Errorf("  Number of layers mismatch: got %d want %d", len(layers),
			len(want))
		return
	}
	for i, l := range layers {
		if l.LayerType() != want[i] {
			t.Errorf("  Layer %d mismatch: got %v want %v", i, l.LayerType(),
				want[i])
		}
	}
}

func printPacketInfo(packet gopacket.Packet) {
	// Let's see if the packet is an ethernet packet
	ethernetLayer := packet.Layer(layers.LayerTypeEthernet)
	if ethernetLayer != nil {
		fmt.Println("Ethernet layer detected.")
		ethernetPacket, _ := ethernetLayer.(*layers.Ethernet)
		fmt.Println("Source MAC: ", ethernetPacket.SrcMAC)
		fmt.Println("Destination MAC: ", ethernetPacket.DstMAC)
		// Ethernet type is typically IPv4 but could be ARP or other
		fmt.Println("Ethernet type: ", ethernetPacket.EthernetType)
		fmt.Println()
	}

	// Let's see if the packet is IP (even though the ether type told us)
	ipLayer := packet.Layer(layers.LayerTypeIPv4)
	if ipLayer != nil {
		fmt.Println("IPv4 layer detected.")
		ip, _ := ipLayer.(*layers.IPv4)

		// IP layer variables:
		// Version (Either 4 or 6)
		// IHL (IP Header Length in 32-bit words)
		// TOS, Length, Id, Flags, FragOffset, TTL, Protocol (TCP?),
		// Checksum, SrcIP, DstIP
		fmt.Printf("From %s to %s\n", ip.SrcIP, ip.DstIP)
		fmt.Println("Protocol: ", ip.Protocol)
		fmt.Println()
	}

	// Let's see if the packet is TCP
	tcpLayer := packet.Layer(layers.LayerTypeTCP)
	if tcpLayer != nil {
		fmt.Println("TCP layer detected.")
		tcp, _ := tcpLayer.(*layers.TCP)

		// TCP layer variables:
		// SrcPort, DstPort, Seq, Ack, DataOffset, Window, Checksum, Urgent
		// Bool flags: FIN, SYN, RST, PSH, ACK, URG, ECE, CWR, NS
		fmt.Printf("From port %d to %d\n", tcp.SrcPort, tcp.DstPort)
		fmt.Println("Sequence number: ", tcp.Seq)
		fmt.Println()
	}

	// Iterate over all layers, printing out each layer type
	fmt.Println("All packet layers:")
	for _, layer := range packet.Layers() {
		fmt.Println("- ", layer.LayerType())
	}

	// When iterating through packet.Layers() above,
	// if it lists Payload layer then that is the same as
	// this applicationLayer. applicationLayer contains the payload
	applicationLayer := packet.ApplicationLayer()
	if applicationLayer != nil {
		fmt.Println("Application layer/Payload found.")
		fmt.Printf("%s\n", applicationLayer.Payload())

		// Search for a string inside the payload
		if strings.Contains(string(applicationLayer.Payload()), "HTTP") {
			fmt.Println("HTTP found!")
		}
	}

	// Check for errors
	if err := packet.ErrorLayer(); err != nil {
		fmt.Println("Error decoding some part of the packet:", err)
	}
}

func gatherPacketLayersInfo(event common.MapStr, packet gopacket.Packet) {
	// see https://godoc.org/github.com/google/gopacket#hdr-Pointers_To_Known_Layers
	//   Pointers To Known Layers:
	//   During decoding, certain layers are stored in the packet as well-known layer types.
	//   For example, IPv4 and IPv6 are both considered NetworkLayer layers,
	//   while TCP and UDP are both TransportLayer layers.
	//   We support 4 layers, corresponding to the 4 layers of the TCP/IP layering scheme
	//   (roughly anagalous to layers 2, 3, 4, and 7 of the OSI model).
	//   To access these, you can use the:
	//     packet.LinkLayer,
	//     packet.NetworkLayer,
	//     packet.TransportLayer, and
	//     packet.ApplicationLayer functions.
	//   Each of these functions returns a corresponding interface (gopacket.{Link,Network,Transport,Application}Layer).
	//   The first three provide methods for getting src/dst addresses for that particular layer,
	//   while the final layer provides a Payload function to get payload data.

	// use "packet.Dump()" as a fail-safe to capture all available layers for a packet,
	// just in case we encounter something unexpected in the unified2 file or we
	// have neglected to handle a particular layer explicitly
	event["packet_dump"] = packet.Dump()
	// "packet.Dump()" is very verbose, i.e. a large amount of text, but that's ok

	// capture the name of the layers found
	var packet_layers []string
	for _, layer := range packet.Layers() {
		packet_layers = append(packet_layers, fmt.Sprintf("%v", layer.LayerType()))
	}
	event["packet_layers"] = packet_layers

	// Ethernet layer?
	ethernetLayer := packet.Layer(layers.LayerTypeEthernet)
	if ethernetLayer != nil {
		ethernetPacket, _ := ethernetLayer.(*layers.Ethernet)
		event["ethernet_src_mac"] = fmt.Sprintf("%v", ethernetPacket.SrcMAC)
		event["ethernet_dst_mac"] = fmt.Sprintf("%v", ethernetPacket.DstMAC)
		// ethernet type is typically IPv4 but could be ARP or other
		event["ethernet_type"] = fmt.Sprintf("%v", ethernetPacket.EthernetType)
		// Length is only set if a length field exists within this header.  Ethernet
		// headers follow two different standards, one that uses an EthernetType, the
		// other which defines a length the follows with a LLC header (802.3).  If the
		// former is the case, we set EthernetType and Length stays 0.  In the latter
		// case, we set Length and EthernetType = EthernetTypeLLC.
		event["ethernet_length"] = fmt.Sprintf("%v", ethernetPacket.Length)
	}

	// IPv4 layer?
	ipLayer := packet.Layer(layers.LayerTypeIPv4)
	if ipLayer != nil {
		ip, _ := ipLayer.(*layers.IPv4)
		event["ip_version"] = ip.Version
		event["ip_ihl"] = ip.IHL
		event["ip_tos"] = ip.TOS
		event["ip_length"] = ip.Length
		event["ip_id"] = ip.Id
		event["ip_flags"] = ip.Flags
		event["ip_fragoffset"] = ip.FragOffset
		event["ip_ttl"] = ip.TTL
		event["ip_protocol"] = ip.Protocol
		event["ip_checksum"] = ip.Checksum
		event["ip_src_ip"] = ip.SrcIP
		event["ip_dst_ip"] = ip.DstIP
		event["ip_options"] = ip.Options // maybe? fmt.Sprintf("%v", ip.Options)
		event["ip_padding"] = ip.Padding
	}

	// IPv6 layer?
	ip6Layer := packet.Layer(layers.LayerTypeIPv6)
	if ip6Layer != nil {
		ip6, _ := ip6Layer.(*layers.IPv6)
		event["ip6_version"] = ip6.Version
		event["ip6_trafficclass"] = ip6.TrafficClass
		event["ip6_flowlabel"] = ip6.FlowLabel
		event["ip6_length"] = ip6.Length
		event["ip6_nextheader"] = ip6.NextHeader
		event["ip6_hoplimit"] = ip6.HopLimit
		event["ip6_src_ip"] = ip6.SrcIP
		event["ip6_dst_ip"] = ip6.DstIP
		event["ip6_hopbyhop"] = ip6.HopByHop
	}

	// see: gopacket/layers folder ... what layers are needed for Snort/Suricata alerts?
	// ICMPv4 layer?
	// ICMPv6 layer?
	// ARP layer?

	// UDP layer?
	udpLayer := packet.Layer(layers.LayerTypeUDP)
	if udpLayer != nil {
		udp, _ := udpLayer.(*layers.UDP)
		event["udp_src_port"] = udp.SrcPort
		event["udp_dst_port"] = udp.DstPort
		event["udp_length"] = udp.Length
		event["udp_checksum"] = udp.Checksum
	}

	// TCP layer?
	tcpLayer := packet.Layer(layers.LayerTypeTCP)
	if tcpLayer != nil {
		tcp, _ := tcpLayer.(*layers.TCP)
//.........這裏部分代碼省略.........