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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"
"errors"
"fmt"
"net"
"github.com/google/gopacket"
)
type LinuxSLLPacketType uint16
const (
LinuxSLLPacketTypeHost LinuxSLLPacketType = 0 // To us
LinuxSLLPacketTypeBroadcast LinuxSLLPacketType = 1 // To all
LinuxSLLPacketTypeMulticast LinuxSLLPacketType = 2 // To group
LinuxSLLPacketTypeOtherhost LinuxSLLPacketType = 3 // To someone else
LinuxSLLPacketTypeOutgoing LinuxSLLPacketType = 4 // Outgoing of any type
// These ones are invisible by user level
LinuxSLLPacketTypeLoopback LinuxSLLPacketType = 5 // MC/BRD frame looped back
LinuxSLLPacketTypeFastroute LinuxSLLPacketType = 6 // Fastrouted frame
)
func (l LinuxSLLPacketType) String() string {
switch l {
case LinuxSLLPacketTypeHost:
return "host"
case LinuxSLLPacketTypeBroadcast:
return "broadcast"
case LinuxSLLPacketTypeMulticast:
return "multicast"
case LinuxSLLPacketTypeOtherhost:
return "otherhost"
case LinuxSLLPacketTypeOutgoing:
return "outgoing"
case LinuxSLLPacketTypeLoopback:
return "loopback"
case LinuxSLLPacketTypeFastroute:
return "fastroute"
}
return fmt.Sprintf("Unknown(%d)", int(l))
}
type LinuxSLL struct {
BaseLayer
PacketType LinuxSLLPacketType
AddrLen uint16
Addr net.HardwareAddr
EthernetType EthernetType
}
// LayerType returns LayerTypeLinuxSLL.
func (sll *LinuxSLL) LayerType() gopacket.LayerType { return LayerTypeLinuxSLL }
func (sll *LinuxSLL) CanDecode() gopacket.LayerClass {
return LayerTypeLinuxSLL
}
func (sll *LinuxSLL) LinkFlow() gopacket.Flow {
return gopacket.NewFlow(EndpointMAC, sll.Addr, nil)
}
func (sll *LinuxSLL) NextLayerType() gopacket.LayerType {
return sll.EthernetType.LayerType()
}
func (sll *LinuxSLL) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
if len(data) < 16 {
return errors.New("Linux SLL packet too small")
}
sll.PacketType = LinuxSLLPacketType(binary.BigEndian.Uint16(data[0:2]))
sll.AddrLen = binary.BigEndian.Uint16(data[4:6])
sll.Addr = net.HardwareAddr(data[6 : sll.AddrLen+6])
sll.EthernetType = EthernetType(binary.BigEndian.Uint16(data[14:16]))
sll.BaseLayer = BaseLayer{data[:16], data[16:]}
return nil
}
func decodeLinuxSLL(data []byte, p gopacket.PacketBuilder) error {
sll := &LinuxSLL{}
if err := sll.DecodeFromBytes(data, p); err != nil {
return err
}
p.AddLayer(sll)
p.SetLinkLayer(sll)
return p.NextDecoder(sll.EthernetType)
}