// writeARP writes an ARP request for each address on our local network to the
// pcap handle.
func writeARP(handle *pcap.Handle, iface *net.Interface, addr *net.IPNet) error {
	// Set up all the layers' fields we can.
	eth := layers.Ethernet{
		SrcMAC:       iface.HardwareAddr,
		DstMAC:       net.HardwareAddr{0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
		EthernetType: layers.EthernetTypeARP,
	}
	arp := layers.ARP{
		AddrType:          layers.LinkTypeEthernet,
		Protocol:          layers.EthernetTypeIPv4,
		HwAddressSize:     6,
		ProtAddressSize:   4,
		Operation:         layers.ARPRequest,
		SourceHwAddress:   []byte(iface.HardwareAddr),
		SourceProtAddress: []byte(addr.IP),
		DstHwAddress:      []byte{0, 0, 0, 0, 0, 0},
	}
	// Set up buffer and options for serialization.
	buf := gopacket.NewSerializeBuffer()
	opts := gopacket.SerializeOptions{
		FixLengths:       true,
		ComputeChecksums: true,
	}
	// Send one packet for every address.
	for ip := range ips(addr) {
		arp.DstProtAddress = []byte(ip)
		gopacket.SerializeLayers(buf, opts, &eth, &arp)
		if err := handle.WritePacketData(buf.Bytes()); err != nil {
			return err
		}
	}
	return nil
}

func main() {
	flag.Parse()
	var handle *pcap.Handle
	var err error
	if *fname != "" {
		if handle, err = pcap.OpenOffline(*fname); err != nil {
			log.Fatalln("PCAP OpenOffline error:", err)
		}
	} else {
		if handle, err = pcap.OpenLive(*iface, int32(*snaplen), true, time.Second); err != nil {
			log.Fatalln("PCAP OpenLive error:", err)
		}
		if *tstype != "" {
			if t, err := pcap.TimestampSourceFromString(*tstype); err != nil {
				log.Fatalf("Supported timestamp types: %v", handle.SupportedTimestamps())
			} else if err := handle.SetTimestampSource(t); err != nil {
				log.Fatalf("Supported timestamp types: %v", handle.SupportedTimestamps())
			}
		}
		if len(flag.Args()) > 0 {
			bpffilter := strings.Join(flag.Args(), " ")
			fmt.Fprintf(os.Stderr, "Using BPF filter %q\n", bpffilter)
			if err = handle.SetBPFFilter(bpffilter); err != nil {
				log.Fatalln("BPF filter error:", err)
			}
		}
	}
	dumpcommand.Run(handle)
}

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 nextPkt(h *pcap.Handle) (p Packet) {
	for {
		pbuf, _, err := h.ReadPacketData()
		if err != nil {
			panic(err)
		}
		var ok bool
		if p, ok = NewPkt(pbuf); ok {
			return
		}
	}
	return
}

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
		}
	}
}

func main() {
	flag.Parse()
	var handle *pcap.Handle
	var err error
	if *fname != "" {
		if handle, err = pcap.OpenOffline(*fname); err != nil {
			log.Fatalln("PCAP OpenOffline error:", err)
		}
	} else {
		if handle, err = pcap.OpenLive(*iface, int32(*snaplen), true, time.Second); err != nil {
			log.Fatalln("PCAP OpenLive error:", err)
		}
		if len(flag.Args()) > 0 {
			bpffilter := strings.Join(flag.Args(), " ")
			fmt.Fprintf(os.Stderr, "Using BPF filter %q\n", bpffilter)
			if err = handle.SetBPFFilter(bpffilter); err != nil {
				log.Fatalln("BPF filter error:", err)
			}
		}
	}
	dumpcommand.Run(handle)
}

//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
		}
	}
}

func tryCapture(iface net.Interface) error {
	if iface.Name[:2] == "lo" {
		return fmt.Errorf("skipping loopback")
	}
	var h *pcap.Handle
	var err error
	switch *mode {
	case "basic":
		h, err = pcap.OpenLive(iface.Name, 65536, false, time.Second*3)
		if err != nil {
			return fmt.Errorf("openlive: %v", err)
		}
		defer h.Close()
	case "filtered":
		h, err = pcap.OpenLive(iface.Name, 65536, false, time.Second*3)
		if err != nil {
			return fmt.Errorf("openlive: %v", err)
		}
		defer h.Close()
		if err := h.SetBPFFilter("port 80 or port 443"); err != nil {
			return fmt.Errorf("setbpf: %v", err)
		}
	case "timestamp":
		u, err := pcap.NewInactiveHandle(iface.Name)
		if err != nil {
			return err
		}
		defer u.CleanUp()
		if err = u.SetSnapLen(65536); err != nil {
			return err
		} else if err = u.SetPromisc(false); err != nil {
			return err
		} else if err = u.SetTimeout(time.Second * 3); err != nil {
			return err
		}
		sources := u.SupportedTimestamps()
		if len(sources) == 0 {
			return fmt.Errorf("no supported timestamp sources")
		} else if err := u.SetTimestampSource(sources[0]); err != nil {
			return fmt.Errorf("settimestampsource(%v): %v", sources[0], err)
		} else if h, err = u.Activate(); err != nil {
			return fmt.Errorf("could not activate: %v", err)
		}
		defer h.Close()
	default:
		panic("Invalid --mode: " + *mode)
	}
	go generatePackets()
	h.ReadPacketData() // Do one dummy read to clear any timeouts.
	data, ci, err := h.ReadPacketData()
	if err != nil {
		return fmt.Errorf("readpacketdata: %v", err)
	}
	log.Printf("Read packet, %v bytes, CI: %+v", len(data), ci)
	return nil
}