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
186
187
188
189
190
191
192
193
194
195
196
197
|
package gomemcached
import (
"encoding/binary"
"fmt"
"io"
)
// The maximum reasonable body length to expect.
// Anything larger than this will result in an error.
// The current limit, 20MB, is the size limit supported by ep-engine.
var MaxBodyLen = int(20 * 1024 * 1024)
// MCRequest is memcached Request
type MCRequest struct {
// The command being issued
Opcode CommandCode
// The CAS (if applicable, or 0)
Cas uint64
// An opaque value to be returned with this request
Opaque uint32
// The vbucket to which this command belongs
VBucket uint16
// Command extras, key, and body
Extras, Key, Body, ExtMeta []byte
// Datatype identifier
DataType uint8
}
// Size gives the number of bytes this request requires.
func (req *MCRequest) Size() int {
return HDR_LEN + len(req.Extras) + len(req.Key) + len(req.Body) + len(req.ExtMeta)
}
// A debugging string representation of this request
func (req MCRequest) String() string {
return fmt.Sprintf("{MCRequest opcode=%s, bodylen=%d, key='%s'}",
req.Opcode, len(req.Body), req.Key)
}
func (req *MCRequest) fillHeaderBytes(data []byte) int {
pos := 0
data[pos] = REQ_MAGIC
pos++
data[pos] = byte(req.Opcode)
pos++
binary.BigEndian.PutUint16(data[pos:pos+2],
uint16(len(req.Key)))
pos += 2
// 4
data[pos] = byte(len(req.Extras))
pos++
// Data type
if req.DataType != 0 {
data[pos] = byte(req.DataType)
}
pos++
binary.BigEndian.PutUint16(data[pos:pos+2], req.VBucket)
pos += 2
// 8
binary.BigEndian.PutUint32(data[pos:pos+4],
uint32(len(req.Body)+len(req.Key)+len(req.Extras)+len(req.ExtMeta)))
pos += 4
// 12
binary.BigEndian.PutUint32(data[pos:pos+4], req.Opaque)
pos += 4
// 16
if req.Cas != 0 {
binary.BigEndian.PutUint64(data[pos:pos+8], req.Cas)
}
pos += 8
if len(req.Extras) > 0 {
copy(data[pos:pos+len(req.Extras)], req.Extras)
pos += len(req.Extras)
}
if len(req.Key) > 0 {
copy(data[pos:pos+len(req.Key)], req.Key)
pos += len(req.Key)
}
return pos
}
// HeaderBytes will return the wire representation of the request header
// (with the extras and key).
func (req *MCRequest) HeaderBytes() []byte {
data := make([]byte, HDR_LEN+len(req.Extras)+len(req.Key))
req.fillHeaderBytes(data)
return data
}
// Bytes will return the wire representation of this request.
func (req *MCRequest) Bytes() []byte {
data := make([]byte, req.Size())
pos := req.fillHeaderBytes(data)
if len(req.Body) > 0 {
copy(data[pos:pos+len(req.Body)], req.Body)
}
if len(req.ExtMeta) > 0 {
copy(data[pos+len(req.Body):pos+len(req.Body)+len(req.ExtMeta)], req.ExtMeta)
}
return data
}
// Transmit will send this request message across a writer.
func (req *MCRequest) Transmit(w io.Writer) (n int, err error) {
if len(req.Body) < 128 {
n, err = w.Write(req.Bytes())
} else {
n, err = w.Write(req.HeaderBytes())
if err == nil {
m := 0
m, err = w.Write(req.Body)
n += m
}
}
return
}
// Receive will fill this MCRequest with the data from a reader.
func (req *MCRequest) Receive(r io.Reader, hdrBytes []byte) (int, error) {
if len(hdrBytes) < HDR_LEN {
hdrBytes = []byte{
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0}
}
n, err := io.ReadFull(r, hdrBytes)
if err != nil {
return n, err
}
if hdrBytes[0] != RES_MAGIC && hdrBytes[0] != REQ_MAGIC {
return n, fmt.Errorf("bad magic: 0x%02x", hdrBytes[0])
}
klen := int(binary.BigEndian.Uint16(hdrBytes[2:]))
elen := int(hdrBytes[4])
// Data type at 5
req.DataType = uint8(hdrBytes[5])
req.Opcode = CommandCode(hdrBytes[1])
// Vbucket at 6:7
req.VBucket = binary.BigEndian.Uint16(hdrBytes[6:])
totalBodyLen := int(binary.BigEndian.Uint32(hdrBytes[8:]))
req.Opaque = binary.BigEndian.Uint32(hdrBytes[12:])
req.Cas = binary.BigEndian.Uint64(hdrBytes[16:])
if totalBodyLen > 0 {
buf := make([]byte, totalBodyLen)
m, err := io.ReadFull(r, buf)
n += m
if err == nil {
if req.Opcode >= TAP_MUTATION &&
req.Opcode <= TAP_CHECKPOINT_END &&
len(buf) > 1 {
// In these commands there is "engine private"
// data at the end of the extras. The first 2
// bytes of extra data give its length.
elen += int(binary.BigEndian.Uint16(buf))
}
req.Extras = buf[0:elen]
req.Key = buf[elen : klen+elen]
// get the length of extended metadata
extMetaLen := 0
if elen > 29 {
extMetaLen = int(binary.BigEndian.Uint16(req.Extras[28:30]))
}
bodyLen := totalBodyLen - klen - elen - extMetaLen
if bodyLen > MaxBodyLen {
return n, fmt.Errorf("%d is too big (max %d)",
bodyLen, MaxBodyLen)
}
req.Body = buf[klen+elen : klen+elen+bodyLen]
req.ExtMeta = buf[klen+elen+bodyLen:]
}
}
return n, err
}
|
