xref: /freebsd/sys/netinet/ip_carp.c (revision e28a4053)
1 /*
2  * Copyright (c) 2002 Michael Shalayeff. All rights reserved.
3  * Copyright (c) 2003 Ryan McBride. All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17  * IN NO EVENT SHALL THE AUTHOR OR HIS RELATIVES BE LIABLE FOR ANY DIRECT,
18  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
20  * SERVICES; LOSS OF MIND, USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
22  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
23  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
24  * THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include "opt_bpf.h"
31 #include "opt_inet.h"
32 #include "opt_inet6.h"
33 
34 #include <sys/types.h>
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/conf.h>
38 #include <sys/kernel.h>
39 #include <sys/limits.h>
40 #include <sys/malloc.h>
41 #include <sys/mbuf.h>
42 #include <sys/module.h>
43 #include <sys/time.h>
44 #include <sys/priv.h>
45 #include <sys/proc.h>
46 #include <sys/protosw.h>
47 #include <sys/sysctl.h>
48 #include <sys/syslog.h>
49 #include <sys/signalvar.h>
50 #include <sys/filio.h>
51 #include <sys/sockio.h>
52 
53 #include <sys/socket.h>
54 #include <sys/vnode.h>
55 
56 #include <machine/stdarg.h>
57 
58 #include <net/bpf.h>
59 #include <net/ethernet.h>
60 #include <net/fddi.h>
61 #include <net/iso88025.h>
62 #include <net/if.h>
63 #include <net/if_clone.h>
64 #include <net/if_dl.h>
65 #include <net/if_types.h>
66 #include <net/route.h>
67 #include <net/vnet.h>
68 
69 #ifdef INET
70 #include <netinet/in.h>
71 #include <netinet/in_var.h>
72 #include <netinet/in_systm.h>
73 #include <netinet/ip.h>
74 #include <netinet/ip_var.h>
75 #include <netinet/if_ether.h>
76 #include <machine/in_cksum.h>
77 #endif
78 
79 #ifdef INET6
80 #include <netinet/icmp6.h>
81 #include <netinet/ip6.h>
82 #include <netinet6/ip6protosw.h>
83 #include <netinet6/ip6_var.h>
84 #include <netinet6/scope6_var.h>
85 #include <netinet6/nd6.h>
86 #endif
87 
88 #include <crypto/sha1.h>
89 #include <netinet/ip_carp.h>
90 
91 #define	CARP_IFNAME	"carp"
92 static MALLOC_DEFINE(M_CARP, "CARP", "CARP interfaces");
93 SYSCTL_DECL(_net_inet_carp);
94 
95 struct carp_softc {
96 	struct ifnet	 	*sc_ifp;	/* Interface clue */
97 	struct ifnet		*sc_carpdev;	/* Pointer to parent interface */
98 	struct in_ifaddr 	*sc_ia;		/* primary iface address */
99 	struct ip_moptions 	 sc_imo;
100 #ifdef INET6
101 	struct in6_ifaddr 	*sc_ia6;	/* primary iface address v6 */
102 	struct ip6_moptions 	 sc_im6o;
103 #endif /* INET6 */
104 	TAILQ_ENTRY(carp_softc)	 sc_list;
105 
106 	enum { INIT = 0, BACKUP, MASTER }	sc_state;
107 
108 	int			 sc_flags_backup;
109 	int			 sc_suppress;
110 
111 	int			 sc_sendad_errors;
112 #define	CARP_SENDAD_MAX_ERRORS	3
113 	int			 sc_sendad_success;
114 #define	CARP_SENDAD_MIN_SUCCESS 3
115 
116 	int			 sc_vhid;
117 	int			 sc_advskew;
118 	int			 sc_naddrs;
119 	int			 sc_naddrs6;
120 	int			 sc_advbase;	/* seconds */
121 	int			 sc_init_counter;
122 	u_int64_t		 sc_counter;
123 
124 	/* authentication */
125 #define CARP_HMAC_PAD	64
126 	unsigned char sc_key[CARP_KEY_LEN];
127 	unsigned char sc_pad[CARP_HMAC_PAD];
128 	SHA1_CTX sc_sha1;
129 
130 	struct callout		 sc_ad_tmo;	/* advertisement timeout */
131 	struct callout		 sc_md_tmo;	/* master down timeout */
132 	struct callout 		 sc_md6_tmo;	/* master down timeout */
133 
134 	LIST_ENTRY(carp_softc)	 sc_next;	/* Interface clue */
135 };
136 #define	SC2IFP(sc)	((sc)->sc_ifp)
137 
138 int carp_suppress_preempt = 0;
139 int carp_opts[CARPCTL_MAXID] = { 0, 1, 0, 1, 0, 0 };	/* XXX for now */
140 SYSCTL_NODE(_net_inet, IPPROTO_CARP,	carp,	CTLFLAG_RW, 0,	"CARP");
141 SYSCTL_INT(_net_inet_carp, CARPCTL_ALLOW, allow, CTLFLAG_RW,
142     &carp_opts[CARPCTL_ALLOW], 0, "Accept incoming CARP packets");
143 SYSCTL_INT(_net_inet_carp, CARPCTL_PREEMPT, preempt, CTLFLAG_RW,
144     &carp_opts[CARPCTL_PREEMPT], 0, "high-priority backup preemption mode");
145 SYSCTL_INT(_net_inet_carp, CARPCTL_LOG, log, CTLFLAG_RW,
146     &carp_opts[CARPCTL_LOG], 0, "log bad carp packets");
147 SYSCTL_INT(_net_inet_carp, CARPCTL_ARPBALANCE, arpbalance, CTLFLAG_RW,
148     &carp_opts[CARPCTL_ARPBALANCE], 0, "balance arp responses");
149 SYSCTL_INT(_net_inet_carp, OID_AUTO, suppress_preempt, CTLFLAG_RD,
150     &carp_suppress_preempt, 0, "Preemption is suppressed");
151 
152 struct carpstats carpstats;
153 SYSCTL_STRUCT(_net_inet_carp, CARPCTL_STATS, stats, CTLFLAG_RW,
154     &carpstats, carpstats,
155     "CARP statistics (struct carpstats, netinet/ip_carp.h)");
156 
157 struct carp_if {
158 	TAILQ_HEAD(, carp_softc) vhif_vrs;
159 	int vhif_nvrs;
160 
161 	struct ifnet 	*vhif_ifp;
162 	struct mtx	 vhif_mtx;
163 };
164 
165 #define	CARP_INET	0
166 #define	CARP_INET6	1
167 static int proto_reg[] = {-1, -1};
168 
169 /* Get carp_if from softc. Valid after carp_set_addr{,6}. */
170 #define	SC2CIF(sc)		((struct carp_if *)(sc)->sc_carpdev->if_carp)
171 
172 /* lock per carp_if queue */
173 #define	CARP_LOCK_INIT(cif)	mtx_init(&(cif)->vhif_mtx, "carp_if", 	\
174 	NULL, MTX_DEF)
175 #define	CARP_LOCK_DESTROY(cif)	mtx_destroy(&(cif)->vhif_mtx)
176 #define	CARP_LOCK_ASSERT(cif)	mtx_assert(&(cif)->vhif_mtx, MA_OWNED)
177 #define	CARP_LOCK(cif)		mtx_lock(&(cif)->vhif_mtx)
178 #define	CARP_UNLOCK(cif)	mtx_unlock(&(cif)->vhif_mtx)
179 
180 #define	CARP_SCLOCK(sc)		mtx_lock(&SC2CIF(sc)->vhif_mtx)
181 #define	CARP_SCUNLOCK(sc)	mtx_unlock(&SC2CIF(sc)->vhif_mtx)
182 #define	CARP_SCLOCK_ASSERT(sc)	mtx_assert(&SC2CIF(sc)->vhif_mtx, MA_OWNED)
183 
184 #define	CARP_LOG(...)	do {				\
185 	if (carp_opts[CARPCTL_LOG] > 0)			\
186 		log(LOG_INFO, __VA_ARGS__);		\
187 } while (0)
188 
189 #define	CARP_DEBUG(...)	do {				\
190 	if (carp_opts[CARPCTL_LOG] > 1)			\
191 		log(LOG_DEBUG, __VA_ARGS__);		\
192 } while (0)
193 
194 static void	carp_hmac_prepare(struct carp_softc *);
195 static void	carp_hmac_generate(struct carp_softc *, u_int32_t *,
196 		    unsigned char *);
197 static int	carp_hmac_verify(struct carp_softc *, u_int32_t *,
198 		    unsigned char *);
199 static void	carp_setroute(struct carp_softc *, int);
200 static void	carp_input_c(struct mbuf *, struct carp_header *, sa_family_t);
201 static int 	carp_clone_create(struct if_clone *, int, caddr_t);
202 static void 	carp_clone_destroy(struct ifnet *);
203 static void	carpdetach(struct carp_softc *, int);
204 static int	carp_prepare_ad(struct mbuf *, struct carp_softc *,
205 		    struct carp_header *);
206 static void	carp_send_ad_all(void);
207 static void	carp_send_ad(void *);
208 static void	carp_send_ad_locked(struct carp_softc *);
209 static void	carp_send_arp(struct carp_softc *);
210 static void	carp_master_down(void *);
211 static void	carp_master_down_locked(struct carp_softc *);
212 static int	carp_ioctl(struct ifnet *, u_long, caddr_t);
213 static int	carp_looutput(struct ifnet *, struct mbuf *, struct sockaddr *,
214     		    struct route *);
215 static void	carp_start(struct ifnet *);
216 static void	carp_setrun(struct carp_softc *, sa_family_t);
217 static void	carp_set_state(struct carp_softc *, int);
218 static int	carp_addrcount(struct carp_if *, struct in_ifaddr *, int);
219 enum	{ CARP_COUNT_MASTER, CARP_COUNT_RUNNING };
220 
221 static void	carp_multicast_cleanup(struct carp_softc *);
222 static int	carp_set_addr(struct carp_softc *, struct sockaddr_in *);
223 static int	carp_del_addr(struct carp_softc *, struct sockaddr_in *);
224 static void	carp_carpdev_state_locked(struct carp_if *);
225 static void	carp_sc_state_locked(struct carp_softc *);
226 #ifdef INET6
227 static void	carp_send_na(struct carp_softc *);
228 static int	carp_set_addr6(struct carp_softc *, struct sockaddr_in6 *);
229 static int	carp_del_addr6(struct carp_softc *, struct sockaddr_in6 *);
230 static void	carp_multicast6_cleanup(struct carp_softc *);
231 #endif
232 
233 static LIST_HEAD(, carp_softc) carpif_list;
234 static struct mtx carp_mtx;
235 IFC_SIMPLE_DECLARE(carp, 0);
236 
237 static eventhandler_tag if_detach_event_tag;
238 
239 static __inline u_int16_t
240 carp_cksum(struct mbuf *m, int len)
241 {
242 	return (in_cksum(m, len));
243 }
244 
245 static void
246 carp_hmac_prepare(struct carp_softc *sc)
247 {
248 	u_int8_t version = CARP_VERSION, type = CARP_ADVERTISEMENT;
249 	u_int8_t vhid = sc->sc_vhid & 0xff;
250 	struct ifaddr *ifa;
251 	int i, found;
252 #ifdef INET
253 	struct in_addr last, cur, in;
254 #endif
255 #ifdef INET6
256 	struct in6_addr last6, cur6, in6;
257 #endif
258 
259 	if (sc->sc_carpdev)
260 		CARP_SCLOCK(sc);
261 
262 	/* XXX: possible race here */
263 
264 	/* compute ipad from key */
265 	bzero(sc->sc_pad, sizeof(sc->sc_pad));
266 	bcopy(sc->sc_key, sc->sc_pad, sizeof(sc->sc_key));
267 	for (i = 0; i < sizeof(sc->sc_pad); i++)
268 		sc->sc_pad[i] ^= 0x36;
269 
270 	/* precompute first part of inner hash */
271 	SHA1Init(&sc->sc_sha1);
272 	SHA1Update(&sc->sc_sha1, sc->sc_pad, sizeof(sc->sc_pad));
273 	SHA1Update(&sc->sc_sha1, (void *)&version, sizeof(version));
274 	SHA1Update(&sc->sc_sha1, (void *)&type, sizeof(type));
275 	SHA1Update(&sc->sc_sha1, (void *)&vhid, sizeof(vhid));
276 #ifdef INET
277 	cur.s_addr = 0;
278 	do {
279 		found = 0;
280 		last = cur;
281 		cur.s_addr = 0xffffffff;
282 		IF_ADDR_LOCK(SC2IFP(sc));
283 		TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
284 			in.s_addr = ifatoia(ifa)->ia_addr.sin_addr.s_addr;
285 			if (ifa->ifa_addr->sa_family == AF_INET &&
286 			    ntohl(in.s_addr) > ntohl(last.s_addr) &&
287 			    ntohl(in.s_addr) < ntohl(cur.s_addr)) {
288 				cur.s_addr = in.s_addr;
289 				found++;
290 			}
291 		}
292 		IF_ADDR_UNLOCK(SC2IFP(sc));
293 		if (found)
294 			SHA1Update(&sc->sc_sha1, (void *)&cur, sizeof(cur));
295 	} while (found);
296 #endif /* INET */
297 #ifdef INET6
298 	memset(&cur6, 0, sizeof(cur6));
299 	do {
300 		found = 0;
301 		last6 = cur6;
302 		memset(&cur6, 0xff, sizeof(cur6));
303 		IF_ADDR_LOCK(SC2IFP(sc));
304 		TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
305 			in6 = ifatoia6(ifa)->ia_addr.sin6_addr;
306 			if (IN6_IS_SCOPE_EMBED(&in6))
307 				in6.s6_addr16[1] = 0;
308 			if (ifa->ifa_addr->sa_family == AF_INET6 &&
309 			    memcmp(&in6, &last6, sizeof(in6)) > 0 &&
310 			    memcmp(&in6, &cur6, sizeof(in6)) < 0) {
311 				cur6 = in6;
312 				found++;
313 			}
314 		}
315 		IF_ADDR_UNLOCK(SC2IFP(sc));
316 		if (found)
317 			SHA1Update(&sc->sc_sha1, (void *)&cur6, sizeof(cur6));
318 	} while (found);
319 #endif /* INET6 */
320 
321 	/* convert ipad to opad */
322 	for (i = 0; i < sizeof(sc->sc_pad); i++)
323 		sc->sc_pad[i] ^= 0x36 ^ 0x5c;
324 
325 	if (sc->sc_carpdev)
326 		CARP_SCUNLOCK(sc);
327 }
328 
329 static void
330 carp_hmac_generate(struct carp_softc *sc, u_int32_t counter[2],
331     unsigned char md[20])
332 {
333 	SHA1_CTX sha1ctx;
334 
335 	/* fetch first half of inner hash */
336 	bcopy(&sc->sc_sha1, &sha1ctx, sizeof(sha1ctx));
337 
338 	SHA1Update(&sha1ctx, (void *)counter, sizeof(sc->sc_counter));
339 	SHA1Final(md, &sha1ctx);
340 
341 	/* outer hash */
342 	SHA1Init(&sha1ctx);
343 	SHA1Update(&sha1ctx, sc->sc_pad, sizeof(sc->sc_pad));
344 	SHA1Update(&sha1ctx, md, 20);
345 	SHA1Final(md, &sha1ctx);
346 }
347 
348 static int
349 carp_hmac_verify(struct carp_softc *sc, u_int32_t counter[2],
350     unsigned char md[20])
351 {
352 	unsigned char md2[20];
353 
354 	CARP_SCLOCK_ASSERT(sc);
355 
356 	carp_hmac_generate(sc, counter, md2);
357 
358 	return (bcmp(md, md2, sizeof(md2)));
359 }
360 
361 static void
362 carp_setroute(struct carp_softc *sc, int cmd)
363 {
364 	struct ifaddr *ifa;
365 	int s;
366 
367 	if (sc->sc_carpdev)
368 		CARP_SCLOCK_ASSERT(sc);
369 
370 	s = splnet();
371 	TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
372 		if (ifa->ifa_addr->sa_family == AF_INET &&
373 		    sc->sc_carpdev != NULL) {
374 			int count = carp_addrcount(
375 			    (struct carp_if *)sc->sc_carpdev->if_carp,
376 			    ifatoia(ifa), CARP_COUNT_MASTER);
377 
378 			if ((cmd == RTM_ADD && count == 1) ||
379 			    (cmd == RTM_DELETE && count == 0))
380 				rtinit(ifa, cmd, RTF_UP | RTF_HOST);
381 		}
382 	}
383 	splx(s);
384 }
385 
386 static int
387 carp_clone_create(struct if_clone *ifc, int unit, caddr_t params)
388 {
389 
390 	struct carp_softc *sc;
391 	struct ifnet *ifp;
392 
393 	sc = malloc(sizeof(*sc), M_CARP, M_WAITOK|M_ZERO);
394 	ifp = SC2IFP(sc) = if_alloc(IFT_ETHER);
395 	if (ifp == NULL) {
396 		free(sc, M_CARP);
397 		return (ENOSPC);
398 	}
399 
400 	sc->sc_flags_backup = 0;
401 	sc->sc_suppress = 0;
402 	sc->sc_advbase = CARP_DFLTINTV;
403 	sc->sc_vhid = -1;	/* required setting */
404 	sc->sc_advskew = 0;
405 	sc->sc_init_counter = 1;
406 	sc->sc_naddrs = sc->sc_naddrs6 = 0; /* M_ZERO? */
407 	sc->sc_imo.imo_membership = (struct in_multi **)malloc(
408 	    (sizeof(struct in_multi *) * IP_MIN_MEMBERSHIPS), M_CARP,
409 	    M_WAITOK);
410 	sc->sc_imo.imo_mfilters = NULL;
411 	sc->sc_imo.imo_max_memberships = IP_MIN_MEMBERSHIPS;
412 	sc->sc_imo.imo_multicast_vif = -1;
413 #ifdef INET6
414 	sc->sc_im6o.im6o_membership = (struct in6_multi **)malloc(
415 	    (sizeof(struct in6_multi *) * IPV6_MIN_MEMBERSHIPS), M_CARP,
416 	    M_WAITOK);
417 	sc->sc_im6o.im6o_mfilters = NULL;
418 	sc->sc_im6o.im6o_max_memberships = IPV6_MIN_MEMBERSHIPS;
419 	sc->sc_im6o.im6o_multicast_hlim = CARP_DFLTTL;
420 #endif
421 
422 	callout_init(&sc->sc_ad_tmo, CALLOUT_MPSAFE);
423 	callout_init(&sc->sc_md_tmo, CALLOUT_MPSAFE);
424 	callout_init(&sc->sc_md6_tmo, CALLOUT_MPSAFE);
425 
426 	ifp->if_softc = sc;
427 	if_initname(ifp, CARP_IFNAME, unit);
428 	ifp->if_mtu = ETHERMTU;
429 	ifp->if_flags = IFF_LOOPBACK;
430 	ifp->if_ioctl = carp_ioctl;
431 	ifp->if_output = carp_looutput;
432 	ifp->if_start = carp_start;
433 	ifp->if_type = IFT_CARP;
434 	ifp->if_snd.ifq_maxlen = ifqmaxlen;
435 	ifp->if_hdrlen = 0;
436 	if_attach(ifp);
437 	bpfattach(SC2IFP(sc), DLT_NULL, sizeof(u_int32_t));
438 	mtx_lock(&carp_mtx);
439 	LIST_INSERT_HEAD(&carpif_list, sc, sc_next);
440 	mtx_unlock(&carp_mtx);
441 	return (0);
442 }
443 
444 static void
445 carp_clone_destroy(struct ifnet *ifp)
446 {
447 	struct carp_softc *sc = ifp->if_softc;
448 
449 	if (sc->sc_carpdev)
450 		CARP_SCLOCK(sc);
451 	carpdetach(sc, 1);	/* Returns unlocked. */
452 
453 	mtx_lock(&carp_mtx);
454 	LIST_REMOVE(sc, sc_next);
455 	mtx_unlock(&carp_mtx);
456 	bpfdetach(ifp);
457 	if_detach(ifp);
458 	if_free_type(ifp, IFT_ETHER);
459 	free(sc->sc_imo.imo_membership, M_CARP);
460 #ifdef INET6
461 	free(sc->sc_im6o.im6o_membership, M_CARP);
462 #endif
463 	free(sc, M_CARP);
464 }
465 
466 /*
467  * This function can be called on CARP interface destroy path,
468  * and in case of the removal of the underlying interface as
469  * well. We differentiate these two cases. In the latter case
470  * we do not cleanup our multicast memberships, since they
471  * are already freed. Also, in the latter case we do not
472  * release the lock on return, because the function will be
473  * called once more, for another CARP instance on the same
474  * interface.
475  */
476 static void
477 carpdetach(struct carp_softc *sc, int unlock)
478 {
479 	struct carp_if *cif;
480 
481 	callout_stop(&sc->sc_ad_tmo);
482 	callout_stop(&sc->sc_md_tmo);
483 	callout_stop(&sc->sc_md6_tmo);
484 
485 	if (sc->sc_suppress)
486 		carp_suppress_preempt--;
487 	sc->sc_suppress = 0;
488 
489 	if (sc->sc_sendad_errors >= CARP_SENDAD_MAX_ERRORS)
490 		carp_suppress_preempt--;
491 	sc->sc_sendad_errors = 0;
492 
493 	carp_set_state(sc, INIT);
494 	SC2IFP(sc)->if_flags &= ~IFF_UP;
495 	carp_setrun(sc, 0);
496 	if (unlock)
497 		carp_multicast_cleanup(sc);
498 #ifdef INET6
499 	carp_multicast6_cleanup(sc);
500 #endif
501 
502 	if (sc->sc_carpdev != NULL) {
503 		cif = (struct carp_if *)sc->sc_carpdev->if_carp;
504 		CARP_LOCK_ASSERT(cif);
505 		TAILQ_REMOVE(&cif->vhif_vrs, sc, sc_list);
506 		if (!--cif->vhif_nvrs) {
507 			ifpromisc(sc->sc_carpdev, 0);
508 			sc->sc_carpdev->if_carp = NULL;
509 			CARP_LOCK_DESTROY(cif);
510 			free(cif, M_CARP);
511 		} else if (unlock)
512 			CARP_UNLOCK(cif);
513 		sc->sc_carpdev = NULL;
514 	}
515 }
516 
517 /* Detach an interface from the carp. */
518 static void
519 carp_ifdetach(void *arg __unused, struct ifnet *ifp)
520 {
521 	struct carp_if *cif = (struct carp_if *)ifp->if_carp;
522 	struct carp_softc *sc, *nextsc;
523 
524 	if (cif == NULL)
525 		return;
526 
527 	/*
528 	 * XXX: At the end of for() cycle the lock will be destroyed.
529 	 */
530 	CARP_LOCK(cif);
531 	for (sc = TAILQ_FIRST(&cif->vhif_vrs); sc; sc = nextsc) {
532 		nextsc = TAILQ_NEXT(sc, sc_list);
533 		carpdetach(sc, 0);
534 	}
535 }
536 
537 /*
538  * process input packet.
539  * we have rearranged checks order compared to the rfc,
540  * but it seems more efficient this way or not possible otherwise.
541  */
542 void
543 carp_input(struct mbuf *m, int hlen)
544 {
545 	struct ip *ip = mtod(m, struct ip *);
546 	struct carp_header *ch;
547 	int iplen, len;
548 
549 	CARPSTATS_INC(carps_ipackets);
550 
551 	if (!carp_opts[CARPCTL_ALLOW]) {
552 		m_freem(m);
553 		return;
554 	}
555 
556 	/* check if received on a valid carp interface */
557 	if (m->m_pkthdr.rcvif->if_carp == NULL) {
558 		CARPSTATS_INC(carps_badif);
559 		CARP_DEBUG("carp_input: packet received on non-carp "
560 		    "interface: %s\n",
561 		    m->m_pkthdr.rcvif->if_xname);
562 		m_freem(m);
563 		return;
564 	}
565 
566 	/* verify that the IP TTL is 255.  */
567 	if (ip->ip_ttl != CARP_DFLTTL) {
568 		CARPSTATS_INC(carps_badttl);
569 		CARP_DEBUG("carp_input: received ttl %d != 255 on %s\n",
570 		    ip->ip_ttl,
571 		    m->m_pkthdr.rcvif->if_xname);
572 		m_freem(m);
573 		return;
574 	}
575 
576 	iplen = ip->ip_hl << 2;
577 
578 	if (m->m_pkthdr.len < iplen + sizeof(*ch)) {
579 		CARPSTATS_INC(carps_badlen);
580 		CARP_DEBUG("carp_input: received len %zd < "
581 		    "sizeof(struct carp_header) on %s\n",
582 		    m->m_len - sizeof(struct ip),
583 		    m->m_pkthdr.rcvif->if_xname);
584 		m_freem(m);
585 		return;
586 	}
587 
588 	if (iplen + sizeof(*ch) < m->m_len) {
589 		if ((m = m_pullup(m, iplen + sizeof(*ch))) == NULL) {
590 			CARPSTATS_INC(carps_hdrops);
591 			CARP_DEBUG("carp_input: pullup failed\n");
592 			return;
593 		}
594 		ip = mtod(m, struct ip *);
595 	}
596 	ch = (struct carp_header *)((char *)ip + iplen);
597 
598 	/*
599 	 * verify that the received packet length is
600 	 * equal to the CARP header
601 	 */
602 	len = iplen + sizeof(*ch);
603 	if (len > m->m_pkthdr.len) {
604 		CARPSTATS_INC(carps_badlen);
605 		CARP_DEBUG("carp_input: packet too short %d on %s\n",
606 		    m->m_pkthdr.len,
607 		    m->m_pkthdr.rcvif->if_xname);
608 		m_freem(m);
609 		return;
610 	}
611 
612 	if ((m = m_pullup(m, len)) == NULL) {
613 		CARPSTATS_INC(carps_hdrops);
614 		return;
615 	}
616 	ip = mtod(m, struct ip *);
617 	ch = (struct carp_header *)((char *)ip + iplen);
618 
619 	/* verify the CARP checksum */
620 	m->m_data += iplen;
621 	if (carp_cksum(m, len - iplen)) {
622 		CARPSTATS_INC(carps_badsum);
623 		CARP_DEBUG("carp_input: checksum failed on %s\n",
624 		    m->m_pkthdr.rcvif->if_xname);
625 		m_freem(m);
626 		return;
627 	}
628 	m->m_data -= iplen;
629 
630 	carp_input_c(m, ch, AF_INET);
631 }
632 
633 #ifdef INET6
634 int
635 carp6_input(struct mbuf **mp, int *offp, int proto)
636 {
637 	struct mbuf *m = *mp;
638 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
639 	struct carp_header *ch;
640 	u_int len;
641 
642 	CARPSTATS_INC(carps_ipackets6);
643 
644 	if (!carp_opts[CARPCTL_ALLOW]) {
645 		m_freem(m);
646 		return (IPPROTO_DONE);
647 	}
648 
649 	/* check if received on a valid carp interface */
650 	if (m->m_pkthdr.rcvif->if_carp == NULL) {
651 		CARPSTATS_INC(carps_badif);
652 		CARP_DEBUG("carp6_input: packet received on non-carp "
653 		    "interface: %s\n",
654 		    m->m_pkthdr.rcvif->if_xname);
655 		m_freem(m);
656 		return (IPPROTO_DONE);
657 	}
658 
659 	/* verify that the IP TTL is 255 */
660 	if (ip6->ip6_hlim != CARP_DFLTTL) {
661 		CARPSTATS_INC(carps_badttl);
662 		CARP_DEBUG("carp6_input: received ttl %d != 255 on %s\n",
663 		    ip6->ip6_hlim,
664 		    m->m_pkthdr.rcvif->if_xname);
665 		m_freem(m);
666 		return (IPPROTO_DONE);
667 	}
668 
669 	/* verify that we have a complete carp packet */
670 	len = m->m_len;
671 	IP6_EXTHDR_GET(ch, struct carp_header *, m, *offp, sizeof(*ch));
672 	if (ch == NULL) {
673 		CARPSTATS_INC(carps_badlen);
674 		CARP_DEBUG("carp6_input: packet size %u too small\n", len);
675 		return (IPPROTO_DONE);
676 	}
677 
678 
679 	/* verify the CARP checksum */
680 	m->m_data += *offp;
681 	if (carp_cksum(m, sizeof(*ch))) {
682 		CARPSTATS_INC(carps_badsum);
683 		CARP_DEBUG("carp6_input: checksum failed, on %s\n",
684 		    m->m_pkthdr.rcvif->if_xname);
685 		m_freem(m);
686 		return (IPPROTO_DONE);
687 	}
688 	m->m_data -= *offp;
689 
690 	carp_input_c(m, ch, AF_INET6);
691 	return (IPPROTO_DONE);
692 }
693 #endif /* INET6 */
694 
695 static void
696 carp_input_c(struct mbuf *m, struct carp_header *ch, sa_family_t af)
697 {
698 	struct ifnet *ifp = m->m_pkthdr.rcvif;
699 	struct carp_softc *sc;
700 	u_int64_t tmp_counter;
701 	struct timeval sc_tv, ch_tv;
702 
703 	/* verify that the VHID is valid on the receiving interface */
704 	CARP_LOCK(ifp->if_carp);
705 	TAILQ_FOREACH(sc, &((struct carp_if *)ifp->if_carp)->vhif_vrs, sc_list)
706 		if (sc->sc_vhid == ch->carp_vhid)
707 			break;
708 
709 	if (!sc || !((SC2IFP(sc)->if_flags & IFF_UP) &&
710 	    (SC2IFP(sc)->if_drv_flags & IFF_DRV_RUNNING))) {
711 		CARPSTATS_INC(carps_badvhid);
712 		CARP_UNLOCK(ifp->if_carp);
713 		m_freem(m);
714 		return;
715 	}
716 
717 	getmicrotime(&SC2IFP(sc)->if_lastchange);
718 	SC2IFP(sc)->if_ipackets++;
719 	SC2IFP(sc)->if_ibytes += m->m_pkthdr.len;
720 
721 	if (bpf_peers_present(SC2IFP(sc)->if_bpf)) {
722 		struct ip *ip = mtod(m, struct ip *);
723 		uint32_t af1 = af;
724 
725 		/* BPF wants net byte order */
726 		ip->ip_len = htons(ip->ip_len + (ip->ip_hl << 2));
727 		ip->ip_off = htons(ip->ip_off);
728 		bpf_mtap2(SC2IFP(sc)->if_bpf, &af1, sizeof(af1), m);
729 	}
730 
731 	/* verify the CARP version. */
732 	if (ch->carp_version != CARP_VERSION) {
733 		CARPSTATS_INC(carps_badver);
734 		SC2IFP(sc)->if_ierrors++;
735 		CARP_UNLOCK(ifp->if_carp);
736 		CARP_DEBUG("%s; invalid version %d\n",
737 		    SC2IFP(sc)->if_xname,
738 		    ch->carp_version);
739 		m_freem(m);
740 		return;
741 	}
742 
743 	/* verify the hash */
744 	if (carp_hmac_verify(sc, ch->carp_counter, ch->carp_md)) {
745 		CARPSTATS_INC(carps_badauth);
746 		SC2IFP(sc)->if_ierrors++;
747 		CARP_UNLOCK(ifp->if_carp);
748 		CARP_DEBUG("%s: incorrect hash\n", SC2IFP(sc)->if_xname);
749 		m_freem(m);
750 		return;
751 	}
752 
753 	tmp_counter = ntohl(ch->carp_counter[0]);
754 	tmp_counter = tmp_counter<<32;
755 	tmp_counter += ntohl(ch->carp_counter[1]);
756 
757 	/* XXX Replay protection goes here */
758 
759 	sc->sc_init_counter = 0;
760 	sc->sc_counter = tmp_counter;
761 
762 	sc_tv.tv_sec = sc->sc_advbase;
763 	if (carp_suppress_preempt && sc->sc_advskew <  240)
764 		sc_tv.tv_usec = 240 * 1000000 / 256;
765 	else
766 		sc_tv.tv_usec = sc->sc_advskew * 1000000 / 256;
767 	ch_tv.tv_sec = ch->carp_advbase;
768 	ch_tv.tv_usec = ch->carp_advskew * 1000000 / 256;
769 
770 	switch (sc->sc_state) {
771 	case INIT:
772 		break;
773 	case MASTER:
774 		/*
775 		 * If we receive an advertisement from a master who's going to
776 		 * be more frequent than us, go into BACKUP state.
777 		 */
778 		if (timevalcmp(&sc_tv, &ch_tv, >) ||
779 		    timevalcmp(&sc_tv, &ch_tv, ==)) {
780 			callout_stop(&sc->sc_ad_tmo);
781 			CARP_LOG("%s: MASTER -> BACKUP "
782 			   "(more frequent advertisement received)\n",
783 			   SC2IFP(sc)->if_xname);
784 			carp_set_state(sc, BACKUP);
785 			carp_setrun(sc, 0);
786 			carp_setroute(sc, RTM_DELETE);
787 		}
788 		break;
789 	case BACKUP:
790 		/*
791 		 * If we're pre-empting masters who advertise slower than us,
792 		 * and this one claims to be slower, treat him as down.
793 		 */
794 		if (carp_opts[CARPCTL_PREEMPT] &&
795 		    timevalcmp(&sc_tv, &ch_tv, <)) {
796 			CARP_LOG("%s: BACKUP -> MASTER "
797 			    "(preempting a slower master)\n",
798 			    SC2IFP(sc)->if_xname);
799 			carp_master_down_locked(sc);
800 			break;
801 		}
802 
803 		/*
804 		 *  If the master is going to advertise at such a low frequency
805 		 *  that he's guaranteed to time out, we'd might as well just
806 		 *  treat him as timed out now.
807 		 */
808 		sc_tv.tv_sec = sc->sc_advbase * 3;
809 		if (timevalcmp(&sc_tv, &ch_tv, <)) {
810 			CARP_LOG("%s: BACKUP -> MASTER "
811 			    "(master timed out)\n",
812 			    SC2IFP(sc)->if_xname);
813 			carp_master_down_locked(sc);
814 			break;
815 		}
816 
817 		/*
818 		 * Otherwise, we reset the counter and wait for the next
819 		 * advertisement.
820 		 */
821 		carp_setrun(sc, af);
822 		break;
823 	}
824 
825 	CARP_UNLOCK(ifp->if_carp);
826 
827 	m_freem(m);
828 	return;
829 }
830 
831 static int
832 carp_prepare_ad(struct mbuf *m, struct carp_softc *sc, struct carp_header *ch)
833 {
834 	struct m_tag *mtag;
835 	struct ifnet *ifp = SC2IFP(sc);
836 
837 	if (sc->sc_init_counter) {
838 		/* this could also be seconds since unix epoch */
839 		sc->sc_counter = arc4random();
840 		sc->sc_counter = sc->sc_counter << 32;
841 		sc->sc_counter += arc4random();
842 	} else
843 		sc->sc_counter++;
844 
845 	ch->carp_counter[0] = htonl((sc->sc_counter>>32)&0xffffffff);
846 	ch->carp_counter[1] = htonl(sc->sc_counter&0xffffffff);
847 
848 	carp_hmac_generate(sc, ch->carp_counter, ch->carp_md);
849 
850 	/* Tag packet for carp_output */
851 	mtag = m_tag_get(PACKET_TAG_CARP, sizeof(struct ifnet *), M_NOWAIT);
852 	if (mtag == NULL) {
853 		m_freem(m);
854 		SC2IFP(sc)->if_oerrors++;
855 		return (ENOMEM);
856 	}
857 	bcopy(&ifp, (caddr_t)(mtag + 1), sizeof(struct ifnet *));
858 	m_tag_prepend(m, mtag);
859 
860 	return (0);
861 }
862 
863 static void
864 carp_send_ad_all(void)
865 {
866 	struct carp_softc *sc;
867 
868 	mtx_lock(&carp_mtx);
869 	LIST_FOREACH(sc, &carpif_list, sc_next) {
870 		if (sc->sc_carpdev == NULL)
871 			continue;
872 		CARP_SCLOCK(sc);
873 		if ((SC2IFP(sc)->if_flags & IFF_UP) &&
874 		    (SC2IFP(sc)->if_drv_flags & IFF_DRV_RUNNING) &&
875 		     sc->sc_state == MASTER)
876 			carp_send_ad_locked(sc);
877 		CARP_SCUNLOCK(sc);
878 	}
879 	mtx_unlock(&carp_mtx);
880 }
881 
882 static void
883 carp_send_ad(void *v)
884 {
885 	struct carp_softc *sc = v;
886 
887 	CARP_SCLOCK(sc);
888 	carp_send_ad_locked(sc);
889 	CARP_SCUNLOCK(sc);
890 }
891 
892 static void
893 carp_send_ad_locked(struct carp_softc *sc)
894 {
895 	struct carp_header ch;
896 	struct timeval tv;
897 	struct carp_header *ch_ptr;
898 	struct mbuf *m;
899 	int len, advbase, advskew;
900 
901 	CARP_SCLOCK_ASSERT(sc);
902 
903 	/* bow out if we've lost our UPness or RUNNINGuiness */
904 	if (!((SC2IFP(sc)->if_flags & IFF_UP) &&
905 	    (SC2IFP(sc)->if_drv_flags & IFF_DRV_RUNNING))) {
906 		advbase = 255;
907 		advskew = 255;
908 	} else {
909 		advbase = sc->sc_advbase;
910 		if (!carp_suppress_preempt || sc->sc_advskew > 240)
911 			advskew = sc->sc_advskew;
912 		else
913 			advskew = 240;
914 		tv.tv_sec = advbase;
915 		tv.tv_usec = advskew * 1000000 / 256;
916 	}
917 
918 	ch.carp_version = CARP_VERSION;
919 	ch.carp_type = CARP_ADVERTISEMENT;
920 	ch.carp_vhid = sc->sc_vhid;
921 	ch.carp_advbase = advbase;
922 	ch.carp_advskew = advskew;
923 	ch.carp_authlen = 7;	/* XXX DEFINE */
924 	ch.carp_pad1 = 0;	/* must be zero */
925 	ch.carp_cksum = 0;
926 
927 #ifdef INET
928 	if (sc->sc_ia) {
929 		struct ip *ip;
930 
931 		MGETHDR(m, M_DONTWAIT, MT_HEADER);
932 		if (m == NULL) {
933 			SC2IFP(sc)->if_oerrors++;
934 			CARPSTATS_INC(carps_onomem);
935 			/* XXX maybe less ? */
936 			if (advbase != 255 || advskew != 255)
937 				callout_reset(&sc->sc_ad_tmo, tvtohz(&tv),
938 				    carp_send_ad, sc);
939 			return;
940 		}
941 		len = sizeof(*ip) + sizeof(ch);
942 		m->m_pkthdr.len = len;
943 		m->m_pkthdr.rcvif = NULL;
944 		m->m_len = len;
945 		MH_ALIGN(m, m->m_len);
946 		m->m_flags |= M_MCAST;
947 		ip = mtod(m, struct ip *);
948 		ip->ip_v = IPVERSION;
949 		ip->ip_hl = sizeof(*ip) >> 2;
950 		ip->ip_tos = IPTOS_LOWDELAY;
951 		ip->ip_len = len;
952 		ip->ip_id = ip_newid();
953 		ip->ip_off = IP_DF;
954 		ip->ip_ttl = CARP_DFLTTL;
955 		ip->ip_p = IPPROTO_CARP;
956 		ip->ip_sum = 0;
957 		ip->ip_src.s_addr = sc->sc_ia->ia_addr.sin_addr.s_addr;
958 		ip->ip_dst.s_addr = htonl(INADDR_CARP_GROUP);
959 
960 		ch_ptr = (struct carp_header *)(&ip[1]);
961 		bcopy(&ch, ch_ptr, sizeof(ch));
962 		if (carp_prepare_ad(m, sc, ch_ptr))
963 			return;
964 
965 		m->m_data += sizeof(*ip);
966 		ch_ptr->carp_cksum = carp_cksum(m, len - sizeof(*ip));
967 		m->m_data -= sizeof(*ip);
968 
969 		getmicrotime(&SC2IFP(sc)->if_lastchange);
970 		SC2IFP(sc)->if_opackets++;
971 		SC2IFP(sc)->if_obytes += len;
972 		CARPSTATS_INC(carps_opackets);
973 
974 		if (ip_output(m, NULL, NULL, IP_RAWOUTPUT, &sc->sc_imo, NULL)) {
975 			SC2IFP(sc)->if_oerrors++;
976 			if (sc->sc_sendad_errors < INT_MAX)
977 				sc->sc_sendad_errors++;
978 			if (sc->sc_sendad_errors == CARP_SENDAD_MAX_ERRORS) {
979 				carp_suppress_preempt++;
980 				if (carp_suppress_preempt == 1) {
981 					CARP_SCUNLOCK(sc);
982 					carp_send_ad_all();
983 					CARP_SCLOCK(sc);
984 				}
985 			}
986 			sc->sc_sendad_success = 0;
987 		} else {
988 			if (sc->sc_sendad_errors >= CARP_SENDAD_MAX_ERRORS) {
989 				if (++sc->sc_sendad_success >=
990 				    CARP_SENDAD_MIN_SUCCESS) {
991 					carp_suppress_preempt--;
992 					sc->sc_sendad_errors = 0;
993 				}
994 			} else
995 				sc->sc_sendad_errors = 0;
996 		}
997 	}
998 #endif /* INET */
999 #ifdef INET6
1000 	if (sc->sc_ia6) {
1001 		struct ip6_hdr *ip6;
1002 
1003 		MGETHDR(m, M_DONTWAIT, MT_HEADER);
1004 		if (m == NULL) {
1005 			SC2IFP(sc)->if_oerrors++;
1006 			CARPSTATS_INC(carps_onomem);
1007 			/* XXX maybe less ? */
1008 			if (advbase != 255 || advskew != 255)
1009 				callout_reset(&sc->sc_ad_tmo, tvtohz(&tv),
1010 				    carp_send_ad, sc);
1011 			return;
1012 		}
1013 		len = sizeof(*ip6) + sizeof(ch);
1014 		m->m_pkthdr.len = len;
1015 		m->m_pkthdr.rcvif = NULL;
1016 		m->m_len = len;
1017 		MH_ALIGN(m, m->m_len);
1018 		m->m_flags |= M_MCAST;
1019 		ip6 = mtod(m, struct ip6_hdr *);
1020 		bzero(ip6, sizeof(*ip6));
1021 		ip6->ip6_vfc |= IPV6_VERSION;
1022 		ip6->ip6_hlim = CARP_DFLTTL;
1023 		ip6->ip6_nxt = IPPROTO_CARP;
1024 		bcopy(&sc->sc_ia6->ia_addr.sin6_addr, &ip6->ip6_src,
1025 		    sizeof(struct in6_addr));
1026 		/* set the multicast destination */
1027 
1028 		ip6->ip6_dst.s6_addr16[0] = htons(0xff02);
1029 		ip6->ip6_dst.s6_addr8[15] = 0x12;
1030 		if (in6_setscope(&ip6->ip6_dst, sc->sc_carpdev, NULL) != 0) {
1031 			SC2IFP(sc)->if_oerrors++;
1032 			m_freem(m);
1033 			CARP_DEBUG("%s: in6_setscope failed\n", __func__);
1034 			return;
1035 		}
1036 
1037 		ch_ptr = (struct carp_header *)(&ip6[1]);
1038 		bcopy(&ch, ch_ptr, sizeof(ch));
1039 		if (carp_prepare_ad(m, sc, ch_ptr))
1040 			return;
1041 
1042 		m->m_data += sizeof(*ip6);
1043 		ch_ptr->carp_cksum = carp_cksum(m, len - sizeof(*ip6));
1044 		m->m_data -= sizeof(*ip6);
1045 
1046 		getmicrotime(&SC2IFP(sc)->if_lastchange);
1047 		SC2IFP(sc)->if_opackets++;
1048 		SC2IFP(sc)->if_obytes += len;
1049 		CARPSTATS_INC(carps_opackets6);
1050 
1051 		if (ip6_output(m, NULL, NULL, 0, &sc->sc_im6o, NULL, NULL)) {
1052 			SC2IFP(sc)->if_oerrors++;
1053 			if (sc->sc_sendad_errors < INT_MAX)
1054 				sc->sc_sendad_errors++;
1055 			if (sc->sc_sendad_errors == CARP_SENDAD_MAX_ERRORS) {
1056 				carp_suppress_preempt++;
1057 				if (carp_suppress_preempt == 1) {
1058 					CARP_SCUNLOCK(sc);
1059 					carp_send_ad_all();
1060 					CARP_SCLOCK(sc);
1061 				}
1062 			}
1063 			sc->sc_sendad_success = 0;
1064 		} else {
1065 			if (sc->sc_sendad_errors >= CARP_SENDAD_MAX_ERRORS) {
1066 				if (++sc->sc_sendad_success >=
1067 				    CARP_SENDAD_MIN_SUCCESS) {
1068 					carp_suppress_preempt--;
1069 					sc->sc_sendad_errors = 0;
1070 				}
1071 			} else
1072 				sc->sc_sendad_errors = 0;
1073 		}
1074 	}
1075 #endif /* INET6 */
1076 
1077 	if (advbase != 255 || advskew != 255)
1078 		callout_reset(&sc->sc_ad_tmo, tvtohz(&tv),
1079 		    carp_send_ad, sc);
1080 
1081 }
1082 
1083 /*
1084  * Broadcast a gratuitous ARP request containing
1085  * the virtual router MAC address for each IP address
1086  * associated with the virtual router.
1087  */
1088 static void
1089 carp_send_arp(struct carp_softc *sc)
1090 {
1091 	struct ifaddr *ifa;
1092 
1093 	TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
1094 
1095 		if (ifa->ifa_addr->sa_family != AF_INET)
1096 			continue;
1097 
1098 /*		arprequest(sc->sc_carpdev, &in, &in, IF_LLADDR(sc->sc_ifp)); */
1099 		arp_ifinit2(sc->sc_carpdev, ifa, IF_LLADDR(sc->sc_ifp));
1100 
1101 		DELAY(1000);	/* XXX */
1102 	}
1103 }
1104 
1105 #ifdef INET6
1106 static void
1107 carp_send_na(struct carp_softc *sc)
1108 {
1109 	struct ifaddr *ifa;
1110 	struct in6_addr *in6;
1111 	static struct in6_addr mcast = IN6ADDR_LINKLOCAL_ALLNODES_INIT;
1112 
1113 	TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
1114 
1115 		if (ifa->ifa_addr->sa_family != AF_INET6)
1116 			continue;
1117 
1118 		in6 = &ifatoia6(ifa)->ia_addr.sin6_addr;
1119 		nd6_na_output(sc->sc_carpdev, &mcast, in6,
1120 		    ND_NA_FLAG_OVERRIDE, 1, NULL);
1121 		DELAY(1000);	/* XXX */
1122 	}
1123 }
1124 #endif /* INET6 */
1125 
1126 static int
1127 carp_addrcount(struct carp_if *cif, struct in_ifaddr *ia, int type)
1128 {
1129 	struct carp_softc *vh;
1130 	struct ifaddr *ifa;
1131 	int count = 0;
1132 
1133 	CARP_LOCK_ASSERT(cif);
1134 
1135 	TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list) {
1136 		if ((type == CARP_COUNT_RUNNING &&
1137 		    (SC2IFP(vh)->if_flags & IFF_UP) &&
1138 		    (SC2IFP(vh)->if_drv_flags & IFF_DRV_RUNNING)) ||
1139 		    (type == CARP_COUNT_MASTER && vh->sc_state == MASTER)) {
1140 			IF_ADDR_LOCK(SC2IFP(vh));
1141 			TAILQ_FOREACH(ifa, &SC2IFP(vh)->if_addrlist,
1142 			    ifa_list) {
1143 				if (ifa->ifa_addr->sa_family == AF_INET &&
1144 				    ia->ia_addr.sin_addr.s_addr ==
1145 				    ifatoia(ifa)->ia_addr.sin_addr.s_addr)
1146 					count++;
1147 			}
1148 			IF_ADDR_UNLOCK(SC2IFP(vh));
1149 		}
1150 	}
1151 	return (count);
1152 }
1153 
1154 int
1155 carp_iamatch(struct ifnet *ifp, struct in_ifaddr *ia,
1156     struct in_addr *isaddr, u_int8_t **enaddr)
1157 {
1158 	struct carp_if *cif;
1159 	struct carp_softc *vh;
1160 	int index, count = 0;
1161 	struct ifaddr *ifa;
1162 
1163 	cif = ifp->if_carp;
1164 	CARP_LOCK(cif);
1165 
1166 	if (carp_opts[CARPCTL_ARPBALANCE]) {
1167 		/*
1168 		 * XXX proof of concept implementation.
1169 		 * We use the source ip to decide which virtual host should
1170 		 * handle the request. If we're master of that virtual host,
1171 		 * then we respond, otherwise, just drop the arp packet on
1172 		 * the floor.
1173 		 */
1174 		count = carp_addrcount(cif, ia, CARP_COUNT_RUNNING);
1175 		if (count == 0) {
1176 			/* should never reach this */
1177 			CARP_UNLOCK(cif);
1178 			return (0);
1179 		}
1180 
1181 		/* this should be a hash, like pf_hash() */
1182 		index = ntohl(isaddr->s_addr) % count;
1183 		count = 0;
1184 
1185 		TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list) {
1186 			if ((SC2IFP(vh)->if_flags & IFF_UP) &&
1187 			    (SC2IFP(vh)->if_drv_flags & IFF_DRV_RUNNING)) {
1188 				IF_ADDR_LOCK(SC2IFP(vh));
1189 				TAILQ_FOREACH(ifa, &SC2IFP(vh)->if_addrlist,
1190 				    ifa_list) {
1191 					if (ifa->ifa_addr->sa_family ==
1192 					    AF_INET &&
1193 					    ia->ia_addr.sin_addr.s_addr ==
1194 					    ifatoia(ifa)->ia_addr.sin_addr.s_addr) {
1195 						if (count == index) {
1196 							if (vh->sc_state ==
1197 							    MASTER) {
1198 								*enaddr = IF_LLADDR(vh->sc_ifp);
1199 								IF_ADDR_UNLOCK(SC2IFP(vh));
1200 								CARP_UNLOCK(cif);
1201 								return (1);
1202 							} else {
1203 								IF_ADDR_UNLOCK(SC2IFP(vh));
1204 								CARP_UNLOCK(cif);
1205 								return (0);
1206 							}
1207 						}
1208 						count++;
1209 					}
1210 				}
1211 				IF_ADDR_UNLOCK(SC2IFP(vh));
1212 			}
1213 		}
1214 	} else {
1215 		TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list) {
1216 			if ((SC2IFP(vh)->if_flags & IFF_UP) &&
1217 			    (SC2IFP(vh)->if_drv_flags & IFF_DRV_RUNNING) &&
1218 			    ia->ia_ifp == SC2IFP(vh) &&
1219 			    vh->sc_state == MASTER) {
1220 				*enaddr = IF_LLADDR(vh->sc_ifp);
1221 				CARP_UNLOCK(cif);
1222 				return (1);
1223 			}
1224 		}
1225 	}
1226 	CARP_UNLOCK(cif);
1227 	return (0);
1228 }
1229 
1230 #ifdef INET6
1231 struct ifaddr *
1232 carp_iamatch6(struct ifnet *ifp, struct in6_addr *taddr)
1233 {
1234 	struct carp_if *cif;
1235 	struct carp_softc *vh;
1236 	struct ifaddr *ifa;
1237 
1238 	cif = ifp->if_carp;
1239 	CARP_LOCK(cif);
1240 	TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list) {
1241 		IF_ADDR_LOCK(SC2IFP(vh));
1242 		TAILQ_FOREACH(ifa, &SC2IFP(vh)->if_addrlist, ifa_list) {
1243 			if (IN6_ARE_ADDR_EQUAL(taddr,
1244 			    &ifatoia6(ifa)->ia_addr.sin6_addr) &&
1245  			    (SC2IFP(vh)->if_flags & IFF_UP) &&
1246 			    (SC2IFP(vh)->if_drv_flags & IFF_DRV_RUNNING) &&
1247 			    vh->sc_state == MASTER) {
1248 				ifa_ref(ifa);
1249 				IF_ADDR_UNLOCK(SC2IFP(vh));
1250 			    	CARP_UNLOCK(cif);
1251 				return (ifa);
1252 			}
1253 		}
1254 		IF_ADDR_UNLOCK(SC2IFP(vh));
1255 	}
1256 	CARP_UNLOCK(cif);
1257 
1258 	return (NULL);
1259 }
1260 
1261 caddr_t
1262 carp_macmatch6(struct ifnet *ifp, struct mbuf *m, const struct in6_addr *taddr)
1263 {
1264 	struct m_tag *mtag;
1265 	struct carp_if *cif;
1266 	struct carp_softc *sc;
1267 	struct ifaddr *ifa;
1268 
1269 	cif = ifp->if_carp;
1270 	CARP_LOCK(cif);
1271 	TAILQ_FOREACH(sc, &cif->vhif_vrs, sc_list) {
1272 		IF_ADDR_LOCK(SC2IFP(sc));
1273 		TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
1274 			if (IN6_ARE_ADDR_EQUAL(taddr,
1275 			    &ifatoia6(ifa)->ia_addr.sin6_addr) &&
1276  			    (SC2IFP(sc)->if_flags & IFF_UP) &&
1277 			    (SC2IFP(sc)->if_drv_flags & IFF_DRV_RUNNING)) {
1278 				struct ifnet *ifp = SC2IFP(sc);
1279 				mtag = m_tag_get(PACKET_TAG_CARP,
1280 				    sizeof(struct ifnet *), M_NOWAIT);
1281 				if (mtag == NULL) {
1282 					/* better a bit than nothing */
1283 					IF_ADDR_UNLOCK(SC2IFP(sc));
1284 					CARP_UNLOCK(cif);
1285 					return (IF_LLADDR(sc->sc_ifp));
1286 				}
1287 				bcopy(&ifp, (caddr_t)(mtag + 1),
1288 				    sizeof(struct ifnet *));
1289 				m_tag_prepend(m, mtag);
1290 
1291 				IF_ADDR_UNLOCK(SC2IFP(sc));
1292 				CARP_UNLOCK(cif);
1293 				return (IF_LLADDR(sc->sc_ifp));
1294 			}
1295 		}
1296 		IF_ADDR_UNLOCK(SC2IFP(sc));
1297 	}
1298 	CARP_UNLOCK(cif);
1299 
1300 	return (NULL);
1301 }
1302 #endif
1303 
1304 struct ifnet *
1305 carp_forus(struct ifnet *ifp, u_char *dhost)
1306 {
1307 	struct carp_if *cif;
1308 	struct carp_softc *vh;
1309 	u_int8_t *ena = dhost;
1310 
1311 	if (ena[0] || ena[1] || ena[2] != 0x5e || ena[3] || ena[4] != 1)
1312 		return (NULL);
1313 
1314 	cif = ifp->if_carp;
1315 	CARP_LOCK(cif);
1316 	TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list)
1317 		if ((SC2IFP(vh)->if_flags & IFF_UP) &&
1318 		    (SC2IFP(vh)->if_drv_flags & IFF_DRV_RUNNING) &&
1319 		    vh->sc_state == MASTER &&
1320 		    !bcmp(dhost, IF_LLADDR(vh->sc_ifp), ETHER_ADDR_LEN)) {
1321 		    	CARP_UNLOCK(cif);
1322 			return (SC2IFP(vh));
1323 		}
1324 
1325     	CARP_UNLOCK(cif);
1326 	return (NULL);
1327 }
1328 
1329 static void
1330 carp_master_down(void *v)
1331 {
1332 	struct carp_softc *sc = v;
1333 
1334 	CARP_SCLOCK(sc);
1335 	carp_master_down_locked(sc);
1336 	CARP_SCUNLOCK(sc);
1337 }
1338 
1339 static void
1340 carp_master_down_locked(struct carp_softc *sc)
1341 {
1342 	if (sc->sc_carpdev)
1343 		CARP_SCLOCK_ASSERT(sc);
1344 
1345 	switch (sc->sc_state) {
1346 	case INIT:
1347 		printf("%s: master_down event in INIT state\n",
1348 		    SC2IFP(sc)->if_xname);
1349 		break;
1350 	case MASTER:
1351 		break;
1352 	case BACKUP:
1353 		carp_set_state(sc, MASTER);
1354 		carp_send_ad_locked(sc);
1355 		carp_send_arp(sc);
1356 #ifdef INET6
1357 		carp_send_na(sc);
1358 #endif /* INET6 */
1359 		carp_setrun(sc, 0);
1360 		carp_setroute(sc, RTM_ADD);
1361 		break;
1362 	}
1363 }
1364 
1365 /*
1366  * When in backup state, af indicates whether to reset the master down timer
1367  * for v4 or v6. If it's set to zero, reset the ones which are already pending.
1368  */
1369 static void
1370 carp_setrun(struct carp_softc *sc, sa_family_t af)
1371 {
1372 	struct timeval tv;
1373 
1374 	if (sc->sc_carpdev == NULL) {
1375 		SC2IFP(sc)->if_drv_flags &= ~IFF_DRV_RUNNING;
1376 		carp_set_state(sc, INIT);
1377 		return;
1378 	} else
1379 		CARP_SCLOCK_ASSERT(sc);
1380 
1381 	if (SC2IFP(sc)->if_flags & IFF_UP &&
1382 	    sc->sc_vhid > 0 && (sc->sc_naddrs || sc->sc_naddrs6) &&
1383 	    sc->sc_carpdev->if_link_state == LINK_STATE_UP)
1384 		SC2IFP(sc)->if_drv_flags |= IFF_DRV_RUNNING;
1385 	else {
1386 		SC2IFP(sc)->if_drv_flags &= ~IFF_DRV_RUNNING;
1387 		carp_setroute(sc, RTM_DELETE);
1388 		return;
1389 	}
1390 
1391 	switch (sc->sc_state) {
1392 	case INIT:
1393 		if (carp_opts[CARPCTL_PREEMPT] && !carp_suppress_preempt) {
1394 			carp_send_ad_locked(sc);
1395 			carp_send_arp(sc);
1396 #ifdef INET6
1397 			carp_send_na(sc);
1398 #endif /* INET6 */
1399 			CARP_LOG("%s: INIT -> MASTER (preempting)\n",
1400 			    SC2IFP(sc)->if_xname);
1401 			carp_set_state(sc, MASTER);
1402 			carp_setroute(sc, RTM_ADD);
1403 		} else {
1404 			CARP_LOG("%s: INIT -> BACKUP\n", SC2IFP(sc)->if_xname);
1405 			carp_set_state(sc, BACKUP);
1406 			carp_setroute(sc, RTM_DELETE);
1407 			carp_setrun(sc, 0);
1408 		}
1409 		break;
1410 	case BACKUP:
1411 		callout_stop(&sc->sc_ad_tmo);
1412 		tv.tv_sec = 3 * sc->sc_advbase;
1413 		tv.tv_usec = sc->sc_advskew * 1000000 / 256;
1414 		switch (af) {
1415 #ifdef INET
1416 		case AF_INET:
1417 			callout_reset(&sc->sc_md_tmo, tvtohz(&tv),
1418 			    carp_master_down, sc);
1419 			break;
1420 #endif /* INET */
1421 #ifdef INET6
1422 		case AF_INET6:
1423 			callout_reset(&sc->sc_md6_tmo, tvtohz(&tv),
1424 			    carp_master_down, sc);
1425 			break;
1426 #endif /* INET6 */
1427 		default:
1428 			if (sc->sc_naddrs)
1429 				callout_reset(&sc->sc_md_tmo, tvtohz(&tv),
1430 				    carp_master_down, sc);
1431 			if (sc->sc_naddrs6)
1432 				callout_reset(&sc->sc_md6_tmo, tvtohz(&tv),
1433 				    carp_master_down, sc);
1434 			break;
1435 		}
1436 		break;
1437 	case MASTER:
1438 		tv.tv_sec = sc->sc_advbase;
1439 		tv.tv_usec = sc->sc_advskew * 1000000 / 256;
1440 		callout_reset(&sc->sc_ad_tmo, tvtohz(&tv),
1441 		    carp_send_ad, sc);
1442 		break;
1443 	}
1444 }
1445 
1446 static void
1447 carp_multicast_cleanup(struct carp_softc *sc)
1448 {
1449 	struct ip_moptions *imo = &sc->sc_imo;
1450 	u_int16_t n = imo->imo_num_memberships;
1451 
1452 	/* Clean up our own multicast memberships */
1453 	while (n-- > 0) {
1454 		if (imo->imo_membership[n] != NULL) {
1455 			in_delmulti(imo->imo_membership[n]);
1456 			imo->imo_membership[n] = NULL;
1457 		}
1458 	}
1459 	KASSERT(imo->imo_mfilters == NULL,
1460 	   ("%s: imo_mfilters != NULL", __func__));
1461 	imo->imo_num_memberships = 0;
1462 	imo->imo_multicast_ifp = NULL;
1463 }
1464 
1465 #ifdef INET6
1466 static void
1467 carp_multicast6_cleanup(struct carp_softc *sc)
1468 {
1469 	struct ip6_moptions *im6o = &sc->sc_im6o;
1470 	u_int16_t n = im6o->im6o_num_memberships;
1471 
1472 	while (n-- > 0) {
1473 		if (im6o->im6o_membership[n] != NULL) {
1474 			in6_mc_leave(im6o->im6o_membership[n], NULL);
1475 			im6o->im6o_membership[n] = NULL;
1476 		}
1477 	}
1478 	KASSERT(im6o->im6o_mfilters == NULL,
1479 	   ("%s: im6o_mfilters != NULL", __func__));
1480 	im6o->im6o_num_memberships = 0;
1481 	im6o->im6o_multicast_ifp = NULL;
1482 }
1483 #endif
1484 
1485 static int
1486 carp_set_addr(struct carp_softc *sc, struct sockaddr_in *sin)
1487 {
1488 	struct ifnet *ifp;
1489 	struct carp_if *cif;
1490 	struct in_ifaddr *ia, *ia_if;
1491 	struct ip_moptions *imo = &sc->sc_imo;
1492 	struct in_addr addr;
1493 	u_long iaddr = htonl(sin->sin_addr.s_addr);
1494 	int own, error;
1495 
1496 	if (sin->sin_addr.s_addr == 0) {
1497 		if (!(SC2IFP(sc)->if_flags & IFF_UP))
1498 			carp_set_state(sc, INIT);
1499 		if (sc->sc_naddrs)
1500 			SC2IFP(sc)->if_flags |= IFF_UP;
1501 		if (sc->sc_carpdev)
1502 			CARP_SCLOCK(sc);
1503 		carp_setrun(sc, 0);
1504 		if (sc->sc_carpdev)
1505 			CARP_SCUNLOCK(sc);
1506 		return (0);
1507 	}
1508 
1509 	/* we have to do it by hands to check we won't match on us */
1510 	ia_if = NULL; own = 0;
1511 	IN_IFADDR_RLOCK();
1512 	TAILQ_FOREACH(ia, &V_in_ifaddrhead, ia_link) {
1513 		/* and, yeah, we need a multicast-capable iface too */
1514 		if (ia->ia_ifp != SC2IFP(sc) &&
1515 		    (ia->ia_ifp->if_flags & IFF_MULTICAST) &&
1516 		    (iaddr & ia->ia_subnetmask) == ia->ia_subnet) {
1517 			if (!ia_if)
1518 				ia_if = ia;
1519 			if (sin->sin_addr.s_addr ==
1520 			    ia->ia_addr.sin_addr.s_addr)
1521 				own++;
1522 		}
1523 	}
1524 
1525 	if (!ia_if) {
1526 		IN_IFADDR_RUNLOCK();
1527 		return (EADDRNOTAVAIL);
1528 	}
1529 
1530 	ia = ia_if;
1531 	ifa_ref(&ia->ia_ifa);
1532 	IN_IFADDR_RUNLOCK();
1533 
1534 	ifp = ia->ia_ifp;
1535 
1536 	if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0 ||
1537 	    (imo->imo_multicast_ifp && imo->imo_multicast_ifp != ifp)) {
1538 		ifa_free(&ia->ia_ifa);
1539 		return (EADDRNOTAVAIL);
1540 	}
1541 
1542 	if (imo->imo_num_memberships == 0) {
1543 		addr.s_addr = htonl(INADDR_CARP_GROUP);
1544 		if ((imo->imo_membership[0] = in_addmulti(&addr, ifp)) ==
1545 		    NULL) {
1546 			ifa_free(&ia->ia_ifa);
1547 			return (ENOBUFS);
1548 		}
1549 		imo->imo_num_memberships++;
1550 		imo->imo_multicast_ifp = ifp;
1551 		imo->imo_multicast_ttl = CARP_DFLTTL;
1552 		imo->imo_multicast_loop = 0;
1553 	}
1554 
1555 	if (!ifp->if_carp) {
1556 
1557 		cif = malloc(sizeof(*cif), M_CARP,
1558 		    M_WAITOK|M_ZERO);
1559 		if (!cif) {
1560 			error = ENOBUFS;
1561 			goto cleanup;
1562 		}
1563 		if ((error = ifpromisc(ifp, 1))) {
1564 			free(cif, M_CARP);
1565 			goto cleanup;
1566 		}
1567 
1568 		CARP_LOCK_INIT(cif);
1569 		CARP_LOCK(cif);
1570 		cif->vhif_ifp = ifp;
1571 		TAILQ_INIT(&cif->vhif_vrs);
1572 		ifp->if_carp = cif;
1573 
1574 	} else {
1575 		struct carp_softc *vr;
1576 
1577 		cif = (struct carp_if *)ifp->if_carp;
1578 		CARP_LOCK(cif);
1579 		TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list)
1580 			if (vr != sc && vr->sc_vhid == sc->sc_vhid) {
1581 				CARP_UNLOCK(cif);
1582 				error = EEXIST;
1583 				goto cleanup;
1584 			}
1585 	}
1586 	sc->sc_ia = ia;
1587 	sc->sc_carpdev = ifp;
1588 
1589 	{ /* XXX prevent endless loop if already in queue */
1590 	struct carp_softc *vr, *after = NULL;
1591 	int myself = 0;
1592 	cif = (struct carp_if *)ifp->if_carp;
1593 
1594 	/* XXX: cif should not change, right? So we still hold the lock */
1595 	CARP_LOCK_ASSERT(cif);
1596 
1597 	TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list) {
1598 		if (vr == sc)
1599 			myself = 1;
1600 		if (vr->sc_vhid < sc->sc_vhid)
1601 			after = vr;
1602 	}
1603 
1604 	if (!myself) {
1605 		/* We're trying to keep things in order */
1606 		if (after == NULL) {
1607 			TAILQ_INSERT_TAIL(&cif->vhif_vrs, sc, sc_list);
1608 		} else {
1609 			TAILQ_INSERT_AFTER(&cif->vhif_vrs, after, sc, sc_list);
1610 		}
1611 		cif->vhif_nvrs++;
1612 	}
1613 	}
1614 
1615 	sc->sc_naddrs++;
1616 	SC2IFP(sc)->if_flags |= IFF_UP;
1617 	if (own)
1618 		sc->sc_advskew = 0;
1619 	carp_sc_state_locked(sc);
1620 	carp_setrun(sc, 0);
1621 
1622 	CARP_UNLOCK(cif);
1623 	ifa_free(&ia->ia_ifa);	/* XXXRW: should hold reference for softc. */
1624 
1625 	return (0);
1626 
1627 cleanup:
1628 	in_delmulti(imo->imo_membership[--imo->imo_num_memberships]);
1629 	ifa_free(&ia->ia_ifa);
1630 	return (error);
1631 }
1632 
1633 static int
1634 carp_del_addr(struct carp_softc *sc, struct sockaddr_in *sin)
1635 {
1636 	int error = 0;
1637 
1638 	if (!--sc->sc_naddrs) {
1639 		struct carp_if *cif = (struct carp_if *)sc->sc_carpdev->if_carp;
1640 		struct ip_moptions *imo = &sc->sc_imo;
1641 
1642 		CARP_LOCK(cif);
1643 		callout_stop(&sc->sc_ad_tmo);
1644 		SC2IFP(sc)->if_flags &= ~IFF_UP;
1645 		SC2IFP(sc)->if_drv_flags &= ~IFF_DRV_RUNNING;
1646 		sc->sc_vhid = -1;
1647 		in_delmulti(imo->imo_membership[--imo->imo_num_memberships]);
1648 		imo->imo_multicast_ifp = NULL;
1649 		TAILQ_REMOVE(&cif->vhif_vrs, sc, sc_list);
1650 		if (!--cif->vhif_nvrs) {
1651 			sc->sc_carpdev->if_carp = NULL;
1652 			CARP_LOCK_DESTROY(cif);
1653 			free(cif, M_CARP);
1654 		} else {
1655 			CARP_UNLOCK(cif);
1656 		}
1657 	}
1658 
1659 	return (error);
1660 }
1661 
1662 #ifdef INET6
1663 static int
1664 carp_set_addr6(struct carp_softc *sc, struct sockaddr_in6 *sin6)
1665 {
1666 	struct ifnet *ifp;
1667 	struct carp_if *cif;
1668 	struct in6_ifaddr *ia, *ia_if;
1669 	struct ip6_moptions *im6o = &sc->sc_im6o;
1670 	struct in6_addr in6;
1671 	int own, error;
1672 
1673 	error = 0;
1674 
1675 	if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr)) {
1676 		if (!(SC2IFP(sc)->if_flags & IFF_UP))
1677 			carp_set_state(sc, INIT);
1678 		if (sc->sc_naddrs6)
1679 			SC2IFP(sc)->if_flags |= IFF_UP;
1680 		if (sc->sc_carpdev)
1681 			CARP_SCLOCK(sc);
1682 		carp_setrun(sc, 0);
1683 		if (sc->sc_carpdev)
1684 			CARP_SCUNLOCK(sc);
1685 		return (0);
1686 	}
1687 
1688 	/* we have to do it by hands to check we won't match on us */
1689 	ia_if = NULL; own = 0;
1690 	IN6_IFADDR_RLOCK();
1691 	TAILQ_FOREACH(ia, &V_in6_ifaddrhead, ia_link) {
1692 		int i;
1693 
1694 		for (i = 0; i < 4; i++) {
1695 			if ((sin6->sin6_addr.s6_addr32[i] &
1696 			    ia->ia_prefixmask.sin6_addr.s6_addr32[i]) !=
1697 			    (ia->ia_addr.sin6_addr.s6_addr32[i] &
1698 			    ia->ia_prefixmask.sin6_addr.s6_addr32[i]))
1699 				break;
1700 		}
1701 		/* and, yeah, we need a multicast-capable iface too */
1702 		if (ia->ia_ifp != SC2IFP(sc) &&
1703 		    (ia->ia_ifp->if_flags & IFF_MULTICAST) &&
1704 		    (i == 4)) {
1705 			if (!ia_if)
1706 				ia_if = ia;
1707 			if (IN6_ARE_ADDR_EQUAL(&sin6->sin6_addr,
1708 			    &ia->ia_addr.sin6_addr))
1709 				own++;
1710 		}
1711 	}
1712 
1713 	if (!ia_if) {
1714 		IN6_IFADDR_RUNLOCK();
1715 		return (EADDRNOTAVAIL);
1716 	}
1717 	ia = ia_if;
1718 	ifa_ref(&ia->ia_ifa);
1719 	IN6_IFADDR_RUNLOCK();
1720 	ifp = ia->ia_ifp;
1721 
1722 	if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0 ||
1723 	    (im6o->im6o_multicast_ifp && im6o->im6o_multicast_ifp != ifp)) {
1724 		ifa_free(&ia->ia_ifa);
1725 		return (EADDRNOTAVAIL);
1726 	}
1727 
1728 	if (!sc->sc_naddrs6) {
1729 		struct in6_multi *in6m;
1730 
1731 		im6o->im6o_multicast_ifp = ifp;
1732 
1733 		/* join CARP multicast address */
1734 		bzero(&in6, sizeof(in6));
1735 		in6.s6_addr16[0] = htons(0xff02);
1736 		in6.s6_addr8[15] = 0x12;
1737 		if (in6_setscope(&in6, ifp, NULL) != 0)
1738 			goto cleanup;
1739 		in6m = NULL;
1740 		error = in6_mc_join(ifp, &in6, NULL, &in6m, 0);
1741 		if (error)
1742 			goto cleanup;
1743 		im6o->im6o_membership[0] = in6m;
1744 		im6o->im6o_num_memberships++;
1745 
1746 		/* join solicited multicast address */
1747 		bzero(&in6, sizeof(in6));
1748 		in6.s6_addr16[0] = htons(0xff02);
1749 		in6.s6_addr32[1] = 0;
1750 		in6.s6_addr32[2] = htonl(1);
1751 		in6.s6_addr32[3] = sin6->sin6_addr.s6_addr32[3];
1752 		in6.s6_addr8[12] = 0xff;
1753 		if (in6_setscope(&in6, ifp, NULL) != 0)
1754 			goto cleanup;
1755 		in6m = NULL;
1756 		error = in6_mc_join(ifp, &in6, NULL, &in6m, 0);
1757 		if (error)
1758 			goto cleanup;
1759 		im6o->im6o_membership[1] = in6m;
1760 		im6o->im6o_num_memberships++;
1761 	}
1762 
1763 	if (!ifp->if_carp) {
1764 		cif = malloc(sizeof(*cif), M_CARP,
1765 		    M_WAITOK|M_ZERO);
1766 		if (!cif) {
1767 			error = ENOBUFS;
1768 			goto cleanup;
1769 		}
1770 		if ((error = ifpromisc(ifp, 1))) {
1771 			free(cif, M_CARP);
1772 			goto cleanup;
1773 		}
1774 
1775 		CARP_LOCK_INIT(cif);
1776 		CARP_LOCK(cif);
1777 		cif->vhif_ifp = ifp;
1778 		TAILQ_INIT(&cif->vhif_vrs);
1779 		ifp->if_carp = cif;
1780 
1781 	} else {
1782 		struct carp_softc *vr;
1783 
1784 		cif = (struct carp_if *)ifp->if_carp;
1785 		CARP_LOCK(cif);
1786 		TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list)
1787 			if (vr != sc && vr->sc_vhid == sc->sc_vhid) {
1788 				CARP_UNLOCK(cif);
1789 				error = EINVAL;
1790 				goto cleanup;
1791 			}
1792 	}
1793 	sc->sc_ia6 = ia;
1794 	sc->sc_carpdev = ifp;
1795 
1796 	{ /* XXX prevent endless loop if already in queue */
1797 	struct carp_softc *vr, *after = NULL;
1798 	int myself = 0;
1799 	cif = (struct carp_if *)ifp->if_carp;
1800 	CARP_LOCK_ASSERT(cif);
1801 
1802 	TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list) {
1803 		if (vr == sc)
1804 			myself = 1;
1805 		if (vr->sc_vhid < sc->sc_vhid)
1806 			after = vr;
1807 	}
1808 
1809 	if (!myself) {
1810 		/* We're trying to keep things in order */
1811 		if (after == NULL) {
1812 			TAILQ_INSERT_TAIL(&cif->vhif_vrs, sc, sc_list);
1813 		} else {
1814 			TAILQ_INSERT_AFTER(&cif->vhif_vrs, after, sc, sc_list);
1815 		}
1816 		cif->vhif_nvrs++;
1817 	}
1818 	}
1819 
1820 	sc->sc_naddrs6++;
1821 	SC2IFP(sc)->if_flags |= IFF_UP;
1822 	if (own)
1823 		sc->sc_advskew = 0;
1824 	carp_sc_state_locked(sc);
1825 	carp_setrun(sc, 0);
1826 
1827 	CARP_UNLOCK(cif);
1828 	ifa_free(&ia->ia_ifa);	/* XXXRW: should hold reference for softc. */
1829 
1830 	return (0);
1831 
1832 cleanup:
1833 	if (!sc->sc_naddrs6)
1834 		carp_multicast6_cleanup(sc);
1835 	ifa_free(&ia->ia_ifa);
1836 	return (error);
1837 }
1838 
1839 static int
1840 carp_del_addr6(struct carp_softc *sc, struct sockaddr_in6 *sin6)
1841 {
1842 	int error = 0;
1843 
1844 	if (!--sc->sc_naddrs6) {
1845 		struct carp_if *cif = (struct carp_if *)sc->sc_carpdev->if_carp;
1846 
1847 		CARP_LOCK(cif);
1848 		callout_stop(&sc->sc_ad_tmo);
1849 		SC2IFP(sc)->if_flags &= ~IFF_UP;
1850 		SC2IFP(sc)->if_drv_flags &= ~IFF_DRV_RUNNING;
1851 		sc->sc_vhid = -1;
1852 		carp_multicast6_cleanup(sc);
1853 		TAILQ_REMOVE(&cif->vhif_vrs, sc, sc_list);
1854 		if (!--cif->vhif_nvrs) {
1855 			CARP_LOCK_DESTROY(cif);
1856 			sc->sc_carpdev->if_carp = NULL;
1857 			free(cif, M_CARP);
1858 		} else
1859 			CARP_UNLOCK(cif);
1860 	}
1861 
1862 	return (error);
1863 }
1864 #endif /* INET6 */
1865 
1866 static int
1867 carp_ioctl(struct ifnet *ifp, u_long cmd, caddr_t addr)
1868 {
1869 	struct carp_softc *sc = ifp->if_softc, *vr;
1870 	struct carpreq carpr;
1871 	struct ifaddr *ifa;
1872 	struct ifreq *ifr;
1873 	struct ifaliasreq *ifra;
1874 	int locked = 0, error = 0;
1875 
1876 	ifa = (struct ifaddr *)addr;
1877 	ifra = (struct ifaliasreq *)addr;
1878 	ifr = (struct ifreq *)addr;
1879 
1880 	switch (cmd) {
1881 	case SIOCSIFADDR:
1882 		switch (ifa->ifa_addr->sa_family) {
1883 #ifdef INET
1884 		case AF_INET:
1885 			SC2IFP(sc)->if_flags |= IFF_UP;
1886 			bcopy(ifa->ifa_addr, ifa->ifa_dstaddr,
1887 			    sizeof(struct sockaddr));
1888 			error = carp_set_addr(sc, satosin(ifa->ifa_addr));
1889 			break;
1890 #endif /* INET */
1891 #ifdef INET6
1892 		case AF_INET6:
1893 			SC2IFP(sc)->if_flags |= IFF_UP;
1894 			error = carp_set_addr6(sc, satosin6(ifa->ifa_addr));
1895 			break;
1896 #endif /* INET6 */
1897 		default:
1898 			error = EAFNOSUPPORT;
1899 			break;
1900 		}
1901 		break;
1902 
1903 	case SIOCAIFADDR:
1904 		switch (ifa->ifa_addr->sa_family) {
1905 #ifdef INET
1906 		case AF_INET:
1907 			SC2IFP(sc)->if_flags |= IFF_UP;
1908 			bcopy(ifa->ifa_addr, ifa->ifa_dstaddr,
1909 			    sizeof(struct sockaddr));
1910 			error = carp_set_addr(sc, satosin(&ifra->ifra_addr));
1911 			break;
1912 #endif /* INET */
1913 #ifdef INET6
1914 		case AF_INET6:
1915 			SC2IFP(sc)->if_flags |= IFF_UP;
1916 			error = carp_set_addr6(sc, satosin6(&ifra->ifra_addr));
1917 			break;
1918 #endif /* INET6 */
1919 		default:
1920 			error = EAFNOSUPPORT;
1921 			break;
1922 		}
1923 		break;
1924 
1925 	case SIOCDIFADDR:
1926 		switch (ifa->ifa_addr->sa_family) {
1927 #ifdef INET
1928 		case AF_INET:
1929 			error = carp_del_addr(sc, satosin(&ifra->ifra_addr));
1930 			break;
1931 #endif /* INET */
1932 #ifdef INET6
1933 		case AF_INET6:
1934 			error = carp_del_addr6(sc, satosin6(&ifra->ifra_addr));
1935 			break;
1936 #endif /* INET6 */
1937 		default:
1938 			error = EAFNOSUPPORT;
1939 			break;
1940 		}
1941 		break;
1942 
1943 	case SIOCSIFFLAGS:
1944 		if (sc->sc_carpdev) {
1945 			locked = 1;
1946 			CARP_SCLOCK(sc);
1947 		}
1948 		if (sc->sc_state != INIT && !(ifr->ifr_flags & IFF_UP)) {
1949  			callout_stop(&sc->sc_ad_tmo);
1950  			callout_stop(&sc->sc_md_tmo);
1951  			callout_stop(&sc->sc_md6_tmo);
1952 			if (sc->sc_state == MASTER)
1953 				carp_send_ad_locked(sc);
1954 			carp_set_state(sc, INIT);
1955 			carp_setrun(sc, 0);
1956 		} else if (sc->sc_state == INIT && (ifr->ifr_flags & IFF_UP)) {
1957 			SC2IFP(sc)->if_flags |= IFF_UP;
1958 			carp_setrun(sc, 0);
1959 		}
1960 		break;
1961 
1962 	case SIOCSVH:
1963 		error = priv_check(curthread, PRIV_NETINET_CARP);
1964 		if (error)
1965 			break;
1966 		if ((error = copyin(ifr->ifr_data, &carpr, sizeof carpr)))
1967 			break;
1968 		error = 1;
1969 		if (sc->sc_carpdev) {
1970 			locked = 1;
1971 			CARP_SCLOCK(sc);
1972 		}
1973 		if (sc->sc_state != INIT && carpr.carpr_state != sc->sc_state) {
1974 			switch (carpr.carpr_state) {
1975 			case BACKUP:
1976 				callout_stop(&sc->sc_ad_tmo);
1977 				carp_set_state(sc, BACKUP);
1978 				carp_setrun(sc, 0);
1979 				carp_setroute(sc, RTM_DELETE);
1980 				break;
1981 			case MASTER:
1982 				carp_master_down_locked(sc);
1983 				break;
1984 			default:
1985 				break;
1986 			}
1987 		}
1988 		if (carpr.carpr_vhid > 0) {
1989 			if (carpr.carpr_vhid > 255) {
1990 				error = EINVAL;
1991 				break;
1992 			}
1993 			if (sc->sc_carpdev) {
1994 				struct carp_if *cif;
1995 				cif = (struct carp_if *)sc->sc_carpdev->if_carp;
1996 				TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list)
1997 					if (vr != sc &&
1998 					    vr->sc_vhid == carpr.carpr_vhid) {
1999 						error = EEXIST;
2000 						break;
2001 					}
2002 				if (error == EEXIST)
2003 					break;
2004 			}
2005 			sc->sc_vhid = carpr.carpr_vhid;
2006 			IF_LLADDR(sc->sc_ifp)[0] = 0;
2007 			IF_LLADDR(sc->sc_ifp)[1] = 0;
2008 			IF_LLADDR(sc->sc_ifp)[2] = 0x5e;
2009 			IF_LLADDR(sc->sc_ifp)[3] = 0;
2010 			IF_LLADDR(sc->sc_ifp)[4] = 1;
2011 			IF_LLADDR(sc->sc_ifp)[5] = sc->sc_vhid;
2012 			error--;
2013 		}
2014 		if (carpr.carpr_advbase > 0 || carpr.carpr_advskew > 0) {
2015 			if (carpr.carpr_advskew >= 255) {
2016 				error = EINVAL;
2017 				break;
2018 			}
2019 			if (carpr.carpr_advbase > 255) {
2020 				error = EINVAL;
2021 				break;
2022 			}
2023 			sc->sc_advbase = carpr.carpr_advbase;
2024 			sc->sc_advskew = carpr.carpr_advskew;
2025 			error--;
2026 		}
2027 		bcopy(carpr.carpr_key, sc->sc_key, sizeof(sc->sc_key));
2028 		if (error > 0)
2029 			error = EINVAL;
2030 		else {
2031 			error = 0;
2032 			carp_setrun(sc, 0);
2033 		}
2034 		break;
2035 
2036 	case SIOCGVH:
2037 		/* XXX: lockless read */
2038 		bzero(&carpr, sizeof(carpr));
2039 		carpr.carpr_state = sc->sc_state;
2040 		carpr.carpr_vhid = sc->sc_vhid;
2041 		carpr.carpr_advbase = sc->sc_advbase;
2042 		carpr.carpr_advskew = sc->sc_advskew;
2043 		error = priv_check(curthread, PRIV_NETINET_CARP);
2044 		if (error == 0)
2045 			bcopy(sc->sc_key, carpr.carpr_key,
2046 			    sizeof(carpr.carpr_key));
2047 		error = copyout(&carpr, ifr->ifr_data, sizeof(carpr));
2048 		break;
2049 
2050 	default:
2051 		error = EINVAL;
2052 	}
2053 
2054 	if (locked)
2055 		CARP_SCUNLOCK(sc);
2056 
2057 	carp_hmac_prepare(sc);
2058 
2059 	return (error);
2060 }
2061 
2062 /*
2063  * XXX: this is looutput. We should eventually use it from there.
2064  */
2065 static int
2066 carp_looutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
2067     struct route *ro)
2068 {
2069 	u_int32_t af;
2070 	struct rtentry *rt = NULL;
2071 
2072 	M_ASSERTPKTHDR(m); /* check if we have the packet header */
2073 
2074 	if (ro != NULL)
2075 		rt = ro->ro_rt;
2076 	if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
2077 		m_freem(m);
2078 		return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
2079 			rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
2080 	}
2081 
2082 	ifp->if_opackets++;
2083 	ifp->if_obytes += m->m_pkthdr.len;
2084 
2085 	/* BPF writes need to be handled specially. */
2086 	if (dst->sa_family == AF_UNSPEC) {
2087 		bcopy(dst->sa_data, &af, sizeof(af));
2088 		dst->sa_family = af;
2089 	}
2090 
2091 #if 1	/* XXX */
2092 	switch (dst->sa_family) {
2093 	case AF_INET:
2094 	case AF_INET6:
2095 	case AF_IPX:
2096 	case AF_APPLETALK:
2097 		break;
2098 	default:
2099 		printf("carp_looutput: af=%d unexpected\n", dst->sa_family);
2100 		m_freem(m);
2101 		return (EAFNOSUPPORT);
2102 	}
2103 #endif
2104 	return(if_simloop(ifp, m, dst->sa_family, 0));
2105 }
2106 
2107 /*
2108  * Start output on carp interface. This function should never be called.
2109  */
2110 static void
2111 carp_start(struct ifnet *ifp)
2112 {
2113 #ifdef DEBUG
2114 	printf("%s: start called\n", ifp->if_xname);
2115 #endif
2116 }
2117 
2118 int
2119 carp_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *sa,
2120     struct rtentry *rt)
2121 {
2122 	struct m_tag *mtag;
2123 	struct carp_softc *sc;
2124 	struct ifnet *carp_ifp;
2125 
2126 	if (!sa)
2127 		return (0);
2128 
2129 	switch (sa->sa_family) {
2130 #ifdef INET
2131 	case AF_INET:
2132 		break;
2133 #endif /* INET */
2134 #ifdef INET6
2135 	case AF_INET6:
2136 		break;
2137 #endif /* INET6 */
2138 	default:
2139 		return (0);
2140 	}
2141 
2142 	mtag = m_tag_find(m, PACKET_TAG_CARP, NULL);
2143 	if (mtag == NULL)
2144 		return (0);
2145 
2146 	bcopy(mtag + 1, &carp_ifp, sizeof(struct ifnet *));
2147 	sc = carp_ifp->if_softc;
2148 
2149 	/* Set the source MAC address to Virtual Router MAC Address */
2150 	switch (ifp->if_type) {
2151 	case IFT_ETHER:
2152 	case IFT_L2VLAN: {
2153 			struct ether_header *eh;
2154 
2155 			eh = mtod(m, struct ether_header *);
2156 			eh->ether_shost[0] = 0;
2157 			eh->ether_shost[1] = 0;
2158 			eh->ether_shost[2] = 0x5e;
2159 			eh->ether_shost[3] = 0;
2160 			eh->ether_shost[4] = 1;
2161 			eh->ether_shost[5] = sc->sc_vhid;
2162 		}
2163 		break;
2164 	case IFT_FDDI: {
2165 			struct fddi_header *fh;
2166 
2167 			fh = mtod(m, struct fddi_header *);
2168 			fh->fddi_shost[0] = 0;
2169 			fh->fddi_shost[1] = 0;
2170 			fh->fddi_shost[2] = 0x5e;
2171 			fh->fddi_shost[3] = 0;
2172 			fh->fddi_shost[4] = 1;
2173 			fh->fddi_shost[5] = sc->sc_vhid;
2174 		}
2175 		break;
2176 	case IFT_ISO88025: {
2177  			struct iso88025_header *th;
2178  			th = mtod(m, struct iso88025_header *);
2179 			th->iso88025_shost[0] = 3;
2180 			th->iso88025_shost[1] = 0;
2181 			th->iso88025_shost[2] = 0x40 >> (sc->sc_vhid - 1);
2182 			th->iso88025_shost[3] = 0x40000 >> (sc->sc_vhid - 1);
2183 			th->iso88025_shost[4] = 0;
2184 			th->iso88025_shost[5] = 0;
2185 		}
2186 		break;
2187 	default:
2188 		printf("%s: carp is not supported for this interface type\n",
2189 		    ifp->if_xname);
2190 		return (EOPNOTSUPP);
2191 	}
2192 
2193 	return (0);
2194 }
2195 
2196 static void
2197 carp_set_state(struct carp_softc *sc, int state)
2198 {
2199 	int link_state;
2200 
2201 	if (sc->sc_carpdev)
2202 		CARP_SCLOCK_ASSERT(sc);
2203 
2204 	if (sc->sc_state == state)
2205 		return;
2206 
2207 	sc->sc_state = state;
2208 	switch (state) {
2209 	case BACKUP:
2210 		link_state = LINK_STATE_DOWN;
2211 		break;
2212 	case MASTER:
2213 		link_state = LINK_STATE_UP;
2214 		break;
2215 	default:
2216 		link_state = LINK_STATE_UNKNOWN;
2217 		break;
2218 	}
2219 	if_link_state_change(SC2IFP(sc), link_state);
2220 }
2221 
2222 void
2223 carp_carpdev_state(struct ifnet *ifp)
2224 {
2225 	struct carp_if *cif;
2226 
2227 	cif = ifp->if_carp;
2228 	CARP_LOCK(cif);
2229 	carp_carpdev_state_locked(cif);
2230 	CARP_UNLOCK(cif);
2231 }
2232 
2233 static void
2234 carp_carpdev_state_locked(struct carp_if *cif)
2235 {
2236 	struct carp_softc *sc;
2237 
2238 	TAILQ_FOREACH(sc, &cif->vhif_vrs, sc_list)
2239 		carp_sc_state_locked(sc);
2240 }
2241 
2242 static void
2243 carp_sc_state_locked(struct carp_softc *sc)
2244 {
2245 	CARP_SCLOCK_ASSERT(sc);
2246 
2247 	if (sc->sc_carpdev->if_link_state != LINK_STATE_UP ||
2248 	    !(sc->sc_carpdev->if_flags & IFF_UP)) {
2249 		sc->sc_flags_backup = SC2IFP(sc)->if_flags;
2250 		SC2IFP(sc)->if_flags &= ~IFF_UP;
2251 		SC2IFP(sc)->if_drv_flags &= ~IFF_DRV_RUNNING;
2252 		callout_stop(&sc->sc_ad_tmo);
2253 		callout_stop(&sc->sc_md_tmo);
2254 		callout_stop(&sc->sc_md6_tmo);
2255 		carp_set_state(sc, INIT);
2256 		carp_setrun(sc, 0);
2257 		if (!sc->sc_suppress) {
2258 			carp_suppress_preempt++;
2259 			if (carp_suppress_preempt == 1) {
2260 				CARP_SCUNLOCK(sc);
2261 				carp_send_ad_all();
2262 				CARP_SCLOCK(sc);
2263 			}
2264 		}
2265 		sc->sc_suppress = 1;
2266 	} else {
2267 		SC2IFP(sc)->if_flags |= sc->sc_flags_backup;
2268 		carp_set_state(sc, INIT);
2269 		carp_setrun(sc, 0);
2270 		if (sc->sc_suppress)
2271 			carp_suppress_preempt--;
2272 		sc->sc_suppress = 0;
2273 	}
2274 
2275 	return;
2276 }
2277 
2278 #ifdef INET
2279 extern  struct domain inetdomain;
2280 static struct protosw in_carp_protosw = {
2281 	.pr_type =		SOCK_RAW,
2282 	.pr_domain =		&inetdomain,
2283 	.pr_protocol =		IPPROTO_CARP,
2284 	.pr_flags =		PR_ATOMIC|PR_ADDR,
2285 	.pr_input =		carp_input,
2286 	.pr_output =		(pr_output_t *)rip_output,
2287 	.pr_ctloutput =		rip_ctloutput,
2288 	.pr_usrreqs =		&rip_usrreqs
2289 };
2290 #endif
2291 
2292 #ifdef INET6
2293 extern	struct domain inet6domain;
2294 static struct ip6protosw in6_carp_protosw = {
2295 	.pr_type =		SOCK_RAW,
2296 	.pr_domain =		&inet6domain,
2297 	.pr_protocol =		IPPROTO_CARP,
2298 	.pr_flags =		PR_ATOMIC|PR_ADDR,
2299 	.pr_input =		carp6_input,
2300 	.pr_output =		rip6_output,
2301 	.pr_ctloutput =		rip6_ctloutput,
2302 	.pr_usrreqs =		&rip6_usrreqs
2303 };
2304 #endif
2305 
2306 static void
2307 carp_mod_cleanup(void)
2308 {
2309 
2310 	if (if_detach_event_tag == NULL)
2311 		return;
2312 	EVENTHANDLER_DEREGISTER(ifnet_departure_event, if_detach_event_tag);
2313 	if_clone_detach(&carp_cloner);
2314 #ifdef INET
2315 	if (proto_reg[CARP_INET] == 0) {
2316 		(void)ipproto_unregister(IPPROTO_CARP);
2317 		pf_proto_unregister(PF_INET, IPPROTO_CARP, SOCK_RAW);
2318 		proto_reg[CARP_INET] = -1;
2319 	}
2320 	carp_iamatch_p = NULL;
2321 #endif
2322 #ifdef INET6
2323 	if (proto_reg[CARP_INET6] == 0) {
2324 		(void)ip6proto_unregister(IPPROTO_CARP);
2325 		pf_proto_unregister(PF_INET6, IPPROTO_CARP, SOCK_RAW);
2326 		proto_reg[CARP_INET6] = -1;
2327 	}
2328 	carp_iamatch6_p = NULL;
2329 	carp_macmatch6_p = NULL;
2330 #endif
2331 	carp_linkstate_p = NULL;
2332 	carp_forus_p = NULL;
2333 	carp_output_p = NULL;
2334 	mtx_destroy(&carp_mtx);
2335 }
2336 
2337 static int
2338 carp_mod_load(void)
2339 {
2340 	int err;
2341 
2342 	if_detach_event_tag = EVENTHANDLER_REGISTER(ifnet_departure_event,
2343 		carp_ifdetach, NULL, EVENTHANDLER_PRI_ANY);
2344 	if (if_detach_event_tag == NULL)
2345 		return (ENOMEM);
2346 	mtx_init(&carp_mtx, "carp_mtx", NULL, MTX_DEF);
2347 	LIST_INIT(&carpif_list);
2348 	if_clone_attach(&carp_cloner);
2349 	carp_linkstate_p = carp_carpdev_state;
2350 	carp_forus_p = carp_forus;
2351 	carp_output_p = carp_output;
2352 #ifdef INET6
2353 	carp_iamatch6_p = carp_iamatch6;
2354 	carp_macmatch6_p = carp_macmatch6;
2355 	proto_reg[CARP_INET6] = pf_proto_register(PF_INET6,
2356 	    (struct protosw *)&in6_carp_protosw);
2357 	if (proto_reg[CARP_INET6] != 0) {
2358 		printf("carp: error %d attaching to PF_INET6\n",
2359 		    proto_reg[CARP_INET6]);
2360 		carp_mod_cleanup();
2361 		return (proto_reg[CARP_INET6]);
2362 	}
2363 	err = ip6proto_register(IPPROTO_CARP);
2364 	if (err) {
2365 		printf("carp: error %d registering with INET6\n", err);
2366 		carp_mod_cleanup();
2367 		return (err);
2368 	}
2369 #endif
2370 #ifdef INET
2371 	carp_iamatch_p = carp_iamatch;
2372 	proto_reg[CARP_INET] = pf_proto_register(PF_INET, &in_carp_protosw);
2373 	if (proto_reg[CARP_INET] != 0) {
2374 		printf("carp: error %d attaching to PF_INET\n",
2375 		    proto_reg[CARP_INET]);
2376 		carp_mod_cleanup();
2377 		return (proto_reg[CARP_INET]);
2378 	}
2379 	err = ipproto_register(IPPROTO_CARP);
2380 	if (err) {
2381 		printf("carp: error %d registering with INET\n", err);
2382 		carp_mod_cleanup();
2383 		return (err);
2384 	}
2385 #endif
2386 	return 0;
2387 }
2388 
2389 static int
2390 carp_modevent(module_t mod, int type, void *data)
2391 {
2392 	switch (type) {
2393 	case MOD_LOAD:
2394 		return carp_mod_load();
2395 		/* NOTREACHED */
2396 	case MOD_UNLOAD:
2397 		/*
2398 		 * XXX: For now, disallow module unloading by default due to
2399 		 * a race condition where a thread may dereference one of the
2400 		 * function pointer hooks after the module has been
2401 		 * unloaded, during processing of a packet, causing a panic.
2402 		 */
2403 #ifdef CARPMOD_CAN_UNLOAD
2404 		carp_mod_cleanup();
2405 #else
2406 		return (EBUSY);
2407 #endif
2408 		break;
2409 
2410 	default:
2411 		return (EINVAL);
2412 	}
2413 
2414 	return (0);
2415 }
2416 
2417 static moduledata_t carp_mod = {
2418 	"carp",
2419 	carp_modevent,
2420 	0
2421 };
2422 
2423 DECLARE_MODULE(carp, carp_mod, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY);
2424