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
7package layers
8
9import (
10	"encoding/binary"
11	"errors"
12	"fmt"
13	"net"
14
15	"github.com/google/gopacket"
16)
17
18type LinuxSLLPacketType uint16
19
20const (
21	LinuxSLLPacketTypeHost      LinuxSLLPacketType = 0 // To us
22	LinuxSLLPacketTypeBroadcast LinuxSLLPacketType = 1 // To all
23	LinuxSLLPacketTypeMulticast LinuxSLLPacketType = 2 // To group
24	LinuxSLLPacketTypeOtherhost LinuxSLLPacketType = 3 // To someone else
25	LinuxSLLPacketTypeOutgoing  LinuxSLLPacketType = 4 // Outgoing of any type
26	// These ones are invisible by user level
27	LinuxSLLPacketTypeLoopback  LinuxSLLPacketType = 5 // MC/BRD frame looped back
28	LinuxSLLPacketTypeFastroute LinuxSLLPacketType = 6 // Fastrouted frame
29)
30
31func (l LinuxSLLPacketType) String() string {
32	switch l {
33	case LinuxSLLPacketTypeHost:
34		return "host"
35	case LinuxSLLPacketTypeBroadcast:
36		return "broadcast"
37	case LinuxSLLPacketTypeMulticast:
38		return "multicast"
39	case LinuxSLLPacketTypeOtherhost:
40		return "otherhost"
41	case LinuxSLLPacketTypeOutgoing:
42		return "outgoing"
43	case LinuxSLLPacketTypeLoopback:
44		return "loopback"
45	case LinuxSLLPacketTypeFastroute:
46		return "fastroute"
47	}
48	return fmt.Sprintf("Unknown(%d)", int(l))
49}
50
51type LinuxSLL struct {
52	BaseLayer
53	PacketType   LinuxSLLPacketType
54	AddrLen      uint16
55	Addr         net.HardwareAddr
56	EthernetType EthernetType
57	AddrType     uint16
58}
59
60// LayerType returns LayerTypeLinuxSLL.
61func (sll *LinuxSLL) LayerType() gopacket.LayerType { return LayerTypeLinuxSLL }
62
63func (sll *LinuxSLL) CanDecode() gopacket.LayerClass {
64	return LayerTypeLinuxSLL
65}
66
67func (sll *LinuxSLL) LinkFlow() gopacket.Flow {
68	return gopacket.NewFlow(EndpointMAC, sll.Addr, nil)
69}
70
71func (sll *LinuxSLL) NextLayerType() gopacket.LayerType {
72	return sll.EthernetType.LayerType()
73}
74
75func (sll *LinuxSLL) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
76	if len(data) < 16 {
77		return errors.New("Linux SLL packet too small")
78	}
79	sll.PacketType = LinuxSLLPacketType(binary.BigEndian.Uint16(data[0:2]))
80	sll.AddrType = binary.BigEndian.Uint16(data[2:4])
81	sll.AddrLen = binary.BigEndian.Uint16(data[4:6])
82
83	sll.Addr = net.HardwareAddr(data[6 : sll.AddrLen+6])
84	sll.EthernetType = EthernetType(binary.BigEndian.Uint16(data[14:16]))
85	sll.BaseLayer = BaseLayer{data[:16], data[16:]}
86
87	return nil
88}
89
90func decodeLinuxSLL(data []byte, p gopacket.PacketBuilder) error {
91	sll := &LinuxSLL{}
92	if err := sll.DecodeFromBytes(data, p); err != nil {
93		return err
94	}
95	p.AddLayer(sll)
96	p.SetLinkLayer(sll)
97	return p.NextDecoder(sll.EthernetType)
98}
99