rem: struct tcpcb *tcp_usrclosed(struct tcpcb *tp)
add: static struct tcpcb *tcp_usrclosed(struct tcpcb *tp)
context: struct tcpcb *tcp_usrclosed(struct tcpcb *tp){	switch(tp->t_state) {		case TCPS_CLOSED:		case TCPS_LISTEN:		case TCPS_SYN_SENT:			tp->t_state = TCPS_CLOSED;			tp = tcp_close(tp);			break;		case TCPS_SYN_RECEIVED:		case TCPS_ESTABLISHED:			tp->t_state = TCPS_FIN_WAIT_1;			break;		case TCPS_CLOSE_WAIT:			tp->t_state = TCPS_LAST_ACK;			break;	}	if (tp && tp->t_state >= TCPS_FIN_WAIT_2)		socket_set_disconnected(tp->t_inpcb->inp_socket);	return tp;}