docs: public void doFilter(ServletRequest request, ServletResponse response,
  			FilterChain chain) throws IOException, ServletException {
  		int localPort = request.getLocalPort();
  		if (mode == MODE_ALLOW && !portHit(localPort) ||
  				mode == MODE_DENY && portHit(localPort)){
  			if (message == null){
  				((HttpServletResponse) response).sendError(statusCode, ((HttpServletRequest)request).getRequestURI());
  			}else if (message.length() == 0){
  				((HttpServletResponse) response).sendError(statusCode);
  			}else{
  				((HttpServletResponse) response).sendError(statusCode, message);
  			}
  		}else{
  			chain.doFilter(request, response);
  		}
  	}