code: def _match_host_port(self, host, port, cur_host, cur_port):
      
      # if host is '', true;  if not '', it should prefix-match cur_host
      host_match = False
      if not host:
        host_match = True
      elif cur_host.startswith(host):  # allow for partial match
        host_match = True
  
      # if port is '', true;  if not '', it should exactly match cur_port
      port_match = False
      if not port:
        port_match = True
      elif port == cur_port:
        port_match = True
  
      return host_match and port_match
docs: Determine whether user-specified (host,port) matches current (cur_host, cur_port)
      :param host,port: The user input of (host,port)
      :param cur_host, cur_port: The current connection
      :return: True or Not