Merge pull request #250 from imkira/allowCustomSessionIds

Allow custom session ids

Author: brycekahle

README.md

@@ -127,6 +127,17 @@ Where `options` is a hash which can contain:
     option allows you to supply a list transports that may be used by
     SockJS. By default all available transports will be used.
 
+ *  **sessionId (number OR function)**
+
+    Both client and server use session identifiers to distinguish connections.
+    If you specify this option as a number, SockJS will use its random string
+    generator function to generate session ids that are N-character long
+    (where N corresponds to the number specified by **sessionId**).
+    When you specify this option as a function, the function must return a
+    randomly generated string. Every time SockJS needs to generate a session
+    id it will call this function and use the returned string directly.
+    If you don't specify this option, the default is to use the default random
+    string generator to generate 8-character long session ids.
 
 Although the 'SockJS' object tries to emulate the 'WebSocket'
 behaviour, it's impossible to support all of its features. An

lib/main.js

@@ -50,6 +50,18 @@ function SockJS(url, protocols, options) {
     log.warn("'protocols_whitelist' is DEPRECATED. Use 'transports' instead.");
   }
   this._transportsWhitelist = options.transports;
+
+  var sessionId = options.sessionId || 8;
+  if (typeof sessionId === 'function') {
+    this._generateSessionId = sessionId;
+  } else if (typeof sessionId === 'number') {
+    this._generateSessionId = function() {
+      return random.string(sessionId);
+    }
+  } else {
+    throw new TypeError("If sessionId is used in the options, it needs to be a number or a function.");
+  }
+
   this._server = options.server || random.numberString(1000);
 
   // Step 1 of WS spec - parse and validate the url. Issue #8
@@ -202,7 +214,7 @@ SockJS.prototype._connect = function() {
     this._transportTimeoutId = setTimeout(this._transportTimeout.bind(this), timeoutMs);
     debug('using timeout', timeoutMs);
 
-    var transportUrl = urlUtils.addPath(this._transUrl, '/' + this._server + '/' + random.string(8));
+    var transportUrl = urlUtils.addPath(this._transUrl, '/' + this._server + '/' + this._generateSessionId());
     debug('transport url', transportUrl);
     var transportObj = new Transport(transportUrl, this._transUrl);
     transportObj.on('message', this._transportMessage.bind(this));

tests/lib/main.js

@@ -70,5 +70,36 @@ describe('SockJS', function() {
         });
       });
     });
+
+    it('should generate 8-character-long session ids by default', function () {
+      var s = SockJS('http://localhost');
+      expect(s._generateSessionId().length).to.be(8);
+      s.close();
+    });
+
+    it('should generate N-character-long session ids', function () {
+      for (var i = 1; i <= 100; i++) {
+        var s = SockJS('http://localhost', null, {sessionId: i});
+        expect(s._generateSessionId().length).to.be(i);
+        s.close();
+      }
+    });
+
+    it('should generate sessionIds using the custom generator function', function () {
+      var f = function() {
+        return 'this_is_not_random';
+      };
+      var s = SockJS('http://localhost', null, {sessionId: f});
+      expect(s._generateSessionId).to.be(f);
+      s.close();
+    });
+
+    it('should throw TypeError if sessionId is neither a number nor a function', function () {
+        expect(function () {
+          new SockJS('http://localhost', null, {sessionId: 'this is wrong'});
+        }).to.throwException(function (e) {
+          expect(e).to.be.a(TypeError);
+        });
+    });
   });
 });