1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the project nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 *	$KAME: in6_src.c,v 1.132 2003/08/26 04:42:27 keiichi Exp $
32 */
33
34/*-
35 * Copyright (c) 1982, 1986, 1991, 1993
36 *	The Regents of the University of California.  All rights reserved.
37 *
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
40 * are met:
41 * 1. Redistributions of source code must retain the above copyright
42 *    notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 *    notice, this list of conditions and the following disclaimer in the
45 *    documentation and/or other materials provided with the distribution.
46 * 3. Neither the name of the University nor the names of its contributors
47 *    may be used to endorse or promote products derived from this software
48 *    without specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
60 * SUCH DAMAGE.
61 *
62 *	@(#)in_pcb.c	8.2 (Berkeley) 1/4/94
63 */
64
65#include <sys/cdefs.h>
66__FBSDID("$FreeBSD$");
67
68#include "opt_inet.h"
69#include "opt_inet6.h"
70#include "opt_mpath.h"
71
72#include <sys/param.h>
73#include <sys/systm.h>
74#include <sys/lock.h>
75#include <sys/malloc.h>
76#include <sys/mbuf.h>
77#include <sys/priv.h>
78#include <sys/protosw.h>
79#include <sys/socket.h>
80#include <sys/socketvar.h>
81#include <sys/sockio.h>
82#include <sys/sysctl.h>
83#include <sys/errno.h>
84#include <sys/time.h>
85#include <sys/jail.h>
86#include <sys/kernel.h>
87#include <sys/rmlock.h>
88#include <sys/sx.h>
89
90#include <net/if.h>
91#include <net/if_var.h>
92#include <net/if_dl.h>
93#include <net/route.h>
94#include <net/if_llatbl.h>
95#ifdef RADIX_MPATH
96#include <net/radix_mpath.h>
97#endif
98
99#include <netinet/in.h>
100#include <netinet/in_var.h>
101#include <netinet/in_systm.h>
102#include <netinet/ip.h>
103#include <netinet/in_pcb.h>
104#include <netinet/ip_var.h>
105#include <netinet/udp.h>
106#include <netinet/udp_var.h>
107
108#include <netinet6/in6_var.h>
109#include <netinet/ip6.h>
110#include <netinet6/in6_fib.h>
111#include <netinet6/in6_pcb.h>
112#include <netinet6/ip6_var.h>
113#include <netinet6/scope6_var.h>
114#include <netinet6/nd6.h>
115
116static struct mtx addrsel_lock;
117#define	ADDRSEL_LOCK_INIT()	mtx_init(&addrsel_lock, "addrsel_lock", NULL, MTX_DEF)
118#define	ADDRSEL_LOCK()		mtx_lock(&addrsel_lock)
119#define	ADDRSEL_UNLOCK()	mtx_unlock(&addrsel_lock)
120#define	ADDRSEL_LOCK_ASSERT()	mtx_assert(&addrsel_lock, MA_OWNED)
121
122static struct sx addrsel_sxlock;
123#define	ADDRSEL_SXLOCK_INIT()	sx_init(&addrsel_sxlock, "addrsel_sxlock")
124#define	ADDRSEL_SLOCK()		sx_slock(&addrsel_sxlock)
125#define	ADDRSEL_SUNLOCK()	sx_sunlock(&addrsel_sxlock)
126#define	ADDRSEL_XLOCK()		sx_xlock(&addrsel_sxlock)
127#define	ADDRSEL_XUNLOCK()	sx_xunlock(&addrsel_sxlock)
128
129#define ADDR_LABEL_NOTAPP (-1)
130VNET_DEFINE_STATIC(struct in6_addrpolicy, defaultaddrpolicy);
131#define	V_defaultaddrpolicy		VNET(defaultaddrpolicy)
132
133VNET_DEFINE(int, ip6_prefer_tempaddr) = 0;
134
135static int selectroute(struct sockaddr_in6 *, struct ip6_pktopts *,
136	struct ip6_moptions *, struct route_in6 *, struct ifnet **,
137	struct rtentry **, int, u_int);
138static int in6_selectif(struct sockaddr_in6 *, struct ip6_pktopts *,
139	struct ip6_moptions *, struct ifnet **,
140	struct ifnet *, u_int);
141static int in6_selectsrc(uint32_t, struct sockaddr_in6 *,
142	struct ip6_pktopts *, struct inpcb *, struct ucred *,
143	struct ifnet **, struct in6_addr *);
144
145static struct in6_addrpolicy *lookup_addrsel_policy(struct sockaddr_in6 *);
146
147static void init_policy_queue(void);
148static int add_addrsel_policyent(struct in6_addrpolicy *);
149static int delete_addrsel_policyent(struct in6_addrpolicy *);
150static int walk_addrsel_policy(int (*)(struct in6_addrpolicy *, void *),
151	void *);
152static int dump_addrsel_policyent(struct in6_addrpolicy *, void *);
153static struct in6_addrpolicy *match_addrsel_policy(struct sockaddr_in6 *);
154
155/*
156 * Return an IPv6 address, which is the most appropriate for a given
157 * destination and user specified options.
158 * If necessary, this function lookups the routing table and returns
159 * an entry to the caller for later use.
160 */
161#define REPLACE(r) do {\
162	IP6STAT_INC(ip6s_sources_rule[(r)]); \
163	/* { \
164	char ip6buf[INET6_ADDRSTRLEN], ip6b[INET6_ADDRSTRLEN]; \
165	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)); \
166	} */ \
167	goto replace; \
168} while(0)
169#define NEXT(r) do {\
170	/* { \
171	char ip6buf[INET6_ADDRSTRLEN], ip6b[INET6_ADDRSTRLEN]; \
172	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)); \
173	} */ \
174	goto next;		/* XXX: we can't use 'continue' here */ \
175} while(0)
176#define BREAK(r) do { \
177	IP6STAT_INC(ip6s_sources_rule[(r)]); \
178	goto out;		/* XXX: we can't use 'break' here */ \
179} while(0)
180
181static int
182in6_selectsrc(uint32_t fibnum, struct sockaddr_in6 *dstsock,
183    struct ip6_pktopts *opts, struct inpcb *inp, struct ucred *cred,
184    struct ifnet **ifpp, struct in6_addr *srcp)
185{
186	struct rm_priotracker in6_ifa_tracker;
187	struct in6_addr dst, tmp;
188	struct ifnet *ifp = NULL, *oifp = NULL;
189	struct in6_ifaddr *ia = NULL, *ia_best = NULL;
190	struct in6_pktinfo *pi = NULL;
191	int dst_scope = -1, best_scope = -1, best_matchlen = -1;
192	struct in6_addrpolicy *dst_policy = NULL, *best_policy = NULL;
193	u_int32_t odstzone;
194	int prefer_tempaddr;
195	int error;
196	struct ip6_moptions *mopts;
197
198	KASSERT(srcp != NULL, ("%s: srcp is NULL", __func__));
199
200	dst = dstsock->sin6_addr; /* make a copy for local operation */
201	if (ifpp) {
202		/*
203		 * Save a possibly passed in ifp for in6_selectsrc. Only
204		 * neighbor discovery code should use this feature, where
205		 * we may know the interface but not the FIB number holding
206		 * the connected subnet in case someone deleted it from the
207		 * default FIB and we need to check the interface.
208		 */
209		if (*ifpp != NULL)
210			oifp = *ifpp;
211		*ifpp = NULL;
212	}
213
214	if (inp != NULL) {
215		INP_LOCK_ASSERT(inp);
216		mopts = inp->in6p_moptions;
217	} else {
218		mopts = NULL;
219	}
220
221	/*
222	 * If the source address is explicitly specified by the caller,
223	 * check if the requested source address is indeed a unicast address
224	 * assigned to the node, and can be used as the packet's source
225	 * address.  If everything is okay, use the address as source.
226	 */
227	if (opts && (pi = opts->ip6po_pktinfo) &&
228	    !IN6_IS_ADDR_UNSPECIFIED(&pi->ipi6_addr)) {
229		/* get the outgoing interface */
230		if ((error = in6_selectif(dstsock, opts, mopts, &ifp, oifp,
231		    fibnum))
232		    != 0)
233			return (error);
234
235		/*
236		 * determine the appropriate zone id of the source based on
237		 * the zone of the destination and the outgoing interface.
238		 * If the specified address is ambiguous wrt the scope zone,
239		 * the interface must be specified; otherwise, ifa_ifwithaddr()
240		 * will fail matching the address.
241		 */
242		tmp = pi->ipi6_addr;
243		if (ifp) {
244			error = in6_setscope(&tmp, ifp, &odstzone);
245			if (error)
246				return (error);
247		}
248		if (cred != NULL && (error = prison_local_ip6(cred,
249		    &tmp, (inp->inp_flags & IN6P_IPV6_V6ONLY) != 0)) != 0)
250			return (error);
251
252		/*
253		 * If IPV6_BINDANY socket option is set, we allow to specify
254		 * non local addresses as source address in IPV6_PKTINFO
255		 * ancillary data.
256		 */
257		if ((inp->inp_flags & INP_BINDANY) == 0) {
258			ia = in6ifa_ifwithaddr(&tmp, 0 /* XXX */);
259			if (ia == NULL || (ia->ia6_flags & (IN6_IFF_ANYCAST |
260			    IN6_IFF_NOTREADY))) {
261				if (ia != NULL)
262					ifa_free(&ia->ia_ifa);
263				return (EADDRNOTAVAIL);
264			}
265			bcopy(&ia->ia_addr.sin6_addr, srcp, sizeof(*srcp));
266			ifa_free(&ia->ia_ifa);
267		} else
268			bcopy(&tmp, srcp, sizeof(*srcp));
269		pi->ipi6_addr = tmp; /* XXX: this overrides pi */
270		if (ifpp)
271			*ifpp = ifp;
272		return (0);
273	}
274
275	/*
276	 * Otherwise, if the socket has already bound the source, just use it.
277	 */
278	if (inp != NULL && !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) {
279		if (cred != NULL &&
280		    (error = prison_local_ip6(cred, &inp->in6p_laddr,
281		    ((inp->inp_flags & IN6P_IPV6_V6ONLY) != 0))) != 0)
282			return (error);
283		bcopy(&inp->in6p_laddr, srcp, sizeof(*srcp));
284		return (0);
285	}
286
287	/*
288	 * Bypass source address selection and use the primary jail IP
289	 * if requested.
290	 */
291	if (cred != NULL && !prison_saddrsel_ip6(cred, srcp))
292		return (0);
293
294	/*
295	 * If the address is not specified, choose the best one based on
296	 * the outgoing interface and the destination address.
297	 */
298	/* get the outgoing interface */
299	if ((error = in6_selectif(dstsock, opts, mopts, &ifp, oifp,
300	    (inp != NULL) ? inp->inp_inc.inc_fibnum : fibnum)) != 0)
301		return (error);
302
303#ifdef DIAGNOSTIC
304	if (ifp == NULL)	/* this should not happen */
305		panic("in6_selectsrc: NULL ifp");
306#endif
307	error = in6_setscope(&dst, ifp, &odstzone);
308	if (error)
309		return (error);
310
311	IN6_IFADDR_RLOCK(&in6_ifa_tracker);
312	CK_STAILQ_FOREACH(ia, &V_in6_ifaddrhead, ia_link) {
313		int new_scope = -1, new_matchlen = -1;
314		struct in6_addrpolicy *new_policy = NULL;
315		u_int32_t srczone, osrczone, dstzone;
316		struct in6_addr src;
317		struct ifnet *ifp1 = ia->ia_ifp;
318
319		/*
320		 * We'll never take an address that breaks the scope zone
321		 * of the destination.  We also skip an address if its zone
322		 * does not contain the outgoing interface.
323		 * XXX: we should probably use sin6_scope_id here.
324		 */
325		if (in6_setscope(&dst, ifp1, &dstzone) ||
326		    odstzone != dstzone) {
327			continue;
328		}
329		src = ia->ia_addr.sin6_addr;
330		if (in6_setscope(&src, ifp, &osrczone) ||
331		    in6_setscope(&src, ifp1, &srczone) ||
332		    osrczone != srczone) {
333			continue;
334		}
335
336		/* avoid unusable addresses */
337		if ((ia->ia6_flags &
338		     (IN6_IFF_NOTREADY | IN6_IFF_ANYCAST | IN6_IFF_DETACHED))) {
339				continue;
340		}
341		if (!V_ip6_use_deprecated && IFA6_IS_DEPRECATED(ia))
342			continue;
343
344		/* If jailed only take addresses of the jail into account. */
345		if (cred != NULL &&
346		    prison_check_ip6(cred, &ia->ia_addr.sin6_addr) != 0)
347			continue;
348
349		/* Rule 1: Prefer same address */
350		if (IN6_ARE_ADDR_EQUAL(&dst, &ia->ia_addr.sin6_addr)) {
351			ia_best = ia;
352			BREAK(1); /* there should be no better candidate */
353		}
354
355		if (ia_best == NULL)
356			REPLACE(0);
357
358		/* Rule 2: Prefer appropriate scope */
359		if (dst_scope < 0)
360			dst_scope = in6_addrscope(&dst);
361		new_scope = in6_addrscope(&ia->ia_addr.sin6_addr);
362		if (IN6_ARE_SCOPE_CMP(best_scope, new_scope) < 0) {
363			if (IN6_ARE_SCOPE_CMP(best_scope, dst_scope) < 0)
364				REPLACE(2);
365			NEXT(2);
366		} else if (IN6_ARE_SCOPE_CMP(new_scope, best_scope) < 0) {
367			if (IN6_ARE_SCOPE_CMP(new_scope, dst_scope) < 0)
368				NEXT(2);
369			REPLACE(2);
370		}
371
372		/*
373		 * Rule 3: Avoid deprecated addresses.  Note that the case of
374		 * !ip6_use_deprecated is already rejected above.
375		 */
376		if (!IFA6_IS_DEPRECATED(ia_best) && IFA6_IS_DEPRECATED(ia))
377			NEXT(3);
378		if (IFA6_IS_DEPRECATED(ia_best) && !IFA6_IS_DEPRECATED(ia))
379			REPLACE(3);
380
381		/* Rule 4: Prefer home addresses */
382		/*
383		 * XXX: This is a TODO.  We should probably merge the MIP6
384		 * case above.
385		 */
386
387		/* Rule 5: Prefer outgoing interface */
388		if (!(ND_IFINFO(ifp)->flags & ND6_IFF_NO_PREFER_IFACE)) {
389			if (ia_best->ia_ifp == ifp && ia->ia_ifp != ifp)
390				NEXT(5);
391			if (ia_best->ia_ifp != ifp && ia->ia_ifp == ifp)
392				REPLACE(5);
393		}
394
395		/*
396		 * Rule 6: Prefer matching label
397		 * Note that best_policy should be non-NULL here.
398		 */
399		if (dst_policy == NULL)
400			dst_policy = lookup_addrsel_policy(dstsock);
401		if (dst_policy->label != ADDR_LABEL_NOTAPP) {
402			new_policy = lookup_addrsel_policy(&ia->ia_addr);
403			if (dst_policy->label == best_policy->label &&
404			    dst_policy->label != new_policy->label)
405				NEXT(6);
406			if (dst_policy->label != best_policy->label &&
407			    dst_policy->label == new_policy->label)
408				REPLACE(6);
409		}
410
411		/*
412		 * Rule 7: Prefer public addresses.
413		 * We allow users to reverse the logic by configuring
414		 * a sysctl variable, so that privacy conscious users can
415		 * always prefer temporary addresses.
416		 */
417		if (opts == NULL ||
418		    opts->ip6po_prefer_tempaddr == IP6PO_TEMPADDR_SYSTEM) {
419			prefer_tempaddr = V_ip6_prefer_tempaddr;
420		} else if (opts->ip6po_prefer_tempaddr ==
421		    IP6PO_TEMPADDR_NOTPREFER) {
422			prefer_tempaddr = 0;
423		} else
424			prefer_tempaddr = 1;
425		if (!(ia_best->ia6_flags & IN6_IFF_TEMPORARY) &&
426		    (ia->ia6_flags & IN6_IFF_TEMPORARY)) {
427			if (prefer_tempaddr)
428				REPLACE(7);
429			else
430				NEXT(7);
431		}
432		if ((ia_best->ia6_flags & IN6_IFF_TEMPORARY) &&
433		    !(ia->ia6_flags & IN6_IFF_TEMPORARY)) {
434			if (prefer_tempaddr)
435				NEXT(7);
436			else
437				REPLACE(7);
438		}
439
440		/*
441		 * Rule 8: prefer addresses on alive interfaces.
442		 * This is a KAME specific rule.
443		 */
444		if ((ia_best->ia_ifp->if_flags & IFF_UP) &&
445		    !(ia->ia_ifp->if_flags & IFF_UP))
446			NEXT(8);
447		if (!(ia_best->ia_ifp->if_flags & IFF_UP) &&
448		    (ia->ia_ifp->if_flags & IFF_UP))
449			REPLACE(8);
450
451		/*
452		 * Rule 9: prefer address with better virtual status.
453		 */
454		if (ifa_preferred(&ia_best->ia_ifa, &ia->ia_ifa))
455			REPLACE(9);
456		if (ifa_preferred(&ia->ia_ifa, &ia_best->ia_ifa))
457			NEXT(9);
458
459		/*
460		 * Rule 10: prefer address with `prefer_source' flag.
461		 */
462		if ((ia_best->ia6_flags & IN6_IFF_PREFER_SOURCE) == 0 &&
463		    (ia->ia6_flags & IN6_IFF_PREFER_SOURCE) != 0)
464			REPLACE(10);
465		if ((ia_best->ia6_flags & IN6_IFF_PREFER_SOURCE) != 0 &&
466		    (ia->ia6_flags & IN6_IFF_PREFER_SOURCE) == 0)
467			NEXT(10);
468
469		/*
470		 * Rule 14: Use longest matching prefix.
471		 * Note: in the address selection draft, this rule is
472		 * documented as "Rule 8".  However, since it is also
473		 * documented that this rule can be overridden, we assign
474		 * a large number so that it is easy to assign smaller numbers
475		 * to more preferred rules.
476		 */
477		new_matchlen = in6_matchlen(&ia->ia_addr.sin6_addr, &dst);
478		if (best_matchlen < new_matchlen)
479			REPLACE(14);
480		if (new_matchlen < best_matchlen)
481			NEXT(14);
482
483		/* Rule 15 is reserved. */
484
485		/*
486		 * Last resort: just keep the current candidate.
487		 * Or, do we need more rules?
488		 */
489		continue;
490
491	  replace:
492		ia_best = ia;
493		best_scope = (new_scope >= 0 ? new_scope :
494			      in6_addrscope(&ia_best->ia_addr.sin6_addr));
495		best_policy = (new_policy ? new_policy :
496			       lookup_addrsel_policy(&ia_best->ia_addr));
497		best_matchlen = (new_matchlen >= 0 ? new_matchlen :
498				 in6_matchlen(&ia_best->ia_addr.sin6_addr,
499					      &dst));
500
501	  next:
502		continue;
503
504	  out:
505		break;
506	}
507
508	if ((ia = ia_best) == NULL) {
509		IN6_IFADDR_RUNLOCK(&in6_ifa_tracker);
510		IP6STAT_INC(ip6s_sources_none);
511		return (EADDRNOTAVAIL);
512	}
513
514	/*
515	 * At this point at least one of the addresses belonged to the jail
516	 * but it could still be, that we want to further restrict it, e.g.
517	 * theoratically IN6_IS_ADDR_LOOPBACK.
518	 * It must not be IN6_IS_ADDR_UNSPECIFIED anymore.
519	 * prison_local_ip6() will fix an IN6_IS_ADDR_LOOPBACK but should
520	 * let all others previously selected pass.
521	 * Use tmp to not change ::1 on lo0 to the primary jail address.
522	 */
523	tmp = ia->ia_addr.sin6_addr;
524	if (cred != NULL && prison_local_ip6(cred, &tmp, (inp != NULL &&
525	    (inp->inp_flags & IN6P_IPV6_V6ONLY) != 0)) != 0) {
526		IN6_IFADDR_RUNLOCK(&in6_ifa_tracker);
527		IP6STAT_INC(ip6s_sources_none);
528		return (EADDRNOTAVAIL);
529	}
530
531	if (ifpp)
532		*ifpp = ifp;
533
534	bcopy(&tmp, srcp, sizeof(*srcp));
535	if (ia->ia_ifp == ifp)
536		IP6STAT_INC(ip6s_sources_sameif[best_scope]);
537	else
538		IP6STAT_INC(ip6s_sources_otherif[best_scope]);
539	if (dst_scope == best_scope)
540		IP6STAT_INC(ip6s_sources_samescope[best_scope]);
541	else
542		IP6STAT_INC(ip6s_sources_otherscope[best_scope]);
543	if (IFA6_IS_DEPRECATED(ia))
544		IP6STAT_INC(ip6s_sources_deprecated[best_scope]);
545	IN6_IFADDR_RUNLOCK(&in6_ifa_tracker);
546	return (0);
547}
548
549/*
550 * Select source address based on @inp, @dstsock and @opts.
551 * Stores selected address to @srcp. If @scope_ambiguous is set,
552 * embed scope from selected outgoing interface. If @hlim pointer
553 * is provided, stores calculated hop limit there.
554 * Returns 0 on success.
555 */
556int
557in6_selectsrc_socket(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
558    struct inpcb *inp, struct ucred *cred, int scope_ambiguous,
559    struct in6_addr *srcp, int *hlim)
560{
561	struct ifnet *retifp;
562	uint32_t fibnum;
563	int error;
564
565	fibnum = inp->inp_inc.inc_fibnum;
566	retifp = NULL;
567
568	error = in6_selectsrc(fibnum, dstsock, opts, inp, cred, &retifp, srcp);
569	if (error != 0)
570		return (error);
571
572	if (hlim != NULL)
573		*hlim = in6_selecthlim(inp, retifp);
574
575	if (retifp == NULL || scope_ambiguous == 0)
576		return (0);
577
578	/*
579	 * Application should provide a proper zone ID or the use of
580	 * default zone IDs should be enabled.  Unfortunately, some
581	 * applications do not behave as it should, so we need a
582	 * workaround.  Even if an appropriate ID is not determined
583	 * (when it's required), if we can determine the outgoing
584	 * interface. determine the zone ID based on the interface.
585	 */
586	error = in6_setscope(&dstsock->sin6_addr, retifp, NULL);
587
588	return (error);
589}
590
591/*
592 * Select source address based on @fibnum, @dst and @scopeid.
593 * Stores selected address to @srcp.
594 * Returns 0 on success.
595 *
596 * Used by non-socket based consumers (ND code mostly)
597 */
598int
599in6_selectsrc_addr(uint32_t fibnum, const struct in6_addr *dst,
600    uint32_t scopeid, struct ifnet *ifp, struct in6_addr *srcp,
601    int *hlim)
602{
603	struct ifnet *retifp;
604	struct sockaddr_in6 dst_sa;
605	int error;
606
607	retifp = ifp;
608	bzero(&dst_sa, sizeof(dst_sa));
609	dst_sa.sin6_family = AF_INET6;
610	dst_sa.sin6_len = sizeof(dst_sa);
611	dst_sa.sin6_addr = *dst;
612	dst_sa.sin6_scope_id = scopeid;
613	sa6_embedscope(&dst_sa, 0);
614
615	error = in6_selectsrc(fibnum, &dst_sa, NULL, NULL, NULL, &retifp, srcp);
616	if (hlim != NULL)
617		*hlim = in6_selecthlim(NULL, retifp);
618
619	return (error);
620}
621
622/*
623 * clone - meaningful only for bsdi and freebsd
624 */
625static int
626selectroute(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
627    struct ip6_moptions *mopts, struct route_in6 *ro,
628    struct ifnet **retifp, struct rtentry **retrt, int norouteok, u_int fibnum)
629{
630	int error = 0;
631	struct ifnet *ifp = NULL;
632	struct rtentry *rt = NULL;
633	struct sockaddr_in6 *sin6_next;
634	struct in6_pktinfo *pi = NULL;
635	struct in6_addr *dst = &dstsock->sin6_addr;
636	uint32_t zoneid;
637#if 0
638	char ip6buf[INET6_ADDRSTRLEN];
639
640	if (dstsock->sin6_addr.s6_addr32[0] == 0 &&
641	    dstsock->sin6_addr.s6_addr32[1] == 0 &&
642	    !IN6_IS_ADDR_LOOPBACK(&dstsock->sin6_addr)) {
643		printf("%s: strange destination %s\n", __func__,
644		       ip6_sprintf(ip6buf, &dstsock->sin6_addr));
645	} else {
646		printf("%s: destination = %s%%%d\n", __func__,
647		       ip6_sprintf(ip6buf, &dstsock->sin6_addr),
648		       dstsock->sin6_scope_id); /* for debug */
649	}
650#endif
651
652	/* If the caller specify the outgoing interface explicitly, use it. */
653	if (opts && (pi = opts->ip6po_pktinfo) != NULL && pi->ipi6_ifindex) {
654		/* XXX boundary check is assumed to be already done. */
655		ifp = ifnet_byindex(pi->ipi6_ifindex);
656		if (ifp != NULL &&
657		    (norouteok || retrt == NULL ||
658		    IN6_IS_ADDR_MULTICAST(dst))) {
659			/*
660			 * we do not have to check or get the route for
661			 * multicast.
662			 */
663			goto done;
664		} else
665			goto getroute;
666	}
667	/*
668	 * If the destination address is a multicast address and the outgoing
669	 * interface for the address is specified by the caller, use it.
670	 */
671	if (IN6_IS_ADDR_MULTICAST(dst) &&
672	    mopts != NULL && (ifp = mopts->im6o_multicast_ifp) != NULL) {
673		goto done; /* we do not need a route for multicast. */
674	}
675	/*
676	 * If destination address is LLA or link- or node-local multicast,
677	 * use it's embedded scope zone id to determine outgoing interface.
678	 */
679	if (IN6_IS_ADDR_MC_LINKLOCAL(dst) ||
680	    IN6_IS_ADDR_MC_NODELOCAL(dst)) {
681		zoneid = ntohs(in6_getscope(dst));
682		if (zoneid > 0) {
683			ifp = in6_getlinkifnet(zoneid);
684			goto done;
685		}
686	}
687
688  getroute:
689	/*
690	 * If the next hop address for the packet is specified by the caller,
691	 * use it as the gateway.
692	 */
693	if (opts && opts->ip6po_nexthop) {
694		struct route_in6 *ron;
695
696		sin6_next = satosin6(opts->ip6po_nexthop);
697		if (IN6_IS_ADDR_LINKLOCAL(&sin6_next->sin6_addr)) {
698			/*
699			 * Next hop is LLA, thus it should be neighbor.
700			 * Determine outgoing interface by zone index.
701			 */
702			zoneid = ntohs(in6_getscope(&sin6_next->sin6_addr));
703			if (zoneid > 0) {
704				ifp = in6_getlinkifnet(zoneid);
705				goto done;
706			}
707		}
708		ron = &opts->ip6po_nextroute;
709		/* Use a cached route if it exists and is valid. */
710		if (ron->ro_rt != NULL && (
711		    (ron->ro_rt->rt_flags & RTF_UP) == 0 ||
712		    ron->ro_dst.sin6_family != AF_INET6 ||
713		    !IN6_ARE_ADDR_EQUAL(&ron->ro_dst.sin6_addr,
714			&sin6_next->sin6_addr)))
715			RO_RTFREE(ron);
716		if (ron->ro_rt == NULL) {
717			ron->ro_dst = *sin6_next;
718			in6_rtalloc(ron, fibnum); /* multi path case? */
719		}
720		/*
721		 * The node identified by that address must be a
722		 * neighbor of the sending host.
723		 */
724		if (ron->ro_rt == NULL ||
725		    (ron->ro_rt->rt_flags & RTF_GATEWAY) != 0)
726			error = EHOSTUNREACH;
727		else {
728			rt = ron->ro_rt;
729			ifp = rt->rt_ifp;
730		}
731		goto done;
732	}
733
734	/*
735	 * Use a cached route if it exists and is valid, else try to allocate
736	 * a new one.  Note that we should check the address family of the
737	 * cached destination, in case of sharing the cache with IPv4.
738	 */
739	if (ro) {
740		if (ro->ro_rt &&
741		    (!(ro->ro_rt->rt_flags & RTF_UP) ||
742		     ((struct sockaddr *)(&ro->ro_dst))->sa_family != AF_INET6 ||
743		     !IN6_ARE_ADDR_EQUAL(&satosin6(&ro->ro_dst)->sin6_addr,
744		     dst))) {
745			RTFREE(ro->ro_rt);
746			ro->ro_rt = (struct rtentry *)NULL;
747		}
748		if (ro->ro_rt == (struct rtentry *)NULL) {
749			struct sockaddr_in6 *sa6;
750
751			/* No route yet, so try to acquire one */
752			bzero(&ro->ro_dst, sizeof(struct sockaddr_in6));
753			sa6 = (struct sockaddr_in6 *)&ro->ro_dst;
754			*sa6 = *dstsock;
755			sa6->sin6_scope_id = 0;
756
757#ifdef RADIX_MPATH
758				rtalloc_mpath_fib((struct route *)ro,
759				    ntohl(sa6->sin6_addr.s6_addr32[3]), fibnum);
760#else
761				ro->ro_rt = in6_rtalloc1((struct sockaddr *)
762				    &ro->ro_dst, 0, 0UL, fibnum);
763				if (ro->ro_rt)
764					RT_UNLOCK(ro->ro_rt);
765#endif
766		}
767
768		/*
769		 * do not care about the result if we have the nexthop
770		 * explicitly specified.
771		 */
772		if (opts && opts->ip6po_nexthop)
773			goto done;
774
775		if (ro->ro_rt) {
776			ifp = ro->ro_rt->rt_ifp;
777
778			if (ifp == NULL) { /* can this really happen? */
779				RTFREE(ro->ro_rt);
780				ro->ro_rt = NULL;
781			}
782		}
783		if (ro->ro_rt == NULL)
784			error = EHOSTUNREACH;
785		rt = ro->ro_rt;
786
787		/*
788		 * Check if the outgoing interface conflicts with
789		 * the interface specified by ipi6_ifindex (if specified).
790		 * Note that loopback interface is always okay.
791		 * (this may happen when we are sending a packet to one of
792		 *  our own addresses.)
793		 */
794		if (ifp && opts && opts->ip6po_pktinfo &&
795		    opts->ip6po_pktinfo->ipi6_ifindex) {
796			if (!(ifp->if_flags & IFF_LOOPBACK) &&
797			    ifp->if_index !=
798			    opts->ip6po_pktinfo->ipi6_ifindex) {
799				error = EHOSTUNREACH;
800				goto done;
801			}
802		}
803	}
804
805  done:
806	if (ifp == NULL && rt == NULL) {
807		/*
808		 * This can happen if the caller did not pass a cached route
809		 * nor any other hints.  We treat this case an error.
810		 */
811		error = EHOSTUNREACH;
812	}
813	if (error == EHOSTUNREACH)
814		IP6STAT_INC(ip6s_noroute);
815
816	if (retifp != NULL) {
817		*retifp = ifp;
818
819		/*
820		 * Adjust the "outgoing" interface.  If we're going to loop
821		 * the packet back to ourselves, the ifp would be the loopback
822		 * interface. However, we'd rather know the interface associated
823		 * to the destination address (which should probably be one of
824		 * our own addresses.)
825		 */
826		if (rt) {
827			if ((rt->rt_ifp->if_flags & IFF_LOOPBACK) &&
828			    (rt->rt_gateway->sa_family == AF_LINK))
829				*retifp =
830					ifnet_byindex(((struct sockaddr_dl *)
831						       rt->rt_gateway)->sdl_index);
832		}
833	}
834
835	if (retrt != NULL)
836		*retrt = rt;	/* rt may be NULL */
837
838	return (error);
839}
840
841static int
842in6_selectif(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
843    struct ip6_moptions *mopts, struct ifnet **retifp,
844    struct ifnet *oifp, u_int fibnum)
845{
846	int error;
847	struct route_in6 sro;
848	struct rtentry *rt = NULL;
849	int rt_flags;
850
851	KASSERT(retifp != NULL, ("%s: retifp is NULL", __func__));
852
853	bzero(&sro, sizeof(sro));
854	rt_flags = 0;
855
856	error = selectroute(dstsock, opts, mopts, &sro, retifp, &rt, 1, fibnum);
857
858	if (rt)
859		rt_flags = rt->rt_flags;
860	if (rt && rt == sro.ro_rt)
861		RTFREE(rt);
862
863	if (error != 0) {
864		/* Help ND. See oifp comment in in6_selectsrc(). */
865		if (oifp != NULL && fibnum == RT_DEFAULT_FIB) {
866			*retifp = oifp;
867			error = 0;
868		}
869		return (error);
870	}
871
872	/*
873	 * do not use a rejected or black hole route.
874	 * XXX: this check should be done in the L2 output routine.
875	 * However, if we skipped this check here, we'd see the following
876	 * scenario:
877	 * - install a rejected route for a scoped address prefix
878	 *   (like fe80::/10)
879	 * - send a packet to a destination that matches the scoped prefix,
880	 *   with ambiguity about the scope zone.
881	 * - pick the outgoing interface from the route, and disambiguate the
882	 *   scope zone with the interface.
883	 * - ip6_output() would try to get another route with the "new"
884	 *   destination, which may be valid.
885	 * - we'd see no error on output.
886	 * Although this may not be very harmful, it should still be confusing.
887	 * We thus reject the case here.
888	 */
889
890	if (rt_flags & (RTF_REJECT | RTF_BLACKHOLE)) {
891		error = (rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
892		return (error);
893	}
894
895	return (0);
896}
897
898/* Public wrapper function to selectroute(). */
899int
900in6_selectroute(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
901    struct ip6_moptions *mopts, struct route_in6 *ro,
902    struct ifnet **retifp, struct rtentry **retrt, u_int fibnum)
903{
904
905	return (selectroute(dstsock, opts, mopts, ro, retifp,
906	    retrt, 0, fibnum));
907}
908
909/*
910 * Default hop limit selection. The precedence is as follows:
911 * 1. Hoplimit value specified via ioctl.
912 * 2. (If the outgoing interface is detected) the current
913 *     hop limit of the interface specified by router advertisement.
914 * 3. The system default hoplimit.
915 */
916int
917in6_selecthlim(struct inpcb *inp, struct ifnet *ifp)
918{
919
920	if (inp && inp->in6p_hops >= 0)
921		return (inp->in6p_hops);
922	else if (ifp)
923		return (ND_IFINFO(ifp)->chlim);
924	else if (inp && !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
925		struct nhop6_basic nh6;
926		struct in6_addr dst;
927		uint32_t fibnum, scopeid;
928		int hlim;
929
930		fibnum = inp->inp_inc.inc_fibnum;
931		in6_splitscope(&inp->in6p_faddr, &dst, &scopeid);
932		if (fib6_lookup_nh_basic(fibnum, &dst, scopeid, 0, 0, &nh6)==0){
933			hlim = ND_IFINFO(nh6.nh_ifp)->chlim;
934			return (hlim);
935		}
936	}
937	return (V_ip6_defhlim);
938}
939
940/*
941 * XXX: this is borrowed from in6_pcbbind(). If possible, we should
942 * share this function by all *bsd*...
943 */
944int
945in6_pcbsetport(struct in6_addr *laddr, struct inpcb *inp, struct ucred *cred)
946{
947	struct socket *so = inp->inp_socket;
948	u_int16_t lport = 0;
949	int error, lookupflags = 0;
950#ifdef INVARIANTS
951	struct inpcbinfo *pcbinfo = inp->inp_pcbinfo;
952#endif
953
954	INP_WLOCK_ASSERT(inp);
955	INP_HASH_WLOCK_ASSERT(pcbinfo);
956
957	error = prison_local_ip6(cred, laddr,
958	    ((inp->inp_flags & IN6P_IPV6_V6ONLY) != 0));
959	if (error)
960		return(error);
961
962	/* XXX: this is redundant when called from in6_pcbbind */
963	if ((so->so_options & (SO_REUSEADDR|SO_REUSEPORT|SO_REUSEPORT_LB)) == 0)
964		lookupflags = INPLOOKUP_WILDCARD;
965
966	inp->inp_flags |= INP_ANONPORT;
967
968	error = in_pcb_lport(inp, NULL, &lport, cred, lookupflags);
969	if (error != 0)
970		return (error);
971
972	inp->inp_lport = lport;
973	if (in_pcbinshash(inp) != 0) {
974		inp->in6p_laddr = in6addr_any;
975		inp->inp_lport = 0;
976		return (EAGAIN);
977	}
978
979	return (0);
980}
981
982void
983addrsel_policy_init(void)
984{
985
986	init_policy_queue();
987
988	/* initialize the "last resort" policy */
989	bzero(&V_defaultaddrpolicy, sizeof(V_defaultaddrpolicy));
990	V_defaultaddrpolicy.label = ADDR_LABEL_NOTAPP;
991
992	if (!IS_DEFAULT_VNET(curvnet))
993		return;
994
995	ADDRSEL_LOCK_INIT();
996	ADDRSEL_SXLOCK_INIT();
997}
998
999static struct in6_addrpolicy *
1000lookup_addrsel_policy(struct sockaddr_in6 *key)
1001{
1002	struct in6_addrpolicy *match = NULL;
1003
1004	ADDRSEL_LOCK();
1005	match = match_addrsel_policy(key);
1006
1007	if (match == NULL)
1008		match = &V_defaultaddrpolicy;
1009	else
1010		match->use++;
1011	ADDRSEL_UNLOCK();
1012
1013	return (match);
1014}
1015
1016/*
1017 * Subroutines to manage the address selection policy table via sysctl.
1018 */
1019struct walkarg {
1020	struct sysctl_req *w_req;
1021};
1022
1023static int in6_src_sysctl(SYSCTL_HANDLER_ARGS);
1024SYSCTL_DECL(_net_inet6_ip6);
1025static SYSCTL_NODE(_net_inet6_ip6, IPV6CTL_ADDRCTLPOLICY, addrctlpolicy,
1026    CTLFLAG_RD | CTLFLAG_MPSAFE, in6_src_sysctl,
1027    "");
1028
1029static int
1030in6_src_sysctl(SYSCTL_HANDLER_ARGS)
1031{
1032	struct walkarg w;
1033
1034	if (req->newptr)
1035		return EPERM;
1036
1037	bzero(&w, sizeof(w));
1038	w.w_req = req;
1039
1040	return (walk_addrsel_policy(dump_addrsel_policyent, &w));
1041}
1042
1043int
1044in6_src_ioctl(u_long cmd, caddr_t data)
1045{
1046	struct in6_addrpolicy ent0;
1047
1048	if (cmd != SIOCAADDRCTL_POLICY && cmd != SIOCDADDRCTL_POLICY)
1049		return (EOPNOTSUPP); /* check for safety */
1050
1051	ent0 = *(struct in6_addrpolicy *)data;
1052
1053	if (ent0.label == ADDR_LABEL_NOTAPP)
1054		return (EINVAL);
1055	/* check if the prefix mask is consecutive. */
1056	if (in6_mask2len(&ent0.addrmask.sin6_addr, NULL) < 0)
1057		return (EINVAL);
1058	/* clear trailing garbages (if any) of the prefix address. */
1059	IN6_MASK_ADDR(&ent0.addr.sin6_addr, &ent0.addrmask.sin6_addr);
1060	ent0.use = 0;
1061
1062	switch (cmd) {
1063	case SIOCAADDRCTL_POLICY:
1064		return (add_addrsel_policyent(&ent0));
1065	case SIOCDADDRCTL_POLICY:
1066		return (delete_addrsel_policyent(&ent0));
1067	}
1068
1069	return (0);		/* XXX: compromise compilers */
1070}
1071
1072/*
1073 * The followings are implementation of the policy table using a
1074 * simple tail queue.
1075 * XXX such details should be hidden.
1076 * XXX implementation using binary tree should be more efficient.
1077 */
1078struct addrsel_policyent {
1079	TAILQ_ENTRY(addrsel_policyent) ape_entry;
1080	struct in6_addrpolicy ape_policy;
1081};
1082
1083TAILQ_HEAD(addrsel_policyhead, addrsel_policyent);
1084
1085VNET_DEFINE_STATIC(struct addrsel_policyhead, addrsel_policytab);
1086#define	V_addrsel_policytab		VNET(addrsel_policytab)
1087
1088static void
1089init_policy_queue(void)
1090{
1091
1092	TAILQ_INIT(&V_addrsel_policytab);
1093}
1094
1095static int
1096add_addrsel_policyent(struct in6_addrpolicy *newpolicy)
1097{
1098	struct addrsel_policyent *new, *pol;
1099
1100	new = malloc(sizeof(*new), M_IFADDR,
1101	       M_WAITOK);
1102	ADDRSEL_XLOCK();
1103	ADDRSEL_LOCK();
1104
1105	/* duplication check */
1106	TAILQ_FOREACH(pol, &V_addrsel_policytab, ape_entry) {
1107		if (IN6_ARE_ADDR_EQUAL(&newpolicy->addr.sin6_addr,
1108				       &pol->ape_policy.addr.sin6_addr) &&
1109		    IN6_ARE_ADDR_EQUAL(&newpolicy->addrmask.sin6_addr,
1110				       &pol->ape_policy.addrmask.sin6_addr)) {
1111			ADDRSEL_UNLOCK();
1112			ADDRSEL_XUNLOCK();
1113			free(new, M_IFADDR);
1114			return (EEXIST);	/* or override it? */
1115		}
1116	}
1117
1118	bzero(new, sizeof(*new));
1119
1120	/* XXX: should validate entry */
1121	new->ape_policy = *newpolicy;
1122
1123	TAILQ_INSERT_TAIL(&V_addrsel_policytab, new, ape_entry);
1124	ADDRSEL_UNLOCK();
1125	ADDRSEL_XUNLOCK();
1126
1127	return (0);
1128}
1129
1130static int
1131delete_addrsel_policyent(struct in6_addrpolicy *key)
1132{
1133	struct addrsel_policyent *pol;
1134
1135	ADDRSEL_XLOCK();
1136	ADDRSEL_LOCK();
1137
1138	/* search for the entry in the table */
1139	TAILQ_FOREACH(pol, &V_addrsel_policytab, ape_entry) {
1140		if (IN6_ARE_ADDR_EQUAL(&key->addr.sin6_addr,
1141		    &pol->ape_policy.addr.sin6_addr) &&
1142		    IN6_ARE_ADDR_EQUAL(&key->addrmask.sin6_addr,
1143		    &pol->ape_policy.addrmask.sin6_addr)) {
1144			break;
1145		}
1146	}
1147	if (pol == NULL) {
1148		ADDRSEL_UNLOCK();
1149		ADDRSEL_XUNLOCK();
1150		return (ESRCH);
1151	}
1152
1153	TAILQ_REMOVE(&V_addrsel_policytab, pol, ape_entry);
1154	ADDRSEL_UNLOCK();
1155	ADDRSEL_XUNLOCK();
1156	free(pol, M_IFADDR);
1157
1158	return (0);
1159}
1160
1161static int
1162walk_addrsel_policy(int (*callback)(struct in6_addrpolicy *, void *), void *w)
1163{
1164	struct addrsel_policyent *pol;
1165	int error = 0;
1166
1167	ADDRSEL_SLOCK();
1168	TAILQ_FOREACH(pol, &V_addrsel_policytab, ape_entry) {
1169		if ((error = (*callback)(&pol->ape_policy, w)) != 0) {
1170			ADDRSEL_SUNLOCK();
1171			return (error);
1172		}
1173	}
1174	ADDRSEL_SUNLOCK();
1175	return (error);
1176}
1177
1178static int
1179dump_addrsel_policyent(struct in6_addrpolicy *pol, void *arg)
1180{
1181	int error = 0;
1182	struct walkarg *w = arg;
1183
1184	error = SYSCTL_OUT(w->w_req, pol, sizeof(*pol));
1185
1186	return (error);
1187}
1188
1189static struct in6_addrpolicy *
1190match_addrsel_policy(struct sockaddr_in6 *key)
1191{
1192	struct addrsel_policyent *pent;
1193	struct in6_addrpolicy *bestpol = NULL, *pol;
1194	int matchlen, bestmatchlen = -1;
1195	u_char *mp, *ep, *k, *p, m;
1196
1197	TAILQ_FOREACH(pent, &V_addrsel_policytab, ape_entry) {
1198		matchlen = 0;
1199
1200		pol = &pent->ape_policy;
1201		mp = (u_char *)&pol->addrmask.sin6_addr;
1202		ep = mp + 16;	/* XXX: scope field? */
1203		k = (u_char *)&key->sin6_addr;
1204		p = (u_char *)&pol->addr.sin6_addr;
1205		for (; mp < ep && *mp; mp++, k++, p++) {
1206			m = *mp;
1207			if ((*k & m) != *p)
1208				goto next; /* not match */
1209			if (m == 0xff) /* short cut for a typical case */
1210				matchlen += 8;
1211			else {
1212				while (m >= 0x80) {
1213					matchlen++;
1214					m <<= 1;
1215				}
1216			}
1217		}
1218
1219		/* matched.  check if this is better than the current best. */
1220		if (bestpol == NULL ||
1221		    matchlen > bestmatchlen) {
1222			bestpol = pol;
1223			bestmatchlen = matchlen;
1224		}
1225
1226	  next:
1227		continue;
1228	}
1229
1230	return (bestpol);
1231}
1232