sbin/routed/rdisc.c

   1 /*
   2  * Copyright (c) 1995
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgment:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * $FreeBSD: src/sbin/routed/rdisc.c,v 1.5.2.1 2000/08/14 17:00:04 sheldonh Exp $
  34  * $DragonFly: src/sbin/routed/rdisc.c,v 1.4 2005/03/16 21:21:34 cpressey Exp $
  35  */
  36
  37 #include "defs.h"
  38 #include <netinet/in_systm.h>
  39 #include <netinet/ip.h>
  40 #include <netinet/ip_icmp.h>
  41
  42 #if !defined(sgi) && !defined(__NetBSD__)
  43 static char sccsid[] __attribute__((unused)) = "@(#)rdisc.c     8.1 (Berkeley) x/y/95";
  44 #elif defined(__NetBSD__)
  45 __RCSID("$NetBSD$");
  46 #endif
  47 #ident "$FreeBSD: src/sbin/routed/rdisc.c,v 1.5.2.1 2000/08/14 17:00:04 sheldonh Exp $"
  48
  49 /* router advertisement ICMP packet */
  50 struct icmp_ad {
  51         u_int8_t    icmp_type;          /* type of message */
  52         u_int8_t    icmp_code;          /* type sub code */
  53         u_int16_t   icmp_cksum;         /* ones complement cksum of struct */
  54         u_int8_t    icmp_ad_num;        /* # of following router addresses */
  55         u_int8_t    icmp_ad_asize;      /* 2--words in each advertisement */
  56         u_int16_t   icmp_ad_life;       /* seconds of validity */
  57         struct icmp_ad_info {
  58             n_long  icmp_ad_addr;
  59             n_long  icmp_ad_pref;
  60         } icmp_ad_info[1];
  61 };
  62
  63 /* router solicitation ICMP packet */
  64 struct icmp_so {
  65         u_int8_t    icmp_type;          /* type of message */
  66         u_int8_t    icmp_code;          /* type sub code */
  67         u_int16_t   icmp_cksum;         /* ones complement cksum of struct */
  68         n_long      icmp_so_rsvd;
  69 };
  70
  71 union ad_u {
  72         struct icmp icmp;
  73         struct icmp_ad ad;
  74         struct icmp_so so;
  75 };
  76
  77
  78 int     rdisc_sock = -1;                /* router-discovery raw socket */
  79 struct interface *rdisc_sock_mcast;     /* current multicast interface */
  80
  81 struct timeval rdisc_timer;
  82 int rdisc_ok;                           /* using solicited route */
  83
  84
  85 #define MAX_ADS 16                      /* at least one per interface */
  86 struct dr {                             /* accumulated advertisements */
  87     struct interface *dr_ifp;
  88     naddr   dr_gate;                    /* gateway */
  89     time_t  dr_ts;                      /* when received */
  90     time_t  dr_life;                    /* lifetime in host byte order */
  91     n_long  dr_recv_pref;               /* received but biased preference */
  92     n_long  dr_pref;                    /* preference adjusted by metric */
  93 } *cur_drp, drs[MAX_ADS];
  94
  95 /* convert between signed, balanced around zero,
  96  * and unsigned zero-based preferences */
  97 #define SIGN_PREF(p) ((p) ^ MIN_PreferenceLevel)
  98 #define UNSIGN_PREF(p) SIGN_PREF(p)
  99 /* adjust unsigned preference by interface metric,
 100  * without driving it to infinity */
 101 #define PREF(p, ifp) ((int)(p) <= (ifp)->int_metric ? ((p) != 0 ? 1 : 0) \
 102                       : (p) - ((ifp)->int_metric))
 103
 104 static void rdisc_sort(void);
 105
 106
 107 /* dump an ICMP Router Discovery Advertisement Message
 108  */
 109 static void
 110 trace_rdisc(const char  *act,
 111             naddr       from,
 112             naddr       to,
 113             struct interface *ifp,
 114             union ad_u  *p,
 115             u_int       len)
 116 {
 117         int i;
 118         n_long *wp, *lim;
 119
 120
 121         if (!TRACEPACKETS || ftrace == 0)
 122                 return;
 123
 124         lastlog();
 125
 126         if (p->icmp.icmp_type == ICMP_ROUTERADVERT) {
 127                 fprintf(ftrace, "%s Router Ad"
 128                         " from %s to %s via %s life=%d\n",
 129                         act, naddr_ntoa(from), naddr_ntoa(to),
 130                         ifp ? ifp->int_name : "?",
 131                         ntohs(p->ad.icmp_ad_life));
 132                 if (!TRACECONTENTS)
 133                         return;
 134
 135                 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr;
 136                 lim = &wp[(len - sizeof(p->ad)) / sizeof(*wp)];
 137                 for (i = 0; i < p->ad.icmp_ad_num && wp <= lim; i++) {
 138                         fprintf(ftrace, "\t%s preference=%d",
 139                                 naddr_ntoa(wp[0]), (int)ntohl(wp[1]));
 140                         wp += p->ad.icmp_ad_asize;
 141                 }
 142                 fputc('\n',ftrace);
 143
 144         } else {
 145                 trace_act("%s Router Solic. from %s to %s via %s value=%#x",
 146                           act, naddr_ntoa(from), naddr_ntoa(to),
 147                           ifp ? ifp->int_name : "?",
 148                           (int)ntohl(p->so.icmp_so_rsvd));
 149         }
 150 }
 151
 152 /* prepare Router Discovery socket.
 153  */
 154 static void
 155 get_rdisc_sock(void)
 156 {
 157         if (rdisc_sock < 0) {
 158                 rdisc_sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
 159                 if (rdisc_sock < 0)
 160                         BADERR(1,"rdisc_sock = socket()");
 161                 fix_sock(rdisc_sock,"rdisc_sock");
 162                 fix_select();
 163         }
 164 }
 165
 166
 167 /* Pick multicast group for router-discovery socket
 168  */
 169 void
 170 set_rdisc_mg(struct interface *ifp,
 171              int on)                    /* 0=turn it off */
 172 {
 173         struct ip_mreq m;
 174
 175         if (rdisc_sock < 0) {
 176                 /* Create the raw socket so that we can hear at least
 177                  * broadcast router discovery packets.
 178                  */
 179                 if ((ifp->int_state & IS_NO_RDISC) == IS_NO_RDISC
 180                     || !on)
 181                         return;
 182                 get_rdisc_sock();
 183         }
 184
 185         if (!(ifp->int_if_flags & IFF_MULTICAST)) {
 186                 ifp->int_state &= ~(IS_ALL_HOSTS | IS_ALL_ROUTERS);
 187                 return;
 188         }
 189
 190 #ifdef MCAST_PPP_BUG
 191         if (ifp->int_if_flags & IFF_POINTOPOINT)
 192                 return;
 193 #endif
 194         memset(&m, 0, sizeof(m));
 195         m.imr_interface.s_addr = ((ifp->int_if_flags & IFF_POINTOPOINT)
 196                                   ? ifp->int_dstaddr
 197                                   : ifp->int_addr);
 198         if (supplier
 199             || (ifp->int_state & IS_NO_ADV_IN)
 200             || !on) {
 201                 /* stop listening to advertisements
 202                  */
 203                 if (ifp->int_state & IS_ALL_HOSTS) {
 204                         m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);
 205                         if (setsockopt(rdisc_sock, IPPROTO_IP,
 206                                        IP_DROP_MEMBERSHIP,
 207                                        &m, sizeof(m)) < 0)
 208                                 LOGERR("IP_DROP_MEMBERSHIP ALLHOSTS");
 209                         ifp->int_state &= ~IS_ALL_HOSTS;
 210                 }
 211
 212         } else if (!(ifp->int_state & IS_ALL_HOSTS)) {
 213                 /* start listening to advertisements
 214                  */
 215                 m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);
 216                 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
 217                                &m, sizeof(m)) < 0) {
 218                         LOGERR("IP_ADD_MEMBERSHIP ALLHOSTS");
 219                 } else {
 220                         ifp->int_state |= IS_ALL_HOSTS;
 221                 }
 222         }
 223
 224         if (!supplier
 225             || (ifp->int_state & IS_NO_ADV_OUT)
 226             || !on) {
 227                 /* stop listening to solicitations
 228                  */
 229                 if (ifp->int_state & IS_ALL_ROUTERS) {
 230                         m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP);
 231                         if (setsockopt(rdisc_sock, IPPROTO_IP,
 232                                        IP_DROP_MEMBERSHIP,
 233                                        &m, sizeof(m)) < 0)
 234                                 LOGERR("IP_DROP_MEMBERSHIP ALLROUTERS");
 235                         ifp->int_state &= ~IS_ALL_ROUTERS;
 236                 }
 237
 238         } else if (!(ifp->int_state & IS_ALL_ROUTERS)) {
 239                 /* start hearing solicitations
 240                  */
 241                 m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP);
 242                 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
 243                                &m, sizeof(m)) < 0) {
 244                         LOGERR("IP_ADD_MEMBERSHIP ALLROUTERS");
 245                 } else {
 246                         ifp->int_state |= IS_ALL_ROUTERS;
 247                 }
 248         }
 249 }
 250
 251
 252 /* start supplying routes
 253  */
 254 void
 255 set_supplier(void)
 256 {
 257         struct interface *ifp;
 258         struct dr *drp;
 259
 260         if (supplier_set)
 261                 return;
 262
 263         trace_act("start supplying routes");
 264
 265         /* Forget discovered routes.
 266          */
 267         for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
 268                 drp->dr_recv_pref = 0;
 269                 drp->dr_life = 0;
 270         }
 271         rdisc_age(0);
 272
 273         supplier_set = 1;
 274         supplier = 1;
 275
 276         /* Do not start advertising until we have heard some RIP routes */
 277         LIM_SEC(rdisc_timer, now.tv_sec+MIN_WAITTIME);
 278
 279         /* Switch router discovery multicast groups from soliciting
 280          * to advertising.
 281          */
 282         for (ifp = ifnet; ifp; ifp = ifp->int_next) {
 283                 if (ifp->int_state & IS_BROKE)
 284                         continue;
 285                 ifp->int_rdisc_cnt = 0;
 286                 ifp->int_rdisc_timer.tv_usec = rdisc_timer.tv_usec;
 287                 ifp->int_rdisc_timer.tv_sec = now.tv_sec+MIN_WAITTIME;
 288                 set_rdisc_mg(ifp, 1);
 289         }
 290
 291         /* get rid of any redirects */
 292         del_redirects(0,0);
 293 }
 294
 295
 296 /* age discovered routes and find the best one
 297  */
 298 void
 299 rdisc_age(naddr bad_gate)
 300 {
 301         time_t sec;
 302         struct dr *drp;
 303
 304
 305         /* If only advertising, then do only that. */
 306         if (supplier) {
 307                 /* If switching from client to server, get rid of old
 308                  * default routes.
 309                  */
 310                 if (cur_drp != 0)
 311                         rdisc_sort();
 312                 rdisc_adv();
 313                 return;
 314         }
 315
 316         /* If we are being told about a bad router,
 317          * then age the discovered default route, and if there is
 318          * no alternative, solicit a replacement.
 319          */
 320         if (bad_gate != 0) {
 321                 /* Look for the bad discovered default route.
 322                  * Age it and note its interface.
 323                  */
 324                 for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
 325                         if (drp->dr_ts == 0)
 326                                 continue;
 327
 328                         /* When we find the bad router, then age the route
 329                          * to at most SUPPLY_INTERVAL.
 330                          * This is contrary to RFC 1256, but defends against
 331                          * black holes.
 332                          */
 333                         if (drp->dr_gate == bad_gate) {
 334                                 sec = (now.tv_sec - drp->dr_life
 335                                        + SUPPLY_INTERVAL);
 336                                 if (drp->dr_ts > sec) {
 337                                         trace_act("age 0.0.0.0 --> %s via %s",
 338                                                   naddr_ntoa(drp->dr_gate),
 339                                                   drp->dr_ifp->int_name);
 340                                         drp->dr_ts = sec;
 341                                 }
 342                                 break;
 343                         }
 344                 }
 345         }
 346
 347         rdisc_sol();
 348         rdisc_sort();
 349
 350         /* Delete old redirected routes to keep the kernel table small,
 351          * and to prevent black holes.  Check that the kernel table
 352          * matches the daemon table (i.e. has the default route).
 353          * But only if RIP is not running and we are not dealing with
 354          * a bad gateway, since otherwise age() will be called.
 355          */
 356         if (rip_sock < 0 && bad_gate == 0)
 357                 age(0);
 358 }
 359
 360
 361 /* Zap all routes discovered via an interface that has gone bad
 362  *      This should only be called when !(ifp->int_state & IS_ALIAS)
 363  */
 364 void
 365 if_bad_rdisc(struct interface *ifp)
 366 {
 367         struct dr *drp;
 368
 369         for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
 370                 if (drp->dr_ifp != ifp)
 371                         continue;
 372                 drp->dr_recv_pref = 0;
 373                 drp->dr_ts = 0;
 374                 drp->dr_life = 0;
 375         }
 376
 377         /* make a note to re-solicit, turn RIP on or off, etc. */
 378         rdisc_timer.tv_sec = 0;
 379 }
 380
 381
 382 /* mark an interface ok for router discovering.
 383  */
 384 void
 385 if_ok_rdisc(struct interface *ifp)
 386 {
 387         set_rdisc_mg(ifp, 1);
 388
 389         ifp->int_rdisc_cnt = 0;
 390         ifp->int_rdisc_timer.tv_sec = now.tv_sec + (supplier
 391                                                     ? MIN_WAITTIME
 392                                                     : MAX_SOLICITATION_DELAY);
 393         if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >))
 394                 rdisc_timer = ifp->int_rdisc_timer;
 395 }
 396
 397
 398 /* get rid of a dead discovered router
 399  */
 400 static void
 401 del_rdisc(struct dr *drp)
 402 {
 403         struct interface *ifp;
 404         naddr gate;
 405         int i;
 406
 407
 408         del_redirects(gate = drp->dr_gate, 0);
 409         drp->dr_ts = 0;
 410         drp->dr_life = 0;
 411
 412
 413         /* Count the other discovered routes on the interface.
 414          */
 415         i = 0;
 416         ifp = drp->dr_ifp;
 417         for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
 418                 if (drp->dr_ts != 0
 419                     && drp->dr_ifp == ifp)
 420                         i++;
 421         }
 422
 423         /* If that was the last good discovered router on the interface,
 424          * then solicit a new one.
 425          * This is contrary to RFC 1256, but defends against black holes.
 426          */
 427         if (i != 0) {
 428                 trace_act("discovered router %s via %s"
 429                           " is bad--have %d remaining",
 430                           naddr_ntoa(gate), ifp->int_name, i);
 431         } else if (ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) {
 432                 trace_act("last discovered router %s via %s"
 433                           " is bad--re-solicit",
 434                           naddr_ntoa(gate), ifp->int_name);
 435                 ifp->int_rdisc_cnt = 0;
 436                 ifp->int_rdisc_timer.tv_sec = 0;
 437                 rdisc_sol();
 438         } else {
 439                 trace_act("last discovered router %s via %s"
 440                           " is bad--wait to solicit",
 441                           naddr_ntoa(gate), ifp->int_name);
 442         }
 443 }
 444
 445
 446 /* Find the best discovered route,
 447  * and discard stale routers.
 448  */
 449 static void
 450 rdisc_sort(void)
 451 {
 452         struct dr *drp, *new_drp;
 453         struct rt_entry *rt;
 454         struct rt_spare new;
 455         struct interface *ifp;
 456         u_int new_st = 0;
 457         n_long new_pref = 0;
 458
 459
 460         /* Find the best discovered route.
 461          */
 462         new_drp = 0;
 463         for (drp = drs; drp < &drs[MAX_ADS]; drp++) {
 464                 if (drp->dr_ts == 0)
 465                         continue;
 466                 ifp = drp->dr_ifp;
 467
 468                 /* Get rid of expired discovered routers.
 469                  */
 470                 if (drp->dr_ts + drp->dr_life <= now.tv_sec) {
 471                         del_rdisc(drp);
 472                         continue;
 473                 }
 474
 475                 LIM_SEC(rdisc_timer, drp->dr_ts+drp->dr_life+1);
 476
 477                 /* Update preference with possibly changed interface
 478                  * metric.
 479                  */
 480                 drp->dr_pref = PREF(drp->dr_recv_pref, ifp);
 481
 482                 /* Prefer the current route to prevent thrashing.
 483                  * Prefer shorter lifetimes to speed the detection of
 484                  * bad routers.
 485                  * Avoid sick interfaces.
 486                  */
 487                 if (new_drp == 0
 488                     || (!((new_st ^ drp->dr_ifp->int_state) & IS_SICK)
 489                         && (new_pref < drp->dr_pref
 490                             || (new_pref == drp->dr_pref
 491                                 && (drp == cur_drp
 492                                     || (new_drp != cur_drp
 493                                         && new_drp->dr_life > drp->dr_life)))))
 494                     || ((new_st & IS_SICK)
 495                         && !(drp->dr_ifp->int_state & IS_SICK))) {
 496                             new_drp = drp;
 497                             new_st = drp->dr_ifp->int_state;
 498                             new_pref = drp->dr_pref;
 499                 }
 500         }
 501
 502         /* switch to a better default route
 503          */
 504         if (new_drp != cur_drp) {
 505                 rt = rtget(RIP_DEFAULT, 0);
 506
 507                 /* Stop using discovered routes if they are all bad
 508                  */
 509                 if (new_drp == 0) {
 510                         trace_act("turn off Router Discovery client");
 511                         rdisc_ok = 0;
 512
 513                         if (rt != 0
 514                             && (rt->rt_state & RS_RDISC)) {
 515                                 new = rt->rt_spares[0];
 516                                 new.rts_metric = HOPCNT_INFINITY;
 517                                 new.rts_time = now.tv_sec - GARBAGE_TIME;
 518                                 rtchange(rt, rt->rt_state & ~RS_RDISC,
 519                                          &new, 0);
 520                                 rtswitch(rt, 0);
 521                         }
 522
 523                 } else {
 524                         if (cur_drp == 0) {
 525                                 trace_act("turn on Router Discovery client"
 526                                           " using %s via %s",
 527                                           naddr_ntoa(new_drp->dr_gate),
 528                                           new_drp->dr_ifp->int_name);
 529                                 rdisc_ok = 1;
 530
 531                         } else {
 532                                 trace_act("switch Router Discovery from"
 533                                           " %s via %s to %s via %s",
 534                                           naddr_ntoa(cur_drp->dr_gate),
 535                                           cur_drp->dr_ifp->int_name,
 536                                           naddr_ntoa(new_drp->dr_gate),
 537                                           new_drp->dr_ifp->int_name);
 538                         }
 539
 540                         memset(&new, 0, sizeof(new));
 541                         new.rts_ifp = new_drp->dr_ifp;
 542                         new.rts_gate = new_drp->dr_gate;
 543                         new.rts_router = new_drp->dr_gate;
 544                         new.rts_metric = HOPCNT_INFINITY-1;
 545                         new.rts_time = now.tv_sec;
 546                         if (rt != 0) {
 547                                 rtchange(rt, rt->rt_state | RS_RDISC, &new, 0);
 548                         } else {
 549                                 rtadd(RIP_DEFAULT, 0, RS_RDISC, &new);
 550                         }
 551                 }
 552
 553                 cur_drp = new_drp;
 554         }
 555
 556         /* turn RIP on or off */
 557         if (!rdisc_ok || rip_interfaces > 1) {
 558                 rip_on(0);
 559         } else {
 560                 rip_off();
 561         }
 562 }
 563
 564
 565 /* handle a single address in an advertisement
 566  */
 567 static void
 568 parse_ad(naddr from,
 569          naddr gate,
 570          n_long pref,                   /* signed and in network order */
 571          u_short life,                  /* in host byte order */
 572          struct interface *ifp)
 573 {
 574         static struct msg_limit bad_gate;
 575         struct dr *drp, *new_drp;
 576
 577
 578         if (gate == RIP_DEFAULT
 579             || !check_dst(gate)) {
 580                 msglim(&bad_gate, from,"router %s advertising bad gateway %s",
 581                        naddr_ntoa(from),
 582                        naddr_ntoa(gate));
 583                 return;
 584         }
 585
 586         /* ignore pointers to ourself and routes via unreachable networks
 587          */
 588         if (ifwithaddr(gate, 1, 0) != 0) {
 589                 trace_pkt("    discard Router Discovery Ad pointing at us");
 590                 return;
 591         }
 592         if (!on_net(gate, ifp->int_net, ifp->int_mask)) {
 593                 trace_pkt("    discard Router Discovery Ad"
 594                           " toward unreachable net");
 595                 return;
 596         }
 597
 598         /* Convert preference to an unsigned value
 599          * and later bias it by the metric of the interface.
 600          */
 601         pref = UNSIGN_PREF(ntohl(pref));
 602
 603         if (pref == 0 || life < MinMaxAdvertiseInterval) {
 604                 pref = 0;
 605                 life = 0;
 606         }
 607
 608         for (new_drp = 0, drp = drs; drp < &drs[MAX_ADS]; drp++) {
 609                 /* accept new info for a familiar entry
 610                  */
 611                 if (drp->dr_gate == gate) {
 612                         new_drp = drp;
 613                         break;
 614                 }
 615
 616                 if (life == 0)
 617                         continue;       /* do not worry about dead ads */
 618
 619                 if (drp->dr_ts == 0) {
 620                         new_drp = drp;  /* use unused entry */
 621
 622                 } else if (new_drp == 0) {
 623                         /* look for an entry worse than the new one to
 624                          * reuse.
 625                          */
 626                         if ((!(ifp->int_state & IS_SICK)
 627                              && (drp->dr_ifp->int_state & IS_SICK))
 628                             || (pref > drp->dr_pref
 629                                 && !((ifp->int_state ^ drp->dr_ifp->int_state)
 630                                      & IS_SICK)))
 631                                 new_drp = drp;
 632
 633                 } else if (new_drp->dr_ts != 0) {
 634                         /* look for the least valuable entry to reuse
 635                          */
 636                         if ((!(new_drp->dr_ifp->int_state & IS_SICK)
 637                              && (drp->dr_ifp->int_state & IS_SICK))
 638                             || (new_drp->dr_pref > drp->dr_pref
 639                                 && !((new_drp->dr_ifp->int_state
 640                                       ^ drp->dr_ifp->int_state)
 641                                      & IS_SICK)))
 642                                 new_drp = drp;
 643                 }
 644         }
 645
 646         /* forget it if all of the current entries are better */
 647         if (new_drp == 0)
 648                 return;
 649
 650         new_drp->dr_ifp = ifp;
 651         new_drp->dr_gate = gate;
 652         new_drp->dr_ts = now.tv_sec;
 653         new_drp->dr_life = life;
 654         new_drp->dr_recv_pref = pref;
 655         /* bias functional preference by metric of the interface */
 656         new_drp->dr_pref = PREF(pref,ifp);
 657
 658         /* after hearing a good advertisement, stop asking
 659          */
 660         if (!(ifp->int_state & IS_SICK))
 661                 ifp->int_rdisc_cnt = MAX_SOLICITATIONS;
 662 }
 663
 664
 665 /* Compute the IP checksum
 666  *      This assumes the packet is less than 32K long.
 667  */
 668 static u_short
 669 in_cksum(u_short *p,
 670          u_int len)
 671 {
 672         u_int sum = 0;
 673         int nwords = len >> 1;
 674
 675         while (nwords-- != 0)
 676                 sum += *p++;
 677
 678         if (len & 1)
 679                 sum += *(u_char *)p;
 680
 681         /* end-around-carry */
 682         sum = (sum >> 16) + (sum & 0xffff);
 683         sum += (sum >> 16);
 684         return (~sum);
 685 }
 686
 687
 688 /* Send a router discovery advertisement or solicitation ICMP packet.
 689  */
 690 static void
 691 send_rdisc(union ad_u *p,
 692            int p_size,
 693            struct interface *ifp,
 694            naddr dst,                   /* 0 or unicast destination */
 695            int  type)                   /* 0=unicast, 1=bcast, 2=mcast */
 696 {
 697         struct sockaddr_in in;
 698         int flags;
 699         const char *msg;
 700         naddr tgt_mcast;
 701
 702
 703         memset(&in, 0, sizeof(in));
 704         in.sin_addr.s_addr = dst;
 705         in.sin_family = AF_INET;
 706 #ifdef _HAVE_SIN_LEN
 707         in.sin_len = sizeof(in);
 708 #endif
 709         flags = MSG_DONTROUTE;
 710
 711         switch (type) {
 712         case 0:                         /* unicast */
 713         default:
 714                 msg = "Send";
 715                 break;
 716
 717         case 1:                         /* broadcast */
 718                 if (ifp->int_if_flags & IFF_POINTOPOINT) {
 719                         msg = "Send pt-to-pt";
 720                         in.sin_addr.s_addr = ifp->int_dstaddr;
 721                 } else {
 722                         msg = "Send broadcast";
 723                         in.sin_addr.s_addr = ifp->int_brdaddr;
 724                 }
 725                 break;
 726
 727         case 2:                         /* multicast */
 728                 msg = "Send multicast";
 729                 if (ifp->int_state & IS_DUP) {
 730                         trace_act("abort multicast output via %s"
 731                                   " with duplicate address",
 732                                   ifp->int_name);
 733                         return;
 734                 }
 735                 if (rdisc_sock_mcast != ifp) {
 736                         /* select the right interface. */
 737 #ifdef MCAST_PPP_BUG
 738                         /* Do not specify the primary interface explicitly
 739                          * if we have the multicast point-to-point kernel
 740                          * bug, since the kernel will do the wrong thing
 741                          * if the local address of a point-to-point link
 742                          * is the same as the address of an ordinary
 743                          * interface.
 744                          */
 745                         if (ifp->int_addr == myaddr) {
 746                                 tgt_mcast = 0;
 747                         } else
 748 #endif
 749                         tgt_mcast = ifp->int_addr;
 750                         if (0 > setsockopt(rdisc_sock,
 751                                            IPPROTO_IP, IP_MULTICAST_IF,
 752                                            &tgt_mcast, sizeof(tgt_mcast))) {
 753                                 LOGERR("setsockopt(rdisc_sock,"
 754                                        "IP_MULTICAST_IF)");
 755                                 rdisc_sock_mcast = 0;
 756                                 return;
 757                         }
 758                         rdisc_sock_mcast = ifp;
 759                 }
 760                 flags = 0;
 761                 break;
 762         }
 763
 764         if (rdisc_sock < 0)
 765                 get_rdisc_sock();
 766
 767         trace_rdisc(msg, ifp->int_addr, in.sin_addr.s_addr, ifp,
 768                     p, p_size);
 769
 770         if (0 > sendto(rdisc_sock, p, p_size, flags,
 771                        (struct sockaddr *)&in, sizeof(in))) {
 772                 if (ifp == 0 || !(ifp->int_state & IS_BROKE))
 773                         msglog("sendto(%s%s%s): %s",
 774                                ifp != 0 ? ifp->int_name : "",
 775                                ifp != 0 ? ", " : "",
 776                                inet_ntoa(in.sin_addr),
 777                                strerror(errno));
 778                 if (ifp != 0)
 779                         if_sick(ifp);
 780         }
 781 }
 782
 783
 784 /* Send an advertisement
 785  */
 786 static void
 787 send_adv(struct interface *ifp,
 788          naddr  dst,                    /* 0 or unicast destination */
 789          int    type)                   /* 0=unicast, 1=bcast, 2=mcast */
 790 {
 791         union ad_u u;
 792         n_long pref;
 793
 794
 795         memset(&u, 0, sizeof(u.ad));
 796
 797         u.ad.icmp_type = ICMP_ROUTERADVERT;
 798         u.ad.icmp_ad_num = 1;
 799         u.ad.icmp_ad_asize = sizeof(u.ad.icmp_ad_info[0])/4;
 800
 801         u.ad.icmp_ad_life = stopint ? 0 : htons(ifp->int_rdisc_int*3);
 802
 803         /* Convert the configured preference to an unsigned value,
 804          * bias it by the interface metric, and then send it as a
 805          * signed, network byte order value.
 806          */
 807         pref = UNSIGN_PREF(ifp->int_rdisc_pref);
 808         u.ad.icmp_ad_info[0].icmp_ad_pref = htonl(SIGN_PREF(PREF(pref, ifp)));
 809
 810         u.ad.icmp_ad_info[0].icmp_ad_addr = ifp->int_addr;
 811
 812         u.ad.icmp_cksum = in_cksum((u_short*)&u.ad, sizeof(u.ad));
 813
 814         send_rdisc(&u, sizeof(u.ad), ifp, dst, type);
 815 }
 816
 817
 818 /* Advertise for Router Discovery
 819  */
 820 void
 821 rdisc_adv(void)
 822 {
 823         struct interface *ifp;
 824
 825         if (!supplier)
 826                 return;
 827
 828         rdisc_timer.tv_sec = now.tv_sec + NEVER;
 829
 830         for (ifp = ifnet; ifp; ifp = ifp->int_next) {
 831                 if (0 != (ifp->int_state & (IS_NO_ADV_OUT | IS_BROKE)))
 832                         continue;
 833
 834                 if (!timercmp(&ifp->int_rdisc_timer, &now, >)
 835                     || stopint) {
 836                         send_adv(ifp, htonl(INADDR_ALLHOSTS_GROUP),
 837                                  (ifp->int_state&IS_BCAST_RDISC) ? 1 : 2);
 838                         ifp->int_rdisc_cnt++;
 839
 840                         intvl_random(&ifp->int_rdisc_timer,
 841                                      (ifp->int_rdisc_int*3)/4,
 842                                      ifp->int_rdisc_int);
 843                         if (ifp->int_rdisc_cnt < MAX_INITIAL_ADVERTS
 844                             && (ifp->int_rdisc_timer.tv_sec
 845                                 > MAX_INITIAL_ADVERT_INTERVAL)) {
 846                                 ifp->int_rdisc_timer.tv_sec
 847                                 = MAX_INITIAL_ADVERT_INTERVAL;
 848                         }
 849                         timevaladd(&ifp->int_rdisc_timer, &now);
 850                 }
 851
 852                 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >))
 853                         rdisc_timer = ifp->int_rdisc_timer;
 854         }
 855 }
 856
 857
 858 /* Solicit for Router Discovery
 859  */
 860 void
 861 rdisc_sol(void)
 862 {
 863         struct interface *ifp;
 864         union ad_u u;
 865
 866
 867         if (supplier)
 868                 return;
 869
 870         rdisc_timer.tv_sec = now.tv_sec + NEVER;
 871
 872         for (ifp = ifnet; ifp; ifp = ifp->int_next) {
 873                 if (0 != (ifp->int_state & (IS_NO_SOL_OUT | IS_BROKE))
 874                     || ifp->int_rdisc_cnt >= MAX_SOLICITATIONS)
 875                         continue;
 876
 877                 if (!timercmp(&ifp->int_rdisc_timer, &now, >)) {
 878                         memset(&u, 0, sizeof(u.so));
 879                         u.so.icmp_type = ICMP_ROUTERSOLICIT;
 880                         u.so.icmp_cksum = in_cksum((u_short*)&u.so,
 881                                                    sizeof(u.so));
 882                         send_rdisc(&u, sizeof(u.so), ifp,
 883                                    htonl(INADDR_ALLROUTERS_GROUP),
 884                                    ((ifp->int_state&IS_BCAST_RDISC) ? 1 : 2));
 885
 886                         if (++ifp->int_rdisc_cnt >= MAX_SOLICITATIONS)
 887                                 continue;
 888
 889                         ifp->int_rdisc_timer.tv_sec = SOLICITATION_INTERVAL;
 890                         ifp->int_rdisc_timer.tv_usec = 0;
 891                         timevaladd(&ifp->int_rdisc_timer, &now);
 892                 }
 893
 894                 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >))
 895                         rdisc_timer = ifp->int_rdisc_timer;
 896         }
 897 }
 898
 899
 900 /* check the IP header of a possible Router Discovery ICMP packet */
 901 static struct interface *               /* 0 if bad */
 902 ck_icmp(const char *act,
 903         naddr   from,
 904         struct interface *ifp,
 905         naddr   to,
 906         union ad_u *p,
 907         u_int   len)
 908 {
 909         const char *type;
 910
 911
 912         if (p->icmp.icmp_type == ICMP_ROUTERADVERT) {
 913                 type = "advertisement";
 914         } else if (p->icmp.icmp_type == ICMP_ROUTERSOLICIT) {
 915                 type = "solicitation";
 916         } else {
 917                 return 0;
 918         }
 919
 920         if (p->icmp.icmp_code != 0) {
 921                 trace_pkt("unrecognized ICMP Router %s code=%d from %s to %s",
 922                           type, p->icmp.icmp_code,
 923                           naddr_ntoa(from), naddr_ntoa(to));
 924                 return 0;
 925         }
 926
 927         trace_rdisc(act, from, to, ifp, p, len);
 928
 929         if (ifp == 0)
 930                 trace_pkt("unknown interface for router-discovery %s"
 931                           " from %s to %s",
 932                           type, naddr_ntoa(from), naddr_ntoa(to));
 933
 934         return ifp;
 935 }
 936
 937
 938 /* read packets from the router discovery socket
 939  */
 940 void
 941 read_d(void)
 942 {
 943         static struct msg_limit bad_asize, bad_len;
 944 #ifdef USE_PASSIFNAME
 945         static struct msg_limit  bad_name;
 946 #endif
 947         struct sockaddr_in from;
 948         int n, fromlen, cc, hlen;
 949         struct {
 950 #ifdef USE_PASSIFNAME
 951                 char    ifname[IFNAMSIZ];
 952 #endif
 953                 union {
 954                         struct ip ip;
 955                         u_short s[512/2];
 956                         u_char  b[512];
 957                 } pkt;
 958         } buf;
 959         union ad_u *p;
 960         n_long *wp;
 961         struct interface *ifp;
 962
 963
 964         for (;;) {
 965                 fromlen = sizeof(from);
 966                 cc = recvfrom(rdisc_sock, &buf, sizeof(buf), 0,
 967                               (struct sockaddr*)&from,
 968                               &fromlen);
 969                 if (cc <= 0) {
 970                         if (cc < 0 && errno != EWOULDBLOCK)
 971                                 LOGERR("recvfrom(rdisc_sock)");
 972                         break;
 973                 }
 974                 if (fromlen != sizeof(struct sockaddr_in))
 975                         logbad(1,"impossible recvfrom(rdisc_sock) fromlen=%d",
 976                                fromlen);
 977 #ifdef USE_PASSIFNAME
 978                 if ((cc -= sizeof(buf.ifname)) < 0)
 979                         logbad(0,"missing USE_PASSIFNAME; only %d bytes",
 980                                cc+sizeof(buf.ifname));
 981 #endif
 982
 983                 hlen = buf.pkt.ip.ip_hl << 2;
 984                 if (cc < hlen + ICMP_MINLEN)
 985                         continue;
 986                 p = (union ad_u *)&buf.pkt.b[hlen];
 987                 cc -= hlen;
 988
 989 #ifdef USE_PASSIFNAME
 990                 ifp = ifwithname(buf.ifname, 0);
 991                 if (ifp == 0)
 992                         msglim(&bad_name, from.sin_addr.s_addr,
 993                                "impossible rdisc if_ name %.*s",
 994                                IFNAMSIZ, buf.ifname);
 995 #else
 996                 /* If we could tell the interface on which a packet from
 997                  * address 0 arrived, we could deal with such solicitations.
 998                  */
 999                 ifp = ((from.sin_addr.s_addr == 0)
1000                        ? 0 : iflookup(from.sin_addr.s_addr));
1001 #endif
1002                 ifp = ck_icmp("Recv", from.sin_addr.s_addr, ifp,
1003                               buf.pkt.ip.ip_dst.s_addr, p, cc);
1004                 if (ifp == 0)
1005                         continue;
1006                 if (ifwithaddr(from.sin_addr.s_addr, 0, 0)) {
1007                         trace_pkt("    "
1008                                   "discard our own Router Discovery message");
1009                         continue;
1010                 }
1011
1012                 switch (p->icmp.icmp_type) {
1013                 case ICMP_ROUTERADVERT:
1014                         if (p->ad.icmp_ad_asize*4
1015                             < (int)sizeof(p->ad.icmp_ad_info[0])) {
1016                                 msglim(&bad_asize, from.sin_addr.s_addr,
1017                                        "intolerable rdisc address size=%d",
1018                                        p->ad.icmp_ad_asize);
1019                                 continue;
1020                         }
1021                         if (p->ad.icmp_ad_num == 0) {
1022                                 trace_pkt("    empty?");
1023                                 continue;
1024                         }
1025                         if (cc != (int)(sizeof(p->ad)
1026                                         - sizeof(p->ad.icmp_ad_info)
1027                                         + (p->ad.icmp_ad_num
1028                                            * sizeof(p->ad.icmp_ad_info[0])))) {
1029                                 msglim(&bad_len, from.sin_addr.s_addr,
1030                                        "rdisc length %d does not match ad_num"
1031                                        " %d", cc, p->ad.icmp_ad_num);
1032                                 continue;
1033                         }
1034                         if (supplier)
1035                                 continue;
1036                         if (ifp->int_state & IS_NO_ADV_IN)
1037                                 continue;
1038
1039                         wp = &p->ad.icmp_ad_info[0].icmp_ad_addr;
1040                         for (n = 0; n < p->ad.icmp_ad_num; n++) {
1041                                 parse_ad(from.sin_addr.s_addr,
1042                                          wp[0], wp[1],
1043                                          ntohs(p->ad.icmp_ad_life),
1044                                          ifp);
1045                                 wp += p->ad.icmp_ad_asize;
1046                         }
1047                         break;
1048
1049
1050                 case ICMP_ROUTERSOLICIT:
1051                         if (!supplier)
1052                                 continue;
1053                         if (ifp->int_state & IS_NO_ADV_OUT)
1054                                 continue;
1055                         if (stopint)
1056                                 continue;
1057
1058                         /* XXX
1059                          * We should handle messages from address 0.
1060                          */
1061
1062                         /* Respond with a point-to-point advertisement */
1063                         send_adv(ifp, from.sin_addr.s_addr, 0);
1064                         break;
1065                 }
1066         }
1067
1068         rdisc_sort();
1069 }