text: 
  /*
   * ng_lmi.c
   *
   * Copyright (c) 1996-1999 Whistle Communications, Inc.
   * All rights reserved.
   * 
   * Subject to the following obligations and disclaimer of warranty, use and
   * redistribution of this software, in source or object code forms, with or
   * without modifications are expressly permitted by Whistle Communications;
   * provided, however, that:
   * 1. Any and all reproductions of the source or object code must include the
   *    copyright notice above and the following disclaimer of warranties; and
   * 2. No rights are granted, in any manner or form, to use Whistle
   *    Communications, Inc. trademarks, including the mark "WHISTLE
   *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
   *    such appears in the above copyright notice or in the software.
   * 
   * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
   * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
   * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
   * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
   * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
   * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
   * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
   * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
   * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
   * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
   * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
   * OF SUCH DAMAGE.
   *
   * Author: Julian Elischer <julian@whistle.com>
   *
   * $FreeBSD: src/sys/netgraph/ng_lmi.c,v 1.3.2.3 1999/12/01 19:41:45 julian Exp $
   * $Whistle: ng_lmi.c,v 1.38 1999/11/01 09:24:52 julian Exp $
   */
  
  /*
   * This node performs the frame relay LMI protocol. It knows how
   * to do ITU Annex A, ANSI Annex D, and "Group-of-Four" variants
   * of the protocol.
   *
   * A specific protocol can be forced by connecting the corresponding
   * hook to DLCI 0 or 1023 (as appropriate) of a frame relay link.
   *
   * Alternately, this node can do auto-detection of the LMI protocol
   * by connecting hook "auto0" to DLCI 0 and "auto1023" to DLCI 1023.
   */
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/errno.h>
  #include <sys/kernel.h>
  #include <sys/malloc.h>
  #include <sys/mbuf.h>
  #include <sys/syslog.h>
  #include <netgraph/ng_message.h>
  #include <netgraph/netgraph.h>
  #include <netgraph/ng_lmi.h>
  
  /*
   * Human readable names for LMI
   */
  #define NAME_ANNEXA	NG_LMI_HOOK_ANNEXA
  #define NAME_ANNEXD	NG_LMI_HOOK_ANNEXD
  #define NAME_GROUP4	NG_LMI_HOOK_GROUPOF4
  #define NAME_NONE	"None"
  
  #define MAX_DLCIS	128
  #define MAXDLCI		1023
  
  /*
   * DLCI states
   */
  #define DLCI_NULL	0
  #define DLCI_UP		1
  #define DLCI_DOWN	2
  
  /*
   * Any received LMI frame should be at least this long
   */
  #define LMI_MIN_LENGTH	8	/* XXX verify */
  
  /*
   * Netgraph node methods and type descriptor
   */
  static ng_constructor_t	nglmi_constructor;
  static ng_rcvmsg_t	nglmi_rcvmsg;
  static ng_shutdown_t	nglmi_rmnode;
  static ng_newhook_t	nglmi_newhook;
  static ng_rcvdata_t	nglmi_rcvdata;
  static ng_disconnect_t	nglmi_disconnect;
  static int	nglmi_checkdata(hook_p hook, struct mbuf *m, meta_p meta);
  
  static struct ng_type typestruct = {
  	NG_VERSION,
  	NG_LMI_NODE_TYPE,
  	NULL,
  	nglmi_constructor,
  	nglmi_rcvmsg,
  	nglmi_rmnode,
  	nglmi_newhook,
  	NULL,
  	NULL,
  	nglmi_rcvdata,
  	nglmi_rcvdata,
  	nglmi_disconnect,
  	NULL
  };
  NETGRAPH_INIT(lmi, &typestruct);
  
  /*
   * Info and status per node
   */
  struct nglmi_softc {
  	node_p  node;		/* netgraph node */
  	int     flags;		/* state */
  	int     poll_count;	/* the count of times for autolmi */
  	int     poll_state;	/* state of auto detect machine */
  	u_char  remote_seq;	/* sequence number the remote sent */
  	u_char  local_seq;	/* last sequence number we sent */
  	u_char  protoID;	/* 9 for group of 4, 8 otherwise */
  	u_long  seq_retries;	/* sent this how many time so far */
  	struct callout_handle handle;	/* see timeout(9) */
  	int     liv_per_full;
  	int     liv_rate;
  	int     livs;
  	int     need_full;
  	hook_p  lmi_channel;	/* whatever we ended up using */
  	hook_p  lmi_annexA;
  	hook_p  lmi_annexD;
  	hook_p  lmi_group4;
  	hook_p  lmi_channel0;	/* auto-detect on DLCI 0 */
  	hook_p  lmi_channel1023;/* auto-detect on DLCI 1023 */
  	char   *protoname;	/* cache protocol name */
  	u_char  dlci_state[MAXDLCI + 1];
  	int     invalidx;	/* next dlci's to invalidate */
  };
  typedef struct nglmi_softc *sc_p;
  
  /*
   * Other internal functions
   */
  static void	LMI_ticker(void *arg);
  static void	nglmi_startup_fixed(sc_p sc, hook_p hook);
  static void	nglmi_startup_auto(sc_p sc);
  static void	nglmi_startup(sc_p sc);
  static void	nglmi_inquire(sc_p sc, int full);
  static void	ngauto_state_machine(sc_p sc);
  
  /*
   * Values for 'flags' field
   * NB: the SCF_CONNECTED flag is set if and only if the timer is running.
   */
  #define	SCF_CONNECTED	0x01	/* connected to something */
  #define	SCF_AUTO	0x02	/* we are auto-detecting */
  #define	SCF_FIXED	0x04	/* we are fixed from the start */
  
  #define	SCF_LMITYPE	0x18	/* mask for determining Annex mode */
  #define	SCF_NOLMI	0x00	/* no LMI type selected yet */
  #define	SCF_ANNEX_A	0x08	/* running annex A mode */
  #define	SCF_ANNEX_D	0x10	/* running annex D mode */
  #define	SCF_GROUP4	0x18	/* running group of 4 */
  
  #define SETLMITYPE(sc, annex)						\
  do {									\
  	(sc)->flags &= ~SCF_LMITYPE;					\
  	(sc)->flags |= (annex);						\
  } while (0)
  
  #define NOPROTO(sc) (((sc)->flags & SCF_LMITYPE) == SCF_NOLMI)
  #define ANNEXA(sc) (((sc)->flags & SCF_LMITYPE) == SCF_ANNEX_A)
  #define ANNEXD(sc) (((sc)->flags & SCF_LMITYPE) == SCF_ANNEX_D)
  #define GROUP4(sc) (((sc)->flags & SCF_LMITYPE) == SCF_GROUP4)
  
  #define LMIPOLLSIZE	3
  #define LMI_PATIENCE	8	/* declare all DLCI DOWN after N LMI failures */
  
  /*
   * Node constructor
   */
  static int
  nglmi_constructor(node_p *nodep)
  {
  	sc_p sc;
  	int error = 0;
  
  	MALLOC(sc, sc_p, sizeof(*sc), M_NETGRAPH, M_WAITOK);
  	if (sc == NULL)
  		return (ENOMEM);
  	bzero(sc, sizeof(*sc));
  
  	callout_handle_init(&sc->handle);
  	if ((error = ng_make_node_common(&typestruct, nodep))) {
  		FREE(sc, M_NETGRAPH);
  		return (error);
  	}
  	(*nodep)->private = sc;
  	sc->protoname = NAME_NONE;
  	sc->node = *nodep;
  	sc->liv_per_full = NG_LMI_SEQ_PER_FULL;	/* make this dynamic */
  	sc->liv_rate = NG_LMI_KEEPALIVE_RATE;
  	return (0);
  }
  
  /*
   * The LMI channel has a private pointer which is the same as the
   * node private pointer. The debug channel has a NULL private pointer.
   */
  static int
  nglmi_newhook(node_p node, hook_p hook, const char *name)
  {
  	sc_p sc = node->private;
  
  	if (strcmp(name, NG_LMI_HOOK_DEBUG) == 0) {
  		hook->private = NULL;
  		return (0);
  	}
  	if (sc->flags & SCF_CONNECTED) {
  		/* already connected, return an error */
  		return (EINVAL);
  	}
  	if (strcmp(name, NG_LMI_HOOK_ANNEXA) == 0) {
  		sc->lmi_annexA = hook;
  		hook->private = node->private;
  		sc->protoID = 8;
  		SETLMITYPE(sc, SCF_ANNEX_A);
  		sc->protoname = NAME_ANNEXA;
  		nglmi_startup_fixed(sc, hook);
  	} else if (strcmp(name, NG_LMI_HOOK_ANNEXD) == 0) {
  		sc->lmi_annexD = hook;
  		hook->private = node->private;
  		sc->protoID = 8;
  		SETLMITYPE(sc, SCF_ANNEX_D);
  		sc->protoname = NAME_ANNEXD;
  		nglmi_startup_fixed(sc, hook);
  	} else if (strcmp(name, NG_LMI_HOOK_GROUPOF4) == 0) {
  		sc->lmi_group4 = hook;
  		hook->private = node->private;
  		sc->protoID = 9;
  		SETLMITYPE(sc, SCF_GROUP4);
  		sc->protoname = NAME_GROUP4;
  		nglmi_startup_fixed(sc, hook);
  	} else if (strcmp(name, NG_LMI_HOOK_AUTO0) == 0) {
  		/* Note this, and if B is already installed, we're complete */
  		sc->lmi_channel0 = hook;
  		sc->protoname = NAME_NONE;
  		hook->private = node->private;
  		if (sc->lmi_channel1023)
  			nglmi_startup_auto(sc);
  	} else if (strcmp(name, NG_LMI_HOOK_AUTO1023) == 0) {
  		/* Note this, and if A is already installed, we're complete */
  		sc->lmi_channel1023 = hook;
  		sc->protoname = NAME_NONE;
  		hook->private = node->private;
  		if (sc->lmi_channel0)
  			nglmi_startup_auto(sc);
  	} else
  		return (EINVAL);		/* unknown hook */
  	return (0);
  }
  
  /*
   * We have just attached to a live (we hope) node.
   * Fire out a LMI inquiry, and then start up the timers.
   */
  static void
  LMI_ticker(void *arg)
  {
  	sc_p sc = arg;
  	int s = splnet();
  
  	if (sc->flags & SCF_AUTO) {
  		ngauto_state_machine(sc);
  		sc->handle = timeout(LMI_ticker, sc, NG_LMI_POLL_RATE * hz);
  	} else {
  		if (sc->livs++ >= sc->liv_per_full) {
  			nglmi_inquire(sc, 1);
  			/* sc->livs = 0; *//* do this when we get the answer! */
  		} else {
  			nglmi_inquire(sc, 0);
  		}
  		sc->handle = timeout(LMI_ticker, sc, sc->liv_rate * hz);
  	}
  	splx(s);
  }
  
  static void
  nglmi_startup_fixed(sc_p sc, hook_p hook)
  {
  	sc->flags |= (SCF_FIXED | SCF_CONNECTED);
  	sc->lmi_channel = hook;
  	nglmi_startup(sc);
  }
  
  static void
  nglmi_startup_auto(sc_p sc)
  {
  	sc->flags |= (SCF_AUTO | SCF_CONNECTED);
  	sc->poll_state = 0;	/* reset state machine */
  	sc->poll_count = 0;
  	nglmi_startup(sc);
  }
  
  static void
  nglmi_startup(sc_p sc)
  {
  	sc->remote_seq = 0;
  	sc->local_seq = 1;
  	sc->seq_retries = 0;
  	sc->livs = sc->liv_per_full - 1;
  	/* start off the ticker in 1 sec */
  	sc->handle = timeout(LMI_ticker, sc, hz);
  }
  
  #define META_PAD 16
  static void
  nglmi_inquire(sc_p sc, int full)
  {
  	struct mbuf *m;
  	char   *cptr, *start;
  	int     error;
  	meta_p  meta = NULL;
  
  	if (sc->lmi_channel == NULL)
  		return;
  	MGETHDR(m, M_DONTWAIT, MT_DATA);
  	if (m == NULL) {
  		log(LOG_ERR, "nglmi: unable to start up LMI processing\n");
  		return;
  	}
  	m->m_pkthdr.rcvif = NULL;
  	/* Allocate a meta struct (and leave some slop for options to be
  	 * added by other modules). */
  	/* MALLOC(meta, meta_p, sizeof( struct ng_meta) + META_PAD,
  	 * M_NETGRAPH, M_NOWAIT); */
  	MALLOC(meta, meta_p, sizeof(*meta) + META_PAD, M_NETGRAPH, M_NOWAIT);
  	if (meta != NULL) {	/* if it failed, well, it was optional anyhow */
  		meta->used_len = (u_short) sizeof(struct ng_meta);
  		meta->allocated_len
  		    = (u_short) sizeof(struct ng_meta) + META_PAD;
  		meta->flags = 0;
  		meta->priority = NG_LMI_LMI_PRIORITY;
  		meta->discardability = -1;
  	}
  	m->m_data += 4;		/* leave some room for a header */
  	cptr = start = mtod(m, char *);
  	/* add in the header for an LMI inquiry. */
  	*cptr++ = 0x03;		/* UI frame */
  	if (GROUP4(sc))
  		*cptr++ = 0x09;	/* proto discriminator */
  	else
  		*cptr++ = 0x08;	/* proto discriminator */
  	*cptr++ = 0x00;		/* call reference */
  	*cptr++ = 0x75;		/* inquiry */
  
  	/* If we are Annex-D, there is this extra thing.. */
  	if (ANNEXD(sc))
  		*cptr++ = 0x95;	/* ??? */
  	/* Add a request type */
  	if (ANNEXA(sc))
  		*cptr++ = 0x51;	/* report type */
  	else
  		*cptr++ = 0x01;	/* report type */
  	*cptr++ = 0x01;		/* size = 1 */
  	if (full)
  		*cptr++ = 0x00;	/* full */
  	else
  		*cptr++ = 0x01;	/* partial */
  
  	/* Add a link verification IE */
  	if (ANNEXA(sc))
  		*cptr++ = 0x53;	/* verification IE */
  	else
  		*cptr++ = 0x03;	/* verification IE */
  	*cptr++ = 0x02;		/* 2 extra bytes */
  	*cptr++ = sc->local_seq;
  	*cptr++ = sc->remote_seq;
  	sc->seq_retries++;
  
  	/* Send it */
  	m->m_len = m->m_pkthdr.len = cptr - start;
  	NG_SEND_DATA(error, sc->lmi_channel, m, meta);
  
  	/* If we've been sending requests for long enough, and there has
  	 * been no response, then mark as DOWN, any DLCIs that are UP. */
  	if (sc->seq_retries == LMI_PATIENCE) {
  		int     count;
  
  		for (count = 0; count < MAXDLCI; count++)
  			if (sc->dlci_state[count] == DLCI_UP)
  				sc->dlci_state[count] = DLCI_DOWN;
  	}
  }
  
  /*
   * State machine for LMI auto-detect. The transitions are ordered
   * to try the more likely possibilities first.
   */
  static void
  ngauto_state_machine(sc_p sc)
  {
  	if ((sc->poll_count <= 0) || (sc->poll_count > LMIPOLLSIZE)) {
  		/* time to change states in the auto probe machine */
  		/* capture wild values of poll_count while we are at it */
  		sc->poll_count = LMIPOLLSIZE;
  		sc->poll_state++;
  	}
  	switch (sc->poll_state) {
  	case 7:
  		log(LOG_WARNING, "nglmi: no response from exchange\n");
  	default:		/* capture bad states */
  		sc->poll_state = 1;
  	case 1:
  		sc->lmi_channel = sc->lmi_channel0;
  		SETLMITYPE(sc, SCF_ANNEX_D);
  		break;
  	case 2:
  		sc->lmi_channel = sc->lmi_channel1023;
  		SETLMITYPE(sc, SCF_ANNEX_D);
  		break;
  	case 3:
  		sc->lmi_channel = sc->lmi_channel0;
  		SETLMITYPE(sc, SCF_ANNEX_A);
  		break;
  	case 4:
  		sc->lmi_channel = sc->lmi_channel1023;
  		SETLMITYPE(sc, SCF_GROUP4);
  		break;
  	case 5:
  		sc->lmi_channel = sc->lmi_channel1023;
  		SETLMITYPE(sc, SCF_ANNEX_A);
  		break;
  	case 6:
  		sc->lmi_channel = sc->lmi_channel0;
  		SETLMITYPE(sc, SCF_GROUP4);
  		break;
  	}
  
  	/* send an inquirey encoded appropriatly */
  	nglmi_inquire(sc, 0);
  	sc->poll_count--;
  }
  
  /*
   * Receive a netgraph control message.
   */
  static int
  nglmi_rcvmsg(node_p node, struct ng_mesg *msg, const char *retaddr,
  	     struct ng_mesg **resp)
  {
  	int     error = 0;
  	sc_p    sc = node->private;
  
  	switch (msg->header.typecookie) {
  	case NGM_GENERIC_COOKIE:
  		switch (msg->header.cmd) {
  		case NGM_TEXT_STATUS:
  		    {
  			char   *arg;
  			int     pos, count;
  
  			NG_MKRESPONSE(*resp, msg, NG_TEXTRESPONSE, M_NOWAIT);
  			if (*resp == NULL) {
  				error = ENOMEM;
  				break;
  			}
  			arg = (*resp)->data;
  			pos = sprintf(arg, "protocol %s ", sc->protoname);
  			if (sc->flags & SCF_FIXED)
  				pos += sprintf(arg + pos, "fixed\n");
  			else if (sc->flags & SCF_AUTO)
  				pos += sprintf(arg + pos, "auto-detecting\n");
  			else
  				pos += sprintf(arg + pos, "auto on dlci %d\n",
  				    (sc->lmi_channel == sc->lmi_channel0) ?
  				    0 : 1023);
  			pos += sprintf(arg + pos,
  			    "keepalive period: %d seconds\n", sc->liv_rate);
  			pos += sprintf(arg + pos,
  			    "unacknowledged keepalives: %ld\n",
  			    sc->seq_retries);
  			for (count = 0;
  			     ((count <= MAXDLCI)
  			      && (pos < (NG_TEXTRESPONSE - 20)));
  			     count++) {
  				if (sc->dlci_state[count]) {
  					pos += sprintf(arg + pos,
  					       "dlci %d %s\n", count,
  					       (sc->dlci_state[count]
  					== DLCI_UP) ? "up" : "down");
  				}
  			}
  			(*resp)->header.arglen = pos + 1;
  			break;
  		    }
  		default:
  			error = EINVAL;
  			break;
  		}
  		break;
  	case NGM_LMI_COOKIE:
  		switch (msg->header.cmd) {
  		case NGM_LMI_GET_STATUS:
  		    {
  			struct nglmistat *stat;
  			int k;
  
  			NG_MKRESPONSE(*resp, msg, sizeof(*stat), M_NOWAIT);
  			if (!*resp) {
  				error = ENOMEM;
  				break;
  			}
  			stat = (struct nglmistat *) (*resp)->data;
  			strncpy(stat->proto,
  			     sc->protoname, sizeof(stat->proto) - 1);
  			strncpy(stat->hook,
  			      sc->protoname, sizeof(stat->hook) - 1);
  			stat->autod = !!(sc->flags & SCF_AUTO);
  			stat->fixed = !!(sc->flags & SCF_FIXED);
  			for (k = 0; k <= MAXDLCI; k++) {
  				switch (sc->dlci_state[k]) {
  				case DLCI_UP:
  					stat->up[k / 8] |= (1 << (k % 8));
  					/* fall through */
  				case DLCI_DOWN:
  					stat->seen[k / 8] |= (1 << (k % 8));
  					break;
  				}
  			}
  			break;
  		    }
  		default:
  			error = EINVAL;
  			break;
  		}
  		break;
  	default:
  		error = EINVAL;
  		break;
  	}
  	FREE(msg, M_NETGRAPH);
  	return (error);
  }
  
  #define STEPBY(stepsize)			\
  	do {					\
  		packetlen -= (stepsize);	\
  		data += (stepsize);		\
  	} while (0)
  
  /*
   * receive data, and use it to update our status.
   * Anything coming in on the debug port is discarded.
   */
  static int
  nglmi_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
  {
  	sc_p    sc = hook->node->private;
  	u_char *data;
  	unsigned short dlci;
  	u_short packetlen;
  	int     resptype_seen = 0;
  	int     seq_seen = 0;
  
  	if (hook->private == NULL) {
  		goto drop;
  	}
  	packetlen = m->m_hdr.mh_len;
  
  	/* XXX what if it's more than 1 mbuf? */
  	if ((packetlen > MHLEN) && !(m->m_flags & M_EXT)) {
  		log(LOG_WARNING, "nglmi: packetlen (%d) too big\n", packetlen);
  		goto drop;
  	}
  	if (m->m_len < packetlen && (m = m_pullup(m, packetlen)) == NULL) {
  		log(LOG_WARNING,
  		    "nglmi: m_pullup failed for %d bytes\n", packetlen);
  		NG_FREE_META(meta);
  		return (0);
  	}
  	if (nglmi_checkdata(hook, m, meta) == 0)
  		return (0);
  
  	/* pass the first 4 bytes (already checked in the nglmi_checkdata()) */
  	data = mtod(m, u_char *);
  	STEPBY(4);
  
  	/* Now check if there is a 'locking shift'. This is only seen in
  	 * Annex D frames. don't bother checking, we already did that. Don't
  	 * increment immediatly as it might not be there. */
  	if (ANNEXD(sc))
  		STEPBY(1);
  
  	/* If we get this far we should consider that it is a legitimate
  	 * frame and we know what it is. */
  	if (sc->flags & SCF_AUTO) {
  		/* note the hook that this valid channel came from and drop
  		 * out of auto probe mode. */
  		if (ANNEXA(sc))
  			sc->protoname = NAME_ANNEXA;
  		else if (ANNEXD(sc))
  			sc->protoname = NAME_ANNEXD;
  		else if (GROUP4(sc))
  			sc->protoname = NAME_GROUP4;
  		else {
  			log(LOG_ERR, "nglmi: No known type\n");
  			goto drop;
  		}
  		sc->lmi_channel = hook;
  		sc->flags &= ~SCF_AUTO;
  		log(LOG_INFO, "nglmi: auto-detected %s LMI on DLCI %d\n",
  		    sc->protoname, hook == sc->lmi_channel0 ? 0 : 1023);
  	}
  
  	/* While there is more data in the status packet, keep processing
  	 * status items. First make sure there is enough data for the
  	 * segment descriptor's length field. */
  	while (packetlen >= 2) {
  		u_int   segtype = data[0];
  		u_int   segsize = data[1];
  
  		/* Now that we know how long it claims to be, make sure
  		 * there is enough data for the next seg. */
  		if (packetlen < segsize + 2)
  			break;
  		switch (segtype) {
  		case 0x01:
  		case 0x51:
  			if (resptype_seen) {
  				log(LOG_WARNING, "nglmi: dup MSGTYPE\n");
  				goto nextIE;
  			}
  			resptype_seen++;
  			/* The remote end tells us what kind of response
  			 * this is. Only expect a type 0 or 1. if we are a
  			 * full status, invalidate a few DLCIs just to see
  			 * that they are still ok. */
  			if (segsize != 1)
  				goto nextIE;
  			switch (data[2]) {
  			case 1:
  				/* partial status, do no extra processing */
  				break;
  			case 0:
  			    {
  				int     count = 0;
  				int     idx = sc->invalidx;
  
  				for (count = 0; count < 10; count++) {
  					if (idx > MAXDLCI)
  						idx = 0;
  					if (sc->dlci_state[idx] == DLCI_UP)
  						sc->dlci_state[idx] = DLCI_DOWN;
  					idx++;
  				}
  				sc->invalidx = idx;
  				/* we got and we wanted one. relax
  				 * now.. but don't reset to 0 if it
  				 * was unrequested. */
  				if (sc->livs > sc->liv_per_full)
  					sc->livs = 0;
  				break;
  			    }
  			}
  			break;
  		case 0x03:
  		case 0x53:
  			/* The remote tells us what it thinks the sequence
  			 * numbers are. If it's not size 2, it must be a
  			 * duplicate to have gotten this far, skip it. */
  			if (seq_seen != 0)	/* already seen seq numbers */
  				goto nextIE;
  			if (segsize != 2)
  				goto nextIE;
  			sc->remote_seq = data[2];
  			if (sc->local_seq == data[3]) {
  				sc->local_seq++;
  				sc->seq_retries = 0;
  				/* Note that all 3 Frame protocols seem to
  				 * not like 0 as a sequence number. */
  				if (sc->local_seq == 0)
  					sc->local_seq = 1;
  			}
  			break;
  		case 0x07:
  		case 0x57:
  			/* The remote tells us about a DLCI that it knows
  			 * about. There may be many of these in a single
  			 * status response */
  			switch (segsize) {
  			case 6:/* only on 'group of 4' */
  				dlci = ((u_short) data[2] & 0xff) << 8;
  				dlci |= (data[3] & 0xff);
  				if ((dlci < 1024) && (dlci > 0)) {
  				  /* XXX */
  				}
  				break;
  			case 3:
  				dlci = ((u_short) data[2] & 0x3f) << 4;
  				dlci |= ((data[3] & 0x78) >> 3);
  				if ((dlci < 1024) && (dlci > 0)) {
  					/* set up the bottom half of the
  					 * support for that dlci if it's not
  					 * already been done */
  					/* store this information somewhere */
  				}
  				break;
  			default:
  				goto nextIE;
  			}
  			if (sc->dlci_state[dlci] != DLCI_UP) {
  				/* bring new DLCI to life */
  				/* may do more here some day */
  				if (sc->dlci_state[dlci] != DLCI_DOWN)
  					log(LOG_INFO,
  					    "nglmi: DLCI %d became active\n",
  					    dlci);
  				sc->dlci_state[dlci] = DLCI_UP;
  			}
  			break;
  		}
  nextIE:
  		STEPBY(segsize + 2);
  	}
  	NG_FREE_DATA(m, meta);
  	return (0);
  
  drop:
  	NG_FREE_DATA(m, meta);
  	return (EINVAL);
  }
  
  /*
   * Check that a packet is entirely kosha.
   * return 1 of ok, and 0 if not.
   * All data is discarded if a 0 is returned.
   */
  static int
  nglmi_checkdata(hook_p hook, struct mbuf *m, meta_p meta)
  {
  	sc_p    sc = hook->node->private;
  	u_char *data;
  	u_short packetlen;
  	unsigned short dlci;
  	u_char  type;
  	u_char  nextbyte;
  	int     seq_seen = 0;
  	int     resptype_seen = 0;	/* 0 , 1 (partial) or 2 (full) */
  	int     highest_dlci = 0;
  
  	packetlen = m->m_hdr.mh_len;
  	data = mtod(m, u_char *);
  	if (*data != 0x03) {
  		log(LOG_WARNING, "nglmi: unexpected value in LMI(%d)\n", 1);
  		goto reject;
  	}
  	STEPBY(1);
  
  	/* look at the protocol ID */
  	nextbyte = *data;
  	if (sc->flags & SCF_AUTO) {
  		SETLMITYPE(sc, SCF_NOLMI);	/* start with a clean slate */
  		switch (nextbyte) {
  		case 0x8:
  			sc->protoID = 8;
  			break;
  		case 0x9:
  			SETLMITYPE(sc, SCF_GROUP4);
  			sc->protoID = 9;
  			break;
  		default:
  			log(LOG_WARNING, "nglmi: bad Protocol ID(%d)\n",
  			    (int) nextbyte);
  			goto reject;
  		}
  	} else {
  		if (nextbyte != sc->protoID) {
  			log(LOG_WARNING, "nglmi: unexpected Protocol ID(%d)\n",
  			    (int) nextbyte);
  			goto reject;
  		}
  	}
  	STEPBY(1);
  
  	/* check call reference (always null in non ISDN frame relay) */
  	if (*data != 0x00) {
  		log(LOG_WARNING, "nglmi: unexpected Call Reference (0x%x)\n",
  		    data[-1]);
  		goto reject;
  	}
  	STEPBY(1);
  
  	/* check message type */
  	switch ((type = *data)) {
  	case 0x75:		/* Status enquiry */
  		log(LOG_WARNING, "nglmi: unexpected message type(0x%x)\n",
  		    data[-1]);
  		goto reject;
  	case 0x7D:		/* Status message */
  		break;
  	default:
  		log(LOG_WARNING,
  		    "nglmi: unexpected msg type(0x%x) \n", (int) type);
  		goto reject;
  	}
  	STEPBY(1);
  
  	/* Now check if there is a 'locking shift'. This is only seen in
  	 * Annex D frames. Don't increment immediately as it might not be
  	 * there. */
  	nextbyte = *data;
  	if (sc->flags & SCF_AUTO) {
  		if (!(GROUP4(sc))) {
  			if (nextbyte == 0x95) {
  				SETLMITYPE(sc, SCF_ANNEX_D);
  				STEPBY(1);
  			} else
  				SETLMITYPE(sc, SCF_ANNEX_A);
  		} else if (nextbyte == 0x95) {
  			log(LOG_WARNING, "nglmi: locking shift seen in G4\n");
  			goto reject;
  		}
  	} else {
  		if (ANNEXD(sc)) {
  			if (*data == 0x95)
  				STEPBY(1);
  			else {
  				log(LOG_WARNING,
  				    "nglmi: locking shift missing\n");
  				goto reject;
  			}
  		} else if (*data == 0x95) {
  			log(LOG_WARNING, "nglmi: locking shift seen\n");
  			goto reject;
  		}
  	}
  
  	/* While there is more data in the status packet, keep processing
  	 * status items. First make sure there is enough data for the
  	 * segment descriptor's length field. */
  	while (packetlen >= 2) {
  		u_int   segtype = data[0];
  		u_int   segsize = data[1];
  
  		/* Now that we know how long it claims to be, make sure
  		 * there is enough data for the next seg. */
  		if (packetlen < (segsize + 2)) {
  			log(LOG_WARNING, "nglmi: IE longer than packet\n");
  			break;
  		}
  		switch (segtype) {
  		case 0x01:
  		case 0x51:
  			/* According to MCI's HP analyser, we should just
  			 * ignore if there is mor ethan one of these (?). */
  			if (resptype_seen) {
  				log(LOG_WARNING, "nglmi: dup MSGTYPE\n");
  				goto nextIE;
  			}
  			if (segsize != 1) {
  				log(LOG_WARNING, "nglmi: MSGTYPE wrong size\n");
  				goto reject;
  			}
  			/* The remote end tells us what kind of response
  			 * this is. Only expect a type 0 or 1. if it was a
  			 * full (type 0) check we just asked for a type
  			 * full. */
  			switch (data[2]) {
  			case 1:/* partial */
  				if (sc->livs > sc->liv_per_full) {
  					log(LOG_WARNING,
  					  "nglmi: LIV when FULL expected\n");
  					goto reject;	/* need full */
  				}
  				resptype_seen = 1;
  				break;
  			case 0:/* full */
  				/* Full response is always acceptable */
  				resptype_seen = 2;
  				break;
  			default:
  				log(LOG_WARNING,
  				 "nglmi: Unknown report type %d\n", data[2]);
  				goto reject;
  			}
  			break;
  		case 0x03:
  		case 0x53:
  			/* The remote tells us what it thinks the sequence
  			 * numbers are. I would have thought that there
  			 * needs to be one and only one of these, but MCI
  			 * want us to just ignore extras. (?) */
  			if (resptype_seen == 0) {
  				log(LOG_WARNING, "nglmi: no TYPE before SEQ\n");
  				goto reject;
  			}
  			if (seq_seen != 0)	/* already seen seq numbers */
  				goto nextIE;
  			if (segsize != 2) {
  				log(LOG_WARNING, "nglmi: bad SEQ sts size\n");
  				goto reject;
  			}
  			if (sc->local_seq != data[3]) {
  				log(LOG_WARNING, "nglmi: unexpected SEQ\n");
  				goto reject;
  			}
  			seq_seen = 1;
  			break;
  		case 0x07:
  		case 0x57:
  			/* The remote tells us about a DLCI that it knows
  			 * about. There may be many of these in a single
  			 * status response */
  			if (seq_seen != 1) {	/* already seen seq numbers? */
  				log(LOG_WARNING,
  				    "nglmi: No sequence before DLCI\n");
  				goto reject;
  			}
  			if (resptype_seen != 2) {	/* must be full */
  				log(LOG_WARNING,
  				    "nglmi: No resp type before DLCI\n");
  				goto reject;
  			}
  			if (GROUP4(sc)) {
  				if (segsize != 6) {
  					log(LOG_WARNING,
  					    "nglmi: wrong IE segsize\n");
  					goto reject;
  				}
  				dlci = ((u_short) data[2] & 0xff) << 8;
  				dlci |= (data[3] & 0xff);
  			} else {
  				if (segsize != 3) {
  					log(LOG_WARNING,
  					    "nglmi: DLCI headersize of %d"
  					    " not supported\n", segsize - 1);
  					goto reject;
  				}
  				dlci = ((u_short) data[2] & 0x3f) << 4;
  				dlci |= ((data[3] & 0x78) >> 3);
  			}
  			/* async can only have one of these */
  #if 0				/* async not yet accepted */
  			if (async && highest_dlci) {
  				log(LOG_WARNING,
  				    "nglmi: Async with > 1 DLCI\n");
  				goto reject;
  			}
  #endif
  			/* Annex D says these will always be Ascending, but
  			 * the HP test for G4 says we should accept
  			 * duplicates, so for now allow that. ( <= vs. < ) */
  #if 0
  			/* MCI tests want us to accept out of order for AnxD */
  			if ((!GROUP4(sc)) && (dlci < highest_dlci)) {
  				/* duplicate or mis-ordered dlci */
  				/* (spec says they will increase in number) */
  				log(LOG_WARNING, "nglmi: DLCI out of order\n");
  				goto reject;
  			}
  #endif
  			if (dlci > 1023) {
  				log(LOG_WARNING, "nglmi: DLCI out of range\n");
  				goto reject;
  			}
  			highest_dlci = dlci;
  			break;
  		default:
  			log(LOG_WARNING,
  			    "nglmi: unknown LMI segment type %d\n", segtype);
  		}
  nextIE:
  		STEPBY(segsize + 2);
  	}
  	if (packetlen != 0) {	/* partial junk at end? */
  		log(LOG_WARNING,
  		    "nglmi: %d bytes extra at end of packet\n", packetlen);
  		goto print;
  	}
  	if (resptype_seen == 0) {
  		log(LOG_WARNING, "nglmi: No response type seen\n");
  		goto reject;	/* had no response type */
  	}
  	if (seq_seen == 0) {
  		log(LOG_WARNING, "nglmi: No sequence numbers seen\n");
  		goto reject;	/* had no sequence numbers */
  	}
  	return (1);
  
  print:
  	{
  		int     i, j, k, pos;
  		char    buf[100];
  		int     loc;
  		u_char *bp = mtod(m, u_char *);
  
  		k = i = 0;
  		loc = (m->m_hdr.mh_len - packetlen);
  		log(LOG_WARNING, "nglmi: error at location %d\n", loc);
  		while (k < m->m_hdr.mh_len) {
  			pos = 0;
  			j = 0;
  			while ((j++ < 16) && k < m->m_hdr.mh_len) {
  				pos += sprintf(buf + pos, "%c%02x",
  					       ((loc == k) ? '>' : ' '),
  					       bp[k]);
  				k++;
  			}
  			if (i == 0)
  				log(LOG_WARNING, "nglmi: packet data:%s\n", buf);
  			else
  				log(LOG_WARNING, "%04d              :%s\n", k, buf);
  			i++;
  		}
  	}
  	return (1);
  reject:
  	{
  		int     i, j, k, pos;
  		char    buf[100];
  		int     loc;
  		u_char *bp = mtod(m, u_char *);
  
  		k = i = 0;
  		loc = (m->m_hdr.mh_len - packetlen);
  		log(LOG_WARNING, "nglmi: error at location %d\n", loc);
  		while (k < m->m_hdr.mh_len) {
  			pos = 0;
  			j = 0;
  			while ((j++ < 16) && k < m->m_hdr.mh_len) {
  				pos += sprintf(buf + pos, "%c%02x",
  					       ((loc == k) ? '>' : ' '),
  					       bp[k]);
  				k++;
  			}
  			if (i == 0)
  				log(LOG_WARNING, "nglmi: packet data:%s\n", buf);
  			else
  				log(LOG_WARNING, "%04d              :%s\n", k, buf);
  			i++;
  		}
  	}
  	NG_FREE_DATA(m, meta);
  	return (0);
  }
  
  /*
   * Do local shutdown processing..
   * Cut any remaining links and free our local resources.
   */
  static int
  nglmi_rmnode(node_p node)
  {
  	const sc_p sc = node->private;
  
  	node->flags |= NG_INVALID;
  	ng_cutlinks(node);
  	ng_unname(node);
  	node->private = NULL;
  	ng_unref(sc->node);
  	FREE(sc, M_NETGRAPH);
  	return (0);
  }
  
  /*
   * Hook disconnection
   * For this type, removal of any link except "debug" destroys the node.
   */
  static int
  nglmi_disconnect(hook_p hook)
  {
  	const sc_p sc = hook->node->private;
  
  	/* OK to remove debug hook(s) */
  	if (hook->private == NULL)
  		return (0);
  
  	/* Stop timer if it's currently active */
  	if (sc->flags & SCF_CONNECTED)
  		untimeout(LMI_ticker, sc, sc->handle);
  
  	/* Self-destruct */
  	ng_rmnode(hook->node);
  	return (0);
  }
  
  