sbin/routed/input.c

   1 /*
   2  * Copyright (c) 1983, 1988, 1993
   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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD$
  30  */
  31
  32 #include "defs.h"
  33
  34 #ifdef __NetBSD__
  35 __RCSID("$NetBSD$");
  36 #elif defined(__FreeBSD__)
  37 __RCSID("$FreeBSD$");
  38 #else
  39 __RCSID("$Revision: 2.26 $");
  40 #ident "$Revision: 2.26 $"
  41 #endif
  42
  43 static void input(struct sockaddr_in *, struct interface *, struct interface *,
  44                   struct rip *, int);
  45 static void input_route(naddr, naddr, struct rt_spare *, struct netinfo *);
  46 static int ck_passwd(struct interface *, struct rip *, void *,
  47                      naddr, struct msg_limit *);
  48
  49
  50 /* process RIP input
  51  */
  52 void
  53 read_rip(int sock,
  54          struct interface *sifp)
  55 {
  56         struct sockaddr_in from;
  57         struct interface *aifp;
  58         socklen_t fromlen;
  59         int cc;
  60 #ifdef USE_PASSIFNAME
  61         static struct msg_limit  bad_name;
  62         struct {
  63                 char    ifname[IFNAMSIZ];
  64                 union pkt_buf pbuf;
  65         } inbuf;
  66 #else
  67         struct {
  68                 union pkt_buf pbuf;
  69         } inbuf;
  70 #endif
  71
  72
  73         for (;;) {
  74                 fromlen = sizeof(from);
  75                 cc = recvfrom(sock, &inbuf, sizeof(inbuf), 0,
  76                               (struct sockaddr*)&from, &fromlen);
  77                 if (cc <= 0) {
  78                         if (cc < 0 && errno != EWOULDBLOCK)
  79                                 LOGERR("recvfrom(rip)");
  80                         break;
  81                 }
  82                 if (fromlen != sizeof(struct sockaddr_in))
  83                         logbad(1,"impossible recvfrom(rip) fromlen=%d",
  84                                (int)fromlen);
  85
  86                 /* aifp is the "authenticated" interface via which the packet
  87                  *      arrived.  In fact, it is only the interface on which
  88                  *      the packet should have arrived based on is source
  89                  *      address.
  90                  * sifp is interface associated with the socket through which
  91                  *      the packet was received.
  92                  */
  93 #ifdef USE_PASSIFNAME
  94                 if ((cc -= sizeof(inbuf.ifname)) < 0)
  95                         logbad(0,"missing USE_PASSIFNAME; only %d bytes",
  96                                cc+sizeof(inbuf.ifname));
  97
  98                 /* check the remote interfaces first */
  99                 LIST_FOREACH(aifp, &remote_if, remote_list) {
 100                         if (aifp->int_addr == from.sin_addr.s_addr)
 101                                 break;
 102                 }
 103                 if (aifp == 0) {
 104                         aifp = ifwithname(inbuf.ifname, 0);
 105                         if (aifp == 0) {
 106                                 msglim(&bad_name, from.sin_addr.s_addr,
 107                                        "impossible interface name %.*s",
 108                                        IFNAMSIZ, inbuf.ifname);
 109                         } else if (((aifp->int_if_flags & IFF_POINTOPOINT)
 110                                     && aifp->int_dstaddr!=from.sin_addr.s_addr)
 111                                    || (!(aifp->int_if_flags & IFF_POINTOPOINT)
 112                                        && !on_net(from.sin_addr.s_addr,
 113                                                   aifp->int_net,
 114                                                   aifp->int_mask))) {
 115                                 /* If it came via the wrong interface, do not
 116                                  * trust it.
 117                                  */
 118                                 aifp = 0;
 119                         }
 120                 }
 121 #else
 122                 aifp = iflookup(from.sin_addr.s_addr);
 123 #endif
 124                 if (sifp == 0)
 125                         sifp = aifp;
 126
 127                 input(&from, sifp, aifp, &inbuf.pbuf.rip, cc);
 128         }
 129 }
 130
 131
 132 /* Process a RIP packet
 133  */
 134 static void
 135 input(struct sockaddr_in *from,         /* received from this IP address */
 136       struct interface *sifp,           /* interface of incoming socket */
 137       struct interface *aifp,           /* "authenticated" interface */
 138       struct rip *rip,
 139       int cc)
 140 {
 141 #       define FROM_NADDR from->sin_addr.s_addr
 142         static struct msg_limit use_auth, bad_len, bad_mask;
 143         static struct msg_limit unk_router, bad_router, bad_nhop;
 144
 145         struct rt_entry *rt;
 146         struct rt_spare new;
 147         struct netinfo *n, *lim;
 148         struct interface *ifp1;
 149         naddr gate, mask, v1_mask, dst, ddst_h = 0;
 150         struct auth *ap;
 151         struct tgate *tg = 0;
 152         struct tgate_net *tn;
 153         int i, j;
 154
 155         /* Notice when we hear from a remote gateway
 156          */
 157         if (aifp != 0
 158             && (aifp->int_state & IS_REMOTE))
 159                 aifp->int_act_time = now.tv_sec;
 160
 161         trace_rip("Recv", "from", from, sifp, rip, cc);
 162
 163         if (rip->rip_vers == 0) {
 164                 msglim(&bad_router, FROM_NADDR,
 165                        "RIP version 0, cmd %d, packet received from %s",
 166                        rip->rip_cmd, naddr_ntoa(FROM_NADDR));
 167                 return;
 168         } else if (rip->rip_vers > RIPv2) {
 169                 rip->rip_vers = RIPv2;
 170         }
 171         if (cc > (int)OVER_MAXPACKETSIZE) {
 172                 msglim(&bad_router, FROM_NADDR,
 173                        "packet at least %d bytes too long received from %s",
 174                        cc-MAXPACKETSIZE, naddr_ntoa(FROM_NADDR));
 175                 return;
 176         }
 177
 178         n = rip->rip_nets;
 179         lim = (struct netinfo *)((char*)rip + cc);
 180
 181         /* Notice authentication.
 182          * As required by section 4.2 in RFC 1723, discard authenticated
 183          * RIPv2 messages, but only if configured for that silliness.
 184          *
 185          * RIPv2 authentication is lame.  Why authenticate queries?
 186          * Why should a RIPv2 implementation with authentication disabled
 187          * not be able to listen to RIPv2 packets with authentication, while
 188          * RIPv1 systems will listen?  Crazy!
 189          */
 190         if (!auth_ok
 191             && rip->rip_vers == RIPv2
 192             && n < lim && n->n_family == RIP_AF_AUTH) {
 193                 msglim(&use_auth, FROM_NADDR,
 194                        "RIPv2 message with authentication from %s discarded",
 195                        naddr_ntoa(FROM_NADDR));
 196                 return;
 197         }
 198
 199         switch (rip->rip_cmd) {
 200         case RIPCMD_REQUEST:
 201                 /* For mere requests, be a little sloppy about the source
 202                  */
 203                 if (aifp == 0)
 204                         aifp = sifp;
 205
 206                 /* Are we talking to ourself or a remote gateway?
 207                  */
 208                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 209                 if (ifp1) {
 210                         if (ifp1->int_state & IS_REMOTE) {
 211                                 /* remote gateway */
 212                                 aifp = ifp1;
 213                                 if (check_remote(aifp)) {
 214                                         aifp->int_act_time = now.tv_sec;
 215                                         (void)if_ok(aifp, "remote ");
 216                                 }
 217                         } else if (from->sin_port == htons(RIP_PORT)) {
 218                                 trace_pkt("    discard our own RIP request");
 219                                 return;
 220                         }
 221                 }
 222
 223                 /* did the request come from a router?
 224                  */
 225                 if (from->sin_port == htons(RIP_PORT)) {
 226                         /* yes, ignore the request if RIP is off so that
 227                          * the router does not depend on us.
 228                          */
 229                         if (rip_sock < 0
 230                             || (aifp != 0
 231                                 && IS_RIP_OUT_OFF(aifp->int_state))) {
 232                                 trace_pkt("    discard request while RIP off");
 233                                 return;
 234                         }
 235                 }
 236
 237                 /* According to RFC 1723, we should ignore unauthenticated
 238                  * queries.  That is too silly to bother with.  Sheesh!
 239                  * Are forwarding tables supposed to be secret, when
 240                  * a bad guy can infer them with test traffic?  When RIP
 241                  * is still the most common router-discovery protocol
 242                  * and so hosts need to send queries that will be answered?
 243                  * What about `rtquery`?
 244                  * Maybe on firewalls you'd care, but not enough to
 245                  * give up the diagnostic facilities of remote probing.
 246                  */
 247
 248                 if (n >= lim) {
 249                         msglim(&bad_len, FROM_NADDR, "empty request from %s",
 250                                naddr_ntoa(FROM_NADDR));
 251                         return;
 252                 }
 253                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 254                         msglim(&bad_len, FROM_NADDR,
 255                                "request of bad length (%d) from %s",
 256                                cc, naddr_ntoa(FROM_NADDR));
 257                 }
 258
 259                 if (rip->rip_vers == RIPv2
 260                     && (aifp == 0 || (aifp->int_state & IS_NO_RIPV1_OUT))) {
 261                         v12buf.buf->rip_vers = RIPv2;
 262                         /* If we have a secret but it is a cleartext secret,
 263                          * do not disclose our secret unless the other guy
 264                          * already knows it.
 265                          */
 266                         ap = find_auth(aifp);
 267                         if (ap != 0 && ap->type == RIP_AUTH_PW
 268                             && n->n_family == RIP_AF_AUTH
 269                             && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 270                                 ap = 0;
 271                 } else {
 272                         v12buf.buf->rip_vers = RIPv1;
 273                         ap = 0;
 274                 }
 275                 clr_ws_buf(&v12buf, ap);
 276
 277                 do {
 278                         n->n_metric = ntohl(n->n_metric);
 279
 280                         /* A single entry with family RIP_AF_UNSPEC and
 281                          * metric HOPCNT_INFINITY means "all routes".
 282                          * We respond to routers only if we are acting
 283                          * as a supplier, or to anyone other than a router
 284                          * (i.e. a query).
 285                          */
 286                         if (n->n_family == RIP_AF_UNSPEC
 287                             && n->n_metric == HOPCNT_INFINITY) {
 288                                 /* Answer a query from a utility program
 289                                  * with all we know.
 290                                  */
 291                                 if (from->sin_port != htons(RIP_PORT)) {
 292                                         supply(from, aifp, OUT_QUERY, 0,
 293                                                rip->rip_vers, ap != 0);
 294                                         return;
 295                                 }
 296
 297                                 /* A router trying to prime its tables.
 298                                  * Filter the answer in the about same way
 299                                  * broadcasts are filtered.
 300                                  *
 301                                  * Only answer a router if we are a supplier
 302                                  * to keep an unwary host that is just starting
 303                                  * from picking us as a router.
 304                                  */
 305                                 if (aifp == 0) {
 306                                         trace_pkt("ignore distant router");
 307                                         return;
 308                                 }
 309                                 if (!supplier
 310                                     || IS_RIP_OFF(aifp->int_state)) {
 311                                         trace_pkt("ignore; not supplying");
 312                                         return;
 313                                 }
 314
 315                                 /* Do not answer a RIPv1 router if
 316                                  * we are sending RIPv2.  But do offer
 317                                  * poor man's router discovery.
 318                                  */
 319                                 if ((aifp->int_state & IS_NO_RIPV1_OUT)
 320                                     && rip->rip_vers == RIPv1) {
 321                                         if (!(aifp->int_state & IS_PM_RDISC)) {
 322                                             trace_pkt("ignore; sending RIPv2");
 323                                             return;
 324                                         }
 325
 326                                         v12buf.n->n_family = RIP_AF_INET;
 327                                         v12buf.n->n_dst = RIP_DEFAULT;
 328                                         i = aifp->int_d_metric;
 329                                         if (0 != (rt = rtget(RIP_DEFAULT, 0))) {
 330                                             j = (rt->rt_metric
 331                                                  +aifp->int_metric
 332                                                  +aifp->int_adj_outmetric
 333                                                  +1);
 334                                             if (i > j)
 335                                                 i = j;
 336                                         }
 337                                         v12buf.n->n_metric = htonl(i);
 338                                         v12buf.n++;
 339                                         break;
 340                                 }
 341
 342                                 /* Respond with RIPv1 instead of RIPv2 if
 343                                  * that is what we are broadcasting on the
 344                                  * interface to keep the remote router from
 345                                  * getting the wrong initial idea of the
 346                                  * routes we send.
 347                                  */
 348                                 supply(from, aifp, OUT_UNICAST, 0,
 349                                        (aifp->int_state & IS_NO_RIPV1_OUT)
 350                                        ? RIPv2 : RIPv1,
 351                                        ap != 0);
 352                                 return;
 353                         }
 354
 355                         /* Ignore authentication */
 356                         if (n->n_family == RIP_AF_AUTH)
 357                                 continue;
 358
 359                         if (n->n_family != RIP_AF_INET) {
 360                                 msglim(&bad_router, FROM_NADDR,
 361                                        "request from %s for unsupported"
 362                                        " (af %d) %s",
 363                                        naddr_ntoa(FROM_NADDR),
 364                                        ntohs(n->n_family),
 365                                        naddr_ntoa(n->n_dst));
 366                                 return;
 367                         }
 368
 369                         /* We are being asked about a specific destination.
 370                          */
 371                         dst = n->n_dst;
 372                         if (!check_dst(dst)) {
 373                                 msglim(&bad_router, FROM_NADDR,
 374                                        "bad queried destination %s from %s",
 375                                        naddr_ntoa(dst),
 376                                        naddr_ntoa(FROM_NADDR));
 377                                 return;
 378                         }
 379
 380                         /* decide what mask was intended */
 381                         if (rip->rip_vers == RIPv1
 382                             || 0 == (mask = ntohl(n->n_mask))
 383                             || 0 != (ntohl(dst) & ~mask))
 384                                 mask = ripv1_mask_host(dst, aifp);
 385
 386                         /* try to find the answer */
 387                         rt = rtget(dst, mask);
 388                         if (!rt && dst != RIP_DEFAULT)
 389                                 rt = rtfind(n->n_dst);
 390
 391                         if (v12buf.buf->rip_vers != RIPv1)
 392                                 v12buf.n->n_mask = mask;
 393                         if (rt == 0) {
 394                                 /* we do not have the answer */
 395                                 v12buf.n->n_metric = HOPCNT_INFINITY;
 396                         } else {
 397                                 /* we have the answer, so compute the
 398                                  * right metric and next hop.
 399                                  */
 400                                 v12buf.n->n_family = RIP_AF_INET;
 401                                 v12buf.n->n_dst = dst;
 402                                 j = rt->rt_metric+1;
 403                                 if (!aifp)
 404                                         ++j;
 405                                 else
 406                                         j += (aifp->int_metric
 407                                               + aifp->int_adj_outmetric);
 408                                 if (j < HOPCNT_INFINITY)
 409                                         v12buf.n->n_metric = j;
 410                                 else
 411                                         v12buf.n->n_metric = HOPCNT_INFINITY;
 412                                 if (v12buf.buf->rip_vers != RIPv1) {
 413                                         v12buf.n->n_tag = rt->rt_tag;
 414                                         v12buf.n->n_mask = mask;
 415                                         if (aifp != 0
 416                                             && on_net(rt->rt_gate,
 417                                                       aifp->int_net,
 418                                                       aifp->int_mask)
 419                                             && rt->rt_gate != aifp->int_addr)
 420                                             v12buf.n->n_nhop = rt->rt_gate;
 421                                 }
 422                         }
 423                         v12buf.n->n_metric = htonl(v12buf.n->n_metric);
 424
 425                         /* Stop paying attention if we fill the output buffer.
 426                          */
 427                         if (++v12buf.n >= v12buf.lim)
 428                                 break;
 429                 } while (++n < lim);
 430
 431                 /* Send the answer about specific routes.
 432                  */
 433                 if (ap != 0 && ap->type == RIP_AUTH_MD5)
 434                         end_md5_auth(&v12buf, ap);
 435
 436                 if (from->sin_port != htons(RIP_PORT)) {
 437                         /* query */
 438                         (void)output(OUT_QUERY, from, aifp,
 439                                      v12buf.buf,
 440                                      ((char *)v12buf.n - (char*)v12buf.buf));
 441                 } else if (supplier) {
 442                         (void)output(OUT_UNICAST, from, aifp,
 443                                      v12buf.buf,
 444                                      ((char *)v12buf.n - (char*)v12buf.buf));
 445                 } else {
 446                         /* Only answer a router if we are a supplier
 447                          * to keep an unwary host that is just starting
 448                          * from picking us an a router.
 449                          */
 450                         ;
 451                 }
 452                 return;
 453
 454         case RIPCMD_TRACEON:
 455         case RIPCMD_TRACEOFF:
 456                 /* Notice that trace messages are turned off for all possible
 457                  * abuse if _PATH_TRACE is undefined in pathnames.h.
 458                  * Notice also that because of the way the trace file is
 459                  * handled in trace.c, no abuse is plausible even if
 460                  * _PATH_TRACE_ is defined.
 461                  *
 462                  * First verify message came from a privileged port. */
 463                 if (ntohs(from->sin_port) > IPPORT_RESERVED) {
 464                         msglog("trace command from untrusted port on %s",
 465                                naddr_ntoa(FROM_NADDR));
 466                         return;
 467                 }
 468                 if (aifp == 0) {
 469                         msglog("trace command from unknown router %s",
 470                                naddr_ntoa(FROM_NADDR));
 471                         return;
 472                 }
 473                 if (rip->rip_cmd == RIPCMD_TRACEON) {
 474                         rip->rip_tracefile[cc-4] = '\0';
 475                         set_tracefile((char*)rip->rip_tracefile,
 476                                       "trace command: %s\n", 0);
 477                 } else {
 478                         trace_off("tracing turned off by %s",
 479                                   naddr_ntoa(FROM_NADDR));
 480                 }
 481                 return;
 482
 483         case RIPCMD_RESPONSE:
 484                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 485                         msglim(&bad_len, FROM_NADDR,
 486                                "response of bad length (%d) from %s",
 487                                cc, naddr_ntoa(FROM_NADDR));
 488                 }
 489
 490                 /* verify message came from a router */
 491                 if (from->sin_port != ntohs(RIP_PORT)) {
 492                         msglim(&bad_router, FROM_NADDR,
 493                                "    discard RIP response from unknown port"
 494                                " %d on %s",
 495                                ntohs(from->sin_port), naddr_ntoa(FROM_NADDR));
 496                         return;
 497                 }
 498
 499                 if (rip_sock < 0) {
 500                         trace_pkt("    discard response while RIP off");
 501                         return;
 502                 }
 503
 504                 /* Are we talking to ourself or a remote gateway?
 505                  */
 506                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 507                 if (ifp1) {
 508                         if (ifp1->int_state & IS_REMOTE) {
 509                                 /* remote gateway */
 510                                 aifp = ifp1;
 511                                 if (check_remote(aifp)) {
 512                                         aifp->int_act_time = now.tv_sec;
 513                                         (void)if_ok(aifp, "remote ");
 514                                 }
 515                         } else {
 516                                 trace_pkt("    discard our own RIP response");
 517                                 return;
 518                         }
 519                 }
 520
 521                 /* Accept routing packets from routers directly connected
 522                  * via broadcast or point-to-point networks, and from
 523                  * those listed in /etc/gateways.
 524                  */
 525                 if (aifp == 0) {
 526                         msglim(&unk_router, FROM_NADDR,
 527                                "   discard response from %s"
 528                                " via unexpected interface",
 529                                naddr_ntoa(FROM_NADDR));
 530                         return;
 531                 }
 532                 if (IS_RIP_IN_OFF(aifp->int_state)) {
 533                         trace_pkt("    discard RIPv%d response"
 534                                   " via disabled interface %s",
 535                                   rip->rip_vers, aifp->int_name);
 536                         return;
 537                 }
 538
 539                 if (n >= lim) {
 540                         msglim(&bad_len, FROM_NADDR, "empty response from %s",
 541                                naddr_ntoa(FROM_NADDR));
 542                         return;
 543                 }
 544
 545                 if (((aifp->int_state & IS_NO_RIPV1_IN)
 546                      && rip->rip_vers == RIPv1)
 547                     || ((aifp->int_state & IS_NO_RIPV2_IN)
 548                         && rip->rip_vers != RIPv1)) {
 549                         trace_pkt("    discard RIPv%d response",
 550                                   rip->rip_vers);
 551                         return;
 552                 }
 553
 554                 /* Ignore routes via dead interface.
 555                  */
 556                 if (aifp->int_state & IS_BROKE) {
 557                         trace_pkt("discard response via broken interface %s",
 558                                   aifp->int_name);
 559                         return;
 560                 }
 561
 562                 /* If the interface cares, ignore bad routers.
 563                  * Trace but do not log this problem, because where it
 564                  * happens, it happens frequently.
 565                  */
 566                 if (aifp->int_state & IS_DISTRUST) {
 567                         tg = tgates;
 568                         while (tg->tgate_addr != FROM_NADDR) {
 569                                 tg = tg->tgate_next;
 570                                 if (tg == 0) {
 571                                         trace_pkt("    discard RIP response"
 572                                                   " from untrusted router %s",
 573                                                   naddr_ntoa(FROM_NADDR));
 574                                         return;
 575                                 }
 576                         }
 577                 }
 578
 579                 /* Authenticate the packet if we have a secret.
 580                  * If we do not have any secrets, ignore the error in
 581                  * RFC 1723 and accept it regardless.
 582                  */
 583                 if (aifp->int_auth[0].type != RIP_AUTH_NONE
 584                     && rip->rip_vers != RIPv1
 585                     && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 586                         return;
 587
 588                 do {
 589                         if (n->n_family == RIP_AF_AUTH)
 590                                 continue;
 591
 592                         n->n_metric = ntohl(n->n_metric);
 593                         dst = n->n_dst;
 594                         if (n->n_family != RIP_AF_INET
 595                             && (n->n_family != RIP_AF_UNSPEC
 596                                 || dst != RIP_DEFAULT)) {
 597                                 msglim(&bad_router, FROM_NADDR,
 598                                        "route from %s to unsupported"
 599                                        " address family=%d destination=%s",
 600                                        naddr_ntoa(FROM_NADDR),
 601                                        n->n_family,
 602                                        naddr_ntoa(dst));
 603                                 continue;
 604                         }
 605                         if (!check_dst(dst)) {
 606                                 msglim(&bad_router, FROM_NADDR,
 607                                        "bad destination %s from %s",
 608                                        naddr_ntoa(dst),
 609                                        naddr_ntoa(FROM_NADDR));
 610                                 return;
 611                         }
 612                         if (n->n_metric == 0
 613                             || n->n_metric > HOPCNT_INFINITY) {
 614                                 msglim(&bad_router, FROM_NADDR,
 615                                        "bad metric %d from %s"
 616                                        " for destination %s",
 617                                        n->n_metric,
 618                                        naddr_ntoa(FROM_NADDR),
 619                                        naddr_ntoa(dst));
 620                                 return;
 621                         }
 622
 623                         /* Notice the next-hop.
 624                          */
 625                         gate = FROM_NADDR;
 626                         if (n->n_nhop != 0) {
 627                                 if (rip->rip_vers == RIPv1) {
 628                                         n->n_nhop = 0;
 629                                 } else {
 630                                     /* Use it only if it is valid. */
 631                                     if (on_net(n->n_nhop,
 632                                                aifp->int_net, aifp->int_mask)
 633                                         && check_dst(n->n_nhop)) {
 634                                             gate = n->n_nhop;
 635                                     } else {
 636                                             msglim(&bad_nhop, FROM_NADDR,
 637                                                    "router %s to %s"
 638                                                    " has bad next hop %s",
 639                                                    naddr_ntoa(FROM_NADDR),
 640                                                    naddr_ntoa(dst),
 641                                                    naddr_ntoa(n->n_nhop));
 642                                             n->n_nhop = 0;
 643                                     }
 644                                 }
 645                         }
 646
 647                         if (rip->rip_vers == RIPv1
 648                             || 0 == (mask = ntohl(n->n_mask))) {
 649                                 mask = ripv1_mask_host(dst,aifp);
 650                         } else if ((ntohl(dst) & ~mask) != 0) {
 651                                 msglim(&bad_mask, FROM_NADDR,
 652                                        "router %s sent bad netmask"
 653                                        " %#lx with %s",
 654                                        naddr_ntoa(FROM_NADDR),
 655                                        (u_long)mask,
 656                                        naddr_ntoa(dst));
 657                                 continue;
 658                         }
 659                         if (rip->rip_vers == RIPv1)
 660                                 n->n_tag = 0;
 661
 662                         /* Adjust metric according to incoming interface..
 663                          */
 664                         n->n_metric += (aifp->int_metric
 665                                         + aifp->int_adj_inmetric);
 666                         if (n->n_metric > HOPCNT_INFINITY)
 667                                 n->n_metric = HOPCNT_INFINITY;
 668
 669                         /* Should we trust this route from this router? */
 670                         if (tg && (tn = tg->tgate_nets)->mask != 0) {
 671                                 for (i = 0; i < MAX_TGATE_NETS; i++, tn++) {
 672                                         if (on_net(dst, tn->net, tn->mask)
 673                                             && tn->mask <= mask)
 674                                             break;
 675                                 }
 676                                 if (i >= MAX_TGATE_NETS || tn->mask == 0) {
 677                                         trace_pkt("   ignored unauthorized %s",
 678                                                   addrname(dst,mask,0));
 679                                         continue;
 680                                 }
 681                         }
 682
 683                         /* Recognize and ignore a default route we faked
 684                          * which is being sent back to us by a machine with
 685                          * broken split-horizon.
 686                          * Be a little more paranoid than that, and reject
 687                          * default routes with the same metric we advertised.
 688                          */
 689                         if (aifp->int_d_metric != 0
 690                             && dst == RIP_DEFAULT
 691                             && (int)n->n_metric >= aifp->int_d_metric)
 692                                 continue;
 693
 694                         /* We can receive aggregated RIPv2 routes that must
 695                          * be broken down before they are transmitted by
 696                          * RIPv1 via an interface on a subnet.
 697                          * We might also receive the same routes aggregated
 698                          * via other RIPv2 interfaces.
 699                          * This could cause duplicate routes to be sent on
 700                          * the RIPv1 interfaces.  "Longest matching variable
 701                          * length netmasks" lets RIPv2 listeners understand,
 702                          * but breaking down the aggregated routes for RIPv1
 703                          * listeners can produce duplicate routes.
 704                          *
 705                          * Breaking down aggregated routes here bloats
 706                          * the daemon table, but does not hurt the kernel
 707                          * table, since routes are always aggregated for
 708                          * the kernel.
 709                          *
 710                          * Notice that this does not break down network
 711                          * routes corresponding to subnets.  This is part
 712                          * of the defense against RS_NET_SYN.
 713                          */
 714                         if (have_ripv1_out
 715                             && (((rt = rtget(dst,mask)) == 0
 716                                  || !(rt->rt_state & RS_NET_SYN)))
 717                             && (v1_mask = ripv1_mask_net(dst,0)) > mask) {
 718                                 ddst_h = v1_mask & -v1_mask;
 719                                 i = (v1_mask & ~mask)/ddst_h;
 720                                 if (i >= 511) {
 721                                         /* Punt if we would have to generate
 722                                          * an unreasonable number of routes.
 723                                          */
 724                                         if (TRACECONTENTS)
 725                                             trace_misc("accept %s-->%s as 1"
 726                                                        " instead of %d routes",
 727                                                        addrname(dst,mask,0),
 728                                                        naddr_ntoa(FROM_NADDR),
 729                                                        i+1);
 730                                         i = 0;
 731                                 } else {
 732                                         mask = v1_mask;
 733                                 }
 734                         } else {
 735                                 i = 0;
 736                         }
 737
 738                         new.rts_gate = gate;
 739                         new.rts_router = FROM_NADDR;
 740                         new.rts_metric = n->n_metric;
 741                         new.rts_tag = n->n_tag;
 742                         new.rts_time = now.tv_sec;
 743                         new.rts_ifp = aifp;
 744                         new.rts_de_ag = i;
 745                         j = 0;
 746                         for (;;) {
 747                                 input_route(dst, mask, &new, n);
 748                                 if (++j > i)
 749                                         break;
 750                                 dst = htonl(ntohl(dst) + ddst_h);
 751                         }
 752                 } while (++n < lim);
 753                 break;
 754         }
 755 #undef FROM_NADDR
 756 }
 757
 758
 759 /* Process a single input route.
 760  */
 761 static void
 762 input_route(naddr dst,                  /* network order */
 763             naddr mask,
 764             struct rt_spare *new,
 765             struct netinfo *n)
 766 {
 767         int i;
 768         struct rt_entry *rt;
 769         struct rt_spare *rts, *rts0;
 770         struct interface *ifp1;
 771
 772
 773         /* See if the other guy is telling us to send our packets to him.
 774          * Sometimes network routes arrive over a point-to-point link for
 775          * the network containing the address(es) of the link.
 776          *
 777          * If our interface is broken, switch to using the other guy.
 778          */
 779         ifp1 = ifwithaddr(dst, 1, 1);
 780         if (ifp1 != 0
 781             && (!(ifp1->int_state & IS_BROKE)
 782                 || (ifp1->int_state & IS_PASSIVE)))
 783                 return;
 784
 785         /* Look for the route in our table.
 786          */
 787         rt = rtget(dst, mask);
 788
 789         /* Consider adding the route if we do not already have it.
 790          */
 791         if (rt == 0) {
 792                 /* Ignore unknown routes being poisoned.
 793                  */
 794                 if (new->rts_metric == HOPCNT_INFINITY)
 795                         return;
 796
 797                 /* Ignore the route if it points to us */
 798                 if (n->n_nhop != 0
 799                     && 0 != ifwithaddr(n->n_nhop, 1, 0))
 800                         return;
 801
 802                 /* If something has not gone crazy and tried to fill
 803                  * our memory, accept the new route.
 804                  */
 805                 if (total_routes < MAX_ROUTES)
 806                         rtadd(dst, mask, 0, new);
 807                 return;
 808         }
 809
 810         /* We already know about the route.  Consider this update.
 811          *
 812          * If (rt->rt_state & RS_NET_SYN), then this route
 813          * is the same as a network route we have inferred
 814          * for subnets we know, in order to tell RIPv1 routers
 815          * about the subnets.
 816          *
 817          * It is impossible to tell if the route is coming
 818          * from a distant RIPv2 router with the standard
 819          * netmask because that router knows about the entire
 820          * network, or if it is a round-about echo of a
 821          * synthetic, RIPv1 network route of our own.
 822          * The worst is that both kinds of routes might be
 823          * received, and the bad one might have the smaller
 824          * metric.  Partly solve this problem by never
 825          * aggregating into such a route.  Also keep it
 826          * around as long as the interface exists.
 827          */
 828
 829         rts0 = rt->rt_spares;
 830         for (rts = rts0, i = NUM_SPARES; i != 0; i--, rts++) {
 831                 if (rts->rts_router == new->rts_router)
 832                         break;
 833                 /* Note the worst slot to reuse,
 834                  * other than the current slot.
 835                  */
 836                 if (rts0 == rt->rt_spares
 837                     || BETTER_LINK(rt, rts0, rts))
 838                         rts0 = rts;
 839         }
 840         if (i != 0) {
 841                 /* Found a route from the router already in the table.
 842                  */
 843
 844                 /* If the new route is a route broken down from an
 845                  * aggregated route, and if the previous route is either
 846                  * not a broken down route or was broken down from a finer
 847                  * netmask, and if the previous route is current,
 848                  * then forget this one.
 849                  */
 850                 if (new->rts_de_ag > rts->rts_de_ag
 851                     && now_stale <= rts->rts_time)
 852                         return;
 853
 854                 /* Keep poisoned routes around only long enough to pass
 855                  * the poison on.  Use a new timestamp for good routes.
 856                  */
 857                 if (rts->rts_metric == HOPCNT_INFINITY
 858                     && new->rts_metric == HOPCNT_INFINITY)
 859                         new->rts_time = rts->rts_time;
 860
 861                 /* If this is an update for the router we currently prefer,
 862                  * then note it.
 863                  */
 864                 if (i == NUM_SPARES) {
 865                         rtchange(rt, rt->rt_state, new, 0);
 866                         /* If the route got worse, check for something better.
 867                          */
 868                         if (new->rts_metric > rts->rts_metric)
 869                                 rtswitch(rt, 0);
 870                         return;
 871                 }
 872
 873                 /* This is an update for a spare route.
 874                  * Finished if the route is unchanged.
 875                  */
 876                 if (rts->rts_gate == new->rts_gate
 877                     && rts->rts_metric == new->rts_metric
 878                     && rts->rts_tag == new->rts_tag) {
 879                         trace_upslot(rt, rts, new);
 880                         *rts = *new;
 881                         return;
 882                 }
 883                 /* Forget it if it has gone bad.
 884                  */
 885                 if (new->rts_metric == HOPCNT_INFINITY) {
 886                         rts_delete(rt, rts);
 887                         return;
 888                 }
 889
 890         } else {
 891                 /* The update is for a route we know about,
 892                  * but not from a familiar router.
 893                  *
 894                  * Ignore the route if it points to us.
 895                  */
 896                 if (n->n_nhop != 0
 897                     && 0 != ifwithaddr(n->n_nhop, 1, 0))
 898                         return;
 899
 900                 /* the loop above set rts0=worst spare */
 901                 rts = rts0;
 902
 903                 /* Save the route as a spare only if it has
 904                  * a better metric than our worst spare.
 905                  * This also ignores poisoned routes (those
 906                  * received with metric HOPCNT_INFINITY).
 907                  */
 908                 if (new->rts_metric >= rts->rts_metric)
 909                         return;
 910         }
 911
 912         trace_upslot(rt, rts, new);
 913         *rts = *new;
 914
 915         /* try to switch to a better route */
 916         rtswitch(rt, rts);
 917 }
 918
 919
 920 static int                              /* 0 if bad */
 921 ck_passwd(struct interface *aifp,
 922           struct rip *rip,
 923           void *lim,
 924           naddr from,
 925           struct msg_limit *use_authp)
 926 {
 927 #       define NA (rip->rip_auths)
 928         struct netauth *na2;
 929         struct auth *ap;
 930         MD5_CTX md5_ctx;
 931         u_char hash[RIP_AUTH_PW_LEN];
 932         int i, len;
 933
 934         assert(aifp != NULL);
 935         if ((void *)NA >= lim || NA->a_family != RIP_AF_AUTH) {
 936                 msglim(use_authp, from, "missing password from %s",
 937                        naddr_ntoa(from));
 938                 return 0;
 939         }
 940
 941         /* accept any current (+/- 24 hours) password
 942          */
 943         for (ap = aifp->int_auth, i = 0; i < MAX_AUTH_KEYS; i++, ap++) {
 944                 if (ap->type != NA->a_type
 945                     || (u_long)ap->start > (u_long)clk.tv_sec+DAY
 946                     || (u_long)ap->end+DAY < (u_long)clk.tv_sec)
 947                         continue;
 948
 949                 if (NA->a_type == RIP_AUTH_PW) {
 950                         if (!memcmp(NA->au.au_pw, ap->key, RIP_AUTH_PW_LEN))
 951                                 return 1;
 952
 953                 } else {
 954                         /* accept MD5 secret with the right key ID
 955                          */
 956                         if (NA->au.a_md5.md5_keyid != ap->keyid)
 957                                 continue;
 958
 959                         len = ntohs(NA->au.a_md5.md5_pkt_len);
 960                         if ((len-sizeof(*rip)) % sizeof(*NA) != 0
 961                             || len != (char *)lim-(char*)rip-(int)sizeof(*NA)) {
 962                                 msglim(use_authp, from,
 963                                        "wrong MD5 RIPv2 packet length of %d"
 964                                        " instead of %d from %s",
 965                                        len, (int)((char *)lim-(char *)rip
 966                                                   -sizeof(*NA)),
 967                                        naddr_ntoa(from));
 968                                 return 0;
 969                         }
 970                         na2 = (struct netauth *)((char *)rip+len);
 971
 972                         /* Given a good hash value, these are not security
 973                          * problems so be generous and accept the routes,
 974                          * after complaining.
 975                          */
 976                         if (TRACEPACKETS) {
 977                                 if (NA->au.a_md5.md5_auth_len
 978                                     != RIP_AUTH_MD5_HASH_LEN)
 979                                         msglim(use_authp, from,
 980                                                "unknown MD5 RIPv2 auth len %#x"
 981                                                " instead of %#x from %s",
 982                                                NA->au.a_md5.md5_auth_len,
 983                                                (unsigned)RIP_AUTH_MD5_HASH_LEN,
 984                                                naddr_ntoa(from));
 985                                 if (na2->a_family != RIP_AF_AUTH)
 986                                         msglim(use_authp, from,
 987                                                "unknown MD5 RIPv2 family %#x"
 988                                                " instead of %#x from %s",
 989                                                na2->a_family, RIP_AF_AUTH,
 990                                                naddr_ntoa(from));
 991                                 if (na2->a_type != ntohs(1))
 992                                         msglim(use_authp, from,
 993                                                "MD5 RIPv2 hash has %#x"
 994                                                " instead of %#x from %s",
 995                                                na2->a_type, ntohs(1),
 996                                                naddr_ntoa(from));
 997                         }
 998
 999                         MD5Init(&md5_ctx);
1000                         MD5Update(&md5_ctx, (u_char *)rip,
1001                                   len + RIP_AUTH_MD5_HASH_XTRA);
1002                         MD5Update(&md5_ctx, ap->key, RIP_AUTH_MD5_KEY_LEN);
1003                         MD5Final(hash, &md5_ctx);
1004                         if (!memcmp(hash, na2->au.au_pw, sizeof(hash)))
1005                                 return 1;
1006                 }
1007         }
1008
1009         msglim(use_authp, from, "bad password from %s",
1010                naddr_ntoa(from));
1011         return 0;
1012 #undef NA
1013 }