llc_subr.c

早期freebsd实现

 * AWAIT_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 re-transmit a specific I PDU that the
 *                  local connection component has detected as being out of
 *                  sequence. Before the local LLC entered this state it was
 *                  performing a timer recovery operation and had sent a
 *                  command PDU with the P bit set to ``1'', and is still
 *                  awaiting an acknowledgment from the remote LLC. I PDUs may
 *                  be received but not transmitted. Supervisory PDUs may be
 *                  both transmitted and received.
 */
int
llc_state_AWAIT_REJECT(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		       int cmdrsp, int pollfinal)
{
	int action = LLC_PASSITON;

	switch(frame_kind + cmdrsp) {
	case LLC_LOCAL_BUSY_DETECTED:
		llc_send(linkp, LLCFT_RNR, LLC_CMD, 0);
		LLC_SETFLAG(linkp, DATA, 2);
		LLC_NEWSTATE(linkp, AWAIT_BUSY);
		action = 0;
		break;
	case LLC_INVALID_NS + LLC_CMD:
	case LLC_INVALID_NS + LLC_RSP: {
		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);
			action = 0;
		} else if (cmdrsp == LLC_RSP && pollfinal == 1) {
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			linkp->llcl_vs = nr;
			llc_resend(linkp, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
			LLC_NEWSTATE(linkp, REJECT);
		} else if (pollfinal == 0) {
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			action = 0;	
		}
		break;
	}
	case LLCFT_INFO + LLC_CMD:
	case LLCFT_INFO + LLC_RSP: {
		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_RR, LLC_RSP, 1);
			LLC_STOP_REJ_TIMER(linkp);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_NEWSTATE(linkp, AWAIT);
			action = LLC_DATA_INDICATION;
		} else if (cmdrsp == LLC_RSP && pollfinal == 1) {
			LLC_INC(linkp->llcl_vr);
			LLC_STOP_P_TIMER(linkp);
			LLC_STOP_REJ_TIMER(linkp);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			linkp->llcl_vs = nr;
			llc_resend(linkp, LLC_CMD, 0);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
			LLC_NEWSTATE(linkp, NORMAL);
			action = LLC_DATA_INDICATION;
		} else if (pollfinal == 0) {
			LLC_INC(linkp->llcl_vr);
			llc_send(linkp, LLCFT_RR, LLC_CMD, 0);
			LLC_STOP_REJ_TIMER(linkp);
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_NEWSTATE(linkp, AWAIT);
			action = LLC_DATA_INDICATION;
		}
		break;
	}
	case LLCFT_RR + LLC_CMD:
	case LLCFT_REJ + LLC_CMD:
	case LLCFT_RR + LLC_RSP:
	case LLCFT_REJ + LLC_RSP: {
		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_CLEAR_REMOTE_BUSY(linkp, action);
		} else if (cmdrsp == LLC_RSP && pollfinal == 1) {
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			linkp->llcl_vs = nr;
			llc_resend(linkp, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			LLC_CLEAR_REMOTE_BUSY(linkp, action);
			LLC_NEWSTATE(linkp, REJECT);
		} else if (pollfinal == 0) {
			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 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 (cmdrsp == LLC_RSP && pollfinal == 1) {
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			linkp->llcl_vs = nr;
			LLC_STOP_P_TIMER(linkp);
			LLC_SET_REMOTE_BUSY(linkp, action);
			LLC_NEWSTATE(linkp, REJECT);
		} else if (pollfinal == 0) {
			LLC_UPDATE_NR_RECEIVED(linkp, nr);
			LLC_SET_REMOTE_BUSY(linkp, action);
		}
		break;
	}
	case LLC_P_TIMER_EXPIRED:
		if (linkp->llcl_retry < llc_n2) {
			llc_send(linkp, LLCFT_REJ, LLC_CMD, 1);
			LLC_START_P_TIMER(linkp);
			linkp->llcl_retry++;
			action = 0;
		}
		break;
	}
	if (action == LLC_PASSITON)
		action = llc_state_NBRAcore(linkp, frame, frame_kind, 
					    cmdrsp, pollfinal);

	return action;
}


/*
 * llc_statehandler() --- Wrapper for llc_state_*() functions.
 *                         Deals with action codes and checks for
 *                         ``stuck'' links.
 */

int
llc_statehandler(struct llc_linkcb *linkp, struct llc *frame, int frame_kind,
		 int cmdrsp, int pollfinal)
{
	register int action = 0;

	/*
	 * To check for ``zombie'' links each time llc_statehandler() gets called
	 * the AGE timer of linkp is reset. If it expires llc_timer() will
	 * take care of the link --- i.e. kill it 8=)
	 */
	LLC_STARTTIMER(linkp, AGE);

	/*
	 * Now call the current statehandler function.
	 */
	action = (*linkp->llcl_statehandler)(linkp, frame, frame_kind, 
					     cmdrsp, pollfinal);
once_more_and_again:
	switch (action) {
	case LLC_CONNECT_INDICATION: {
		int naction;

		LLC_TRACE(linkp, LLCTR_INTERESTING, "CONNECT INDICATION");
		linkp->llcl_nlnext = 
		     (*linkp->llcl_sapinfo->si_ctlinput)
		      (PRC_CONNECT_INDICATION,
		       (struct sockaddr *) &linkp->llcl_addr, (caddr_t) linkp);
		if (linkp->llcl_nlnext == 0)
			naction = NL_DISCONNECT_REQUEST;
		else naction = NL_CONNECT_RESPONSE;
		action = (*linkp->llcl_statehandler)(linkp, frame, naction, 0, 0);
		goto once_more_and_again;
	}
	case LLC_CONNECT_CONFIRM:
		/* llc_resend(linkp, LLC_CMD, 0); */
		llc_start(linkp);
		break;
	case LLC_DISCONNECT_INDICATION:
		LLC_TRACE(linkp, LLCTR_INTERESTING, "DISCONNECT INDICATION");
		(*linkp->llcl_sapinfo->si_ctlinput)
		  (PRC_DISCONNECT_INDICATION, 
		   (struct sockaddr *) &linkp->llcl_addr, linkp->llcl_nlnext);
		break;
        /* internally visible only */
	case LLC_RESET_CONFIRM:
	case LLC_RESET_INDICATION_LOCAL:
		/*
		 * not much we can do here, the state machine either makes it or
		 * brakes it ...
		 */
		break;
	case LLC_RESET_INDICATION_REMOTE:
		LLC_TRACE(linkp, LLCTR_SHOULDKNOW, "RESET INDICATION (REMOTE)");
		action = (*linkp->llcl_statehandler)(linkp, frame, 
						     NL_RESET_RESPONSE, 0, 0);
		goto once_more_and_again;
	case LLC_FRMR_SENT:
		LLC_TRACE(linkp, LLCTR_URGENT, "FRMR SENT");
		break;
	case LLC_FRMR_RECEIVED:
		LLC_TRACE(linkp, LLCTR_URGEN, "FRMR RECEIVED");
		action = (*linkp->llcl_statehandler)(linkp, frame,
						     NL_RESET_REQUEST, 0, 0);
		
		goto once_more_and_again;
	case LLC_REMOTE_BUSY:
		LLC_TRACE(linkp, LLCTR_SHOULDKNOW, "REMOTE BUSY");
		break;
	case LLC_REMOTE_NOT_BUSY:
		LLC_TRACE(linkp, LLCTR_SHOULDKNOW, "REMOTE BUSY CLEARED");
		/*
		 * try to get queued frames out
		 */
		llc_start(linkp);
		break;
	}		

	/*
         * Only LLC_DATA_INDICATION is for the time being
	 * passed up to the network layer entity.
	 * The remaining action codes are for the time 
	 * being visible internally only.
         * However, this can/may be changed if necessary.
	 */

	return action;
}


/*
 * Core LLC2 routines
 */ 

/*
 * The INIT call. This routine is called once after the system is booted.
 */

llc_init()
{
	llcintrq.ifq_maxlen = IFQ_MAXLEN;
}


/*
 * In case of a link reset we need to shuffle the frames queued inside the
 * LLC2 window.
 */

void
llc_resetwindow(struct llc_linkcb *linkp)
{
	register struct mbuf *mptr = (struct mbuf *) 0;
	register struct mbuf *anchor = (struct mbuf *)0;
	register short i;

	/* Pick up all queued frames and collect them in a linked mbuf list */
	if (linkp->llcl_slotsfree != linkp->llcl_window) {
		i = llc_seq2slot(linkp, linkp->llcl_nr_received);
		anchor = mptr = linkp->llcl_output_buffers[i]; 
		for (; i != linkp->llcl_freeslot; 
		     i = llc_seq2slot(linkp, i+1)) {
			if (linkp->llcl_output_buffers[i]) {
				mptr->m_nextpkt = linkp->llcl_output_buffers[i];
				mptr = mptr->m_nextpkt;
			} else panic("LLC2 window broken");
		}
	}
	/* clean closure */
	if (mptr)
		mptr->m_nextpkt = (struct mbuf *) 0;

	/* Now --- plug 'em in again */
	if (anchor != (struct mbuf *)0) {
		for (i = 0, mptr = anchor; mptr != (struct mbuf *) 0; i++) {
			linkp->llcl_output_buffers[i] = mptr;
			mptr = mptr->m_nextpkt;
			linkp->llcl_output_buffers[i]->m_nextpkt = (struct mbuf *)0;
		}
		linkp->llcl_freeslot = i;
	} else linkp->llcl_freeslot = 0;
	
	/* We're resetting the link, the next frame to be acknowledged is 0 */
	linkp->llcl_nr_received = 0;

	/* set distance between LLC2 sequence number and the top of window to 0 */
	linkp->llcl_projvs = linkp->llcl_freeslot;

	return;
}
			
/*
 * llc_newlink() --- We allocate enough memory to contain a link control block
 *                   and initialize it properly. We don't intiate the actual setup
 *                   of the LLC2 link here.
 */
struct llc_linkcb *
llc_newlink(struct sockaddr_dl *dst, struct ifnet *ifp, struct rtentry *nlrt, 
	    caddr_t nlnext, struct rtentry *llrt)
{
	struct llc_linkcb *nlinkp;
	u_char sap = LLSAPADDR(dst);
	short llcwindow;


	/* allocate memory for link control block */
	MALLOC(nlinkp, struct llc_linkcb *, sizeof(struct llc_linkcb),
	       M_PCB, M_DONTWAIT);
	if (nlinkp == 0)
		return (NULL);
	bzero((caddr_t)nlinkp, sizeof(struct llc_linkcb));
	
	/* copy link address */
	sdl_copy(dst, &nlinkp->llcl_addr);

	/* hold on to the network layer route entry */
	nlinkp->llcl_nlrt = nlrt;

	/* likewise the network layer control block */
	nlinkp->llcl_nlnext = nlnext;

	/* jot down the link layer route entry */
	nlinkp->llcl_llrt = llrt;

	/* reset writeq */
	nlinkp->llcl_writeqh = nlinkp->llcl_writeqt = NULL;

	/* setup initial state handler function */
	nlinkp->llcl_statehandler = llc_state_ADM;
	
	/* hold on to interface pointer */
	nlinkp->llcl_if = ifp;

	/* get service access point information */
	nlinkp->llcl_sapinfo = llc_getsapinfo(sap, ifp);

	/* get window size from SAP info block */
	if ((llcwindow = nlinkp->llcl_sapinfo->si_window) == 0)
		llcwindow = LLC_MAX_WINDOW;

	/* allocate memory for window buffer */
	MALLOC(nlinkp->llcl_output_buffers, struct mbuf **, 
	       llcwindow*sizeof(struct mbuf *), M_PCB, M_DONTWAIT);
	if (nlinkp->llcl_output_buffers == 0) {
		FREE(nlinkp, M_PCB);
		return(NULL);
	}
	bzero((caddr_t)nlinkp->llcl_output_buffers, 
	      llcwindow*sizeof(struct mbuf *));

	/* set window size & slotsfree */
	nlinkp->llcl_slotsfree = nlinkp->llcl_window = llcwindow;

	/* enter into linked listed of link control blocks */
	insque(nlinkp, &llccb_q);

	return(nlinkp);
}

/*
 * llc_dellink() --- farewell to link control block
 */
llc_dellink(struct llc_linkcb *linkp)
{
	register struct mbuf *m;
	register struct mbuf *n;
	register struct npaidbentry *sapinfo = linkp->llcl_sapinfo;
	register i;

	/* notify upper layer of imminent death */
	if (linkp->llcl_nlnext && sapinfo->si_ctlinput)
		(*sapinfo->si_ctlinput)
		   (PRC_DISCONNECT_INDICATION, 
		    (struct sockaddr *)&linkp->llcl_addr, linkp->llcl_nlnext);

	/* pull the plug */
	if (linkp->llcl_llrt)
		((struct npaidbentry *)(linkp->llcl_llrt->rt_llinfo))->np_link 
			= (struct llc_linkcb *) 0;

	/* leave link control block queue */
	remque(linkp);

	/* drop queued packets */
	for (m = linkp->llcl_writeqh; m;) {
		n = m->m_act;
		m_freem(m);
		m = n;
	}

	/* drop packets in the window */
	for(i = 0; i < linkp->llcl_window; i++)
		if (linkp->llcl_output_buffers[i])
			m_freem(linkp->llcl_output_buffers[i]);

	/* return the window space */
	FREE((caddr_t)linkp->llcl_output_buffers, M_PCB);

	/* return the control block space --- now it's gone ... */
	FREE((caddr_t)linkp, M_PCB);
}

llc_decode(struct llc* frame, struct llc_linkcb * linkp)
{
	register int ft = LLC_BAD_PDU;

	if ((frame->llc_control & 01) == 0) {
		ft = LLCFT_INFO;
	/* S or U frame ? */
	} else switch (frame->llc_control) {

	/* U frames */
	case LLC_UI:
	case LLC_UI_P:     ft = LLC_UI; break;
	case LLC_DM:
	case LLC_DM_P:     ft =LLCFT_DM; break;
	case LLC_DISC:
	case LLC_DISC_P:   ft = LLCFT_DISC; break;
	case LLC_UA:
	case LLC_UA_P:     ft = LLCFT_UA; break;
	case LLC_SABME:
	case LLC_SABME_P:  ft = LLCFT_SABME; break;
	case LLC_FRMR:
	case LLC_FRMR_P:   ft = LLCFT_FRMR; break;
	case LLC_XID:
	case LLC_XID_P:    ft = LLCFT_XID; break;
	case LLC_TEST:
	case LLC_TEST_P:   ft = LLCFT_TEST; break;

	/* S frames */
	case LLC_RR:       ft = LLCFT_RR; break;
	case LLC_RNR:      ft = LLCFT_RNR; break;
	case LLC_REJ:      ft = LLCFT_REJ; break;
	} /* switch */

	if (linkp) {
		switch (ft) {
		case LLCFT_INFO:
			if (LLCGBITS(frame->llc_control, i_ns) != linkp->llcl_vr) {
				ft = LLC_INVALID_NS;
				break;
			}
			/* fall thru --- yeeeeeee */
		case LLCF