xref: /freebsd/sys/netgraph/ng_patch.c (revision ebacd8013fe5f7fdf9f6a5b286f6680dd2891036)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2010 Maxim Ignatenko <gelraen.ua@gmail.com>
5  * Copyright (c) 2015 Dmitry Vagin <daemon.hammer@ya.ru>
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  */
30 
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33 
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/endian.h>
38 #include <sys/malloc.h>
39 #include <sys/mbuf.h>
40 
41 #include <net/bpf.h>
42 #include <net/ethernet.h>
43 
44 #include <netgraph/ng_message.h>
45 #include <netgraph/ng_parse.h>
46 #include <netgraph/netgraph.h>
47 
48 #include <netgraph/ng_patch.h>
49 
50 /* private data */
51 struct ng_patch_priv {
52 	hook_p		in;
53 	hook_p		out;
54 	uint8_t		dlt;	/* DLT_XXX from bpf.h */
55 	struct ng_patch_stats stats;
56 	struct ng_patch_config *conf;
57 };
58 
59 typedef struct ng_patch_priv *priv_p;
60 
61 /* Netgraph methods */
62 static ng_constructor_t	ng_patch_constructor;
63 static ng_rcvmsg_t	ng_patch_rcvmsg;
64 static ng_shutdown_t	ng_patch_shutdown;
65 static ng_newhook_t	ng_patch_newhook;
66 static ng_rcvdata_t	ng_patch_rcvdata;
67 static ng_disconnect_t	ng_patch_disconnect;
68 #define ERROUT(x) { error = (x); goto done; }
69 
70 static int
71 ng_patch_config_getlen(const struct ng_parse_type *type,
72     const u_char *start, const u_char *buf)
73 {
74 	const struct ng_patch_config *conf;
75 
76 	conf = (const struct ng_patch_config *)(buf -
77 	    offsetof(struct ng_patch_config, ops));
78 
79 	return (conf->count);
80 }
81 
82 static const struct ng_parse_struct_field ng_patch_op_type_fields[]
83 	= NG_PATCH_OP_TYPE;
84 static const struct ng_parse_type ng_patch_op_type = {
85 	&ng_parse_struct_type,
86 	&ng_patch_op_type_fields
87 };
88 
89 static const struct ng_parse_array_info ng_patch_ops_array_info = {
90 	&ng_patch_op_type,
91 	&ng_patch_config_getlen
92 };
93 static const struct ng_parse_type ng_patch_ops_array_type = {
94 	&ng_parse_array_type,
95 	&ng_patch_ops_array_info
96 };
97 
98 static const struct ng_parse_struct_field ng_patch_config_type_fields[]
99 	= NG_PATCH_CONFIG_TYPE;
100 static const struct ng_parse_type ng_patch_config_type = {
101 	&ng_parse_struct_type,
102 	&ng_patch_config_type_fields
103 };
104 
105 static const struct ng_parse_struct_field ng_patch_stats_fields[]
106 	= NG_PATCH_STATS_TYPE;
107 static const struct ng_parse_type ng_patch_stats_type = {
108 	&ng_parse_struct_type,
109 	&ng_patch_stats_fields
110 };
111 
112 static const struct ng_cmdlist ng_patch_cmdlist[] = {
113 	{
114 		NGM_PATCH_COOKIE,
115 		NGM_PATCH_GETDLT,
116 		"getdlt",
117 		NULL,
118 		&ng_parse_uint8_type
119 	},
120 	{
121 		NGM_PATCH_COOKIE,
122 		NGM_PATCH_SETDLT,
123 		"setdlt",
124 		&ng_parse_uint8_type,
125 		NULL
126 	},
127 	{
128 		NGM_PATCH_COOKIE,
129 		NGM_PATCH_GETCONFIG,
130 		"getconfig",
131 		NULL,
132 		&ng_patch_config_type
133 	},
134 	{
135 		NGM_PATCH_COOKIE,
136 		NGM_PATCH_SETCONFIG,
137 		"setconfig",
138 		&ng_patch_config_type,
139 		NULL
140 	},
141 	{
142 		NGM_PATCH_COOKIE,
143 		NGM_PATCH_GET_STATS,
144 		"getstats",
145 		NULL,
146 		&ng_patch_stats_type
147 	},
148 	{
149 		NGM_PATCH_COOKIE,
150 		NGM_PATCH_CLR_STATS,
151 		"clrstats",
152 		NULL,
153 		NULL
154 	},
155 	{
156 		NGM_PATCH_COOKIE,
157 		NGM_PATCH_GETCLR_STATS,
158 		"getclrstats",
159 		NULL,
160 		&ng_patch_stats_type
161 	},
162 	{ 0 }
163 };
164 
165 static struct ng_type typestruct = {
166 	.version =	NG_ABI_VERSION,
167 	.name =		NG_PATCH_NODE_TYPE,
168 	.constructor =	ng_patch_constructor,
169 	.rcvmsg =	ng_patch_rcvmsg,
170 	.shutdown =	ng_patch_shutdown,
171 	.newhook =	ng_patch_newhook,
172 	.rcvdata =	ng_patch_rcvdata,
173 	.disconnect =	ng_patch_disconnect,
174 	.cmdlist =	ng_patch_cmdlist,
175 };
176 
177 NETGRAPH_INIT(patch, &typestruct);
178 
179 static int
180 ng_patch_constructor(node_p node)
181 {
182 	priv_p privdata;
183 
184 	privdata = malloc(sizeof(*privdata), M_NETGRAPH, M_WAITOK | M_ZERO);
185 	privdata->dlt = DLT_RAW;
186 
187 	NG_NODE_SET_PRIVATE(node, privdata);
188 
189 	return (0);
190 }
191 
192 static int
193 ng_patch_newhook(node_p node, hook_p hook, const char *name)
194 {
195 	const priv_p privp = NG_NODE_PRIVATE(node);
196 
197 	if (strncmp(name, NG_PATCH_HOOK_IN, strlen(NG_PATCH_HOOK_IN)) == 0) {
198 		privp->in = hook;
199 	} else if (strncmp(name, NG_PATCH_HOOK_OUT,
200 	    strlen(NG_PATCH_HOOK_OUT)) == 0) {
201 		privp->out = hook;
202 	} else
203 		return (EINVAL);
204 
205 	return (0);
206 }
207 
208 static int
209 ng_patch_rcvmsg(node_p node, item_p item, hook_p lasthook)
210 {
211 	const priv_p privp = NG_NODE_PRIVATE(node);
212 	struct ng_patch_config *conf, *newconf;
213 	struct ng_mesg *msg;
214 	struct ng_mesg *resp = NULL;
215 	int i, error = 0;
216 
217 	NGI_GET_MSG(item, msg);
218 
219 	if  (msg->header.typecookie != NGM_PATCH_COOKIE)
220 		ERROUT(EINVAL);
221 
222 	switch (msg->header.cmd)
223 	{
224 		case NGM_PATCH_GETCONFIG:
225 			if (privp->conf == NULL)
226 				ERROUT(0);
227 
228 			NG_MKRESPONSE(resp, msg,
229 			    NG_PATCH_CONF_SIZE(privp->conf->count), M_WAITOK);
230 
231 			if (resp == NULL)
232 				ERROUT(ENOMEM);
233 
234 			bcopy(privp->conf, resp->data,
235 			    NG_PATCH_CONF_SIZE(privp->conf->count));
236 
237 			conf = (struct ng_patch_config *) resp->data;
238 
239 			for (i = 0; i < conf->count; i++) {
240 				switch (conf->ops[i].length)
241 				{
242 					case 1:
243 						conf->ops[i].val.v8 = conf->ops[i].val.v1;
244 						break;
245 					case 2:
246 						conf->ops[i].val.v8 = conf->ops[i].val.v2;
247 						break;
248 					case 4:
249 						conf->ops[i].val.v8 = conf->ops[i].val.v4;
250 						break;
251 					case 8:
252 						break;
253 				}
254 			}
255 
256 			break;
257 
258 		case NGM_PATCH_SETCONFIG:
259 			conf = (struct ng_patch_config *) msg->data;
260 
261 			if (msg->header.arglen < sizeof(struct ng_patch_config) ||
262 			    msg->header.arglen < NG_PATCH_CONF_SIZE(conf->count))
263 				ERROUT(EINVAL);
264 
265 			for (i = 0; i < conf->count; i++) {
266 				switch (conf->ops[i].length)
267 				{
268 					case 1:
269 						conf->ops[i].val.v1 = (uint8_t) conf->ops[i].val.v8;
270 						break;
271 					case 2:
272 						conf->ops[i].val.v2 = (uint16_t) conf->ops[i].val.v8;
273 						break;
274 					case 4:
275 						conf->ops[i].val.v4 = (uint32_t) conf->ops[i].val.v8;
276 						break;
277 					case 8:
278 						break;
279 					default:
280 						ERROUT(EINVAL);
281 				}
282 			}
283 
284 			conf->csum_flags &= NG_PATCH_CSUM_IPV4|NG_PATCH_CSUM_IPV6;
285 			conf->relative_offset = !!conf->relative_offset;
286 
287 			newconf = malloc(NG_PATCH_CONF_SIZE(conf->count), M_NETGRAPH, M_WAITOK | M_ZERO);
288 
289 			bcopy(conf, newconf, NG_PATCH_CONF_SIZE(conf->count));
290 
291 			if (privp->conf)
292 				free(privp->conf, M_NETGRAPH);
293 
294 			privp->conf = newconf;
295 
296 			break;
297 
298 		case NGM_PATCH_GET_STATS:
299 		case NGM_PATCH_CLR_STATS:
300 		case NGM_PATCH_GETCLR_STATS:
301 			if (msg->header.cmd != NGM_PATCH_CLR_STATS) {
302 				NG_MKRESPONSE(resp, msg, sizeof(struct ng_patch_stats), M_WAITOK);
303 
304 				if (resp == NULL)
305 					ERROUT(ENOMEM);
306 
307 				bcopy(&(privp->stats), resp->data, sizeof(struct ng_patch_stats));
308 			}
309 
310 			if (msg->header.cmd != NGM_PATCH_GET_STATS)
311 				bzero(&(privp->stats), sizeof(struct ng_patch_stats));
312 
313 			break;
314 
315 		case NGM_PATCH_GETDLT:
316 			NG_MKRESPONSE(resp, msg, sizeof(uint8_t), M_WAITOK);
317 
318 			if (resp == NULL)
319 				ERROUT(ENOMEM);
320 
321 			*((uint8_t *) resp->data) = privp->dlt;
322 
323 			break;
324 
325 		case NGM_PATCH_SETDLT:
326 			if (msg->header.arglen != sizeof(uint8_t))
327 				ERROUT(EINVAL);
328 
329 			switch (*(uint8_t *) msg->data)
330 			{
331 				case DLT_EN10MB:
332 				case DLT_RAW:
333 					privp->dlt = *(uint8_t *) msg->data;
334 					break;
335 
336 				default:
337 					ERROUT(EINVAL);
338 			}
339 
340 			break;
341 
342 		default:
343 			ERROUT(EINVAL);
344 	}
345 
346 done:
347 	NG_RESPOND_MSG(error, node, item, resp);
348 	NG_FREE_MSG(msg);
349 
350 	return (error);
351 }
352 
353 static void
354 do_patch(priv_p privp, struct mbuf *m, int global_offset)
355 {
356 	int i, offset, patched = 0;
357 	union ng_patch_op_val val;
358 
359 	for (i = 0; i < privp->conf->count; i++) {
360 		offset = global_offset + privp->conf->ops[i].offset;
361 
362 		if (offset + privp->conf->ops[i].length > m->m_pkthdr.len)
363 			continue;
364 
365 		/* for "=" operation we don't need to copy data from mbuf */
366 		if (privp->conf->ops[i].mode != NG_PATCH_MODE_SET)
367 			m_copydata(m, offset, privp->conf->ops[i].length, (caddr_t) &val);
368 
369 		switch (privp->conf->ops[i].length)
370 		{
371 			case 1:
372 				switch (privp->conf->ops[i].mode)
373 				{
374 					case NG_PATCH_MODE_SET:
375 						val.v1 = privp->conf->ops[i].val.v1;
376 						break;
377 					case NG_PATCH_MODE_ADD:
378 						val.v1 += privp->conf->ops[i].val.v1;
379 						break;
380 					case NG_PATCH_MODE_SUB:
381 						val.v1 -= privp->conf->ops[i].val.v1;
382 						break;
383 					case NG_PATCH_MODE_MUL:
384 						val.v1 *= privp->conf->ops[i].val.v1;
385 						break;
386 					case NG_PATCH_MODE_DIV:
387 						val.v1 /= privp->conf->ops[i].val.v1;
388 						break;
389 					case NG_PATCH_MODE_NEG:
390 						*((int8_t *) &val) = - *((int8_t *) &val);
391 						break;
392 					case NG_PATCH_MODE_AND:
393 						val.v1 &= privp->conf->ops[i].val.v1;
394 						break;
395 					case NG_PATCH_MODE_OR:
396 						val.v1 |= privp->conf->ops[i].val.v1;
397 						break;
398 					case NG_PATCH_MODE_XOR:
399 						val.v1 ^= privp->conf->ops[i].val.v1;
400 						break;
401 					case NG_PATCH_MODE_SHL:
402 						val.v1 <<= privp->conf->ops[i].val.v1;
403 						break;
404 					case NG_PATCH_MODE_SHR:
405 						val.v1 >>= privp->conf->ops[i].val.v1;
406 						break;
407 				}
408 				break;
409 
410 			case 2:
411 				val.v2 = ntohs(val.v2);
412 
413 				switch (privp->conf->ops[i].mode)
414 				{
415 					case NG_PATCH_MODE_SET:
416 						val.v2 = privp->conf->ops[i].val.v2;
417 						break;
418 					case NG_PATCH_MODE_ADD:
419 						val.v2 += privp->conf->ops[i].val.v2;
420 						break;
421 					case NG_PATCH_MODE_SUB:
422 						val.v2 -= privp->conf->ops[i].val.v2;
423 						break;
424 					case NG_PATCH_MODE_MUL:
425 						val.v2 *= privp->conf->ops[i].val.v2;
426 						break;
427 					case NG_PATCH_MODE_DIV:
428 						val.v2 /= privp->conf->ops[i].val.v2;
429 						break;
430 					case NG_PATCH_MODE_NEG:
431 						*((int16_t *) &val) = - *((int16_t *) &val);
432 						break;
433 					case NG_PATCH_MODE_AND:
434 						val.v2 &= privp->conf->ops[i].val.v2;
435 						break;
436 					case NG_PATCH_MODE_OR:
437 						val.v2 |= privp->conf->ops[i].val.v2;
438 						break;
439 					case NG_PATCH_MODE_XOR:
440 						val.v2 ^= privp->conf->ops[i].val.v2;
441 						break;
442 					case NG_PATCH_MODE_SHL:
443 						val.v2 <<= privp->conf->ops[i].val.v2;
444 						break;
445 					case NG_PATCH_MODE_SHR:
446 						val.v2 >>= privp->conf->ops[i].val.v2;
447 						break;
448 				}
449 
450 				val.v2 = htons(val.v2);
451 
452 				break;
453 
454 			case 4:
455 				val.v4 = ntohl(val.v4);
456 
457 				switch (privp->conf->ops[i].mode)
458 				{
459 					case NG_PATCH_MODE_SET:
460 						val.v4 = privp->conf->ops[i].val.v4;
461 						break;
462 					case NG_PATCH_MODE_ADD:
463 						val.v4 += privp->conf->ops[i].val.v4;
464 						break;
465 					case NG_PATCH_MODE_SUB:
466 						val.v4 -= privp->conf->ops[i].val.v4;
467 						break;
468 					case NG_PATCH_MODE_MUL:
469 						val.v4 *= privp->conf->ops[i].val.v4;
470 						break;
471 					case NG_PATCH_MODE_DIV:
472 						val.v4 /= privp->conf->ops[i].val.v4;
473 						break;
474 					case NG_PATCH_MODE_NEG:
475 						*((int32_t *) &val) = - *((int32_t *) &val);
476 						break;
477 					case NG_PATCH_MODE_AND:
478 						val.v4 &= privp->conf->ops[i].val.v4;
479 						break;
480 					case NG_PATCH_MODE_OR:
481 						val.v4 |= privp->conf->ops[i].val.v4;
482 						break;
483 					case NG_PATCH_MODE_XOR:
484 						val.v4 ^= privp->conf->ops[i].val.v4;
485 						break;
486 					case NG_PATCH_MODE_SHL:
487 						val.v4 <<= privp->conf->ops[i].val.v4;
488 						break;
489 					case NG_PATCH_MODE_SHR:
490 						val.v4 >>= privp->conf->ops[i].val.v4;
491 						break;
492 				}
493 
494 				val.v4 = htonl(val.v4);
495 
496 				break;
497 
498 			case 8:
499 				val.v8 = be64toh(val.v8);
500 
501 				switch (privp->conf->ops[i].mode)
502 				{
503 					case NG_PATCH_MODE_SET:
504 						val.v8 = privp->conf->ops[i].val.v8;
505 						break;
506 					case NG_PATCH_MODE_ADD:
507 						val.v8 += privp->conf->ops[i].val.v8;
508 						break;
509 					case NG_PATCH_MODE_SUB:
510 						val.v8 -= privp->conf->ops[i].val.v8;
511 						break;
512 					case NG_PATCH_MODE_MUL:
513 						val.v8 *= privp->conf->ops[i].val.v8;
514 						break;
515 					case NG_PATCH_MODE_DIV:
516 						val.v8 /= privp->conf->ops[i].val.v8;
517 						break;
518 					case NG_PATCH_MODE_NEG:
519 						*((int64_t *) &val) = - *((int64_t *) &val);
520 						break;
521 					case NG_PATCH_MODE_AND:
522 						val.v8 &= privp->conf->ops[i].val.v8;
523 						break;
524 					case NG_PATCH_MODE_OR:
525 						val.v8 |= privp->conf->ops[i].val.v8;
526 						break;
527 					case NG_PATCH_MODE_XOR:
528 						val.v8 ^= privp->conf->ops[i].val.v8;
529 						break;
530 					case NG_PATCH_MODE_SHL:
531 						val.v8 <<= privp->conf->ops[i].val.v8;
532 						break;
533 					case NG_PATCH_MODE_SHR:
534 						val.v8 >>= privp->conf->ops[i].val.v8;
535 						break;
536 				}
537 
538 				val.v8 = htobe64(val.v8);
539 
540 				break;
541 		}
542 
543 		m_copyback(m, offset, privp->conf->ops[i].length, (caddr_t) &val);
544 		patched = 1;
545 	}
546 
547 	if (patched)
548 		privp->stats.patched++;
549 }
550 
551 static int
552 ng_patch_rcvdata(hook_p hook, item_p item)
553 {
554 	const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
555 	struct mbuf *m;
556 	hook_p out;
557 	int pullup_len = 0;
558 	int error = 0;
559 
560 	priv->stats.received++;
561 
562 	NGI_GET_M(item, m);
563 
564 #define	PULLUP_CHECK(mbuf, length) do {					\
565 	pullup_len += length;						\
566 	if (((mbuf)->m_pkthdr.len < pullup_len) ||			\
567 	    (pullup_len > MHLEN)) {					\
568 		error = EINVAL;						\
569 		goto bypass;						\
570 	}								\
571 	if ((mbuf)->m_len < pullup_len &&				\
572 	    (((mbuf) = m_pullup((mbuf), pullup_len)) == NULL)) {	\
573 		error = ENOBUFS;					\
574 		goto drop;						\
575 	}								\
576 } while (0)
577 
578 	if (priv->conf && hook == priv->in &&
579 	    m && (m->m_flags & M_PKTHDR)) {
580 		m = m_unshare(m, M_NOWAIT);
581 
582 		if (m == NULL)
583 			ERROUT(ENOMEM);
584 
585 		if (priv->conf->relative_offset) {
586 			struct ether_header *eh;
587 			struct ng_patch_vlan_header *vh;
588 			uint16_t etype;
589 
590 			switch (priv->dlt)
591 			{
592 				case DLT_EN10MB:
593 					PULLUP_CHECK(m, sizeof(struct ether_header));
594 					eh = mtod(m, struct ether_header *);
595 					etype = ntohs(eh->ether_type);
596 
597 					for (;;) {	/* QinQ support */
598 						switch (etype)
599 						{
600 							case 0x8100:
601 							case 0x88A8:
602 							case 0x9100:
603 								PULLUP_CHECK(m, sizeof(struct ng_patch_vlan_header));
604 								vh = (struct ng_patch_vlan_header *) mtodo(m,
605 								    pullup_len - sizeof(struct ng_patch_vlan_header));
606 								etype = ntohs(vh->etype);
607 								break;
608 
609 							default:
610 								goto loopend;
611 						}
612 					}
613 loopend:
614 					break;
615 
616 				case DLT_RAW:
617 					break;
618 
619 				default:
620 					ERROUT(EINVAL);
621 			}
622 		}
623 
624 		do_patch(priv, m, pullup_len);
625 
626 		m->m_pkthdr.csum_flags |= priv->conf->csum_flags;
627 	}
628 
629 #undef	PULLUP_CHECK
630 
631 bypass:
632 	out = NULL;
633 
634 	if (hook == priv->in) {
635 		/* return frames on 'in' hook if 'out' not connected */
636 		out = priv->out ? priv->out : priv->in;
637 	} else if (hook == priv->out && priv->in) {
638 		/* pass frames on 'out' hook if 'in' connected */
639 		out = priv->in;
640 	}
641 
642 	if (out == NULL)
643 		ERROUT(0);
644 
645 	NG_FWD_NEW_DATA(error, item, out, m);
646 
647 	return (error);
648 
649 done:
650 drop:
651 	NG_FREE_ITEM(item);
652 	NG_FREE_M(m);
653 
654 	priv->stats.dropped++;
655 
656 	return (error);
657 }
658 
659 static int
660 ng_patch_shutdown(node_p node)
661 {
662 	const priv_p privdata = NG_NODE_PRIVATE(node);
663 
664 	NG_NODE_SET_PRIVATE(node, NULL);
665 	NG_NODE_UNREF(node);
666 
667 	if (privdata->conf != NULL)
668 		free(privdata->conf, M_NETGRAPH);
669 
670 	free(privdata, M_NETGRAPH);
671 
672 	return (0);
673 }
674 
675 static int
676 ng_patch_disconnect(hook_p hook)
677 {
678 	priv_p priv;
679 
680 	priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
681 
682 	if (hook == priv->in) {
683 		priv->in = NULL;
684 	}
685 
686 	if (hook == priv->out) {
687 		priv->out = NULL;
688 	}
689 
690 	if (NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0 &&
691 	    NG_NODE_IS_VALID(NG_HOOK_NODE(hook))) /* already shutting down? */
692 		ng_rmnode_self(NG_HOOK_NODE(hook));
693 
694 	return (0);
695 }
696