Add session awareness to WebSocket node

This allows a websocket-in node to receive data, process it in a flow
and then send it back to the originating websocket client via a
websocket-out node.

nodes/core/io/22-websocket.js

@@ -43,6 +43,8 @@ function WebSocketListenerNode(n) {
         }
     }
 
+    node._clients = {};
+    
     RED.server.addListener('newListener',storeListener);
 
     // Create a WebSocket Server
@@ -53,8 +55,14 @@ function WebSocketListenerNode(n) {
     RED.server.removeListener('newListener',storeListener);
 
     node.server.on('connection', function(socket){
+        var id = (1+Math.random()*4294967295).toString(16);
+        node._clients[id] = socket;
+        
+        socket.on('close',function() {
+            delete node._clients[id];
+        });
         socket.on('message',function(data,flags){
-            node.handleEvent(socket,'message',data,flags);
+            node.handleEvent(id,socket,'message',data,flags);
         });
     });
 
@@ -80,9 +88,9 @@ WebSocketListenerNode.prototype.registerInputNode = function(/*Node*/handler){
     this._inputNodes.push(handler);
 }
 
-WebSocketListenerNode.prototype.handleEvent = function(/*socket*/socket,/*String*/event,/*Object*/data,/*Object*/flags){
+WebSocketListenerNode.prototype.handleEvent = function(id,/*socket*/socket,/*String*/event,/*Object*/data,/*Object*/flags){
     for (var i = 0; i < this._inputNodes.length; i++) {
-        this._inputNodes[i].send({payload:data});
+        this._inputNodes[i].send({session:{type:"websocket",id:id},payload:data});
     };
 }
 
@@ -92,6 +100,13 @@ WebSocketListenerNode.prototype.broadcast = function(data){
     };
 }
 
+WebSocketListenerNode.prototype.send = function(id,data){
+    var session = this._clients[id];
+    if (session) {
+        session.send(data);
+    }
+}
+
 function WebSocketInNode(n) {
     RED.nodes.createNode(this,n);
     this.server = n.server;
@@ -114,11 +129,23 @@ function WebSocketOutNode(n) {
         this.error("Missing server configuration");
     }
     this.on("input", function(msg) {
-        node.serverConfig.broadcast(msg.payload,function(error){
-            if(!!error){
-                node.warn("An error occurred while sending:" + inspect(error));
-            }
-        });
+        var payload = msg.payload;
+        if (Buffer.isBuffer(payload)) {
+            payload = payload.toString();
+        } else if (typeof payload === "object") {
+            payload = JSON.stringify(payload);
+        } else if (typeof payload !== "string") {
+            payload = ""+payload;
+        }
+        if (msg.session && msg.session.type == "websocket") {
+            node.serverConfig.send(msg.session.id,payload);
+        } else {
+            node.serverConfig.broadcast(payload,function(error){
+                if(!!error){
+                    node.warn("An error occurred while sending:" + inspect(error));
+                }
+            });
+        }
     });
 }
 RED.nodes.registerType("websocket out",WebSocketOutNode);