usr.sbin/rtsold/rtsold.c

   1 /*      $NetBSD: rtsold.c,v 1.34 2008/06/23 04:55:27 dholland Exp $     */
   2 /*      $KAME: rtsold.c,v 1.77 2004/01/03 01:35:13 itojun Exp $ */
   3
   4 /*
   5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the project nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <sys/types.h>
  34 #include <sys/time.h>
  35 #include <sys/socket.h>
  36 #include <sys/param.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 <util.h>
  55 #include <poll.h>
  56
  57 #include "rtsold.h"
  58
  59 #ifdef __bsdi__
  60 #define timeradd(tvp, uvp, vvp)                                         \
  61         do {                                                            \
  62                 (vvp)->tv_sec = (tvp)->tv_sec + (uvp)->tv_sec;          \
  63                 (vvp)->tv_usec = (tvp)->tv_usec + (uvp)->tv_usec;       \
  64                 if ((vvp)->tv_usec >= 1000000) {                        \
  65                         (vvp)->tv_sec++;                                \
  66                         (vvp)->tv_usec -= 1000000;                      \
  67                 }                                                       \
  68         } while (/* CONSTCOND */ 0)
  69 #define timersub(tvp, uvp, vvp)                                         \
  70         do {                                                            \
  71                 (vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec;          \
  72                 (vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec;       \
  73                 if ((vvp)->tv_usec < 0) {                               \
  74                         (vvp)->tv_sec--;                                \
  75                         (vvp)->tv_usec += 1000000;                      \
  76                 }                                                       \
  77         } while (/* CONSTCOND */ 0)
  78 #endif
  79
  80 struct ifinfo *iflist;
  81 struct timeval tm_max = {0x7fffffff, 0x7fffffff};
  82 static int log_upto = 999;
  83 static int fflag = 0;
  84
  85 int aflag = 0;
  86 int dflag = 0;
  87
  88 /* protocol constatns */
  89 #define MAX_RTR_SOLICITATION_DELAY      1 /* second */
  90 #define RTR_SOLICITATION_INTERVAL       4 /* seconds */
  91 #define MAX_RTR_SOLICITATIONS           3 /* times */
  92
  93 /*
  94  * implementation dependent constants in seconds
  95  * XXX: should be configurable
  96  */
  97 #define PROBE_INTERVAL 60
  98
  99 int main __P((int, char **));
 100
 101 /* static variables and functions */
 102 static int mobile_node = 0;
 103 #ifndef SMALL
 104 static int do_dump;
 105 static const char *dumpfilename = "/var/run/rtsold.dump"; /* XXX: should be configurable */
 106 #endif
 107
 108 #if 0
 109 static int ifreconfig __P((char *));
 110 #endif
 111 static int make_packet __P((struct ifinfo *));
 112 static struct timeval *rtsol_check_timer __P((void));
 113
 114 #ifndef SMALL
 115 static void rtsold_set_dump_file __P((int));
 116 #endif
 117 static void usage __P((char *));
 118
 119 int
 120 main(int argc, char **argv)
 121 {
 122         int s, ch, once = 0;
 123         struct timeval *timeout;
 124         char *argv0;
 125         const char *opts;
 126         struct pollfd set[2];
 127 #ifdef USE_RTSOCK
 128         int rtsock;
 129 #endif
 130
 131         /*
 132          * Initialization
 133          */
 134         argv0 = argv[0];
 135
 136         /* get option */
 137         if (argv0 && argv0[strlen(argv0) - 1] != 'd') {
 138                 fflag = 1;
 139                 once = 1;
 140                 opts = "adD";
 141         } else
 142                 opts = "adDfm1";
 143
 144         while ((ch = getopt(argc, argv, opts)) != -1) {
 145                 switch (ch) {
 146                 case 'a':
 147                         aflag = 1;
 148                         break;
 149                 case 'd':
 150                         dflag = 1;
 151                         break;
 152                 case 'D':
 153                         dflag = 2;
 154                         break;
 155                 case 'f':
 156                         fflag = 1;
 157                         break;
 158                 case 'm':
 159                         mobile_node = 1;
 160                         break;
 161                 case '1':
 162                         once = 1;
 163                         break;
 164                 default:
 165                         usage(argv0);
 166                         /*NOTREACHED*/
 167                 }
 168         }
 169         argc -= optind;
 170         argv += optind;
 171
 172         if ((!aflag && argc == 0) || (aflag && argc != 0)) {
 173                 usage(argv0);
 174                 /*NOTREACHED*/
 175         }
 176
 177         /* set log level */
 178         if (dflag == 0)
 179                 log_upto = LOG_NOTICE;
 180         if (!fflag) {
 181                 char *ident;
 182
 183                 ident = strrchr(argv0, '/');
 184                 if (!ident)
 185                         ident = argv0;
 186                 else
 187                         ident++;
 188                 openlog(ident, LOG_NDELAY|LOG_PID, LOG_DAEMON);
 189                 if (log_upto >= 0)
 190                         setlogmask(LOG_UPTO(log_upto));
 191         }
 192
 193         /* warn if accept_rtadv is down */
 194         if (!getinet6sysctl(IPV6CTL_ACCEPT_RTADV))
 195                 warnx("kernel is configured not to accept RAs");
 196         /* warn if forwarding is up */
 197         if (getinet6sysctl(IPV6CTL_FORWARDING))
 198                 warnx("kernel is configured as a router, not a host");
 199
 200 #ifndef SMALL
 201         /* initialization to dump internal status to a file */
 202         signal(SIGUSR1, rtsold_set_dump_file);
 203 #endif
 204
 205         if (!fflag)
 206                 daemon(0, 0);           /* act as a daemon */
 207
 208         /*
 209          * Open a socket for sending RS and receiving RA.
 210          * This should be done before calling ifinit(), since the function
 211          * uses the socket.
 212          */
 213         if ((s = sockopen()) < 0) {
 214                 warnmsg(LOG_ERR, __func__, "failed to open a socket");
 215                 exit(1);
 216                 /*NOTREACHED*/
 217         }
 218         set[0].fd = s;
 219         set[0].events = POLLIN;
 220
 221         set[1].fd = -1;
 222
 223 #ifdef USE_RTSOCK
 224         if ((rtsock = rtsock_open()) < 0) {
 225                 warnmsg(LOG_ERR, __func__, "failed to open a socket");
 226                 exit(1);
 227                 /*NOTREACHED*/
 228         }
 229         set[1].fd = rtsock;
 230         set[1].events = POLLIN;
 231 #endif
 232
 233         /* configuration per interface */
 234         if (ifinit()) {
 235                 warnmsg(LOG_ERR, __func__,
 236                     "failed to initilizatoin interfaces");
 237                 exit(1);
 238                 /*NOTREACHED*/
 239         }
 240         if (aflag)
 241                 argv = autoifprobe();
 242         while (argv && *argv) {
 243                 if (ifconfig(*argv)) {
 244                         warnmsg(LOG_ERR, __func__,
 245                             "failed to initialize %s", *argv);
 246                         exit(1);
 247                         /*NOTREACHED*/
 248                 }
 249                 argv++;
 250         }
 251
 252         /* setup for probing default routers */
 253         if (probe_init()) {
 254                 warnmsg(LOG_ERR, __func__,
 255                     "failed to setup for probing routers");
 256                 exit(1);
 257                 /*NOTREACHED*/
 258         }
 259
 260         /* dump the current pid */
 261         if (!once) {
 262                 if (pidfile(NULL) < 0) {
 263                         warnmsg(LOG_ERR, __func__,
 264                             "failed to open a pid log file: %s",
 265                             strerror(errno));
 266                 }
 267         }
 268
 269         for (;;) {              /* main loop */
 270                 int e;
 271
 272 #ifndef SMALL
 273                 if (do_dump) {  /* SIGUSR1 */
 274                         do_dump = 0;
 275                         rtsold_dump_file(dumpfilename);
 276                 }
 277 #endif
 278
 279                 timeout = rtsol_check_timer();
 280
 281                 if (once) {
 282                         struct ifinfo *ifi;
 283
 284                         /* if we have no timeout, we are done (or failed) */
 285                         if (timeout == NULL)
 286                                 break;
 287
 288                         /* if all interfaces have got RA packet, we are done */
 289                         for (ifi = iflist; ifi; ifi = ifi->next) {
 290                                 if (ifi->state != IFS_DOWN && ifi->racnt == 0)
 291                                         break;
 292                         }
 293                         if (ifi == NULL)
 294                                 break;
 295                 }
 296                 e = poll(set, 2, timeout ? (timeout->tv_sec * 1000 + timeout->tv_usec / 1000) : INFTIM);
 297                 if (e < 1) {
 298                         if (e < 0 && errno != EINTR) {
 299                                 warnmsg(LOG_ERR, __func__, "poll: %s",
 300                                     strerror(errno));
 301                         }
 302                         continue;
 303                 }
 304
 305                 /* packet reception */
 306 #ifdef USE_RTSOCK
 307                 if (set[1].revents & POLLIN)
 308                         rtsock_input(rtsock);
 309 #endif
 310                 if (set[0].revents & POLLIN)
 311                         rtsol_input(s);
 312         }
 313         /* NOTREACHED */
 314
 315         return 0;
 316 }
 317
 318 int
 319 ifconfig(char *ifname)
 320 {
 321         struct ifinfo *ifinfo;
 322         struct sockaddr_dl *sdl;
 323         int flags;
 324
 325         if ((sdl = if_nametosdl(ifname)) == NULL) {
 326                 warnmsg(LOG_ERR, __func__,
 327                     "failed to get link layer information for %s", ifname);
 328                 return(-1);
 329         }
 330         if (find_ifinfo(sdl->sdl_index)) {
 331                 warnmsg(LOG_ERR, __func__,
 332                     "interface %s was already configured", ifname);
 333                 free(sdl);
 334                 return(-1);
 335         }
 336
 337         if ((ifinfo = malloc(sizeof(*ifinfo))) == NULL) {
 338                 warnmsg(LOG_ERR, __func__, "memory allocation failed");
 339                 free(sdl);
 340                 return(-1);
 341         }
 342         memset(ifinfo, 0, sizeof(*ifinfo));
 343         ifinfo->sdl = sdl;
 344
 345         strlcpy(ifinfo->ifname, ifname, sizeof(ifinfo->ifname));
 346
 347         /* construct a router solicitation message */
 348         if (make_packet(ifinfo))
 349                 goto bad;
 350
 351         /* set link ID of this interface. */
 352 #ifdef HAVE_SCOPELIB
 353         if (inet_zoneid(AF_INET6, 2, ifname, &ifinfo->linkid))
 354                 goto bad;
 355 #else
 356         /* XXX: assume interface IDs as link IDs */
 357         ifinfo->linkid = ifinfo->sdl->sdl_index;
 358 #endif
 359
 360         /*
 361          * check if the interface is available.
 362          * also check if SIOCGIFMEDIA ioctl is OK on the interface.
 363          */
 364         ifinfo->mediareqok = 1;
 365         ifinfo->active = interface_status(ifinfo);
 366         if (!ifinfo->mediareqok) {
 367                 /*
 368                  * probe routers periodically even if the link status
 369                  * does not change.
 370                  */
 371                 ifinfo->probeinterval = PROBE_INTERVAL;
 372         }
 373
 374         /* activate interface: interface_up returns 0 on success */
 375         flags = interface_up(ifinfo->ifname);
 376         if (flags == 0)
 377                 ifinfo->state = IFS_DELAY;
 378         else if (flags == IFS_TENTATIVE)
 379                 ifinfo->state = IFS_TENTATIVE;
 380         else
 381                 ifinfo->state = IFS_DOWN;
 382
 383         rtsol_timer_update(ifinfo);
 384
 385         /* link into chain */
 386         if (iflist)
 387                 ifinfo->next = iflist;
 388         iflist = ifinfo;
 389
 390         return(0);
 391
 392 bad:
 393         free(ifinfo->sdl);
 394         free(ifinfo);
 395         return(-1);
 396 }
 397
 398 void
 399 iflist_init(void)
 400 {
 401         struct ifinfo *ifi, *next;
 402
 403         for (ifi = iflist; ifi; ifi = next) {
 404                 next = ifi->next;
 405                 if (ifi->sdl)
 406                         free(ifi->sdl);
 407                 if (ifi->rs_data)
 408                         free(ifi->rs_data);
 409                 free(ifi);
 410                 iflist = NULL;
 411         }
 412 }
 413
 414 #if 0
 415 static int
 416 ifreconfig(char *ifname)
 417 {
 418         struct ifinfo *ifi, *prev;
 419         int rv;
 420
 421         prev = NULL;
 422         for (ifi = iflist; ifi; ifi = ifi->next) {
 423                 if (strncmp(ifi->ifname, ifname, sizeof(ifi->ifname)) == 0)
 424                         break;
 425                 prev = ifi;
 426         }
 427         prev->next = ifi->next;
 428
 429         rv = ifconfig(ifname);
 430
 431         /* reclaim it after ifconfig() in case ifname is pointer inside ifi */
 432         if (ifi->rs_data)
 433                 free(ifi->rs_data);
 434         free(ifi->sdl);
 435         free(ifi);
 436         return rv;
 437 }
 438 #endif
 439
 440 struct ifinfo *
 441 find_ifinfo(int ifindex)
 442 {
 443         struct ifinfo *ifi;
 444
 445         for (ifi = iflist; ifi; ifi = ifi->next)
 446                 if (ifi->sdl->sdl_index == ifindex)
 447                         return(ifi);
 448         return(NULL);
 449 }
 450
 451 static int
 452 make_packet(struct ifinfo *ifinfo)
 453 {
 454         size_t packlen = sizeof(struct nd_router_solicit), lladdroptlen = 0;
 455         struct nd_router_solicit *rs;
 456         u_char *buf;
 457
 458         if ((lladdroptlen = lladdropt_length(ifinfo->sdl)) == 0) {
 459                 warnmsg(LOG_INFO, __func__,
 460                     "link-layer address option has null length"
 461                     " on %s. Treat as not included.", ifinfo->ifname);
 462         }
 463         packlen += lladdroptlen;
 464         ifinfo->rs_datalen = packlen;
 465
 466         /* allocate buffer */
 467         if ((buf = malloc(packlen)) == NULL) {
 468                 warnmsg(LOG_ERR, __func__,
 469                     "memory allocation failed for %s", ifinfo->ifname);
 470                 return(-1);
 471         }
 472         ifinfo->rs_data = buf;
 473
 474         /* fill in the message */
 475         rs = (struct nd_router_solicit *)buf;
 476         rs->nd_rs_type = ND_ROUTER_SOLICIT;
 477         rs->nd_rs_code = 0;
 478         rs->nd_rs_cksum = 0;
 479         rs->nd_rs_reserved = 0;
 480         buf += sizeof(*rs);
 481
 482         /* fill in source link-layer address option */
 483         if (lladdroptlen)
 484                 lladdropt_fill(ifinfo->sdl, (struct nd_opt_hdr *)buf);
 485
 486         return(0);
 487 }
 488
 489 static struct timeval *
 490 rtsol_check_timer(void)
 491 {
 492         static struct timeval returnval;
 493         struct timeval now, rtsol_timer;
 494         struct ifinfo *ifinfo;
 495         int flags;
 496
 497         gettimeofday(&now, NULL);
 498
 499         rtsol_timer = tm_max;
 500
 501         for (ifinfo = iflist; ifinfo; ifinfo = ifinfo->next) {
 502                 if (timercmp(&ifinfo->expire, &now, <=)) {
 503                         if (dflag > 1)
 504                                 warnmsg(LOG_DEBUG, __func__,
 505                                     "timer expiration on %s, "
 506                                     "state = %d", ifinfo->ifname,
 507                                     ifinfo->state);
 508
 509                         switch (ifinfo->state) {
 510                         case IFS_DOWN:
 511                         case IFS_TENTATIVE:
 512                                 /* interface_up returns 0 on success */
 513                                 flags = interface_up(ifinfo->ifname);
 514                                 if (flags == 0)
 515                                         ifinfo->state = IFS_DELAY;
 516                                 else if (flags == IFS_TENTATIVE)
 517                                         ifinfo->state = IFS_TENTATIVE;
 518                                 else
 519                                         ifinfo->state = IFS_DOWN;
 520                                 break;
 521                         case IFS_IDLE:
 522                         {
 523                                 int oldstatus = ifinfo->active;
 524                                 int probe = 0;
 525
 526                                 ifinfo->active = interface_status(ifinfo);
 527
 528                                 if (oldstatus != ifinfo->active) {
 529                                         warnmsg(LOG_DEBUG, __func__,
 530                                             "%s status is changed"
 531                                             " from %d to %d",
 532                                             ifinfo->ifname,
 533                                             oldstatus, ifinfo->active);
 534                                         probe = 1;
 535                                         ifinfo->state = IFS_DELAY;
 536                                 } else if (ifinfo->probeinterval &&
 537                                     (ifinfo->probetimer -=
 538                                     ifinfo->timer.tv_sec) <= 0) {
 539                                         /* probe timer expired */
 540                                         ifinfo->probetimer =
 541                                             ifinfo->probeinterval;
 542                                         probe = 1;
 543                                         ifinfo->state = IFS_PROBE;
 544                                 }
 545
 546                                 if (probe && mobile_node)
 547                                         defrouter_probe(ifinfo);
 548                                 break;
 549                         }
 550                         case IFS_DELAY:
 551                                 ifinfo->state = IFS_PROBE;
 552                                 sendpacket(ifinfo);
 553                                 break;
 554                         case IFS_PROBE:
 555                                 if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
 556                                         sendpacket(ifinfo);
 557                                 else {
 558                                         warnmsg(LOG_INFO, __func__,
 559                                             "No answer after sending %d RSs",
 560                                             ifinfo->probes);
 561                                         ifinfo->probes = 0;
 562                                         ifinfo->state = IFS_IDLE;
 563                                 }
 564                                 break;
 565                         }
 566                         rtsol_timer_update(ifinfo);
 567                 }
 568
 569                 if (timercmp(&ifinfo->expire, &rtsol_timer, <))
 570                         rtsol_timer = ifinfo->expire;
 571         }
 572
 573         if (timercmp(&rtsol_timer, &tm_max, ==)) {
 574                 warnmsg(LOG_DEBUG, __func__, "there is no timer");
 575                 return(NULL);
 576         } else if (timercmp(&rtsol_timer, &now, <))
 577                 /* this may occur when the interval is too small */
 578                 returnval.tv_sec = returnval.tv_usec = 0;
 579         else
 580                 timersub(&rtsol_timer, &now, &returnval);
 581
 582         if (dflag > 1)
 583                 warnmsg(LOG_DEBUG, __func__, "New timer is %ld:%08ld",
 584                     (long)returnval.tv_sec, (long)returnval.tv_usec);
 585
 586         return(&returnval);
 587 }
 588
 589 void
 590 rtsol_timer_update(struct ifinfo *ifinfo)
 591 {
 592 #define MILLION 1000000
 593 #define DADRETRY 10             /* XXX: adhoc */
 594         long interval;
 595         struct timeval now;
 596
 597         bzero(&ifinfo->timer, sizeof(ifinfo->timer));
 598
 599         switch (ifinfo->state) {
 600         case IFS_DOWN:
 601         case IFS_TENTATIVE:
 602                 if (++ifinfo->dadcount > DADRETRY) {
 603                         ifinfo->dadcount = 0;
 604                         ifinfo->timer.tv_sec = PROBE_INTERVAL;
 605                 } else
 606                         ifinfo->timer.tv_sec = 1;
 607                 break;
 608         case IFS_IDLE:
 609                 if (mobile_node) {
 610                         /* XXX should be configurable */
 611                         ifinfo->timer.tv_sec = 3;
 612                 } else
 613                         ifinfo->timer = tm_max; /* stop timer(valid?) */
 614                 break;
 615         case IFS_DELAY:
 616                 interval = arc4random() % (MAX_RTR_SOLICITATION_DELAY * MILLION);
 617                 ifinfo->timer.tv_sec = interval / MILLION;
 618                 ifinfo->timer.tv_usec = interval % MILLION;
 619                 break;
 620         case IFS_PROBE:
 621                 if (ifinfo->probes < MAX_RTR_SOLICITATIONS)
 622                         ifinfo->timer.tv_sec = RTR_SOLICITATION_INTERVAL;
 623                 else {
 624                         /*
 625                          * After sending MAX_RTR_SOLICITATIONS solicitations,
 626                          * we're just waiting for possible replies; there
 627                          * will be no more solicatation.  Thus, we change
 628                          * the timer value to MAX_RTR_SOLICITATION_DELAY based
 629                          * on RFC 2461, Section 6.3.7.
 630                          */
 631                         ifinfo->timer.tv_sec = MAX_RTR_SOLICITATION_DELAY;
 632                 }
 633                 break;
 634         default:
 635                 warnmsg(LOG_ERR, __func__,
 636                     "illegal interface state(%d) on %s",
 637                     ifinfo->state, ifinfo->ifname);
 638                 return;
 639         }
 640
 641         /* reset the timer */
 642         if (timercmp(&ifinfo->timer, &tm_max, ==)) {
 643                 ifinfo->expire = tm_max;
 644                 warnmsg(LOG_DEBUG, __func__,
 645                     "stop timer for %s", ifinfo->ifname);
 646         } else {
 647                 gettimeofday(&now, NULL);
 648                 timeradd(&now, &ifinfo->timer, &ifinfo->expire);
 649
 650                 if (dflag > 1)
 651                         warnmsg(LOG_DEBUG, __func__,
 652                             "set timer for %s to %d:%d", ifinfo->ifname,
 653                             (int)ifinfo->timer.tv_sec,
 654                             (int)ifinfo->timer.tv_usec);
 655         }
 656
 657 #undef MILLION
 658 }
 659
 660 /* timer related utility functions */
 661 #define MILLION 1000000
 662
 663 #ifndef SMALL
 664 static void
 665 rtsold_set_dump_file(int sig)
 666 {
 667         do_dump = 1;
 668 }
 669 #endif
 670
 671 static void
 672 usage(char *progname)
 673 {
 674         if (progname && progname[strlen(progname) - 1] != 'd') {
 675                 fprintf(stderr, "usage: rtsol [-Dd] interface ...\n");
 676                 fprintf(stderr, "usage: rtsol [-Dd] -a\n");
 677         } else {
 678                 fprintf(stderr, "usage: rtsold [-1Ddfm] interface ...\n");
 679                 fprintf(stderr, "usage: rtsold [-1Ddfm] -a\n");
 680         }
 681         exit(1);
 682 }
 683
 684 void
 685 warnmsg(int priority, const char *func, const char *msg, ...)
 686 {
 687         va_list ap;
 688         char buf[BUFSIZ];
 689
 690         va_start(ap, msg);
 691         if (fflag) {
 692                 if (priority <= log_upto) {
 693                         (void)vfprintf(stderr, msg, ap);
 694                         (void)fprintf(stderr, "\n");
 695                 }
 696         } else {
 697                 snprintf(buf, sizeof(buf), "<%s> %s", func, msg);
 698                 msg = buf;
 699                 vsyslog(priority, msg, ap);
 700         }
 701         va_end(ap);
 702 }
 703
 704 /*
 705  * return a list of interfaces which is suitable to sending an RS.
 706  */
 707 char **
 708 autoifprobe(void)
 709 {
 710         static char **argv = NULL;
 711         static int n = 0;
 712         char **a;
 713         int i, found;
 714         struct ifaddrs *ifap, *ifa, *target;
 715
 716         /* initialize */
 717         while (n--)
 718                 free(argv[n]);
 719         if (argv) {
 720                 free(argv);
 721                 argv = NULL;
 722         }
 723         n = 0;
 724
 725         if (getifaddrs(&ifap) != 0)
 726                 return NULL;
 727
 728         target = NULL;
 729         /* find an ethernet */
 730         for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
 731                 if ((ifa->ifa_flags & IFF_UP) == 0)
 732                         continue;
 733                 if ((ifa->ifa_flags & IFF_POINTOPOINT) != 0)
 734                         continue;
 735                 if ((ifa->ifa_flags & IFF_LOOPBACK) != 0)
 736                         continue;
 737                 if ((ifa->ifa_flags & IFF_MULTICAST) == 0)
 738                         continue;
 739
 740                 if (ifa->ifa_addr->sa_family != AF_INET6)
 741                         continue;
 742
 743                 found = 0;
 744                 for (i = 0; i < n; i++) {
 745                         if (strcmp(argv[i], ifa->ifa_name) == 0) {
 746                                 found++;
 747                                 break;
 748                         }
 749                 }
 750                 if (found)
 751                         continue;
 752
 753                 /* if we find multiple candidates, just warn. */
 754                 if (n != 0 && dflag > 1)
 755                         warnx("multiple interfaces found");
 756
 757                 a = (char **)realloc(argv, (n + 1) * sizeof(char **));
 758                 if (a == NULL)
 759                         err(1, "realloc");
 760                 argv = a;
 761                 argv[n] = strdup(ifa->ifa_name);
 762                 if (!argv[n])
 763                         err(1, "strdup");
 764                 n++;
 765         }
 766
 767         if (n) {
 768                 a = (char **)realloc(argv, (n + 1) * sizeof(char **));
 769                 if (a == NULL)
 770                         err(1, "realloc");
 771                 argv = a;
 772                 argv[n] = NULL;
 773
 774                 if (dflag > 0) {
 775                         for (i = 0; i < n; i++)
 776                                 warnx("probing %s", argv[i]);
 777                 }
 778         }
 779         freeifaddrs(ifap);
 780         return argv;
 781 }