novnc: Accept new novnc client and disconnect old session (#4531)

* novnc: Reject new novnc client if novnc viewer object is still alive

* #4531 novnc: Accept new novnc client and disconnect old session

Author: ustcweizhou

services/console-proxy/server/src/main/java/com/cloud/consoleproxy/ConsoleProxy.java

@@ -551,11 +551,23 @@ public static ConsoleProxyNoVncClient getNoVncViewer(ConsoleProxyClientParam par
                         !param.getClientHostPassword().equals(viewer.getClientHostPassword()))
                     throw new AuthenticationException("Cannot use the existing viewer " + viewer + ": bad sid");
 
-                if (!viewer.isFrontEndAlive()) {
+                try {
                     authenticationExternally(param);
-                    viewer.initClient(param);
-                    reportLoadChange = true;
+                } catch (Exception e) {
+                    s_logger.error("Authencation failed for param: " + param);
+                    return null;
+                }
+                s_logger.info("Initializing new novnc client and disconnecting existing session");
+                try {
+                    ((ConsoleProxyNoVncClient)viewer).getSession().disconnect();
+                } catch (IOException e) {
+                    s_logger.error("Exception while disconnect session of novnc viewer object: " + viewer, e);
                 }
+                removeViewer(viewer);
+                viewer = new ConsoleProxyNoVncClient(session);
+                viewer.initClient(param);
+                connectionMap.put(clientKey, viewer);
+                reportLoadChange = true;
             }
 
             if (reportLoadChange) {

services/console-proxy/server/src/main/java/com/cloud/consoleproxy/ConsoleProxyNoVNCHandler.java

@@ -38,7 +38,7 @@
 @WebSocket
 public class ConsoleProxyNoVNCHandler extends WebSocketHandler {
 
-    private ConsoleProxyNoVncClient viewer;
+    private ConsoleProxyNoVncClient viewer = null;
     private static final Logger s_logger = Logger.getLogger(ConsoleProxyNoVNCHandler.class);
 
     public ConsoleProxyNoVNCHandler() {
@@ -130,12 +130,18 @@ public void onConnect(final Session session) throws IOException, InterruptedExce
         } catch (Exception e) {
             s_logger.warn("Failed to create viewer due to " + e.getMessage(), e);
             return;
+        } finally {
+            if (viewer == null) {
+                session.disconnect();
+            }
         }
     }
 
     @OnWebSocketClose
     public void onClose(Session session, int statusCode, String reason) throws IOException, InterruptedException {
-        ConsoleProxy.removeViewer(viewer);
+        if (viewer != null) {
+            ConsoleProxy.removeViewer(viewer);
+        }
     }
 
     @OnWebSocketFrame

services/console-proxy/server/src/main/java/com/cloud/consoleproxy/ConsoleProxyNoVncClient.java

@@ -235,4 +235,8 @@ public String getClientTag() {
         return "";
     }
 
+    public Session getSession() {
+        return session;
+    }
+
 }