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// Copyright 2012 Google, Inc. 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"
"github.com/google/gopacket"
)
// PPPoE is the layer for PPPoE encapsulation headers.
type PPPoE struct {
BaseLayer
Version uint8
Type uint8
Code PPPoECode
SessionId uint16
Length uint16
}
// LayerType returns gopacket.LayerTypePPPoE.
func (p *PPPoE) LayerType() gopacket.LayerType {
return LayerTypePPPoE
}
// decodePPPoE decodes the PPPoE header (see http://tools.ietf.org/html/rfc2516).
func decodePPPoE(data []byte, p gopacket.PacketBuilder) error {
pppoe := &PPPoE{
Version: data[0] >> 4,
Type: data[0] & 0x0F,
Code: PPPoECode(data[1]),
SessionId: binary.BigEndian.Uint16(data[2:4]),
Length: binary.BigEndian.Uint16(data[4:6]),
}
pppoe.BaseLayer = BaseLayer{data[:6], data[6 : 6+pppoe.Length]}
p.AddLayer(pppoe)
return p.NextDecoder(pppoe.Code)
}
// SerializeTo writes the serialized form of this layer into the
// SerializationBuffer, implementing gopacket.SerializableLayer.
// See the docs for gopacket.SerializableLayer for more info.
func (p *PPPoE) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
payload := b.Bytes()
bytes, err := b.PrependBytes(6)
if err != nil {
return err
}
bytes[0] = (p.Version << 4) | p.Type
bytes[1] = byte(p.Code)
binary.BigEndian.PutUint16(bytes[2:], p.SessionId)
if opts.FixLengths {
p.Length = uint16(len(payload))
}
binary.BigEndian.PutUint16(bytes[4:], p.Length)
return nil
}
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