forked from posteo/go-agentx
-
Notifications
You must be signed in to change notification settings - Fork 0
/
variable.go
185 lines (167 loc) · 4.78 KB
/
variable.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
// Copyright 2018 The agentx authors
// Licensed under the LGPLv3 with static-linking exception.
// See LICENCE file for details.
package pdu
import (
"bytes"
"encoding/binary"
"fmt"
"net"
"time"
"github.com/Yamu-OSS/go-agentx/value"
)
// Variable defines the pdu varbind packet.
type Variable struct {
Type VariableType
Name ObjectIdentifier
Value interface{}
}
// Set sets the variable.
func (v *Variable) Set(oid value.OID, t VariableType, value interface{}) {
v.Name.SetIdentifier(oid)
v.Type = t
v.Value = value
}
// ByteSize returns the number of bytes, the binding would need in the encoded version.
func (v *Variable) ByteSize() int {
bytes, err := v.MarshalBinary()
if err != nil {
panic(err)
}
return len(bytes)
}
// MarshalBinary returns the pdu packet as a slice of bytes.
func (v *Variable) MarshalBinary() ([]byte, error) {
buffer := &bytes.Buffer{}
binary.Write(buffer, binary.LittleEndian, &v.Type)
buffer.WriteByte(0x00)
buffer.WriteByte(0x00)
nameBytes, err := v.Name.MarshalBinary()
if err != nil {
return nil, err
}
buffer.Write(nameBytes)
switch v.Type {
case VariableTypeInteger:
value := v.Value.(int32)
binary.Write(buffer, binary.LittleEndian, &value)
case VariableTypeOctetString:
octetString := &OctetString{Text: v.Value.(string)}
octetStringBytes, err := octetString.MarshalBinary()
if err != nil {
return nil, err
}
buffer.Write(octetStringBytes)
case VariableTypeNull, VariableTypeNoSuchObject, VariableTypeNoSuchInstance, VariableTypeEndOfMIBView:
break
case VariableTypeObjectIdentifier:
targetOID, err := value.ParseOID(v.Value.(string))
if err != nil {
return nil, err
}
oi := &ObjectIdentifier{}
oi.SetIdentifier(targetOID)
oiBytes, err := oi.MarshalBinary()
if err != nil {
return nil, err
}
buffer.Write(oiBytes)
case VariableTypeIPAddress:
ip := v.Value.(net.IP)
octetString := &OctetString{Text: string(ip)}
octetStringBytes, err := octetString.MarshalBinary()
if err != nil {
return nil, err
}
buffer.Write(octetStringBytes)
case VariableTypeCounter32, VariableTypeGauge32:
value := v.Value.(uint32)
binary.Write(buffer, binary.LittleEndian, &value)
case VariableTypeTimeTicks:
value := uint32(v.Value.(time.Duration).Seconds() * 100)
binary.Write(buffer, binary.LittleEndian, &value)
case VariableTypeOpaque:
octetString := &OctetString{Text: string(v.Value.([]byte))}
octetStringBytes, err := octetString.MarshalBinary()
if err != nil {
return nil, err
}
buffer.Write(octetStringBytes)
case VariableTypeCounter64:
value := v.Value.(uint64)
binary.Write(buffer, binary.LittleEndian, &value)
default:
return nil, fmt.Errorf("unhandled variable type %s", v.Type)
}
return buffer.Bytes(), nil
}
// UnmarshalBinary sets the packet structure from the provided slice of bytes.
func (v *Variable) UnmarshalBinary(data []byte) error {
buffer := bytes.NewBuffer(data)
if err := binary.Read(buffer, binary.LittleEndian, &v.Type); err != nil {
return err
}
offset := 4
if err := v.Name.UnmarshalBinary(data[offset:]); err != nil {
return err
}
offset += v.Name.ByteSize()
switch v.Type {
case VariableTypeInteger:
value := int32(0)
if err := binary.Read(buffer, binary.LittleEndian, &value); err != nil {
return err
}
v.Value = value
case VariableTypeOctetString:
octetString := &OctetString{}
if err := octetString.UnmarshalBinary(data[offset:]); err != nil {
return err
}
v.Value = octetString.Text
case VariableTypeNull, VariableTypeNoSuchObject, VariableTypeNoSuchInstance, VariableTypeEndOfMIBView:
v.Value = nil
case VariableTypeObjectIdentifier:
oid := &ObjectIdentifier{}
if err := oid.UnmarshalBinary(data[offset:]); err != nil {
return err
}
v.Value = oid.GetIdentifier()
case VariableTypeIPAddress:
octetString := &OctetString{}
if err := octetString.UnmarshalBinary(data[offset:]); err != nil {
return err
}
v.Value = net.IP(octetString.Text)
case VariableTypeCounter32, VariableTypeGauge32:
value := uint32(0)
if err := binary.Read(buffer, binary.LittleEndian, &value); err != nil {
return err
}
v.Value = value
case VariableTypeTimeTicks:
value := uint32(0)
if err := binary.Read(buffer, binary.LittleEndian, &value); err != nil {
return err
}
v.Value = time.Duration(value) * time.Second / 100
case VariableTypeOpaque:
octetString := &OctetString{}
if err := octetString.UnmarshalBinary(data[offset:]); err != nil {
return err
}
v.Value = []byte(octetString.Text)
case VariableTypeCounter64:
value := uint64(0)
if err := binary.Read(buffer, binary.LittleEndian, &value); err != nil {
return err
}
v.Value = value
default:
return fmt.Errorf("unhandled variable type %s", v.Type)
}
return nil
}
func (v *Variable) String() string {
return fmt.Sprintf("(variable %s = %v)", v.Type, v.Value)
}