1 /* $NetBSD: rdisc.c,v 1.4 1996/09/24 16:24:20 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #if !defined(lint) && !defined(sgi) && !defined(__NetBSD__) 37 static char sccsid[] = "@(#)rdisc.c 8.1 (Berkeley) x/y/95"; 38 #elif defined(__NetBSD__) 39 static char rcsid[] = "$NetBSD: rdisc.c,v 1.4 1996/09/24 16:24:20 christos Exp $"; 40 #endif 41 42 #include "defs.h" 43 #include <netinet/in_systm.h> 44 #include <netinet/ip.h> 45 #include <netinet/ip_icmp.h> 46 47 /* router advertisement ICMP packet */ 48 struct icmp_ad { 49 u_int8_t icmp_type; /* type of message */ 50 u_int8_t icmp_code; /* type sub code */ 51 u_int16_t icmp_cksum; /* ones complement cksum of struct */ 52 u_int8_t icmp_ad_num; /* # of following router addresses */ 53 u_int8_t icmp_ad_asize; /* 2--words in each advertisement */ 54 u_int16_t icmp_ad_life; /* seconds of validity */ 55 struct icmp_ad_info { 56 n_long icmp_ad_addr; 57 n_long icmp_ad_pref; 58 } icmp_ad_info[1]; 59 }; 60 61 /* router solicitation ICMP packet */ 62 struct icmp_so { 63 u_int8_t icmp_type; /* type of message */ 64 u_int8_t icmp_code; /* type sub code */ 65 u_int16_t icmp_cksum; /* ones complement cksum of struct */ 66 n_long icmp_so_rsvd; 67 }; 68 69 union ad_u { 70 struct icmp icmp; 71 struct icmp_ad ad; 72 struct icmp_so so; 73 }; 74 75 76 int rdisc_sock = -1; /* router-discovery raw socket */ 77 struct interface *rdisc_sock_mcast; /* current multicast interface */ 78 79 struct timeval rdisc_timer; 80 int rdisc_ok; /* using solicited route */ 81 82 83 #define MAX_ADS 5 84 struct dr { /* accumulated advertisements */ 85 struct interface *dr_ifp; 86 naddr dr_gate; /* gateway */ 87 time_t dr_ts; /* when received */ 88 time_t dr_life; /* lifetime */ 89 n_long dr_recv_pref; /* received but biased preference */ 90 n_long dr_pref; /* preference adjusted by metric */ 91 } *cur_drp, drs[MAX_ADS]; 92 93 /* adjust preference by interface metric without driving it to infinity */ 94 #define PREF(p, ifp) ((p) <= (ifp)->int_metric ? ((p) != 0 ? 1 : 0) \ 95 : (p) - ((ifp)->int_metric)) 96 97 static void rdisc_sort(void); 98 99 100 /* dump an ICMP Router Discovery Advertisement Message 101 */ 102 static void 103 trace_rdisc(char *act, 104 naddr from, 105 naddr to, 106 struct interface *ifp, 107 union ad_u *p, 108 u_int len) 109 { 110 int i; 111 n_long *wp, *lim; 112 113 114 if (!TRACEPACKETS || ftrace == 0) 115 return; 116 117 lastlog(); 118 119 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) { 120 (void)fprintf(ftrace, "%s Router Ad" 121 " from %s to %s via %s life=%d\n", 122 act, naddr_ntoa(from), naddr_ntoa(to), 123 ifp ? ifp->int_name : "?", 124 ntohs(p->ad.icmp_ad_life)); 125 if (!TRACECONTENTS) 126 return; 127 128 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr; 129 lim = &wp[(len - sizeof(p->ad)) / sizeof(*wp)]; 130 for (i = 0; i < p->ad.icmp_ad_num && wp <= lim; i++) { 131 (void)fprintf(ftrace, "\t%s preference=%#x", 132 naddr_ntoa(wp[0]), (int)ntohl(wp[1])); 133 wp += p->ad.icmp_ad_asize; 134 } 135 (void)fputc('\n',ftrace); 136 137 } else { 138 trace_act("%s Router Solic. from %s to %s via %s" 139 " value=%#x\n", 140 act, naddr_ntoa(from), naddr_ntoa(to), 141 ifp ? ifp->int_name : "?", 142 ntohl(p->so.icmp_so_rsvd)); 143 } 144 } 145 146 /* prepare Router Discovery socket. 147 */ 148 static void 149 get_rdisc_sock(void) 150 { 151 if (rdisc_sock < 0) { 152 rdisc_sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); 153 if (rdisc_sock < 0) 154 BADERR(1,"rdisc_sock = socket()"); 155 fix_sock(rdisc_sock,"rdisc_sock"); 156 fix_select(); 157 } 158 } 159 160 161 /* Pick multicast group for router-discovery socket 162 */ 163 void 164 set_rdisc_mg(struct interface *ifp, 165 int on) { /* 0=turn it off */ 166 struct ip_mreq m; 167 168 if (rdisc_sock < 0) { 169 /* Create the raw socket so that we can hear at least 170 * broadcast router discovery packets. 171 */ 172 if ((ifp->int_state & IS_NO_RDISC) == IS_NO_RDISC 173 || !on) 174 return; 175 get_rdisc_sock(); 176 } 177 178 if (!(ifp->int_if_flags & IFF_MULTICAST) 179 || (ifp->int_state & IS_ALIAS)) { 180 ifp->int_state &= ~(IS_ALL_HOSTS | IS_ALL_ROUTERS); 181 return; 182 } 183 184 #ifdef MCAST_PPP_BUG 185 if (ifp->int_if_flags & IFF_POINTOPOINT) 186 return; 187 #endif 188 bzero(&m, sizeof(m)); 189 m.imr_interface.s_addr = ((ifp->int_if_flags & IFF_POINTOPOINT) 190 ? ifp->int_dstaddr 191 : ifp->int_addr); 192 if (supplier 193 || (ifp->int_state & IS_NO_ADV_IN) 194 || !on) { 195 /* stop listening to advertisements 196 */ 197 if (ifp->int_state & IS_ALL_HOSTS) { 198 m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP); 199 if (setsockopt(rdisc_sock, IPPROTO_IP, 200 IP_DROP_MEMBERSHIP, 201 &m, sizeof(m)) < 0) 202 LOGERR("IP_DROP_MEMBERSHIP ALLHOSTS"); 203 ifp->int_state &= ~IS_ALL_HOSTS; 204 } 205 206 } else if (!(ifp->int_state & IS_ALL_HOSTS)) { 207 /* start listening to advertisements 208 */ 209 m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP); 210 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, 211 &m, sizeof(m)) < 0) { 212 LOGERR("IP_ADD_MEMBERSHIP ALLHOSTS"); 213 } else { 214 ifp->int_state |= IS_ALL_HOSTS; 215 } 216 } 217 218 if (!supplier 219 || (ifp->int_state & IS_NO_ADV_OUT) 220 || !on) { 221 /* stop listening to solicitations 222 */ 223 if (ifp->int_state & IS_ALL_ROUTERS) { 224 m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP); 225 if (setsockopt(rdisc_sock, IPPROTO_IP, 226 IP_DROP_MEMBERSHIP, 227 &m, sizeof(m)) < 0) 228 LOGERR("IP_DROP_MEMBERSHIP ALLROUTERS"); 229 ifp->int_state &= ~IS_ALL_ROUTERS; 230 } 231 232 } else if (!(ifp->int_state & IS_ALL_ROUTERS)) { 233 /* start hearing solicitations 234 */ 235 m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP); 236 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, 237 &m, sizeof(m)) < 0) { 238 LOGERR("IP_ADD_MEMBERSHIP ALLROUTERS"); 239 } else { 240 ifp->int_state |= IS_ALL_ROUTERS; 241 } 242 } 243 } 244 245 246 /* start supplying routes 247 */ 248 void 249 set_supplier(void) 250 { 251 struct interface *ifp; 252 struct dr *drp; 253 254 if (supplier_set) 255 return; 256 257 trace_act("start suppying routes\n"); 258 259 /* Forget discovered routes. 260 */ 261 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 262 drp->dr_recv_pref = 0; 263 drp->dr_life = 0; 264 } 265 rdisc_age(0); 266 267 supplier_set = 1; 268 supplier = 1; 269 270 /* Do not start advertising until we have heard some RIP routes */ 271 LIM_SEC(rdisc_timer, now.tv_sec+MIN_WAITTIME); 272 273 /* Switch router discovery multicast groups from soliciting 274 * to advertising. 275 */ 276 for (ifp = ifnet; ifp; ifp = ifp->int_next) { 277 if (ifp->int_state & IS_BROKE) 278 continue; 279 ifp->int_rdisc_cnt = 0; 280 ifp->int_rdisc_timer.tv_usec = rdisc_timer.tv_usec; 281 ifp->int_rdisc_timer.tv_sec = now.tv_sec+MIN_WAITTIME; 282 set_rdisc_mg(ifp, 1); 283 } 284 285 /* get rid of any redirects */ 286 del_redirects(0,0); 287 } 288 289 290 /* age discovered routes and find the best one 291 */ 292 void 293 rdisc_age(naddr bad_gate) 294 { 295 time_t sec; 296 struct dr *drp; 297 298 299 /* If only adverising, then do only that. */ 300 if (supplier) { 301 /* if switching from client to server, get rid of old 302 * default routes. 303 */ 304 if (cur_drp != 0) 305 rdisc_sort(); 306 rdisc_adv(); 307 return; 308 } 309 310 /* If we are being told about a bad router, 311 * then age the discovered default route, and if there is 312 * no alternative, solicite a replacement. 313 */ 314 if (bad_gate != 0) { 315 /* Look for the bad discovered default route. 316 * Age it and note its interface. 317 */ 318 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 319 if (drp->dr_ts == 0) 320 continue; 321 322 /* When we find the bad router, then age the route 323 * to at most SUPPLY_INTERVAL. 324 * This is contrary to RFC 1256, but defends against 325 * black holes. 326 */ 327 if (drp->dr_gate == bad_gate) { 328 sec = (now.tv_sec - drp->dr_life 329 + SUPPLY_INTERVAL); 330 if (drp->dr_ts > sec) { 331 trace_act("age 0.0.0.0 --> %s" 332 " via %s\n", 333 naddr_ntoa(drp->dr_gate), 334 drp->dr_ifp->int_name); 335 drp->dr_ts = sec; 336 } 337 break; 338 } 339 } 340 } 341 342 /* delete old redirected routes to keep the kernel table small 343 */ 344 sec = (cur_drp == 0) ? MaxMaxAdvertiseInterval : cur_drp->dr_life; 345 del_redirects(bad_gate, now.tv_sec-sec); 346 347 rdisc_sol(); 348 349 rdisc_sort(); 350 } 351 352 353 /* Zap all routes discovered via an interface that has gone bad 354 * This should only be called when !(ifp->int_state & IS_ALIAS) 355 */ 356 void 357 if_bad_rdisc(struct interface *ifp) 358 { 359 struct dr *drp; 360 361 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 362 if (drp->dr_ifp != ifp) 363 continue; 364 drp->dr_recv_pref = 0; 365 drp->dr_life = 0; 366 } 367 368 rdisc_sort(); 369 } 370 371 372 /* mark an interface ok for router discovering. 373 */ 374 void 375 if_ok_rdisc(struct interface *ifp) 376 { 377 set_rdisc_mg(ifp, 1); 378 379 ifp->int_rdisc_cnt = 0; 380 ifp->int_rdisc_timer.tv_sec = now.tv_sec + (supplier 381 ? MIN_WAITTIME 382 : MAX_SOLICITATION_DELAY); 383 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 384 rdisc_timer = ifp->int_rdisc_timer; 385 } 386 387 388 /* get rid of a dead discovered router 389 */ 390 static void 391 del_rdisc(struct dr *drp) 392 { 393 struct interface *ifp; 394 int i; 395 396 397 del_redirects(drp->dr_gate, 0); 398 drp->dr_ts = 0; 399 drp->dr_life = 0; 400 401 402 /* Count the other discovered routes on the interface. 403 */ 404 i = 0; 405 ifp = drp->dr_ifp; 406 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 407 if (drp->dr_ts != 0 408 && drp->dr_ifp == ifp) 409 i++; 410 } 411 412 /* If that was the last good discovered router on the interface, 413 * then solicit a new one. 414 * This is contrary to RFC 1256, but defends against black holes. 415 */ 416 if (i == 0 417 && ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) { 418 trace_act("discovered route is bad" 419 "--re-solicit routers via %s\n", ifp->int_name); 420 ifp->int_rdisc_cnt = 0; 421 ifp->int_rdisc_timer.tv_sec = 0; 422 rdisc_sol(); 423 } 424 } 425 426 427 /* Find the best discovered route, 428 * and discard stale routers. 429 */ 430 static void 431 rdisc_sort(void) 432 { 433 struct dr *drp, *new_drp; 434 struct rt_entry *rt; 435 struct interface *ifp; 436 u_int new_st; 437 n_long new_pref; 438 439 440 /* Find the best discovered route. 441 */ 442 new_drp = 0; 443 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 444 if (drp->dr_ts == 0) 445 continue; 446 ifp = drp->dr_ifp; 447 448 /* Get rid of expired discovered routers. 449 */ 450 if (drp->dr_ts + drp->dr_life <= now.tv_sec) { 451 del_rdisc(drp); 452 continue; 453 } 454 455 LIM_SEC(rdisc_timer, drp->dr_ts+drp->dr_life+1); 456 457 /* Update preference with possibly changed interface 458 * metric. 459 */ 460 drp->dr_pref = PREF(drp->dr_recv_pref, ifp); 461 462 /* Prefer the current route to prevent thrashing. 463 * Prefer shorter lifetimes to speed the detection of 464 * bad routers. 465 * Avoid sick interfaces. 466 */ 467 if (new_drp == 0 468 || (!((new_st ^ drp->dr_ifp->int_state) & IS_SICK) 469 && (new_pref < drp->dr_pref 470 || (new_pref == drp->dr_pref 471 && (drp == cur_drp 472 || (new_drp != cur_drp 473 && new_drp->dr_life > drp->dr_life))))) 474 || ((new_st & IS_SICK) 475 && !(drp->dr_ifp->int_state & IS_SICK))) { 476 new_drp = drp; 477 new_st = drp->dr_ifp->int_state; 478 new_pref = drp->dr_pref; 479 } 480 } 481 482 /* switch to a better default route 483 */ 484 if (new_drp != cur_drp) { 485 rt = rtget(RIP_DEFAULT, 0); 486 487 /* Stop using discovered routes if they are all bad 488 */ 489 if (new_drp == 0) { 490 trace_act("turn off Router Discovery client\n"); 491 rdisc_ok = 0; 492 493 if (rt != 0 494 && (rt->rt_state & RS_RDISC)) { 495 rtchange(rt, rt->rt_state & ~RS_RDISC, 496 rt->rt_gate, rt->rt_router, 497 HOPCNT_INFINITY, 0, rt->rt_ifp, 498 now.tv_sec - GARBAGE_TIME, 0); 499 rtswitch(rt, 0); 500 } 501 502 /* turn on RIP if permitted */ 503 rip_on(0); 504 505 } else { 506 if (cur_drp == 0) { 507 trace_act("turn on Router Discovery client" 508 " using %s via %s\n", 509 naddr_ntoa(new_drp->dr_gate), 510 new_drp->dr_ifp->int_name); 511 512 rdisc_ok = 1; 513 514 } else { 515 trace_act("switch Router Discovery from" 516 " %s via %s to %s via %s\n", 517 naddr_ntoa(cur_drp->dr_gate), 518 cur_drp->dr_ifp->int_name, 519 naddr_ntoa(new_drp->dr_gate), 520 new_drp->dr_ifp->int_name); 521 } 522 523 if (rt != 0) { 524 rtchange(rt, rt->rt_state | RS_RDISC, 525 new_drp->dr_gate, new_drp->dr_gate, 526 0,0, new_drp->dr_ifp, 527 now.tv_sec, 0); 528 } else { 529 rtadd(RIP_DEFAULT, 0, 530 new_drp->dr_gate, new_drp->dr_gate, 531 0, 0, RS_RDISC, new_drp->dr_ifp); 532 } 533 534 /* Now turn off RIP and delete RIP routes, 535 * which might otherwise include the default 536 * we just modified. 537 */ 538 rip_off(); 539 } 540 541 cur_drp = new_drp; 542 } 543 } 544 545 546 /* handle a single address in an advertisement 547 */ 548 static void 549 parse_ad(naddr from, 550 naddr gate, 551 n_long pref, 552 u_short life, 553 struct interface *ifp) 554 { 555 static naddr bad_gate; 556 struct dr *drp, *new_drp; 557 558 559 if (gate == RIP_DEFAULT 560 || !check_dst(gate)) { 561 if (bad_gate != from) { 562 msglog("router %s advertising bad gateway %s", 563 naddr_ntoa(from), 564 naddr_ntoa(gate)); 565 bad_gate = from; 566 } 567 return; 568 } 569 570 /* ignore pointers to ourself and routes via unreachable networks 571 */ 572 if (ifwithaddr(gate, 1, 0) != 0) { 573 trace_pkt("\tdiscard Router Discovery Ad pointing at us\n"); 574 return; 575 } 576 if (!on_net(gate, ifp->int_net, ifp->int_mask)) { 577 trace_pkt("\tdiscard Router Discovery Ad" 578 " toward unreachable net\n"); 579 return; 580 } 581 582 /* Convert preference to an unsigned value 583 * and later bias it by the metric of the interface. 584 */ 585 pref = ntohl(pref) ^ MIN_PreferenceLevel; 586 587 if (pref == 0 || life == 0) { 588 pref = 0; 589 life = 0; 590 } 591 592 for (new_drp = 0, drp = drs; drp < &drs[MAX_ADS]; drp++) { 593 /* accept new info for a familiar entry 594 */ 595 if (drp->dr_gate == gate) { 596 new_drp = drp; 597 break; 598 } 599 600 if (life == 0) 601 continue; /* do not worry about dead ads */ 602 603 if (drp->dr_ts == 0) { 604 new_drp = drp; /* use unused entry */ 605 606 } else if (new_drp == 0) { 607 /* look for an entry worse than the new one to 608 * reuse. 609 */ 610 if ((!(ifp->int_state & IS_SICK) 611 && (drp->dr_ifp->int_state & IS_SICK)) 612 || (pref > drp->dr_pref 613 && !((ifp->int_state ^ drp->dr_ifp->int_state) 614 & IS_SICK))) 615 new_drp = drp; 616 617 } else if (new_drp->dr_ts != 0) { 618 /* look for the least valueable entry to reuse 619 */ 620 if ((!(new_drp->dr_ifp->int_state & IS_SICK) 621 && (drp->dr_ifp->int_state & IS_SICK)) 622 || (new_drp->dr_pref > drp->dr_pref 623 && !((new_drp->dr_ifp->int_state 624 ^ drp->dr_ifp->int_state) 625 & IS_SICK))) 626 new_drp = drp; 627 } 628 } 629 630 /* forget it if all of the current entries are better */ 631 if (new_drp == 0) 632 return; 633 634 new_drp->dr_ifp = ifp; 635 new_drp->dr_gate = gate; 636 new_drp->dr_ts = now.tv_sec; 637 new_drp->dr_life = ntohs(life); 638 new_drp->dr_recv_pref = pref; 639 /* bias functional preference by metric of the interface */ 640 new_drp->dr_pref = PREF(pref,ifp); 641 642 /* after hearing a good advertisement, stop asking 643 */ 644 if (!(ifp->int_state & IS_SICK)) 645 ifp->int_rdisc_cnt = MAX_SOLICITATIONS; 646 } 647 648 649 /* Compute the IP checksum 650 * This assumes the packet is less than 32K long. 651 */ 652 static u_short 653 in_cksum(u_short *p, 654 u_int len) 655 { 656 u_int sum = 0; 657 int nwords = len >> 1; 658 659 while (nwords-- != 0) 660 sum += *p++; 661 662 if (len & 1) 663 sum += *(u_char *)p; 664 665 /* end-around-carry */ 666 sum = (sum >> 16) + (sum & 0xffff); 667 sum += (sum >> 16); 668 return (~sum); 669 } 670 671 672 /* Send a router discovery advertisement or solicitation ICMP packet. 673 */ 674 static void 675 send_rdisc(union ad_u *p, 676 int p_size, 677 struct interface *ifp, 678 naddr dst, /* 0 or unicast destination */ 679 int type) /* 0=unicast, 1=bcast, 2=mcast */ 680 { 681 struct sockaddr_in sin; 682 int flags; 683 char *msg; 684 naddr tgt_mcast; 685 686 687 bzero(&sin, sizeof(sin)); 688 sin.sin_addr.s_addr = dst; 689 sin.sin_family = AF_INET; 690 #ifdef _HAVE_SIN_LEN 691 sin.sin_len = sizeof(sin); 692 #endif 693 flags = MSG_DONTROUTE; 694 695 switch (type) { 696 case 0: /* unicast */ 697 msg = "Send"; 698 break; 699 700 case 1: /* broadcast */ 701 if (ifp->int_if_flags & IFF_POINTOPOINT) { 702 msg = "Send pt-to-pt"; 703 sin.sin_addr.s_addr = ifp->int_dstaddr; 704 } else { 705 msg = "Send broadcast"; 706 sin.sin_addr.s_addr = ifp->int_brdaddr; 707 } 708 break; 709 710 case 2: /* multicast */ 711 msg = "Send multicast"; 712 if (ifp->int_state & IS_DUP) { 713 trace_act("abort multicast output via %s" 714 " with duplicate address\n", 715 ifp->int_name); 716 return; 717 } 718 if (rdisc_sock_mcast != ifp) { 719 /* select the right interface. */ 720 #ifdef MCAST_PPP_BUG 721 /* Do not specifiy the primary interface explicitly 722 * if we have the multicast point-to-point kernel 723 * bug, since the kernel will do the wrong thing 724 * if the local address of a point-to-point link 725 * is the same as the address of an ordinary 726 * interface. 727 */ 728 if (ifp->int_addr == myaddr) { 729 tgt_mcast = 0; 730 } else 731 #endif 732 tgt_mcast = ifp->int_addr; 733 if (0 > setsockopt(rdisc_sock, 734 IPPROTO_IP, IP_MULTICAST_IF, 735 &tgt_mcast, sizeof(tgt_mcast))) { 736 LOGERR("setsockopt(rdisc_sock," 737 "IP_MULTICAST_IF)"); 738 rdisc_sock_mcast = 0; 739 return; 740 } 741 rdisc_sock_mcast = ifp; 742 } 743 flags = 0; 744 break; 745 } 746 747 if (rdisc_sock < 0) 748 get_rdisc_sock(); 749 750 trace_rdisc(msg, ifp->int_addr, sin.sin_addr.s_addr, ifp, 751 p, p_size); 752 753 if (0 > sendto(rdisc_sock, p, p_size, flags, 754 (struct sockaddr *)&sin, sizeof(sin))) { 755 if (ifp == 0 || !(ifp->int_state & IS_BROKE)) 756 msglog("sendto(%s%s%s): %s", 757 ifp != 0 ? ifp->int_name : "", 758 ifp != 0 ? ", " : "", 759 inet_ntoa(sin.sin_addr), 760 strerror(errno)); 761 if (ifp != 0) 762 if_sick(ifp); 763 } 764 } 765 766 767 /* Send an advertisement 768 */ 769 static void 770 send_adv(struct interface *ifp, 771 naddr dst, /* 0 or unicast destination */ 772 int type) /* 0=unicast, 1=bcast, 2=mcast */ 773 { 774 union ad_u u; 775 n_long pref; 776 777 778 bzero(&u,sizeof(u.ad)); 779 780 u.ad.icmp_type = ICMP_ROUTERADVERT; 781 u.ad.icmp_ad_num = 1; 782 u.ad.icmp_ad_asize = sizeof(u.ad.icmp_ad_info[0])/4; 783 784 u.ad.icmp_ad_life = stopint ? 0 : htons(ifp->int_rdisc_int*3); 785 pref = ifp->int_rdisc_pref ^ MIN_PreferenceLevel; 786 pref = PREF(pref, ifp) ^ MIN_PreferenceLevel; 787 u.ad.icmp_ad_info[0].icmp_ad_pref = htonl(pref); 788 789 u.ad.icmp_ad_info[0].icmp_ad_addr = ifp->int_addr; 790 791 u.ad.icmp_cksum = in_cksum((u_short*)&u.ad, sizeof(u.ad)); 792 793 send_rdisc(&u, sizeof(u.ad), ifp, dst, type); 794 } 795 796 797 /* Advertise for Router Discovery 798 */ 799 void 800 rdisc_adv(void) 801 { 802 struct interface *ifp; 803 804 805 rdisc_timer.tv_sec = now.tv_sec + NEVER; 806 807 for (ifp = ifnet; ifp; ifp = ifp->int_next) { 808 if (0 != (ifp->int_state & (IS_NO_ADV_OUT 809 | IS_PASSIVE 810 | IS_ALIAS 811 | IS_BROKE))) 812 continue; 813 814 if (!timercmp(&ifp->int_rdisc_timer, &now, >) 815 || stopint) { 816 send_adv(ifp, htonl(INADDR_ALLHOSTS_GROUP), 817 (ifp->int_state&IS_BCAST_RDISC) ? 1 : 2); 818 ifp->int_rdisc_cnt++; 819 820 intvl_random(&ifp->int_rdisc_timer, 821 (ifp->int_rdisc_int*3)/4, 822 ifp->int_rdisc_int); 823 if (ifp->int_rdisc_cnt < MAX_INITIAL_ADVERTS 824 && (ifp->int_rdisc_timer.tv_sec 825 > MAX_INITIAL_ADVERT_INTERVAL)) { 826 ifp->int_rdisc_timer.tv_sec 827 = MAX_INITIAL_ADVERT_INTERVAL; 828 } 829 timevaladd(&ifp->int_rdisc_timer, &now); 830 } 831 832 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 833 rdisc_timer = ifp->int_rdisc_timer; 834 } 835 } 836 837 838 /* Solicit for Router Discovery 839 */ 840 void 841 rdisc_sol(void) 842 { 843 struct interface *ifp; 844 union ad_u u; 845 846 847 rdisc_timer.tv_sec = now.tv_sec + NEVER; 848 849 for (ifp = ifnet; ifp; ifp = ifp->int_next) { 850 if (0 != (ifp->int_state & (IS_NO_SOL_OUT 851 | IS_PASSIVE 852 | IS_ALIAS 853 | IS_BROKE)) 854 || ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) 855 continue; 856 857 if (!timercmp(&ifp->int_rdisc_timer, &now, >)) { 858 bzero(&u,sizeof(u.so)); 859 u.so.icmp_type = ICMP_ROUTERSOLICIT; 860 u.so.icmp_cksum = in_cksum((u_short*)&u.so, 861 sizeof(u.so)); 862 send_rdisc(&u, sizeof(u.so), ifp, 863 htonl(INADDR_ALLROUTERS_GROUP), 864 ((ifp->int_state&IS_BCAST_RDISC) ? 1 : 2)); 865 866 if (++ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) 867 continue; 868 869 ifp->int_rdisc_timer.tv_sec = SOLICITATION_INTERVAL; 870 ifp->int_rdisc_timer.tv_usec = 0; 871 timevaladd(&ifp->int_rdisc_timer, &now); 872 } 873 874 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 875 rdisc_timer = ifp->int_rdisc_timer; 876 } 877 } 878 879 880 /* check the IP header of a possible Router Discovery ICMP packet */ 881 static struct interface * /* 0 if bad */ 882 ck_icmp(char *act, 883 naddr from, 884 naddr to, 885 union ad_u *p, 886 u_int len) 887 { 888 struct interface *ifp; 889 char *type; 890 891 892 /* If we could tell the interface on which a packet from address 0 893 * arrived, we could deal with such solicitations. 894 */ 895 896 ifp = ((from == 0) ? 0 : iflookup(from)); 897 898 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) { 899 type = "advertisement"; 900 } else if (p->icmp.icmp_type == ICMP_ROUTERSOLICIT) { 901 type = "solicitation"; 902 } else { 903 return 0; 904 } 905 906 if (p->icmp.icmp_code != 0) { 907 trace_pkt("unrecognized ICMP Router" 908 " %s code=%d from %s to %s\n", 909 type, p->icmp.icmp_code, 910 naddr_ntoa(from), naddr_ntoa(to)); 911 return 0; 912 } 913 914 trace_rdisc(act, from, to, ifp, p, len); 915 916 if (ifp == 0) 917 trace_pkt("unknown interface for router-discovery %s" 918 " from %s to %s", 919 type, naddr_ntoa(from), naddr_ntoa(to)); 920 921 return ifp; 922 } 923 924 925 /* read packets from the router discovery socket 926 */ 927 void 928 read_d(void) 929 { 930 static naddr bad_asize, bad_len; 931 struct sockaddr_in from; 932 int n, fromlen, cc, hlen; 933 union { 934 struct ip ip; 935 u_short s[512/2]; 936 u_char b[512]; 937 } pkt; 938 union ad_u *p; 939 n_long *wp; 940 struct interface *ifp; 941 942 943 for (;;) { 944 fromlen = sizeof(from); 945 cc = recvfrom(rdisc_sock, &pkt, sizeof(pkt), 0, 946 (struct sockaddr*)&from, 947 &fromlen); 948 if (cc <= 0) { 949 if (cc < 0 && errno != EWOULDBLOCK) 950 LOGERR("recvfrom(rdisc_sock)"); 951 break; 952 } 953 if (fromlen != sizeof(struct sockaddr_in)) 954 logbad(1,"impossible recvfrom(rdisc_sock) fromlen=%d", 955 fromlen); 956 957 hlen = pkt.ip.ip_hl << 2; 958 if (cc < hlen + ICMP_MINLEN) 959 continue; 960 p = (union ad_u *)&pkt.b[hlen]; 961 cc -= hlen; 962 963 ifp = ck_icmp("Recv", 964 from.sin_addr.s_addr, pkt.ip.ip_dst.s_addr, 965 p, cc); 966 if (ifp == 0) 967 continue; 968 if (ifwithaddr(from.sin_addr.s_addr, 0, 0)) { 969 trace_pkt("\tdiscard our own Router Discovery msg\n"); 970 continue; 971 } 972 973 switch (p->icmp.icmp_type) { 974 case ICMP_ROUTERADVERT: 975 if (p->ad.icmp_ad_asize*4 976 < sizeof(p->ad.icmp_ad_info[0])) { 977 if (bad_asize != from.sin_addr.s_addr) { 978 msglog("intolerable rdisc address" 979 " size=%d", 980 p->ad.icmp_ad_asize); 981 bad_asize = from.sin_addr.s_addr; 982 } 983 continue; 984 } 985 if (p->ad.icmp_ad_num == 0) { 986 trace_pkt("\tempty?\n"); 987 continue; 988 } 989 if (cc != (sizeof(p->ad) - sizeof(p->ad.icmp_ad_info) 990 + (p->ad.icmp_ad_num 991 * sizeof(p->ad.icmp_ad_info[0])))) { 992 if (bad_len != from.sin_addr.s_addr) { 993 msglog("rdisc length %d does not" 994 " match ad_num %d", 995 cc, p->ad.icmp_ad_num); 996 bad_len = from.sin_addr.s_addr; 997 } 998 continue; 999 } 1000 if (supplier) 1001 continue; 1002 if (ifp->int_state & IS_NO_ADV_IN) 1003 continue; 1004 1005 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr; 1006 for (n = 0; n < p->ad.icmp_ad_num; n++) { 1007 parse_ad(from.sin_addr.s_addr, 1008 wp[0], wp[1], 1009 ntohs(p->ad.icmp_ad_life), 1010 ifp); 1011 wp += p->ad.icmp_ad_asize; 1012 } 1013 break; 1014 1015 1016 case ICMP_ROUTERSOLICIT: 1017 if (!supplier) 1018 continue; 1019 if (ifp->int_state & IS_NO_ADV_OUT) 1020 continue; 1021 1022 /* XXX 1023 * We should handle messages from address 0. 1024 */ 1025 1026 /* Respond with a point-to-point advertisement */ 1027 send_adv(ifp, from.sin_addr.s_addr, 0); 1028 break; 1029 } 1030 } 1031 1032 rdisc_sort(); 1033 } 1034