summaryrefslogtreecommitdiff
path: root/libgo/go/websocket/client.go
blob: 09134594405b7572597174e0b2a9a6b5a9bdf643 (plain)
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
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
// 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 (
	"bufio"
	"bytes"
	"container/vector"
	"crypto/tls"
	"fmt"
	"http"
	"io"
	"net"
	"os"
	"rand"
	"strings"
)

type ProtocolError struct {
	os.ErrorString
}

var (
	ErrBadScheme            = os.ErrorString("bad scheme")
	ErrBadStatus            = &ProtocolError{"bad status"}
	ErrBadUpgrade           = &ProtocolError{"missing or bad upgrade"}
	ErrBadWebSocketOrigin   = &ProtocolError{"missing or bad WebSocket-Origin"}
	ErrBadWebSocketLocation = &ProtocolError{"missing or bad WebSocket-Location"}
	ErrBadWebSocketProtocol = &ProtocolError{"missing or bad WebSocket-Protocol"}
	ErrChallengeResponse    = &ProtocolError{"mismatch challange/response"}
	secKeyRandomChars       [0x30 - 0x21 + 0x7F - 0x3A]byte
)

type DialError struct {
	URL      string
	Protocol string
	Origin   string
	Error    os.Error
}

func (e *DialError) String() string {
	return "websocket.Dial " + e.URL + ": " + e.Error.String()
}

func init() {
	i := 0
	for ch := byte(0x21); ch < 0x30; ch++ {
		secKeyRandomChars[i] = ch
		i++
	}
	for ch := byte(0x3a); ch < 0x7F; ch++ {
		secKeyRandomChars[i] = ch
		i++
	}
}

type handshaker func(resourceName, host, origin, location, protocol string, br *bufio.Reader, bw *bufio.Writer) os.Error

// newClient creates a new Web Socket client connection.
func newClient(resourceName, host, origin, location, protocol string, rwc io.ReadWriteCloser, handshake handshaker) (ws *Conn, err os.Error) {
	br := bufio.NewReader(rwc)
	bw := bufio.NewWriter(rwc)
	err = handshake(resourceName, host, origin, location, protocol, br, bw)
	if err != nil {
		return
	}
	buf := bufio.NewReadWriter(br, bw)
	ws = newConn(origin, location, protocol, buf, rwc)
	return
}

/*
Dial opens a new client connection to a Web Socket.

A trivial example client:

	package main

	import (
		"websocket"
		"strings"
	)

	func main() {
	 	ws, err := websocket.Dial("ws://localhost/ws", "", "http://localhost/");
	 	if err != nil {
			panic("Dial: " + err.String())
		}
		if _, err := ws.Write([]byte("hello, world!\n")); err != nil {
			panic("Write: " + err.String())
		}
		var msg = make([]byte, 512);
		if n, err := ws.Read(msg); err != nil {
			panic("Read: " + err.String())
		}
		// use msg[0:n]
	}
*/
func Dial(url, protocol, origin string) (ws *Conn, err os.Error) {
	var client net.Conn

	parsedUrl, err := http.ParseURL(url)
	if err != nil {
		goto Error
	}

	switch parsedUrl.Scheme {
	case "ws":
		client, err = net.Dial("tcp", "", parsedUrl.Host)

	case "wss":
		client, err = tls.Dial("tcp", "", parsedUrl.Host, nil)

	default:
		err = ErrBadScheme
	}
	if err != nil {
		goto Error
	}

	ws, err = newClient(parsedUrl.RawPath, parsedUrl.Host, origin, url, protocol, client, handshake)
	if err != nil {
		goto Error
	}
	return

Error:
	return nil, &DialError{url, protocol, origin, err}
}

/*
Generates handshake key as described in 4.1 Opening handshake step 16 to 22.
cf. http://www.whatwg.org/specs/web-socket-protocol/
*/
func generateKeyNumber() (key string, number uint32) {
	// 16.  Let /spaces_n/ be a random integer from 1 to 12 inclusive.
	spaces := rand.Intn(12) + 1

	// 17. Let /max_n/ be the largest integer not greater than
	//     4,294,967,295 divided by /spaces_n/
	max := int(4294967295 / uint32(spaces))

	// 18. Let /number_n/ be a random integer from 0 to /max_n/ inclusive.
	number = uint32(rand.Intn(max + 1))

	// 19. Let /product_n/ be the result of multiplying /number_n/ and
	//     /spaces_n/ together.
	product := number * uint32(spaces)

	// 20. Let /key_n/ be a string consisting of /product_n/, expressed
	// in base ten using the numerals in the range U+0030 DIGIT ZERO (0)
	// to U+0039 DIGIT NINE (9).
	key = fmt.Sprintf("%d", product)

	// 21. Insert between one and twelve random characters from the ranges
	//     U+0021 to U+002F and U+003A to U+007E into /key_n/ at random
	//     positions.
	n := rand.Intn(12) + 1
	for i := 0; i < n; i++ {
		pos := rand.Intn(len(key)) + 1
		ch := secKeyRandomChars[rand.Intn(len(secKeyRandomChars))]
		key = key[0:pos] + string(ch) + key[pos:]
	}

	// 22. Insert /spaces_n/ U+0020 SPACE characters into /key_n/ at random
	//     positions other than the start or end of the string.
	for i := 0; i < spaces; i++ {
		pos := rand.Intn(len(key)-1) + 1
		key = key[0:pos] + " " + key[pos:]
	}

	return
}

/*
Generates handshake key_3 as described in 4.1 Opening handshake step 26.
cf. http://www.whatwg.org/specs/web-socket-protocol/
*/
func generateKey3() (key []byte) {
	// 26. Let /key3/ be a string consisting of eight random bytes (or
	//  equivalently, a random 64 bit integer encoded in big-endian order).
	key = make([]byte, 8)
	for i := 0; i < 8; i++ {
		key[i] = byte(rand.Intn(256))
	}
	return
}

/*
Web Socket protocol handshake based on
http://www.whatwg.org/specs/web-socket-protocol/
(draft of http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol)
*/
func handshake(resourceName, host, origin, location, protocol string, br *bufio.Reader, bw *bufio.Writer) (err os.Error) {
	// 4.1. Opening handshake.
	// Step 5.  send a request line.
	bw.WriteString("GET " + resourceName + " HTTP/1.1\r\n")

	// Step 6-14. push request headers in fields.
	var fields vector.StringVector
	fields.Push("Upgrade: WebSocket\r\n")
	fields.Push("Connection: Upgrade\r\n")
	fields.Push("Host: " + host + "\r\n")
	fields.Push("Origin: " + origin + "\r\n")
	if protocol != "" {
		fields.Push("Sec-WebSocket-Protocol: " + protocol + "\r\n")
	}
	// TODO(ukai): Step 15. send cookie if any.

	// Step 16-23. generate keys and push Sec-WebSocket-Key<n> in fields.
	key1, number1 := generateKeyNumber()
	key2, number2 := generateKeyNumber()
	fields.Push("Sec-WebSocket-Key1: " + key1 + "\r\n")
	fields.Push("Sec-WebSocket-Key2: " + key2 + "\r\n")

	// Step 24. shuffle fields and send them out.
	for i := 1; i < len(fields); i++ {
		j := rand.Intn(i)
		fields[i], fields[j] = fields[j], fields[i]
	}
	for i := 0; i < len(fields); i++ {
		bw.WriteString(fields[i])
	}
	// Step 25. send CRLF.
	bw.WriteString("\r\n")

	// Step 26. genearte 8 bytes random key.
	key3 := generateKey3()
	// Step 27. send it out.
	bw.Write(key3)
	if err = bw.Flush(); err != nil {
		return
	}

	// Step 28-29, 32-40. read response from server.
	resp, err := http.ReadResponse(br, "GET")
	if err != nil {
		return err
	}
	// Step 30. check response code is 101.
	if resp.StatusCode != 101 {
		return ErrBadStatus
	}

	// Step 41. check websocket headers.
	if resp.Header["Upgrade"] != "WebSocket" ||
		strings.ToLower(resp.Header["Connection"]) != "upgrade" {
		return ErrBadUpgrade
	}

	if resp.Header["Sec-Websocket-Origin"] != origin {
		return ErrBadWebSocketOrigin
	}

	if resp.Header["Sec-Websocket-Location"] != location {
		return ErrBadWebSocketLocation
	}

	if protocol != "" && resp.Header["Sec-Websocket-Protocol"] != protocol {
		return ErrBadWebSocketProtocol
	}

	// Step 42-43. get expected data from challange data.
	expected, err := getChallengeResponse(number1, number2, key3)
	if err != nil {
		return err
	}

	// Step 44. read 16 bytes from server.
	reply := make([]byte, 16)
	if _, err = io.ReadFull(br, reply); err != nil {
		return err
	}

	// Step 45. check the reply equals to expected data.
	if !bytes.Equal(expected, reply) {
		return ErrChallengeResponse
	}
	// WebSocket connection is established.
	return
}

/*
Handhake described in (soon obsolete)
draft-hixie-thewebsocket-protocol-75.
*/
func draft75handshake(resourceName, host, origin, location, protocol string, br *bufio.Reader, bw *bufio.Writer) (err os.Error) {
	bw.WriteString("GET " + resourceName + " HTTP/1.1\r\n")
	bw.WriteString("Upgrade: WebSocket\r\n")
	bw.WriteString("Connection: Upgrade\r\n")
	bw.WriteString("Host: " + host + "\r\n")
	bw.WriteString("Origin: " + origin + "\r\n")
	if protocol != "" {
		bw.WriteString("WebSocket-Protocol: " + protocol + "\r\n")
	}
	bw.WriteString("\r\n")
	bw.Flush()
	resp, err := http.ReadResponse(br, "GET")
	if err != nil {
		return
	}
	if resp.Status != "101 Web Socket Protocol Handshake" {
		return ErrBadStatus
	}
	if resp.Header["Upgrade"] != "WebSocket" ||
		resp.Header["Connection"] != "Upgrade" {
		return ErrBadUpgrade
	}
	if resp.Header["Websocket-Origin"] != origin {
		return ErrBadWebSocketOrigin
	}
	if resp.Header["Websocket-Location"] != location {
		return ErrBadWebSocketLocation
	}
	if protocol != "" && resp.Header["Websocket-Protocol"] != protocol {
		return ErrBadWebSocketProtocol
	}
	return
}