| Naveen Sampath | 04696f7 | 2022-06-13 15:19:14 +0530 | [diff] [blame] | 1 | // Copyright 2018 Google, Inc. All rights reserved. |
| 2 | // |
| 3 | // Use of this source code is governed by a BSD-style license |
| 4 | // that can be found in the LICENSE file in the root of the source |
| 5 | // tree. |
| 6 | |
| 7 | package layers |
| 8 | |
| 9 | import ( |
| 10 | "encoding/binary" |
| 11 | |
| 12 | "github.com/google/gopacket" |
| 13 | ) |
| 14 | |
| 15 | const ( |
| 16 | //ERSPANIIVersionObsolete - The obsolete value for the version field |
| 17 | ERSPANIIVersionObsolete = 0x0 |
| 18 | // ERSPANIIVersion - The current value for the version field |
| 19 | ERSPANIIVersion = 0x1 |
| 20 | ) |
| 21 | |
| 22 | // ERSPANII contains all of the fields found in an ERSPAN Type II header |
| 23 | // https://tools.ietf.org/html/draft-foschiano-erspan-03 |
| 24 | type ERSPANII struct { |
| 25 | BaseLayer |
| 26 | IsTruncated bool |
| 27 | Version, CoS, TrunkEncap uint8 |
| 28 | VLANIdentifier, SessionID, Reserved uint16 |
| 29 | Index uint32 |
| 30 | } |
| 31 | |
| 32 | func (erspan2 *ERSPANII) LayerType() gopacket.LayerType { return LayerTypeERSPANII } |
| 33 | |
| 34 | // DecodeFromBytes decodes the given bytes into this layer. |
| 35 | func (erspan2 *ERSPANII) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error { |
| 36 | erspan2Length := 8 |
| 37 | erspan2.Version = data[0] & 0xF0 >> 4 |
| 38 | erspan2.VLANIdentifier = binary.BigEndian.Uint16(data[:2]) & 0x0FFF |
| 39 | erspan2.CoS = data[2] & 0xE0 >> 5 |
| 40 | erspan2.TrunkEncap = data[2] & 0x18 >> 3 |
| 41 | erspan2.IsTruncated = data[2]&0x4>>2 != 0 |
| 42 | erspan2.SessionID = binary.BigEndian.Uint16(data[2:4]) & 0x03FF |
| 43 | erspan2.Reserved = binary.BigEndian.Uint16(data[4:6]) & 0xFFF0 >> 4 |
| 44 | erspan2.Index = binary.BigEndian.Uint32(data[4:8]) & 0x000FFFFF |
| 45 | erspan2.Contents = data[:erspan2Length] |
| 46 | erspan2.Payload = data[erspan2Length:] |
| 47 | return nil |
| 48 | } |
| 49 | |
| 50 | // SerializeTo writes the serialized form of this layer into the |
| 51 | // SerializationBuffer, implementing gopacket.SerializableLayer. |
| 52 | // See the docs for gopacket.SerializableLayer for more info. |
| 53 | func (erspan2 *ERSPANII) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error { |
| 54 | bytes, err := b.PrependBytes(8) |
| 55 | if err != nil { |
| 56 | return err |
| 57 | } |
| 58 | |
| 59 | twoByteInt := uint16(erspan2.Version&0xF)<<12 | erspan2.VLANIdentifier&0x0FFF |
| 60 | binary.BigEndian.PutUint16(bytes, twoByteInt) |
| 61 | |
| 62 | twoByteInt = uint16(erspan2.CoS&0x7)<<13 | uint16(erspan2.TrunkEncap&0x3)<<11 | erspan2.SessionID&0x03FF |
| 63 | if erspan2.IsTruncated { |
| 64 | twoByteInt |= 0x400 |
| 65 | } |
| 66 | binary.BigEndian.PutUint16(bytes[2:], twoByteInt) |
| 67 | |
| 68 | fourByteInt := uint32(erspan2.Reserved&0x0FFF)<<20 | erspan2.Index&0x000FFFFF |
| 69 | binary.BigEndian.PutUint32(bytes[4:], fourByteInt) |
| 70 | return nil |
| 71 | } |
| 72 | |
| 73 | // CanDecode returns the set of layer types that this DecodingLayer can decode. |
| 74 | func (erspan2 *ERSPANII) CanDecode() gopacket.LayerClass { |
| 75 | return LayerTypeERSPANII |
| 76 | } |
| 77 | |
| 78 | // NextLayerType returns the layer type contained by this DecodingLayer. |
| 79 | func (erspan2 *ERSPANII) NextLayerType() gopacket.LayerType { |
| 80 | return LayerTypeEthernet |
| 81 | } |
| 82 | |
| 83 | func decodeERSPANII(data []byte, p gopacket.PacketBuilder) error { |
| 84 | erspan2 := &ERSPANII{} |
| 85 | return decodingLayerDecoder(erspan2, data, p) |
| 86 | } |