Matteo Scandolo | 4b3fc7e | 2019-09-17 16:49:54 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2018-present Open Networking Foundation |
| 3 | |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package packetHandlers |
| 18 | |
| 19 | import ( |
| 20 | "errors" |
| 21 | "github.com/google/gopacket" |
| 22 | "github.com/google/gopacket/layers" |
| 23 | ) |
| 24 | |
| 25 | func PushSingleTag(tag int, pkt gopacket.Packet) (gopacket.Packet, error) { |
| 26 | // TODO can this method be semplified? |
| 27 | if eth := getEthernetLayer(pkt); eth != nil { |
| 28 | ethernetLayer := &layers.Ethernet{ |
| 29 | SrcMAC: eth.SrcMAC, |
| 30 | DstMAC: eth.DstMAC, |
| 31 | EthernetType: 0x8100, |
| 32 | } |
| 33 | |
| 34 | dot1qLayer := &layers.Dot1Q{ |
| 35 | Type: eth.EthernetType, |
| 36 | VLANIdentifier: uint16(tag), |
| 37 | } |
| 38 | |
| 39 | buffer := gopacket.NewSerializeBuffer() |
| 40 | gopacket.SerializeLayers( |
| 41 | buffer, |
| 42 | gopacket.SerializeOptions{ |
| 43 | FixLengths: false, |
| 44 | }, |
| 45 | ethernetLayer, |
| 46 | dot1qLayer, |
| 47 | gopacket.Payload(eth.Payload), |
| 48 | ) |
| 49 | ret := gopacket.NewPacket( |
| 50 | buffer.Bytes(), |
| 51 | layers.LayerTypeEthernet, |
| 52 | gopacket.Default, |
| 53 | ) |
| 54 | |
| 55 | return ret, nil |
| 56 | } |
| 57 | return nil, errors.New("Couldn't extract LayerTypeEthernet from packet") |
| 58 | } |
| 59 | |
| 60 | func PopSingleTag(pkt gopacket.Packet) (gopacket.Packet, error) { |
| 61 | layer, err := getDot1QLayer(pkt) |
| 62 | if err != nil { |
| 63 | return nil, err |
| 64 | } |
| 65 | |
| 66 | if eth := getEthernetLayer(pkt); eth != nil { |
| 67 | ethernetLayer := &layers.Ethernet{ |
| 68 | SrcMAC: eth.SrcMAC, |
| 69 | DstMAC: eth.DstMAC, |
| 70 | EthernetType: layer.Type, |
| 71 | } |
| 72 | buffer := gopacket.NewSerializeBuffer() |
| 73 | gopacket.SerializeLayers(buffer, gopacket.SerializeOptions{}, |
| 74 | ethernetLayer, |
| 75 | gopacket.Payload(layer.Payload), |
| 76 | ) |
| 77 | retpkt := gopacket.NewPacket( |
| 78 | buffer.Bytes(), |
| 79 | layers.LayerTypeEthernet, |
| 80 | gopacket.Default, |
| 81 | ) |
| 82 | |
| 83 | return retpkt, nil |
| 84 | } |
| 85 | return nil, errors.New("no-ethernet-layer") |
| 86 | } |
| 87 | |
| 88 | func PopDoubleTag(pkt gopacket.Packet) (gopacket.Packet, error) { |
| 89 | packet, err := PopSingleTag(pkt) |
| 90 | if err != nil { |
| 91 | return nil, err |
| 92 | } |
| 93 | packet, err = PopSingleTag(packet) |
| 94 | if err != nil { |
| 95 | return nil, err |
| 96 | } |
| 97 | return packet, nil |
| 98 | } |
| 99 | |
| 100 | func getEthernetLayer(pkt gopacket.Packet) *layers.Ethernet { |
| 101 | eth := &layers.Ethernet{} |
| 102 | if ethLayer := pkt.Layer(layers.LayerTypeEthernet); ethLayer != nil { |
| 103 | eth, _ = ethLayer.(*layers.Ethernet) |
| 104 | } |
| 105 | return eth |
| 106 | } |
| 107 | |
| 108 | func getDot1QLayer(pkt gopacket.Packet) (*layers.Dot1Q, error) { |
| 109 | dot1q := &layers.Dot1Q{} |
| 110 | if dot1qLayer := pkt.Layer(layers.LayerTypeDot1Q); dot1qLayer != nil { |
| 111 | dot1q = dot1qLayer.(*layers.Dot1Q) |
| 112 | return dot1q, nil |
| 113 | } |
| 114 | return nil, errors.New("no-dot1q-layer-in-packet") |
| 115 | } |
| 116 | |
| 117 | func getVlanTag(pkt gopacket.Packet) (uint16, error) { |
| 118 | dot1q, err := getDot1QLayer(pkt) |
| 119 | if err != nil { |
| 120 | return 0, err |
| 121 | } |
| 122 | return dot1q.VLANIdentifier, nil |
| 123 | } |