TUN-6666: Define packet package

This package defines IP and ICMP packet, decoders, encoder and flow

vendor/github.com/google/gopacket/layers/ppp.go

@@ -0,0 +1,88 @@
+// Copyright 2012 Google, Inc. 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"
+	"errors"
+	"github.com/google/gopacket"
+)
+
+// PPP is the layer for PPP encapsulation headers.
+type PPP struct {
+	BaseLayer
+	PPPType       PPPType
+	HasPPTPHeader bool
+}
+
+// PPPEndpoint is a singleton endpoint for PPP.  Since there is no actual
+// addressing for the two ends of a PPP connection, we use a singleton value
+// named 'point' for each endpoint.
+var PPPEndpoint = gopacket.NewEndpoint(EndpointPPP, nil)
+
+// PPPFlow is a singleton flow for PPP.  Since there is no actual addressing for
+// the two ends of a PPP connection, we use a singleton value to represent the
+// flow for all PPP connections.
+var PPPFlow = gopacket.NewFlow(EndpointPPP, nil, nil)
+
+// LayerType returns LayerTypePPP
+func (p *PPP) LayerType() gopacket.LayerType { return LayerTypePPP }
+
+// LinkFlow returns PPPFlow.
+func (p *PPP) LinkFlow() gopacket.Flow { return PPPFlow }
+
+func decodePPP(data []byte, p gopacket.PacketBuilder) error {
+	ppp := &PPP{}
+	offset := 0
+	if data[0] == 0xff && data[1] == 0x03 {
+		offset = 2
+		ppp.HasPPTPHeader = true
+	}
+	if data[offset]&0x1 == 0 {
+		if data[offset+1]&0x1 == 0 {
+			return errors.New("PPP has invalid type")
+		}
+		ppp.PPPType = PPPType(binary.BigEndian.Uint16(data[offset : offset+2]))
+		ppp.Contents = data[offset : offset+2]
+		ppp.Payload = data[offset+2:]
+	} else {
+		ppp.PPPType = PPPType(data[offset])
+		ppp.Contents = data[offset : offset+1]
+		ppp.Payload = data[offset+1:]
+	}
+	p.AddLayer(ppp)
+	p.SetLinkLayer(ppp)
+	return p.NextDecoder(ppp.PPPType)
+}
+
+// SerializeTo writes the serialized form of this layer into the
+// SerializationBuffer, implementing gopacket.SerializableLayer.
+// See the docs for gopacket.SerializableLayer for more info.
+func (p *PPP) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
+	if p.PPPType&0x100 == 0 {
+		bytes, err := b.PrependBytes(2)
+		if err != nil {
+			return err
+		}
+		binary.BigEndian.PutUint16(bytes, uint16(p.PPPType))
+	} else {
+		bytes, err := b.PrependBytes(1)
+		if err != nil {
+			return err
+		}
+		bytes[0] = uint8(p.PPPType)
+	}
+	if p.HasPPTPHeader {
+		bytes, err := b.PrependBytes(2)
+		if err != nil {
+			return err
+		}
+		bytes[0] = 0xff
+		bytes[1] = 0x03
+	}
+	return nil
+}