TUN-6666: Define packet package

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

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

@@ -0,0 +1,121 @@
+// Copyright 2016 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"
+)
+
+// Geneve is specifed here https://tools.ietf.org/html/draft-ietf-nvo3-geneve-03
+// Geneve Header:
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |Ver|  Opt Len  |O|C|    Rsvd.  |          Protocol Type        |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |        Virtual Network Identifier (VNI)       |    Reserved   |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |                    Variable Length Options                    |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+type Geneve struct {
+	BaseLayer
+	Version        uint8        // 2 bits
+	OptionsLength  uint8        // 6 bits
+	OAMPacket      bool         // 1 bits
+	CriticalOption bool         // 1 bits
+	Protocol       EthernetType // 16 bits
+	VNI            uint32       // 24bits
+	Options        []*GeneveOption
+}
+
+// Geneve Tunnel Options
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |          Option Class         |      Type     |R|R|R| Length  |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |                      Variable Option Data                     |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+type GeneveOption struct {
+	Class  uint16 // 16 bits
+	Type   uint8  // 8 bits
+	Flags  uint8  // 3 bits
+	Length uint8  // 5 bits
+	Data   []byte
+}
+
+// LayerType returns LayerTypeGeneve
+func (gn *Geneve) LayerType() gopacket.LayerType { return LayerTypeGeneve }
+
+func decodeGeneveOption(data []byte, gn *Geneve, df gopacket.DecodeFeedback) (*GeneveOption, uint8, error) {
+	if len(data) < 3 {
+		df.SetTruncated()
+		return nil, 0, errors.New("geneve option too small")
+	}
+	opt := &GeneveOption{}
+
+	opt.Class = binary.BigEndian.Uint16(data[0:2])
+	opt.Type = data[2]
+	opt.Flags = data[3] >> 4
+	opt.Length = (data[3]&0xf)*4 + 4
+
+	if len(data) < int(opt.Length) {
+		df.SetTruncated()
+		return nil, 0, errors.New("geneve option too small")
+	}
+	opt.Data = make([]byte, opt.Length-4)
+	copy(opt.Data, data[4:opt.Length])
+
+	return opt, opt.Length, nil
+}
+
+func (gn *Geneve) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
+	if len(data) < 7 {
+		df.SetTruncated()
+		return errors.New("geneve packet too short")
+	}
+
+	gn.Version = data[0] >> 7
+	gn.OptionsLength = (data[0] & 0x3f) * 4
+
+	gn.OAMPacket = data[1]&0x80 > 0
+	gn.CriticalOption = data[1]&0x40 > 0
+	gn.Protocol = EthernetType(binary.BigEndian.Uint16(data[2:4]))
+
+	var buf [4]byte
+	copy(buf[1:], data[4:7])
+	gn.VNI = binary.BigEndian.Uint32(buf[:])
+
+	offset, length := uint8(8), int32(gn.OptionsLength)
+	if len(data) < int(length+7) {
+		df.SetTruncated()
+		return errors.New("geneve packet too short")
+	}
+
+	for length > 0 {
+		opt, len, err := decodeGeneveOption(data[offset:], gn, df)
+		if err != nil {
+			return err
+		}
+		gn.Options = append(gn.Options, opt)
+
+		length -= int32(len)
+		offset += len
+	}
+
+	gn.BaseLayer = BaseLayer{data[:offset], data[offset:]}
+
+	return nil
+}
+
+func (gn *Geneve) NextLayerType() gopacket.LayerType {
+	return gn.Protocol.LayerType()
+}
+
+func decodeGeneve(data []byte, p gopacket.PacketBuilder) error {
+	gn := &Geneve{}
+	return decodingLayerDecoder(gn, data, p)
+}