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