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 (aifp == NULL) {
 292                                         trace_pkt("ignore remote query");
 293                                         return;
 294                                 }
 295                                 if (from->sin_port != htons(RIP_PORT)) {
 296                                         /*
 297                                          * insecure: query from non-router node
 298                                          *   > 1: allow from distant node
 299                                          *   > 0: allow from neighbor node
 300                                          *  == 0: deny
 301                                          */
 302                                         if ((aifp != NULL && insecure > 0) ||
 303                                             (aifp == NULL && insecure > 1))
 304                                                 supply(from, aifp, OUT_QUERY, 0,
 305                                                        rip->rip_vers, ap != 0);
 306                                         else
 307                                                 trace_pkt("Warning: "
 308                                                     "possible attack detected");
 309                                         return;
 310                                 }
 311
 312                                 /* A router trying to prime its tables.
 313                                  * Filter the answer in the about same way
 314                                  * broadcasts are filtered.
 315                                  *
 316                                  * Only answer a router if we are a supplier
 317                                  * to keep an unwary host that is just starting
 318                                  * from picking us as a router.
 319                                  */
 320                                 if (aifp == 0) {
 321                                         trace_pkt("ignore distant router");
 322                                         return;
 323                                 }
 324                                 if (!supplier
 325                                     || IS_RIP_OFF(aifp->int_state)) {
 326                                         trace_pkt("ignore; not supplying");
 327                                         return;
 328                                 }
 329
 330                                 /* Do not answer a RIPv1 router if
 331                                  * we are sending RIPv2.  But do offer
 332                                  * poor man's router discovery.
 333                                  */
 334                                 if ((aifp->int_state & IS_NO_RIPV1_OUT)
 335                                     && rip->rip_vers == RIPv1) {
 336                                         if (!(aifp->int_state & IS_PM_RDISC)) {
 337                                             trace_pkt("ignore; sending RIPv2");
 338                                             return;
 339                                         }
 340
 341                                         v12buf.n->n_family = RIP_AF_INET;
 342                                         v12buf.n->n_dst = RIP_DEFAULT;
 343                                         i = aifp->int_d_metric;
 344                                         if (0 != (rt = rtget(RIP_DEFAULT, 0))) {
 345                                             j = (rt->rt_metric
 346                                                  +aifp->int_metric
 347                                                  +aifp->int_adj_outmetric
 348                                                  +1);
 349                                             if (i > j)
 350                                                 i = j;
 351                                         }
 352                                         v12buf.n->n_metric = htonl(i);
 353                                         v12buf.n++;
 354                                         break;
 355                                 }
 356
 357                                 /* Respond with RIPv1 instead of RIPv2 if
 358                                  * that is what we are broadcasting on the
 359                                  * interface to keep the remote router from
 360                                  * getting the wrong initial idea of the
 361                                  * routes we send.
 362                                  */
 363                                 supply(from, aifp, OUT_UNICAST, 0,
 364                                        (aifp->int_state & IS_NO_RIPV1_OUT)
 365                                        ? RIPv2 : RIPv1,
 366                                        ap != 0);
 367                                 return;
 368                         }
 369
 370                         /* Ignore authentication */
 371                         if (n->n_family == RIP_AF_AUTH)
 372                                 continue;
 373
 374                         if (n->n_family != RIP_AF_INET) {
 375                                 msglim(&bad_router, FROM_NADDR,
 376                                        "request from %s for unsupported"
 377                                        " (af %d) %s",
 378                                        naddr_ntoa(FROM_NADDR),
 379                                        ntohs(n->n_family),
 380                                        naddr_ntoa(n->n_dst));
 381                                 return;
 382                         }
 383
 384                         /* We are being asked about a specific destination.
 385                          */
 386                         dst = n->n_dst;
 387                         if (!check_dst(dst)) {
 388                                 msglim(&bad_router, FROM_NADDR,
 389                                        "bad queried destination %s from %s",
 390                                        naddr_ntoa(dst),
 391                                        naddr_ntoa(FROM_NADDR));
 392                                 return;
 393                         }
 394
 395                         /* decide what mask was intended */
 396                         if (rip->rip_vers == RIPv1
 397                             || 0 == (mask = ntohl(n->n_mask))
 398                             || 0 != (ntohl(dst) & ~mask))
 399                                 mask = ripv1_mask_host(dst, aifp);
 400
 401                         /* try to find the answer */
 402                         rt = rtget(dst, mask);
 403                         if (!rt && dst != RIP_DEFAULT)
 404                                 rt = rtfind(n->n_dst);
 405
 406                         if (v12buf.buf->rip_vers != RIPv1)
 407                                 v12buf.n->n_mask = mask;
 408                         if (rt == 0) {
 409                                 /* we do not have the answer */
 410                                 v12buf.n->n_metric = HOPCNT_INFINITY;
 411                         } else {
 412                                 /* we have the answer, so compute the
 413                                  * right metric and next hop.
 414                                  */
 415                                 v12buf.n->n_family = RIP_AF_INET;
 416                                 v12buf.n->n_dst = dst;
 417                                 j = rt->rt_metric+1;
 418                                 if (!aifp)
 419                                         ++j;
 420                                 else
 421                                         j += (aifp->int_metric
 422                                               + aifp->int_adj_outmetric);
 423                                 if (j < HOPCNT_INFINITY)
 424                                         v12buf.n->n_metric = j;
 425                                 else
 426                                         v12buf.n->n_metric = HOPCNT_INFINITY;
 427                                 if (v12buf.buf->rip_vers != RIPv1) {
 428                                         v12buf.n->n_tag = rt->rt_tag;
 429                                         v12buf.n->n_mask = mask;
 430                                         if (aifp != 0
 431                                             && on_net(rt->rt_gate,
 432                                                       aifp->int_net,
 433                                                       aifp->int_mask)
 434                                             && rt->rt_gate != aifp->int_addr)
 435                                             v12buf.n->n_nhop = rt->rt_gate;
 436                                 }
 437                         }
 438                         v12buf.n->n_metric = htonl(v12buf.n->n_metric);
 439
 440                         /* Stop paying attention if we fill the output buffer.
 441                          */
 442                         if (++v12buf.n >= v12buf.lim)
 443                                 break;
 444                 } while (++n < lim);
 445
 446                 /* Send the answer about specific routes.
 447                  */
 448                 if (ap != 0 && ap->type == RIP_AUTH_MD5)
 449                         end_md5_auth(&v12buf, ap);
 450
 451                 if (from->sin_port != htons(RIP_PORT)) {
 452                         /* query */
 453                         (void)output(OUT_QUERY, from, aifp,
 454                                      v12buf.buf,
 455                                      ((char *)v12buf.n - (char*)v12buf.buf));
 456                 } else if (supplier) {
 457                         (void)output(OUT_UNICAST, from, aifp,
 458                                      v12buf.buf,
 459                                      ((char *)v12buf.n - (char*)v12buf.buf));
 460                 } else {
 461                         /* Only answer a router if we are a supplier
 462                          * to keep an unwary host that is just starting
 463                          * from picking us an a router.
 464                          */
 465                         ;
 466                 }
 467                 return;
 468
 469         case RIPCMD_TRACEON:
 470         case RIPCMD_TRACEOFF:
 471                 /* Notice that trace messages are turned off for all possible
 472                  * abuse if _PATH_TRACE is undefined in pathnames.h.
 473                  * Notice also that because of the way the trace file is
 474                  * handled in trace.c, no abuse is plausible even if
 475                  * _PATH_TRACE_ is defined.
 476                  *
 477                  * First verify message came from a privileged port. */
 478                 if (ntohs(from->sin_port) > IPPORT_RESERVED) {
 479                         msglog("trace command from untrusted port on %s",
 480                                naddr_ntoa(FROM_NADDR));
 481                         return;
 482                 }
 483                 if (aifp == 0) {
 484                         msglog("trace command from unknown router %s",
 485                                naddr_ntoa(FROM_NADDR));
 486                         return;
 487                 }
 488                 if (rip->rip_cmd == RIPCMD_TRACEON) {
 489                         rip->rip_tracefile[cc-4] = '\0';
 490                         set_tracefile((char*)rip->rip_tracefile,
 491                                       "trace command: %s\n", 0);
 492                 } else {
 493                         trace_off("tracing turned off by %s",
 494                                   naddr_ntoa(FROM_NADDR));
 495                 }
 496                 return;
 497
 498         case RIPCMD_RESPONSE:
 499                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 500                         msglim(&bad_len, FROM_NADDR,
 501                                "response of bad length (%d) from %s",
 502                                cc, naddr_ntoa(FROM_NADDR));
 503                 }
 504
 505                 /* verify message came from a router */
 506                 if (from->sin_port != ntohs(RIP_PORT)) {
 507                         msglim(&bad_router, FROM_NADDR,
 508                                "    discard RIP response from unknown port"
 509                                " %d on %s",
 510                                ntohs(from->sin_port), naddr_ntoa(FROM_NADDR));
 511                         return;
 512                 }
 513
 514                 if (rip_sock < 0) {
 515                         trace_pkt("    discard response while RIP off");
 516                         return;
 517                 }
 518
 519                 /* Are we talking to ourself or a remote gateway?
 520                  */
 521                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 522                 if (ifp1) {
 523                         if (ifp1->int_state & IS_REMOTE) {
 524                                 /* remote gateway */
 525                                 aifp = ifp1;
 526                                 if (check_remote(aifp)) {
 527                                         aifp->int_act_time = now.tv_sec;
 528                                         (void)if_ok(aifp, "remote ");
 529                                 }
 530                         } else {
 531                                 trace_pkt("    discard our own RIP response");
 532                                 return;
 533                         }
 534                 }
 535
 536                 /* Accept routing packets from routers directly connected
 537                  * via broadcast or point-to-point networks, and from
 538                  * those listed in /etc/gateways.
 539                  */
 540                 if (aifp == 0) {
 541                         msglim(&unk_router, FROM_NADDR,
 542                                "   discard response from %s"
 543                                " via unexpected interface",
 544                                naddr_ntoa(FROM_NADDR));
 545                         return;
 546                 }
 547                 if (IS_RIP_IN_OFF(aifp->int_state)) {
 548                         trace_pkt("    discard RIPv%d response"
 549                                   " via disabled interface %s",
 550                                   rip->rip_vers, aifp->int_name);
 551                         return;
 552                 }
 553
 554                 if (n >= lim) {
 555                         msglim(&bad_len, FROM_NADDR, "empty response from %s",
 556                                naddr_ntoa(FROM_NADDR));
 557                         return;
 558                 }
 559
 560                 if (((aifp->int_state & IS_NO_RIPV1_IN)
 561                      && rip->rip_vers == RIPv1)
 562                     || ((aifp->int_state & IS_NO_RIPV2_IN)
 563                         && rip->rip_vers != RIPv1)) {
 564                         trace_pkt("    discard RIPv%d response",
 565                                   rip->rip_vers);
 566                         return;
 567                 }
 568
 569                 /* Ignore routes via dead interface.
 570                  */
 571                 if (aifp->int_state & IS_BROKE) {
 572                         trace_pkt("discard response via broken interface %s",
 573                                   aifp->int_name);
 574                         return;
 575                 }
 576
 577                 /* If the interface cares, ignore bad routers.
 578                  * Trace but do not log this problem, because where it
 579                  * happens, it happens frequently.
 580                  */
 581                 if (aifp->int_state & IS_DISTRUST) {
 582                         tg = tgates;
 583                         while (tg->tgate_addr != FROM_NADDR) {
 584                                 tg = tg->tgate_next;
 585                                 if (tg == 0) {
 586                                         trace_pkt("    discard RIP response"
 587                                                   " from untrusted router %s",
 588                                                   naddr_ntoa(FROM_NADDR));
 589                                         return;
 590                                 }
 591                         }
 592                 }
 593
 594                 /* Authenticate the packet if we have a secret.
 595                  * If we do not have any secrets, ignore the error in
 596                  * RFC 1723 and accept it regardless.
 597                  */
 598                 if (aifp->int_auth[0].type != RIP_AUTH_NONE
 599                     && rip->rip_vers != RIPv1
 600                     && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 601                         return;
 602
 603                 do {
 604                         if (n->n_family == RIP_AF_AUTH)
 605                                 continue;
 606
 607                         n->n_metric = ntohl(n->n_metric);
 608                         dst = n->n_dst;
 609                         if (n->n_family != RIP_AF_INET
 610                             && (n->n_family != RIP_AF_UNSPEC
 611                                 || dst != RIP_DEFAULT)) {
 612                                 msglim(&bad_router, FROM_NADDR,
 613                                        "route from %s to unsupported"
 614                                        " address family=%d destination=%s",
 615                                        naddr_ntoa(FROM_NADDR),
 616                                        n->n_family,
 617                                        naddr_ntoa(dst));
 618                                 continue;
 619                         }
 620                         if (!check_dst(dst)) {
 621                                 msglim(&bad_router, FROM_NADDR,
 622                                        "bad destination %s from %s",
 623                                        naddr_ntoa(dst),
 624                                        naddr_ntoa(FROM_NADDR));
 625                                 return;
 626                         }
 627                         if (n->n_metric == 0
 628                             || n->n_metric > HOPCNT_INFINITY) {
 629                                 msglim(&bad_router, FROM_NADDR,
 630                                        "bad metric %d from %s"
 631                                        " for destination %s",
 632                                        n->n_metric,
 633                                        naddr_ntoa(FROM_NADDR),
 634                                        naddr_ntoa(dst));
 635                                 return;
 636                         }
 637
 638                         /* Notice the next-hop.
 639                          */
 640                         gate = FROM_NADDR;
 641                         if (n->n_nhop != 0) {
 642                                 if (rip->rip_vers == RIPv1) {
 643                                         n->n_nhop = 0;
 644                                 } else {
 645                                     /* Use it only if it is valid. */
 646                                     if (on_net(n->n_nhop,
 647                                                aifp->int_net, aifp->int_mask)
 648                                         && check_dst(n->n_nhop)) {
 649                                             gate = n->n_nhop;
 650                                     } else {
 651                                             msglim(&bad_nhop, FROM_NADDR,
 652                                                    "router %s to %s"
 653                                                    " has bad next hop %s",
 654                                                    naddr_ntoa(FROM_NADDR),
 655                                                    naddr_ntoa(dst),
 656                                                    naddr_ntoa(n->n_nhop));
 657                                             n->n_nhop = 0;
 658                                     }
 659                                 }
 660                         }
 661
 662                         if (rip->rip_vers == RIPv1
 663                             || 0 == (mask = ntohl(n->n_mask))) {
 664                                 mask = ripv1_mask_host(dst,aifp);
 665                         } else if ((ntohl(dst) & ~mask) != 0) {
 666                                 msglim(&bad_mask, FROM_NADDR,
 667                                        "router %s sent bad netmask"
 668                                        " %#lx with %s",
 669                                        naddr_ntoa(FROM_NADDR),
 670                                        (u_long)mask,
 671                                        naddr_ntoa(dst));
 672                                 continue;
 673                         }
 674                         if (rip->rip_vers == RIPv1)
 675                                 n->n_tag = 0;
 676
 677                         /* Adjust metric according to incoming interface..
 678                          */
 679                         n->n_metric += (aifp->int_metric
 680                                         + aifp->int_adj_inmetric);
 681                         if (n->n_metric > HOPCNT_INFINITY)
 682                                 n->n_metric = HOPCNT_INFINITY;
 683
 684                         /* Should we trust this route from this router? */
 685                         if (tg && (tn = tg->tgate_nets)->mask != 0) {
 686                                 for (i = 0; i < MAX_TGATE_NETS; i++, tn++) {
 687                                         if (on_net(dst, tn->net, tn->mask)
 688                                             && tn->mask <= mask)
 689                                             break;
 690                                 }
 691                                 if (i >= MAX_TGATE_NETS || tn->mask == 0) {
 692                                         trace_pkt("   ignored unauthorized %s",
 693                                                   addrname(dst,mask,0));
 694                                         continue;
 695                                 }
 696                         }
 697
 698                         /* Recognize and ignore a default route we faked
 699                          * which is being sent back to us by a machine with
 700                          * broken split-horizon.
 701                          * Be a little more paranoid than that, and reject
 702                          * default routes with the same metric we advertised.
 703                          */
 704                         if (aifp->int_d_metric != 0
 705                             && dst == RIP_DEFAULT
 706                             && (int)n->n_metric >= aifp->int_d_metric)
 707                                 continue;
 708
 709                         /* We can receive aggregated RIPv2 routes that must
 710                          * be broken down before they are transmitted by
 711                          * RIPv1 via an interface on a subnet.
 712                          * We might also receive the same routes aggregated
 713                          * via other RIPv2 interfaces.
 714                          * This could cause duplicate routes to be sent on
 715                          * the RIPv1 interfaces.  "Longest matching variable
 716                          * length netmasks" lets RIPv2 listeners understand,
 717                          * but breaking down the aggregated routes for RIPv1
 718                          * listeners can produce duplicate routes.
 719                          *
 720                          * Breaking down aggregated routes here bloats
 721                          * the daemon table, but does not hurt the kernel
 722                          * table, since routes are always aggregated for
 723                          * the kernel.
 724                          *
 725                          * Notice that this does not break down network
 726                          * routes corresponding to subnets.  This is part
 727                          * of the defense against RS_NET_SYN.
 728                          */
 729                         if (have_ripv1_out
 730                             && (((rt = rtget(dst,mask)) == 0
 731                                  || !(rt->rt_state & RS_NET_SYN)))
 732                             && (v1_mask = ripv1_mask_net(dst,0)) > mask) {
 733                                 ddst_h = v1_mask & -v1_mask;
 734                                 i = (v1_mask & ~mask)/ddst_h;
 735                                 if (i >= 511) {
 736                                         /* Punt if we would have to generate
 737                                          * an unreasonable number of routes.
 738                                          */
 739                                         if (TRACECONTENTS)
 740                                             trace_misc("accept %s-->%s as 1"
 741                                                        " instead of %d routes",
 742                                                        addrname(dst,mask,0),
 743                                                        naddr_ntoa(FROM_NADDR),
 744                                                        i+1);
 745                                         i = 0;
 746                                 } else {
 747                                         mask = v1_mask;
 748                                 }
 749                         } else {
 750                                 i = 0;
 751                         }
 752
 753                         new.rts_gate = gate;
 754                         new.rts_router = FROM_NADDR;
 755                         new.rts_metric = n->n_metric;
 756                         new.rts_tag = n->n_tag;
 757                         new.rts_time = now.tv_sec;
 758                         new.rts_ifp = aifp;
 759                         new.rts_de_ag = i;
 760                         j = 0;
 761                         for (;;) {
 762                                 input_route(dst, mask, &new, n);
 763                                 if (++j > i)
 764                                         break;
 765                                 dst = htonl(ntohl(dst) + ddst_h);
 766                         }
 767                 } while (++n < lim);
 768                 break;
 769         }
 770 #undef FROM_NADDR
 771 }
 772
 773
 774 /* Process a single input route.
 775  */
 776 static void
 777 input_route(naddr dst,                  /* network order */
 778             naddr mask,
 779             struct rt_spare *new,
 780             struct netinfo *n)
 781 {
 782         int i;
 783         struct rt_entry *rt;
 784         struct rt_spare *rts, *rts0;
 785         struct interface *ifp1;
 786
 787
 788         /* See if the other guy is telling us to send our packets to him.
 789          * Sometimes network routes arrive over a point-to-point link for
 790          * the network containing the address(es) of the link.
 791          *
 792          * If our interface is broken, switch to using the other guy.
 793          */
 794         ifp1 = ifwithaddr(dst, 1, 1);
 795         if (ifp1 != 0
 796             && (!(ifp1->int_state & IS_BROKE)
 797                 || (ifp1->int_state & IS_PASSIVE)))
 798                 return;
 799
 800         /* Look for the route in our table.
 801          */
 802         rt = rtget(dst, mask);
 803
 804         /* Consider adding the route if we do not already have it.
 805          */
 806         if (rt == 0) {
 807                 /* Ignore unknown routes being poisoned.
 808                  */
 809                 if (new->rts_metric == HOPCNT_INFINITY)
 810                         return;
 811
 812                 /* Ignore the route if it points to us */
 813                 if (n->n_nhop != 0
 814                     && 0 != ifwithaddr(n->n_nhop, 1, 0))
 815                         return;
 816
 817                 /* If something has not gone crazy and tried to fill
 818                  * our memory, accept the new route.
 819                  */
 820                 if (total_routes < MAX_ROUTES)
 821                         rtadd(dst, mask, 0, new);
 822                 return;
 823         }
 824
 825         /* We already know about the route.  Consider this update.
 826          *
 827          * If (rt->rt_state & RS_NET_SYN), then this route
 828          * is the same as a network route we have inferred
 829          * for subnets we know, in order to tell RIPv1 routers
 830          * about the subnets.
 831          *
 832          * It is impossible to tell if the route is coming
 833          * from a distant RIPv2 router with the standard
 834          * netmask because that router knows about the entire
 835          * network, or if it is a round-about echo of a
 836          * synthetic, RIPv1 network route of our own.
 837          * The worst is that both kinds of routes might be
 838          * received, and the bad one might have the smaller
 839          * metric.  Partly solve this problem by never
 840          * aggregating into such a route.  Also keep it
 841          * around as long as the interface exists.
 842          */
 843
 844         rts0 = rt->rt_spares;
 845         for (rts = rts0, i = NUM_SPARES; i != 0; i--, rts++) {
 846                 if (rts->rts_router == new->rts_router)
 847                         break;
 848                 /* Note the worst slot to reuse,
 849                  * other than the current slot.
 850                  */
 851                 if (rts0 == rt->rt_spares
 852                     || BETTER_LINK(rt, rts0, rts))
 853                         rts0 = rts;
 854         }
 855         if (i != 0) {
 856                 /* Found a route from the router already in the table.
 857                  */
 858
 859                 /* If the new route is a route broken down from an
 860                  * aggregated route, and if the previous route is either
 861                  * not a broken down route or was broken down from a finer
 862                  * netmask, and if the previous route is current,
 863                  * then forget this one.
 864                  */
 865                 if (new->rts_de_ag > rts->rts_de_ag
 866                     && now_stale <= rts->rts_time)
 867                         return;
 868
 869                 /* Keep poisoned routes around only long enough to pass
 870                  * the poison on.  Use a new timestamp for good routes.
 871                  */
 872                 if (rts->rts_metric == HOPCNT_INFINITY
 873                     && new->rts_metric == HOPCNT_INFINITY)
 874                         new->rts_time = rts->rts_time;
 875
 876                 /* If this is an update for the router we currently prefer,
 877                  * then note it.
 878                  */
 879                 if (i == NUM_SPARES) {
 880                         rtchange(rt, rt->rt_state, new, 0);
 881                         /* If the route got worse, check for something better.
 882                          */
 883                         if (new->rts_metric > rts->rts_metric)
 884                                 rtswitch(rt, 0);
 885                         return;
 886                 }
 887
 888                 /* This is an update for a spare route.
 889                  * Finished if the route is unchanged.
 890                  */
 891                 if (rts->rts_gate == new->rts_gate
 892                     && rts->rts_metric == new->rts_metric
 893                     && rts->rts_tag == new->rts_tag) {
 894                         trace_upslot(rt, rts, new);
 895                         *rts = *new;
 896                         return;
 897                 }
 898                 /* Forget it if it has gone bad.
 899                  */
 900                 if (new->rts_metric == HOPCNT_INFINITY) {
 901                         rts_delete(rt, rts);
 902                         return;
 903                 }
 904
 905         } else {
 906                 /* The update is for a route we know about,
 907                  * but not from a familiar router.
 908                  *
 909                  * Ignore the route if it points to us.
 910                  */
 911                 if (n->n_nhop != 0
 912                     && 0 != ifwithaddr(n->n_nhop, 1, 0))
 913                         return;
 914
 915                 /* the loop above set rts0=worst spare */
 916                 rts = rts0;
 917
 918                 /* Save the route as a spare only if it has
 919                  * a better metric than our worst spare.
 920                  * This also ignores poisoned routes (those
 921                  * received with metric HOPCNT_INFINITY).
 922                  */
 923                 if (new->rts_metric >= rts->rts_metric)
 924                         return;
 925         }
 926
 927         trace_upslot(rt, rts, new);
 928         *rts = *new;
 929
 930         /* try to switch to a better route */
 931         rtswitch(rt, rts);
 932 }
 933
 934
 935 static int                              /* 0 if bad */
 936 ck_passwd(struct interface *aifp,
 937           struct rip *rip,
 938           void *lim,
 939           naddr from,
 940           struct msg_limit *use_authp)
 941 {
 942 #       define NA (rip->rip_auths)
 943         struct netauth *na2;
 944         struct auth *ap;
 945         MD5_CTX md5_ctx;
 946         u_char hash[RIP_AUTH_PW_LEN];
 947         int i, len;
 948
 949         assert(aifp != NULL);
 950         if ((void *)NA >= lim || NA->a_family != RIP_AF_AUTH) {
 951                 msglim(use_authp, from, "missing password from %s",
 952                        naddr_ntoa(from));
 953                 return 0;
 954         }
 955
 956         /* accept any current (+/- 24 hours) password
 957          */
 958         for (ap = aifp->int_auth, i = 0; i < MAX_AUTH_KEYS; i++, ap++) {
 959                 if (ap->type != NA->a_type
 960                     || (u_long)ap->start > (u_long)clk.tv_sec+DAY
 961                     || (u_long)ap->end+DAY < (u_long)clk.tv_sec)
 962                         continue;
 963
 964                 if (NA->a_type == RIP_AUTH_PW) {
 965                         if (!memcmp(NA->au.au_pw, ap->key, RIP_AUTH_PW_LEN))
 966                                 return 1;
 967
 968                 } else {
 969                         /* accept MD5 secret with the right key ID
 970                          */
 971                         if (NA->au.a_md5.md5_keyid != ap->keyid)
 972                                 continue;
 973
 974                         len = ntohs(NA->au.a_md5.md5_pkt_len);
 975                         if ((len-sizeof(*rip)) % sizeof(*NA) != 0
 976                             || len != (char *)lim-(char*)rip-(int)sizeof(*NA)) {
 977                                 msglim(use_authp, from,
 978                                        "wrong MD5 RIPv2 packet length of %d"
 979                                        " instead of %d from %s",
 980                                        len, (int)((char *)lim-(char *)rip
 981                                                   -sizeof(*NA)),
 982                                        naddr_ntoa(from));
 983                                 return 0;
 984                         }
 985                         na2 = (struct netauth *)((char *)rip+len);
 986
 987                         /* Given a good hash value, these are not security
 988                          * problems so be generous and accept the routes,
 989                          * after complaining.
 990                          */
 991                         if (TRACEPACKETS) {
 992                                 if (NA->au.a_md5.md5_auth_len
 993                                     != RIP_AUTH_MD5_HASH_LEN)
 994                                         msglim(use_authp, from,
 995                                                "unknown MD5 RIPv2 auth len %#x"
 996                                                " instead of %#x from %s",
 997                                                NA->au.a_md5.md5_auth_len,
 998                                                (unsigned)RIP_AUTH_MD5_HASH_LEN,
 999                                                naddr_ntoa(from));
1000                                 if (na2->a_family != RIP_AF_AUTH)
1001                                         msglim(use_authp, from,
1002                                                "unknown MD5 RIPv2 family %#x"
1003                                                " instead of %#x from %s",
1004                                                na2->a_family, RIP_AF_AUTH,
1005                                                naddr_ntoa(from));
1006                                 if (na2->a_type != ntohs(1))
1007                                         msglim(use_authp, from,
1008                                                "MD5 RIPv2 hash has %#x"
1009                                                " instead of %#x from %s",
1010                                                na2->a_type, ntohs(1),
1011                                                naddr_ntoa(from));
1012                         }
1013
1014                         MD5Init(&md5_ctx);
1015                         MD5Update(&md5_ctx, (u_char *)rip,
1016                                   len + RIP_AUTH_MD5_HASH_XTRA);
1017                         MD5Update(&md5_ctx, ap->key, RIP_AUTH_MD5_KEY_LEN);
1018                         MD5Final(hash, &md5_ctx);
1019                         if (!memcmp(hash, na2->au.au_pw, sizeof(hash)))
1020                                 return 1;
1021                 }
1022         }
1023
1024         msglim(use_authp, from, "bad password from %s",
1025                naddr_ntoa(from));
1026         return 0;
1027 #undef NA
1028 }