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  */
  35
  36 #include "defs.h"
  37
  38 #if !defined(sgi) && !defined(__NetBSD__)
  39 static char sccsid[] __attribute__((unused)) = "@(#)input.c     8.1 (Berkeley) 6/5/93";
  40 #elif defined(__NetBSD__)
  41 #include <sys/cdefs.h>
  42 __RCSID("$NetBSD$");
  43 #endif
  44
  45 static void input(struct sockaddr_in *, struct interface *, struct interface *,
  46                   struct rip *, int);
  47 static void input_route(naddr, naddr, struct rt_spare *, struct netinfo *);
  48 static int ck_passwd(struct interface *, struct rip *, void *,
  49                      naddr, struct msg_limit *);
  50
  51
  52 /* process RIP input
  53  */
  54 void
  55 read_rip(int sock,
  56          struct interface *sifp)
  57 {
  58         struct sockaddr_in from;
  59         struct interface *aifp;
  60         int cc;
  61         socklen_t fromlen;
  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 == NULL) {
 106                         aifp = ifwithname(inbuf.ifname, 0);
 107                         if (aifp == NULL) {
 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 = NULL;
 121                         }
 122                 }
 123 #else
 124                 aifp = iflookup(from.sin_addr.s_addr);
 125 #endif
 126                 if (sifp == NULL)
 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 = NULL;
 154         struct tgate_net *tn;
 155         int i, j;
 156
 157         /* Notice when we hear from a remote gateway
 158          */
 159         if (aifp != NULL
 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 == NULL)
 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 != NULL
 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 == NULL || (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 != NULL && ap->type == RIP_AUTH_PW
 270                             && n->n_family == RIP_AF_AUTH
 271                             && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 272                                 ap = NULL;
 273                 } else {
 274                         v12buf.buf->rip_vers = RIPv1;
 275                         ap = NULL;
 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 (aifp == NULL) {
 294                                         trace_pkt("ignore remote query");
 295                                         return;
 296                                 }
 297                                 if (from->sin_port != htons(RIP_PORT)) {
 298                                         supply(from, aifp, OUT_QUERY, 0,
 299                                                rip->rip_vers, ap != NULL);
 300                                         return;
 301                                 }
 302
 303                                 /* A router trying to prime its tables.
 304                                  * Filter the answer in the about same way
 305                                  * broadcasts are filtered.
 306                                  *
 307                                  * Only answer a router if we are a supplier
 308                                  * to keep an unwary host that is just starting
 309                                  * from picking us as a router.
 310                                  */
 311                                 if (aifp == NULL) {
 312                                         trace_pkt("ignore distant router");
 313                                         return;
 314                                 }
 315                                 if (!supplier
 316                                     || IS_RIP_OFF(aifp->int_state)) {
 317                                         trace_pkt("ignore; not supplying");
 318                                         return;
 319                                 }
 320
 321                                 /* Do not answer a RIPv1 router if
 322                                  * we are sending RIPv2.  But do offer
 323                                  * poor man's router discovery.
 324                                  */
 325                                 if ((aifp->int_state & IS_NO_RIPV1_OUT)
 326                                     && rip->rip_vers == RIPv1) {
 327                                         if (!(aifp->int_state & IS_PM_RDISC)) {
 328                                             trace_pkt("ignore; sending RIPv2");
 329                                             return;
 330                                         }
 331
 332                                         v12buf.n->n_family = RIP_AF_INET;
 333                                         v12buf.n->n_dst = RIP_DEFAULT;
 334                                         i = aifp->int_d_metric;
 335                                         if (NULL != (rt = rtget(RIP_DEFAULT, 0)))
 336                                             i = MIN(i, (rt->rt_metric
 337                                                         +aifp->int_metric+1));
 338                                         v12buf.n->n_metric = htonl(i);
 339                                         v12buf.n++;
 340                                         break;
 341                                 }
 342
 343                                 /* Respond with RIPv1 instead of RIPv2 if
 344                                  * that is what we are broadcasting on the
 345                                  * interface to keep the remote router from
 346                                  * getting the wrong initial idea of the
 347                                  * routes we send.
 348                                  */
 349                                 supply(from, aifp, OUT_UNICAST, 0,
 350                                        (aifp->int_state & IS_NO_RIPV1_OUT)
 351                                        ? RIPv2 : RIPv1,
 352                                        ap != NULL);
 353                                 return;
 354                         }
 355
 356                         /* Ignore authentication */
 357                         if (n->n_family == RIP_AF_AUTH)
 358                                 continue;
 359
 360                         if (n->n_family != RIP_AF_INET) {
 361                                 msglim(&bad_router, FROM_NADDR,
 362                                        "request from %s for unsupported"
 363                                        " (af %d) %s",
 364                                        naddr_ntoa(FROM_NADDR),
 365                                        ntohs(n->n_family),
 366                                        naddr_ntoa(n->n_dst));
 367                                 return;
 368                         }
 369
 370                         /* We are being asked about a specific destination.
 371                          */
 372                         dst = n->n_dst;
 373                         if (!check_dst(dst)) {
 374                                 msglim(&bad_router, FROM_NADDR,
 375                                        "bad queried destination %s from %s",
 376                                        naddr_ntoa(dst),
 377                                        naddr_ntoa(FROM_NADDR));
 378                                 return;
 379                         }
 380
 381                         /* decide what mask was intended */
 382                         if (rip->rip_vers == RIPv1
 383                             || 0 == (mask = ntohl(n->n_mask))
 384                             || 0 != (ntohl(dst) & ~mask))
 385                                 mask = ripv1_mask_host(dst, aifp);
 386
 387                         /* try to find the answer */
 388                         rt = rtget(dst, mask);
 389                         if (!rt && dst != RIP_DEFAULT)
 390                                 rt = rtfind(n->n_dst);
 391
 392                         if (v12buf.buf->rip_vers != RIPv1)
 393                                 v12buf.n->n_mask = mask;
 394                         if (rt == NULL) {
 395                                 /* we do not have the answer */
 396                                 v12buf.n->n_metric = HOPCNT_INFINITY;
 397                         } else {
 398                                 /* we have the answer, so compute the
 399                                  * right metric and next hop.
 400                                  */
 401                                 v12buf.n->n_family = RIP_AF_INET;
 402                                 v12buf.n->n_dst = dst;
 403                                 v12buf.n->n_metric = (rt->rt_metric+1
 404                                                       + ((aifp!=NULL)
 405                                                           ? aifp->int_metric
 406                                                           : 1));
 407                                 if (v12buf.n->n_metric > HOPCNT_INFINITY)
 408                                         v12buf.n->n_metric = HOPCNT_INFINITY;
 409                                 if (v12buf.buf->rip_vers != RIPv1) {
 410                                         v12buf.n->n_tag = rt->rt_tag;
 411                                         v12buf.n->n_mask = mask;
 412                                         if (aifp != NULL
 413                                             && on_net(rt->rt_gate,
 414                                                       aifp->int_net,
 415                                                       aifp->int_mask)
 416                                             && rt->rt_gate != aifp->int_addr)
 417                                             v12buf.n->n_nhop = rt->rt_gate;
 418                                 }
 419                         }
 420                         v12buf.n->n_metric = htonl(v12buf.n->n_metric);
 421
 422                         /* Stop paying attention if we fill the output buffer.
 423                          */
 424                         if (++v12buf.n >= v12buf.lim)
 425                                 break;
 426                 } while (++n < lim);
 427
 428                 /* Send the answer about specific routes.
 429                  */
 430                 if (ap != NULL && ap->type == RIP_AUTH_MD5)
 431                         end_md5_auth(&v12buf, ap);
 432
 433                 if (from->sin_port != htons(RIP_PORT)) {
 434                         /* query */
 435                         output(OUT_QUERY, from, aifp,
 436                                v12buf.buf,
 437                                ((char *)v12buf.n - (char*)v12buf.buf));
 438                 } else if (supplier) {
 439                         output(OUT_UNICAST, from, aifp,
 440                                v12buf.buf,
 441                                ((char *)v12buf.n - (char*)v12buf.buf));
 442                 } else {
 443                         /* Only answer a router if we are a supplier
 444                          * to keep an unwary host that is just starting
 445                          * from picking us an a router.
 446                          */
 447                         ;
 448                 }
 449                 return;
 450
 451         case RIPCMD_TRACEON:
 452         case RIPCMD_TRACEOFF:
 453                 /* Notice that trace messages are turned off for all possible
 454                  * abuse if _PATH_TRACE is undefined in pathnames.h.
 455                  * Notice also that because of the way the trace file is
 456                  * handled in trace.c, no abuse is plausible even if
 457                  * _PATH_TRACE_ is defined.
 458                  *
 459                  * First verify message came from a privileged port. */
 460                 if (ntohs(from->sin_port) > IPPORT_RESERVED) {
 461                         msglog("trace command from untrusted port on %s",
 462                                naddr_ntoa(FROM_NADDR));
 463                         return;
 464                 }
 465                 if (aifp == NULL) {
 466                         msglog("trace command from unknown router %s",
 467                                naddr_ntoa(FROM_NADDR));
 468                         return;
 469                 }
 470                 if (rip->rip_cmd == RIPCMD_TRACEON) {
 471                         rip->rip_tracefile[cc-4] = '\0';
 472                         set_tracefile((char*)rip->rip_tracefile,
 473                                       "trace command: %s\n", 0);
 474                 } else {
 475                         trace_off("tracing turned off by %s",
 476                                   naddr_ntoa(FROM_NADDR));
 477                 }
 478                 return;
 479
 480         case RIPCMD_RESPONSE:
 481                 if (cc%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
 482                         msglim(&bad_len, FROM_NADDR,
 483                                "response of bad length (%d) from %s",
 484                                cc, naddr_ntoa(FROM_NADDR));
 485                 }
 486
 487                 /* verify message came from a router */
 488                 if (from->sin_port != ntohs(RIP_PORT)) {
 489                         msglim(&bad_router, FROM_NADDR,
 490                                "    discard RIP response from unknown port"
 491                                " %d on host %s", ntohs(from->sin_port),
 492                                 naddr_ntoa(FROM_NADDR));
 493                         return;
 494                 }
 495
 496                 if (rip_sock < 0) {
 497                         trace_pkt("    discard response while RIP off");
 498                         return;
 499                 }
 500
 501                 /* Are we talking to ourself or a remote gateway?
 502                  */
 503                 ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
 504                 if (ifp1) {
 505                         if (ifp1->int_state & IS_REMOTE) {
 506                                 /* remote gateway */
 507                                 aifp = ifp1;
 508                                 if (check_remote(aifp)) {
 509                                         aifp->int_act_time = now.tv_sec;
 510                                         if_ok(aifp, "remote ");
 511                                 }
 512                         } else {
 513                                 trace_pkt("    discard our own RIP response");
 514                                 return;
 515                         }
 516                 }
 517
 518                 /* Accept routing packets from routers directly connected
 519                  * via broadcast or point-to-point networks, and from
 520                  * those listed in /etc/gateways.
 521                  */
 522                 if (aifp == NULL) {
 523                         msglim(&unk_router, FROM_NADDR,
 524                                "   discard response from %s"
 525                                " via unexpected interface",
 526                                naddr_ntoa(FROM_NADDR));
 527                         return;
 528                 }
 529                 if (IS_RIP_IN_OFF(aifp->int_state)) {
 530                         trace_pkt("    discard RIPv%d response"
 531                                   " via disabled interface %s",
 532                                   rip->rip_vers, aifp->int_name);
 533                         return;
 534                 }
 535
 536                 if (n >= lim) {
 537                         msglim(&bad_len, FROM_NADDR, "empty response from %s",
 538                                naddr_ntoa(FROM_NADDR));
 539                         return;
 540                 }
 541
 542                 if (((aifp->int_state & IS_NO_RIPV1_IN)
 543                      && rip->rip_vers == RIPv1)
 544                     || ((aifp->int_state & IS_NO_RIPV2_IN)
 545                         && rip->rip_vers != RIPv1)) {
 546                         trace_pkt("    discard RIPv%d response",
 547                                   rip->rip_vers);
 548                         return;
 549                 }
 550
 551                 /* Ignore routes via dead interface.
 552                  */
 553                 if (aifp->int_state & IS_BROKE) {
 554                         trace_pkt("discard response via broken interface %s",
 555                                   aifp->int_name);
 556                         return;
 557                 }
 558
 559                 /* If the interface cares, ignore bad routers.
 560                  * Trace but do not log this problem, because where it
 561                  * happens, it happens frequently.
 562                  */
 563                 if (aifp->int_state & IS_DISTRUST) {
 564                         tg = tgates;
 565                         while (tg->tgate_addr != FROM_NADDR) {
 566                                 tg = tg->tgate_next;
 567                                 if (tg == NULL) {
 568                                         trace_pkt("    discard RIP response"
 569                                                   " from untrusted router %s",
 570                                                   naddr_ntoa(FROM_NADDR));
 571                                         return;
 572                                 }
 573                         }
 574                 }
 575
 576                 /* Authenticate the packet if we have a secret.
 577                  * If we do not have any secrets, ignore the error in
 578                  * RFC 1723 and accept it regardless.
 579                  */
 580                 if (aifp->int_auth[0].type != RIP_AUTH_NONE
 581                     && rip->rip_vers != RIPv1
 582                     && !ck_passwd(aifp,rip,lim,FROM_NADDR,&use_auth))
 583                         return;
 584
 585                 do {
 586                         if (n->n_family == RIP_AF_AUTH)
 587                                 continue;
 588
 589                         n->n_metric = ntohl(n->n_metric);
 590                         dst = n->n_dst;
 591                         if (n->n_family != RIP_AF_INET
 592                             && (n->n_family != RIP_AF_UNSPEC
 593                                 || dst != RIP_DEFAULT)) {
 594                                 msglim(&bad_router, FROM_NADDR,
 595                                        "route from %s to unsupported"
 596                                        " address family=%d destination=%s",
 597                                        naddr_ntoa(FROM_NADDR),
 598                                        n->n_family,
 599                                        naddr_ntoa(dst));
 600                                 continue;
 601                         }
 602                         if (!check_dst(dst)) {
 603                                 msglim(&bad_router, FROM_NADDR,
 604                                        "bad destination %s from %s",
 605                                        naddr_ntoa(dst),
 606                                        naddr_ntoa(FROM_NADDR));
 607                                 return;
 608                         }
 609                         if (n->n_metric == 0
 610                             || n->n_metric > HOPCNT_INFINITY) {
 611                                 msglim(&bad_router, FROM_NADDR,
 612                                        "bad metric %d from %s"
 613                                        " for destination %s",
 614                                        n->n_metric,
 615                                        naddr_ntoa(FROM_NADDR),
 616                                        naddr_ntoa(dst));
 617                                 return;
 618                         }
 619
 620                         /* Notice the next-hop.
 621                          */
 622                         gate = FROM_NADDR;
 623                         if (n->n_nhop != 0) {
 624                                 if (rip->rip_vers == RIPv1) {
 625                                         n->n_nhop = 0;
 626                                 } else {
 627                                     /* Use it only if it is valid. */
 628                                     if (on_net(n->n_nhop,
 629                                                aifp->int_net, aifp->int_mask)
 630                                         && check_dst(n->n_nhop)) {
 631                                             gate = n->n_nhop;
 632                                     } else {
 633                                             msglim(&bad_nhop, FROM_NADDR,
 634                                                    "router %s to %s"
 635                                                    " has bad next hop %s",
 636                                                    naddr_ntoa(FROM_NADDR),
 637                                                    naddr_ntoa(dst),
 638                                                    naddr_ntoa(n->n_nhop));
 639                                             n->n_nhop = 0;
 640                                     }
 641                                 }
 642                         }
 643
 644                         if (rip->rip_vers == RIPv1
 645                             || 0 == (mask = ntohl(n->n_mask))) {
 646                                 mask = ripv1_mask_host(dst,aifp);
 647                         } else if ((ntohl(dst) & ~mask) != 0) {
 648                                 msglim(&bad_mask, FROM_NADDR,
 649                                        "router %s sent bad netmask"
 650                                        " %#lx with %s",
 651                                        naddr_ntoa(FROM_NADDR),
 652                                        (u_long)mask,
 653                                        naddr_ntoa(dst));
 654                                 continue;
 655                         }
 656                         if (rip->rip_vers == RIPv1)
 657                                 n->n_tag = 0;
 658
 659                         /* Adjust metric according to incoming interface..
 660                          */
 661                         n->n_metric += aifp->int_metric;
 662                         if (n->n_metric > HOPCNT_INFINITY)
 663                                 n->n_metric = HOPCNT_INFINITY;
 664
 665                         /* Should we trust this route from this router? */
 666                         if (tg && (tn = tg->tgate_nets)->mask != 0) {
 667                                 for (i = 0; i < MAX_TGATE_NETS; i++, tn++) {
 668                                         if (on_net(dst, tn->net, tn->mask)
 669                                             && tn->mask <= mask)
 670                                             break;
 671                                 }
 672                                 if (i >= MAX_TGATE_NETS || tn->mask == 0) {
 673                                         trace_pkt("   ignored unauthorized %s",
 674                                                   addrname(dst,mask,0));
 675                                         continue;
 676                                 }
 677                         }
 678
 679                         /* Recognize and ignore a default route we faked
 680                          * which is being sent back to us by a machine with
 681                          * broken split-horizon.
 682                          * Be a little more paranoid than that, and reject
 683                          * default routes with the same metric we advertised.
 684                          */
 685                         if (aifp->int_d_metric != 0
 686                             && dst == RIP_DEFAULT
 687                             && (int)n->n_metric >= aifp->int_d_metric)
 688                                 continue;
 689
 690                         /* We can receive aggregated RIPv2 routes that must
 691                          * be broken down before they are transmitted by
 692                          * RIPv1 via an interface on a subnet.
 693                          * We might also receive the same routes aggregated
 694                          * via other RIPv2 interfaces.
 695                          * This could cause duplicate routes to be sent on
 696                          * the RIPv1 interfaces.  "Longest matching variable
 697                          * length netmasks" lets RIPv2 listeners understand,
 698                          * but breaking down the aggregated routes for RIPv1
 699                          * listeners can produce duplicate routes.
 700                          *
 701                          * Breaking down aggregated routes here bloats
 702                          * the daemon table, but does not hurt the kernel
 703                          * table, since routes are always aggregated for
 704                          * the kernel.
 705                          *
 706                          * Notice that this does not break down network
 707                          * routes corresponding to subnets.  This is part
 708                          * of the defense against RS_NET_SYN.
 709                          */
 710                         if (have_ripv1_out
 711                             && (((rt = rtget(dst,mask)) == NULL
 712                                  || !(rt->rt_state & RS_NET_SYN)))
 713                             && (v1_mask = ripv1_mask_net(dst,0)) > mask) {
 714                                 ddst_h = v1_mask & -v1_mask;
 715                                 i = (v1_mask & ~mask)/ddst_h;
 716                                 if (i >= 511) {
 717                                         /* Punt if we would have to generate
 718                                          * an unreasonable number of routes.
 719                                          */
 720                                         if (TRACECONTENTS)
 721                                             trace_misc("accept %s-->%s as 1"
 722                                                        " instead of %d routes",
 723                                                        addrname(dst,mask,0),
 724                                                        naddr_ntoa(FROM_NADDR),
 725                                                        i+1);
 726                                         i = 0;
 727                                 } else {
 728                                         mask = v1_mask;
 729                                 }
 730                         } else {
 731                                 i = 0;
 732                         }
 733
 734                         new.rts_gate = gate;
 735                         new.rts_router = FROM_NADDR;
 736                         new.rts_metric = n->n_metric;
 737                         new.rts_tag = n->n_tag;
 738                         new.rts_time = now.tv_sec;
 739                         new.rts_ifp = aifp;
 740                         new.rts_de_ag = i;
 741                         j = 0;
 742                         for (;;) {
 743                                 input_route(dst, mask, &new, n);
 744                                 if (++j > i)
 745                                         break;
 746                                 dst = htonl(ntohl(dst) + ddst_h);
 747                         }
 748                 } while (++n < lim);
 749                 break;
 750         }
 751 #undef FROM_NADDR
 752 }
 753
 754
 755 /* Process a single input route.
 756  */
 757 static void
 758 input_route(naddr dst,                  /* network order */
 759             naddr mask,
 760             struct rt_spare *new,
 761             struct netinfo *n)
 762 {
 763         int i;
 764         struct rt_entry *rt;
 765         struct rt_spare *rts, *rts0;
 766         struct interface *ifp1;
 767
 768
 769         /* See if the other guy is telling us to send our packets to him.
 770          * Sometimes network routes arrive over a point-to-point link for
 771          * the network containing the address(es) of the link.
 772          *
 773          * If our interface is broken, switch to using the other guy.
 774          */
 775         ifp1 = ifwithaddr(dst, 1, 1);
 776         if (ifp1 != NULL
 777             && (!(ifp1->int_state & IS_BROKE)
 778                 || (ifp1->int_state & IS_PASSIVE)))
 779                 return;
 780
 781         /* Look for the route in our table.
 782          */
 783         rt = rtget(dst, mask);
 784
 785         /* Consider adding the route if we do not already have it.
 786          */
 787         if (rt == NULL) {
 788                 /* Ignore unknown routes being poisoned.
 789                  */
 790                 if (new->rts_metric == HOPCNT_INFINITY)
 791                         return;
 792
 793                 /* Ignore the route if it points to us */
 794                 if (n->n_nhop != 0
 795                     && 0 != ifwithaddr(n->n_nhop, 1, 0))
 796                         return;
 797
 798                 /* If something has not gone crazy and tried to fill
 799                  * our memory, accept the new route.
 800                  */
 801                 if (total_routes < MAX_ROUTES)
 802                         rtadd(dst, mask, 0, new);
 803                 return;
 804         }
 805
 806         /* We already know about the route.  Consider this update.
 807          *
 808          * If (rt->rt_state & RS_NET_SYN), then this route
 809          * is the same as a network route we have inferred
 810          * for subnets we know, in order to tell RIPv1 routers
 811          * about the subnets.
 812          *
 813          * It is impossible to tell if the route is coming
 814          * from a distant RIPv2 router with the standard
 815          * netmask because that router knows about the entire
 816          * network, or if it is a round-about echo of a
 817          * synthetic, RIPv1 network route of our own.
 818          * The worst is that both kinds of routes might be
 819          * received, and the bad one might have the smaller
 820          * metric.  Partly solve this problem by never
 821          * aggregating into such a route.  Also keep it
 822          * around as long as the interface exists.
 823          */
 824
 825         rts0 = rt->rt_spares;
 826         for (rts = rts0, i = NUM_SPARES; i != 0; i--, rts++) {
 827                 if (rts->rts_router == new->rts_router)
 828                         break;
 829                 /* Note the worst slot to reuse,
 830                  * other than the current slot.
 831                  */
 832                 if (rts0 == rt->rt_spares
 833                     || BETTER_LINK(rt, rts0, rts))
 834                         rts0 = rts;
 835         }
 836         if (i != 0) {
 837                 /* Found a route from the router already in the table.
 838                  */
 839
 840                 /* If the new route is a route broken down from an
 841                  * aggregated route, and if the previous route is either
 842                  * not a broken down route or was broken down from a finer
 843                  * netmask, and if the previous route is current,
 844                  * then forget this one.
 845                  */
 846                 if (new->rts_de_ag > rts->rts_de_ag
 847                     && now_stale <= rts->rts_time)
 848                         return;
 849
 850                 /* Keep poisoned routes around only long enough to pass
 851                  * the poison on.  Use a new timestamp for good routes.
 852                  */
 853                 if (rts->rts_metric == HOPCNT_INFINITY
 854                     && new->rts_metric == HOPCNT_INFINITY)
 855                         new->rts_time = rts->rts_time;
 856
 857                 /* If this is an update for the router we currently prefer,
 858                  * then note it.
 859                  */
 860                 if (i == NUM_SPARES) {
 861                         rtchange(rt, rt->rt_state, new, 0);
 862                         /* If the route got worse, check for something better.
 863                          */
 864                         if (new->rts_metric > rts->rts_metric)
 865                                 rtswitch(rt, 0);
 866                         return;
 867                 }
 868
 869                 /* This is an update for a spare route.
 870                  * Finished if the route is unchanged.
 871                  */
 872                 if (rts->rts_gate == new->rts_gate
 873                     && rts->rts_metric == new->rts_metric
 874                     && rts->rts_tag == new->rts_tag) {
 875                         trace_upslot(rt, rts, new);
 876                         *rts = *new;
 877                         return;
 878                 }
 879                 /* Forget it if it has gone bad.
 880                  */
 881                 if (new->rts_metric == HOPCNT_INFINITY) {
 882                         rts_delete(rt, rts);
 883                         return;
 884                 }
 885
 886         } else {
 887                 /* The update is for a route we know about,
 888                  * but not from a familiar router.
 889                  *
 890                  * Ignore the route if it points to us.
 891                  */
 892                 if (n->n_nhop != 0
 893                     && 0 != ifwithaddr(n->n_nhop, 1, 0))
 894                         return;
 895
 896                 /* the loop above set rts0=worst spare */
 897                 rts = rts0;
 898
 899                 /* Save the route as a spare only if it has
 900                  * a better metric than our worst spare.
 901                  * This also ignores poisoned routes (those
 902                  * received with metric HOPCNT_INFINITY).
 903                  */
 904                 if (new->rts_metric >= rts->rts_metric)
 905                         return;
 906         }
 907
 908         trace_upslot(rt, rts, new);
 909         *rts = *new;
 910
 911         /* try to switch to a better route */
 912         rtswitch(rt, rts);
 913 }
 914
 915
 916 static int                              /* 0 if bad */
 917 ck_passwd(struct interface *aifp,
 918           struct rip *rip,
 919           void *lim,
 920           naddr from,
 921           struct msg_limit *use_authp)
 922 {
 923 #       define NA (rip->rip_auths)
 924         struct netauth *na2;
 925         struct auth *ap;
 926         MD5_CTX md5_ctx;
 927         u_char hash[RIP_AUTH_PW_LEN];
 928         int i, len;
 929
 930
 931         if ((void *)NA >= lim || NA->a_family != RIP_AF_AUTH) {
 932                 msglim(use_authp, from, "missing password from %s",
 933                        naddr_ntoa(from));
 934                 return 0;
 935         }
 936
 937         /* accept any current (+/- 24 hours) password
 938          */
 939         for (ap = aifp->int_auth, i = 0; i < MAX_AUTH_KEYS; i++, ap++) {
 940                 if (ap->type != NA->a_type
 941                     || (u_long)ap->start > (u_long)clk.tv_sec+DAY
 942                     || (u_long)ap->end+DAY < (u_long)clk.tv_sec)
 943                         continue;
 944
 945                 if (NA->a_type == RIP_AUTH_PW) {
 946                         if (!memcmp(NA->au.au_pw, ap->key, RIP_AUTH_PW_LEN))
 947                                 return 1;
 948
 949                 } else {
 950                         /* accept MD5 secret with the right key ID
 951                          */
 952                         if (NA->au.a_md5.md5_keyid != ap->keyid)
 953                                 continue;
 954
 955                         len = ntohs(NA->au.a_md5.md5_pkt_len);
 956                         if ((len-sizeof(*rip)) % sizeof(*NA) != 0
 957                             || len != (char *)lim-(char*)rip-(int)sizeof(*NA)) {
 958                                 msglim(use_authp, from,
 959                                        "wrong MD5 RIPv2 packet length of %d"
 960                                        " instead of %d from %s",
 961                                        len, (int)((char *)lim-(char *)rip
 962                                                   -sizeof(*NA)),
 963                                        naddr_ntoa(from));
 964                                 return 0;
 965                         }
 966                         na2 = (struct netauth *)((char *)rip+len);
 967
 968                         /* Given a good hash value, these are not security
 969                          * problems so be generous and accept the routes,
 970                          * after complaining.
 971                          */
 972                         if (TRACEPACKETS) {
 973                                 if (NA->au.a_md5.md5_auth_len
 974                                     != RIP_AUTH_MD5_LEN)
 975                                         msglim(use_authp, from,
 976                                                "unknown MD5 RIPv2 auth len %#x"
 977                                                " instead of %#x from %s",
 978                                                NA->au.a_md5.md5_auth_len,
 979                                                RIP_AUTH_MD5_LEN,
 980                                                naddr_ntoa(from));
 981                                 if (na2->a_family != RIP_AF_AUTH)
 982                                         msglim(use_authp, from,
 983                                                "unknown MD5 RIPv2 family %#x"
 984                                                " instead of %#x from %s",
 985                                                na2->a_family, RIP_AF_AUTH,
 986                                                naddr_ntoa(from));
 987                                 if (na2->a_type != ntohs(1))
 988                                         msglim(use_authp, from,
 989                                                "MD5 RIPv2 hash has %#x"
 990                                                " instead of %#x from %s",
 991                                                na2->a_type, ntohs(1),
 992                                                naddr_ntoa(from));
 993                         }
 994
 995                         MD5Init(&md5_ctx);
 996                         MD5Update(&md5_ctx, (u_char *)rip, len);
 997                         MD5Update(&md5_ctx, ap->key, RIP_AUTH_MD5_LEN);
 998                         MD5Final(hash, &md5_ctx);
 999                         if (!memcmp(hash, na2->au.au_pw, sizeof(hash)))
1000                                 return 1;
1001                 }
1002         }
1003
1004         msglim(use_authp, from, "bad password from %s",
1005                naddr_ntoa(from));
1006         return 0;
1007 #undef NA
1008 }