Golang Packet.NetworkLayer方法代碼示例

func (b *Benchmark) decodePacket(pkt gopacket.Packet) (key *FiveTuple, payload []byte) {
	ipv4, ok := pkt.NetworkLayer().(*layers.IPv4)

	if !ok {
		return // Ignore packets that aren't IPv4
	}

	if ipv4.FragOffset != 0 || (ipv4.Flags&layers.IPv4MoreFragments) != 0 {
		return // Ignore fragmented packets.
	}

	var stream FiveTuple

	stream.protocol = ipv4.Protocol
	stream.srcAddr = ipv4.SrcIP
	stream.dstAddr = ipv4.DstIP

	switch t := pkt.TransportLayer().(type) {
	case *layers.TCP:
		stream.srcPort = uint16(t.SrcPort)
		stream.dstPort = uint16(t.DstPort)
		return &stream, t.Payload

	case *layers.UDP:
		stream.srcPort = uint16(t.SrcPort)
		stream.dstPort = uint16(t.DstPort)
		return &stream, t.Payload
	}

	return
}

// IsUdpPacket returns true if the packet is of UDP type
func IsUdpPacket(packet gopacket.Packet) bool {
	if packet == nil {
		return false
	}
	if packet.NetworkLayer() == nil || packet.TransportLayer() == nil || packet.TransportLayer().LayerType() != layers.LayerTypeUDP {
		return false
	}
	return true
}

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 SendPacket(packet gopacket.Packet,
	connectionWaitGroup *sync.WaitGroup,
	mongodHost string,
	mongodPort string) {
	// If packet contains a mongo message
	if packet.ApplicationLayer() != nil {
		payload := packet.ApplicationLayer().Payload()
		delta := GetPacketTime(packet).Sub(packetMinTimestamp)

		// Get timestamp's delta from first packet
		// Get mongo wire protocol payload
		mongoPacket := MongoPacket{
			payload: payload,
			delta:   delta,
		}

		transportLayer := packet.TransportLayer()
		networkLayer := packet.NetworkLayer()

		var srcIp string
		var srcPort string

		if networkLayer.LayerType() == layers.LayerTypeIPv4 {
			ip4header := networkLayer.LayerContents()
			// Convert binary to IP string
			srcIp = strconv.Itoa(int(ip4header[12])) + "." +
				strconv.Itoa(int(ip4header[13])) + "." +
				strconv.Itoa(int(ip4header[14])) + "." +
				strconv.Itoa(int(ip4header[15]))
		}
		if transportLayer.LayerType() == layers.LayerTypeTCP {
			tcpHeader := transportLayer.LayerContents()
			// Hack to be able to use convert what should be a uint16 to string
			tcpHeaderSrcPort := []byte{0, 0, tcpHeader[0], tcpHeader[1]}
			srcPort = strconv.Itoa(int(binary.BigEndian.Uint32(tcpHeaderSrcPort)))
		}

		src := srcIp + ":" + srcPort

		if mConnection, ok := mapHostConnection[src]; ok {
			mConnection.Send(mongoPacket)
		} else {
			connectionWaitGroup.Add(1)
			mConnection := NewMongoConnection(mongodHost, mongodPort, 100)
			mapHostConnection[src] = mConnection
			go mConnection.ExecuteConnection(connectionWaitGroup)
			mConnection.Send(mongoPacket)
		}
	}
}

func onRecvPing(pkt gopacket.Packet, icmp *layers.ICMPv4, ci *gopacket.CaptureInfo) {
	payload := icmp.Payload
	if payload == nil || len(payload) <= 0 {
		return
	}
	sendStamp := binary.LittleEndian.Uint64(payload)
	if sendStamp < 1000000 {
		return
	}
	delay := ci.Timestamp.UnixNano() - int64(sendStamp)

	probeResult := &types.ProbeResult{}
	probeResult.Src = pkt.NetworkLayer().NetworkFlow().Dst().Raw()
	probeResult.Dest = pkt.NetworkLayer().NetworkFlow().Src().Raw()
	probeResult.Delay = int(delay / 1000)
	probeResult.Stamp = ci.Timestamp.Unix()
	probeResult.Type = types.ProbeTypePing
	db.InsertProbeResult(probeResult)
}

// handle a network packet
func handlePacket(p gopacket.Packet) {
	flow := p.NetworkLayer().NetworkFlow()

	// get the destination ip address
	dst := flow.Dst().String()

	// check if we need to count packets
	if !locals[dst] && !offenders[dst] {
		//log.Printf("%s -> %s", flow.Src(), flow.Dst())
		bkt := getRateLimit(dst)
		tokens := bkt.TakeAvailable(1)

		// if all tokens are used, ban the ip address
		// because it's most likely trying to abuse our bandwidth
		if tokens == 0 {
			offenders[dst] = true
			log.Printf("Offender %s", dst)
			output, err := exec.Command("iptables", "-A", "INPUT", "-s", dst, "-j", "DROP").CombinedOutput()
			if err != nil {
				log.Printf("Failed banning IP: %s %s %s", dst, err.Error(), string(output))
			}
		}
	}
}

func originalSize(packet gopacket.Packet) int {
	return len(packet.NetworkLayer().LayerPayload()) + len(packet.NetworkLayer().LayerContents())
}

func handlePacket(handle *pcap.Handle, packet gopacket.Packet) {
	ethLayer := packet.LinkLayer()
	if ethLayer == nil {
		return
	}
	eth, ok := ethLayer.(*layers.Ethernet)
	if !ok {
		return
	}

	ipLayer := packet.NetworkLayer()
	if ipLayer == nil {
		return
	}

	ip, ok := ipLayer.(*layers.IPv4)
	if !ok {
		return
	}

	tcpLayer := packet.Layer(layers.LayerTypeTCP)
	if tcpLayer == nil {
		return
	}
	tcp, ok := tcpLayer.(*layers.TCP)
	if !ok {
		return
	}

	// 服務器回應 SYN 請求
	if tcp.SYN == true && tcp.ACK == true {
		ttl := uint8(0)

		switch {
		case ip.TTL > 128:
			//Solaris/AIX
			ttl = 254 - ip.TTL
		case ip.TTL > 64:
			// windows
			ttl = 128 - ip.TTL
		default:
			// linux
			ttl = 64 - ip.TTL
		}

		switch {
		case ttl > 10:
			ttl -= 4
		case ttl > 5:
			ttl -= 2
		case ttl > 2:
			ttl -= 1
		default:
			return
		}

		ack := tcp.Seq + uint32(len(tcp.Payload)) + 1
		data := []byte{1, 2, 3, 4, 5, 6, 7, 8, 9}
		seq := tcp.Ack
		sendPacket(handle, eth.DstMAC, eth.SrcMAC, ip.DstIP, ip.SrcIP, tcp.DstPort, tcp.SrcPort, ip.Id+123, ttl, seq, ack, 258, data)
		seq += 2048
		sendPacket(handle, eth.DstMAC, eth.SrcMAC, ip.DstIP, ip.SrcIP, tcp.DstPort, tcp.SrcPort, ip.Id+123, ttl, seq, ack, 258, nil)
		//go fmt.Printf("偽重置 %v:%v 的 tcp 連接。\r\n", ip.SrcIP, tcp.SrcPort)
	}
}