rtsold.c revision 124526 
1/*	$KAME: rtsold.c,v 1.67 2003/05/17 18:16:15 itojun Exp $	*/
2
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 * $FreeBSD: head/usr.sbin/rtsold/rtsold.c 124526 2004-01-14 17:59:38Z ume $
32 */
33
34#include <sys/types.h>
35#include <sys/time.h>
36#include <sys/socket.h>
37#include <sys/param.h>
38
39#include <net/if.h>
40#include <net/if_dl.h>
41
42#include <netinet/in.h>
43#include <netinet/icmp6.h>
44
45#include <signal.h>
46#include <unistd.h>
47#include <syslog.h>
48#include <string.h>
49#include <stdlib.h>
50#include <stdio.h>
51#include <errno.h>
52#include <err.h>
53#include <stdarg.h>
54#include <ifaddrs.h>
55#ifdef HAVE_POLL_H
56#include <poll.h>
57#endif
58
59#include "rtsold.h"
60
61struct ifinfo *iflist;
62struct timeval tm_max =	{0x7fffffff, 0x7fffffff};
63static int log_upto = 999;
64static int fflag = 0;
65static int Fflag = 0;	/* force setting sysctl parameters */
66
67int aflag = 0;
68int dflag = 0;
69
70char *otherconf_script;
71
72/* protocol constatns */
73#define MAX_RTR_SOLICITATION_DELAY	1 /* second */
74#define RTR_SOLICITATION_INTERVAL	4 /* seconds */
75#define MAX_RTR_SOLICITATIONS		3 /* times */
76
77/*
78 * implementation dependent constants in seconds
79 * XXX: should be configurable
80 */
81#define PROBE_INTERVAL 60
82
83int main __P((int, char **));
84
85/* static variables and functions */
86static int mobile_node = 0;
87#ifndef SMALL
88static int do_dump;
89static char *dumpfilename = "/var/run/rtsold.dump"; /* XXX: should be configurable */
90#endif
91#if 1
92static char *pidfilename = "/var/run/rtsold.pid"; /* should be configurable */
93#endif
94
95#if 0
96static int ifreconfig __P((char *));
97#endif
98static int make_packet __P((struct ifinfo *));
99static struct timeval *rtsol_check_timer __P((void));
100
101#ifndef SMALL
102static void rtsold_set_dump_file __P((int));
103#endif
104static void usage __P((char *));
105
106int
107main(int argc, char **argv)
108{
109	int s, ch, once = 0;
110	struct timeval *timeout;
111	char *argv0, *opts;
112#ifdef HAVE_POLL_H
113	struct pollfd set[2];
114#else
115	fd_set *fdsetp, *selectfdp;
116	int fdmasks;
117	int maxfd;
118#endif
119	int rtsock;
120
121	/*
122	 * Initialization
123	 */
124	argv0 = argv[0];
125
126	/* get option */
127	if (argv0 && argv0[strlen(argv0) - 1] != 'd') {
128		fflag = 1;
129		once = 1;
130		opts = "adDFO:";
131	} else
132		opts = "adDfFm1O:";
133
134	while ((ch = getopt(argc, argv, opts)) != -1) {
135		switch (ch) {
136		case 'a':
137			aflag = 1;
138			break;
139		case 'd':
140			dflag = 1;
141			break;
142		case 'D':
143			dflag = 2;
144			break;
145		case 'f':
146			fflag = 1;
147			break;
148		case 'F':
149			Fflag = 1;
150			break;
151		case 'm':
152			mobile_node = 1;
153			break;
154		case '1':
155			once = 1;
156			break;
157		case 'O':
158			otherconf_script = optarg;
159			break;
160		default:
161			usage(argv0);
162			/*NOTREACHED*/
163		}
164	}
165	argc -= optind;
166	argv += optind;
167
168	if ((!aflag && argc == 0) || (aflag && argc != 0)) {
169		usage(argv0);
170		/*NOTREACHED*/
171	}
172
173	/* set log level */
174	if (dflag == 0)
175		log_upto = LOG_NOTICE;
176	if (!fflag) {
177		char *ident;
178
179		ident = strrchr(argv0, '/');
180		if (!ident)
181			ident = argv0;
182		else
183			ident++;
184		openlog(ident, LOG_NDELAY|LOG_PID, LOG_DAEMON);
185		if (log_upto >= 0)
186			setlogmask(LOG_UPTO(log_upto));
187	}
188
189	if (otherconf_script && *otherconf_script != '/') {
190		errx(1, "configuration script (%s) must be an absolute path",
191		    otherconf_script);
192	}
193
194#ifndef HAVE_ARC4RANDOM
195	/* random value initialization */
196	srandom((u_long)time(NULL));
197#endif
198
199	if (Fflag) {
200		setinet6sysctl(IPV6CTL_ACCEPT_RTADV, 1);
201		setinet6sysctl(IPV6CTL_FORWARDING, 0);
202	} else {
203		/* warn if accept_rtadv is down */
204		if (!getinet6sysctl(IPV6CTL_ACCEPT_RTADV))
205			warnx("kernel is configured not to accept RAs");
206		/* warn if forwarding is up */
207		if (getinet6sysctl(IPV6CTL_FORWARDING))
208			warnx("kernel is configured as a router, not a host");
209	}
210
211#ifndef SMALL
212	/* initialization to dump internal status to a file */
213	signal(SIGUSR1, rtsold_set_dump_file);
214#endif
215
216	if (!fflag)
217		daemon(0, 0);		/* act as a daemon */
218
219	/*
220	 * Open a socket for sending RS and receiving RA.
221	 * This should be done before calling ifinit(), since the function
222	 * uses the socket.
223	 */
224	if ((s = sockopen()) < 0) {
225		warnmsg(LOG_ERR, __func__, "failed to open a socket");
226		exit(1);
227		/*NOTREACHED*/
228	}
229#ifdef HAVE_POLL_H
230	set[0].fd = s;
231	set[0].events = POLLIN;
232#else
233	maxfd = s;
234#endif
235
236#ifdef HAVE_POLL_H
237	set[1].fd = -1;
238#endif
239
240	if ((rtsock = rtsock_open()) < 0) {
241		warnmsg(LOG_ERR, __func__, "failed to open a socket");
242		exit(1);
243		/*NOTREACHED*/
244	}
245#ifdef HAVE_POLL_H
246	set[1].fd = rtsock;
247	set[1].events = POLLIN;
248#else
249	if (rtsock > maxfd)
250		maxfd = rtsock;
251#endif
252
253#ifndef HAVE_POLL_H
254	fdmasks = howmany(maxfd + 1, NFDBITS) * sizeof(fd_mask);
255	if ((fdsetp = malloc(fdmasks)) == NULL) {
256		err(1, "malloc");
257		/*NOTREACHED*/
258	}
259	if ((selectfdp = malloc(fdmasks)) == NULL) {
260		err(1, "malloc");
261		/*NOTREACHED*/
262	}
263#endif
264
265	/* configuration per interface */
266	if (ifinit()) {
267		warnmsg(LOG_ERR, __func__,
268		    "failed to initilizatoin interfaces");
269		exit(1);
270		/*NOTREACHED*/
271	}
272	if (aflag)
273		argv = autoifprobe();
274	while (argv && *argv) {
275		if (ifconfig(*argv)) {
276			warnmsg(LOG_ERR, __func__,
277			    "failed to initialize %s", *argv);
278			exit(1);
279			/*NOTREACHED*/
280		}
281		argv++;
282	}
283
284	/* setup for probing default routers */
285	if (probe_init()) {
286		warnmsg(LOG_ERR, __func__,
287		    "failed to setup for probing routers");
288		exit(1);
289		/*NOTREACHED*/
290	}
291
292#if 1
293	/* dump the current pid */
294	if (!once) {
295		pid_t pid = getpid();
296		FILE *fp;
297
298		if ((fp = fopen(pidfilename, "w")) == NULL)
299			warnmsg(LOG_ERR, __func__,
300			    "failed to open a pid log file(%s): %s",
301			    pidfilename, strerror(errno));
302		else {
303			fprintf(fp, "%d\n", pid);
304			fclose(fp);
305		}
306	}
307#endif
308
309#ifndef HAVE_POLL_H
310	memset(fdsetp, 0, fdmasks);
311	FD_SET(s, fdsetp);
312	FD_SET(rtsock, fdsetp);
313#endif
314	while (1) {		/* main loop */
315		int e;
316
317#ifndef HAVE_POLL_H
318		memcpy(selectfdp, fdsetp, fdmasks);
319#endif
320
321#ifndef SMALL
322		if (do_dump) {	/* SIGUSR1 */
323			do_dump = 0;
324			rtsold_dump_file(dumpfilename);
325		}
326#endif
327
328		timeout = rtsol_check_timer();
329
330		if (once) {
331			struct ifinfo *ifi;
332
333			/* if we have no timeout, we are done (or failed) */
334			if (timeout == NULL)
335				break;
336
337			/* if all interfaces have got RA packet, we are done */
338			for (ifi = iflist; ifi; ifi = ifi->next) {
339				if (ifi->state != IFS_DOWN && ifi->racnt == 0)
340					break;
341			}
342			if (ifi == NULL)
343				break;
344		}
345#ifdef HAVE_POLL_H
346		e = poll(set, 2, timeout ? (timeout->tv_sec * 1000 + timeout->tv_usec / 1000) : INFTIM);
347#else
348		e = select(maxfd + 1, selectfdp, NULL, NULL, timeout);
349#endif
350		if (e < 1) {
351			if (e < 0 && errno != EINTR) {
352				warnmsg(LOG_ERR, __func__, "select: %s",
353				    strerror(errno));
354			}
355			continue;
356		}
357
358		/* packet reception */
359#ifdef HAVE_POLL_H
360		if (set[1].revents & POLLIN)
361#else
362		if (FD_ISSET(rtsock, selectfdp))
363#endif
364			rtsock_input(rtsock);
365#ifdef HAVE_POLL_H
366		if (set[0].revents & POLLIN)
367#else
368		if (FD_ISSET(s, selectfdp))
369#endif
370			rtsol_input(s);
371	}
372	/* NOTREACHED */
373
374	return 0;
375}
376
377int
378ifconfig(char *ifname)
379{
380	struct ifinfo *ifinfo;
381	struct sockaddr_dl *sdl;
382	int flags;
383
384	if ((sdl = if_nametosdl(ifname)) == NULL) {
385		warnmsg(LOG_ERR, __func__,
386		    "failed to get link layer information for %s", ifname);
387		return(-1);
388	}
389	if (find_ifinfo(sdl->sdl_index)) {
390		warnmsg(LOG_ERR, __func__,
391		    "interface %s was already configured", ifname);
392		free(sdl);
393		return(-1);
394	}
395
396	if ((ifinfo = malloc(sizeof(*ifinfo))) == NULL) {
397		warnmsg(LOG_ERR, __func__, "memory allocation failed");
398		free(sdl);
399		return(-1);
400	}
401	memset(ifinfo, 0, sizeof(*ifinfo));
402	ifinfo->sdl = sdl;
403
404	strlcpy(ifinfo->ifname, ifname, sizeof(ifinfo->ifname));
405
406	/* construct a router solicitation message */
407	if (make_packet(ifinfo))
408		goto bad;
409
410	/* set link ID of this interface. */
411#ifdef HAVE_SCOPELIB
412	if (inet_zoneid(AF_INET6, 2, ifname, &ifinfo->linkid))
413		goto bad;
414#else
415	/* XXX: assume interface IDs as link IDs */
416	ifinfo->linkid = ifinfo->sdl->sdl_index;
417#endif
418
419	/*
420	 * check if the interface is available.
421	 * also check if SIOCGIFMEDIA ioctl is OK on the interface.
422	 */
423	ifinfo->mediareqok = 1;
424	ifinfo->active = interface_status(ifinfo);
425	if (!ifinfo->mediareqok) {
426		/*
427		 * probe routers periodically even if the link status
428		 * does not change.
429		 */
430		ifinfo->probeinterval = PROBE_INTERVAL;
431	}
432
433	/* activate interface: interface_up returns 0 on success */
434	flags = interface_up(ifinfo->ifname);
435	if (flags == 0)
436		ifinfo->state = IFS_DELAY;
437	else if (flags == IFS_TENTATIVE)
438		ifinfo->state = IFS_TENTATIVE;
439	else
440		ifinfo->state = IFS_DOWN;
441
442	rtsol_timer_update(ifinfo);
443
444	/* link into chain */
445	if (iflist)
446		ifinfo->next = iflist;
447	iflist = ifinfo;
448
449	return(0);
450
451bad:
452	free(ifinfo->sdl);
453	free(ifinfo);
454	return(-1);
455}
456
457void
458iflist_init(void)
459{
460	struct ifinfo *ifi, *next;
461
462	for (ifi = iflist; ifi; ifi = next) {
463		next = ifi->next;
464		if (ifi->sdl)
465			free(ifi->sdl);
466		if (ifi->rs_data)
467			free(ifi->rs_data);
468		free(ifi);
469		iflist = NULL;
470	}
471}
472
473#if 0
474static int
475ifreconfig(char *ifname)
476{
477	struct ifinfo *ifi, *prev;
478	int rv;
479
480	prev = NULL;
481	for (ifi = iflist; ifi; ifi = ifi->next) {
482		if (strncmp(ifi->ifname, ifname, sizeof(ifi->ifname)) == 0)
483			break;
484		prev = ifi;
485	}
486	prev->next = ifi->next;
487
488	rv = ifconfig(ifname);
489
490	/* reclaim it after ifconfig() in case ifname is pointer inside ifi */
491	if (ifi->rs_data)
492		free(ifi->rs_data);
493	free(ifi->sdl);
494	free(ifi);
495	return rv;
496}
497#endif
498
499struct ifinfo *
500find_ifinfo(int ifindex)
501{
502	struct ifinfo *ifi;
503
504	for (ifi = iflist; ifi; ifi = ifi->next)
505		if (ifi->sdl->sdl_index == ifindex)
506			return(ifi);
507	return(NULL);
508}
509
510static int
511make_packet(struct ifinfo *ifinfo)
512{
513	size_t packlen = sizeof(struct nd_router_solicit), lladdroptlen = 0;
514	struct nd_router_solicit *rs;
515	char *buf;
516
517	if ((lladdroptlen = lladdropt_length(ifinfo->sdl)) == 0) {
518		warnmsg(LOG_INFO, __func__,
519		    "link-layer address option has null length"
520		    " on %s. Treat as not included.", ifinfo->ifname);
521	}
522	packlen += lladdroptlen;
523	ifinfo->rs_datalen = packlen;
524
525	/* allocate buffer */
526	if ((buf = malloc(packlen)) == NULL) {
527		warnmsg(LOG_ERR, __func__,
528		    "memory allocation failed for %s", ifinfo->ifname);
529		return(-1);
530	}
531	ifinfo->rs_data = buf;
532
533	/* fill in the message */
534	rs = (struct nd_router_solicit *)buf;
535	rs->nd_rs_type = ND_ROUTER_SOLICIT;
536	rs->nd_rs_code = 0;
537	rs->nd_rs_cksum = 0;
538	rs->nd_rs_reserved = 0;
539	buf += sizeof(*rs);
540
541	/* fill in source link-layer address option */
542	if (lladdroptlen)
543		lladdropt_fill(ifinfo->sdl, (struct nd_opt_hdr *)buf);
544
545	return(0);
546}
547
548static struct timeval *
549rtsol_check_timer(void)
550{
551	static struct timeval returnval;
552	struct timeval now, rtsol_timer;
553	struct ifinfo *ifinfo;
554	int flags;
555
556	gettimeofday(&now, NULL);
557
558	rtsol_timer = tm_max;
559
560	for (ifinfo = iflist; ifinfo; ifinfo = ifinfo->next) {
561		if (timercmp(&ifinfo->expire, &now, <=)) {
562			if (dflag > 1)
563				warnmsg(LOG_DEBUG, __func__,
564				    "timer expiration on %s, "
565				    "state = %d", ifinfo->ifname,
566				    ifinfo->state);
567
568			switch (ifinfo->state) {
569			case IFS_DOWN:
570			case IFS_TENTATIVE:
571				/* interface_up returns 0 on success */
572				flags = interface_up(ifinfo->ifname);
573				if (flags == 0)
574					ifinfo->state = IFS_DELAY;
575				else if (flags == IFS_TENTATIVE)
576					ifinfo->state = IFS_TENTATIVE;
577				else
578					ifinfo->state = IFS_DOWN;
579				break;
580			case IFS_IDLE:
581			{
582				int oldstatus = ifinfo->active;
583				int probe = 0;
584
585				ifinfo->active = interface_status(ifinfo);
586
587				if (oldstatus != ifinfo->active) {
588					warnmsg(LOG_DEBUG, __func__,
589					    "%s status is changed"
590					    " from %d to %d",
591					    ifinfo->ifname,
592					    oldstatus, ifinfo->active);
593					probe = 1;
594					ifinfo->state = IFS_DELAY;
595				} else if (ifinfo->probeinterval &&
596				    (ifinfo->probetimer -=
597				    ifinfo->timer.tv_sec) <= 0) {
598					/* probe timer expired */
599					ifinfo->probetimer =
600					    ifinfo->probeinterval;
601					probe = 1;
602					ifinfo->state = IFS_PROBE;
603				}
604
605				/*
606				 * If we need a probe, clear the previous
607				 * status wrt the "other" configuration.
608				 */
609				if (probe)
610					ifinfo->otherconfig = 0;
611
612				if (probe && mobile_node)
613					defrouter_probe(ifinfo);
614				break;
615			}
616			case IFS_DELAY:
617				ifinfo->state = IFS_PROBE;
618				sendpacket(ifinfo);
619				break;
620			case IFS_PROBE:
621				if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
622					sendpacket(ifinfo);
623				else {
624					warnmsg(LOG_INFO, __func__,
625					    "No answer after sending %d RSs",
626					    ifinfo->probes);
627					ifinfo->probes = 0;
628					ifinfo->state = IFS_IDLE;
629				}
630				break;
631			}
632			rtsol_timer_update(ifinfo);
633		}
634
635		if (timercmp(&ifinfo->expire, &rtsol_timer, <))
636			rtsol_timer = ifinfo->expire;
637	}
638
639	if (timercmp(&rtsol_timer, &tm_max, ==)) {
640		warnmsg(LOG_DEBUG, __func__, "there is no timer");
641		return(NULL);
642	} else if (timercmp(&rtsol_timer, &now, <))
643		/* this may occur when the interval is too small */
644		returnval.tv_sec = returnval.tv_usec = 0;
645	else
646		timersub(&rtsol_timer, &now, &returnval);
647
648	if (dflag > 1)
649		warnmsg(LOG_DEBUG, __func__, "New timer is %ld:%08ld",
650		    (long)returnval.tv_sec, (long)returnval.tv_usec);
651
652	return(&returnval);
653}
654
655void
656rtsol_timer_update(struct ifinfo *ifinfo)
657{
658#define MILLION 1000000
659#define DADRETRY 10		/* XXX: adhoc */
660	long interval;
661	struct timeval now;
662
663	bzero(&ifinfo->timer, sizeof(ifinfo->timer));
664
665	switch (ifinfo->state) {
666	case IFS_DOWN:
667	case IFS_TENTATIVE:
668		if (++ifinfo->dadcount > DADRETRY) {
669			ifinfo->dadcount = 0;
670			ifinfo->timer.tv_sec = PROBE_INTERVAL;
671		} else
672			ifinfo->timer.tv_sec = 1;
673		break;
674	case IFS_IDLE:
675		if (mobile_node) {
676			/* XXX should be configurable */
677			ifinfo->timer.tv_sec = 3;
678		}
679		else
680			ifinfo->timer = tm_max;	/* stop timer(valid?) */
681		break;
682	case IFS_DELAY:
683#ifndef HAVE_ARC4RANDOM
684		interval = random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
685#else
686		interval = arc4random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
687#endif
688		ifinfo->timer.tv_sec = interval / MILLION;
689		ifinfo->timer.tv_usec = interval % MILLION;
690		break;
691	case IFS_PROBE:
692		if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
693			ifinfo->timer.tv_sec = RTR_SOLICITATION_INTERVAL;
694		else {
695			/*
696			 * After sending MAX_RTR_SOLICITATIONS solicitations,
697			 * we're just waiting for possible replies; there
698			 * will be no more solicatation.  Thus, we change
699			 * the timer value to MAX_RTR_SOLICITATION_DELAY based
700			 * on RFC 2461, Section 6.3.7.
701			 */
702			ifinfo->timer.tv_sec = MAX_RTR_SOLICITATION_DELAY;
703		}
704		break;
705	default:
706		warnmsg(LOG_ERR, __func__,
707		    "illegal interface state(%d) on %s",
708		    ifinfo->state, ifinfo->ifname);
709		return;
710	}
711
712	/* reset the timer */
713	if (timercmp(&ifinfo->timer, &tm_max, ==)) {
714		ifinfo->expire = tm_max;
715		warnmsg(LOG_DEBUG, __func__,
716		    "stop timer for %s", ifinfo->ifname);
717	} else {
718		gettimeofday(&now, NULL);
719		timeradd(&now, &ifinfo->timer, &ifinfo->expire);
720
721		if (dflag > 1)
722			warnmsg(LOG_DEBUG, __func__,
723			    "set timer for %s to %d:%d", ifinfo->ifname,
724			    (int)ifinfo->timer.tv_sec,
725			    (int)ifinfo->timer.tv_usec);
726	}
727
728#undef MILLION
729}
730
731/* timer related utility functions */
732#define MILLION 1000000
733
734#ifndef SMALL
735static void
736rtsold_set_dump_file(int sig)
737{
738	do_dump = 1;
739}
740#endif
741
742static void
743usage(char *progname)
744{
745	if (progname && progname[strlen(progname) - 1] != 'd') {
746		fprintf(stderr, "usage: rtsol [-dDF] interfaces...\n");
747		fprintf(stderr, "usage: rtsol [-dDF] -a\n");
748	} else {
749		fprintf(stderr, "usage: rtsold [-adDfFm1] interfaces...\n");
750		fprintf(stderr, "usage: rtsold [-dDfFm1] -a\n");
751	}
752	exit(1);
753}
754
755void
756#if __STDC__
757warnmsg(int priority, const char *func, const char *msg, ...)
758#else
759warnmsg(priority, func, msg, va_alist)
760	int priority;
761	const char *func;
762	const char *msg;
763	va_dcl
764#endif
765{
766	va_list ap;
767	char buf[BUFSIZ];
768
769	va_start(ap, msg);
770	if (fflag) {
771		if (priority <= log_upto) {
772			(void)vfprintf(stderr, msg, ap);
773			(void)fprintf(stderr, "\n");
774		}
775	} else {
776		snprintf(buf, sizeof(buf), "<%s> %s", func, msg);
777		msg = buf;
778		vsyslog(priority, msg, ap);
779	}
780	va_end(ap);
781}
782
783/*
784 * return a list of interfaces which is suitable to sending an RS.
785 */
786char **
787autoifprobe(void)
788{
789	static char **argv = NULL;
790	static int n = 0;
791	char **a;
792	int i, found;
793	struct ifaddrs *ifap, *ifa, *target;
794
795	/* initialize */
796	while (n--)
797		free(argv[n]);
798	if (argv) {
799		free(argv);
800		argv = NULL;
801	}
802	n = 0;
803
804	if (getifaddrs(&ifap) != 0)
805		return NULL;
806
807	target = NULL;
808	/* find an ethernet */
809	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
810		if ((ifa->ifa_flags & IFF_UP) == 0)
811			continue;
812		if ((ifa->ifa_flags & IFF_POINTOPOINT) != 0)
813			continue;
814		if ((ifa->ifa_flags & IFF_LOOPBACK) != 0)
815			continue;
816		if ((ifa->ifa_flags & IFF_MULTICAST) == 0)
817			continue;
818
819		if (ifa->ifa_addr->sa_family != AF_INET6)
820			continue;
821
822		found = 0;
823		for (i = 0; i < n; i++) {
824			if (strcmp(argv[i], ifa->ifa_name) == 0) {
825				found++;
826				break;
827			}
828		}
829		if (found)
830			continue;
831
832		/* if we find multiple candidates, just warn. */
833		if (n != 0 && dflag > 1)
834			warnx("multiple interfaces found");
835
836		a = (char **)realloc(argv, (n + 1) * sizeof(char **));
837		if (a == NULL)
838			err(1, "realloc");
839		argv = a;
840		argv[n] = strdup(ifa->ifa_name);
841		if (!argv[n])
842			err(1, "malloc");
843		n++;
844		argv[n] = NULL;
845	}
846
847	if (n) {
848		a = (char **)realloc(argv, (n + 1) * sizeof(char **));
849		if (a == NULL)
850			err(1, "realloc");
851		argv = a;
852		argv[n] = NULL;
853
854		if (dflag > 0) {
855			for (i = 0; i < n; i++)
856				warnx("probing %s", argv[i]);
857		}
858	}
859	freeifaddrs(ifap);
860	return argv;
861}
862