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  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgment:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * $FreeBSD: src/sbin/routed/input.c,v 1.7.2.1 2001/08/01 09:01:45 obrien Exp $
  34  * $DragonFly: src/sbin/routed/input.c,v 1.4 2004/12/18 21:43:40 swildner Exp $
  35  */
  36
  37 #include "defs.h"
  38
  39 #if !defined(sgi) && !defined(__NetBSD__)
  40 static char sccsid[] __attribute__((unused)) = "@(#)input.c     8.1 (Berkeley) 6/5/93";
  41 #elif defined(__NetBSD__)
  42 #include <sys/cdefs.h>
  43 __RCSID("$NetBSD$");
  44 #endif
  45
  46 static void input(struct sockaddr_in *, struct interface *, struct interface *,
  47                   struct rip *, int);
  48 static void input_route(naddr, naddr, struct rt_spare *, struct netinfo *);
  49 static int ck_passwd(struct interface *, struct rip *, void *,
  50                      naddr, struct msg_limit *);
  51
  52
  53 /* process RIP input
  54  */
  55 void
  56 read_rip(int sock,
  57          struct interface *sifp)
  58 {
  59         struct sockaddr_in from;
  60         struct interface *aifp;
  61         int fromlen, cc;
  62 #ifdef USE_PASSIFNAME
  63         static struct msg_limit  bad_name;
  64         struct {
  65                 char    ifname[IFNAMSIZ];
  66                 union pkt_buf pbuf;
  67         } inbuf;
  68 #else
  69         struct {
  70                 union pkt_buf pbuf;
  71         } inbuf;
  72 #endif
  73
  74
  75         for (;;) {
  76                 fromlen = sizeof(from);
  77                 cc = recvfrom(sock, &inbuf, sizeof(inbuf), 0,
  78                               (struct sockaddr*)&from, &fromlen);
  79                 if (cc <= 0) {
  80                         if (cc < 0 && errno != EWOULDBLOCK)
  81                                 LOGERR("recvfrom(rip)");
  82                         break;
  83                 }
  84                 if (fromlen != sizeof(struct sockaddr_in))
  85                         logbad(1,"impossible recvfrom(rip) fromlen=%d",
  86                                fromlen);
  87
  88                 /* aifp is the "authenticated" interface via which the packet
  89                  *      arrived.  In fact, it is only the interface on which
  90                  *      the packet should have arrived based on is source
  91                  *      address.
  92                  * sifp is interface associated with the socket through which
  93                  *      the packet was received.
  94                  */
  95 #ifdef USE_PASSIFNAME
  96                 if ((cc -= sizeof(inbuf.ifname)) < 0)
  97                         logbad(0,"missing USE_PASSIFNAME; only %d bytes",
  98                                cc+sizeof(inbuf.ifname));
  99
 100                 /* check the remote interfaces first */
 101                 for (aifp = remote_if; aifp; aifp = aifp->int_rlink) {
 102                         if (aifp->int_addr == from.sin_addr.s_addr)
 103                                 break;
 104                 }
 105                 if (aifp == 0) {
 106                         aifp = ifwithname(inbuf.ifname, 0);
 107                         if (aifp == 0) {
 108                                 msglim(&bad_name, from.sin_addr.s_addr,
 109                                        "impossible interface name %.*s",
 110                                        IFNAMSIZ, inbuf.ifname);
 111                         } else if (((aifp->int_if_flags & IFF_POINTOPOINT)
 112                                     && aifp->int_dstaddr!=from.sin_addr.s_addr)
 113                                    || (!(aifp->int_if_flags & IFF_POINTOPOINT)
 114                                        && !on_net(from.sin_addr.s_addr,
 115                                                   aifp->int_net,
 116                                                   aifp->int_mask))) {
 117                                 /* If it came via the wrong interface, do not
 118                                  * trust it.
 119                                  */
 120                                 aifp = 0;
 121                         }
 122                 }
 123 #else
 124                 aifp = iflookup(from.sin_addr.s_addr);
 125 #endif
 126                 if (sifp == 0)
 127                         sifp = aifp;
 128
 129                 input(&from, sifp, aifp, &inbuf.pbuf.rip, cc);
 130         }
 131 }
 132
 133
 134 /* Process a RIP packet
 135  */
 136 static void
 137 input(struct sockaddr_in *from,         /* received from this IP address */
 138       struct interface *sifp,           /* interface of incoming socket */
 139       struct interface *aifp,           /* "authenticated" interface */
 140       struct rip *rip,
 141       int cc)
 142 {
 143 #       define FROM_NADDR from->sin_addr.s_addr
 144         static struct msg_limit use_auth, bad_len, bad_mask;
 145         static struct msg_limit unk_router, bad_router, bad_nhop;
 146
 147         struct rt_entry *rt;
 148         struct rt_spare new;
 149         struct netinfo *n, *lim;
 150         struct interface *ifp1;
 151         naddr gate, mask, v1_mask, dst, ddst_h = 0;
 152         struct auth *ap;
 153         struct tgate *tg = 0;
 154         struct tgate_net *tn;
 155         int i, j;
 156
 157         /* Notice when we hear from a remote gateway
 158          */
 159         if (aifp != 0
 160             && (aifp->int_state & IS_REMOTE))
 161                 aifp->int_act_time = now.tv_sec;
 162
 163         trace_rip("Recv", "from", from, sifp, rip, cc);
 164
 165         if (rip->rip_vers == 0) {
 166                 msglim(&bad_router, FROM_NADDR,
 167                        "RIP version 0, cmd %d, packet received from %s",
 168                        rip->rip_cmd, naddr_ntoa(FROM_NADDR));
 169                 return;
 170         } else if (rip->rip_vers > RIPv2) {
 171                 rip->rip_vers = RIPv2;
 172         }
 173         if (cc > (int)OVER_MAXPACKETSIZE) {
 174                 msglim(&bad_router, FROM_NADDR,
 175                        "packet at least %d bytes too long received from %s",
 176                        cc-MAXPACKETSIZE, naddr_ntoa(FROM_NADDR));
 177                 return;
 178         }
 179
 180         n = rip->rip_nets;
 181         lim = (struct netinfo *)((char*)rip + cc);
 182
 183         /* Notice authentication.
 184          * As required by section 4.2 in RFC 1723, discard authenticated
 185          * RIPv2 messages, but only if configured for that silliness.
 186          *
 187          * RIPv2 authentication is lame.  Why authenticate queries?
 188          * Why should a RIPv2 implementation with authentication disabled
 189          * not be able to listen to RIPv2 packets with authentication, while
 190          * RIPv1 systems will listen?  Crazy!
 191          */
 192         if (!auth_ok
 193             && rip->rip_vers == RIPv2
 194             && n < lim && n->n_family == RIP_AF_AUTH) {
 195                 msglim(&use_auth, FROM_NADDR,
 196                        "RIPv2 message with authentication from %s discarded",
 197                        naddr_ntoa(FROM_NADDR));
 198                 return;
 199         }
 200
 201         switch (rip->rip_cmd) {
 202         case RIPCMD_REQUEST:
 203                 /* For mere requests, be a little sloppy about the source
 204                  */
 205                 if (aifp == 0)
 206                         aifp = sifp;
 207
 208                 /* Are we talking to ourself or a remote gateway?
 209                  */
 210                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 211                 if (ifp1) {
 212                         if (ifp1->int_state & IS_REMOTE) {
 213                                 /* remote gateway */
 214                                 aifp = ifp1;
 215                                 if (check_remote(aifp)) {
 216                                         aifp->int_act_time = now.tv_sec;
 217                                         if_ok(aifp, "remote ");
 218                                 }
 219                         } else if (from->sin_port == htons(RIP_PORT)) {
 220                                 trace_pkt("    discard our own RIP request");
 221                                 return;
 222                         }
 223                 }
 224
 225                 /* did the request come from a router?
 226                  */
 227                 if (from->sin_port == htons(RIP_PORT)) {
 228                         /* yes, ignore the request if RIP is off so that
 229                          * the router does not depend on us.
 230                          */
 231                         if (rip_sock < 0
 232                             || (aifp != 0
 233                                 && IS_RIP_OUT_OFF(aifp->int_state))) {
 234                                 trace_pkt("    discard request while RIP off");
 235                                 return;
 236                         }
 237                 }
 238
 239                 /* According to RFC 1723, we should ignore unauthenticated
 240                  * queries.  That is too silly to bother with.  Sheesh!
 241                  * Are forwarding tables supposed to be secret, when
 242                  * a bad guy can infer them with test traffic?  When RIP
 243                  * is still the most common router-discovery protocol
 244                  * and so hosts need to send queries that will be answered?
 245                  * What about `rtquery`?
 246                  * Maybe on firewalls you'd care, but not enough to
 247                  * give up the diagnostic facilities of remote probing.
 248                  */
 249
 250                 if (n >= lim) {
 251                         msglim(&bad_len, FROM_NADDR, "empty request from %s",
 252                                naddr_ntoa(FROM_NADDR));
 253                         return;
 254                 }
 255                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 256                         msglim(&bad_len, FROM_NADDR,
 257                                "request of bad length (%d) from %s",
 258                                cc, naddr_ntoa(FROM_NADDR));
 259                 }
 260
 261                 if (rip->rip_vers == RIPv2
 262                     && (aifp == 0 || (aifp->int_state & IS_NO_RIPV1_OUT))) {
 263                         v12buf.buf->rip_vers = RIPv2;
 264                         /* If we have a secret but it is a cleartext secret,
 265                          * do not disclose our secret unless the other guy
 266                          * already knows it.
 267                          */
 268                         ap = find_auth(aifp);
 269                         if (ap != 0 && ap->type == RIP_AUTH_PW
 270                             && n->n_family == RIP_AF_AUTH
 271                             && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 272                                 ap = 0;
 273                 } else {
 274                         v12buf.buf->rip_vers = RIPv1;
 275                         ap = 0;
 276                 }
 277                 clr_ws_buf(&v12buf, ap);
 278
 279                 do {
 280                         n->n_metric = ntohl(n->n_metric);
 281
 282                         /* A single entry with family RIP_AF_UNSPEC and
 283                          * metric HOPCNT_INFINITY means "all routes".
 284                          * We respond to routers only if we are acting
 285                          * as a supplier, or to anyone other than a router
 286                          * (i.e. a query).
 287                          */
 288                         if (n->n_family == RIP_AF_UNSPEC
 289                             && n->n_metric == HOPCNT_INFINITY) {
 290                                 /* Answer a query from a utility program
 291                                  * with all we know.
 292                                  */
 293                                 if (from->sin_port != htons(RIP_PORT)) {
 294                                         supply(from, aifp, OUT_QUERY, 0,
 295                                                rip->rip_vers, ap != 0);
 296                                         return;
 297                                 }
 298
 299                                 /* A router trying to prime its tables.
 300                                  * Filter the answer in the about same way
 301                                  * broadcasts are filtered.
 302                                  *
 303                                  * Only answer a router if we are a supplier
 304                                  * to keep an unwary host that is just starting
 305                                  * from picking us as a router.
 306                                  */
 307                                 if (aifp == 0) {
 308                                         trace_pkt("ignore distant router");
 309                                         return;
 310                                 }
 311                                 if (!supplier
 312                                     || IS_RIP_OFF(aifp->int_state)) {
 313                                         trace_pkt("ignore; not supplying");
 314                                         return;
 315                                 }
 316
 317                                 /* Do not answer a RIPv1 router if
 318                                  * we are sending RIPv2.  But do offer
 319                                  * poor man's router discovery.
 320                                  */
 321                                 if ((aifp->int_state & IS_NO_RIPV1_OUT)
 322                                     && rip->rip_vers == RIPv1) {
 323                                         if (!(aifp->int_state & IS_PM_RDISC)) {
 324                                             trace_pkt("ignore; sending RIPv2");
 325                                             return;
 326                                         }
 327
 328                                         v12buf.n->n_family = RIP_AF_INET;
 329                                         v12buf.n->n_dst = RIP_DEFAULT;
 330                                         i = aifp->int_d_metric;
 331                                         if (0 != (rt = rtget(RIP_DEFAULT, 0)))
 332                                             i = MIN(i, (rt->rt_metric
 333                                                         +aifp->int_metric+1));
 334                                         v12buf.n->n_metric = htonl(i);
 335                                         v12buf.n++;
 336                                         break;
 337                                 }
 338
 339                                 /* Respond with RIPv1 instead of RIPv2 if
 340                                  * that is what we are broadcasting on the
 341                                  * interface to keep the remote router from
 342                                  * getting the wrong initial idea of the
 343                                  * routes we send.
 344                                  */
 345                                 supply(from, aifp, OUT_UNICAST, 0,
 346                                        (aifp->int_state & IS_NO_RIPV1_OUT)
 347                                        ? RIPv2 : RIPv1,
 348                                        ap != 0);
 349                                 return;
 350                         }
 351
 352                         /* Ignore authentication */
 353                         if (n->n_family == RIP_AF_AUTH)
 354                                 continue;
 355
 356                         if (n->n_family != RIP_AF_INET) {
 357                                 msglim(&bad_router, FROM_NADDR,
 358                                        "request from %s for unsupported"
 359                                        " (af %d) %s",
 360                                        naddr_ntoa(FROM_NADDR),
 361                                        ntohs(n->n_family),
 362                                        naddr_ntoa(n->n_dst));
 363                                 return;
 364                         }
 365
 366                         /* We are being asked about a specific destination.
 367                          */
 368                         dst = n->n_dst;
 369                         if (!check_dst(dst)) {
 370                                 msglim(&bad_router, FROM_NADDR,
 371                                        "bad queried destination %s from %s",
 372                                        naddr_ntoa(dst),
 373                                        naddr_ntoa(FROM_NADDR));
 374                                 return;
 375                         }
 376
 377                         /* decide what mask was intended */
 378                         if (rip->rip_vers == RIPv1
 379                             || 0 == (mask = ntohl(n->n_mask))
 380                             || 0 != (ntohl(dst) & ~mask))
 381                                 mask = ripv1_mask_host(dst, aifp);
 382
 383                         /* try to find the answer */
 384                         rt = rtget(dst, mask);
 385                         if (!rt && dst != RIP_DEFAULT)
 386                                 rt = rtfind(n->n_dst);
 387
 388                         if (v12buf.buf->rip_vers != RIPv1)
 389                                 v12buf.n->n_mask = mask;
 390                         if (rt == 0) {
 391                                 /* we do not have the answer */
 392                                 v12buf.n->n_metric = HOPCNT_INFINITY;
 393                         } else {
 394                                 /* we have the answer, so compute the
 395                                  * right metric and next hop.
 396                                  */
 397                                 v12buf.n->n_family = RIP_AF_INET;
 398                                 v12buf.n->n_dst = dst;
 399                                 v12buf.n->n_metric = (rt->rt_metric+1
 400                                                       + ((aifp!=0)
 401                                                           ? aifp->int_metric
 402                                                           : 1));
 403                                 if (v12buf.n->n_metric > HOPCNT_INFINITY)
 404                                         v12buf.n->n_metric = HOPCNT_INFINITY;
 405                                 if (v12buf.buf->rip_vers != RIPv1) {
 406                                         v12buf.n->n_tag = rt->rt_tag;
 407                                         v12buf.n->n_mask = mask;
 408                                         if (aifp != 0
 409                                             && on_net(rt->rt_gate,
 410                                                       aifp->int_net,
 411                                                       aifp->int_mask)
 412                                             && rt->rt_gate != aifp->int_addr)
 413                                             v12buf.n->n_nhop = rt->rt_gate;
 414                                 }
 415                         }
 416                         v12buf.n->n_metric = htonl(v12buf.n->n_metric);
 417
 418                         /* Stop paying attention if we fill the output buffer.
 419                          */
 420                         if (++v12buf.n >= v12buf.lim)
 421                                 break;
 422                 } while (++n < lim);
 423
 424                 /* Send the answer about specific routes.
 425                  */
 426                 if (ap != 0 && ap->type == RIP_AUTH_MD5)
 427                         end_md5_auth(&v12buf, ap);
 428
 429                 if (from->sin_port != htons(RIP_PORT)) {
 430                         /* query */
 431                         output(OUT_QUERY, from, aifp,
 432                                v12buf.buf,
 433                                ((char *)v12buf.n - (char*)v12buf.buf));
 434                 } else if (supplier) {
 435                         output(OUT_UNICAST, from, aifp,
 436                                v12buf.buf,
 437                                ((char *)v12buf.n - (char*)v12buf.buf));
 438                 } else {
 439                         /* Only answer a router if we are a supplier
 440                          * to keep an unwary host that is just starting
 441                          * from picking us an a router.
 442                          */
 443                         ;
 444                 }
 445                 return;
 446
 447         case RIPCMD_TRACEON:
 448         case RIPCMD_TRACEOFF:
 449                 /* Notice that trace messages are turned off for all possible
 450                  * abuse if _PATH_TRACE is undefined in pathnames.h.
 451                  * Notice also that because of the way the trace file is
 452                  * handled in trace.c, no abuse is plausible even if
 453                  * _PATH_TRACE_ is defined.
 454                  *
 455                  * First verify message came from a privileged port. */
 456                 if (ntohs(from->sin_port) > IPPORT_RESERVED) {
 457                         msglog("trace command from untrusted port on %s",
 458                                naddr_ntoa(FROM_NADDR));
 459                         return;
 460                 }
 461                 if (aifp == 0) {
 462                         msglog("trace command from unknown router %s",
 463                                naddr_ntoa(FROM_NADDR));
 464                         return;
 465                 }
 466                 if (rip->rip_cmd == RIPCMD_TRACEON) {
 467                         rip->rip_tracefile[cc-4] = '\0';
 468                         set_tracefile((char*)rip->rip_tracefile,
 469                                       "trace command: %s\n", 0);
 470                 } else {
 471                         trace_off("tracing turned off by %s",
 472                                   naddr_ntoa(FROM_NADDR));
 473                 }
 474                 return;
 475
 476         case RIPCMD_RESPONSE:
 477                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 478                         msglim(&bad_len, FROM_NADDR,
 479                                "response of bad length (%d) from %s",
 480                                cc, naddr_ntoa(FROM_NADDR));
 481                 }
 482
 483                 /* verify message came from a router */
 484                 if (from->sin_port != ntohs(RIP_PORT)) {
 485                         msglim(&bad_router, FROM_NADDR,
 486                                "    discard RIP response from unknown port"
 487                                " %d on host %s", ntohs(from->sin_port),
 488                                 naddr_ntoa(FROM_NADDR));
 489                         return;
 490                 }
 491
 492                 if (rip_sock < 0) {
 493                         trace_pkt("    discard response while RIP off");
 494                         return;
 495                 }
 496
 497                 /* Are we talking to ourself or a remote gateway?
 498                  */
 499                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 500                 if (ifp1) {
 501                         if (ifp1->int_state & IS_REMOTE) {
 502                                 /* remote gateway */
 503                                 aifp = ifp1;
 504                                 if (check_remote(aifp)) {
 505                                         aifp->int_act_time = now.tv_sec;
 506                                         if_ok(aifp, "remote ");
 507                                 }
 508                         } else {
 509                                 trace_pkt("    discard our own RIP response");
 510                                 return;
 511                         }
 512                 }
 513
 514                 /* Accept routing packets from routers directly connected
 515                  * via broadcast or point-to-point networks, and from
 516                  * those listed in /etc/gateways.
 517                  */
 518                 if (aifp == 0) {
 519                         msglim(&unk_router, FROM_NADDR,
 520                                "   discard response from %s"
 521                                " via unexpected interface",
 522                                naddr_ntoa(FROM_NADDR));
 523                         return;
 524                 }
 525                 if (IS_RIP_IN_OFF(aifp->int_state)) {
 526                         trace_pkt("    discard RIPv%d response"
 527                                   " via disabled interface %s",
 528                                   rip->rip_vers, aifp->int_name);
 529                         return;
 530                 }
 531
 532                 if (n >= lim) {
 533                         msglim(&bad_len, FROM_NADDR, "empty response from %s",
 534                                naddr_ntoa(FROM_NADDR));
 535                         return;
 536                 }
 537
 538                 if (((aifp->int_state & IS_NO_RIPV1_IN)
 539                      && rip->rip_vers == RIPv1)
 540                     || ((aifp->int_state & IS_NO_RIPV2_IN)
 541                         && rip->rip_vers != RIPv1)) {
 542                         trace_pkt("    discard RIPv%d response",
 543                                   rip->rip_vers);
 544                         return;
 545                 }
 546
 547                 /* Ignore routes via dead interface.
 548                  */
 549                 if (aifp->int_state & IS_BROKE) {
 550                         trace_pkt("discard response via broken interface %s",
 551                                   aifp->int_name);
 552                         return;
 553                 }
 554
 555                 /* If the interface cares, ignore bad routers.
 556                  * Trace but do not log this problem, because where it
 557                  * happens, it happens frequently.
 558                  */
 559                 if (aifp->int_state & IS_DISTRUST) {
 560                         tg = tgates;
 561                         while (tg->tgate_addr != FROM_NADDR) {
 562                                 tg = tg->tgate_next;
 563                                 if (tg == 0) {
 564                                         trace_pkt("    discard RIP response"
 565                                                   " from untrusted router %s",
 566                                                   naddr_ntoa(FROM_NADDR));
 567                                         return;
 568                                 }
 569                         }
 570                 }
 571
 572                 /* Authenticate the packet if we have a secret.
 573                  * If we do not have any secrets, ignore the error in
 574                  * RFC 1723 and accept it regardless.
 575                  */
 576                 if (aifp->int_auth[0].type != RIP_AUTH_NONE
 577                     && rip->rip_vers != RIPv1
 578                     && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 579                         return;
 580
 581                 do {
 582                         if (n->n_family == RIP_AF_AUTH)
 583                                 continue;
 584
 585                         n->n_metric = ntohl(n->n_metric);
 586                         dst = n->n_dst;
 587                         if (n->n_family != RIP_AF_INET
 588                             && (n->n_family != RIP_AF_UNSPEC
 589                                 || dst != RIP_DEFAULT)) {
 590                                 msglim(&bad_router, FROM_NADDR,
 591                                        "route from %s to unsupported"
 592                                        " address family=%d destination=%s",
 593                                        naddr_ntoa(FROM_NADDR),
 594                                        n->n_family,
 595                                        naddr_ntoa(dst));
 596                                 continue;
 597                         }
 598                         if (!check_dst(dst)) {
 599                                 msglim(&bad_router, FROM_NADDR,
 600                                        "bad destination %s from %s",
 601                                        naddr_ntoa(dst),
 602                                        naddr_ntoa(FROM_NADDR));
 603                                 return;
 604                         }
 605                         if (n->n_metric == 0
 606                             || n->n_metric > HOPCNT_INFINITY) {
 607                                 msglim(&bad_router, FROM_NADDR,
 608                                        "bad metric %d from %s"
 609                                        " for destination %s",
 610                                        n->n_metric,
 611                                        naddr_ntoa(FROM_NADDR),
 612                                        naddr_ntoa(dst));
 613                                 return;
 614                         }
 615
 616                         /* Notice the next-hop.
 617                          */
 618                         gate = FROM_NADDR;
 619                         if (n->n_nhop != 0) {
 620                                 if (rip->rip_vers == RIPv1) {
 621                                         n->n_nhop = 0;
 622                                 } else {
 623                                     /* Use it only if it is valid. */
 624                                     if (on_net(n->n_nhop,
 625                                                aifp->int_net, aifp->int_mask)
 626                                         && check_dst(n->n_nhop)) {
 627                                             gate = n->n_nhop;
 628                                     } else {
 629                                             msglim(&bad_nhop, FROM_NADDR,
 630                                                    "router %s to %s"
 631                                                    " has bad next hop %s",
 632                                                    naddr_ntoa(FROM_NADDR),
 633                                                    naddr_ntoa(dst),
 634                                                    naddr_ntoa(n->n_nhop));
 635                                             n->n_nhop = 0;
 636                                     }
 637                                 }
 638                         }
 639
 640                         if (rip->rip_vers == RIPv1
 641                             || 0 == (mask = ntohl(n->n_mask))) {
 642                                 mask = ripv1_mask_host(dst,aifp);
 643                         } else if ((ntohl(dst) & ~mask) != 0) {
 644                                 msglim(&bad_mask, FROM_NADDR,
 645                                        "router %s sent bad netmask"
 646                                        " %#lx with %s",
 647                                        naddr_ntoa(FROM_NADDR),
 648                                        (u_long)mask,
 649                                        naddr_ntoa(dst));
 650                                 continue;
 651                         }
 652                         if (rip->rip_vers == RIPv1)
 653                                 n->n_tag = 0;
 654
 655                         /* Adjust metric according to incoming interface..
 656                          */
 657                         n->n_metric += aifp->int_metric;
 658                         if (n->n_metric > HOPCNT_INFINITY)
 659                                 n->n_metric = HOPCNT_INFINITY;
 660
 661                         /* Should we trust this route from this router? */
 662                         if (tg && (tn = tg->tgate_nets)->mask != 0) {
 663                                 for (i = 0; i < MAX_TGATE_NETS; i++, tn++) {
 664                                         if (on_net(dst, tn->net, tn->mask)
 665                                             && tn->mask <= mask)
 666                                             break;
 667                                 }
 668                                 if (i >= MAX_TGATE_NETS || tn->mask == 0) {
 669                                         trace_pkt("   ignored unauthorized %s",
 670                                                   addrname(dst,mask,0));
 671                                         continue;
 672                                 }
 673                         }
 674
 675                         /* Recognize and ignore a default route we faked
 676                          * which is being sent back to us by a machine with
 677                          * broken split-horizon.
 678                          * Be a little more paranoid than that, and reject
 679                          * default routes with the same metric we advertised.
 680                          */
 681                         if (aifp->int_d_metric != 0
 682                             && dst == RIP_DEFAULT
 683                             && (int)n->n_metric >= aifp->int_d_metric)
 684                                 continue;
 685
 686                         /* We can receive aggregated RIPv2 routes that must
 687                          * be broken down before they are transmitted by
 688                          * RIPv1 via an interface on a subnet.
 689                          * We might also receive the same routes aggregated
 690                          * via other RIPv2 interfaces.
 691                          * This could cause duplicate routes to be sent on
 692                          * the RIPv1 interfaces.  "Longest matching variable
 693                          * length netmasks" lets RIPv2 listeners understand,
 694                          * but breaking down the aggregated routes for RIPv1
 695                          * listeners can produce duplicate routes.
 696                          *
 697                          * Breaking down aggregated routes here bloats
 698                          * the daemon table, but does not hurt the kernel
 699                          * table, since routes are always aggregated for
 700                          * the kernel.
 701                          *
 702                          * Notice that this does not break down network
 703                          * routes corresponding to subnets.  This is part
 704                          * of the defense against RS_NET_SYN.
 705                          */
 706                         if (have_ripv1_out
 707                             && (((rt = rtget(dst,mask)) == 0
 708                                  || !(rt->rt_state & RS_NET_SYN)))
 709                             && (v1_mask = ripv1_mask_net(dst,0)) > mask) {
 710                                 ddst_h = v1_mask & -v1_mask;
 711                                 i = (v1_mask & ~mask)/ddst_h;
 712                                 if (i >= 511) {
 713                                         /* Punt if we would have to generate
 714                                          * an unreasonable number of routes.
 715                                          */
 716                                         if (TRACECONTENTS)
 717                                             trace_misc("accept %s-->%s as 1"
 718                                                        " instead of %d routes",
 719                                                        addrname(dst,mask,0),
 720                                                        naddr_ntoa(FROM_NADDR),
 721                                                        i+1);
 722                                         i = 0;
 723                                 } else {
 724                                         mask = v1_mask;
 725                                 }
 726                         } else {
 727                                 i = 0;
 728                         }
 729
 730                         new.rts_gate = gate;
 731                         new.rts_router = FROM_NADDR;
 732                         new.rts_metric = n->n_metric;
 733                         new.rts_tag = n->n_tag;
 734                         new.rts_time = now.tv_sec;
 735                         new.rts_ifp = aifp;
 736                         new.rts_de_ag = i;
 737                         j = 0;
 738                         for (;;) {
 739                                 input_route(dst, mask, &new, n);
 740                                 if (++j > i)
 741                                         break;
 742                                 dst = htonl(ntohl(dst) + ddst_h);
 743                         }
 744                 } while (++n < lim);
 745                 break;
 746         }
 747 #undef FROM_NADDR
 748 }
 749
 750
 751 /* Process a single input route.
 752  */
 753 static void
 754 input_route(naddr dst,                  /* network order */
 755             naddr mask,
 756             struct rt_spare *new,
 757             struct netinfo *n)
 758 {
 759         int i;
 760         struct rt_entry *rt;
 761         struct rt_spare *rts, *rts0;
 762         struct interface *ifp1;
 763
 764
 765         /* See if the other guy is telling us to send our packets to him.
 766          * Sometimes network routes arrive over a point-to-point link for
 767          * the network containing the address(es) of the link.
 768          *
 769          * If our interface is broken, switch to using the other guy.
 770          */
 771         ifp1 = ifwithaddr(dst, 1, 1);
 772         if (ifp1 != 0
 773             && (!(ifp1->int_state & IS_BROKE)
 774                 || (ifp1->int_state & IS_PASSIVE)))
 775                 return;
 776
 777         /* Look for the route in our table.
 778          */
 779         rt = rtget(dst, mask);
 780
 781         /* Consider adding the route if we do not already have it.
 782          */
 783         if (rt == 0) {
 784                 /* Ignore unknown routes being poisoned.
 785                  */
 786                 if (new->rts_metric == HOPCNT_INFINITY)
 787                         return;
 788
 789                 /* Ignore the route if it points to us */
 790                 if (n->n_nhop != 0
 791                     && 0 != ifwithaddr(n->n_nhop, 1, 0))
 792                         return;
 793
 794                 /* If something has not gone crazy and tried to fill
 795                  * our memory, accept the new route.
 796                  */
 797                 if (total_routes < MAX_ROUTES)
 798                         rtadd(dst, mask, 0, new);
 799                 return;
 800         }
 801
 802         /* We already know about the route.  Consider this update.
 803          *
 804          * If (rt->rt_state & RS_NET_SYN), then this route
 805          * is the same as a network route we have inferred
 806          * for subnets we know, in order to tell RIPv1 routers
 807          * about the subnets.
 808          *
 809          * It is impossible to tell if the route is coming
 810          * from a distant RIPv2 router with the standard
 811          * netmask because that router knows about the entire
 812          * network, or if it is a round-about echo of a
 813          * synthetic, RIPv1 network route of our own.
 814          * The worst is that both kinds of routes might be
 815          * received, and the bad one might have the smaller
 816          * metric.  Partly solve this problem by never
 817          * aggregating into such a route.  Also keep it
 818          * around as long as the interface exists.
 819          */
 820
 821         rts0 = rt->rt_spares;
 822         for (rts = rts0, i = NUM_SPARES; i != 0; i--, rts++) {
 823                 if (rts->rts_router == new->rts_router)
 824                         break;
 825                 /* Note the worst slot to reuse,
 826                  * other than the current slot.
 827                  */
 828                 if (rts0 == rt->rt_spares
 829                     || BETTER_LINK(rt, rts0, rts))
 830                         rts0 = rts;
 831         }
 832         if (i != 0) {
 833                 /* Found a route from the router already in the table.
 834                  */
 835
 836                 /* If the new route is a route broken down from an
 837                  * aggregated route, and if the previous route is either
 838                  * not a broken down route or was broken down from a finer
 839                  * netmask, and if the previous route is current,
 840                  * then forget this one.
 841                  */
 842                 if (new->rts_de_ag > rts->rts_de_ag
 843                     && now_stale <= rts->rts_time)
 844                         return;
 845
 846                 /* Keep poisoned routes around only long enough to pass
 847                  * the poison on.  Use a new timestamp for good routes.
 848                  */
 849                 if (rts->rts_metric == HOPCNT_INFINITY
 850                     && new->rts_metric == HOPCNT_INFINITY)
 851                         new->rts_time = rts->rts_time;
 852
 853                 /* If this is an update for the router we currently prefer,
 854                  * then note it.
 855                  */
 856                 if (i == NUM_SPARES) {
 857                         rtchange(rt, rt->rt_state, new, 0);
 858                         /* If the route got worse, check for something better.
 859                          */
 860                         if (new->rts_metric > rts->rts_metric)
 861                                 rtswitch(rt, 0);
 862                         return;
 863                 }
 864
 865                 /* This is an update for a spare route.
 866                  * Finished if the route is unchanged.
 867                  */
 868                 if (rts->rts_gate == new->rts_gate
 869                     && rts->rts_metric == new->rts_metric
 870                     && rts->rts_tag == new->rts_tag) {
 871                         trace_upslot(rt, rts, new);
 872                         *rts = *new;
 873                         return;
 874                 }
 875                 /* Forget it if it has gone bad.
 876                  */
 877                 if (new->rts_metric == HOPCNT_INFINITY) {
 878                         rts_delete(rt, rts);
 879                         return;
 880                 }
 881
 882         } else {
 883                 /* The update is for a route we know about,
 884                  * but not from a familiar router.
 885                  *
 886                  * Ignore the route if it points to us.
 887                  */
 888                 if (n->n_nhop != 0
 889                     && 0 != ifwithaddr(n->n_nhop, 1, 0))
 890                         return;
 891
 892                 /* the loop above set rts0=worst spare */
 893                 rts = rts0;
 894
 895                 /* Save the route as a spare only if it has
 896                  * a better metric than our worst spare.
 897                  * This also ignores poisoned routes (those
 898                  * received with metric HOPCNT_INFINITY).
 899                  */
 900                 if (new->rts_metric >= rts->rts_metric)
 901                         return;
 902         }
 903
 904         trace_upslot(rt, rts, new);
 905         *rts = *new;
 906
 907         /* try to switch to a better route */
 908         rtswitch(rt, rts);
 909 }
 910
 911
 912 static int                              /* 0 if bad */
 913 ck_passwd(struct interface *aifp,
 914           struct rip *rip,
 915           void *lim,
 916           naddr from,
 917           struct msg_limit *use_authp)
 918 {
 919 #       define NA (rip->rip_auths)
 920         struct netauth *na2;
 921         struct auth *ap;
 922         MD5_CTX md5_ctx;
 923         u_char hash[RIP_AUTH_PW_LEN];
 924         int i, len;
 925
 926
 927         if ((void *)NA >= lim || NA->a_family != RIP_AF_AUTH) {
 928                 msglim(use_authp, from, "missing password from %s",
 929                        naddr_ntoa(from));
 930                 return 0;
 931         }
 932
 933         /* accept any current (+/- 24 hours) password
 934          */
 935         for (ap = aifp->int_auth, i = 0; i < MAX_AUTH_KEYS; i++, ap++) {
 936                 if (ap->type != NA->a_type
 937                     || (u_long)ap->start > (u_long)clk.tv_sec+DAY
 938                     || (u_long)ap->end+DAY < (u_long)clk.tv_sec)
 939                         continue;
 940
 941                 if (NA->a_type == RIP_AUTH_PW) {
 942                         if (!memcmp(NA->au.au_pw, ap->key, RIP_AUTH_PW_LEN))
 943                                 return 1;
 944
 945                 } else {
 946                         /* accept MD5 secret with the right key ID
 947                          */
 948                         if (NA->au.a_md5.md5_keyid != ap->keyid)
 949                                 continue;
 950
 951                         len = ntohs(NA->au.a_md5.md5_pkt_len);
 952                         if ((len-sizeof(*rip)) % sizeof(*NA) != 0
 953                             || len != (char *)lim-(char*)rip-(int)sizeof(*NA)) {
 954                                 msglim(use_authp, from,
 955                                        "wrong MD5 RIPv2 packet length of %d"
 956                                        " instead of %d from %s",
 957                                        len, (int)((char *)lim-(char *)rip
 958                                                   -sizeof(*NA)),
 959                                        naddr_ntoa(from));
 960                                 return 0;
 961                         }
 962                         na2 = (struct netauth *)((char *)rip+len);
 963
 964                         /* Given a good hash value, these are not security
 965                          * problems so be generous and accept the routes,
 966                          * after complaining.
 967                          */
 968                         if (TRACEPACKETS) {
 969                                 if (NA->au.a_md5.md5_auth_len
 970                                     != RIP_AUTH_MD5_LEN)
 971                                         msglim(use_authp, from,
 972                                                "unknown MD5 RIPv2 auth len %#x"
 973                                                " instead of %#x from %s",
 974                                                NA->au.a_md5.md5_auth_len,
 975                                                RIP_AUTH_MD5_LEN,
 976                                                naddr_ntoa(from));
 977                                 if (na2->a_family != RIP_AF_AUTH)
 978                                         msglim(use_authp, from,
 979                                                "unknown MD5 RIPv2 family %#x"
 980                                                " instead of %#x from %s",
 981                                                na2->a_family, RIP_AF_AUTH,
 982                                                naddr_ntoa(from));
 983                                 if (na2->a_type != ntohs(1))
 984                                         msglim(use_authp, from,
 985                                                "MD5 RIPv2 hash has %#x"
 986                                                " instead of %#x from %s",
 987                                                na2->a_type, ntohs(1),
 988                                                naddr_ntoa(from));
 989                         }
 990
 991                         MD5Init(&md5_ctx);
 992                         MD5Update(&md5_ctx, (u_char *)rip, len);
 993                         MD5Update(&md5_ctx, ap->key, RIP_AUTH_MD5_LEN);
 994                         MD5Final(hash, &md5_ctx);
 995                         if (!memcmp(hash, na2->au.au_pw, sizeof(hash)))
 996                                 return 1;
 997                 }
 998         }
 999
1000         msglim(use_authp, from, "bad password from %s",
1001                naddr_ntoa(from));
1002         return 0;
1003 #undef NA
1004 }