llc_subr.c

早期freebsd实现

		break;
	case NL_DISCONNECT_REQUEST:
		if (LLC_GETFLAG(linkp, S) == 0) {
			llc_send(linkp, LLCFT_DISC, LLC_CMD, pollfinal);
			LLC_SETFLAG(linkp, P, pollfinal);
			LLC_START_ACK_TIMER(linkp);
			linkp->llcl_retry = 0;
			LLC_NEWSTATE(linkp, D_CONN);
		} else {
			llc_send(linkp, LLCFT_DM, LLC_RSP, 
				      LLC_GETFLAG(linkp, F));
			LLC_NEWSTATE(linkp, ADM);
		}
		break;
	case LLCFT_DM + LLC_RSP:
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	case LLCFT_SABME + LLC_CMD:
		LLC_SETFLAG(linkp, S, 1);
		LLC_SETFLAG(linkp, F, pollfinal);
		break;
	case LLCFT_DISC + LLC_CMD:
		llc_send(linkp, LLCFT_DM, LLC_RSP, pollfinal);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	}

	return action;
}

/*
 * RESET_CHECK --- The local connection component is waiting for the local user
 *                 to accept or refuse a remote reset request.
 */
int
llc_state_RESET_CHECK(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		      int cmdrsp, int pollfinal)
{
	int action = 0;

	switch(frame_kind + cmdrsp) {
	case NL_RESET_RESPONSE:
		llc_send(linkp, LLCFT_UA, LLC_RSP, LLC_GETFLAG(linkp, F));
		LLC_RESETCOUNTER(linkp);
		LLC_SETFLAG(linkp, P, 0);
		LLC_SETFLAG(linkp, REMOTE_BUSY, 0);
		LLC_NEWSTATE(linkp, NORMAL);
		break;
	case NL_DISCONNECT_REQUEST:
		llc_send(linkp, LLCFT_DM, LLC_RSP, LLC_GETFLAG(linkp, F));
		LLC_NEWSTATE(linkp, ADM);
		break;
	case LLCFT_DM + LLC_RSP:
		action = LLC_DISCONNECT_INDICATION;
		break;
	case LLCFT_SABME + LLC_CMD:
		LLC_SETFLAG(linkp, F, pollfinal);
		break;
	case LLCFT_DISC + LLC_CMD:
		llc_send(linkp, LLCFT_DM, LLC_RSP, pollfinal);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	}

	return action;
}

/*
 * SETUP --- The connection component has transmitted an SABME command PDU to a
 *           remote LLC DSAP and is waiting for a reply.
 */
int
llc_state_SETUP(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		int cmdrsp, int pollfinal)
{
	int action = 0;

	switch(frame_kind + cmdrsp) {
	case LLCFT_SABME + LLC_CMD:
		LLC_RESETCOUNTER(linkp);
		llc_send(linkp, LLCFT_UA, LLC_RSP, pollfinal);
		LLC_SETFLAG(linkp, S, 1);
		break;
	case LLCFT_UA + LLC_RSP:
		if (LLC_GETFLAG(linkp, P) == pollfinal) {
			LLC_STOP_ACK_TIMER(linkp);
			LLC_RESETCOUNTER(linkp);
			LLC_UPDATE_P_FLAG(linkp, cmdrsp, pollfinal);
			LLC_SETFLAG(linkp, REMOTE_BUSY, 0);
			LLC_NEWSTATE(linkp, NORMAL);
			action = LLC_CONNECT_CONFIRM;
		}
		break;
	case LLC_ACK_TIMER_EXPIRED:
		if (LLC_GETFLAG(linkp, S) == 1) {
			LLC_SETFLAG(linkp, P, 0);
			LLC_SETFLAG(linkp, REMOTE_BUSY, 0),
			LLC_NEWSTATE(linkp, NORMAL);
			action = LLC_CONNECT_CONFIRM;
		} else if (linkp->llcl_retry < llc_n2) {
			llc_send(linkp, LLCFT_SABME, LLC_CMD, pollfinal);
			LLC_SETFLAG(linkp, P, pollfinal);
			LLC_START_ACK_TIMER(linkp);
			linkp->llcl_retry++;
		} else {
			LLC_NEWSTATE(linkp, ADM);
			action = LLC_DISCONNECT_INDICATION;
		}
		break;
	case LLCFT_DISC + LLC_CMD:
		llc_send(linkp, LLCFT_DM, LLC_RSP, pollfinal);
		LLC_STOP_ACK_TIMER(linkp);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	case LLCFT_DM + LLC_RSP:
		LLC_STOP_ACK_TIMER(linkp);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	}

	return action;
}

/*
 * RESET --- As a result of a service access point user request or the receipt
 *           of a FRMR response PDU, the local connection component has sent an
 *           SABME command PDU to the remote LLC DSAP to reset the data link
 *           connection and is waiting for a reply.
 */
int
llc_state_RESET(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		int cmdrsp, int pollfinal)
{
	int action = 0;

	switch(frame_kind + cmdrsp) {
	case LLCFT_SABME + LLC_CMD:
		LLC_RESETCOUNTER(linkp);
		LLC_SETFLAG(linkp, S, 1);
		llc_send(linkp, LLCFT_UA, LLC_RSP, pollfinal);
		break;
	case LLCFT_UA + LLC_RSP:
		if (LLC_GETFLAG(linkp, P) == pollfinal) {
			LLC_STOP_ACK_TIMER(linkp);
			LLC_RESETCOUNTER(linkp);
			LLC_UPDATE_P_FLAG(linkp, cmdrsp, pollfinal);
			LLC_SETFLAG(linkp, REMOTE_BUSY, 0);
			LLC_NEWSTATE(linkp, NORMAL);
			action = LLC_RESET_CONFIRM;
		}
		break;
	case LLC_ACK_TIMER_EXPIRED:
		if (LLC_GETFLAG(linkp, S) == 1) {
			LLC_SETFLAG(linkp, P, 0);
			LLC_SETFLAG(linkp, REMOTE_BUSY, 0);
			LLC_NEWSTATE(linkp, NORMAL);
			action = LLC_RESET_CONFIRM;
		} else if (linkp->llcl_retry < llc_n2) {
			llc_send(linkp, LLCFT_SABME, LLC_CMD, pollfinal);
			LLC_SETFLAG(linkp, P, pollfinal);
			LLC_START_ACK_TIMER(linkp);
			linkp->llcl_retry++;
		} else {
			LLC_NEWSTATE(linkp, ADM);
			action = LLC_DISCONNECT_INDICATION;
		}
		break;
	case LLCFT_DISC + LLC_CMD:
		llc_send(linkp, LLCFT_DM, LLC_RSP, pollfinal);
		LLC_STOP_ACK_TIMER(linkp);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	case LLCFT_DM + LLC_RSP:
		LLC_STOP_ACK_TIMER(linkp);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	}

	return action;
}

/*
 * D_CONN --- At the request of the service access point user, the local LLC
 *            has sent a DISC command PDU to the remote LLC DSAP and is waiting
 *            for a reply.
 */
int
llc_state_D_CONN(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		 int cmdrsp, int pollfinal)
{
	int action = 0;

	switch(frame_kind + cmdrsp) {
	case LLCFT_SABME + LLC_CMD:
		llc_send(linkp, LLCFT_DM, LLC_RSP, pollfinal);
		LLC_STOP_ACK_TIMER(linkp);
		LLC_NEWSTATE(linkp, ADM);
		break;
	case LLCFT_UA + LLC_RSP:
		if (LLC_GETFLAG(linkp, P) == pollfinal) {
			LLC_STOP_ACK_TIMER(linkp);
			LLC_NEWSTATE(linkp, ADM);
		}
		break;
	case LLCFT_DISC + LLC_CMD:
		llc_send(linkp, LLCFT_UA, LLC_RSP, pollfinal);
		break;
	case LLCFT_DM + LLC_RSP:
		LLC_STOP_ACK_TIMER(linkp);
		LLC_NEWSTATE(linkp, ADM);
		break;
	case LLC_ACK_TIMER_EXPIRED:
		if (linkp->llcl_retry < llc_n2) {
			llc_send(linkp, LLCFT_DISC, LLC_CMD, pollfinal);
			LLC_SETFLAG(linkp, P, pollfinal);
			LLC_START_ACK_TIMER(linkp);
			linkp->llcl_retry++;
		} else LLC_NEWSTATE(linkp, ADM);
		break;
	}

	return action;
}

/*
 * ERROR --- The local connection component has detected an error in a received
 *           PDU and has sent a FRMR response PDU. It is waiting for a reply from 
 *           the remote connection component.
 */
int
llc_state_ERROR(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		int cmdrsp, int pollfinal)
{
	int action = 0;

	switch(frame_kind + cmdrsp) {
	case LLCFT_SABME + LLC_CMD:
		LLC_STOP_ACK_TIMER(linkp);
		LLC_NEWSTATE(linkp, RESET_CHECK);
		action = LLC_RESET_INDICATION_REMOTE;
		break;
	case LLCFT_DISC + LLC_CMD:
		llc_send(linkp, LLCFT_UA, LLC_RSP, pollfinal);
		LLC_STOP_ACK_TIMER(linkp);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	case LLCFT_DM + LLC_RSP:
		LLC_STOP_ACK_TIMER(linkp);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	case LLCFT_FRMR + LLC_RSP:
		LLC_STOP_ACK_TIMER(linkp);
		LLC_SETFLAG(linkp, S, 0);
		LLC_NEWSTATE(linkp, RESET_WAIT);
		action = LLC_FRMR_RECEIVED;
		break;
	case LLC_ACK_TIMER_EXPIRED:
		if (linkp->llcl_retry < llc_n2) {
			llc_send(linkp, LLCFT_FRMR, LLC_RSP, 0);
			LLC_START_ACK_TIMER(linkp);
			linkp->llcl_retry++;
		} else {
			LLC_SETFLAG(linkp, S, 0);
			LLC_NEWSTATE(linkp, RESET_WAIT);
			action = LLC_RESET_INDICATION_LOCAL;
		}
		break;
	default:
		if (cmdrsp == LLC_CMD){
			llc_send(linkp, LLCFT_FRMR, LLC_RSP, pollfinal);
			LLC_START_ACK_TIMER(linkp);
		}
		break;

	}

	return action;
}

/*
 * NORMAL, BUSY, REJECT, AWAIT, AWAIT_BUSY, and AWAIT_REJECT all share
 * a common core state handler.
 */
int
llc_state_NBRAcore(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		   int cmdrsp, int pollfinal)
{
	int action = 0;

	switch(frame_kind + cmdrsp) {
	case NL_DISCONNECT_REQUEST:
		llc_send(linkp, LLCFT_DISC, LLC_CMD, pollfinal);
		LLC_SETFLAG(linkp, P, pollfinal);
		LLC_STOP_ALL_TIMERS(linkp);
		LLC_START_ACK_TIMER(linkp);
		linkp->llcl_retry = 0;
		LLC_NEWSTATE(linkp, D_CONN);
		break;
	case NL_RESET_REQUEST:
		llc_send(linkp, LLCFT_SABME, LLC_CMD, pollfinal);
		LLC_SETFLAG(linkp, P, pollfinal);
		LLC_STOP_ALL_TIMERS(linkp);
		LLC_START_ACK_TIMER(linkp);
		linkp->llcl_retry = 0;
		LLC_SETFLAG(linkp, S, 0);
		LLC_NEWSTATE(linkp, RESET);
		break;
	case LLCFT_SABME + LLC_CMD:
		LLC_SETFLAG(linkp, F, pollfinal);
		LLC_STOP_ALL_TIMERS(linkp);
		LLC_NEWSTATE(linkp, RESET_CHECK);
		action = LLC_RESET_INDICATION_REMOTE;
		break;
	case LLCFT_DISC + LLC_CMD:
		llc_send(linkp, LLCFT_UA, LLC_RSP, pollfinal);
		LLC_STOP_ALL_TIMERS(linkp);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	case LLCFT_FRMR + LLC_RSP:
		LLC_STOP_ALL_TIMERS(linkp);
		LLC_SETFLAG(linkp, S, 0);
		LLC_NEWSTATE(linkp, RESET_WAIT);
		action =  LLC_FRMR_RECEIVED;
		break;
	case LLCFT_DM + LLC_RSP:
		LLC_STOP_ALL_TIMERS(linkp);
		LLC_NEWSTATE(linkp, ADM);
		action = LLC_DISCONNECT_INDICATION;
		break;
	case LLC_INVALID_NR + LLC_CMD:
	case LLC_INVALID_NS + LLC_CMD:
		LLC_SETFRMR(linkp, frame, cmdrsp, 
			 (frame_kind == LLC_INVALID_NR ? LLC_FRMR_Z :
			  (LLC_FRMR_V | LLC_FRMR_W)));
		llc_send(linkp, LLCFT_FRMR, LLC_RSP, pollfinal);
		LLC_STOP_ALL_TIMERS(linkp);
		LLC_START_ACK_TIMER(linkp);
		linkp->llcl_retry = 0;
		LLC_NEWSTATE(linkp, ERROR);
		action = LLC_FRMR_SENT;
		break;
	case LLC_INVALID_NR + LLC_RSP:
	case LLC_INVALID_NS + LLC_RSP:
	case LLCFT_UA + LLC_RSP:
	case LLC_BAD_PDU: {
		char frmrcause = 0;

		switch (frame_kind) {
		case LLC_INVALID_NR: frmrcause = LLC_FRMR_Z; break;
		case LLC_INVALID_NS: frmrcause = LLC_FRMR_V | LLC_FRMR_W; break;
		default: frmrcause = LLC_FRMR_W;
		}
		LLC_SETFRMR(linkp, frame, cmdrsp, frmrcause);
		llc_send(linkp, LLCFT_FRMR, LLC_RSP, 0);
		LLC_STOP_ALL_TIMERS(linkp);
		LLC_START_ACK_TIMER(linkp);
		linkp->llcl_retry = 0;
		LLC_NEWSTATE(linkp, ERROR);
		action = LLC_FRMR_SENT;
		break;
	}
	default:
		if (cmdrsp == LLC_RSP && pollfinal == 1 && 
		    LLC_GETFLAG(linkp, P) == 0) {
			LLC_SETFRMR(linkp, frame, cmdrsp, LLC_FRMR_W);
			LLC_STOP_ALL_TIMERS(linkp);
			LLC_START_ACK_TIMER(linkp);
			linkp->llcl_retry = 0;
			LLC_NEWSTATE(linkp, ERROR);
			action = LLC_FRMR_SENT;
		}
		break;
	case LLC_P_TIMER_EXPIRED:
	case LLC_ACK_TIMER_EXPIRED:
	case LLC_REJ_TIMER_EXPIRED:
	case LLC_BUSY_TIMER_EXPIRED:
		if (linkp->llcl_retry >= llc_n2) {
			LLC_STOP_ALL_TIMERS(linkp);
			LLC_SETFLAG(linkp, S, 0);
			LLC_NEWSTATE(linkp, RESET_WAIT);
			action = LLC_RESET_INDICATION_LOCAL;
		}
		break;
	}

	return action;
}

/*
 * NORMAL --- A data link connection exists between the local LLC service access
 *            point and the remote LLC service access point. Sending and
 *            reception of information and supervisory PDUs can be performed.
 */
int
llc_state_NORMAL(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		 int cmdrsp, int pollfinal)
{
	int action = LLC_PASSITON;

	switch(frame_kind + cmdrsp) {
	case NL_DATA_REQUEST:
		if (LLC_GETFLAG(linkp, REMOTE_BUSY) == 0) {
#ifdef not_now
			if (LLC_GETFLAG(linkp, P) == 0) {
				/* multiple possibilities */
				llc_send(linkp, LLCFT_INFO, LLC_CMD, 1);
				LLC_START_P_TIMER(linkp);
				if (LLC_TIMERXPIRED(linkp, ACK) != LLC_TIMER_RUNNING)
					LLC_START_ACK_TIMER(linkp);
			} else {
#endif 
				/* multiple possibilities */
				llc_send(linkp, LLCFT_INFO, LLC_CMD, 0);
				if (LLC_TIMERXPIRED(linkp, ACK) != LLC_TIMER_RUNNING)
					LLC_START_ACK_TIMER(linkp);
#ifdef not_now
			}
#endif
			action = 0;
		}
		break;
	case LLC_LOCAL_BUSY_DETECTED:
		if (LLC_GETFLAG(linkp, P) == 0) {
			/* multiple possibilities --- action-wise */
			/* multiple possibilities --- CMD/RSP-wise */
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 0);
			LLC_START_P_TIMER(linkp);
			LLC_SETFLAG(linkp, DATA, 0);
			LLC_NEWSTATE(linkp, BUSY);
			action = 0;
		} else { 
			/* multiple possibilities --- CMD/RSP-wise */
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 0);
			LLC_SETFLAG(linkp, DATA, 0);
			LLC_NEWSTATE(linkp, BUSY);
			action = 0;			
		}
		break;
	case LLC_INVALID_NS + LLC_CMD:
	case LLC_INVALID_NS + LLC_RSP: {