output: #fixed code
                                  protected void handleConnect(IoSession session, ConnectMessage msg) {
          LOG.info("handleConnect invoked");
  
          m_messaging.connect(session, msg);
      }
input: #vulnerable code 
                                  protected void handleConnect(IoSession session, ConnectMessage msg) {
          LOG.info("handleConnect invoked");
          if (msg.getProcotolVersion() != 0x03) {
              ConnAckMessage badProto = new ConnAckMessage();
              badProto.setReturnCode(ConnAckMessage.UNNACEPTABLE_PROTOCOL_VERSION);
              session.write(badProto);
              session.close(false);
              return;
          }
  
          if (msg.getClientID() == null || msg.getClientID().length() > 23) {
              ConnAckMessage okResp = new ConnAckMessage();
              okResp.setReturnCode(ConnAckMessage.IDENTIFIER_REJECTED);
              session.write(okResp);
              return;
          }
  
          m_clientIDsLock.lock();
          try {
              //if an old client with the same ID already exists close its session.
              if (m_clientIDs.containsKey(msg.getClientID())) {
                  //clean the subscriptions if the old used a cleanSession = true
                  IoSession oldSession = m_clientIDs.get(msg.getClientID()).getSession();
                  boolean cleanSession = (Boolean) oldSession.getAttribute(Constants.CLEAN_SESSION);
                  if (cleanSession) {
                      //cleanup topic subscriptions
                      m_messaging.removeSubscriptions(msg.getClientID());
                  }
  
                  m_clientIDs.get(msg.getClientID()).getSession().close(false);
              }
  
              ConnectionDescriptor connDescr = new ConnectionDescriptor(msg.getClientID(), session, msg.isCleanSession());
              m_clientIDs.put(msg.getClientID(), connDescr);
          } finally {
              m_clientIDsLock.unlock();
          }
  
          int keepAlive = msg.getKeepAlive();
          session.setAttribute("keepAlive", keepAlive);
          session.setAttribute(Constants.CLEAN_SESSION, msg.isCleanSession());
          //used to track the client in the subscription and publishing phases. 
          session.setAttribute(Constants.ATTR_CLIENTID, msg.getClientID());
  
          session.getConfig().setIdleTime(IdleStatus.READER_IDLE, Math.round(keepAlive * 1.5f));
  
          //Handle will flag
          if (msg.isWillFlag()) {
              QOSType willQos = QOSType.values()[msg.getWillQos()];
              m_messaging.publish(msg.getWillTopic(), msg.getWillMessage().getBytes(),
                      willQos, msg.isWillRetain(), msg.getClientID(), session);
          }
  
          //handle user authentication
          if (msg.isUserFlag()) {
              String pwd = null;
              if (msg.isPasswordFlag()) {
                  pwd = msg.getPassword();
              }
              if (!m_authenticator.checkValid(msg.getUsername(), pwd)) {
                  ConnAckMessage okResp = new ConnAckMessage();
                  okResp.setReturnCode(ConnAckMessage.BAD_USERNAME_OR_PASSWORD);
                  session.write(okResp);
                  return;
              }
          }
  
          //handle clean session flag
          if (msg.isCleanSession()) {
              //remove all prev subscriptions
              //cleanup topic subscriptions
              m_messaging.removeSubscriptions(msg.getClientID());
          }  else {
              //force the republish of stored QoS1 and QoS2
              m_messaging.republishStored(msg.getClientID());
          }
  
          ConnAckMessage okResp = new ConnAckMessage();
          okResp.setReturnCode(ConnAckMessage.CONNECTION_ACCEPTED);
          session.write(okResp);
      } 
                              #location 75 
                              #vulnerability type THREAD_SAFETY_VIOLATION