87 lines
2.8 KiB
Go
87 lines
2.8 KiB
Go
// Copyright 2018 Google, Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the LICENSE file in the root of the source
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// tree.
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package layers
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import (
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"encoding/binary"
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"github.com/google/gopacket"
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)
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const (
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//ERSPANIIVersionObsolete - The obsolete value for the version field
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ERSPANIIVersionObsolete = 0x0
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// ERSPANIIVersion - The current value for the version field
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ERSPANIIVersion = 0x1
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)
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// ERSPANII contains all of the fields found in an ERSPAN Type II header
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// https://tools.ietf.org/html/draft-foschiano-erspan-03
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type ERSPANII struct {
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BaseLayer
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IsTruncated bool
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Version, CoS, TrunkEncap uint8
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VLANIdentifier, SessionID, Reserved uint16
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Index uint32
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}
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func (erspan2 *ERSPANII) LayerType() gopacket.LayerType { return LayerTypeERSPANII }
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// DecodeFromBytes decodes the given bytes into this layer.
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func (erspan2 *ERSPANII) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
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erspan2Length := 8
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erspan2.Version = data[0] & 0xF0 >> 4
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erspan2.VLANIdentifier = binary.BigEndian.Uint16(data[:2]) & 0x0FFF
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erspan2.CoS = data[2] & 0xE0 >> 5
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erspan2.TrunkEncap = data[2] & 0x18 >> 3
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erspan2.IsTruncated = data[2]&0x4>>2 != 0
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erspan2.SessionID = binary.BigEndian.Uint16(data[2:4]) & 0x03FF
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erspan2.Reserved = binary.BigEndian.Uint16(data[4:6]) & 0xFFF0 >> 4
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erspan2.Index = binary.BigEndian.Uint32(data[4:8]) & 0x000FFFFF
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erspan2.Contents = data[:erspan2Length]
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erspan2.Payload = data[erspan2Length:]
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return nil
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}
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// SerializeTo writes the serialized form of this layer into the
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// SerializationBuffer, implementing gopacket.SerializableLayer.
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// See the docs for gopacket.SerializableLayer for more info.
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func (erspan2 *ERSPANII) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
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bytes, err := b.PrependBytes(8)
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if err != nil {
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return err
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}
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twoByteInt := uint16(erspan2.Version&0xF)<<12 | erspan2.VLANIdentifier&0x0FFF
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binary.BigEndian.PutUint16(bytes, twoByteInt)
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twoByteInt = uint16(erspan2.CoS&0x7)<<13 | uint16(erspan2.TrunkEncap&0x3)<<11 | erspan2.SessionID&0x03FF
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if erspan2.IsTruncated {
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twoByteInt |= 0x400
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}
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binary.BigEndian.PutUint16(bytes[2:], twoByteInt)
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fourByteInt := uint32(erspan2.Reserved&0x0FFF)<<20 | erspan2.Index&0x000FFFFF
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binary.BigEndian.PutUint32(bytes[4:], fourByteInt)
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return nil
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}
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// CanDecode returns the set of layer types that this DecodingLayer can decode.
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func (erspan2 *ERSPANII) CanDecode() gopacket.LayerClass {
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return LayerTypeERSPANII
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}
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// NextLayerType returns the layer type contained by this DecodingLayer.
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func (erspan2 *ERSPANII) NextLayerType() gopacket.LayerType {
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return LayerTypeEthernet
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}
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func decodeERSPANII(data []byte, p gopacket.PacketBuilder) error {
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erspan2 := &ERSPANII{}
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return decodingLayerDecoder(erspan2, data, p)
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}
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