xref: /dragonfly/usr.sbin/rtsold/rtsold.c (revision 0ca59c34) 
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  */
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 /* static variables and functions */
86 static int mobile_node = 0;
87 static int do_dump;
88 /*
89  * XXX: the following two values should be configurable
90  */
91 static const char *dumpfilename = "/var/run/rtsold.dump";
92 static const char *pidfilename = "/var/run/rtsold.pid";
93 
94 static int ifconfig(char *ifname);
95 #if 0
96 static int ifreconfig(char *ifname);
97 #endif
98 static int make_packet(struct ifinfo *ifinfo);
99 static struct timeval *rtsol_check_timer(void);
100 static void TIMEVAL_ADD(struct timeval *a, struct timeval *b,
101 			     struct timeval *result);
102 static void TIMEVAL_SUB(struct timeval *a, struct timeval *b,
103 			     struct timeval *result);
104 
105 static void rtsold_set_dump_file(int);
106 static void usage(char *progname);
107 static char **autoifprobe(void);
108 
109 int
110 main(int argc, char *argv[])
111 {
112 	int s, rtsock, maxfd, ch;
113 	int once = 0;
114 	struct timeval *timeout;
115 	struct fd_set fdset;
116 	char *argv0;
117 	const char *opts;
118 
119 	/*
120 	 * Initialization
121 	 */
122 	argv0 = argv[0];
123 
124 	/* get option */
125 	if (argv0 && argv0[strlen(argv0) - 1] != 'd') {
126 		fflag = 1;
127 		once = 1;
128 		opts = "adD";
129 	} else
130 		opts = "adDfm1";
131 
132 	while ((ch = getopt(argc, argv, opts)) != -1) {
133 		switch (ch) {
134 		case 'a':
135 			aflag = 1;
136 			break;
137 		case 'd':
138 			dflag = 1;
139 			break;
140 		case 'D':
141 			dflag = 2;
142 			break;
143 		case 'f':
144 			fflag = 1;
145 			break;
146 		case 'm':
147 			mobile_node = 1;
148 			break;
149 		case '1':
150 			once = 1;
151 			break;
152 		default:
153 			usage(argv0);
154 			/*NOTREACHED*/
155 		}
156 	}
157 	argc -= optind;
158 	argv += optind;
159 
160 	if (aflag) {
161 		int i;
162 
163 		if (argc != 0) {
164 			usage(argv0);
165 			/*NOTREACHED*/
166 		}
167 
168 		argv = autoifprobe();
169 		if (!argv) {
170 			errx(1, "could not autoprobe interface");
171 			/*NOTREACHED*/
172 		}
173 
174 		for (i = 0; argv[i]; i++)
175 			;
176 		argc = i;
177 	}
178 	if (argc == 0) {
179 		usage(argv0);
180 		/*NOTREACHED*/
181 	}
182 
183 	/* set log level */
184 	if (dflag == 0)
185 		log_upto = LOG_NOTICE;
186 	if (!fflag) {
187 		char *ident;
188 		ident = strrchr(argv0, '/');
189 		if (!ident)
190 			ident = argv0;
191 		else
192 			ident++;
193 		openlog(ident, LOG_NDELAY|LOG_PID, LOG_DAEMON);
194 		if (log_upto >= 0)
195 			setlogmask(LOG_UPTO(log_upto));
196 	}
197 
198 #ifndef HAVE_ARC4RANDOM
199 	/* random value initilization */
200 	srandom((u_long)time(NULL));
201 #endif
202 
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 	/* initialization to dump internal status to a file */
211 	if (signal(SIGUSR1, rtsold_set_dump_file) == SIG_ERR) {
212 		errx(1, "failed to set signal for dump status");
213 		/*NOTREACHED*/
214 	}
215 
216 	/*
217 	 * Open a socket for sending RS and receiving RA.
218 	 * This should be done before calling ifinit(), since the function
219 	 * uses the socket.
220 	 */
221 	if ((s = sockopen()) < 0) {
222 		errx(1, "failed to open a socket");
223 		/*NOTREACHED*/
224 	}
225 	maxfd = s;
226 	if ((rtsock = rtsock_open()) < 0) {
227 		errx(1, "failed to open a socket");
228 		/*NOTREACHED*/
229 	}
230 	if (rtsock > maxfd)
231 		maxfd = rtsock;
232 
233 	/* configuration per interface */
234 	if (ifinit()) {
235 		errx(1, "failed to initilizatoin interfaces");
236 		/*NOTREACHED*/
237 	}
238 	while (argc--) {
239 		if (ifconfig(*argv)) {
240 			errx(1, "failed to initialize %s", *argv);
241 			/*NOTREACHED*/
242 		}
243 		argv++;
244 	}
245 
246 	/* setup for probing default routers */
247 	if (probe_init()) {
248 		errx(1, "failed to setup for probing routers");
249 		/*NOTREACHED*/
250 	}
251 
252 	if (!fflag)
253 		daemon(0, 0);		/* act as a daemon */
254 
255 	/* dump the current pid */
256 	if (!once) {
257 		pid_t pid = getpid();
258 		FILE *fp;
259 
260 		if ((fp = fopen(pidfilename, "w")) == NULL)
261 			warnmsg(LOG_ERR, __func__,
262 				"failed to open a log file(%s): %s",
263 				pidfilename, strerror(errno));
264 		else {
265 			fprintf(fp, "%d\n", pid);
266 			fclose(fp);
267 		}
268 	}
269 
270 	FD_ZERO(&fdset);
271 	FD_SET(s, &fdset);
272 	FD_SET(rtsock, &fdset);
273 	while (1) {		/* main loop */
274 		int e;
275 		struct fd_set select_fd = fdset;
276 
277 		if (do_dump) {	/* SIGUSR1 */
278 			do_dump = 0;
279 			rtsold_dump_file(dumpfilename);
280 		}
281 
282 		timeout = rtsol_check_timer();
283 
284 		if (once) {
285 			struct ifinfo *ifi;
286 
287 			/* if we have no timeout, we are done (or failed) */
288 			if (timeout == NULL)
289 				break;
290 
291 			/* if all interfaces have got RA packet, we are done */
292 			for (ifi = iflist; ifi; ifi = ifi->next) {
293 				if (ifi->state != IFS_DOWN && ifi->racnt == 0)
294 					break;
295 			}
296 			if (ifi == NULL)
297 				break;
298 		}
299 		e = select(maxfd + 1, &select_fd, NULL, NULL, timeout);
300 		if (e < 1) {
301 			if (e < 0 && errno != EINTR) {
302 				warnmsg(LOG_ERR, __func__, "select: %s",
303 				       strerror(errno));
304 			}
305 			continue;
306 		}
307 
308 		/* packet reception */
309 		if (FD_ISSET(rtsock, &select_fd))
310 			rtsock_input(rtsock);
311 		if (FD_ISSET(s, &select_fd))
312 			rtsol_input(s);
313 	}
314 	/* NOTREACHED */
315 
316 	return 0;
317 }
318 
319 static int
320 ifconfig(char *ifname)
321 {
322 	struct ifinfo *ifinfo;
323 	struct sockaddr_dl *sdl;
324 	int flags;
325 
326 	if ((sdl = if_nametosdl(ifname)) == NULL) {
327 		warnmsg(LOG_ERR, __func__,
328 		       "failed to get link layer information for %s", ifname);
329 		return(-1);
330 	}
331 	if (find_ifinfo(sdl->sdl_index)) {
332 		warnmsg(LOG_ERR, __func__,
333 			"interface %s was already configured", ifname);
334 		free(sdl);
335 		return(-1);
336 	}
337 
338 	if ((ifinfo = malloc(sizeof(*ifinfo))) == NULL) {
339 		warnmsg(LOG_ERR, __func__, "memory allocation failed");
340 		free(sdl);
341 		return(-1);
342 	}
343 	memset(ifinfo, 0, sizeof(*ifinfo));
344 	ifinfo->sdl = sdl;
345 
346 	strncpy(ifinfo->ifname, ifname, sizeof(ifinfo->ifname));
347 
348 	/* construct a router solicitation message */
349 	if (make_packet(ifinfo))
350 		goto bad;
351 
352 	/*
353 	 * check if the interface is available.
354 	 * also check if SIOCGIFMEDIA ioctl is OK on the interface.
355 	 */
356 	ifinfo->mediareqok = 1;
357 	ifinfo->active = interface_status(ifinfo);
358 	if (!ifinfo->mediareqok) {
359 		/*
360 		 * probe routers periodically even if the link status
361 		 * does not change.
362 		 */
363 		ifinfo->probeinterval = PROBE_INTERVAL;
364 	}
365 
366 	/* activate interface: interface_up returns 0 on success */
367 	flags = interface_up(ifinfo->ifname);
368 	if (flags == 0)
369 		ifinfo->state = IFS_DELAY;
370 	else if (flags == IFS_TENTATIVE)
371 		ifinfo->state = IFS_TENTATIVE;
372 	else
373 		ifinfo->state = IFS_DOWN;
374 
375 	rtsol_timer_update(ifinfo);
376 
377 	/* link into chain */
378 	if (iflist)
379 		ifinfo->next = iflist;
380 	iflist = ifinfo;
381 
382 	return(0);
383 
384   bad:
385 	free(ifinfo->sdl);
386 	free(ifinfo);
387 	return(-1);
388 }
389 
390 #if 0
391 static int
392 ifreconfig(char *ifname)
393 {
394 	struct ifinfo *ifi, *prev;
395 	int rv;
396 
397 	prev = NULL;
398 	for (ifi = iflist; ifi; ifi = ifi->next) {
399 		if (strncmp(ifi->ifname, ifname, sizeof(ifi->ifname)) == 0)
400 			break;
401 		prev = ifi;
402 	}
403 	prev->next = ifi->next;
404 
405 	rv = ifconfig(ifname);
406 
407 	/* reclaim it after ifconfig() in case ifname is pointer inside ifi */
408 	if (ifi->rs_data)
409 		free(ifi->rs_data);
410 	free(ifi->sdl);
411 	free(ifi);
412 
413 	return rv;
414 }
415 #endif
416 
417 struct ifinfo *
418 find_ifinfo(int ifindex)
419 {
420 	struct ifinfo *ifi;
421 
422 	for (ifi = iflist; ifi; ifi = ifi->next)
423 		if (ifi->sdl->sdl_index == ifindex)
424 			return(ifi);
425 
426 	return(NULL);
427 }
428 
429 static int
430 make_packet(struct ifinfo *ifinfo)
431 {
432 	char *buf;
433 	struct nd_router_solicit *rs;
434 	size_t packlen = sizeof(struct nd_router_solicit), lladdroptlen = 0;
435 
436 	if ((lladdroptlen = lladdropt_length(ifinfo->sdl)) == 0) {
437 		warnmsg(LOG_INFO, __func__,
438 			"link-layer address option has null length"
439 		       " on %s. Treat as not included.", ifinfo->ifname);
440 	}
441 	packlen += lladdroptlen;
442 	ifinfo->rs_datalen = packlen;
443 
444 	/* allocate buffer */
445 	if ((buf = malloc(packlen)) == NULL) {
446 		warnmsg(LOG_ERR, __func__,
447 			"memory allocation failed for %s", ifinfo->ifname);
448 		return(-1);
449 	}
450 	ifinfo->rs_data = buf;
451 
452 	/* fill in the message */
453 	rs = (struct nd_router_solicit *)buf;
454 	rs->nd_rs_type = ND_ROUTER_SOLICIT;
455 	rs->nd_rs_code = 0;
456 	rs->nd_rs_cksum = 0;
457 	rs->nd_rs_reserved = 0;
458 	buf += sizeof(*rs);
459 
460 	/* fill in source link-layer address option */
461 	if (lladdroptlen)
462 		lladdropt_fill(ifinfo->sdl, (struct nd_opt_hdr *)buf);
463 
464 	return(0);
465 }
466 
467 static struct timeval *
468 rtsol_check_timer(void)
469 {
470 	static struct timeval returnval;
471 	struct timeval now, rtsol_timer;
472 	struct ifinfo *ifinfo;
473 	int flags;
474 
475 	gettimeofday(&now, NULL);
476 
477 	rtsol_timer = tm_max;
478 
479 	for (ifinfo = iflist; ifinfo; ifinfo = ifinfo->next) {
480 		if (TIMEVAL_LEQ(ifinfo->expire, now)) {
481 			if (dflag > 1)
482 				warnmsg(LOG_DEBUG, __func__,
483 					"timer expiration on %s, "
484 				       "state = %d", ifinfo->ifname,
485 				       ifinfo->state);
486 
487 			switch (ifinfo->state) {
488 			case IFS_DOWN:
489 			case IFS_TENTATIVE:
490 				/* interface_up returns 0 on success */
491 				flags = interface_up(ifinfo->ifname);
492 				if (flags == 0)
493 					ifinfo->state = IFS_DELAY;
494 				else if (flags == IFS_TENTATIVE)
495 					ifinfo->state = IFS_TENTATIVE;
496 				else
497 					ifinfo->state = IFS_DOWN;
498 				break;
499 			case IFS_IDLE:
500 			{
501 				int oldstatus = ifinfo->active;
502 				int probe = 0;
503 
504 				ifinfo->active =
505 					interface_status(ifinfo);
506 
507 				if (oldstatus != ifinfo->active) {
508 					warnmsg(LOG_DEBUG, __func__,
509 						"%s status is changed"
510 						" from %d to %d",
511 						ifinfo->ifname,
512 						oldstatus, ifinfo->active);
513 					probe = 1;
514 					ifinfo->state = IFS_DELAY;
515 				}
516 				else if (ifinfo->probeinterval &&
517 					 (ifinfo->probetimer -=
518 					  ifinfo->timer.tv_sec) <= 0) {
519 					/* probe timer expired */
520 					ifinfo->probetimer =
521 						ifinfo->probeinterval;
522 					probe = 1;
523 					ifinfo->state = IFS_PROBE;
524 				}
525 
526 				if (probe && mobile_node)
527 					defrouter_probe(ifinfo->sdl->sdl_index);
528 				break;
529 			}
530 			case IFS_DELAY:
531 				ifinfo->state = IFS_PROBE;
532 				sendpacket(ifinfo);
533 				break;
534 			case IFS_PROBE:
535 				if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
536 					sendpacket(ifinfo);
537 				else {
538 					warnmsg(LOG_INFO, __func__,
539 						"No answer "
540 						"after sending %d RSs",
541 						ifinfo->probes);
542 					ifinfo->probes = 0;
543 					ifinfo->state = IFS_IDLE;
544 				}
545 				break;
546 			}
547 			rtsol_timer_update(ifinfo);
548 		}
549 
550 		if (TIMEVAL_LT(ifinfo->expire, rtsol_timer))
551 			rtsol_timer = ifinfo->expire;
552 	}
553 
554 	if (TIMEVAL_EQ(rtsol_timer, tm_max)) {
555 		warnmsg(LOG_DEBUG, __func__, "there is no timer");
556 		return(NULL);
557 	}
558 	else if (TIMEVAL_LT(rtsol_timer, now))
559 		/* this may occur when the interval is too small */
560 		returnval.tv_sec = returnval.tv_usec = 0;
561 	else
562 		TIMEVAL_SUB(&rtsol_timer, &now, &returnval);
563 
564 	if (dflag > 1)
565 		warnmsg(LOG_DEBUG, __func__, "New timer is %ld:%08ld",
566 			(long)returnval.tv_sec, (long)returnval.tv_usec);
567 
568 	return(&returnval);
569 }
570 
571 void
572 rtsol_timer_update(struct ifinfo *ifinfo)
573 {
574 #define MILLION 1000000
575 #define DADRETRY 10		/* XXX: adhoc */
576 	long interval;
577 	struct timeval now;
578 
579 	bzero(&ifinfo->timer, sizeof(ifinfo->timer));
580 
581 	switch (ifinfo->state) {
582 	case IFS_DOWN:
583 	case IFS_TENTATIVE:
584 		if (++ifinfo->dadcount > DADRETRY) {
585 			ifinfo->dadcount = 0;
586 			ifinfo->timer.tv_sec = PROBE_INTERVAL;
587 		}
588 		else
589 			ifinfo->timer.tv_sec = 1;
590 		break;
591 	case IFS_IDLE:
592 		if (mobile_node) {
593 			/* XXX should be configurable */
594 			ifinfo->timer.tv_sec = 3;
595 		}
596 		else
597 			ifinfo->timer = tm_max;	/* stop timer(valid?) */
598 		break;
599 	case IFS_DELAY:
600 #ifndef HAVE_ARC4RANDOM
601 		interval = random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
602 #else
603 		interval = arc4random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
604 #endif
605 		ifinfo->timer.tv_sec = interval / MILLION;
606 		ifinfo->timer.tv_usec = interval % MILLION;
607 		break;
608 	case IFS_PROBE:
609 		if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
610 			ifinfo->timer.tv_sec = RTR_SOLICITATION_INTERVAL;
611 		else {
612 			/*
613 			 * After sending MAX_RTR_SOLICITATIONS solicitations,
614 			 * we're just waiting for possible replies; there
615 			 * will be no more solicatation.  Thus, we change
616 			 * the timer value to MAX_RTR_SOLICITATION_DELAY based
617 			 * on RFC 2461, Section 6.3.7.
618 			 */
619 			ifinfo->timer.tv_sec = MAX_RTR_SOLICITATION_DELAY;
620 		}
621 		break;
622 	default:
623 		warnmsg(LOG_ERR, __func__,
624 			"illegal interface state(%d) on %s",
625 			ifinfo->state, ifinfo->ifname);
626 		return;
627 	}
628 
629 	/* reset the timer */
630 	if (TIMEVAL_EQ(ifinfo->timer, tm_max)) {
631 		ifinfo->expire = tm_max;
632 		warnmsg(LOG_DEBUG, __func__,
633 			"stop timer for %s", ifinfo->ifname);
634 	}
635 	else {
636 		gettimeofday(&now, NULL);
637 		TIMEVAL_ADD(&now, &ifinfo->timer, &ifinfo->expire);
638 
639 		if (dflag > 1)
640 			warnmsg(LOG_DEBUG, __func__,
641 				"set timer for %s to %d:%d", ifinfo->ifname,
642 			       (int)ifinfo->timer.tv_sec,
643 			       (int)ifinfo->timer.tv_usec);
644 	}
645 
646 #undef MILLION
647 }
648 
649 /* timer related utility functions */
650 #define MILLION 1000000
651 
652 /* result = a + b */
653 static void
654 TIMEVAL_ADD(struct timeval *a, struct timeval *b, struct timeval *result)
655 {
656 	long l;
657 
658 	if ((l = a->tv_usec + b->tv_usec) < MILLION) {
659 		result->tv_usec = l;
660 		result->tv_sec = a->tv_sec + b->tv_sec;
661 	}
662 	else {
663 		result->tv_usec = l - MILLION;
664 		result->tv_sec = a->tv_sec + b->tv_sec + 1;
665 	}
666 }
667 
668 /*
669  * result = a - b
670  * XXX: this function assumes that a >= b.
671  */
672 void
673 TIMEVAL_SUB(struct timeval *a, struct timeval *b, struct timeval *result)
674 {
675 	long l;
676 
677 	if ((l = a->tv_usec - b->tv_usec) >= 0) {
678 		result->tv_usec = l;
679 		result->tv_sec = a->tv_sec - b->tv_sec;
680 	}
681 	else {
682 		result->tv_usec = MILLION + l;
683 		result->tv_sec = a->tv_sec - b->tv_sec - 1;
684 	}
685 }
686 
687 static void
688 rtsold_set_dump_file(int signo __unused)
689 {
690 	do_dump = 1;
691 }
692 
693 static void
694 usage(char *progname)
695 {
696 	if (progname && progname[strlen(progname) - 1] != 'd') {
697 		fprintf(stderr, "usage: rtsol [-dD] interfaces...\n");
698 		fprintf(stderr, "usage: rtsol [-dD] -a\n");
699 	} else {
700 		fprintf(stderr, "usage: rtsold [-adDfm1] interfaces...\n");
701 		fprintf(stderr, "usage: rtsold [-dDfm1] -a\n");
702 	}
703 	exit(1);
704 }
705 
706 void
707 warnmsg(int priority, const char *func, const char *msg, ...)
708 {
709 	va_list ap;
710 	char buf[BUFSIZ];
711 
712 	va_start(ap, msg);
713 	if (fflag) {
714 		if (priority <= log_upto) {
715 			vfprintf(stderr, msg, ap);
716 			fprintf(stderr, "\n");
717 		}
718 	} else {
719 		snprintf(buf, sizeof(buf), "<%s> %s", func, msg);
720 		msg = buf;
721 		vsyslog(priority, msg, ap);
722 	}
723 	va_end(ap);
724 }
725 
726 static char **
727 autoifprobe(void)
728 {
729 #ifndef HAVE_GETIFADDRS
730 	errx(1, "-a is not available with the configuration");
731 #else
732 	static char ifname[IFNAMSIZ + 1];
733 	static char *argv[2];
734 	struct ifaddrs *ifap, *ifa, *target;
735 
736 	if (getifaddrs(&ifap) != 0)
737 		return NULL;
738 
739 	target = NULL;
740 	/* find an ethernet */
741 	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
742 		if ((ifa->ifa_flags & IFF_UP) == 0)
743 			continue;
744 		if ((ifa->ifa_flags & IFF_POINTOPOINT) != 0)
745 			continue;
746 		if ((ifa->ifa_flags & IFF_LOOPBACK) != 0)
747 			continue;
748 		if ((ifa->ifa_flags & IFF_MULTICAST) == 0)
749 			continue;
750 
751 		if (ifa->ifa_addr->sa_family != AF_INET6)
752 			continue;
753 
754 		if (target && strcmp(target->ifa_name, ifa->ifa_name) == 0)
755 			continue;
756 
757 		if (!target)
758 			target = ifa;
759 		else {
760 			/* if we find multiple candidates, failure. */
761 			if (dflag > 1)
762 				warnx("multiple interfaces found");
763 			target = NULL;
764 			break;
765 		}
766 	}
767 
768 	if (target) {
769 		strncpy(ifname, target->ifa_name, sizeof(ifname) - 1);
770 		ifname[sizeof(ifname) - 1] = '\0';
771 		argv[0] = ifname;
772 		argv[1] = NULL;
773 
774 		if (dflag > 0)
775 			warnx("probing %s", argv[0]);
776 	}
777 	freeifaddrs(ifap);
778 	if (target)
779 		return argv;
780 	else
781 		return NULL;
782 #endif
783 }
784