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