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/** |
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* Web Sockets server. |
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* |
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* @module src/ws-server |
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*/ |
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"use strict"; |
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const WebSocket = require("ws"); |
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/** |
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* Server object prototype. |
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*/ |
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const wsServerProto = { |
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/** |
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* Underlying Web Sockets server instance. |
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* |
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* @type {WebSocket.Server} |
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*/ |
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server: null, |
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/** |
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* Broadcasts a message to all connected clients. |
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* |
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* @param {any} data Message to send. |
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* @param {WebSocket} [exclude] WebSocket instance to exclude from broadcast (if any). |
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*/ |
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broadcast: function broadcast(data, exclude) { |
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this.server.clients.forEach(function(client) { |
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if (exclude === client || client.readyState !== WebSocket.OPEN) { |
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return; |
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} |
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client.send(data); |
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}); |
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}, |
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/** |
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* Broadcasts an object as a JSON string to all connected clients. |
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* |
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* @param {object} data Object to send. |
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* @param {WebSocket} [exclude] WebSocket instance to exclude from broadcast (if any). |
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*/ |
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broadcastJSON: function broadcastJSON(data, exclude) { |
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this.broadcast(JSON.stringify(data), exclude); |
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}, |
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/** |
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* Sends an object as a JSON string to a specific client. |
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* |
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* @param {WebSocket} socket WebSocket instance to send to. |
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* @param {object} data Object to send. |
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*/ |
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sendJSON: function sendJSON(socket, data) { |
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socket.send(JSON.stringify(data)); |
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} |
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}; |
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/** |
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* Handles an incoming connection. |
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* |
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* @param {WebSocket} socket WebSocket instance. |
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* @param {http.IncomingMessage} req Request object. |
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* @param {object} config Server instance configuration object. |
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*/ |
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function handleConnection(socket, req, config) { |
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// set up client object |
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let client = { |
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socket: socket, |
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request: req |
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}; |
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// set up message handler, if any |
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if (typeof config.messageHandler == "function") { |
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socket.on("message", function(data) { |
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config.messageHandler(data, client); |
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}); |
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} |
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// set up error handler, if any |
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if (typeof config.errorHandler == "function") { |
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socket.on("error", function(err) { |
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config.errorHandler(err, client); |
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}); |
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} |
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// set up disconnection handler, if any |
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if (typeof config.closeHandler == "function") { |
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socket.on("close", function(code, reason) { |
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config.closeHandler(code, reason, client); |
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}); |
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} |
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// set up ping cycle, if requested |
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if (config.timeout) { |
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socket.pingPending = false; |
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socket.on("pong", function() { |
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socket.pingPending = false; |
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}); |
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} |
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// call connection handler, if any |
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if (typeof config.connectionHandler == "function") { |
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config.connectionHandler(client); |
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} |
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} |
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/** |
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* Pings a connected client, disconnecting it in case of no response from last ping. |
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* |
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* @param {WebSocket} socket WebSocket instance. |
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*/ |
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function ping(socket) { |
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// forcibly close connection if no reply since last ping |
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if (socket.pingPending) { |
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socket.terminate(); |
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return; |
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} |
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// send next ping |
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socket.pingPending = true; |
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socket.ping("", false, true); |
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} |
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/** |
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* Creates a new server instance. |
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* |
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* @param {object} serverOptions Construction options for the underlying Web |
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* Sockets server. Note that the clientTracking |
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* and handleProtocols properties are overwritten. |
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* @param {object} [config] Configuration object: |
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* @param {number} [config.timeout] Ping timeout in milliseconds. |
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* @param {function} [config.protocolHandler] Protocol selection handler. |
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* @param {function} [config.connectionHandler] Connection handler. |
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* @param {function} [config.messageHandler] Message reception handler. |
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* @param {function} [config.errorHandler] Error handler. |
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* @param {function} [config.closeHandler] Disconnection handler. |
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*/ |
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function createServer(serverOptions, config) { |
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config = config || {}; |
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// set up protocol handler, if any |
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if (typeof config.protocolHandler == "function") { |
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serverOptions.handleProtocols = config.protocolHandler; |
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} |
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// set up Web Sockets server |
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serverOptions.clientTracking = true; |
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let server = new WebSocket.Server(serverOptions); |
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server.on("connection", function(socket, req) { |
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handleConnection(socket, req, config); |
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}); |
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// start ping cycle, if requested |
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if (config.timeout) { |
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setInterval(function() { |
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server.clients.forEach(ping); |
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}, config.timeout); |
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} |
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// create and return server instance |
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let wsServer = Object.create(wsServerProto); |
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wsServer.server = server; |
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return wsServer; |
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} |
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module.exports = createServer; |
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