TUN-6666: Define packet package

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

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

@@ -0,0 +1,118 @@
+// 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"
+	"errors"
+	"fmt"
+
+	"github.com/google/gopacket"
+)
+
+// Potential values for ARP.Operation.
+const (
+	ARPRequest = 1
+	ARPReply   = 2
+)
+
+// ARP is a ARP packet header.
+type ARP struct {
+	BaseLayer
+	AddrType          LinkType
+	Protocol          EthernetType
+	HwAddressSize     uint8
+	ProtAddressSize   uint8
+	Operation         uint16
+	SourceHwAddress   []byte
+	SourceProtAddress []byte
+	DstHwAddress      []byte
+	DstProtAddress    []byte
+}
+
+// LayerType returns LayerTypeARP
+func (arp *ARP) LayerType() gopacket.LayerType { return LayerTypeARP }
+
+// DecodeFromBytes decodes the given bytes into this layer.
+func (arp *ARP) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
+	if len(data) < 8 {
+		df.SetTruncated()
+		return fmt.Errorf("ARP length %d too short", len(data))
+	}
+	arp.AddrType = LinkType(binary.BigEndian.Uint16(data[0:2]))
+	arp.Protocol = EthernetType(binary.BigEndian.Uint16(data[2:4]))
+	arp.HwAddressSize = data[4]
+	arp.ProtAddressSize = data[5]
+	arp.Operation = binary.BigEndian.Uint16(data[6:8])
+	arpLength := 8 + 2*arp.HwAddressSize + 2*arp.ProtAddressSize
+	if len(data) < int(arpLength) {
+		df.SetTruncated()
+		return fmt.Errorf("ARP length %d too short, %d expected", len(data), arpLength)
+	}
+	arp.SourceHwAddress = data[8 : 8+arp.HwAddressSize]
+	arp.SourceProtAddress = data[8+arp.HwAddressSize : 8+arp.HwAddressSize+arp.ProtAddressSize]
+	arp.DstHwAddress = data[8+arp.HwAddressSize+arp.ProtAddressSize : 8+2*arp.HwAddressSize+arp.ProtAddressSize]
+	arp.DstProtAddress = data[8+2*arp.HwAddressSize+arp.ProtAddressSize : 8+2*arp.HwAddressSize+2*arp.ProtAddressSize]
+
+	arp.Contents = data[:arpLength]
+	arp.Payload = data[arpLength:]
+	return nil
+}
+
+// SerializeTo writes the serialized form of this layer into the
+// SerializationBuffer, implementing gopacket.SerializableLayer.
+// See the docs for gopacket.SerializableLayer for more info.
+func (arp *ARP) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
+	size := 8 + len(arp.SourceHwAddress) + len(arp.SourceProtAddress) + len(arp.DstHwAddress) + len(arp.DstProtAddress)
+	bytes, err := b.PrependBytes(size)
+	if err != nil {
+		return err
+	}
+	if opts.FixLengths {
+		if len(arp.SourceHwAddress) != len(arp.DstHwAddress) {
+			return errors.New("mismatched hardware address sizes")
+		}
+		arp.HwAddressSize = uint8(len(arp.SourceHwAddress))
+		if len(arp.SourceProtAddress) != len(arp.DstProtAddress) {
+			return errors.New("mismatched prot address sizes")
+		}
+		arp.ProtAddressSize = uint8(len(arp.SourceProtAddress))
+	}
+	binary.BigEndian.PutUint16(bytes, uint16(arp.AddrType))
+	binary.BigEndian.PutUint16(bytes[2:], uint16(arp.Protocol))
+	bytes[4] = arp.HwAddressSize
+	bytes[5] = arp.ProtAddressSize
+	binary.BigEndian.PutUint16(bytes[6:], arp.Operation)
+	start := 8
+	for _, addr := range [][]byte{
+		arp.SourceHwAddress,
+		arp.SourceProtAddress,
+		arp.DstHwAddress,
+		arp.DstProtAddress,
+	} {
+		copy(bytes[start:], addr)
+		start += len(addr)
+	}
+	return nil
+}
+
+// CanDecode returns the set of layer types that this DecodingLayer can decode.
+func (arp *ARP) CanDecode() gopacket.LayerClass {
+	return LayerTypeARP
+}
+
+// NextLayerType returns the layer type contained by this DecodingLayer.
+func (arp *ARP) NextLayerType() gopacket.LayerType {
+	return gopacket.LayerTypePayload
+}
+
+func decodeARP(data []byte, p gopacket.PacketBuilder) error {
+
+	arp := &ARP{}
+	return decodingLayerDecoder(arp, data, p)
+}