Ejemplo n.º 1
0
func TestRawConnUnicastSocketOptions(t *testing.T) {
	switch runtime.GOOS {
	case "nacl", "plan9", "solaris":
		t.Skipf("not supported on %q", runtime.GOOS)
	}
	if os.Getuid() != 0 {
		t.Skip("must be root")
	}
	ifi := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagLoopback)
	if ifi == nil {
		t.Skipf("not available on %q", runtime.GOOS)
	}

	c, err := net.ListenPacket("ip4:icmp", "127.0.0.1")
	if err != nil {
		t.Fatal(err)
	}
	defer c.Close()

	r, err := ipv4.NewRawConn(c)
	if err != nil {
		t.Fatal(err)
	}

	testUnicastSocketOptions(t, r)
}
Ejemplo n.º 2
0
func TestRawConnUnicastSocketOptions(t *testing.T) {
	switch runtime.GOOS {
	case "nacl", "plan9":
		t.Skipf("not supported on %s", runtime.GOOS)
	}
	if m, ok := nettest.SupportsRawIPSocket(); !ok {
		t.Skip(m)
	}
	ifi := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagLoopback)
	if ifi == nil {
		t.Skipf("not available on %s", runtime.GOOS)
	}

	c, err := net.ListenPacket("ip4:icmp", "127.0.0.1")
	if err != nil {
		t.Fatal(err)
	}
	defer c.Close()

	r, err := ipv4.NewRawConn(c)
	if err != nil {
		t.Fatal(err)
	}

	testUnicastSocketOptions(t, r)
}
func TestRawConnMulticastSocketOptions(t *testing.T) {
	switch runtime.GOOS {
	case "nacl", "plan9":
		t.Skipf("not supported on %s", runtime.GOOS)
	}
	if m, ok := nettest.SupportsRawIPSocket(); !ok {
		t.Skip(m)
	}
	ifi := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagMulticast|net.FlagLoopback)
	if ifi == nil {
		t.Skipf("not available on %s", runtime.GOOS)
	}

	for _, tt := range rawConnMulticastSocketOptionTests {
		c, err := net.ListenPacket("ip4:icmp", "0.0.0.0")
		if err != nil {
			t.Fatal(err)
		}
		defer c.Close()
		r, err := ipv4.NewRawConn(c)
		if err != nil {
			t.Fatal(err)
		}
		defer r.Close()

		if tt.src == nil {
			testMulticastSocketOptions(t, r, ifi, tt.grp)
		} else {
			testSourceSpecificMulticastSocketOptions(t, r, ifi, tt.grp, tt.src)
		}
	}
}
Ejemplo n.º 4
0
func TestRawConnMulticastSocketOptions(t *testing.T) {
	switch runtime.GOOS {
	case "nacl", "plan9", "solaris":
		t.Skipf("not supported on %q", runtime.GOOS)
	}
	if os.Getuid() != 0 {
		t.Skip("must be root")
	}
	ifi := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagMulticast|net.FlagLoopback)
	if ifi == nil {
		t.Skipf("not available on %q", runtime.GOOS)
	}

	c, err := net.ListenPacket("ip4:icmp", "0.0.0.0")
	if err != nil {
		t.Fatalf("net.ListenPacket failed: %v", err)
	}
	defer c.Close()

	r, err := ipv4.NewRawConn(c)
	if err != nil {
		t.Fatalf("ipv4.NewRawConn failed: %v", err)
	}

	testMulticastSocketOptions(t, r, ifi, &net.IPAddr{IP: net.IPv4(224, 0, 0, 250)}) /// see RFC 4727
}
Ejemplo n.º 5
0
func main() {
	flag.Parse()
	ip := net.ParseIP(*dst)
	if ip == nil {
		log.Fatal("destination not found")
	}

	c, err := net.ListenPacket(fmt.Sprintf("ip4:%d", *proto), "0.0.0.0")
	if err != nil {
		log.Fatal(err)
	}
	defer c.Close()
	p, err := ipv4.NewRawConn(c)
	if err != nil {
		log.Fatal(err)
	}

	b := []byte("HELLO-R-U-THERE")
	h := &ipv4.Header{
		Version:  ipv4.Version,
		Len:      ipv4.HeaderLen,
		TotalLen: ipv4.HeaderLen + len(b),
		Protocol: *proto,
		Dst:      ip.To4(),
	}
	if err := p.WriteTo(h, b, nil); err != nil {
		log.Println(err)
	}
}
Ejemplo n.º 6
0
func (i *TCPStreamInjector) Init(netInterface string) error {
	var err error
	i.packetConn, err = net.ListenPacket("ip4:tcp", netInterface)
	if err != nil {
		return err
	}
	i.rawConn, err = ipv4.NewRawConn(i.packetConn)
	return err
}
Ejemplo n.º 7
0
func ExampleRawConn_advertisingOSPFHello() {
	c, err := net.ListenPacket(fmt.Sprintf("ip4:%d", iana.ProtocolOSPFIGP), "0.0.0.0") // OSPF for IPv4
	if err != nil {
		log.Fatal(err)
	}
	defer c.Close()
	r, err := ipv4.NewRawConn(c)
	if err != nil {
		log.Fatal(err)
	}

	en0, err := net.InterfaceByName("en0")
	if err != nil {
		log.Fatal(err)
	}
	allSPFRouters := net.IPAddr{IP: net.IPv4(224, 0, 0, 5)}
	if err := r.JoinGroup(en0, &allSPFRouters); err != nil {
		log.Fatal(err)
	}
	defer r.LeaveGroup(en0, &allSPFRouters)

	hello := make([]byte, 24) // fake hello data, you need to implement this
	ospf := make([]byte, 24)  // fake ospf header, you need to implement this
	ospf[0] = 2               // version 2
	ospf[1] = 1               // hello packet
	ospf = append(ospf, hello...)
	iph := &ipv4.Header{
		Version:  ipv4.Version,
		Len:      ipv4.HeaderLen,
		TOS:      iana.DiffServCS6,
		TotalLen: ipv4.HeaderLen + len(ospf),
		TTL:      1,
		Protocol: iana.ProtocolOSPFIGP,
		Dst:      allSPFRouters.IP.To4(),
	}

	var cm *ipv4.ControlMessage
	switch runtime.GOOS {
	case "darwin", "linux":
		cm = &ipv4.ControlMessage{IfIndex: en0.Index}
	default:
		if err := r.SetMulticastInterface(en0); err != nil {
			log.Fatal(err)
		}
	}
	if err := r.WriteTo(iph, ospf, cm); err != nil {
		log.Fatal(err)
	}
}
Ejemplo n.º 8
0
Archivo: ping.go Proyecto: conoro/netx
// Start kicks off the pinging process. It takes the list of IP addresses added by
// AddIPs() and sends ICMP ECHO_REQUEST to all of them at the specified Interval.
// Results are sent via the returned channel. The caller is expected to read the
// channel so it won't get blocked.
//
// Only a single Start can be called at a time. If the second call to Start is made,
// and error will be returned.
func (this *Pinger) Start() (<-chan *PingResult, error) {
	if !atomic.CompareAndSwapInt64(&this.pid, 0, int64(os.Getpid()&0xffff)) {
		return nil, fmt.Errorf("ping/Start: Pinger already running")
	}

	switch runtime.GOOS {
	case "nacl", "plan9", "solaris", "windows":
		return nil, fmt.Errorf("ping/Start: Operation not supported on %q", runtime.GOOS)
	}

	if os.Getuid() != 0 {
		return nil, fmt.Errorf("ping/Start: User must be root")
	}

	this.updateParams()

	if len(this.payload) < this.Size {
		this.payload = make([]byte, this.Size)
	} else {
		this.payload = this.payload[:this.Size]
	}

	var err error

	this.pconn, err = net.ListenPacket("ip4:icmp", "0.0.0.0")
	if err != nil {
		return nil, err
	}

	this.rconn, err = ipv4.NewRawConn(this.pconn)
	if err != nil {
		return nil, err
	}

	cf := ipv4.FlagTTL | ipv4.FlagDst | ipv4.FlagInterface

	if err := this.rconn.SetControlMessage(cf, true); err != nil {
		//glog.Errorf("ping/sender: Error setting control message: %v", err)
		return nil, err
	}

	this.wg.Add(1)
	go this.receiver()

	this.wg.Add(1)
	go this.sender()

	return this.reschan, nil
}
func TestIPPerInterfaceSingleRawConnWithSingleGroupListener(t *testing.T) {
	switch runtime.GOOS {
	case "nacl", "plan9", "windows":
		t.Skipf("not supported on %s", runtime.GOOS)
	}
	if testing.Short() {
		t.Skip("to avoid external network")
	}
	if m, ok := nettest.SupportsRawIPSocket(); !ok {
		t.Skip(m)
	}

	gaddr := net.IPAddr{IP: net.IPv4(224, 0, 0, 254)} // see RFC 4727
	type ml struct {
		c   *ipv4.RawConn
		ifi *net.Interface
	}
	var mlt []*ml

	ift, err := net.Interfaces()
	if err != nil {
		t.Fatal(err)
	}
	for i, ifi := range ift {
		ip, ok := nettest.IsMulticastCapable("ip4", &ifi)
		if !ok {
			continue
		}
		c, err := net.ListenPacket("ip4:253", ip.String()) // unicast address
		if err != nil {
			t.Fatal(err)
		}
		defer c.Close()
		r, err := ipv4.NewRawConn(c)
		if err != nil {
			t.Fatal(err)
		}
		if err := r.JoinGroup(&ifi, &gaddr); err != nil {
			t.Fatal(err)
		}
		mlt = append(mlt, &ml{r, &ift[i]})
	}
	for _, m := range mlt {
		if err := m.c.LeaveGroup(m.ifi, &gaddr); err != nil {
			t.Fatal(err)
		}
	}
}
func TestIPSingleRawConnWithSingleGroupListener(t *testing.T) {
	switch runtime.GOOS {
	case "nacl", "plan9", "windows":
		t.Skipf("not supported on %s", runtime.GOOS)
	}
	if testing.Short() {
		t.Skip("to avoid external network")
	}
	if m, ok := nettest.SupportsRawIPSocket(); !ok {
		t.Skip(m)
	}

	c, err := net.ListenPacket("ip4:icmp", "0.0.0.0") // wildcard address
	if err != nil {
		t.Fatal(err)
	}
	defer c.Close()

	r, err := ipv4.NewRawConn(c)
	if err != nil {
		t.Fatal(err)
	}
	gaddr := net.IPAddr{IP: net.IPv4(224, 0, 0, 254)} // see RFC 4727
	var mift []*net.Interface

	ift, err := net.Interfaces()
	if err != nil {
		t.Fatal(err)
	}
	for i, ifi := range ift {
		if _, ok := nettest.IsMulticastCapable("ip4", &ifi); !ok {
			continue
		}
		if err := r.JoinGroup(&ifi, &gaddr); err != nil {
			t.Fatal(err)
		}
		mift = append(mift, &ift[i])
	}
	for _, ifi := range mift {
		if err := r.LeaveGroup(ifi, &gaddr); err != nil {
			t.Fatal(err)
		}
	}
}
Ejemplo n.º 11
0
func main() {
	flag.Parse()

	c, err := net.ListenPacket(fmt.Sprintf("ip4:%d", *proto), "0.0.0.0")
	if err != nil {
		log.Fatal(err)
	}
	defer c.Close()
	p, err := ipv4.NewRawConn(c)
	if err != nil {
		log.Fatal(err)
	}
	p.SetControlMessage(ipv4.FlagTTL|ipv4.FlagSrc|ipv4.FlagDst|ipv4.FlagInterface, true)

	b := make([]byte, 8192)
	for {
		h, pp, cm, err := p.ReadFrom(b)
		if err != nil {
			log.Println(err)
			continue
		}
		log.Printf("%d bytes rcvd, %v, %v\n", len(pp), h, cm)
	}
}
Ejemplo n.º 12
0
func TestRawConnReadWriteUnicastICMP(t *testing.T) {
	switch runtime.GOOS {
	case "nacl", "plan9", "windows":
		t.Skipf("not supported on %s", runtime.GOOS)
	}
	if m, ok := nettest.SupportsRawIPSocket(); !ok {
		t.Skip(m)
	}
	ifi := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagLoopback)
	if ifi == nil {
		t.Skipf("not available on %s", runtime.GOOS)
	}

	c, err := net.ListenPacket("ip4:icmp", "0.0.0.0")
	if err != nil {
		t.Fatal(err)
	}
	defer c.Close()

	dst, err := net.ResolveIPAddr("ip4", "127.0.0.1")
	if err != nil {
		t.Fatal(err)
	}
	r, err := ipv4.NewRawConn(c)
	if err != nil {
		t.Fatal(err)
	}
	defer r.Close()
	cf := ipv4.FlagTTL | ipv4.FlagDst | ipv4.FlagInterface

	for i, toggle := range []bool{true, false, true} {
		wb, err := (&icmp.Message{
			Type: ipv4.ICMPTypeEcho, Code: 0,
			Body: &icmp.Echo{
				ID: os.Getpid() & 0xffff, Seq: i + 1,
				Data: []byte("HELLO-R-U-THERE"),
			},
		}).Marshal(nil)
		if err != nil {
			t.Fatal(err)
		}
		wh := &ipv4.Header{
			Version:  ipv4.Version,
			Len:      ipv4.HeaderLen,
			TOS:      i + 1,
			TotalLen: ipv4.HeaderLen + len(wb),
			TTL:      i + 1,
			Protocol: 1,
			Dst:      dst.IP,
		}
		if err := r.SetControlMessage(cf, toggle); err != nil {
			if nettest.ProtocolNotSupported(err) {
				t.Logf("not supported on %s", runtime.GOOS)
				continue
			}
			t.Fatal(err)
		}
		if err := r.SetWriteDeadline(time.Now().Add(100 * time.Millisecond)); err != nil {
			t.Fatal(err)
		}
		if err := r.WriteTo(wh, wb, nil); err != nil {
			t.Fatal(err)
		}
		rb := make([]byte, ipv4.HeaderLen+128)
	loop:
		if err := r.SetReadDeadline(time.Now().Add(100 * time.Millisecond)); err != nil {
			t.Fatal(err)
		}
		if _, b, _, err := r.ReadFrom(rb); err != nil {
			switch runtime.GOOS {
			case "darwin": // older darwin kernels have some limitation on receiving icmp packet through raw socket
				t.Logf("not supported on %s", runtime.GOOS)
				continue
			}
			t.Fatal(err)
		} else {
			m, err := icmp.ParseMessage(iana.ProtocolICMP, b)
			if err != nil {
				t.Fatal(err)
			}
			if runtime.GOOS == "linux" && m.Type == ipv4.ICMPTypeEcho {
				// On Linux we must handle own sent packets.
				goto loop
			}
			if m.Type != ipv4.ICMPTypeEchoReply || m.Code != 0 {
				t.Fatalf("got type=%v, code=%v; want type=%v, code=%v", m.Type, m.Code, ipv4.ICMPTypeEchoReply, 0)
			}
		}
	}
}
Ejemplo n.º 13
0
func TestRawConnReadWriteMulticastICMP(t *testing.T) {
	if testing.Short() {
		t.Skip("to avoid external network")
	}
	if m, ok := nettest.SupportsRawIPSocket(); !ok {
		t.Skip(m)
	}
	ifi := nettest.RoutedInterface("ip4", net.FlagUp|net.FlagMulticast|net.FlagLoopback)
	if ifi == nil {
		t.Skipf("not available on %s", runtime.GOOS)
	}

	for _, tt := range rawConnReadWriteMulticastICMPTests {
		c, err := net.ListenPacket("ip4:icmp", "0.0.0.0")
		if err != nil {
			t.Fatal(err)
		}
		defer c.Close()

		r, err := ipv4.NewRawConn(c)
		if err != nil {
			t.Fatal(err)
		}
		defer r.Close()
		if tt.src == nil {
			if err := r.JoinGroup(ifi, tt.grp); err != nil {
				t.Fatal(err)
			}
			defer r.LeaveGroup(ifi, tt.grp)
		} else {
			if err := r.JoinSourceSpecificGroup(ifi, tt.grp, tt.src); err != nil {
				switch runtime.GOOS {
				case "freebsd", "linux":
				default: // platforms that don't support IGMPv2/3 fail here
					t.Logf("not supported on %s", runtime.GOOS)
					continue
				}
				t.Fatal(err)
			}
			defer r.LeaveSourceSpecificGroup(ifi, tt.grp, tt.src)
		}
		if err := r.SetMulticastInterface(ifi); err != nil {
			t.Fatal(err)
		}
		if _, err := r.MulticastInterface(); err != nil {
			t.Fatal(err)
		}
		if err := r.SetMulticastLoopback(true); err != nil {
			t.Fatal(err)
		}
		if _, err := r.MulticastLoopback(); err != nil {
			t.Fatal(err)
		}
		cf := ipv4.FlagTTL | ipv4.FlagDst | ipv4.FlagInterface

		for i, toggle := range []bool{true, false, true} {
			wb, err := (&icmp.Message{
				Type: ipv4.ICMPTypeEcho, Code: 0,
				Body: &icmp.Echo{
					ID: os.Getpid() & 0xffff, Seq: i + 1,
					Data: []byte("HELLO-R-U-THERE"),
				},
			}).Marshal(nil)
			if err != nil {
				t.Fatal(err)
			}
			wh := &ipv4.Header{
				Version:  ipv4.Version,
				Len:      ipv4.HeaderLen,
				TOS:      i + 1,
				TotalLen: ipv4.HeaderLen + len(wb),
				Protocol: 1,
				Dst:      tt.grp.IP,
			}
			if err := r.SetControlMessage(cf, toggle); err != nil {
				if nettest.ProtocolNotSupported(err) {
					t.Logf("not supported on %s", runtime.GOOS)
					continue
				}
				t.Fatal(err)
			}
			if err := r.SetDeadline(time.Now().Add(200 * time.Millisecond)); err != nil {
				t.Fatal(err)
			}
			r.SetMulticastTTL(i + 1)
			if err := r.WriteTo(wh, wb, nil); err != nil {
				t.Fatal(err)
			}
			rb := make([]byte, ipv4.HeaderLen+128)
			if rh, b, _, err := r.ReadFrom(rb); err != nil {
				t.Fatal(err)
			} else {
				m, err := icmp.ParseMessage(iana.ProtocolICMP, b)
				if err != nil {
					t.Fatal(err)
				}
				switch {
				case (rh.Dst.IsLoopback() || rh.Dst.IsLinkLocalUnicast() || rh.Dst.IsGlobalUnicast()) && m.Type == ipv4.ICMPTypeEchoReply && m.Code == 0: // net.inet.icmp.bmcastecho=1
				case rh.Dst.IsMulticast() && m.Type == ipv4.ICMPTypeEcho && m.Code == 0: // net.inet.icmp.bmcastecho=0
				default:
					t.Fatalf("got type=%v, code=%v; want type=%v, code=%v", m.Type, m.Code, ipv4.ICMPTypeEchoReply, 0)
				}
			}
		}
	}
}
Ejemplo n.º 14
0
func (s *Server) ListenAndServeUDPv4() {
	ipAddr := &net.IPAddr{IP: net.IPv4zero}
	conn, err := net.ListenIP("ip4:udp", ipAddr)
	if err != nil {
		l.Info(err.Error())
		return
	}
	defer conn.Close()
	if err = bindToDevice(conn, "tap"+s.name); err != nil {
		l.Info(err.Error())
		return
	}

	s.Lock()
	s.ipv4conn, err = ipv4.NewRawConn(conn)
	s.Unlock()
	if err != nil {
		l.Info(err.Error())
		return
	}

	if err = s.ipv4conn.SetControlMessage(ipv4.FlagDst, true); err != nil {
		l.Warning(err.Error())
		return
	}

	buffer := make([]byte, 1500)

	var gw net.IP
	for _, addr := range s.metadata.Network.IP {
		if addr.Family == "ipv4" && addr.Host == "true" && addr.Gateway == "true" {
			gw = net.ParseIP(addr.Address)
		}
	}
	iface, err := net.InterfaceByName("tap" + s.name)
	if err != nil {
		l.Info(fmt.Sprintf("failed to get iface: %s", err.Error()))
		return
	}

	for {
		select {
		case <-s.done:
			return
		default:
			s.ipv4conn.SetReadDeadline(time.Now().Add(time.Second))
			hdr, _, _, err := s.ipv4conn.ReadFrom(buffer)
			if err != nil {
				switch v := err.(type) {
				case *net.OpError:
					if v.Timeout() {
						continue
					}
				case *net.AddrError:
					if v.Timeout() {
						continue
					}
				case *net.UnknownNetworkError:
					if v.Timeout() {
						continue
					}
				default:
					l.Warning(err.Error())
					return
				}
			}
			var ip4 layers.IPv4
			var udp layers.UDP
			var dhcp4req layers.DHCPv4
			parser := gopacket.NewDecodingLayerParser(layers.LayerTypeIPv4, &ip4, &udp, &dhcp4req)
			decoded := []gopacket.LayerType{}
			err = parser.DecodeLayers(buffer, &decoded)
			for _, layerType := range decoded {
				switch layerType {
				case layers.LayerTypeDHCPv4:
					if dhcp4req.Operation == layers.DHCP_MSG_REQ {
						dhcp4res, err := s.ServeUDPv4(&dhcp4req)
						if err != nil {
							l.Warning(err.Error())
							continue
						}
						if dhcp4res == nil {
							// ignore empty dhcp packets
							continue
						}

						buf := gopacket.NewSerializeBuffer()
						opts := gopacket.SerializeOptions{true, true}
						gopacket.SerializeLayers(buf, opts,
							&layers.UDP{SrcPort: 67, DstPort: 68},
							dhcp4res)

						wcm := ipv4.ControlMessage{TTL: 255}
						wcm.Dst = net.IPv4bcast.To4()
						wcm.Src = gw.To4()
						wcm.IfIndex = iface.Index
						err = s.ipv4conn.WriteTo(&ipv4.Header{Len: 20, TOS: hdr.TOS, TotalLen: 20 + int(len(buf.Bytes())), FragOff: 0, TTL: 255, Protocol: int(layers.IPProtocolUDP), Src: gw.To4(), Dst: net.IPv4bcast.To4()}, buf.Bytes(), &wcm)
						if err != nil {
							l.Warning(err.Error())
							continue
						}
					} else {
						continue
					}
				}
			}
		}
	}
}
Ejemplo n.º 15
0
//sendPacket generates & sends a packet of arbitrary size to a specific destination.
//The size specified should be larger then 40bytes.
func sendPacket(sourceIP string, destinationIP string, size int, message string, appID int, chanID int, icmpType layers.ICMPv4TypeCode) []byte {

	var payloadSize int
	if size < 28 {
		//Unable to create smaller packets.
		payloadSize = 0
	} else {
		payloadSize = size - 28
	}

	//Convert IP to 4bit representation
	srcIP := net.ParseIP(sourceIP).To4()
	dstIP := net.ParseIP(destinationIP).To4()

	//IP Layer
	ip := layers.IPv4{
		SrcIP:    srcIP,
		DstIP:    dstIP,
		Version:  4,
		TTL:      64,
		Protocol: layers.IPProtocolICMPv4,
	}

	icmp := layers.ICMPv4{
		TypeCode: icmpType,
	}

	opts := gopacket.SerializeOptions{
		FixLengths:       true,
		ComputeChecksums: true,
	}

	ipHeaderBuf := gopacket.NewSerializeBuffer()

	err := ip.SerializeTo(ipHeaderBuf, opts)
	if err != nil {
		panic(err)
	}

	//Set "Don't Fragment"-Flag in Header
	ipHeader, err := ipv4.ParseHeader(ipHeaderBuf.Bytes())
	ipHeader.Flags |= ipv4.DontFragment
	if err != nil {
		panic(err)
	}

	payloadBuf := gopacket.NewSerializeBuffer()

	//Influence the payload size
	payload := gopacket.Payload(generatePayload(payloadSize, ","+strconv.Itoa(appID)+","+strconv.Itoa(chanID)+","+message+","))
	err = gopacket.SerializeLayers(payloadBuf, opts, &icmp, payload)
	if err != nil {
		panic(err)
	}

	//Send packet
	var packetConn net.PacketConn
	var rawConn *ipv4.RawConn

	packetConn, err = net.ListenPacket("ip4:icmp", srcIP.String())
	if err != nil {
		panic(err)
	}
	rawConn, err = ipv4.NewRawConn(packetConn)
	if err != nil {
		panic(err)
	}

	err = rawConn.WriteTo(ipHeader, payloadBuf.Bytes(), nil)

	return append(ipHeaderBuf.Bytes(), payloadBuf.Bytes()...)
}