xref: /freebsd/sys/netinet6/in6_src.c (revision eb6d21b4ca6d668cf89afd99eef7baeafa712197)
1 /*-
2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
3  * 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  * 3. Neither the name of the project nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 PROJECT 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  *	$KAME: in6_src.c,v 1.132 2003/08/26 04:42:27 keiichi Exp $
30  */
31 
32 /*-
33  * Copyright (c) 1982, 1986, 1991, 1993
34  *	The Regents of the University of California.  All rights reserved.
35  *
36  * Redistribution and use in source and binary forms, with or without
37  * modification, are permitted provided that the following conditions
38  * are met:
39  * 1. Redistributions of source code must retain the above copyright
40  *    notice, this list of conditions and the following disclaimer.
41  * 2. Redistributions in binary form must reproduce the above copyright
42  *    notice, this list of conditions and the following disclaimer in the
43  *    documentation and/or other materials provided with the distribution.
44  * 4. Neither the name of the University nor the names of its contributors
45  *    may be used to endorse or promote products derived from this software
46  *    without specific prior written permission.
47  *
48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
58  * SUCH DAMAGE.
59  *
60  *	@(#)in_pcb.c	8.2 (Berkeley) 1/4/94
61  */
62 
63 #include <sys/cdefs.h>
64 __FBSDID("$FreeBSD$");
65 
66 #include "opt_inet.h"
67 #include "opt_inet6.h"
68 #include "opt_mpath.h"
69 
70 #include <sys/param.h>
71 #include <sys/systm.h>
72 #include <sys/lock.h>
73 #include <sys/malloc.h>
74 #include <sys/mbuf.h>
75 #include <sys/priv.h>
76 #include <sys/protosw.h>
77 #include <sys/socket.h>
78 #include <sys/socketvar.h>
79 #include <sys/sockio.h>
80 #include <sys/sysctl.h>
81 #include <sys/errno.h>
82 #include <sys/time.h>
83 #include <sys/jail.h>
84 #include <sys/kernel.h>
85 #include <sys/sx.h>
86 
87 #include <net/if.h>
88 #include <net/if_dl.h>
89 #include <net/route.h>
90 #include <net/if_llatbl.h>
91 #ifdef RADIX_MPATH
92 #include <net/radix_mpath.h>
93 #endif
94 
95 #include <netinet/in.h>
96 #include <netinet/in_var.h>
97 #include <netinet/in_systm.h>
98 #include <netinet/ip.h>
99 #include <netinet/in_pcb.h>
100 #include <netinet/ip_var.h>
101 #include <netinet/udp.h>
102 #include <netinet/udp_var.h>
103 
104 #include <netinet6/in6_var.h>
105 #include <netinet/ip6.h>
106 #include <netinet6/in6_pcb.h>
107 #include <netinet6/ip6_var.h>
108 #include <netinet6/scope6_var.h>
109 #include <netinet6/nd6.h>
110 
111 static struct mtx addrsel_lock;
112 #define	ADDRSEL_LOCK_INIT()	mtx_init(&addrsel_lock, "addrsel_lock", NULL, MTX_DEF)
113 #define	ADDRSEL_LOCK()		mtx_lock(&addrsel_lock)
114 #define	ADDRSEL_UNLOCK()	mtx_unlock(&addrsel_lock)
115 #define	ADDRSEL_LOCK_ASSERT()	mtx_assert(&addrsel_lock, MA_OWNED)
116 
117 static struct sx addrsel_sxlock;
118 #define	ADDRSEL_SXLOCK_INIT()	sx_init(&addrsel_sxlock, "addrsel_sxlock")
119 #define	ADDRSEL_SLOCK()		sx_slock(&addrsel_sxlock)
120 #define	ADDRSEL_SUNLOCK()	sx_sunlock(&addrsel_sxlock)
121 #define	ADDRSEL_XLOCK()		sx_xlock(&addrsel_sxlock)
122 #define	ADDRSEL_XUNLOCK()	sx_xunlock(&addrsel_sxlock)
123 
124 #define ADDR_LABEL_NOTAPP (-1)
125 
126 static VNET_DEFINE(struct in6_addrpolicy, defaultaddrpolicy);
127 VNET_DEFINE(int, ip6_prefer_tempaddr);
128 
129 #define	V_defaultaddrpolicy		VNET(defaultaddrpolicy)
130 
131 static int selectroute __P((struct sockaddr_in6 *, struct ip6_pktopts *,
132 	struct ip6_moptions *, struct route_in6 *, struct ifnet **,
133 	struct rtentry **, int));
134 static int in6_selectif __P((struct sockaddr_in6 *, struct ip6_pktopts *,
135 	struct ip6_moptions *, struct route_in6 *ro, struct ifnet **));
136 
137 static struct in6_addrpolicy *lookup_addrsel_policy(struct sockaddr_in6 *);
138 
139 static void init_policy_queue(void);
140 static int add_addrsel_policyent(struct in6_addrpolicy *);
141 static int delete_addrsel_policyent(struct in6_addrpolicy *);
142 static int walk_addrsel_policy __P((int (*)(struct in6_addrpolicy *, void *),
143 				    void *));
144 static int dump_addrsel_policyent(struct in6_addrpolicy *, void *);
145 static struct in6_addrpolicy *match_addrsel_policy(struct sockaddr_in6 *);
146 
147 /*
148  * Return an IPv6 address, which is the most appropriate for a given
149  * destination and user specified options.
150  * If necessary, this function lookups the routing table and returns
151  * an entry to the caller for later use.
152  */
153 #define REPLACE(r) do {\
154 	if ((r) < sizeof(V_ip6stat.ip6s_sources_rule) / \
155 		sizeof(V_ip6stat.ip6s_sources_rule[0])) /* check for safety */ \
156 		V_ip6stat.ip6s_sources_rule[(r)]++; \
157 	/* { \
158 	char ip6buf[INET6_ADDRSTRLEN], ip6b[INET6_ADDRSTRLEN]; \
159 	printf("in6_selectsrc: replace %s with %s by %d\n", ia_best ? ip6_sprintf(ip6buf, &ia_best->ia_addr.sin6_addr) : "none", ip6_sprintf(ip6b, &ia->ia_addr.sin6_addr), (r)); \
160 	} */ \
161 	goto replace; \
162 } while(0)
163 #define NEXT(r) do {\
164 	if ((r) < sizeof(V_ip6stat.ip6s_sources_rule) / \
165 		sizeof(V_ip6stat.ip6s_sources_rule[0])) /* check for safety */ \
166 		V_ip6stat.ip6s_sources_rule[(r)]++; \
167 	/* { \
168 	char ip6buf[INET6_ADDRSTRLEN], ip6b[INET6_ADDRSTRLEN]; \
169 	printf("in6_selectsrc: keep %s against %s by %d\n", ia_best ? ip6_sprintf(ip6buf, &ia_best->ia_addr.sin6_addr) : "none", ip6_sprintf(ip6b, &ia->ia_addr.sin6_addr), (r)); \
170 	} */ \
171 	goto next;		/* XXX: we can't use 'continue' here */ \
172 } while(0)
173 #define BREAK(r) do { \
174 	if ((r) < sizeof(V_ip6stat.ip6s_sources_rule) / \
175 		sizeof(V_ip6stat.ip6s_sources_rule[0])) /* check for safety */ \
176 		V_ip6stat.ip6s_sources_rule[(r)]++; \
177 	goto out;		/* XXX: we can't use 'break' here */ \
178 } while(0)
179 
180 int
181 in6_selectsrc(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
182     struct inpcb *inp, struct route_in6 *ro, struct ucred *cred,
183     struct ifnet **ifpp, struct in6_addr *srcp)
184 {
185 	struct in6_addr dst;
186 	struct ifnet *ifp = NULL;
187 	struct in6_ifaddr *ia = NULL, *ia_best = NULL;
188 	struct in6_pktinfo *pi = NULL;
189 	int dst_scope = -1, best_scope = -1, best_matchlen = -1;
190 	struct in6_addrpolicy *dst_policy = NULL, *best_policy = NULL;
191 	u_int32_t odstzone;
192 	int prefer_tempaddr;
193 	int error;
194 	struct ip6_moptions *mopts;
195 
196 	KASSERT(srcp != NULL, ("%s: srcp is NULL", __func__));
197 
198 	dst = dstsock->sin6_addr; /* make a copy for local operation */
199 	if (ifpp)
200 		*ifpp = NULL;
201 
202 	if (inp != NULL) {
203 		INP_LOCK_ASSERT(inp);
204 		mopts = inp->in6p_moptions;
205 	} else {
206 		mopts = NULL;
207 	}
208 
209 	/*
210 	 * If the source address is explicitly specified by the caller,
211 	 * check if the requested source address is indeed a unicast address
212 	 * assigned to the node, and can be used as the packet's source
213 	 * address.  If everything is okay, use the address as source.
214 	 */
215 	if (opts && (pi = opts->ip6po_pktinfo) &&
216 	    !IN6_IS_ADDR_UNSPECIFIED(&pi->ipi6_addr)) {
217 		struct sockaddr_in6 srcsock;
218 		struct in6_ifaddr *ia6;
219 
220 		/* get the outgoing interface */
221 		if ((error = in6_selectif(dstsock, opts, mopts, ro, &ifp)) != 0)
222 			return (error);
223 
224 		/*
225 		 * determine the appropriate zone id of the source based on
226 		 * the zone of the destination and the outgoing interface.
227 		 * If the specified address is ambiguous wrt the scope zone,
228 		 * the interface must be specified; otherwise, ifa_ifwithaddr()
229 		 * will fail matching the address.
230 		 */
231 		bzero(&srcsock, sizeof(srcsock));
232 		srcsock.sin6_family = AF_INET6;
233 		srcsock.sin6_len = sizeof(srcsock);
234 		srcsock.sin6_addr = pi->ipi6_addr;
235 		if (ifp) {
236 			error = in6_setscope(&srcsock.sin6_addr, ifp, NULL);
237 			if (error)
238 				return (error);
239 		}
240 		if (cred != NULL && (error = prison_local_ip6(cred,
241 		    &srcsock.sin6_addr, (inp != NULL &&
242 		    (inp->inp_flags & IN6P_IPV6_V6ONLY) != 0))) != 0)
243 			return (error);
244 
245 		ia6 = (struct in6_ifaddr *)ifa_ifwithaddr(
246 		    (struct sockaddr *)&srcsock);
247 		if (ia6 == NULL ||
248 		    (ia6->ia6_flags & (IN6_IFF_ANYCAST | IN6_IFF_NOTREADY))) {
249 			if (ia6 != NULL)
250 				ifa_free(&ia6->ia_ifa);
251 			return (EADDRNOTAVAIL);
252 		}
253 		pi->ipi6_addr = srcsock.sin6_addr; /* XXX: this overrides pi */
254 		if (ifpp)
255 			*ifpp = ifp;
256 		bcopy(&ia6->ia_addr.sin6_addr, srcp, sizeof(*srcp));
257 		ifa_free(&ia6->ia_ifa);
258 		return (0);
259 	}
260 
261 	/*
262 	 * Otherwise, if the socket has already bound the source, just use it.
263 	 */
264 	if (inp != NULL && !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) {
265 		if (cred != NULL &&
266 		    (error = prison_local_ip6(cred, &inp->in6p_laddr,
267 		    ((inp->inp_flags & IN6P_IPV6_V6ONLY) != 0))) != 0)
268 			return (error);
269 		bcopy(&inp->in6p_laddr, srcp, sizeof(*srcp));
270 		return (0);
271 	}
272 
273 	/*
274 	 * If the address is not specified, choose the best one based on
275 	 * the outgoing interface and the destination address.
276 	 */
277 	/* get the outgoing interface */
278 	if ((error = in6_selectif(dstsock, opts, mopts, ro, &ifp)) != 0)
279 		return (error);
280 
281 #ifdef DIAGNOSTIC
282 	if (ifp == NULL)	/* this should not happen */
283 		panic("in6_selectsrc: NULL ifp");
284 #endif
285 	error = in6_setscope(&dst, ifp, &odstzone);
286 	if (error)
287 		return (error);
288 
289 	IN6_IFADDR_RLOCK();
290 	TAILQ_FOREACH(ia, &V_in6_ifaddrhead, ia_link) {
291 		int new_scope = -1, new_matchlen = -1;
292 		struct in6_addrpolicy *new_policy = NULL;
293 		u_int32_t srczone, osrczone, dstzone;
294 		struct in6_addr src;
295 		struct ifnet *ifp1 = ia->ia_ifp;
296 
297 		/*
298 		 * We'll never take an address that breaks the scope zone
299 		 * of the destination.  We also skip an address if its zone
300 		 * does not contain the outgoing interface.
301 		 * XXX: we should probably use sin6_scope_id here.
302 		 */
303 		if (in6_setscope(&dst, ifp1, &dstzone) ||
304 		    odstzone != dstzone) {
305 			continue;
306 		}
307 		src = ia->ia_addr.sin6_addr;
308 		if (in6_setscope(&src, ifp, &osrczone) ||
309 		    in6_setscope(&src, ifp1, &srczone) ||
310 		    osrczone != srczone) {
311 			continue;
312 		}
313 
314 		/* avoid unusable addresses */
315 		if ((ia->ia6_flags &
316 		     (IN6_IFF_NOTREADY | IN6_IFF_ANYCAST | IN6_IFF_DETACHED))) {
317 				continue;
318 		}
319 		if (!V_ip6_use_deprecated && IFA6_IS_DEPRECATED(ia))
320 			continue;
321 
322 		if (cred != NULL &&
323 		    prison_local_ip6(cred, &ia->ia_addr.sin6_addr,
324 			(inp != NULL &&
325 			(inp->inp_flags & IN6P_IPV6_V6ONLY) != 0)) != 0)
326 			continue;
327 
328 		/* Rule 1: Prefer same address */
329 		if (IN6_ARE_ADDR_EQUAL(&dst, &ia->ia_addr.sin6_addr)) {
330 			ia_best = ia;
331 			BREAK(1); /* there should be no better candidate */
332 		}
333 
334 		if (ia_best == NULL)
335 			REPLACE(0);
336 
337 		/* Rule 2: Prefer appropriate scope */
338 		if (dst_scope < 0)
339 			dst_scope = in6_addrscope(&dst);
340 		new_scope = in6_addrscope(&ia->ia_addr.sin6_addr);
341 		if (IN6_ARE_SCOPE_CMP(best_scope, new_scope) < 0) {
342 			if (IN6_ARE_SCOPE_CMP(best_scope, dst_scope) < 0)
343 				REPLACE(2);
344 			NEXT(2);
345 		} else if (IN6_ARE_SCOPE_CMP(new_scope, best_scope) < 0) {
346 			if (IN6_ARE_SCOPE_CMP(new_scope, dst_scope) < 0)
347 				NEXT(2);
348 			REPLACE(2);
349 		}
350 
351 		/*
352 		 * Rule 3: Avoid deprecated addresses.  Note that the case of
353 		 * !ip6_use_deprecated is already rejected above.
354 		 */
355 		if (!IFA6_IS_DEPRECATED(ia_best) && IFA6_IS_DEPRECATED(ia))
356 			NEXT(3);
357 		if (IFA6_IS_DEPRECATED(ia_best) && !IFA6_IS_DEPRECATED(ia))
358 			REPLACE(3);
359 
360 		/* Rule 4: Prefer home addresses */
361 		/*
362 		 * XXX: This is a TODO.  We should probably merge the MIP6
363 		 * case above.
364 		 */
365 
366 		/* Rule 5: Prefer outgoing interface */
367 		if (ia_best->ia_ifp == ifp && ia->ia_ifp != ifp)
368 			NEXT(5);
369 		if (ia_best->ia_ifp != ifp && ia->ia_ifp == ifp)
370 			REPLACE(5);
371 
372 		/*
373 		 * Rule 6: Prefer matching label
374 		 * Note that best_policy should be non-NULL here.
375 		 */
376 		if (dst_policy == NULL)
377 			dst_policy = lookup_addrsel_policy(dstsock);
378 		if (dst_policy->label != ADDR_LABEL_NOTAPP) {
379 			new_policy = lookup_addrsel_policy(&ia->ia_addr);
380 			if (dst_policy->label == best_policy->label &&
381 			    dst_policy->label != new_policy->label)
382 				NEXT(6);
383 			if (dst_policy->label != best_policy->label &&
384 			    dst_policy->label == new_policy->label)
385 				REPLACE(6);
386 		}
387 
388 		/*
389 		 * Rule 7: Prefer public addresses.
390 		 * We allow users to reverse the logic by configuring
391 		 * a sysctl variable, so that privacy conscious users can
392 		 * always prefer temporary addresses.
393 		 */
394 		if (opts == NULL ||
395 		    opts->ip6po_prefer_tempaddr == IP6PO_TEMPADDR_SYSTEM) {
396 			prefer_tempaddr = V_ip6_prefer_tempaddr;
397 		} else if (opts->ip6po_prefer_tempaddr ==
398 		    IP6PO_TEMPADDR_NOTPREFER) {
399 			prefer_tempaddr = 0;
400 		} else
401 			prefer_tempaddr = 1;
402 		if (!(ia_best->ia6_flags & IN6_IFF_TEMPORARY) &&
403 		    (ia->ia6_flags & IN6_IFF_TEMPORARY)) {
404 			if (prefer_tempaddr)
405 				REPLACE(7);
406 			else
407 				NEXT(7);
408 		}
409 		if ((ia_best->ia6_flags & IN6_IFF_TEMPORARY) &&
410 		    !(ia->ia6_flags & IN6_IFF_TEMPORARY)) {
411 			if (prefer_tempaddr)
412 				NEXT(7);
413 			else
414 				REPLACE(7);
415 		}
416 
417 		/*
418 		 * Rule 8: prefer addresses on alive interfaces.
419 		 * This is a KAME specific rule.
420 		 */
421 		if ((ia_best->ia_ifp->if_flags & IFF_UP) &&
422 		    !(ia->ia_ifp->if_flags & IFF_UP))
423 			NEXT(8);
424 		if (!(ia_best->ia_ifp->if_flags & IFF_UP) &&
425 		    (ia->ia_ifp->if_flags & IFF_UP))
426 			REPLACE(8);
427 
428 		/*
429 		 * Rule 14: Use longest matching prefix.
430 		 * Note: in the address selection draft, this rule is
431 		 * documented as "Rule 8".  However, since it is also
432 		 * documented that this rule can be overridden, we assign
433 		 * a large number so that it is easy to assign smaller numbers
434 		 * to more preferred rules.
435 		 */
436 		new_matchlen = in6_matchlen(&ia->ia_addr.sin6_addr, &dst);
437 		if (best_matchlen < new_matchlen)
438 			REPLACE(14);
439 		if (new_matchlen < best_matchlen)
440 			NEXT(14);
441 
442 		/* Rule 15 is reserved. */
443 
444 		/*
445 		 * Last resort: just keep the current candidate.
446 		 * Or, do we need more rules?
447 		 */
448 		continue;
449 
450 	  replace:
451 		ia_best = ia;
452 		best_scope = (new_scope >= 0 ? new_scope :
453 			      in6_addrscope(&ia_best->ia_addr.sin6_addr));
454 		best_policy = (new_policy ? new_policy :
455 			       lookup_addrsel_policy(&ia_best->ia_addr));
456 		best_matchlen = (new_matchlen >= 0 ? new_matchlen :
457 				 in6_matchlen(&ia_best->ia_addr.sin6_addr,
458 					      &dst));
459 
460 	  next:
461 		continue;
462 
463 	  out:
464 		break;
465 	}
466 
467 	if ((ia = ia_best) == NULL) {
468 		IN6_IFADDR_RUNLOCK();
469 		return (EADDRNOTAVAIL);
470 	}
471 
472 	if (ifpp)
473 		*ifpp = ifp;
474 
475 	bcopy(&ia->ia_addr.sin6_addr, srcp, sizeof(*srcp));
476 	IN6_IFADDR_RUNLOCK();
477 	return (0);
478 }
479 
480 /*
481  * clone - meaningful only for bsdi and freebsd
482  */
483 static int
484 selectroute(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
485     struct ip6_moptions *mopts, struct route_in6 *ro,
486     struct ifnet **retifp, struct rtentry **retrt, int norouteok)
487 {
488 	int error = 0;
489 	struct ifnet *ifp = NULL;
490 	struct rtentry *rt = NULL;
491 	struct sockaddr_in6 *sin6_next;
492 	struct in6_pktinfo *pi = NULL;
493 	struct in6_addr *dst = &dstsock->sin6_addr;
494 #if 0
495 	char ip6buf[INET6_ADDRSTRLEN];
496 
497 	if (dstsock->sin6_addr.s6_addr32[0] == 0 &&
498 	    dstsock->sin6_addr.s6_addr32[1] == 0 &&
499 	    !IN6_IS_ADDR_LOOPBACK(&dstsock->sin6_addr)) {
500 		printf("in6_selectroute: strange destination %s\n",
501 		       ip6_sprintf(ip6buf, &dstsock->sin6_addr));
502 	} else {
503 		printf("in6_selectroute: destination = %s%%%d\n",
504 		       ip6_sprintf(ip6buf, &dstsock->sin6_addr),
505 		       dstsock->sin6_scope_id); /* for debug */
506 	}
507 #endif
508 
509 	/* If the caller specify the outgoing interface explicitly, use it. */
510 	if (opts && (pi = opts->ip6po_pktinfo) != NULL && pi->ipi6_ifindex) {
511 		/* XXX boundary check is assumed to be already done. */
512 		ifp = ifnet_byindex(pi->ipi6_ifindex);
513 		if (ifp != NULL &&
514 		    (norouteok || retrt == NULL ||
515 		    IN6_IS_ADDR_MULTICAST(dst))) {
516 			/*
517 			 * we do not have to check or get the route for
518 			 * multicast.
519 			 */
520 			goto done;
521 		} else
522 			goto getroute;
523 	}
524 
525 	/*
526 	 * If the destination address is a multicast address and the outgoing
527 	 * interface for the address is specified by the caller, use it.
528 	 */
529 	if (IN6_IS_ADDR_MULTICAST(dst) &&
530 	    mopts != NULL && (ifp = mopts->im6o_multicast_ifp) != NULL) {
531 		goto done; /* we do not need a route for multicast. */
532 	}
533 
534   getroute:
535 	/*
536 	 * If the next hop address for the packet is specified by the caller,
537 	 * use it as the gateway.
538 	 */
539 	if (opts && opts->ip6po_nexthop) {
540 		struct route_in6 *ron;
541 		struct llentry *la;
542 
543 		sin6_next = satosin6(opts->ip6po_nexthop);
544 
545 		/* at this moment, we only support AF_INET6 next hops */
546 		if (sin6_next->sin6_family != AF_INET6) {
547 			error = EAFNOSUPPORT; /* or should we proceed? */
548 			goto done;
549 		}
550 
551 		/*
552 		 * If the next hop is an IPv6 address, then the node identified
553 		 * by that address must be a neighbor of the sending host.
554 		 */
555 		ron = &opts->ip6po_nextroute;
556 		/*
557 		 * XXX what do we do here?
558 		 * PLZ to be fixing
559 		 */
560 
561 
562 		if (ron->ro_rt == NULL) {
563 			rtalloc((struct route *)ron); /* multi path case? */
564 			if (ron->ro_rt == NULL) {
565 				if (ron->ro_rt) {
566 					RTFREE(ron->ro_rt);
567 					ron->ro_rt = NULL;
568 				}
569 				error = EHOSTUNREACH;
570 				goto done;
571 			}
572 		}
573 
574 		rt = ron->ro_rt;
575 		ifp = rt->rt_ifp;
576 		IF_AFDATA_LOCK(ifp);
577 		la = lla_lookup(LLTABLE6(ifp), 0, (struct sockaddr *)&sin6_next->sin6_addr);
578 		IF_AFDATA_UNLOCK(ifp);
579 		if (la != NULL)
580 			LLE_RUNLOCK(la);
581 		else {
582 			error = EHOSTUNREACH;
583 			goto done;
584 		}
585 #if 0
586 		if ((ron->ro_rt &&
587 		     (ron->ro_rt->rt_flags & (RTF_UP | RTF_LLINFO)) !=
588 		     (RTF_UP | RTF_LLINFO)) ||
589 		    !IN6_ARE_ADDR_EQUAL(&satosin6(&ron->ro_dst)->sin6_addr,
590 		    &sin6_next->sin6_addr)) {
591 			if (ron->ro_rt) {
592 				RTFREE(ron->ro_rt);
593 				ron->ro_rt = NULL;
594 			}
595 			*satosin6(&ron->ro_dst) = *sin6_next;
596 		}
597 		if (ron->ro_rt == NULL) {
598 			rtalloc((struct route *)ron); /* multi path case? */
599 			if (ron->ro_rt == NULL ||
600 			    !(ron->ro_rt->rt_flags & RTF_LLINFO)) {
601 				if (ron->ro_rt) {
602 					RTFREE(ron->ro_rt);
603 					ron->ro_rt = NULL;
604 				}
605 				error = EHOSTUNREACH;
606 				goto done;
607 			}
608 		}
609 #endif
610 
611 		/*
612 		 * When cloning is required, try to allocate a route to the
613 		 * destination so that the caller can store path MTU
614 		 * information.
615 		 */
616 		goto done;
617 	}
618 
619 	/*
620 	 * Use a cached route if it exists and is valid, else try to allocate
621 	 * a new one.  Note that we should check the address family of the
622 	 * cached destination, in case of sharing the cache with IPv4.
623 	 */
624 	if (ro) {
625 		if (ro->ro_rt &&
626 		    (!(ro->ro_rt->rt_flags & RTF_UP) ||
627 		     ((struct sockaddr *)(&ro->ro_dst))->sa_family != AF_INET6 ||
628 		     !IN6_ARE_ADDR_EQUAL(&satosin6(&ro->ro_dst)->sin6_addr,
629 		     dst))) {
630 			RTFREE(ro->ro_rt);
631 			ro->ro_rt = (struct rtentry *)NULL;
632 		}
633 		if (ro->ro_rt == (struct rtentry *)NULL) {
634 			struct sockaddr_in6 *sa6;
635 
636 			/* No route yet, so try to acquire one */
637 			bzero(&ro->ro_dst, sizeof(struct sockaddr_in6));
638 			sa6 = (struct sockaddr_in6 *)&ro->ro_dst;
639 			*sa6 = *dstsock;
640 			sa6->sin6_scope_id = 0;
641 
642 #ifdef RADIX_MPATH
643 				rtalloc_mpath((struct route *)ro,
644 				    ntohl(sa6->sin6_addr.s6_addr32[3]));
645 #else
646 				ro->ro_rt = rtalloc1(&((struct route *)ro)
647 				    ->ro_dst, 0, 0UL);
648 				if (ro->ro_rt)
649 					RT_UNLOCK(ro->ro_rt);
650 #endif
651 		}
652 
653 		/*
654 		 * do not care about the result if we have the nexthop
655 		 * explicitly specified.
656 		 */
657 		if (opts && opts->ip6po_nexthop)
658 			goto done;
659 
660 		if (ro->ro_rt) {
661 			ifp = ro->ro_rt->rt_ifp;
662 
663 			if (ifp == NULL) { /* can this really happen? */
664 				RTFREE(ro->ro_rt);
665 				ro->ro_rt = NULL;
666 			}
667 		}
668 		if (ro->ro_rt == NULL)
669 			error = EHOSTUNREACH;
670 		rt = ro->ro_rt;
671 
672 		/*
673 		 * Check if the outgoing interface conflicts with
674 		 * the interface specified by ipi6_ifindex (if specified).
675 		 * Note that loopback interface is always okay.
676 		 * (this may happen when we are sending a packet to one of
677 		 *  our own addresses.)
678 		 */
679 		if (ifp && opts && opts->ip6po_pktinfo &&
680 		    opts->ip6po_pktinfo->ipi6_ifindex) {
681 			if (!(ifp->if_flags & IFF_LOOPBACK) &&
682 			    ifp->if_index !=
683 			    opts->ip6po_pktinfo->ipi6_ifindex) {
684 				error = EHOSTUNREACH;
685 				goto done;
686 			}
687 		}
688 	}
689 
690   done:
691 	if (ifp == NULL && rt == NULL) {
692 		/*
693 		 * This can happen if the caller did not pass a cached route
694 		 * nor any other hints.  We treat this case an error.
695 		 */
696 		error = EHOSTUNREACH;
697 	}
698 	if (error == EHOSTUNREACH)
699 		V_ip6stat.ip6s_noroute++;
700 
701 	if (retifp != NULL) {
702 		*retifp = ifp;
703 
704 		/*
705 		 * Adjust the "outgoing" interface.  If we're going to loop
706 		 * the packet back to ourselves, the ifp would be the loopback
707 		 * interface. However, we'd rather know the interface associated
708 		 * to the destination address (which should probably be one of
709 		 * our own addresses.)
710 		 */
711 		if (rt) {
712 			if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) &&
713 			    (rt->rt_gateway->sa_family == AF_LINK))
714 				*retifp =
715 					ifnet_byindex(((struct sockaddr_dl *)
716 						       rt->rt_gateway)->sdl_index);
717 		}
718 	}
719 
720 	if (retrt != NULL)
721 		*retrt = rt;	/* rt may be NULL */
722 
723 	return (error);
724 }
725 
726 static int
727 in6_selectif(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
728     struct ip6_moptions *mopts, struct route_in6 *ro, struct ifnet **retifp)
729 {
730 	int error;
731 	struct route_in6 sro;
732 	struct rtentry *rt = NULL;
733 
734 	if (ro == NULL) {
735 		bzero(&sro, sizeof(sro));
736 		ro = &sro;
737 	}
738 
739 	if ((error = selectroute(dstsock, opts, mopts, ro, retifp,
740 				     &rt, 1)) != 0) {
741 		if (ro == &sro && rt && rt == sro.ro_rt)
742 			RTFREE(rt);
743 		return (error);
744 	}
745 
746 	/*
747 	 * do not use a rejected or black hole route.
748 	 * XXX: this check should be done in the L2 output routine.
749 	 * However, if we skipped this check here, we'd see the following
750 	 * scenario:
751 	 * - install a rejected route for a scoped address prefix
752 	 *   (like fe80::/10)
753 	 * - send a packet to a destination that matches the scoped prefix,
754 	 *   with ambiguity about the scope zone.
755 	 * - pick the outgoing interface from the route, and disambiguate the
756 	 *   scope zone with the interface.
757 	 * - ip6_output() would try to get another route with the "new"
758 	 *   destination, which may be valid.
759 	 * - we'd see no error on output.
760 	 * Although this may not be very harmful, it should still be confusing.
761 	 * We thus reject the case here.
762 	 */
763 	if (rt && (rt->rt_flags & (RTF_REJECT | RTF_BLACKHOLE))) {
764 		int flags = (rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
765 
766 		if (ro == &sro && rt && rt == sro.ro_rt)
767 			RTFREE(rt);
768 		return (flags);
769 	}
770 
771 	if (ro == &sro && rt && rt == sro.ro_rt)
772 		RTFREE(rt);
773 	return (0);
774 }
775 
776 /*
777  * clone - meaningful only for bsdi and freebsd
778  */
779 int
780 in6_selectroute(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
781     struct ip6_moptions *mopts, struct route_in6 *ro,
782     struct ifnet **retifp, struct rtentry **retrt)
783 {
784 
785 	return (selectroute(dstsock, opts, mopts, ro, retifp,
786 	    retrt, 0));
787 }
788 
789 /*
790  * Default hop limit selection. The precedence is as follows:
791  * 1. Hoplimit value specified via ioctl.
792  * 2. (If the outgoing interface is detected) the current
793  *     hop limit of the interface specified by router advertisement.
794  * 3. The system default hoplimit.
795  */
796 int
797 in6_selecthlim(struct inpcb *in6p, struct ifnet *ifp)
798 {
799 
800 	if (in6p && in6p->in6p_hops >= 0)
801 		return (in6p->in6p_hops);
802 	else if (ifp)
803 		return (ND_IFINFO(ifp)->chlim);
804 	else if (in6p && !IN6_IS_ADDR_UNSPECIFIED(&in6p->in6p_faddr)) {
805 		struct route_in6 ro6;
806 		struct ifnet *lifp;
807 
808 		bzero(&ro6, sizeof(ro6));
809 		ro6.ro_dst.sin6_family = AF_INET6;
810 		ro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6);
811 		ro6.ro_dst.sin6_addr = in6p->in6p_faddr;
812 		rtalloc((struct route *)&ro6);
813 		if (ro6.ro_rt) {
814 			lifp = ro6.ro_rt->rt_ifp;
815 			RTFREE(ro6.ro_rt);
816 			if (lifp)
817 				return (ND_IFINFO(lifp)->chlim);
818 		} else
819 			return (V_ip6_defhlim);
820 	}
821 	return (V_ip6_defhlim);
822 }
823 
824 /*
825  * XXX: this is borrowed from in6_pcbbind(). If possible, we should
826  * share this function by all *bsd*...
827  */
828 int
829 in6_pcbsetport(struct in6_addr *laddr, struct inpcb *inp, struct ucred *cred)
830 {
831 	struct socket *so = inp->inp_socket;
832 	u_int16_t lport = 0, first, last, *lastport;
833 	int count, error, wild = 0, dorandom;
834 	struct inpcbinfo *pcbinfo = inp->inp_pcbinfo;
835 
836 	INP_INFO_WLOCK_ASSERT(pcbinfo);
837 	INP_WLOCK_ASSERT(inp);
838 
839 	error = prison_local_ip6(cred, laddr,
840 	    ((inp->inp_flags & IN6P_IPV6_V6ONLY) != 0));
841 	if (error)
842 		return(error);
843 
844 	/* XXX: this is redundant when called from in6_pcbbind */
845 	if ((so->so_options & (SO_REUSEADDR|SO_REUSEPORT)) == 0)
846 		wild = INPLOOKUP_WILDCARD;
847 
848 	inp->inp_flags |= INP_ANONPORT;
849 
850 	if (inp->inp_flags & INP_HIGHPORT) {
851 		first = V_ipport_hifirstauto;	/* sysctl */
852 		last  = V_ipport_hilastauto;
853 		lastport = &pcbinfo->ipi_lasthi;
854 	} else if (inp->inp_flags & INP_LOWPORT) {
855 		error = priv_check_cred(cred, PRIV_NETINET_RESERVEDPORT, 0);
856 		if (error)
857 			return error;
858 		first = V_ipport_lowfirstauto;	/* 1023 */
859 		last  = V_ipport_lowlastauto;	/* 600 */
860 		lastport = &pcbinfo->ipi_lastlow;
861 	} else {
862 		first = V_ipport_firstauto;	/* sysctl */
863 		last  = V_ipport_lastauto;
864 		lastport = &pcbinfo->ipi_lastport;
865 	}
866 
867 	/*
868 	 * For UDP, use random port allocation as long as the user
869 	 * allows it.  For TCP (and as of yet unknown) connections,
870 	 * use random port allocation only if the user allows it AND
871 	 * ipport_tick() allows it.
872 	 */
873 	if (V_ipport_randomized &&
874 	    (!V_ipport_stoprandom || pcbinfo == &V_udbinfo))
875 		dorandom = 1;
876 	else
877 		dorandom = 0;
878 	/*
879 	 * It makes no sense to do random port allocation if
880 	 * we have the only port available.
881 	 */
882 	if (first == last)
883 		dorandom = 0;
884 	/* Make sure to not include UDP packets in the count. */
885 	if (pcbinfo != &V_udbinfo)
886 		V_ipport_tcpallocs++;
887 
888 	/*
889 	 * Instead of having two loops further down counting up or down
890 	 * make sure that first is always <= last and go with only one
891 	 * code path implementing all logic.
892 	 */
893 	if (first > last) {
894 		u_int16_t aux;
895 
896 		aux = first;
897 		first = last;
898 		last = aux;
899 	}
900 
901 	if (dorandom)
902 		*lastport = first + (arc4random() % (last - first));
903 
904 	count = last - first;
905 
906 	do {
907 		if (count-- < 0) {	/* completely used? */
908 			/* Undo an address bind that may have occurred. */
909 			inp->in6p_laddr = in6addr_any;
910 			return (EADDRNOTAVAIL);
911 		}
912 		++*lastport;
913 		if (*lastport < first || *lastport > last)
914 			*lastport = first;
915 		lport = htons(*lastport);
916 	} while (in6_pcblookup_local(pcbinfo, &inp->in6p_laddr,
917 	    lport, wild, cred));
918 
919 	inp->inp_lport = lport;
920 	if (in_pcbinshash(inp) != 0) {
921 		inp->in6p_laddr = in6addr_any;
922 		inp->inp_lport = 0;
923 		return (EAGAIN);
924 	}
925 
926 	return (0);
927 }
928 
929 void
930 addrsel_policy_init(void)
931 {
932 
933 	V_ip6_prefer_tempaddr = 0;
934 
935 	init_policy_queue();
936 
937 	/* initialize the "last resort" policy */
938 	bzero(&V_defaultaddrpolicy, sizeof(V_defaultaddrpolicy));
939 	V_defaultaddrpolicy.label = ADDR_LABEL_NOTAPP;
940 
941 	if (!IS_DEFAULT_VNET(curvnet))
942 		return;
943 
944 	ADDRSEL_LOCK_INIT();
945 	ADDRSEL_SXLOCK_INIT();
946 }
947 
948 static struct in6_addrpolicy *
949 lookup_addrsel_policy(struct sockaddr_in6 *key)
950 {
951 	struct in6_addrpolicy *match = NULL;
952 
953 	ADDRSEL_LOCK();
954 	match = match_addrsel_policy(key);
955 
956 	if (match == NULL)
957 		match = &V_defaultaddrpolicy;
958 	else
959 		match->use++;
960 	ADDRSEL_UNLOCK();
961 
962 	return (match);
963 }
964 
965 /*
966  * Subroutines to manage the address selection policy table via sysctl.
967  */
968 struct walkarg {
969 	struct sysctl_req *w_req;
970 };
971 
972 static int in6_src_sysctl(SYSCTL_HANDLER_ARGS);
973 SYSCTL_DECL(_net_inet6_ip6);
974 SYSCTL_NODE(_net_inet6_ip6, IPV6CTL_ADDRCTLPOLICY, addrctlpolicy,
975 	CTLFLAG_RD, in6_src_sysctl, "");
976 
977 static int
978 in6_src_sysctl(SYSCTL_HANDLER_ARGS)
979 {
980 	struct walkarg w;
981 
982 	if (req->newptr)
983 		return EPERM;
984 
985 	bzero(&w, sizeof(w));
986 	w.w_req = req;
987 
988 	return (walk_addrsel_policy(dump_addrsel_policyent, &w));
989 }
990 
991 int
992 in6_src_ioctl(u_long cmd, caddr_t data)
993 {
994 	int i;
995 	struct in6_addrpolicy ent0;
996 
997 	if (cmd != SIOCAADDRCTL_POLICY && cmd != SIOCDADDRCTL_POLICY)
998 		return (EOPNOTSUPP); /* check for safety */
999 
1000 	ent0 = *(struct in6_addrpolicy *)data;
1001 
1002 	if (ent0.label == ADDR_LABEL_NOTAPP)
1003 		return (EINVAL);
1004 	/* check if the prefix mask is consecutive. */
1005 	if (in6_mask2len(&ent0.addrmask.sin6_addr, NULL) < 0)
1006 		return (EINVAL);
1007 	/* clear trailing garbages (if any) of the prefix address. */
1008 	for (i = 0; i < 4; i++) {
1009 		ent0.addr.sin6_addr.s6_addr32[i] &=
1010 			ent0.addrmask.sin6_addr.s6_addr32[i];
1011 	}
1012 	ent0.use = 0;
1013 
1014 	switch (cmd) {
1015 	case SIOCAADDRCTL_POLICY:
1016 		return (add_addrsel_policyent(&ent0));
1017 	case SIOCDADDRCTL_POLICY:
1018 		return (delete_addrsel_policyent(&ent0));
1019 	}
1020 
1021 	return (0);		/* XXX: compromise compilers */
1022 }
1023 
1024 /*
1025  * The followings are implementation of the policy table using a
1026  * simple tail queue.
1027  * XXX such details should be hidden.
1028  * XXX implementation using binary tree should be more efficient.
1029  */
1030 struct addrsel_policyent {
1031 	TAILQ_ENTRY(addrsel_policyent) ape_entry;
1032 	struct in6_addrpolicy ape_policy;
1033 };
1034 
1035 TAILQ_HEAD(addrsel_policyhead, addrsel_policyent);
1036 
1037 static VNET_DEFINE(struct addrsel_policyhead, addrsel_policytab);
1038 #define	V_addrsel_policytab		VNET(addrsel_policytab)
1039 
1040 static void
1041 init_policy_queue(void)
1042 {
1043 
1044 	TAILQ_INIT(&V_addrsel_policytab);
1045 }
1046 
1047 static int
1048 add_addrsel_policyent(struct in6_addrpolicy *newpolicy)
1049 {
1050 	struct addrsel_policyent *new, *pol;
1051 
1052 	new = malloc(sizeof(*new), M_IFADDR,
1053 	       M_WAITOK);
1054 	ADDRSEL_XLOCK();
1055 	ADDRSEL_LOCK();
1056 
1057 	/* duplication check */
1058 	TAILQ_FOREACH(pol, &V_addrsel_policytab, ape_entry) {
1059 		if (IN6_ARE_ADDR_EQUAL(&newpolicy->addr.sin6_addr,
1060 				       &pol->ape_policy.addr.sin6_addr) &&
1061 		    IN6_ARE_ADDR_EQUAL(&newpolicy->addrmask.sin6_addr,
1062 				       &pol->ape_policy.addrmask.sin6_addr)) {
1063 			ADDRSEL_UNLOCK();
1064 			ADDRSEL_XUNLOCK();
1065 			free(new, M_IFADDR);
1066 			return (EEXIST);	/* or override it? */
1067 		}
1068 	}
1069 
1070 	bzero(new, sizeof(*new));
1071 
1072 	/* XXX: should validate entry */
1073 	new->ape_policy = *newpolicy;
1074 
1075 	TAILQ_INSERT_TAIL(&V_addrsel_policytab, new, ape_entry);
1076 	ADDRSEL_UNLOCK();
1077 	ADDRSEL_XUNLOCK();
1078 
1079 	return (0);
1080 }
1081 
1082 static int
1083 delete_addrsel_policyent(struct in6_addrpolicy *key)
1084 {
1085 	struct addrsel_policyent *pol;
1086 
1087 	ADDRSEL_XLOCK();
1088 	ADDRSEL_LOCK();
1089 
1090 	/* search for the entry in the table */
1091 	TAILQ_FOREACH(pol, &V_addrsel_policytab, ape_entry) {
1092 		if (IN6_ARE_ADDR_EQUAL(&key->addr.sin6_addr,
1093 		    &pol->ape_policy.addr.sin6_addr) &&
1094 		    IN6_ARE_ADDR_EQUAL(&key->addrmask.sin6_addr,
1095 		    &pol->ape_policy.addrmask.sin6_addr)) {
1096 			break;
1097 		}
1098 	}
1099 	if (pol == NULL) {
1100 		ADDRSEL_UNLOCK();
1101 		ADDRSEL_XUNLOCK();
1102 		return (ESRCH);
1103 	}
1104 
1105 	TAILQ_REMOVE(&V_addrsel_policytab, pol, ape_entry);
1106 	ADDRSEL_UNLOCK();
1107 	ADDRSEL_XUNLOCK();
1108 
1109 	return (0);
1110 }
1111 
1112 static int
1113 walk_addrsel_policy(int (*callback)(struct in6_addrpolicy *, void *),
1114     void *w)
1115 {
1116 	struct addrsel_policyent *pol;
1117 	int error = 0;
1118 
1119 	ADDRSEL_SLOCK();
1120 	TAILQ_FOREACH(pol, &V_addrsel_policytab, ape_entry) {
1121 		if ((error = (*callback)(&pol->ape_policy, w)) != 0) {
1122 			ADDRSEL_SUNLOCK();
1123 			return (error);
1124 		}
1125 	}
1126 	ADDRSEL_SUNLOCK();
1127 	return (error);
1128 }
1129 
1130 static int
1131 dump_addrsel_policyent(struct in6_addrpolicy *pol, void *arg)
1132 {
1133 	int error = 0;
1134 	struct walkarg *w = arg;
1135 
1136 	error = SYSCTL_OUT(w->w_req, pol, sizeof(*pol));
1137 
1138 	return (error);
1139 }
1140 
1141 static struct in6_addrpolicy *
1142 match_addrsel_policy(struct sockaddr_in6 *key)
1143 {
1144 	struct addrsel_policyent *pent;
1145 	struct in6_addrpolicy *bestpol = NULL, *pol;
1146 	int matchlen, bestmatchlen = -1;
1147 	u_char *mp, *ep, *k, *p, m;
1148 
1149 	TAILQ_FOREACH(pent, &V_addrsel_policytab, ape_entry) {
1150 		matchlen = 0;
1151 
1152 		pol = &pent->ape_policy;
1153 		mp = (u_char *)&pol->addrmask.sin6_addr;
1154 		ep = mp + 16;	/* XXX: scope field? */
1155 		k = (u_char *)&key->sin6_addr;
1156 		p = (u_char *)&pol->addr.sin6_addr;
1157 		for (; mp < ep && *mp; mp++, k++, p++) {
1158 			m = *mp;
1159 			if ((*k & m) != *p)
1160 				goto next; /* not match */
1161 			if (m == 0xff) /* short cut for a typical case */
1162 				matchlen += 8;
1163 			else {
1164 				while (m >= 0x80) {
1165 					matchlen++;
1166 					m <<= 1;
1167 				}
1168 			}
1169 		}
1170 
1171 		/* matched.  check if this is better than the current best. */
1172 		if (bestpol == NULL ||
1173 		    matchlen > bestmatchlen) {
1174 			bestpol = pol;
1175 			bestmatchlen = matchlen;
1176 		}
1177 
1178 	  next:
1179 		continue;
1180 	}
1181 
1182 	return (bestpol);
1183 }
1184