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
|
'use strict';
const { Duplex } = require('stream');
/**
* Emits the `'close'` event on a stream.
*
* @param {Duplex} stream The stream.
* @private
*/
function emitClose(stream) {
stream.emit('close');
}
/**
* The listener of the `'end'` event.
*
* @private
*/
function duplexOnEnd() {
if (!this.destroyed && this._writableState.finished) {
this.destroy();
}
}
/**
* The listener of the `'error'` event.
*
* @param {Error} err The error
* @private
*/
function duplexOnError(err) {
this.removeListener('error', duplexOnError);
this.destroy();
if (this.listenerCount('error') === 0) {
// Do not suppress the throwing behavior.
this.emit('error', err);
}
}
/**
* Wraps a `WebSocket` in a duplex stream.
*
* @param {WebSocket} ws The `WebSocket` to wrap
* @param {Object} [options] The options for the `Duplex` constructor
* @return {Duplex} The duplex stream
* @public
*/
function createWebSocketStream(ws, options) {
let resumeOnReceiverDrain = true;
let terminateOnDestroy = true;
function receiverOnDrain() {
if (resumeOnReceiverDrain) ws._socket.resume();
}
if (ws.readyState === ws.CONNECTING) {
ws.once('open', function open() {
ws._receiver.removeAllListeners('drain');
ws._receiver.on('drain', receiverOnDrain);
});
} else {
ws._receiver.removeAllListeners('drain');
ws._receiver.on('drain', receiverOnDrain);
}
const duplex = new Duplex({
...options,
autoDestroy: false,
emitClose: false,
objectMode: false,
writableObjectMode: false
});
ws.on('message', function message(msg) {
if (!duplex.push(msg)) {
resumeOnReceiverDrain = false;
ws._socket.pause();
}
});
ws.once('error', function error(err) {
if (duplex.destroyed) return;
// Prevent `ws.terminate()` from being called by `duplex._destroy()`.
//
// - If the `'error'` event is emitted before the `'open'` event, then
// `ws.terminate()` is a noop as no socket is assigned.
// - Otherwise, the error is re-emitted by the listener of the `'error'`
// event of the `Receiver` object. The listener already closes the
// connection by calling `ws.close()`. This allows a close frame to be
// sent to the other peer. If `ws.terminate()` is called right after this,
// then the close frame might not be sent.
terminateOnDestroy = false;
duplex.destroy(err);
});
ws.once('close', function close() {
if (duplex.destroyed) return;
duplex.push(null);
});
duplex._destroy = function (err, callback) {
if (ws.readyState === ws.CLOSED) {
callback(err);
process.nextTick(emitClose, duplex);
return;
}
let called = false;
ws.once('error', function error(err) {
called = true;
callback(err);
});
ws.once('close', function close() {
if (!called) callback(err);
process.nextTick(emitClose, duplex);
});
if (terminateOnDestroy) ws.terminate();
};
duplex._final = function (callback) {
if (ws.readyState === ws.CONNECTING) {
ws.once('open', function open() {
duplex._final(callback);
});
return;
}
// If the value of the `_socket` property is `null` it means that `ws` is a
// client websocket and the handshake failed. In fact, when this happens, a
// socket is never assigned to the websocket. Wait for the `'error'` event
// that will be emitted by the websocket.
if (ws._socket === null) return;
if (ws._socket._writableState.finished) {
callback();
if (duplex._readableState.endEmitted) duplex.destroy();
} else {
ws._socket.once('finish', function finish() {
// `duplex` is not destroyed here because the `'end'` event will be
// emitted on `duplex` after this `'finish'` event. The EOF signaling
// `null` chunk is, in fact, pushed when the websocket emits `'close'`.
callback();
});
ws.close();
}
};
duplex._read = function () {
if (
(ws.readyState === ws.OPEN || ws.readyState === ws.CLOSING) &&
!resumeOnReceiverDrain
) {
resumeOnReceiverDrain = true;
if (!ws._receiver._writableState.needDrain) ws._socket.resume();
}
};
duplex._write = function (chunk, encoding, callback) {
if (ws.readyState === ws.CONNECTING) {
ws.once('open', function open() {
duplex._write(chunk, encoding, callback);
});
return;
}
ws.send(chunk, callback);
};
duplex.on('end', duplexOnEnd);
duplex.on('error', duplexOnError);
return duplex;
}
module.exports = createWebSocketStream;
|
