llc_subr.c

早期freebsd实现

		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);

		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			llc_send(linkp, LLCFT_REJ, LLC_RSP, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_START_REJ_TIMER(linkp);
			LLC_NEWSTATE(linkp, REJECT);
			action = 0;
		} else if (pollfinal == 0 && p == 1) {
			llc_send(linkp, LLCFT_REJ, LLC_CMD, 0);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_START_REJ_TIMER(linkp);
			LLC_NEWSTATE(linkp, REJECT);
			action = 0;
		} else if ((pollfinal == 0 && p == 0) || 
			   (pollfinal == 1 && p == 1 && cmdrsp == LLC_RSP)) {
			llc_send(linkp, LLCFT_REJ, LLC_CMD, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_START_P_TIMER(linkp);
			LLC_START_REJ_TIMER(linkp);
			if (cmdrsp == LLC_RSP && pollfinal == 1) {
				LLC_CLEAR_REMOTE_BUSY(linkp, action);
			} else action = 0;
			LLC_NEWSTATE(linkp, REJECT);
		}
		break;
	} 
	case LLCFT_INFO + LLC_CMD:
	case LLCFT_INFO + LLC_RSP: {
		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);
		
		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			LLC_INC(linkp->llcl_vr);
			LLC_SENDACKNOWLEDGE(linkp, LLC_RSP, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			action = LLC_DATA_INDICATION;
		} else if (pollfinal == 0 && p == 1) {
			LLC_INC(linkp->llcl_vr);
			LLC_SENDACKNOWLEDGE(linkp, LLC_CMD, 0);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			action = LLC_DATA_INDICATION;
		} else if ((pollfinal == 0 && p == 0 && cmdrsp == LLC_CMD) ||
			   (pollfinal == p && cmdrsp == LLC_RSP)) {
			LLC_INC(linkp->llcl_vr);
			LLC_UPDATE_P_FLAG(linkp, cmdrsp, pollfinal);
			LLC_SENDACKNOWLEDGE(linkp, LLC_CMD, 0);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			if (cmdrsp == LLC_RSP && pollfinal == 1) 
				LLC_CLEAR_REMOTE_BUSY(linkp, action);
			action = LLC_DATA_INDICATION;
		}
		break;
	}
	case LLCFT_RR + LLC_CMD:
	case LLCFT_RR + LLC_RSP: {
		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);

		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			LLC_SENDACKNOWLEDGE(linkp, LLC_RSP, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
		} else if ((pollfinal == 0) || 
			   (cmdrsp == LLC_RSP && pollfinal == 1 && p == 1)) {
			LLC_UPDATE_P_FLAG(linkp, cmdrsp, pollfinal);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
		} 
		break;
	}
	case LLCFT_RNR + LLC_CMD:
	case LLCFT_RNR + LLC_RSP: {
		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);
		
		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			llc_send(linkp, LLCFT_RR, LLC_RSP, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_SET_REMOTE_BUSY(linkp, action);
		} else if ((pollfinal == 0) || 
			   (cmdrsp == LLC_RSP && pollfinal == 1 && p == 1)) {
			LLC_UPDATE_P_FLAG(linkp, cmdrsp, pollfinal);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_SET_REMOTE_BUSY(linkp, action);
		}
		break;
	}
	case LLCFT_REJ + LLC_CMD:
	case LLCFT_REJ + LLC_RSP: {
		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);

		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			linkp->llcl_vs = nr;
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			llc_resend(linkp, LLC_RSP, 1);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
		} else if (pollfinal == 0 && p == 1) {
			linkp->llcl_vs = nr;
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			llc_resend(linkp, LLC_CMD, 0);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
		} else if ((pollfinal == 0 && p == 0 && cmdrsp == LLC_CMD) ||
			   (pollfinal == p && cmdrsp == LLC_RSP)) {
			linkp->llcl_vs = nr;
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_START_P_TIMER(linkp);
			llc_resend(linkp, LLC_CMD, 1);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
		}
		break;
	}
	case NL_INITIATE_PF_CYCLE:
		if (LLC_GETFLAG(linkp, P) == 0) {
			llc_send(linkp, LLCFT_RR, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			action = 0;
		}
		break;
	case LLC_P_TIMER_EXPIRED:
		if (linkp->llcl_retry < llc_n2) {
			llc_send(linkp, LLCFT_RR, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			linkp->llcl_retry++;
			LLC_NEWSTATE(linkp, AWAIT);
			action = 0;
		}
		break;
	case LLC_ACK_TIMER_EXPIRED:
	case LLC_BUSY_TIMER_EXPIRED:
		if ((LLC_GETFLAG(linkp, P) == 0) 
		    && (linkp->llcl_retry < llc_n2)) {
			llc_send(linkp, LLCFT_RR, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			linkp->llcl_retry++;
			LLC_NEWSTATE(linkp, AWAIT);
			action = 0;
		}
		break;
	}
	if (action == LLC_PASSITON)
		action = llc_state_NBRAcore(linkp, frame, frame_kind, 
					    cmdrsp, pollfinal);

	return action;
}

/*
 * BUSY --- A data link connection exists between the local LLC service access
 *          point and the remote LLC service access point. I PDUs may be sent.
 *          Local conditions make it likely that the information feld of
 *          received I PDUs will be ignored. Supervisory PDUs may be both sent
 *          and received.
 */
int
llc_state_BUSY(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)
			if (LLC_GETFLAG(linkp, P) == 0) {
				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);
				action = 0;
			} else {
				llc_send(linkp, LLCFT_INFO, LLC_CMD, 0);
				if (LLC_TIMERXPIRED(linkp, ACK) != LLC_TIMER_RUNNING)
					LLC_START_ACK_TIMER(linkp);
				action = 0;
			}
		break;
	case LLC_LOCAL_BUSY_CLEARED: {
		register int p = LLC_GETFLAG(linkp, P);
		register int df = LLC_GETFLAG(linkp, DATA);

		switch (df) {
		case 1: 
			if (p == 0) {
				/* multiple possibilities */
				llc_send(linkp, LLCFT_REJ, LLC_CMD, 1);
				LLC_START_REJ_TIMER(linkp);
				LLC_START_P_TIMER(linkp);
				LLC_NEWSTATE(linkp, REJECT);
				action = 0;
			} else {
				llc_send(linkp, LLCFT_REJ, LLC_CMD, 0);
				LLC_START_REJ_TIMER(linkp);
				LLC_NEWSTATE(linkp, REJECT);
				action = 0;
			}
			break;
		case 0:
			if (p == 0) {
				/* multiple possibilities */
				llc_send(linkp, LLCFT_RR, LLC_CMD, 1);
				LLC_START_P_TIMER(linkp);
				LLC_NEWSTATE(linkp, NORMAL);
				action = 0;
			} else {
				llc_send(linkp, LLCFT_RR, LLC_CMD, 0);
				LLC_NEWSTATE(linkp, NORMAL);
				action = 0;
			}
			break;
		case 2:
			if (p == 0) {
				/* multiple possibilities */
				llc_send(linkp, LLCFT_RR, LLC_CMD, 1);
				LLC_START_P_TIMER(linkp);
				LLC_NEWSTATE(linkp, REJECT);
				action = 0;
			} else {
				llc_send(linkp, LLCFT_RR, LLC_CMD, 0);
				LLC_NEWSTATE(linkp, REJECT);
				action =0;
			}
			break;
		}
		break;
	}
	case LLC_INVALID_NS + LLC_CMD:
	case LLC_INVALID_NS + LLC_RSP: {
		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);

		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			llc_send(linkp, LLCFT_RNR, LLC_RSP, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			if (LLC_GETFLAG(linkp, DATA) == 0)
				LLC_SETFLAG(linkp, DATA, 1);
			action = 0;
		} else if ((cmdrsp == LLC_CMD && pollfinal == 0 && p == 0) ||
			   (cmdrsp == LLC_RSP && pollfinal == p)) {
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 0);
			LLC_UPDATE_P_FLAG(linkp, cmdrsp, pollfinal);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			if (LLC_GETFLAG(linkp, DATA) == 0) 
				LLC_SETFLAG(linkp, DATA, 1);
			if (cmdrsp == LLC_RSP && pollfinal == 1) {
				LLC_CLEAR_REMOTE_BUSY(linkp, action);
			} else action = 0;
		} else if (pollfinal == 0 && p == 1) {
			llc_send(linkp, LLCFT_RNR, LLC_RSP, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			if (LLC_GETFLAG(linkp, DATA) == 0)
				LLC_SETFLAG(linkp, DATA, 1);
			action = 0;
		}
		break;
	}
	case LLCFT_INFO + LLC_CMD:
	case LLCFT_INFO + LLC_RSP: {
		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);
		
		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			LLC_INC(linkp->llcl_vr);
			llc_send(linkp, LLCFT_RNR, LLC_RSP, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			if (LLC_GETFLAG(linkp, DATA) == 2)
				LLC_STOP_REJ_TIMER(linkp);
			LLC_SETFLAG(linkp, DATA, 0);
			action = LLC_DATA_INDICATION;			
		} else if ((cmdrsp == LLC_CMD && pollfinal == 0 && p == 0) ||
			   (cmdrsp == LLC_RSP && pollfinal == p)) {
			LLC_INC(linkp->llcl_vr);
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			if (LLC_GETFLAG(linkp, DATA) == 2)
				LLC_STOP_REJ_TIMER(linkp);
			if (cmdrsp == LLC_RSP && pollfinal == 1)
				LLC_CLEAR_REMOTE_BUSY(linkp, action);
			action = LLC_DATA_INDICATION;
		} else if (pollfinal == 0 && p == 1) {
			LLC_INC(linkp->llcl_vr);
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 0);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			if (LLC_GETFLAG(linkp, DATA) == 2)
				LLC_STOP_REJ_TIMER(linkp);
			LLC_SETFLAG(linkp, DATA, 0);
			action = LLC_DATA_INDICATION;
		}
		break;
	}
	case LLCFT_RR + LLC_CMD:
	case LLCFT_RR + LLC_RSP: 
	case LLCFT_RNR + LLC_CMD:
	case LLCFT_RNR + LLC_RSP: { 
		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);
		
		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			llc_send(linkp, LLCFT_RNR, LLC_RSP, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			if (frame_kind == LLCFT_RR) {
				LLC_CLEAR_REMOTE_BUSY(linkp, action);
			} else {
				LLC_SET_REMOTE_BUSY(linkp, action);
			}
		} else if (pollfinal = 0 || 
			   (cmdrsp == LLC_RSP && pollfinal == 1)) {
			LLC_UPDATE_P_FLAG(linkp, cmdrsp, pollfinal);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			if (frame_kind == LLCFT_RR) {
				LLC_CLEAR_REMOTE_BUSY(linkp, action);
			} else  {
				LLC_SET_REMOTE_BUSY(linkp, action);
			}
		}
		break;
	}
	case LLCFT_REJ + LLC_CMD:
	case LLCFT_REJ + LLC_RSP: {
		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);

		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			linkp->llcl_vs = nr;
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			llc_send(linkp, LLCFT_RNR, LLC_RSP, 1);
			llc_resend(linkp, LLC_CMD, 0);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
		} else if ((cmdrsp == LLC_CMD && pollfinal == 0 && p == 0) ||
			   (cmdrsp == LLC_RSP && pollfinal == p)) {
			linkp->llcl_vs = nr;
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_UPDATE_P_FLAG(linkp, cmdrsp, pollfinal);
			llc_resend(linkp, LLC_CMD, 0);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
		} else if (pollfinal == 0 && p == 1) {
			linkp->llcl_vs = nr;
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			llc_resend(linkp, LLC_CMD, 0);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
		}
		break;
	}
	case NL_INITIATE_PF_CYCLE:
		if (LLC_GETFLAG(linkp, P) == 0) {
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			action = 0;
		}
		break;
	case LLC_P_TIMER_EXPIRED:
		/* multiple possibilities */
		if (linkp->llcl_retry < llc_n2) {
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			linkp->llcl_retry++;
			LLC_NEWSTATE(linkp, AWAIT_BUSY);
			action = 0;
		}
		break;
	case LLC_ACK_TIMER_EXPIRED:
	case LLC_BUSY_TIMER_EXPIRED:
		if (LLC_GETFLAG(linkp, P) == 0 && linkp->llcl_retry < llc_n2) {
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			linkp->llcl_retry++;
			LLC_NEWSTATE(linkp, AWAIT_BUSY);
			action = 0;
		}
		break;
	case LLC_REJ_TIMER_EXPIRED:
		if (linkp->llcl_retry < llc_n2) 
			if (LLC_GETFLAG(linkp, P) == 0) {
				/* multiple possibilities */
				llc_send(linkp, LLCFT_RNR, LLC_CMD, 1);
				LLC_START_P_TIMER(linkp);
				linkp->llcl_retry++;
				LLC_SETFLAG(linkp, DATA, 1);
				LLC_NEWSTATE(linkp, AWAIT_BUSY);
				action = 0;
			} else{
				LLC_SETFLAG(linkp, DATA, 1);
				LLC_NEWSTATE(linkp, BUSY);
				action = 0;
			}
		
		break;
	}
	if (action == LLC_PASSITON)
		action = llc_state_NBRAcore(linkp, frame, frame_kind, 
					    cmdrsp, pollfinal);

	return action;
}

/*
 * REJECT --- A data link connection exists between the local LLC service
 *            access point and the remote LLC service access point. The local
 *            connection component has requested that the remote connection
 *            component resend a specific I PDU that the local connection
 *            componnent has detected as being out of sequence. Both I PDUs and
 *            supervisory PDUs may be sent and received.
 */ 
int
llc_state_REJECT(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, P) == 0) {
			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);
			LLC_NEWSTATE(linkp, REJECT);
			action = 0;
		} else { 
			llc_send(linkp, LLCFT_INFO, LLC_CMD, 0);
			if (LLC_TIMERXPIRED(linkp, ACK) != LLC_TIMER_RUNNING)
				LLC_START_ACK_TIMER(linkp);
			LLC_NEWSTATE(linkp, REJECT);
			action = 0;
		}
		break;
	case NL_LOCAL_BUSY_DETECTED:
		if (LLC_GETFLAG(linkp, P) == 0) {
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			LLC_SETFLAG(linkp, DATA, 2);
			LLC_NEWSTATE(linkp, BUSY);
			action = 0;
		} else {
			llc_send(linkp, LLCFT_RNR, LLC_CMD, 0);
			LLC_SETFLAG(linkp, DATA, 2);
			LLC_NEWSTATE(linkp, BUSY);
			action = 0;
		}
		break;
	case LLC_INVALID_NS + LLC_CMD:
	case LLC_INVALID_NS + LLC_RSP: { 
		register int p = LLC_GETFLAG(linkp, P);
		register int nr = LLCGBITS(frame->llc_control_ext, s_nr);

		if (cmdrsp == LLC_CMD && pollfinal == 1) {
			llc_send(linkp, LLCFT_RR, LLC_RSP, 1);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);