nodejs之websocket

Posted 2020-10-03 依然是等待

  1 var events = require("events");
  2 var http = require("http");
  3 var crypto = require("crypto");
  4 var util = require("util");
  5 //opcodes for WebSocket frames
  6 //http://tools.ietf.org/html/rfc6455#section-5.2
  7 var opcodes = 
  8 {
  9     TEXT:1,
 10     BINARY:2,
 11     CLOSE:8,
 12     PING:9,
 13     PONG:10
 14 };
 15 var WebSocketConnection = function(req,socket,upgradeHead)
 16 {
 17     var self = this;
 18     var key = hashWebSocketKey(req.headers["sec-websocket-key"]);
 19     //handshake response
 20     //http://tools.ietf.org/html/rfc6455#section-4.2.2
 21     socket.write(‘HTTP/1.1 101 Web Socket Protocol Handshake\r\n‘+
 22     ‘Upgrade:WebSocket\r\n‘+
 23     ‘Connection:Upgrade\r\n‘+
 24     ‘sec-websocket-accept: ‘+key+‘\r\n\r\n‘);
 25     
 26     socket.on("data",function(buf)
 27     {
 28         self.buffer = Buffer.concat([self.buffer,buff]);
 29         while(self._processBuffer())
 30         {
 31             //process buffer while it contains complete frames
 32         }
 33     });    
 34     
 35     socket.on("close",function(hac_error)
 36     {
 37         if(!self.closed)
 38         {
 39             self.emit("close",1006);
 40             self.closed = true;
 41         }
 42     });
 43     // initialize connection state
 44     this.socket = socket;
 45     this.buffer = new Buffer(0);
 46     this.colsed = false;
 47     
 48 }
 49 
 50 util.inherits(WebSocketConnection,events.EventEmitter);
 51 // Send a text or binary message on the WebSocket connection
 52 
 53 WebSocketConnection.prototype.send = function(obj)
 54 {
 55     var opcode;
 56     var payload;
 57     if(Buffer.isBuffer(obj))
 58     {
 59         opcode = opcodes.BINARY;
 60         payload = obj;
 61     }
 62     else
 63     {
 64         throw new Error("Cannot send object. Must be string or Buffer");
 65     }
 66     this._doSend(opcode,payload);
 67 }
 68 //Close the WebSocket connection
 69 WebSocketConnection.prototype.close = function(code,reason)
 70 {
 71     var opcode = opcodes.CLOSE;
 72     var buffer;
 73     //Encode close and reason
 74     if(code)
 75     {
 76         buffer = new Buffer(Buffer.byteLength(reason)+2);
 77         buffer.writeUInt16BE(code,0);
 78         buffer.write(reason,2);
 79     }
 80     else
 81     {
 82         buffer = new Buffer(0);
 83     }
 84     this._doSend(opcode,buffer);
 85     this.close = true;
 86     
 87 }
 88 //process incoming bytes
 89 WebSocketConnection.prototype._processBuffer = function()
 90 {
 91     var buf = this.buffer;
 92     if(buf.length < 2)
 93     {
 94         //insufficient data read
 95         return;
 96     }
 97     
 98     var idx = 2;
 99     var b1 = buf.readUInt8(0);
100     var fin = b1 & 0x80;
101     var opcode = b1 & 0x0f;
102     var b2 = buf.readUInt8(1);
103     var mask = b2 & 0x80;
104     var length = b2 & 0x7f;
105     
106     if(length > 125)
107     {
108         if(buf.length < 8)
109         {
110             //insufficient data read
111             return;
112         }
113         
114         if(length == 126)
115         {
116             length = buf.readUInt16BE(2);
117             idx += 2;
118         }
119         else if(length == 127)
120         {
121             //discard high 4 bits because this server cannot handle huge lengths
122             var highBits = buf.readUInt32BE(2);
123             if(highBits != 0)
124             {
125                 this.close(1009,"");
126             }
127             length = buf.readUInt32BE(6);
128             idx += 8;
129         }
130     }
131     
132     if(buf.length < idx + 4 + length)
133     {
134         //insufficient data read
135         return;
136     }
137     
138     maskBytes = buf.slice(idx,idx+4);
139     idx += 4;
140     var payload = buf.slice(idx,idx+length);
141     payload = unmask(maskBytes,payload);
142     this._handleFreme(opcode,payload);
143     
144     this.buffer = buf.slice(idx+length);
145     return true;
146 }
147 
148 WebSocketConnection.prototype._handleFrame = function(opcode,buffer)
149 {
150     var payload;
151     switch(opcode)
152     {
153         case opcodes.TEXT:
154             payload = buffer.toString("utf8");
155             this.emit("data",opcode,payload);
156             break;
157         case opcode.BINARY:
158             payload = buffer;
159             this.emit("data",opcode,payload);
160             break;
161         case opcode.PING:
162             //Respond to pings with pongs
163             this._doSend(opcode.PONG,buffer);
164             break;
165         case opcode.PONG:
166         //Ignore pongs;
167             break;
168         case opcode.CLOSE:
169             //Parse close and reason
170             var code,reason;
171             if(buffer.length >= 2)
172             {
173                 code = buffer.readUInt16BE(0);
174                 reason = buffer.toString("utf8",2);
175             }
176             this.close(code,reason);
177             this.emit("close",code,reason);
178             break;
179         default:
180             this.close(1002,"unknown opcode");
181         
182     }
183 }
184 //Format and send a WebSocket message
185 WebSocketConnection.prototype._doSend = function(opcode,payload)
186 {
187     this.socket.write(encodeMessage(opcode,payload));
188 }
189 
190 var KEY_SUFFIX = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
191 var hashWebSocketKey = function(key)
192 {
193     var sha1 = crypto.createHash("sha1");
194     sha1.update(key+KEY_SUFFIX,"ascii");
195     return sha1.digest("base64");
196 }
197 
198 var unmask = function(maskBytes,data)
199 {
200     var payload = new Buffer(data.length);
201     for(var i=0;i<data.length;i++)
202     {
203         payload[] = maskBytes[i%4] ^ data[i];
204     }
205     
206     return payload;
207     
208 }
209 
210 var encodeMessage = function(opcode,payload)
211 {
212     var buf;
213     //first byte:fin and opcode
214     var b1 = 0x80 | opcode;
215     //always send message as one frame(fin)
216     //Second byte:mask and length part 1
217     //Followed by 0,2, or 8 additional bytes of continued length
218     var b2 = 0;//server does not mask frames
219     var length = payload.length;
220     if(length < 126)
221     {
222         buf = new Buffer(payload.length + 2 + 0);
223         //zero extra bytes
224         b2 |= length;
225         buf.writeUInt8BE(b1,0);
226         buf.writeUInt8BE(b1,1);
227         payload.copy(buf.2);
228     }
229     else if(length<(1<<16))
230     {
231         buf = new Buffer(payload.length + 2 + 2);
232         //two bytes extra
233         b2 |= 126;
234         buf.writeUInt8BE(b1,0);
235         buf.writeUInt8BE(b1,1);
236         //add two tyte length
237         buf.writeUInt16BE(length,2);
238         payload.copy(buf,4);
239     }
240     else
241     {
242         buf = new Buffer(payload.length + 2 + 8);
243         //eight bytes extra
244         b2 |= 127;
245         buf.writeUInt8(b1,0);
246         buf.writeUInt8(b1,1);
247         //add eigth byte length
248         //note:this implementation cannt handle lengths greater than 2^32
249         //the 32 bit length is prefixed with 0X0000
250         buf.writeUInt32BE(0,2);
251         buf.writeUInt32BE(length,6);
252         payload.copy(buf,10);
253     }
254     
255     return;
256 }
257 
258 exports.listen = function(port,host,connectionHandler)
259 {
260     var srv = http.createServer(function(req,res){});
261 
262     srv.on(‘upgrade‘,function(req,socket,upgradeHead)
263     {
264         var ws = new WebSocketConnection(req,socket,upgradeHead);
265         connectionHandler(ws);
266     });
267     srv.listen(port,host);
268 };
269 
270 //echo.js
271 var websocket = require("./websocket-example");
272 websocket.listen(9999,"localhost",function(conn)
273 {
274     console.log("connection opened");
275     conn.on("data",function(opcode,data)
276     {
277         console.log("message: ",data);
278         conn.send(data);
279     });
280     
281     conn.on("close",function(code,reason)
282     {
283         console.log("connection closed: ",code,reason);
284         
285     });
286     
287 });