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
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package websocket
import (
"http"
"io"
"strings"
)
/*
Handler is an interface to a WebSocket.
A trivial example server:
package main
import (
"http"
"io"
"websocket"
)
// Echo the data received on the Web Socket.
func EchoServer(ws *websocket.Conn) {
io.Copy(ws, ws);
}
func main() {
http.Handle("/echo", websocket.Handler(EchoServer));
err := http.ListenAndServe(":12345", nil);
if err != nil {
panic("ListenAndServe: " + err.String())
}
}
*/
type Handler func(*Conn)
/*
Gets key number from Sec-WebSocket-Key<n>: field as described
in 5.2 Sending the server's opening handshake, 4.
*/
func getKeyNumber(s string) (r uint32) {
// 4. Let /key-number_n/ be the digits (characters in the range
// U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9)) in /key_1/,
// interpreted as a base ten integer, ignoring all other characters
// in /key_n/.
r = 0
for i := 0; i < len(s); i++ {
if s[i] >= '0' && s[i] <= '9' {
r = r*10 + uint32(s[i]) - '0'
}
}
return
}
// ServeHTTP implements the http.Handler interface for a Web Socket
func (f Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
rwc, buf, err := w.Hijack()
if err != nil {
panic("Hijack failed: " + err.String())
return
}
// The server should abort the WebSocket connection if it finds
// the client did not send a handshake that matches with protocol
// specification.
defer rwc.Close()
if req.Method != "GET" {
return
}
// HTTP version can be safely ignored.
if strings.ToLower(req.Header.Get("Upgrade")) != "websocket" ||
strings.ToLower(req.Header.Get("Connection")) != "upgrade" {
return
}
// TODO(ukai): check Host
origin := req.Header.Get("Origin")
if origin == "" {
return
}
key1 := req.Header.Get("Sec-Websocket-Key1")
if key1 == "" {
return
}
key2 := req.Header.Get("Sec-Websocket-Key2")
if key2 == "" {
return
}
key3 := make([]byte, 8)
if _, err := io.ReadFull(buf, key3); err != nil {
return
}
var location string
if w.UsingTLS() {
location = "wss://" + req.Host + req.URL.RawPath
} else {
location = "ws://" + req.Host + req.URL.RawPath
}
// Step 4. get key number in Sec-WebSocket-Key<n> fields.
keyNumber1 := getKeyNumber(key1)
keyNumber2 := getKeyNumber(key2)
// Step 5. get number of spaces in Sec-WebSocket-Key<n> fields.
space1 := uint32(strings.Count(key1, " "))
space2 := uint32(strings.Count(key2, " "))
if space1 == 0 || space2 == 0 {
return
}
// Step 6. key number must be an integral multiple of spaces.
if keyNumber1%space1 != 0 || keyNumber2%space2 != 0 {
return
}
// Step 7. let part be key number divided by spaces.
part1 := keyNumber1 / space1
part2 := keyNumber2 / space2
// Step 8. let challenge to be concatination of part1, part2 and key3.
// Step 9. get MD5 fingerprint of challenge.
response, err := getChallengeResponse(part1, part2, key3)
if err != nil {
return
}
// Step 10. send response status line.
buf.WriteString("HTTP/1.1 101 WebSocket Protocol Handshake\r\n")
// Step 11. send response headers.
buf.WriteString("Upgrade: WebSocket\r\n")
buf.WriteString("Connection: Upgrade\r\n")
buf.WriteString("Sec-WebSocket-Location: " + location + "\r\n")
buf.WriteString("Sec-WebSocket-Origin: " + origin + "\r\n")
protocol := strings.TrimSpace(req.Header.Get("Sec-Websocket-Protocol"))
if protocol != "" {
buf.WriteString("Sec-WebSocket-Protocol: " + protocol + "\r\n")
}
// Step 12. send CRLF.
buf.WriteString("\r\n")
// Step 13. send response data.
buf.Write(response)
if err := buf.Flush(); err != nil {
return
}
ws := newConn(origin, location, protocol, buf, rwc)
f(ws)
}
/*
Draft75Handler is an interface to a WebSocket based on the
(soon obsolete) draft-hixie-thewebsocketprotocol-75.
*/
type Draft75Handler func(*Conn)
// ServeHTTP implements the http.Handler interface for a Web Socket.
func (f Draft75Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
if req.Method != "GET" || req.Proto != "HTTP/1.1" {
w.WriteHeader(http.StatusBadRequest)
io.WriteString(w, "Unexpected request")
return
}
if req.Header.Get("Upgrade") != "WebSocket" {
w.WriteHeader(http.StatusBadRequest)
io.WriteString(w, "missing Upgrade: WebSocket header")
return
}
if req.Header.Get("Connection") != "Upgrade" {
w.WriteHeader(http.StatusBadRequest)
io.WriteString(w, "missing Connection: Upgrade header")
return
}
origin := strings.TrimSpace(req.Header.Get("Origin"))
if origin == "" {
w.WriteHeader(http.StatusBadRequest)
io.WriteString(w, "missing Origin header")
return
}
rwc, buf, err := w.Hijack()
if err != nil {
panic("Hijack failed: " + err.String())
return
}
defer rwc.Close()
var location string
if w.UsingTLS() {
location = "wss://" + req.Host + req.URL.RawPath
} else {
location = "ws://" + req.Host + req.URL.RawPath
}
// TODO(ukai): verify origin,location,protocol.
buf.WriteString("HTTP/1.1 101 Web Socket Protocol Handshake\r\n")
buf.WriteString("Upgrade: WebSocket\r\n")
buf.WriteString("Connection: Upgrade\r\n")
buf.WriteString("WebSocket-Origin: " + origin + "\r\n")
buf.WriteString("WebSocket-Location: " + location + "\r\n")
protocol := strings.TrimSpace(req.Header.Get("Websocket-Protocol"))
// canonical header key of WebSocket-Protocol.
if protocol != "" {
buf.WriteString("WebSocket-Protocol: " + protocol + "\r\n")
}
buf.WriteString("\r\n")
if err := buf.Flush(); err != nil {
return
}
ws := newConn(origin, location, protocol, buf, rwc)
f(ws)
}
|
