Golang Handle.LinkType方法代碼示例

func main() {
	defer util.Run()()
	var handle *pcap.Handle
	var err error

	// Set up pcap packet capture
	if *fname != "" {
		log.Printf("Reading from pcap dump %q", *fname)
		handle, err = pcap.OpenOffline(*fname)
	} else {
		log.Printf("Starting capture on interface %q", *iface)
		handle, err = pcap.OpenLive(*iface, int32(*snaplen), true, pcap.BlockForever)
	}
	if err != nil {
		log.Fatal(err)
	}

	if err := handle.SetBPFFilter(*filter); err != nil {
		log.Fatal(err)
	}

	// Set up assembly
	streamFactory := &httpStreamFactory{}
	streamPool := tcpassembly.NewStreamPool(streamFactory)
	assembler := tcpassembly.NewAssembler(streamPool)

	log.Println("reading in packets")
	// Read in packets, pass to assembler.
	packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
	packets := packetSource.Packets()
	ticker := time.Tick(time.Minute)
	for {
		select {
		case packet := <-packets:
			// A nil packet indicates the end of a pcap file.
			if packet == nil {
				return
			}
			if *logAllPackets {
				log.Println(packet)
			}
			if packet.NetworkLayer() == nil || packet.TransportLayer() == nil || packet.TransportLayer().LayerType() != layers.LayerTypeTCP {
				log.Println("Unusable packet")
				continue
			}
			tcp := packet.TransportLayer().(*layers.TCP)
			assembler.AssembleWithTimestamp(packet.NetworkLayer().NetworkFlow(), tcp, packet.Metadata().Timestamp)

		case <-ticker:
			// Every minute, flush connections that haven't seen activity in the past 2 minutes.
			assembler.FlushOlderThan(time.Now().Add(time.Minute * -2))
		}
	}
}

func (tap *Wiretap) capture(handle *pcap.Handle, channel chan gopacket.Packet) {
	defer handle.Close()

	src := gopacket.NewPacketSource(handle, handle.LinkType())
	src.DecodeOptions = gopacket.NoCopy

	for {
		packet, err := src.NextPacket()
		if err == io.EOF {
			return
		} else if err == nil {
			channel <- packet
		}
	}
}

//startCapture captures all packets on any interface for an unlimited duration.
//Packets can be filtered by a BPF filter string. (E.g. tcp port 22)
func capture(snaplen int32, quit chan bool, captureReady chan bool, pcapFile string) error {
	var handle *pcap.Handle
	var err error
	if pcapFile != "" {
		log.Println("Reading packet loss data from pcap-file:", pcapFile)
		handle, err = pcap.OpenOffline(pcapFile)
	} else {
		//https://godoc.org/code.google.com/p/gopacket/pcap
		//This might have been the culprit
		//Alternative to try: 250*time.Millisecond
		handle, err = pcap.OpenLive("any", snaplen, true, 250*time.Millisecond)
	}

	if err != nil {
		log.Println("Error while start capturing packets", err)
		return err
	}

	packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
	captureReady <- true

	for {
		select {
		case packet := <-packetSource.Packets():
			if packet != nil {
				if packet.Layer(layers.LayerTypeIPSecESP) != nil {
					putChannel(packet, ipSecChannel)
				}
				if packet.Layer(layers.LayerTypeICMPv4) != nil {
					putChannel(packet, icmpChannel)
				}
			}
		case <-quit:
			log.Println("Received quit message, stopping Listener.")
			return nil
		}
	}
}