xref: /dragonfly/usr.sbin/rtsold/rtsold.c (revision 0dace59e) 
1 /*	$KAME: rtsold.c,v 1.31 2001/05/22 06:03:06 jinmei 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: src/usr.sbin/rtsold/rtsold.c,v 1.1.2.4 2002/04/04 11:07:19 ume Exp $
32  * $DragonFly: src/usr.sbin/rtsold/rtsold.c,v 1.7 2005/12/05 00:56:37 swildner Exp $
33  */
34 
35 #include <sys/types.h>
36 #include <sys/time.h>
37 #include <sys/socket.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 #include "rtsold.h"
56 
57 struct ifinfo *iflist;
58 struct timeval tm_max =	{0x7fffffff, 0x7fffffff};
59 int aflag = 0;
60 int dflag = 0;
61 static int log_upto = 999;
62 static int fflag = 0;
63 
64 /* protocol constatns */
65 #define MAX_RTR_SOLICITATION_DELAY	1 /* second */
66 #define RTR_SOLICITATION_INTERVAL	4 /* seconds */
67 #define MAX_RTR_SOLICITATIONS		3 /* times */
68 
69 /* implementation dependent constants */
70 #define PROBE_INTERVAL 60	/* secondes XXX: should be configurable */
71 
72 /* utility macros */
73 /* a < b */
74 #define TIMEVAL_LT(a, b) (((a).tv_sec < (b).tv_sec) ||\
75 			  (((a).tv_sec == (b).tv_sec) && \
76 			    ((a).tv_usec < (b).tv_usec)))
77 
78 /* a <= b */
79 #define TIMEVAL_LEQ(a, b) (((a).tv_sec < (b).tv_sec) ||\
80 			   (((a).tv_sec == (b).tv_sec) &&\
81  			    ((a).tv_usec <= (b).tv_usec)))
82 
83 /* a == b */
84 #define TIMEVAL_EQ(a, b) (((a).tv_sec==(b).tv_sec) && ((a).tv_usec==(b).tv_usec))
85 
86 int main(int argc, char *argv[]);
87 
88 /* static variables and functions */
89 static int mobile_node = 0;
90 static int do_dump;
91 /*
92  * XXX: the following two values should be configurable
93  */
94 static const char *dumpfilename = "/var/run/rtsold.dump";
95 static const char *pidfilename = "/var/run/rtsold.pid";
96 
97 static int ifconfig(char *ifname);
98 #if 0
99 static int ifreconfig(char *ifname);
100 #endif
101 static int make_packet(struct ifinfo *ifinfo);
102 static struct timeval *rtsol_check_timer(void);
103 static void TIMEVAL_ADD(struct timeval *a, struct timeval *b,
104 			     struct timeval *result);
105 static void TIMEVAL_SUB(struct timeval *a, struct timeval *b,
106 			     struct timeval *result);
107 
108 static void rtsold_set_dump_file(int);
109 static void usage(char *progname);
110 static char **autoifprobe(void);
111 
112 int
113 main(int argc, char *argv[])
114 {
115 	int s, rtsock, maxfd, ch;
116 	int once = 0;
117 	struct timeval *timeout;
118 	struct fd_set fdset;
119 	char *argv0;
120 	const char *opts;
121 
122 	/*
123 	 * Initialization
124 	 */
125 	argv0 = argv[0];
126 
127 	/* get option */
128 	if (argv0 && argv0[strlen(argv0) - 1] != 'd') {
129 		fflag = 1;
130 		once = 1;
131 		opts = "adD";
132 	} else
133 		opts = "adDfm1";
134 
135 	while ((ch = getopt(argc, argv, opts)) != -1) {
136 		switch (ch) {
137 		case 'a':
138 			aflag = 1;
139 			break;
140 		case 'd':
141 			dflag = 1;
142 			break;
143 		case 'D':
144 			dflag = 2;
145 			break;
146 		case 'f':
147 			fflag = 1;
148 			break;
149 		case 'm':
150 			mobile_node = 1;
151 			break;
152 		case '1':
153 			once = 1;
154 			break;
155 		default:
156 			usage(argv0);
157 			/*NOTREACHED*/
158 		}
159 	}
160 	argc -= optind;
161 	argv += optind;
162 
163 	if (aflag) {
164 		int i;
165 
166 		if (argc != 0) {
167 			usage(argv0);
168 			/*NOTREACHED*/
169 		}
170 
171 		argv = autoifprobe();
172 		if (!argv) {
173 			errx(1, "could not autoprobe interface");
174 			/*NOTREACHED*/
175 		}
176 
177 		for (i = 0; argv[i]; i++)
178 			;
179 		argc = i;
180 	}
181 	if (argc == 0) {
182 		usage(argv0);
183 		/*NOTREACHED*/
184 	}
185 
186 	/* set log level */
187 	if (dflag == 0)
188 		log_upto = LOG_NOTICE;
189 	if (!fflag) {
190 		char *ident;
191 		ident = strrchr(argv0, '/');
192 		if (!ident)
193 			ident = argv0;
194 		else
195 			ident++;
196 		openlog(ident, LOG_NDELAY|LOG_PID, LOG_DAEMON);
197 		if (log_upto >= 0)
198 			setlogmask(LOG_UPTO(log_upto));
199 	}
200 
201 #ifndef HAVE_ARC4RANDOM
202 	/* random value initilization */
203 	srandom((u_long)time(NULL));
204 #endif
205 
206 	/* warn if accept_rtadv is down */
207 	if (!getinet6sysctl(IPV6CTL_ACCEPT_RTADV))
208 		warnx("kernel is configured not to accept RAs");
209 	/* warn if forwarding is up */
210 	if (getinet6sysctl(IPV6CTL_FORWARDING))
211 		warnx("kernel is configured as a router, not a host");
212 
213 	/* initialization to dump internal status to a file */
214 	if (signal(SIGUSR1, rtsold_set_dump_file) == SIG_ERR) {
215 		errx(1, "failed to set signal for dump status");
216 		/*NOTREACHED*/
217 	}
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 		errx(1, "failed to open a socket");
226 		/*NOTREACHED*/
227 	}
228 	maxfd = s;
229 	if ((rtsock = rtsock_open()) < 0) {
230 		errx(1, "failed to open a socket");
231 		/*NOTREACHED*/
232 	}
233 	if (rtsock > maxfd)
234 		maxfd = rtsock;
235 
236 	/* configuration per interface */
237 	if (ifinit()) {
238 		errx(1, "failed to initilizatoin interfaces");
239 		/*NOTREACHED*/
240 	}
241 	while (argc--) {
242 		if (ifconfig(*argv)) {
243 			errx(1, "failed to initialize %s", *argv);
244 			/*NOTREACHED*/
245 		}
246 		argv++;
247 	}
248 
249 	/* setup for probing default routers */
250 	if (probe_init()) {
251 		errx(1, "failed to setup for probing routers");
252 		/*NOTREACHED*/
253 	}
254 
255 	if (!fflag)
256 		daemon(0, 0);		/* act as a daemon */
257 
258 	/* dump the current pid */
259 	if (!once) {
260 		pid_t pid = getpid();
261 		FILE *fp;
262 
263 		if ((fp = fopen(pidfilename, "w")) == NULL)
264 			warnmsg(LOG_ERR, __func__,
265 				"failed to open a log file(%s): %s",
266 				pidfilename, strerror(errno));
267 		else {
268 			fprintf(fp, "%d\n", pid);
269 			fclose(fp);
270 		}
271 	}
272 
273 	FD_ZERO(&fdset);
274 	FD_SET(s, &fdset);
275 	FD_SET(rtsock, &fdset);
276 	while (1) {		/* main loop */
277 		int e;
278 		struct fd_set select_fd = fdset;
279 
280 		if (do_dump) {	/* SIGUSR1 */
281 			do_dump = 0;
282 			rtsold_dump_file(dumpfilename);
283 		}
284 
285 		timeout = rtsol_check_timer();
286 
287 		if (once) {
288 			struct ifinfo *ifi;
289 
290 			/* if we have no timeout, we are done (or failed) */
291 			if (timeout == NULL)
292 				break;
293 
294 			/* if all interfaces have got RA packet, we are done */
295 			for (ifi = iflist; ifi; ifi = ifi->next) {
296 				if (ifi->state != IFS_DOWN && ifi->racnt == 0)
297 					break;
298 			}
299 			if (ifi == NULL)
300 				break;
301 		}
302 		e = select(maxfd + 1, &select_fd, NULL, NULL, timeout);
303 		if (e < 1) {
304 			if (e < 0 && errno != EINTR) {
305 				warnmsg(LOG_ERR, __func__, "select: %s",
306 				       strerror(errno));
307 			}
308 			continue;
309 		}
310 
311 		/* packet reception */
312 		if (FD_ISSET(rtsock, &select_fd))
313 			rtsock_input(rtsock);
314 		if (FD_ISSET(s, &select_fd))
315 			rtsol_input(s);
316 	}
317 	/* NOTREACHED */
318 
319 	return 0;
320 }
321 
322 static int
323 ifconfig(char *ifname)
324 {
325 	struct ifinfo *ifinfo;
326 	struct sockaddr_dl *sdl;
327 	int flags;
328 
329 	if ((sdl = if_nametosdl(ifname)) == NULL) {
330 		warnmsg(LOG_ERR, __func__,
331 		       "failed to get link layer information for %s", ifname);
332 		return(-1);
333 	}
334 	if (find_ifinfo(sdl->sdl_index)) {
335 		warnmsg(LOG_ERR, __func__,
336 			"interface %s was already configured", ifname);
337 		free(sdl);
338 		return(-1);
339 	}
340 
341 	if ((ifinfo = malloc(sizeof(*ifinfo))) == NULL) {
342 		warnmsg(LOG_ERR, __func__, "memory allocation failed");
343 		free(sdl);
344 		return(-1);
345 	}
346 	memset(ifinfo, 0, sizeof(*ifinfo));
347 	ifinfo->sdl = sdl;
348 
349 	strncpy(ifinfo->ifname, ifname, sizeof(ifinfo->ifname));
350 
351 	/* construct a router solicitation message */
352 	if (make_packet(ifinfo))
353 		goto bad;
354 
355 	/*
356 	 * check if the interface is available.
357 	 * also check if SIOCGIFMEDIA ioctl is OK on the interface.
358 	 */
359 	ifinfo->mediareqok = 1;
360 	ifinfo->active = interface_status(ifinfo);
361 	if (!ifinfo->mediareqok) {
362 		/*
363 		 * probe routers periodically even if the link status
364 		 * does not change.
365 		 */
366 		ifinfo->probeinterval = PROBE_INTERVAL;
367 	}
368 
369 	/* activate interface: interface_up returns 0 on success */
370 	flags = interface_up(ifinfo->ifname);
371 	if (flags == 0)
372 		ifinfo->state = IFS_DELAY;
373 	else if (flags == IFS_TENTATIVE)
374 		ifinfo->state = IFS_TENTATIVE;
375 	else
376 		ifinfo->state = IFS_DOWN;
377 
378 	rtsol_timer_update(ifinfo);
379 
380 	/* link into chain */
381 	if (iflist)
382 		ifinfo->next = iflist;
383 	iflist = ifinfo;
384 
385 	return(0);
386 
387   bad:
388 	free(ifinfo->sdl);
389 	free(ifinfo);
390 	return(-1);
391 }
392 
393 #if 0
394 static int
395 ifreconfig(char *ifname)
396 {
397 	struct ifinfo *ifi, *prev;
398 	int rv;
399 
400 	prev = NULL;
401 	for (ifi = iflist; ifi; ifi = ifi->next) {
402 		if (strncmp(ifi->ifname, ifname, sizeof(ifi->ifname)) == 0)
403 			break;
404 		prev = ifi;
405 	}
406 	prev->next = ifi->next;
407 
408 	rv = ifconfig(ifname);
409 
410 	/* reclaim it after ifconfig() in case ifname is pointer inside ifi */
411 	if (ifi->rs_data)
412 		free(ifi->rs_data);
413 	free(ifi->sdl);
414 	free(ifi);
415 
416 	return rv;
417 }
418 #endif
419 
420 struct ifinfo *
421 find_ifinfo(int ifindex)
422 {
423 	struct ifinfo *ifi;
424 
425 	for (ifi = iflist; ifi; ifi = ifi->next)
426 		if (ifi->sdl->sdl_index == ifindex)
427 			return(ifi);
428 
429 	return(NULL);
430 }
431 
432 static int
433 make_packet(struct ifinfo *ifinfo)
434 {
435 	char *buf;
436 	struct nd_router_solicit *rs;
437 	size_t packlen = sizeof(struct nd_router_solicit), lladdroptlen = 0;
438 
439 	if ((lladdroptlen = lladdropt_length(ifinfo->sdl)) == 0) {
440 		warnmsg(LOG_INFO, __func__,
441 			"link-layer address option has null length"
442 		       " on %s. Treat as not included.", ifinfo->ifname);
443 	}
444 	packlen += lladdroptlen;
445 	ifinfo->rs_datalen = packlen;
446 
447 	/* allocate buffer */
448 	if ((buf = malloc(packlen)) == NULL) {
449 		warnmsg(LOG_ERR, __func__,
450 			"memory allocation failed for %s", ifinfo->ifname);
451 		return(-1);
452 	}
453 	ifinfo->rs_data = buf;
454 
455 	/* fill in the message */
456 	rs = (struct nd_router_solicit *)buf;
457 	rs->nd_rs_type = ND_ROUTER_SOLICIT;
458 	rs->nd_rs_code = 0;
459 	rs->nd_rs_cksum = 0;
460 	rs->nd_rs_reserved = 0;
461 	buf += sizeof(*rs);
462 
463 	/* fill in source link-layer address option */
464 	if (lladdroptlen)
465 		lladdropt_fill(ifinfo->sdl, (struct nd_opt_hdr *)buf);
466 
467 	return(0);
468 }
469 
470 static struct timeval *
471 rtsol_check_timer(void)
472 {
473 	static struct timeval returnval;
474 	struct timeval now, rtsol_timer;
475 	struct ifinfo *ifinfo;
476 	int flags;
477 
478 	gettimeofday(&now, NULL);
479 
480 	rtsol_timer = tm_max;
481 
482 	for (ifinfo = iflist; ifinfo; ifinfo = ifinfo->next) {
483 		if (TIMEVAL_LEQ(ifinfo->expire, now)) {
484 			if (dflag > 1)
485 				warnmsg(LOG_DEBUG, __func__,
486 					"timer expiration on %s, "
487 				       "state = %d", ifinfo->ifname,
488 				       ifinfo->state);
489 
490 			switch (ifinfo->state) {
491 			case IFS_DOWN:
492 			case IFS_TENTATIVE:
493 				/* interface_up returns 0 on success */
494 				flags = interface_up(ifinfo->ifname);
495 				if (flags == 0)
496 					ifinfo->state = IFS_DELAY;
497 				else if (flags == IFS_TENTATIVE)
498 					ifinfo->state = IFS_TENTATIVE;
499 				else
500 					ifinfo->state = IFS_DOWN;
501 				break;
502 			case IFS_IDLE:
503 			{
504 				int oldstatus = ifinfo->active;
505 				int probe = 0;
506 
507 				ifinfo->active =
508 					interface_status(ifinfo);
509 
510 				if (oldstatus != ifinfo->active) {
511 					warnmsg(LOG_DEBUG, __func__,
512 						"%s status is changed"
513 						" from %d to %d",
514 						ifinfo->ifname,
515 						oldstatus, ifinfo->active);
516 					probe = 1;
517 					ifinfo->state = IFS_DELAY;
518 				}
519 				else if (ifinfo->probeinterval &&
520 					 (ifinfo->probetimer -=
521 					  ifinfo->timer.tv_sec) <= 0) {
522 					/* probe timer expired */
523 					ifinfo->probetimer =
524 						ifinfo->probeinterval;
525 					probe = 1;
526 					ifinfo->state = IFS_PROBE;
527 				}
528 
529 				if (probe && mobile_node)
530 					defrouter_probe(ifinfo->sdl->sdl_index);
531 				break;
532 			}
533 			case IFS_DELAY:
534 				ifinfo->state = IFS_PROBE;
535 				sendpacket(ifinfo);
536 				break;
537 			case IFS_PROBE:
538 				if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
539 					sendpacket(ifinfo);
540 				else {
541 					warnmsg(LOG_INFO, __func__,
542 						"No answer "
543 						"after sending %d RSs",
544 						ifinfo->probes);
545 					ifinfo->probes = 0;
546 					ifinfo->state = IFS_IDLE;
547 				}
548 				break;
549 			}
550 			rtsol_timer_update(ifinfo);
551 		}
552 
553 		if (TIMEVAL_LT(ifinfo->expire, rtsol_timer))
554 			rtsol_timer = ifinfo->expire;
555 	}
556 
557 	if (TIMEVAL_EQ(rtsol_timer, tm_max)) {
558 		warnmsg(LOG_DEBUG, __func__, "there is no timer");
559 		return(NULL);
560 	}
561 	else if (TIMEVAL_LT(rtsol_timer, now))
562 		/* this may occur when the interval is too small */
563 		returnval.tv_sec = returnval.tv_usec = 0;
564 	else
565 		TIMEVAL_SUB(&rtsol_timer, &now, &returnval);
566 
567 	if (dflag > 1)
568 		warnmsg(LOG_DEBUG, __func__, "New timer is %ld:%08ld",
569 			(long)returnval.tv_sec, (long)returnval.tv_usec);
570 
571 	return(&returnval);
572 }
573 
574 void
575 rtsol_timer_update(struct ifinfo *ifinfo)
576 {
577 #define MILLION 1000000
578 #define DADRETRY 10		/* XXX: adhoc */
579 	long interval;
580 	struct timeval now;
581 
582 	bzero(&ifinfo->timer, sizeof(ifinfo->timer));
583 
584 	switch (ifinfo->state) {
585 	case IFS_DOWN:
586 	case IFS_TENTATIVE:
587 		if (++ifinfo->dadcount > DADRETRY) {
588 			ifinfo->dadcount = 0;
589 			ifinfo->timer.tv_sec = PROBE_INTERVAL;
590 		}
591 		else
592 			ifinfo->timer.tv_sec = 1;
593 		break;
594 	case IFS_IDLE:
595 		if (mobile_node) {
596 			/* XXX should be configurable */
597 			ifinfo->timer.tv_sec = 3;
598 		}
599 		else
600 			ifinfo->timer = tm_max;	/* stop timer(valid?) */
601 		break;
602 	case IFS_DELAY:
603 #ifndef HAVE_ARC4RANDOM
604 		interval = random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
605 #else
606 		interval = arc4random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
607 #endif
608 		ifinfo->timer.tv_sec = interval / MILLION;
609 		ifinfo->timer.tv_usec = interval % MILLION;
610 		break;
611 	case IFS_PROBE:
612 		if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
613 			ifinfo->timer.tv_sec = RTR_SOLICITATION_INTERVAL;
614 		else {
615 			/*
616 			 * After sending MAX_RTR_SOLICITATIONS solicitations,
617 			 * we're just waiting for possible replies; there
618 			 * will be no more solicatation.  Thus, we change
619 			 * the timer value to MAX_RTR_SOLICITATION_DELAY based
620 			 * on RFC 2461, Section 6.3.7.
621 			 */
622 			ifinfo->timer.tv_sec = MAX_RTR_SOLICITATION_DELAY;
623 		}
624 		break;
625 	default:
626 		warnmsg(LOG_ERR, __func__,
627 			"illegal interface state(%d) on %s",
628 			ifinfo->state, ifinfo->ifname);
629 		return;
630 	}
631 
632 	/* reset the timer */
633 	if (TIMEVAL_EQ(ifinfo->timer, tm_max)) {
634 		ifinfo->expire = tm_max;
635 		warnmsg(LOG_DEBUG, __func__,
636 			"stop timer for %s", ifinfo->ifname);
637 	}
638 	else {
639 		gettimeofday(&now, NULL);
640 		TIMEVAL_ADD(&now, &ifinfo->timer, &ifinfo->expire);
641 
642 		if (dflag > 1)
643 			warnmsg(LOG_DEBUG, __func__,
644 				"set timer for %s to %d:%d", ifinfo->ifname,
645 			       (int)ifinfo->timer.tv_sec,
646 			       (int)ifinfo->timer.tv_usec);
647 	}
648 
649 #undef MILLION
650 }
651 
652 /* timer related utility functions */
653 #define MILLION 1000000
654 
655 /* result = a + b */
656 static void
657 TIMEVAL_ADD(struct timeval *a, struct timeval *b, struct timeval *result)
658 {
659 	long l;
660 
661 	if ((l = a->tv_usec + b->tv_usec) < MILLION) {
662 		result->tv_usec = l;
663 		result->tv_sec = a->tv_sec + b->tv_sec;
664 	}
665 	else {
666 		result->tv_usec = l - MILLION;
667 		result->tv_sec = a->tv_sec + b->tv_sec + 1;
668 	}
669 }
670 
671 /*
672  * result = a - b
673  * XXX: this function assumes that a >= b.
674  */
675 void
676 TIMEVAL_SUB(struct timeval *a, struct timeval *b, struct timeval *result)
677 {
678 	long l;
679 
680 	if ((l = a->tv_usec - b->tv_usec) >= 0) {
681 		result->tv_usec = l;
682 		result->tv_sec = a->tv_sec - b->tv_sec;
683 	}
684 	else {
685 		result->tv_usec = MILLION + l;
686 		result->tv_sec = a->tv_sec - b->tv_sec - 1;
687 	}
688 }
689 
690 static void
691 rtsold_set_dump_file(int signo __unused)
692 {
693 	do_dump = 1;
694 }
695 
696 static void
697 usage(char *progname)
698 {
699 	if (progname && progname[strlen(progname) - 1] != 'd') {
700 		fprintf(stderr, "usage: rtsol [-dD] interfaces...\n");
701 		fprintf(stderr, "usage: rtsol [-dD] -a\n");
702 	} else {
703 		fprintf(stderr, "usage: rtsold [-adDfm1] interfaces...\n");
704 		fprintf(stderr, "usage: rtsold [-dDfm1] -a\n");
705 	}
706 	exit(1);
707 }
708 
709 void
710 warnmsg(int priority, const char *func, const char *msg, ...)
711 {
712 	va_list ap;
713 	char buf[BUFSIZ];
714 
715 	va_start(ap, msg);
716 	if (fflag) {
717 		if (priority <= log_upto) {
718 			vfprintf(stderr, msg, ap);
719 			fprintf(stderr, "\n");
720 		}
721 	} else {
722 		snprintf(buf, sizeof(buf), "<%s> %s", func, msg);
723 		msg = buf;
724 		vsyslog(priority, msg, ap);
725 	}
726 	va_end(ap);
727 }
728 
729 static char **
730 autoifprobe(void)
731 {
732 #ifndef HAVE_GETIFADDRS
733 	errx(1, "-a is not available with the configuration");
734 #else
735 	static char ifname[IFNAMSIZ + 1];
736 	static char *argv[2];
737 	struct ifaddrs *ifap, *ifa, *target;
738 
739 	if (getifaddrs(&ifap) != 0)
740 		return NULL;
741 
742 	target = NULL;
743 	/* find an ethernet */
744 	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
745 		if ((ifa->ifa_flags & IFF_UP) == 0)
746 			continue;
747 		if ((ifa->ifa_flags & IFF_POINTOPOINT) != 0)
748 			continue;
749 		if ((ifa->ifa_flags & IFF_LOOPBACK) != 0)
750 			continue;
751 		if ((ifa->ifa_flags & IFF_MULTICAST) == 0)
752 			continue;
753 
754 		if (ifa->ifa_addr->sa_family != AF_INET6)
755 			continue;
756 
757 		if (target && strcmp(target->ifa_name, ifa->ifa_name) == 0)
758 			continue;
759 
760 		if (!target)
761 			target = ifa;
762 		else {
763 			/* if we find multiple candidates, failure. */
764 			if (dflag > 1)
765 				warnx("multiple interfaces found");
766 			target = NULL;
767 			break;
768 		}
769 	}
770 
771 	if (target) {
772 		strncpy(ifname, target->ifa_name, sizeof(ifname) - 1);
773 		ifname[sizeof(ifname) - 1] = '\0';
774 		argv[0] = ifname;
775 		argv[1] = NULL;
776 
777 		if (dflag > 0)
778 			warnx("probing %s", argv[0]);
779 	}
780 	freeifaddrs(ifap);
781 	if (target)
782 		return argv;
783 	else
784 		return NULL;
785 #endif
786 }
787