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
|
//go:build !js
package websocket
import (
"bufio"
"encoding/binary"
"fmt"
"io"
"math"
"github.com/coder/websocket/internal/errd"
)
// opcode represents a WebSocket opcode.
type opcode int
// https://tools.ietf.org/html/rfc6455#section-11.8.
const (
opContinuation opcode = iota
opText
opBinary
// 3 - 7 are reserved for further non-control frames.
_
_
_
_
_
opClose
opPing
opPong
// 11-16 are reserved for further control frames.
)
// header represents a WebSocket frame header.
// See https://tools.ietf.org/html/rfc6455#section-5.2.
type header struct {
fin bool
rsv1 bool
rsv2 bool
rsv3 bool
opcode opcode
payloadLength int64
masked bool
maskKey uint32
}
// readFrameHeader reads a header from the reader.
// See https://tools.ietf.org/html/rfc6455#section-5.2.
func readFrameHeader(r *bufio.Reader, readBuf []byte) (h header, err error) {
defer errd.Wrap(&err, "failed to read frame header")
b, err := r.ReadByte()
if err != nil {
return header{}, err
}
h.fin = b&(1<<7) != 0
h.rsv1 = b&(1<<6) != 0
h.rsv2 = b&(1<<5) != 0
h.rsv3 = b&(1<<4) != 0
h.opcode = opcode(b & 0xf)
b, err = r.ReadByte()
if err != nil {
return header{}, err
}
h.masked = b&(1<<7) != 0
payloadLength := b &^ (1 << 7)
switch {
case payloadLength < 126:
h.payloadLength = int64(payloadLength)
case payloadLength == 126:
_, err = io.ReadFull(r, readBuf[:2])
h.payloadLength = int64(binary.BigEndian.Uint16(readBuf))
case payloadLength == 127:
_, err = io.ReadFull(r, readBuf)
h.payloadLength = int64(binary.BigEndian.Uint64(readBuf))
}
if err != nil {
return header{}, err
}
if h.payloadLength < 0 {
return header{}, fmt.Errorf("received negative payload length: %v", h.payloadLength)
}
if h.masked {
_, err = io.ReadFull(r, readBuf[:4])
if err != nil {
return header{}, err
}
h.maskKey = binary.LittleEndian.Uint32(readBuf)
}
return h, nil
}
// maxControlPayload is the maximum length of a control frame payload.
// See https://tools.ietf.org/html/rfc6455#section-5.5.
const maxControlPayload = 125
// writeFrameHeader writes the bytes of the header to w.
// See https://tools.ietf.org/html/rfc6455#section-5.2
func writeFrameHeader(h header, w *bufio.Writer, buf []byte) (err error) {
defer errd.Wrap(&err, "failed to write frame header")
var b byte
if h.fin {
b |= 1 << 7
}
if h.rsv1 {
b |= 1 << 6
}
if h.rsv2 {
b |= 1 << 5
}
if h.rsv3 {
b |= 1 << 4
}
b |= byte(h.opcode)
err = w.WriteByte(b)
if err != nil {
return err
}
lengthByte := byte(0)
if h.masked {
lengthByte |= 1 << 7
}
switch {
case h.payloadLength > math.MaxUint16:
lengthByte |= 127
case h.payloadLength > 125:
lengthByte |= 126
case h.payloadLength >= 0:
lengthByte |= byte(h.payloadLength)
}
err = w.WriteByte(lengthByte)
if err != nil {
return err
}
switch {
case h.payloadLength > math.MaxUint16:
binary.BigEndian.PutUint64(buf, uint64(h.payloadLength))
_, err = w.Write(buf)
case h.payloadLength > 125:
binary.BigEndian.PutUint16(buf, uint16(h.payloadLength))
_, err = w.Write(buf[:2])
}
if err != nil {
return err
}
if h.masked {
binary.LittleEndian.PutUint32(buf, h.maskKey)
_, err = w.Write(buf[:4])
if err != nil {
return err
}
}
return nil
}
|
