Throw exceptions from RFB constructor

Previously, if an error was thrown from the Display constructor
in the RFB constructor, we would attempt to use `RFB#updateState`
to handle this.  However, `RFB#updateState` attempts to close
the WebSocket connection, which doesn't exist at this point.

In the constructor, it's probably just better to raise an exception
instead (making sure to clean up anything relevant).

Fixes #460

include/rfb.js

@@ -159,11 +159,13 @@ var RFB;
             this._encStats[this._encodings[i][1]] = [0, 0];
         }
 
+        // NB: nothing that needs explicit teardown should be done
+        // before this point, since this can throw an exception
         try {
             this._display = new Display({target: this._target});
         } catch (exc) {
             Util.Error("Display exception: " + exc);
-            this._updateState('fatal', "No working Display");
+            throw exc;
         }
 
         this._keyboard = new Keyboard({target: this._focusContainer,
@@ -217,9 +219,11 @@ var RFB;
         } else {
             Util.Warn("Using web-socket-js bridge.  Flash version: " + Util.Flash.version);
             if (!Util.Flash || Util.Flash.version < 9) {
-                this._updateState('fatal', "WebSockets or <a href='http://get.adobe.com/flashplayer'>Adobe Flash</a> is required");
+                this._cleanupSocket('fatal');
+                throw new Exception("WebSockets or <a href='http://get.adobe.com/flashplayer'>Adobe Flash</a> is required");
             } else if (document.location.href.substr(0, 7) === 'file://') {
-                this._updateState('fatal', "'file://' URL is incompatible with Adobe Flash");
+                this._cleanupSocket('fatal');
+                throw new Exception("'file://' URL is incompatible with Adobe Flash");
             } else {
                 this._updateState('loaded', 'noVNC ready: WebSockets emulation, ' + rmode);
             }
@@ -398,6 +402,32 @@ var RFB;
             }
         },
 
+        _cleanupSocket: function (state) {
+            if (this._sendTimer) {
+                clearInterval(this._sendTimer);
+                this._sendTimer = null;
+            }
+
+            if (this._msgTimer) {
+                clearInterval(this._msgTimer);
+                this._msgTimer = null;
+            }
+
+            if (this._display && this._display.get_context()) {
+                this._keyboard.ungrab();
+                this._mouse.ungrab();
+                if (state !== 'connect' && state !== 'loaded') {
+                    this._display.defaultCursor();
+                }
+                if (Util.get_logging() !== 'debug' || state === 'loaded') {
+                    // Show noVNC logo on load and when disconnected, unless in
+                    // debug mode
+                    this._display.clear();
+                }
+            }
+
+            this._sock.close();
+        },
 
         /*
          * Page states:
@@ -432,31 +462,7 @@ var RFB;
              */
             if (state in {'disconnected': 1, 'loaded': 1, 'connect': 1,
                           'disconnect': 1, 'failed': 1, 'fatal': 1}) {
-
-                if (this._sendTimer) {
-                    clearInterval(this._sendTimer);
-                    this._sendTimer = null;
-                }
-
-                if (this._msgTimer) {
-                    clearInterval(this._msgTimer);
-                    this._msgTimer = null;
-                }
-
-                if (this._display && this._display.get_context()) {
-                    this._keyboard.ungrab();
-                    this._mouse.ungrab();
-                    if (state !== 'connect' && state !== 'loaded') {
-                        this._display.defaultCursor();
-                    }
-                    if (Util.get_logging() !== 'debug' || state === 'loaded') {
-                        // Show noVNC logo on load and when disconnected, unless in
-                        // debug mode
-                        this._display.clear();
-                    }
-                }
-
-                this._sock.close();
+                this._cleanupSocket(state);
             }
 
             if (oldstate === 'fatal') {

include/ui.js

@@ -159,6 +159,7 @@ var UI;
         },
 
         initRFB: function () {
+            try {
                 UI.rfb = new RFB({'target': $D('noVNC_canvas'),
                                   'onUpdateState': UI.updateState,
                                   'onXvpInit': UI.updateXvpVisualState,
@@ -166,6 +167,11 @@ var UI;
                                   'onFBUComplete': UI.FBUComplete,
                                   'onFBResize': UI.updateViewDragButton,
                                   'onDesktopName': UI.updateDocumentTitle});
+                return true;
+            } catch (exc) {
+                UI.updateState(null, 'fatal', null, 'Unable to create RFB client -- ' + exc);
+                return false;
+            }
         },
 
         addMouseHandlers: function() {
@@ -772,7 +778,7 @@ var UI;
                 throw new Error("Must set host and port");
             }
 
-            UI.initRFB();
+            if (!UI.initRFB()) return;
 
             UI.rfb.set_encrypt(UI.getSetting('encrypt'));
             UI.rfb.set_true_color(UI.getSetting('true_color'));

vnc_auto.html

@@ -216,6 +216,7 @@
                 return;
             }
 
+            try {
                 rfb = new RFB({'target':       $D('noVNC_canvas'),
                                'encrypt':      WebUtil.getQueryVar('encrypt',
                                         (window.location.protocol === "https:")),
@@ -228,6 +229,11 @@
                                'onXvpInit':    xvpInit,
                                'onPasswordRequired':  passwordRequired,
                                'onFBUComplete': FBUComplete});
+            } catch (exc) {
+                UI.updateState(null, 'fatal', null, 'Unable to create RFB client -- ' + exc);
+                return; // don't continue trying to connect
+            }
+
             rfb.connect(host, port, password, path);
         };
         </script>