tcp_server:

  class tcp_server: public csserver
  {
  public:
      tcp_server();
      tcp_server(int portnr);
      virtual ~tcp_server();
  
      virtual int portnr() const; // returns port at which server is listening
  
  protected:
      tcp_serverimp* _tcpimp;
      inet_address* _tcpaddr;
  };