xref: /freebsd/usr.sbin/rtsold/rtsold.c (revision c17d43407fe04133a94055b0dbc7ea8965654a9f) 
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  * $FreeBSD$
32  */
33 
34 #include <sys/types.h>
35 #include <sys/time.h>
36 #include <sys/socket.h>
37 
38 #include <net/if.h>
39 #include <net/if_dl.h>
40 
41 #include <netinet/in.h>
42 #include <netinet/icmp6.h>
43 
44 #include <signal.h>
45 #include <unistd.h>
46 #include <syslog.h>
47 #include <string.h>
48 #include <stdlib.h>
49 #include <stdio.h>
50 #include <errno.h>
51 #include <err.h>
52 #include <stdarg.h>
53 #include <ifaddrs.h>
54 #include "rtsold.h"
55 
56 struct ifinfo *iflist;
57 struct timeval tm_max =	{0x7fffffff, 0x7fffffff};
58 int aflag = 0;
59 int dflag = 0;
60 static int log_upto = 999;
61 static int fflag = 0;
62 
63 /* protocol constatns */
64 #define MAX_RTR_SOLICITATION_DELAY	1 /* second */
65 #define RTR_SOLICITATION_INTERVAL	4 /* seconds */
66 #define MAX_RTR_SOLICITATIONS		3 /* times */
67 
68 /* implementation dependent constants */
69 #define PROBE_INTERVAL 60	/* secondes XXX: should be configurable */
70 
71 /* utility macros */
72 /* a < b */
73 #define TIMEVAL_LT(a, b) (((a).tv_sec < (b).tv_sec) ||\
74 			  (((a).tv_sec == (b).tv_sec) && \
75 			    ((a).tv_usec < (b).tv_usec)))
76 
77 /* a <= b */
78 #define TIMEVAL_LEQ(a, b) (((a).tv_sec < (b).tv_sec) ||\
79 			   (((a).tv_sec == (b).tv_sec) &&\
80  			    ((a).tv_usec <= (b).tv_usec)))
81 
82 /* a == b */
83 #define TIMEVAL_EQ(a, b) (((a).tv_sec==(b).tv_sec) && ((a).tv_usec==(b).tv_usec))
84 
85 int main __P((int argc, char *argv[]));
86 
87 /* static variables and functions */
88 static int mobile_node = 0;
89 static int do_dump;
90 static char *dumpfilename = "/var/run/rtsold.dump"; /* XXX: should be configurable */
91 static char *pidfilename = "/var/run/rtsold.pid"; /* should be configurable */
92 
93 static int ifconfig __P((char *ifname));
94 #if 0
95 static int ifreconfig __P((char *ifname));
96 #endif
97 static int make_packet __P((struct ifinfo *ifinfo));
98 static struct timeval *rtsol_check_timer __P((void));
99 static void TIMEVAL_ADD __P((struct timeval *a, struct timeval *b,
100 			     struct timeval *result));
101 static void TIMEVAL_SUB __P((struct timeval *a, struct timeval *b,
102 			     struct timeval *result));
103 
104 static void rtsold_set_dump_file __P((void));
105 static void usage __P((char *progname));
106 static char **autoifprobe __P((void));
107 
108 int
109 main(argc, argv)
110 	int argc;
111 	char *argv[];
112 {
113 	int s, rtsock, maxfd, ch;
114 	int once = 0;
115 	struct timeval *timeout;
116 	struct fd_set fdset;
117 	char *argv0;
118 	char *opts;
119 
120 	/*
121 	 * Initialization
122 	 */
123 	argv0 = argv[0];
124 
125 	/* get option */
126 	if (argv0 && argv0[strlen(argv0) - 1] != 'd') {
127 		fflag = 1;
128 		once = 1;
129 		opts = "adD";
130 	} else
131 		opts = "adDfm1";
132 
133 	while ((ch = getopt(argc, argv, opts)) != -1) {
134 		switch (ch) {
135 		case 'a':
136 			aflag = 1;
137 			break;
138 		case 'd':
139 			dflag = 1;
140 			break;
141 		case 'D':
142 			dflag = 2;
143 			break;
144 		case 'f':
145 			fflag = 1;
146 			break;
147 		case 'm':
148 			mobile_node = 1;
149 			break;
150 		case '1':
151 			once = 1;
152 			break;
153 		default:
154 			usage(argv0);
155 			/*NOTREACHED*/
156 		}
157 	}
158 	argc -= optind;
159 	argv += optind;
160 
161 	if (aflag) {
162 		int i;
163 
164 		if (argc != 0) {
165 			usage(argv0);
166 			/*NOTREACHED*/
167 		}
168 
169 		argv = autoifprobe();
170 		if (!argv) {
171 			errx(1, "could not autoprobe interface");
172 			/*NOTREACHED*/
173 		}
174 
175 		for (i = 0; argv[i]; i++)
176 			;
177 		argc = i;
178 	}
179 	if (argc == 0) {
180 		usage(argv0);
181 		/*NOTREACHED*/
182 	}
183 
184 	/* set log level */
185 	if (dflag == 0)
186 		log_upto = LOG_NOTICE;
187 	if (!fflag) {
188 		char *ident;
189 		ident = strrchr(argv0, '/');
190 		if (!ident)
191 			ident = argv0;
192 		else
193 			ident++;
194 		openlog(ident, LOG_NDELAY|LOG_PID, LOG_DAEMON);
195 		if (log_upto >= 0)
196 			setlogmask(LOG_UPTO(log_upto));
197 	}
198 
199 #ifndef HAVE_ARC4RANDOM
200 	/* random value initilization */
201 	srandom((u_long)time(NULL));
202 #endif
203 
204 	/* warn if accept_rtadv is down */
205 	if (!getinet6sysctl(IPV6CTL_ACCEPT_RTADV))
206 		warnx("kernel is configured not to accept RAs");
207 	/* warn if forwarding is up */
208 	if (getinet6sysctl(IPV6CTL_FORWARDING))
209 		warnx("kernel is configured as a router, not a host");
210 
211 	/* initialization to dump internal status to a file */
212 	if (signal(SIGUSR1, (void *)rtsold_set_dump_file) < 0) {
213 		errx(1, "failed to set signal for dump status");
214 		/*NOTREACHED*/
215 	}
216 
217 	/*
218 	 * Open a socket for sending RS and receiving RA.
219 	 * This should be done before calling ifinit(), since the function
220 	 * uses the socket.
221 	 */
222 	if ((s = sockopen()) < 0) {
223 		errx(1, "failed to open a socket");
224 		/*NOTREACHED*/
225 	}
226 	maxfd = s;
227 	if ((rtsock = rtsock_open()) < 0) {
228 		errx(1, "failed to open a socket");
229 		/*NOTREACHED*/
230 	}
231 	if (rtsock > maxfd)
232 		maxfd = rtsock;
233 
234 	/* configuration per interface */
235 	if (ifinit()) {
236 		errx(1, "failed to initilizatoin interfaces");
237 		/*NOTREACHED*/
238 	}
239 	while (argc--) {
240 		if (ifconfig(*argv)) {
241 			errx(1, "failed to initialize %s", *argv);
242 			/*NOTREACHED*/
243 		}
244 		argv++;
245 	}
246 
247 	/* setup for probing default routers */
248 	if (probe_init()) {
249 		errx(1, "failed to setup for probing routers");
250 		/*NOTREACHED*/
251 	}
252 
253 	if (!fflag)
254 		daemon(0, 0);		/* act as a daemon */
255 
256 	/* dump the current pid */
257 	if (!once) {
258 		pid_t pid = getpid();
259 		FILE *fp;
260 
261 		if ((fp = fopen(pidfilename, "w")) == NULL)
262 			warnmsg(LOG_ERR, __FUNCTION__,
263 				"failed to open a log file(%s): %s",
264 				pidfilename, strerror(errno));
265 		else {
266 			fprintf(fp, "%d\n", pid);
267 			fclose(fp);
268 		}
269 	}
270 
271 	FD_ZERO(&fdset);
272 	FD_SET(s, &fdset);
273 	FD_SET(rtsock, &fdset);
274 	while (1) {		/* main loop */
275 		int e;
276 		struct fd_set select_fd = fdset;
277 
278 		if (do_dump) {	/* SIGUSR1 */
279 			do_dump = 0;
280 			rtsold_dump_file(dumpfilename);
281 		}
282 
283 		timeout = rtsol_check_timer();
284 
285 		if (once) {
286 			struct ifinfo *ifi;
287 
288 			/* if we have no timeout, we are done (or failed) */
289 			if (timeout == NULL)
290 				break;
291 
292 			/* if all interfaces have got RA packet, we are done */
293 			for (ifi = iflist; ifi; ifi = ifi->next) {
294 				if (ifi->state != IFS_DOWN && ifi->racnt == 0)
295 					break;
296 			}
297 			if (ifi == NULL)
298 				break;
299 		}
300 		e = select(maxfd + 1, &select_fd, NULL, NULL, timeout);
301 		if (e < 1) {
302 			if (e < 0 && errno != EINTR) {
303 				warnmsg(LOG_ERR, __FUNCTION__, "select: %s",
304 				       strerror(errno));
305 			}
306 			continue;
307 		}
308 
309 		/* packet reception */
310 		if (FD_ISSET(rtsock, &select_fd))
311 			rtsock_input(rtsock);
312 		if (FD_ISSET(s, &select_fd))
313 			rtsol_input(s);
314 	}
315 	/* NOTREACHED */
316 
317 	return 0;
318 }
319 
320 static int
321 ifconfig(char *ifname)
322 {
323 	struct ifinfo *ifinfo;
324 	struct sockaddr_dl *sdl;
325 	int flags;
326 
327 	if ((sdl = if_nametosdl(ifname)) == NULL) {
328 		warnmsg(LOG_ERR, __FUNCTION__,
329 		       "failed to get link layer information for %s", ifname);
330 		return(-1);
331 	}
332 	if (find_ifinfo(sdl->sdl_index)) {
333 		warnmsg(LOG_ERR, __FUNCTION__,
334 			"interface %s was already cofigured", ifname);
335 		free(sdl);
336 		return(-1);
337 	}
338 
339 	if ((ifinfo = malloc(sizeof(*ifinfo))) == NULL) {
340 		warnmsg(LOG_ERR, __FUNCTION__, "memory allocation failed");
341 		free(sdl);
342 		return(-1);
343 	}
344 	memset(ifinfo, 0, sizeof(*ifinfo));
345 	ifinfo->sdl = sdl;
346 
347 	strncpy(ifinfo->ifname, ifname, sizeof(ifinfo->ifname));
348 
349 	/* construct a router solicitation message */
350 	if (make_packet(ifinfo))
351 		goto bad;
352 
353 	/*
354 	 * check if the interface is available.
355 	 * also check if SIOCGIFMEDIA ioctl is OK on the interface.
356 	 */
357 	ifinfo->mediareqok = 1;
358 	ifinfo->active = interface_status(ifinfo);
359 	if (!ifinfo->mediareqok) {
360 		/*
361 		 * probe routers periodically even if the link status
362 		 * does not change.
363 		 */
364 		ifinfo->probeinterval = PROBE_INTERVAL;
365 	}
366 
367 	/* activate interface: interface_up returns 0 on success */
368 	flags = interface_up(ifinfo->ifname);
369 	if (flags == 0)
370 		ifinfo->state = IFS_DELAY;
371 	else if (flags == IFS_TENTATIVE)
372 		ifinfo->state = IFS_TENTATIVE;
373 	else
374 		ifinfo->state = IFS_DOWN;
375 
376 	rtsol_timer_update(ifinfo);
377 
378 	/* link into chain */
379 	if (iflist)
380 		ifinfo->next = iflist;
381 	iflist = ifinfo;
382 
383 	return(0);
384 
385   bad:
386 	free(ifinfo->sdl);
387 	free(ifinfo);
388 	return(-1);
389 }
390 
391 #if 0
392 static int
393 ifreconfig(char *ifname)
394 {
395 	struct ifinfo *ifi, *prev;
396 	int rv;
397 
398 	prev = NULL;
399 	for (ifi = iflist; ifi; ifi = ifi->next) {
400 		if (strncmp(ifi->ifname, ifname, sizeof(ifi->ifname)) == 0)
401 			break;
402 		prev = ifi;
403 	}
404 	prev->next = ifi->next;
405 
406 	rv = ifconfig(ifname);
407 
408 	/* reclaim it after ifconfig() in case ifname is pointer inside ifi */
409 	if (ifi->rs_data)
410 		free(ifi->rs_data);
411 	free(ifi->sdl);
412 	free(ifi);
413 
414 	return rv;
415 }
416 #endif
417 
418 struct ifinfo *
419 find_ifinfo(int ifindex)
420 {
421 	struct ifinfo *ifi;
422 
423 	for (ifi = iflist; ifi; ifi = ifi->next)
424 		if (ifi->sdl->sdl_index == ifindex)
425 			return(ifi);
426 
427 	return(NULL);
428 }
429 
430 static int
431 make_packet(struct ifinfo *ifinfo)
432 {
433 	char *buf;
434 	struct nd_router_solicit *rs;
435 	size_t packlen = sizeof(struct nd_router_solicit), lladdroptlen = 0;
436 
437 	if ((lladdroptlen = lladdropt_length(ifinfo->sdl)) == 0) {
438 		warnmsg(LOG_INFO, __FUNCTION__,
439 			"link-layer address option has null length"
440 		       " on %s. Treat as not included.", ifinfo->ifname);
441 	}
442 	packlen += lladdroptlen;
443 	ifinfo->rs_datalen = packlen;
444 
445 	/* allocate buffer */
446 	if ((buf = malloc(packlen)) == NULL) {
447 		warnmsg(LOG_ERR, __FUNCTION__,
448 			"memory allocation failed for %s", ifinfo->ifname);
449 		return(-1);
450 	}
451 	ifinfo->rs_data = buf;
452 
453 	/* fill in the message */
454 	rs = (struct nd_router_solicit *)buf;
455 	rs->nd_rs_type = ND_ROUTER_SOLICIT;
456 	rs->nd_rs_code = 0;
457 	rs->nd_rs_cksum = 0;
458 	rs->nd_rs_reserved = 0;
459 	buf += sizeof(*rs);
460 
461 	/* fill in source link-layer address option */
462 	if (lladdroptlen)
463 		lladdropt_fill(ifinfo->sdl, (struct nd_opt_hdr *)buf);
464 
465 	return(0);
466 }
467 
468 static struct timeval *
469 rtsol_check_timer()
470 {
471 	static struct timeval returnval;
472 	struct timeval now, rtsol_timer;
473 	struct ifinfo *ifinfo;
474 	int flags;
475 
476 	gettimeofday(&now, NULL);
477 
478 	rtsol_timer = tm_max;
479 
480 	for (ifinfo = iflist; ifinfo; ifinfo = ifinfo->next) {
481 		if (TIMEVAL_LEQ(ifinfo->expire, now)) {
482 			if (dflag > 1)
483 				warnmsg(LOG_DEBUG, __FUNCTION__,
484 					"timer expiration on %s, "
485 				       "state = %d", ifinfo->ifname,
486 				       ifinfo->state);
487 
488 			switch (ifinfo->state) {
489 			case IFS_DOWN:
490 			case IFS_TENTATIVE:
491 				/* interface_up returns 0 on success */
492 				flags = interface_up(ifinfo->ifname);
493 				if (flags == 0)
494 					ifinfo->state = IFS_DELAY;
495 				else if (flags == IFS_TENTATIVE)
496 					ifinfo->state = IFS_TENTATIVE;
497 				else
498 					ifinfo->state = IFS_DOWN;
499 				break;
500 			case IFS_IDLE:
501 			{
502 				int oldstatus = ifinfo->active;
503 				int probe = 0;
504 
505 				ifinfo->active =
506 					interface_status(ifinfo);
507 
508 				if (oldstatus != ifinfo->active) {
509 					warnmsg(LOG_DEBUG, __FUNCTION__,
510 						"%s status is changed"
511 						" from %d to %d",
512 						ifinfo->ifname,
513 						oldstatus, ifinfo->active);
514 					probe = 1;
515 					ifinfo->state = IFS_DELAY;
516 				}
517 				else if (ifinfo->probeinterval &&
518 					 (ifinfo->probetimer -=
519 					  ifinfo->timer.tv_sec) <= 0) {
520 					/* probe timer expired */
521 					ifinfo->probetimer =
522 						ifinfo->probeinterval;
523 					probe = 1;
524 					ifinfo->state = IFS_PROBE;
525 				}
526 
527 				if (probe && mobile_node)
528 					defrouter_probe(ifinfo->sdl->sdl_index);
529 				break;
530 			}
531 			case IFS_DELAY:
532 				ifinfo->state = IFS_PROBE;
533 				sendpacket(ifinfo);
534 				break;
535 			case IFS_PROBE:
536 				if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
537 					sendpacket(ifinfo);
538 				else {
539 					warnmsg(LOG_INFO, __FUNCTION__,
540 						"No answer "
541 						"after sending %d RSs",
542 						ifinfo->probes);
543 					ifinfo->probes = 0;
544 					ifinfo->state = IFS_IDLE;
545 				}
546 				break;
547 			}
548 			rtsol_timer_update(ifinfo);
549 		}
550 
551 		if (TIMEVAL_LT(ifinfo->expire, rtsol_timer))
552 			rtsol_timer = ifinfo->expire;
553 	}
554 
555 	if (TIMEVAL_EQ(rtsol_timer, tm_max)) {
556 		warnmsg(LOG_DEBUG, __FUNCTION__, "there is no timer");
557 		return(NULL);
558 	}
559 	else if (TIMEVAL_LT(rtsol_timer, now))
560 		/* this may occur when the interval is too small */
561 		returnval.tv_sec = returnval.tv_usec = 0;
562 	else
563 		TIMEVAL_SUB(&rtsol_timer, &now, &returnval);
564 
565 	if (dflag > 1)
566 		warnmsg(LOG_DEBUG, __FUNCTION__, "New timer is %ld:%08ld",
567 			(long)returnval.tv_sec, (long)returnval.tv_usec);
568 
569 	return(&returnval);
570 }
571 
572 void
573 rtsol_timer_update(struct ifinfo *ifinfo)
574 {
575 #define MILLION 1000000
576 #define DADRETRY 10		/* XXX: adhoc */
577 	long interval;
578 	struct timeval now;
579 
580 	bzero(&ifinfo->timer, sizeof(ifinfo->timer));
581 
582 	switch (ifinfo->state) {
583 	case IFS_DOWN:
584 	case IFS_TENTATIVE:
585 		if (++ifinfo->dadcount > DADRETRY) {
586 			ifinfo->dadcount = 0;
587 			ifinfo->timer.tv_sec = PROBE_INTERVAL;
588 		}
589 		else
590 			ifinfo->timer.tv_sec = 1;
591 		break;
592 	case IFS_IDLE:
593 		if (mobile_node) {
594 			/* XXX should be configurable */
595 			ifinfo->timer.tv_sec = 3;
596 		}
597 		else
598 			ifinfo->timer = tm_max;	/* stop timer(valid?) */
599 		break;
600 	case IFS_DELAY:
601 #ifndef HAVE_ARC4RANDOM
602 		interval = random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
603 #else
604 		interval = arc4random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
605 #endif
606 		ifinfo->timer.tv_sec = interval / MILLION;
607 		ifinfo->timer.tv_usec = interval % MILLION;
608 		break;
609 	case IFS_PROBE:
610 		if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
611 			ifinfo->timer.tv_sec = RTR_SOLICITATION_INTERVAL;
612 		else {
613 			/*
614 			 * After sending MAX_RTR_SOLICITATIONS solicitations,
615 			 * we're just waiting for possible replies; there
616 			 * will be no more solicatation.  Thus, we change
617 			 * the timer value to MAX_RTR_SOLICITATION_DELAY based
618 			 * on RFC 2461, Section 6.3.7.
619 			 */
620 			ifinfo->timer.tv_sec = MAX_RTR_SOLICITATION_DELAY;
621 		}
622 		break;
623 	default:
624 		warnmsg(LOG_ERR, __FUNCTION__,
625 			"illegal interface state(%d) on %s",
626 			ifinfo->state, ifinfo->ifname);
627 		return;
628 	}
629 
630 	/* reset the timer */
631 	if (TIMEVAL_EQ(ifinfo->timer, tm_max)) {
632 		ifinfo->expire = tm_max;
633 		warnmsg(LOG_DEBUG, __FUNCTION__,
634 			"stop timer for %s", ifinfo->ifname);
635 	}
636 	else {
637 		gettimeofday(&now, NULL);
638 		TIMEVAL_ADD(&now, &ifinfo->timer, &ifinfo->expire);
639 
640 		if (dflag > 1)
641 			warnmsg(LOG_DEBUG, __FUNCTION__,
642 				"set timer for %s to %d:%d", ifinfo->ifname,
643 			       (int)ifinfo->timer.tv_sec,
644 			       (int)ifinfo->timer.tv_usec);
645 	}
646 
647 #undef MILLION
648 }
649 
650 /* timer related utility functions */
651 #define MILLION 1000000
652 
653 /* result = a + b */
654 static void
655 TIMEVAL_ADD(struct timeval *a, struct timeval *b, struct timeval *result)
656 {
657 	long l;
658 
659 	if ((l = a->tv_usec + b->tv_usec) < MILLION) {
660 		result->tv_usec = l;
661 		result->tv_sec = a->tv_sec + b->tv_sec;
662 	}
663 	else {
664 		result->tv_usec = l - MILLION;
665 		result->tv_sec = a->tv_sec + b->tv_sec + 1;
666 	}
667 }
668 
669 /*
670  * result = a - b
671  * XXX: this function assumes that a >= b.
672  */
673 void
674 TIMEVAL_SUB(struct timeval *a, struct timeval *b, struct timeval *result)
675 {
676 	long l;
677 
678 	if ((l = a->tv_usec - b->tv_usec) >= 0) {
679 		result->tv_usec = l;
680 		result->tv_sec = a->tv_sec - b->tv_sec;
681 	}
682 	else {
683 		result->tv_usec = MILLION + l;
684 		result->tv_sec = a->tv_sec - b->tv_sec - 1;
685 	}
686 }
687 
688 static void
689 rtsold_set_dump_file()
690 {
691 	do_dump = 1;
692 }
693 
694 static void
695 usage(char *progname)
696 {
697 	if (progname && progname[strlen(progname) - 1] != 'd') {
698 		fprintf(stderr, "usage: rtsol [-dD] interfaces...\n");
699 		fprintf(stderr, "usage: rtsol [-dD] -a\n");
700 	} else {
701 		fprintf(stderr, "usage: rtsold [-adDfm1] interfaces...\n");
702 		fprintf(stderr, "usage: rtsold [-dDfm1] -a\n");
703 	}
704 	exit(1);
705 }
706 
707 void
708 #if __STDC__
709 warnmsg(int priority, const char *func, const char *msg, ...)
710 #else
711 warnmsg(priority, func, msg, va_alist)
712 	int priority;
713 	const char *func;
714 	const char *msg;
715 	va_dcl
716 #endif
717 {
718 	va_list ap;
719 	char buf[BUFSIZ];
720 
721 	va_start(ap, msg);
722 	if (fflag) {
723 		if (priority <= log_upto) {
724 			(void)vfprintf(stderr, msg, ap);
725 			(void)fprintf(stderr, "\n");
726 		}
727 	} else {
728 		snprintf(buf, sizeof(buf), "<%s> %s", func, msg);
729 		msg = buf;
730 		vsyslog(priority, msg, ap);
731 	}
732 	va_end(ap);
733 }
734 
735 static char **
736 autoifprobe()
737 {
738 #ifndef HAVE_GETIFADDRS
739 	errx(1, "-a is not available with the configuration");
740 #else
741 	static char ifname[IFNAMSIZ + 1];
742 	static char *argv[2];
743 	struct ifaddrs *ifap, *ifa, *target;
744 
745 	if (getifaddrs(&ifap) != 0)
746 		return NULL;
747 
748 	target = NULL;
749 	/* find an ethernet */
750 	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
751 		if ((ifa->ifa_flags & IFF_UP) == 0)
752 			continue;
753 		if ((ifa->ifa_flags & IFF_POINTOPOINT) != 0)
754 			continue;
755 		if ((ifa->ifa_flags & IFF_LOOPBACK) != 0)
756 			continue;
757 		if ((ifa->ifa_flags & IFF_MULTICAST) == 0)
758 			continue;
759 
760 		if (ifa->ifa_addr->sa_family != AF_INET6)
761 			continue;
762 
763 		if (target && strcmp(target->ifa_name, ifa->ifa_name) == 0)
764 			continue;
765 
766 		if (!target)
767 			target = ifa;
768 		else {
769 			/* if we find multiple candidates, failure. */
770 			if (dflag > 1)
771 				warnx("multiple interfaces found");
772 			target = NULL;
773 			break;
774 		}
775 	}
776 
777 	if (target) {
778 		strncpy(ifname, target->ifa_name, sizeof(ifname) - 1);
779 		ifname[sizeof(ifname) - 1] = '\0';
780 		argv[0] = ifname;
781 		argv[1] = NULL;
782 
783 		if (dflag > 0)
784 			warnx("probing %s", argv[0]);
785 	}
786 	freeifaddrs(ifap);
787 	if (target)
788 		return argv;
789 	else
790 		return (char **)NULL;
791 #endif
792 }
793