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

   1 // Copyright 2012 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         "github.com/google/gopacket"
  12 )
  13
  14 // PPPoE is the layer for PPPoE encapsulation headers.
  15 type PPPoE struct {
  16         BaseLayer
  17         Version   uint8
  18         Type      uint8
  19         Code      PPPoECode
  20         SessionId uint16
  21         Length    uint16
  22 }
  23
  24 // LayerType returns gopacket.LayerTypePPPoE.
  25 func (p *PPPoE) LayerType() gopacket.LayerType {
  26         return LayerTypePPPoE
  27 }
  28
  29 // decodePPPoE decodes the PPPoE header (see http://tools.ietf.org/html/rfc2516).
  30 func decodePPPoE(data []byte, p gopacket.PacketBuilder) error {
  31         pppoe := &PPPoE{
  32                 Version:   data[0] >> 4,
  33                 Type:      data[0] & 0x0F,
  34                 Code:      PPPoECode(data[1]),
  35                 SessionId: binary.BigEndian.Uint16(data[2:4]),
  36                 Length:    binary.BigEndian.Uint16(data[4:6]),
  37         }
  38         pppoe.BaseLayer = BaseLayer{data[:6], data[6 : 6+pppoe.Length]}
  39         p.AddLayer(pppoe)
  40         return p.NextDecoder(pppoe.Code)
  41 }
  42
  43 // SerializeTo writes the serialized form of this layer into the
  44 // SerializationBuffer, implementing gopacket.SerializableLayer.
  45 // See the docs for gopacket.SerializableLayer for more info.
  46 func (p *PPPoE) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
  47         payload := b.Bytes()
  48         bytes, err := b.PrependBytes(6)
  49         if err != nil {
  50                 return err
  51         }
  52         bytes[0] = (p.Version << 4) | p.Type
  53         bytes[1] = byte(p.Code)
  54         binary.BigEndian.PutUint16(bytes[2:], p.SessionId)
  55         if opts.FixLengths {
  56                 p.Length = uint16(len(payload))
  57         }
  58         binary.BigEndian.PutUint16(bytes[4:], p.Length)
  59         return nil
  60 }