[minor] Add shouldHandle() method to WebSocketServer

Moved the check to see if a `WebSocketServer` instance should handle a
given request into a public method. This will allow people to override
this logic with a patch if they desire.

lib/WebSocketServer.js

@@ -156,21 +156,35 @@ WebSocketServer.prototype.close = function (callback) {
 };
 
 /**
- * Handle a HTTP Upgrade request.
+ * See if a given request should be handled by this server instance.
  *
- * @api public
+ * @param {http.IncomingMessage} req Request object to inspect
+ * @return {Boolean} `true` if the request is valid, else `false`
+ * @public
  */
-
-WebSocketServer.prototype.handleUpgrade = function (req, socket, upgradeHead, cb) {
-  // check for wrong path
-  if (this.options.path) {
-    var u = url.parse(req.url);
-    if (u && u.pathname !== this.options.path) {
-      return abortConnection(socket, 400);
-    }
+WebSocketServer.prototype.shouldHandle = function (req) {
+  if (this.options.path && url.parse(req.url).pathname !== this.options.path) {
+    return false;
   }
 
-  if (!req.headers.upgrade || req.headers.upgrade.toLowerCase() !== 'websocket') {
+  return true;
+};
+
+/**
+ * Handle a HTTP Upgrade request.
+ *
+ * @param {http.IncomingMessage} req The request object
+ * @param {net.Socket} socket The network socket between the server and client
+ * @param {Buffer} head The first packet of the upgraded stream
+ * @param {Function} cb Callback
+ * @public
+ */
+WebSocketServer.prototype.handleUpgrade = function (req, socket, head, cb) {
+  if (
+    !this.shouldHandle(req) ||
+    !req.headers.upgrade ||
+    req.headers.upgrade.toLowerCase() !== 'websocket'
+  ) {
     return abortConnection(socket, 400);
   }