diff --git a/vendor/github.com/google/gopacket/layers/tcp.go b/vendor/github.com/google/gopacket/layers/tcp.go
new file mode 100644
index 0000000..6b37f56
--- /dev/null
+++ b/vendor/github.com/google/gopacket/layers/tcp.go
@@ -0,0 +1,337 @@
+// Copyright 2012 Google, Inc. All rights reserved.
+// Copyright 2009-2011 Andreas Krennmair. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the LICENSE file in the root of the source
+// tree.
+
+package layers
+
+import (
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"fmt"
+
+	"github.com/google/gopacket"
+)
+
+// TCP is the layer for TCP headers.
+type TCP struct {
+	BaseLayer
+	SrcPort, DstPort                           TCPPort
+	Seq                                        uint32
+	Ack                                        uint32
+	DataOffset                                 uint8
+	FIN, SYN, RST, PSH, ACK, URG, ECE, CWR, NS bool
+	Window                                     uint16
+	Checksum                                   uint16
+	Urgent                                     uint16
+	sPort, dPort                               []byte
+	Options                                    []TCPOption
+	Padding                                    []byte
+	opts                                       [4]TCPOption
+	tcpipchecksum
+}
+
+// TCPOptionKind represents a TCP option code.
+type TCPOptionKind uint8
+
+const (
+	TCPOptionKindEndList                         = 0
+	TCPOptionKindNop                             = 1
+	TCPOptionKindMSS                             = 2  // len = 4
+	TCPOptionKindWindowScale                     = 3  // len = 3
+	TCPOptionKindSACKPermitted                   = 4  // len = 2
+	TCPOptionKindSACK                            = 5  // len = n
+	TCPOptionKindEcho                            = 6  // len = 6, obsolete
+	TCPOptionKindEchoReply                       = 7  // len = 6, obsolete
+	TCPOptionKindTimestamps                      = 8  // len = 10
+	TCPOptionKindPartialOrderConnectionPermitted = 9  // len = 2, obsolete
+	TCPOptionKindPartialOrderServiceProfile      = 10 // len = 3, obsolete
+	TCPOptionKindCC                              = 11 // obsolete
+	TCPOptionKindCCNew                           = 12 // obsolete
+	TCPOptionKindCCEcho                          = 13 // obsolete
+	TCPOptionKindAltChecksum                     = 14 // len = 3, obsolete
+	TCPOptionKindAltChecksumData                 = 15 // len = n, obsolete
+)
+
+func (k TCPOptionKind) String() string {
+	switch k {
+	case TCPOptionKindEndList:
+		return "EndList"
+	case TCPOptionKindNop:
+		return "NOP"
+	case TCPOptionKindMSS:
+		return "MSS"
+	case TCPOptionKindWindowScale:
+		return "WindowScale"
+	case TCPOptionKindSACKPermitted:
+		return "SACKPermitted"
+	case TCPOptionKindSACK:
+		return "SACK"
+	case TCPOptionKindEcho:
+		return "Echo"
+	case TCPOptionKindEchoReply:
+		return "EchoReply"
+	case TCPOptionKindTimestamps:
+		return "Timestamps"
+	case TCPOptionKindPartialOrderConnectionPermitted:
+		return "PartialOrderConnectionPermitted"
+	case TCPOptionKindPartialOrderServiceProfile:
+		return "PartialOrderServiceProfile"
+	case TCPOptionKindCC:
+		return "CC"
+	case TCPOptionKindCCNew:
+		return "CCNew"
+	case TCPOptionKindCCEcho:
+		return "CCEcho"
+	case TCPOptionKindAltChecksum:
+		return "AltChecksum"
+	case TCPOptionKindAltChecksumData:
+		return "AltChecksumData"
+	default:
+		return fmt.Sprintf("Unknown(%d)", k)
+	}
+}
+
+type TCPOption struct {
+	OptionType   TCPOptionKind
+	OptionLength uint8
+	OptionData   []byte
+}
+
+func (t TCPOption) String() string {
+	hd := hex.EncodeToString(t.OptionData)
+	if len(hd) > 0 {
+		hd = " 0x" + hd
+	}
+	switch t.OptionType {
+	case TCPOptionKindMSS:
+		return fmt.Sprintf("TCPOption(%s:%v%s)",
+			t.OptionType,
+			binary.BigEndian.Uint16(t.OptionData),
+			hd)
+
+	case TCPOptionKindTimestamps:
+		if len(t.OptionData) == 8 {
+			return fmt.Sprintf("TCPOption(%s:%v/%v%s)",
+				t.OptionType,
+				binary.BigEndian.Uint32(t.OptionData[:4]),
+				binary.BigEndian.Uint32(t.OptionData[4:8]),
+				hd)
+		}
+	}
+	return fmt.Sprintf("TCPOption(%s:%s)", t.OptionType, hd)
+}
+
+// LayerType returns gopacket.LayerTypeTCP
+func (t *TCP) LayerType() gopacket.LayerType { return LayerTypeTCP }
+
+// SerializeTo writes the serialized form of this layer into the
+// SerializationBuffer, implementing gopacket.SerializableLayer.
+// See the docs for gopacket.SerializableLayer for more info.
+func (t *TCP) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
+	var optionLength int
+	for _, o := range t.Options {
+		switch o.OptionType {
+		case 0, 1:
+			optionLength += 1
+		default:
+			optionLength += 2 + len(o.OptionData)
+		}
+	}
+	if opts.FixLengths {
+		if rem := optionLength % 4; rem != 0 {
+			t.Padding = lotsOfZeros[:4-rem]
+		}
+		t.DataOffset = uint8((len(t.Padding) + optionLength + 20) / 4)
+	}
+	bytes, err := b.PrependBytes(20 + optionLength + len(t.Padding))
+	if err != nil {
+		return err
+	}
+	binary.BigEndian.PutUint16(bytes, uint16(t.SrcPort))
+	binary.BigEndian.PutUint16(bytes[2:], uint16(t.DstPort))
+	binary.BigEndian.PutUint32(bytes[4:], t.Seq)
+	binary.BigEndian.PutUint32(bytes[8:], t.Ack)
+	binary.BigEndian.PutUint16(bytes[12:], t.flagsAndOffset())
+	binary.BigEndian.PutUint16(bytes[14:], t.Window)
+	binary.BigEndian.PutUint16(bytes[18:], t.Urgent)
+	start := 20
+	for _, o := range t.Options {
+		bytes[start] = byte(o.OptionType)
+		switch o.OptionType {
+		case 0, 1:
+			start++
+		default:
+			if opts.FixLengths {
+				o.OptionLength = uint8(len(o.OptionData) + 2)
+			}
+			bytes[start+1] = o.OptionLength
+			copy(bytes[start+2:start+len(o.OptionData)+2], o.OptionData)
+			start += len(o.OptionData) + 2
+		}
+	}
+	copy(bytes[start:], t.Padding)
+	if opts.ComputeChecksums {
+		// zero out checksum bytes in current serialization.
+		bytes[16] = 0
+		bytes[17] = 0
+		csum, err := t.computeChecksum(b.Bytes(), IPProtocolTCP)
+		if err != nil {
+			return err
+		}
+		t.Checksum = csum
+	}
+	binary.BigEndian.PutUint16(bytes[16:], t.Checksum)
+	return nil
+}
+
+func (t *TCP) ComputeChecksum() (uint16, error) {
+	return t.computeChecksum(append(t.Contents, t.Payload...), IPProtocolTCP)
+}
+
+func (t *TCP) flagsAndOffset() uint16 {
+	f := uint16(t.DataOffset) << 12
+	if t.FIN {
+		f |= 0x0001
+	}
+	if t.SYN {
+		f |= 0x0002
+	}
+	if t.RST {
+		f |= 0x0004
+	}
+	if t.PSH {
+		f |= 0x0008
+	}
+	if t.ACK {
+		f |= 0x0010
+	}
+	if t.URG {
+		f |= 0x0020
+	}
+	if t.ECE {
+		f |= 0x0040
+	}
+	if t.CWR {
+		f |= 0x0080
+	}
+	if t.NS {
+		f |= 0x0100
+	}
+	return f
+}
+
+func (tcp *TCP) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
+	if len(data) < 20 {
+		df.SetTruncated()
+		return fmt.Errorf("Invalid TCP header. Length %d less than 20", len(data))
+	}
+	tcp.SrcPort = TCPPort(binary.BigEndian.Uint16(data[0:2]))
+	tcp.sPort = data[0:2]
+	tcp.DstPort = TCPPort(binary.BigEndian.Uint16(data[2:4]))
+	tcp.dPort = data[2:4]
+	tcp.Seq = binary.BigEndian.Uint32(data[4:8])
+	tcp.Ack = binary.BigEndian.Uint32(data[8:12])
+	tcp.DataOffset = data[12] >> 4
+	tcp.FIN = data[13]&0x01 != 0
+	tcp.SYN = data[13]&0x02 != 0
+	tcp.RST = data[13]&0x04 != 0
+	tcp.PSH = data[13]&0x08 != 0
+	tcp.ACK = data[13]&0x10 != 0
+	tcp.URG = data[13]&0x20 != 0
+	tcp.ECE = data[13]&0x40 != 0
+	tcp.CWR = data[13]&0x80 != 0
+	tcp.NS = data[12]&0x01 != 0
+	tcp.Window = binary.BigEndian.Uint16(data[14:16])
+	tcp.Checksum = binary.BigEndian.Uint16(data[16:18])
+	tcp.Urgent = binary.BigEndian.Uint16(data[18:20])
+	if tcp.Options == nil {
+		// Pre-allocate to avoid allocating a slice.
+		tcp.Options = tcp.opts[:0]
+	} else {
+		tcp.Options = tcp.Options[:0]
+	}
+	if tcp.DataOffset < 5 {
+		return fmt.Errorf("Invalid TCP data offset %d < 5", tcp.DataOffset)
+	}
+	dataStart := int(tcp.DataOffset) * 4
+	if dataStart > len(data) {
+		df.SetTruncated()
+		tcp.Payload = nil
+		tcp.Contents = data
+		return errors.New("TCP data offset greater than packet length")
+	}
+	tcp.Contents = data[:dataStart]
+	tcp.Payload = data[dataStart:]
+	// From here on, data points just to the header options.
+	data = data[20:dataStart]
+	for len(data) > 0 {
+		tcp.Options = append(tcp.Options, TCPOption{OptionType: TCPOptionKind(data[0])})
+		opt := &tcp.Options[len(tcp.Options)-1]
+		switch opt.OptionType {
+		case TCPOptionKindEndList: // End of options
+			opt.OptionLength = 1
+			tcp.Padding = data[1:]
+			break
+		case TCPOptionKindNop: // 1 byte padding
+			opt.OptionLength = 1
+		default:
+			if len(data) < 2 {
+				df.SetTruncated()
+				return fmt.Errorf("Invalid TCP option length. Length %d less than 2", len(data))
+			}
+			opt.OptionLength = data[1]
+			if opt.OptionLength < 2 {
+				return fmt.Errorf("Invalid TCP option length %d < 2", opt.OptionLength)
+			} else if int(opt.OptionLength) > len(data) {
+				df.SetTruncated()
+				return fmt.Errorf("Invalid TCP option length %d exceeds remaining %d bytes", opt.OptionLength, len(data))
+			}
+			opt.OptionData = data[2:opt.OptionLength]
+		}
+		data = data[opt.OptionLength:]
+	}
+	return nil
+}
+
+func (t *TCP) CanDecode() gopacket.LayerClass {
+	return LayerTypeTCP
+}
+
+func (t *TCP) NextLayerType() gopacket.LayerType {
+	lt := t.DstPort.LayerType()
+	if lt == gopacket.LayerTypePayload {
+		lt = t.SrcPort.LayerType()
+	}
+	return lt
+}
+
+func decodeTCP(data []byte, p gopacket.PacketBuilder) error {
+	tcp := &TCP{}
+	err := tcp.DecodeFromBytes(data, p)
+	p.AddLayer(tcp)
+	p.SetTransportLayer(tcp)
+	if err != nil {
+		return err
+	}
+	if p.DecodeOptions().DecodeStreamsAsDatagrams {
+		return p.NextDecoder(tcp.NextLayerType())
+	} else {
+		return p.NextDecoder(gopacket.LayerTypePayload)
+	}
+}
+
+func (t *TCP) TransportFlow() gopacket.Flow {
+	return gopacket.NewFlow(EndpointTCPPort, t.sPort, t.dPort)
+}
+
+// For testing only
+func (t *TCP) SetInternalPortsForTesting() {
+	t.sPort = make([]byte, 2)
+	t.dPort = make([]byte, 2)
+	binary.BigEndian.PutUint16(t.sPort, uint16(t.SrcPort))
+	binary.BigEndian.PutUint16(t.dPort, uint16(t.DstPort))
+}