GUAC-574: Synchronize across ActiveConnectionMap to prevent connection usage race conditions. Need to revisit architecture of connection management within MySQL.

extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/MySQLGuacamoleSocket.java

@@ -39,7 +39,7 @@ public class MySQLGuacamoleSocket implements GuacamoleSocket {
      * Injected ActiveConnectionMap which will contain all active connections.
      */
     @Inject
-    private ActiveConnectionMap activeConnectionSet;
+    private ActiveConnectionMap activeConnectionMap;
 
     /**
      * The wrapped socket.
@@ -67,7 +67,7 @@ public class MySQLGuacamoleSocket implements GuacamoleSocket {
      * @param connectionGroupID The ID of the balancing connection group that is
      *                          being connected to; null if not used.
      */
-    public void init(GuacamoleSocket socket, int connectionID, int userID, 
+    public void init(GuacamoleSocket socket,
             int historyID, Integer connectionGroupID) {
         this.socket = socket;
         this.historyID = historyID;
@@ -91,7 +91,10 @@ public class MySQLGuacamoleSocket implements GuacamoleSocket {
         socket.close();
 
         // Mark this connection as inactive
-        activeConnectionSet.closeConnection(historyID, connectionGroupID);
+        synchronized (activeConnectionMap) {
+            activeConnectionMap.closeConnection(historyID, connectionGroupID);
+        }
+
     }
 
     @Override

extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/service/ConnectionGroupService.java

@@ -176,7 +176,7 @@ public class ConnectionGroupService {
      * Connect to the connection within the given group with the lowest number
      * of currently active users.
      *
-     * @param connection The group to load balance across.
+     * @param group The group to load balance across.
      * @param info The information to use when performing the connection
      *             handshake.
      * @param userID The ID of the user who is connecting to the socket.
@@ -191,6 +191,8 @@ public class ConnectionGroupService {
         List<Integer> connectionIDs = connectionService.getAllConnectionIDs
                 (group.getConnectionGroupID());
         
+        synchronized (activeConnectionMap) {
+
             // Get the least used connection.
             Integer leastUsedConnectionID = 
                     activeConnectionMap.getLeastUsedConnection(connectionIDs);
@@ -216,6 +218,9 @@ public class ConnectionGroupService {
             
             // Connect to the connection
             return connectionService.connect(connection, info, userID, group.getConnectionGroupID());
+
+        }
+            
     }
     
     /**

extensions/guacamole-auth-mysql/src/main/java/net/sourceforge/guacamole/net/auth/mysql/service/ConnectionService.java

@@ -322,6 +322,8 @@ public class ConnectionService {
             GuacamoleClientInformation info, int userID, Integer connectionGroupID)
         throws GuacamoleException {
 
+        synchronized (activeConnectionMap) {
+
             // If the given connection is active, and multiple simultaneous
             // connections are not allowed, disallow connection
             if(GuacamoleProperties.getProperty(
@@ -358,13 +360,14 @@ public class ConnectionService {
 
                 // Return new MySQLGuacamoleSocket
             MySQLGuacamoleSocket mySQLGuacamoleSocket = mySQLGuacamoleSocketProvider.get();
-        mySQLGuacamoleSocket.init(socket, connection.getConnectionID(), userID, 
-                historyID, connectionGroupID);
+            mySQLGuacamoleSocket.init(socket, historyID, connectionGroupID);
                 
             return mySQLGuacamoleSocket;
 
         }
 
+    }
+
     /**
      * Creates a new connection having the given name and protocol.
      *