xref: /freebsd/sys/netgraph/ng_cisco.c (revision 95ee2897e98f5d444f26ed2334cc7c439f9c16c6)
1 /*
2  * ng_cisco.c
3  */
4 
5 /*-
6  * Copyright (c) 1996-1999 Whistle Communications, Inc.
7  * All rights reserved.
8  *
9  * Subject to the following obligations and disclaimer of warranty, use and
10  * redistribution of this software, in source or object code forms, with or
11  * without modifications are expressly permitted by Whistle Communications;
12  * provided, however, that:
13  * 1. Any and all reproductions of the source or object code must include the
14  *    copyright notice above and the following disclaimer of warranties; and
15  * 2. No rights are granted, in any manner or form, to use Whistle
16  *    Communications, Inc. trademarks, including the mark "WHISTLE
17  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
18  *    such appears in the above copyright notice or in the software.
19  *
20  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
21  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
22  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
23  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
24  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
25  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
26  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
27  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
28  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
29  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
30  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
31  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
32  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
36  * OF SUCH DAMAGE.
37  *
38  * Author: Julian Elischer <julian@freebsd.org>
39  * $Whistle: ng_cisco.c,v 1.25 1999/11/01 09:24:51 julian Exp $
40  */
41 
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/errno.h>
45 #include <sys/kernel.h>
46 #include <sys/socket.h>
47 #include <sys/malloc.h>
48 #include <sys/mbuf.h>
49 #include <sys/syslog.h>
50 
51 #include <net/if.h>
52 
53 #include <netinet/in.h>
54 #include <netinet/if_ether.h>
55 
56 #include <netgraph/ng_message.h>
57 #include <netgraph/netgraph.h>
58 #include <netgraph/ng_parse.h>
59 #include <netgraph/ng_cisco.h>
60 
61 #define	CISCO_MULTICAST		0x8f	/* Cisco multicast address */
62 #define	CISCO_UNICAST		0x0f	/* Cisco unicast address */
63 #define	CISCO_KEEPALIVE		0x8035	/* Cisco keepalive protocol */
64 #define	CISCO_ADDR_REQ		0	/* Cisco address request */
65 #define	CISCO_ADDR_REPLY	1	/* Cisco address reply */
66 #define	CISCO_KEEPALIVE_REQ	2	/* Cisco keepalive request */
67 
68 #define KEEPALIVE_SECS		10
69 
70 struct cisco_header {
71 	uint8_t  address;
72 	uint8_t  control;
73 	uint16_t protocol;
74 } __packed;
75 
76 #define	CISCO_HEADER_LEN	sizeof (struct cisco_header)
77 
78 struct cisco_packet {
79 	uint32_t type;
80 	uint32_t par1;
81 	uint32_t par2;
82 	uint16_t rel;
83 	uint16_t time0;
84 	uint16_t time1;
85 } __packed;
86 
87 #define	CISCO_PACKET_LEN (sizeof(struct cisco_packet))
88 
89 struct protoent {
90 	hook_p  hook;		/* the hook for this proto */
91 	uint16_t af;		/* address family, -1 = downstream */
92 };
93 
94 struct cisco_priv {
95 	uint32_t local_seq;
96 	uint32_t remote_seq;
97 	uint32_t seqRetries;	/* how many times we've been here throwing out
98 				 * the same sequence number without ack */
99 	node_p  node;
100 	struct callout handle;
101 	struct protoent downstream;
102 	struct protoent inet;		/* IP information */
103 	struct in_addr localip;
104 	struct in_addr localmask;
105 	struct protoent inet6;		/* IPv6 information */
106 	struct protoent atalk;		/* AppleTalk information */
107 	struct protoent ipx;		/* IPX information */
108 };
109 typedef struct cisco_priv *sc_p;
110 
111 /* Netgraph methods */
112 static ng_constructor_t		cisco_constructor;
113 static ng_rcvmsg_t		cisco_rcvmsg;
114 static ng_shutdown_t		cisco_shutdown;
115 static ng_newhook_t		cisco_newhook;
116 static ng_rcvdata_t		cisco_rcvdata;
117 static ng_disconnect_t		cisco_disconnect;
118 
119 /* Other functions */
120 static int	cisco_input(sc_p sc, item_p item);
121 static void	cisco_keepalive(node_p node, hook_p hook, void *arg1, int arg2);
122 static int	cisco_send(sc_p sc, int type, long par1, long par2);
123 static void	cisco_notify(sc_p sc, uint32_t cmd);
124 
125 /* Parse type for struct ng_cisco_ipaddr */
126 static const struct ng_parse_struct_field ng_cisco_ipaddr_type_fields[]
127 	= NG_CISCO_IPADDR_TYPE_INFO;
128 static const struct ng_parse_type ng_cisco_ipaddr_type = {
129 	&ng_parse_struct_type,
130 	&ng_cisco_ipaddr_type_fields
131 };
132 
133 /* Parse type for struct ng_async_stat */
134 static const struct ng_parse_struct_field ng_cisco_stats_type_fields[]
135 	= NG_CISCO_STATS_TYPE_INFO;
136 static const struct ng_parse_type ng_cisco_stats_type = {
137 	&ng_parse_struct_type,
138 	&ng_cisco_stats_type_fields
139 };
140 
141 /* List of commands and how to convert arguments to/from ASCII */
142 static const struct ng_cmdlist ng_cisco_cmdlist[] = {
143 	{
144 	  NGM_CISCO_COOKIE,
145 	  NGM_CISCO_SET_IPADDR,
146 	  "setipaddr",
147 	  &ng_cisco_ipaddr_type,
148 	  NULL
149 	},
150 	{
151 	  NGM_CISCO_COOKIE,
152 	  NGM_CISCO_GET_IPADDR,
153 	  "getipaddr",
154 	  NULL,
155 	  &ng_cisco_ipaddr_type
156 	},
157 	{
158 	  NGM_CISCO_COOKIE,
159 	  NGM_CISCO_GET_STATUS,
160 	  "getstats",
161 	  NULL,
162 	  &ng_cisco_stats_type
163 	},
164 	{ 0 }
165 };
166 
167 /* Node type */
168 static struct ng_type typestruct = {
169 	.version =	NG_ABI_VERSION,
170 	.name =		NG_CISCO_NODE_TYPE,
171 	.constructor =	cisco_constructor,
172 	.rcvmsg =	cisco_rcvmsg,
173 	.shutdown =	cisco_shutdown,
174 	.newhook =	cisco_newhook,
175 	.rcvdata =	cisco_rcvdata,
176 	.disconnect =	cisco_disconnect,
177 	.cmdlist =	ng_cisco_cmdlist,
178 };
179 NETGRAPH_INIT(cisco, &typestruct);
180 
181 /*
182  * Node constructor
183  */
184 static int
cisco_constructor(node_p node)185 cisco_constructor(node_p node)
186 {
187 	sc_p sc;
188 
189 	sc = malloc(sizeof(*sc), M_NETGRAPH, M_WAITOK | M_ZERO);
190 
191 	ng_callout_init(&sc->handle);
192 	NG_NODE_SET_PRIVATE(node, sc);
193 	sc->node = node;
194 
195 	/* Initialise the varous protocol hook holders */
196 	sc->downstream.af = 0xffff;
197 	sc->inet.af = AF_INET;
198 	sc->inet6.af = AF_INET6;
199 	sc->atalk.af = AF_APPLETALK;
200 	sc->ipx.af = AF_IPX;
201 	return (0);
202 }
203 
204 /*
205  * Check new hook
206  */
207 static int
cisco_newhook(node_p node,hook_p hook,const char * name)208 cisco_newhook(node_p node, hook_p hook, const char *name)
209 {
210 	const sc_p sc = NG_NODE_PRIVATE(node);
211 
212 	if (strcmp(name, NG_CISCO_HOOK_DOWNSTREAM) == 0) {
213 		sc->downstream.hook = hook;
214 		NG_HOOK_SET_PRIVATE(hook, &sc->downstream);
215 
216 		/* Start keepalives */
217 		ng_callout(&sc->handle, node, NULL, (hz * KEEPALIVE_SECS),
218 		    &cisco_keepalive, (void *)sc, 0);
219 	} else if (strcmp(name, NG_CISCO_HOOK_INET) == 0) {
220 		sc->inet.hook = hook;
221 		NG_HOOK_SET_PRIVATE(hook, &sc->inet);
222 	} else if (strcmp(name, NG_CISCO_HOOK_INET6) == 0) {
223 		sc->inet6.hook = hook;
224 		NG_HOOK_SET_PRIVATE(hook, &sc->inet6);
225 	} else if (strcmp(name, NG_CISCO_HOOK_APPLETALK) == 0) {
226 		sc->atalk.hook = hook;
227 		NG_HOOK_SET_PRIVATE(hook, &sc->atalk);
228 	} else if (strcmp(name, NG_CISCO_HOOK_IPX) == 0) {
229 		sc->ipx.hook = hook;
230 		NG_HOOK_SET_PRIVATE(hook, &sc->ipx);
231 	} else if (strcmp(name, NG_CISCO_HOOK_DEBUG) == 0) {
232 		NG_HOOK_SET_PRIVATE(hook, NULL);	/* unimplemented */
233 	} else
234 		return (EINVAL);
235 	return 0;
236 }
237 
238 /*
239  * Receive control message.
240  */
241 static int
cisco_rcvmsg(node_p node,item_p item,hook_p lasthook)242 cisco_rcvmsg(node_p node, item_p item, hook_p lasthook)
243 {
244 	struct ng_mesg *msg;
245 	const sc_p sc = NG_NODE_PRIVATE(node);
246 	struct ng_mesg *resp = NULL;
247 	int error = 0;
248 
249 	NGI_GET_MSG(item, msg);
250 	switch (msg->header.typecookie) {
251 	case NGM_GENERIC_COOKIE:
252 		switch (msg->header.cmd) {
253 		case NGM_TEXT_STATUS:
254 		    {
255 			char *arg;
256 			int pos;
257 
258 			NG_MKRESPONSE(resp, msg, NG_TEXTRESPONSE, M_NOWAIT);
259 			if (resp == NULL) {
260 				error = ENOMEM;
261 				break;
262 			}
263 			arg = (char *) resp->data;
264 			pos = sprintf(arg,
265 			  "keepalive period: %d sec; ", KEEPALIVE_SECS);
266 			pos += sprintf(arg + pos,
267 			  "unacknowledged keepalives: %d", sc->seqRetries);
268 			resp->header.arglen = pos + 1;
269 			break;
270 		    }
271 		default:
272 			error = EINVAL;
273 			break;
274 		}
275 		break;
276 	case NGM_CISCO_COOKIE:
277 		switch (msg->header.cmd) {
278 		case NGM_CISCO_GET_IPADDR:	/* could be a late reply! */
279 			if ((msg->header.flags & NGF_RESP) == 0) {
280 				struct in_addr *ips;
281 
282 				NG_MKRESPONSE(resp, msg,
283 				    2 * sizeof(*ips), M_NOWAIT);
284 				if (!resp) {
285 					error = ENOMEM;
286 					break;
287 				}
288 				ips = (struct in_addr *) resp->data;
289 				ips[0] = sc->localip;
290 				ips[1] = sc->localmask;
291 				break;
292 			}
293 			/* FALLTHROUGH */	/* ...if it's a reply */
294 		case NGM_CISCO_SET_IPADDR:
295 		    {
296 			struct in_addr *const ips = (struct in_addr *)msg->data;
297 
298 			if (msg->header.arglen < 2 * sizeof(*ips)) {
299 				error = EINVAL;
300 				break;
301 			}
302 			sc->localip = ips[0];
303 			sc->localmask = ips[1];
304 			break;
305 		    }
306 		case NGM_CISCO_GET_STATUS:
307 		    {
308 			struct ng_cisco_stats *stat;
309 
310 			NG_MKRESPONSE(resp, msg, sizeof(*stat), M_NOWAIT);
311 			if (!resp) {
312 				error = ENOMEM;
313 				break;
314 			}
315 			stat = (struct ng_cisco_stats *)resp->data;
316 			stat->seqRetries = sc->seqRetries;
317 			stat->keepAlivePeriod = KEEPALIVE_SECS;
318 			break;
319 		    }
320 		default:
321 			error = EINVAL;
322 			break;
323 		}
324 		break;
325 	default:
326 		error = EINVAL;
327 		break;
328 	}
329 	NG_RESPOND_MSG(error, node, item, resp);
330 	NG_FREE_MSG(msg);
331 	return (error);
332 }
333 
334 /*
335  * Receive data
336  */
337 static int
cisco_rcvdata(hook_p hook,item_p item)338 cisco_rcvdata(hook_p hook, item_p item)
339 {
340 	const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
341 	struct protoent *pep;
342 	struct cisco_header *h;
343 	struct mbuf *m;
344 	int error = 0;
345 
346 	if ((pep = NG_HOOK_PRIVATE(hook)) == NULL)
347 		goto out;
348 
349 	/* If it came from our downlink, deal with it separately */
350 	if (pep->af == 0xffff)
351 		return (cisco_input(sc, item));
352 
353 	/* OK so it came from a protocol, heading out. Prepend general data
354 	   packet header. For now, IP,IPX only  */
355 	NGI_GET_M(item, m);
356 	M_PREPEND(m, CISCO_HEADER_LEN, M_NOWAIT);
357 	if (!m) {
358 		error = ENOBUFS;
359 		goto out;
360 	}
361 	NGI_M(item) = m;
362 	h = mtod(m, struct cisco_header *);
363 	h->address = CISCO_UNICAST;
364 	h->control = 0;
365 
366 	switch (pep->af) {
367 	case AF_INET:		/* Internet Protocol */
368 		h->protocol = htons(ETHERTYPE_IP);
369 		break;
370 	case AF_INET6:
371 		h->protocol = htons(ETHERTYPE_IPV6);
372 		break;
373 	case AF_APPLETALK:	/* AppleTalk Protocol */
374 		h->protocol = htons(ETHERTYPE_AT);
375 		break;
376 	case AF_IPX:		/* Novell IPX Protocol */
377 		h->protocol = htons(ETHERTYPE_IPX);
378 		break;
379 	default:
380 		error = EAFNOSUPPORT;
381 		goto out;
382 	}
383 
384 	/* Send it */
385 	NG_FWD_NEW_DATA(error, item,  sc->downstream.hook, m);
386 	return (error);
387 
388 out:
389 	NG_FREE_ITEM(item);
390 	return (error);
391 }
392 
393 /*
394  * Shutdown node
395  */
396 static int
cisco_shutdown(node_p node)397 cisco_shutdown(node_p node)
398 {
399 	const sc_p sc = NG_NODE_PRIVATE(node);
400 
401 	NG_NODE_SET_PRIVATE(node, NULL);
402 	NG_NODE_UNREF(sc->node);
403 	free(sc, M_NETGRAPH);
404 	return (0);
405 }
406 
407 /*
408  * Disconnection of a hook
409  *
410  * For this type, removal of the last link destroys the node
411  */
412 static int
cisco_disconnect(hook_p hook)413 cisco_disconnect(hook_p hook)
414 {
415 	const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
416 	struct protoent *pep;
417 
418 	/* Check it's not the debug hook */
419 	if ((pep = NG_HOOK_PRIVATE(hook))) {
420 		pep->hook = NULL;
421 		if (pep->af == 0xffff)
422 			/* If it is the downstream hook, stop the timers */
423 			ng_uncallout(&sc->handle, NG_HOOK_NODE(hook));
424 	}
425 
426 	/* If no more hooks, remove the node */
427 	if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
428 	&& (NG_NODE_IS_VALID(NG_HOOK_NODE(hook))))
429 		ng_rmnode_self(NG_HOOK_NODE(hook));
430 	return (0);
431 }
432 
433 /*
434  * Receive data
435  */
436 static int
cisco_input(sc_p sc,item_p item)437 cisco_input(sc_p sc, item_p item)
438 {
439 	const struct cisco_header *h;
440 	struct cisco_header hdrbuf;
441 	struct protoent *pep;
442 	struct mbuf *m;
443 	int error = 0;
444 
445 	/* Get data */
446 	m = NGI_M(item);
447 
448 	/* Sanity check header length */
449 	if (m->m_pkthdr.len < sizeof(*h)) {
450 		error = EINVAL;
451 		goto drop;
452 	}
453 
454 	/* Get cisco header */
455 	if (m->m_len >= sizeof(*h))			/* the common case */
456 		h = mtod(m, const struct cisco_header *);
457 	else {
458 		m_copydata(m, 0, sizeof(*h), (caddr_t)&hdrbuf);
459 		h = &hdrbuf;
460 	}
461 	m_adj(m, sizeof(*h));
462 
463 	/* Check header address */
464 	switch (h->address) {
465 	default:		/* Invalid Cisco packet. */
466 		goto drop;
467 	case CISCO_UNICAST:
468 	case CISCO_MULTICAST:
469 		/* Don't check the control field here (RFC 1547). */
470 		switch (ntohs(h->protocol)) {
471 		default:
472 			goto drop;
473 		case CISCO_KEEPALIVE:
474 		    {
475 			const struct cisco_packet *p;
476 			struct cisco_packet pktbuf;
477 
478 			/* Sanity check packet length */
479 			if (m->m_pkthdr.len < sizeof(*p)) {
480 				error = EINVAL;
481 				goto drop;
482 			}
483 
484 			/* Get cisco packet */
485 			if (m->m_len >= sizeof(*p))	/* the common case */
486 				p = mtod(m, const struct cisco_packet *);
487 			else {
488 				m_copydata(m, 0, sizeof(*p), (caddr_t)&pktbuf);
489 				p = &pktbuf;
490 			}
491 
492 			/* Check packet type */
493 			switch (ntohl(p->type)) {
494 			default:
495 				log(LOG_WARNING,
496 				    "cisco: unknown cisco packet type: 0x%lx\n",
497 				       (long)ntohl(p->type));
498 				break;
499 			case CISCO_ADDR_REPLY:
500 				/* Reply on address request, ignore */
501 				break;
502 			case CISCO_KEEPALIVE_REQ:
503 				sc->remote_seq = ntohl(p->par1);
504 				if (sc->local_seq == ntohl(p->par2)) {
505 					sc->local_seq++;
506 					if (sc->seqRetries > 1)
507 						cisco_notify(sc, NGM_LINK_IS_UP);
508 					sc->seqRetries = 0;
509 				}
510 				break;
511 			case CISCO_ADDR_REQ:
512 			    {
513 				struct ng_mesg *msg;
514 				int dummy_error = 0;
515 
516 				/* Ask inet peer for IP address information */
517 				if (sc->inet.hook == NULL)
518 					goto nomsg;
519 				NG_MKMESSAGE(msg, NGM_CISCO_COOKIE,
520 				    NGM_CISCO_GET_IPADDR, 0, M_NOWAIT);
521 				if (msg == NULL)
522 					goto nomsg;
523 				NG_SEND_MSG_HOOK(dummy_error,
524 				    sc->node, msg, sc->inet.hook, 0);
525 		/*
526 		 * XXX Now maybe we should set a flag telling
527 		 * our receiver to send this message when the response comes in
528 		 * instead of now when the data may be bad.
529 		 */
530 		nomsg:
531 				/* Send reply to peer device */
532 				error = cisco_send(sc, CISCO_ADDR_REPLY,
533 					    ntohl(sc->localip.s_addr),
534 					    ntohl(sc->localmask.s_addr));
535 				break;
536 			    }
537 			}
538 			goto drop;
539 		    }
540 		case ETHERTYPE_IP:
541 			pep = &sc->inet;
542 			break;
543 		case ETHERTYPE_IPV6:
544 			pep = &sc->inet6;
545 			break;
546 		case ETHERTYPE_AT:
547 			pep = &sc->atalk;
548 			break;
549 		case ETHERTYPE_IPX:
550 			pep = &sc->ipx;
551 			break;
552 		}
553 		break;
554 	}
555 
556 	/* Drop if payload is empty */
557 	if (m->m_pkthdr.len == 0) {
558 		error = EINVAL;
559 		goto drop;
560 	}
561 
562 	/* Send it on */
563 	if (pep->hook == NULL)
564 		goto drop;
565 	NG_FWD_NEW_DATA(error, item, pep->hook, m);
566 	return (error);
567 
568 drop:
569 	NG_FREE_ITEM(item);
570 	return (error);
571 }
572 
573 /*
574  * Send keepalive packets, every 10 seconds.
575  */
576 static void
cisco_keepalive(node_p node,hook_p hook,void * arg1,int arg2)577 cisco_keepalive(node_p node, hook_p hook, void *arg1, int arg2)
578 {
579 	const sc_p sc = arg1;
580 
581 	cisco_send(sc, CISCO_KEEPALIVE_REQ, sc->local_seq, sc->remote_seq);
582 	if (sc->seqRetries++ > 1)
583 		cisco_notify(sc, NGM_LINK_IS_DOWN);
584 	ng_callout(&sc->handle, node, NULL, (hz * KEEPALIVE_SECS),
585 	    &cisco_keepalive, (void *)sc, 0);
586 }
587 
588 /*
589  * Send Cisco keepalive packet.
590  */
591 static int
cisco_send(sc_p sc,int type,long par1,long par2)592 cisco_send(sc_p sc, int type, long par1, long par2)
593 {
594 	struct cisco_header *h;
595 	struct cisco_packet *ch;
596 	struct mbuf *m;
597 	struct timeval time;
598 	uint32_t t;
599 	int     error = 0;
600 
601 	getmicrouptime(&time);
602 
603 	MGETHDR(m, M_NOWAIT, MT_DATA);
604 	if (!m)
605 		return (ENOBUFS);
606 
607 	t = time.tv_sec * 1000 + time.tv_usec / 1000;
608 	m->m_pkthdr.len = m->m_len = CISCO_HEADER_LEN + CISCO_PACKET_LEN;
609 	m->m_pkthdr.rcvif = 0;
610 
611 	h = mtod(m, struct cisco_header *);
612 	h->address = CISCO_MULTICAST;
613 	h->control = 0;
614 	h->protocol = htons(CISCO_KEEPALIVE);
615 
616 	ch = (struct cisco_packet *) (h + 1);
617 	ch->type = htonl(type);
618 	ch->par1 = htonl(par1);
619 	ch->par2 = htonl(par2);
620 	ch->rel = -1;
621 	ch->time0 = htons((uint16_t) (t >> 16));
622 	ch->time1 = htons((uint16_t) t);
623 
624 	NG_SEND_DATA_ONLY(error, sc->downstream.hook, m);
625 	return (error);
626 }
627 
628 /*
629  * Send linkstate to upstream node.
630  */
631 static void
cisco_notify(sc_p sc,uint32_t cmd)632 cisco_notify(sc_p sc, uint32_t cmd)
633 {
634 	struct ng_mesg *msg;
635 	int dummy_error = 0;
636 
637 	if (sc->inet.hook == NULL) /* nothing to notify */
638 		return;
639 
640 	NG_MKMESSAGE(msg, NGM_FLOW_COOKIE, cmd, 0, M_NOWAIT);
641 	if (msg != NULL)
642 		NG_SEND_MSG_HOOK(dummy_error, sc->node, msg, sc->inet.hook, 0);
643 }
644