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
main(int argc,char * argv[])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
ifconfig(char * ifname)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 *
find_ifinfo(int ifindex)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
make_packet(struct ifinfo * ifinfo)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 *
rtsol_check_timer(void)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
rtsol_timer_update(struct ifinfo * ifinfo)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
TIMEVAL_ADD(struct timeval * a,struct timeval * b,struct timeval * result)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
TIMEVAL_SUB(struct timeval * a,struct timeval * b,struct timeval * result)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
rtsold_set_dump_file(int signo __unused)688 rtsold_set_dump_file(int signo __unused)
689 {
690 do_dump = 1;
691 }
692
693 static void
usage(char * progname)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
warnmsg(int priority,const char * func,const char * msg,...)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 **
autoifprobe(void)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