rdisc.c revision 1.1.1.4
1 /* 2 * Copyright (c) 1995 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 acknowledgement: 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 34 #if !defined(lint) && !defined(sgi) && !defined(__NetBSD__) 35 static char sccsid[] = "@(#)rdisc.c 8.1 (Berkeley) x/y/95"; 36 #elif defined(__NetBSD__) 37 static char rcsid[] = "$NetBSD: rdisc.c,v 1.1.1.4 1998/06/02 17:41:26 thorpej Exp $"; 38 #endif 39 #ident "$Revision: 1.1.1.4 $" 40 41 #include "defs.h" 42 #include <netinet/in_systm.h> 43 #include <netinet/ip.h> 44 #include <netinet/ip_icmp.h> 45 #if defined(sgi) && !defined(PRE_KUDZU) 46 #include <cap_net.h> 47 #else 48 #define cap_socket socket 49 #endif 50 51 /* router advertisement ICMP packet */ 52 struct icmp_ad { 53 u_int8_t icmp_type; /* type of message */ 54 u_int8_t icmp_code; /* type sub code */ 55 u_int16_t icmp_cksum; /* ones complement cksum of struct */ 56 u_int8_t icmp_ad_num; /* # of following router addresses */ 57 u_int8_t icmp_ad_asize; /* 2--words in each advertisement */ 58 u_int16_t icmp_ad_life; /* seconds of validity */ 59 struct icmp_ad_info { 60 n_long icmp_ad_addr; 61 n_long icmp_ad_pref; 62 } icmp_ad_info[1]; 63 }; 64 65 /* router solicitation ICMP packet */ 66 struct icmp_so { 67 u_int8_t icmp_type; /* type of message */ 68 u_int8_t icmp_code; /* type sub code */ 69 u_int16_t icmp_cksum; /* ones complement cksum of struct */ 70 n_long icmp_so_rsvd; 71 }; 72 73 union ad_u { 74 struct icmp icmp; 75 struct icmp_ad ad; 76 struct icmp_so so; 77 }; 78 79 80 int rdisc_sock = -1; /* router-discovery raw socket */ 81 struct interface *rdisc_sock_mcast; /* current multicast interface */ 82 83 struct timeval rdisc_timer; 84 int rdisc_ok; /* using solicted route */ 85 86 87 #define MAX_ADS 16 /* at least one per interface */ 88 struct dr { /* accumulated advertisements */ 89 struct interface *dr_ifp; 90 naddr dr_gate; /* gateway */ 91 time_t dr_ts; /* when received */ 92 time_t dr_life; /* lifetime */ 93 n_long dr_recv_pref; /* received but biased preference */ 94 n_long dr_pref; /* preference adjusted by metric */ 95 } *cur_drp, drs[MAX_ADS]; 96 97 /* convert between signed, balanced around zero, 98 * and unsigned zero-based preferences */ 99 #define SIGN_PREF(p) ((p) ^ MIN_PreferenceLevel) 100 #define UNSIGN_PREF(p) SIGN_PREF(p) 101 /* adjust unsigned preference by interface metric, 102 * without driving it to infinity */ 103 #define PREF(p, ifp) ((p) <= (ifp)->int_metric ? ((p) != 0 ? 1 : 0) \ 104 : (p) - ((ifp)->int_metric)) 105 106 static void rdisc_sort(void); 107 108 109 /* dump an ICMP Router Discovery Advertisement Message 110 */ 111 static void 112 trace_rdisc(char *act, 113 naddr from, 114 naddr to, 115 struct interface *ifp, 116 union ad_u *p, 117 u_int len) 118 { 119 int i; 120 n_long *wp, *lim; 121 122 123 if (!TRACEPACKETS || ftrace == 0) 124 return; 125 126 lastlog(); 127 128 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) { 129 (void)fprintf(ftrace, "%s Router Ad" 130 " from %s to %s via %s life=%d\n", 131 act, naddr_ntoa(from), naddr_ntoa(to), 132 ifp ? ifp->int_name : "?", 133 ntohs(p->ad.icmp_ad_life)); 134 if (!TRACECONTENTS) 135 return; 136 137 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr; 138 lim = &wp[(len - sizeof(p->ad)) / sizeof(*wp)]; 139 for (i = 0; i < p->ad.icmp_ad_num && wp <= lim; i++) { 140 (void)fprintf(ftrace, "\t%s preference=%d", 141 naddr_ntoa(wp[0]), (int)ntohl(wp[1])); 142 wp += p->ad.icmp_ad_asize; 143 } 144 (void)fputc('\n',ftrace); 145 146 } else { 147 trace_act("%s Router Solic. from %s to %s via %s value=%#x", 148 act, naddr_ntoa(from), naddr_ntoa(to), 149 ifp ? ifp->int_name : "?", 150 ntohl(p->so.icmp_so_rsvd)); 151 } 152 } 153 154 /* prepare Router Discovery socket. 155 */ 156 static void 157 get_rdisc_sock(void) 158 { 159 if (rdisc_sock < 0) { 160 rdisc_sock = cap_socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); 161 if (rdisc_sock < 0) 162 BADERR(1,"rdisc_sock = socket()"); 163 fix_sock(rdisc_sock,"rdisc_sock"); 164 fix_select(); 165 } 166 } 167 168 169 /* Pick multicast group for router-discovery socket 170 */ 171 void 172 set_rdisc_mg(struct interface *ifp, 173 int on) /* 0=turn it off */ 174 { 175 struct ip_mreq m; 176 177 if (rdisc_sock < 0) { 178 /* Create the raw socket so that we can hear at least 179 * broadcast router discovery packets. 180 */ 181 if ((ifp->int_state & IS_NO_RDISC) == IS_NO_RDISC 182 || !on) 183 return; 184 get_rdisc_sock(); 185 } 186 187 if (!(ifp->int_if_flags & IFF_MULTICAST)) { 188 ifp->int_state &= ~(IS_ALL_HOSTS | IS_ALL_ROUTERS); 189 return; 190 } 191 192 #ifdef MCAST_PPP_BUG 193 if (ifp->int_if_flags & IFF_POINTOPOINT) 194 return; 195 #endif 196 bzero(&m, sizeof(m)); 197 m.imr_interface.s_addr = ((ifp->int_if_flags & IFF_POINTOPOINT) 198 ? ifp->int_dstaddr 199 : ifp->int_addr); 200 if (supplier 201 || (ifp->int_state & IS_NO_ADV_IN) 202 || !on) { 203 /* stop listening to advertisements 204 */ 205 if (ifp->int_state & IS_ALL_HOSTS) { 206 m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP); 207 if (setsockopt(rdisc_sock, IPPROTO_IP, 208 IP_DROP_MEMBERSHIP, 209 &m, sizeof(m)) < 0) 210 LOGERR("IP_DROP_MEMBERSHIP ALLHOSTS"); 211 ifp->int_state &= ~IS_ALL_HOSTS; 212 } 213 214 } else if (!(ifp->int_state & IS_ALL_HOSTS)) { 215 /* start listening to advertisements 216 */ 217 m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP); 218 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, 219 &m, sizeof(m)) < 0) { 220 LOGERR("IP_ADD_MEMBERSHIP ALLHOSTS"); 221 } else { 222 ifp->int_state |= IS_ALL_HOSTS; 223 } 224 } 225 226 if (!supplier 227 || (ifp->int_state & IS_NO_ADV_OUT) 228 || !on) { 229 /* stop listening to solicitations 230 */ 231 if (ifp->int_state & IS_ALL_ROUTERS) { 232 m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP); 233 if (setsockopt(rdisc_sock, IPPROTO_IP, 234 IP_DROP_MEMBERSHIP, 235 &m, sizeof(m)) < 0) 236 LOGERR("IP_DROP_MEMBERSHIP ALLROUTERS"); 237 ifp->int_state &= ~IS_ALL_ROUTERS; 238 } 239 240 } else if (!(ifp->int_state & IS_ALL_ROUTERS)) { 241 /* start hearing solicitations 242 */ 243 m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP); 244 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, 245 &m, sizeof(m)) < 0) { 246 LOGERR("IP_ADD_MEMBERSHIP ALLROUTERS"); 247 } else { 248 ifp->int_state |= IS_ALL_ROUTERS; 249 } 250 } 251 } 252 253 254 /* start supplying routes 255 */ 256 void 257 set_supplier(void) 258 { 259 struct interface *ifp; 260 struct dr *drp; 261 262 if (supplier_set) 263 return; 264 265 trace_act("start suppying routes"); 266 267 /* Forget discovered routes. 268 */ 269 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 270 drp->dr_recv_pref = 0; 271 drp->dr_life = 0; 272 } 273 rdisc_age(0); 274 275 supplier_set = 1; 276 supplier = 1; 277 278 /* Do not start advertising until we have heard some RIP routes */ 279 LIM_SEC(rdisc_timer, now.tv_sec+MIN_WAITTIME); 280 281 /* Switch router discovery multicast groups from soliciting 282 * to advertising. 283 */ 284 for (ifp = ifnet; ifp; ifp = ifp->int_next) { 285 if (ifp->int_state & IS_BROKE) 286 continue; 287 ifp->int_rdisc_cnt = 0; 288 ifp->int_rdisc_timer.tv_usec = rdisc_timer.tv_usec; 289 ifp->int_rdisc_timer.tv_sec = now.tv_sec+MIN_WAITTIME; 290 set_rdisc_mg(ifp, 1); 291 } 292 293 /* get rid of any redirects */ 294 del_redirects(0,0); 295 } 296 297 298 /* age discovered routes and find the best one 299 */ 300 void 301 rdisc_age(naddr bad_gate) 302 { 303 time_t sec; 304 struct dr *drp; 305 306 307 /* If only adverising, then do only that. */ 308 if (supplier) { 309 /* If switching from client to server, get rid of old 310 * default routes. 311 */ 312 if (cur_drp != 0) 313 rdisc_sort(); 314 rdisc_adv(); 315 return; 316 } 317 318 /* If we are being told about a bad router, 319 * then age the discovered default route, and if there is 320 * no alternative, solicite a replacement. 321 */ 322 if (bad_gate != 0) { 323 /* Look for the bad discovered default route. 324 * Age it and note its interface. 325 */ 326 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 327 if (drp->dr_ts == 0) 328 continue; 329 330 /* When we find the bad router, then age the route 331 * to at most SUPPLY_INTERVAL. 332 * This is contrary to RFC 1256, but defends against 333 * black holes. 334 */ 335 if (drp->dr_gate == bad_gate) { 336 sec = (now.tv_sec - drp->dr_life 337 + SUPPLY_INTERVAL); 338 if (drp->dr_ts > sec) { 339 trace_act("age 0.0.0.0 --> %s via %s", 340 naddr_ntoa(drp->dr_gate), 341 drp->dr_ifp->int_name); 342 drp->dr_ts = sec; 343 } 344 break; 345 } 346 } 347 } 348 349 rdisc_sol(); 350 rdisc_sort(); 351 352 /* Delete old redirected routes to keep the kernel table small, 353 * and to prevent black holes. Check that the kernel table 354 * matches the daemon table (i.e. has the default route). 355 * But only if RIP is not running and we are not dealing with 356 * a bad gateway, since otherwise age() will be called. 357 */ 358 if (rip_sock < 0 && bad_gate == 0) 359 age(0); 360 } 361 362 363 /* Zap all routes discovered via an interface that has gone bad 364 * This should only be called when !(ifp->int_state & IS_ALIAS) 365 */ 366 void 367 if_bad_rdisc(struct interface *ifp) 368 { 369 struct dr *drp; 370 371 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 372 if (drp->dr_ifp != ifp) 373 continue; 374 drp->dr_recv_pref = 0; 375 drp->dr_ts = 0; 376 drp->dr_life = 0; 377 } 378 379 /* make a note to re-solicit, turn RIP on or off, etc. */ 380 rdisc_timer.tv_sec = 0; 381 } 382 383 384 /* mark an interface ok for router discovering. 385 */ 386 void 387 if_ok_rdisc(struct interface *ifp) 388 { 389 set_rdisc_mg(ifp, 1); 390 391 ifp->int_rdisc_cnt = 0; 392 ifp->int_rdisc_timer.tv_sec = now.tv_sec + (supplier 393 ? MIN_WAITTIME 394 : MAX_SOLICITATION_DELAY); 395 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 396 rdisc_timer = ifp->int_rdisc_timer; 397 } 398 399 400 /* get rid of a dead discovered router 401 */ 402 static void 403 del_rdisc(struct dr *drp) 404 { 405 struct interface *ifp; 406 naddr gate; 407 int i; 408 409 410 del_redirects(gate = drp->dr_gate, 0); 411 drp->dr_ts = 0; 412 drp->dr_life = 0; 413 414 415 /* Count the other discovered routes on the interface. 416 */ 417 i = 0; 418 ifp = drp->dr_ifp; 419 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 420 if (drp->dr_ts != 0 421 && drp->dr_ifp == ifp) 422 i++; 423 } 424 425 /* If that was the last good discovered router on the interface, 426 * then solicit a new one. 427 * This is contrary to RFC 1256, but defends against black holes. 428 */ 429 if (i != 0) { 430 trace_act("discovered router %s via %s" 431 " is bad--have %d remaining", 432 naddr_ntoa(gate), ifp->int_name, i); 433 } else if (ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) { 434 trace_act("last discovered router %s via %s" 435 " is bad--re-solicit", 436 naddr_ntoa(gate), ifp->int_name); 437 ifp->int_rdisc_cnt = 0; 438 ifp->int_rdisc_timer.tv_sec = 0; 439 rdisc_sol(); 440 } else { 441 trace_act("last discovered router %s via %s" 442 " is bad--wait to solicit", 443 naddr_ntoa(gate), ifp->int_name); 444 } 445 } 446 447 448 /* Find the best discovered route, 449 * and discard stale routers. 450 */ 451 static void 452 rdisc_sort(void) 453 { 454 struct dr *drp, *new_drp; 455 struct rt_entry *rt; 456 struct rt_spare new; 457 struct interface *ifp; 458 u_int new_st; 459 n_long new_pref; 460 461 462 /* Find the best discovered route. 463 */ 464 new_drp = 0; 465 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 466 if (drp->dr_ts == 0) 467 continue; 468 ifp = drp->dr_ifp; 469 470 /* Get rid of expired discovered routers. 471 */ 472 if (drp->dr_ts + drp->dr_life <= now.tv_sec) { 473 del_rdisc(drp); 474 continue; 475 } 476 477 LIM_SEC(rdisc_timer, drp->dr_ts+drp->dr_life+1); 478 479 /* Update preference with possibly changed interface 480 * metric. 481 */ 482 drp->dr_pref = PREF(drp->dr_recv_pref, ifp); 483 484 /* Prefer the current route to prevent thrashing. 485 * Prefer shorter lifetimes to speed the detection of 486 * bad routers. 487 * Avoid sick interfaces. 488 */ 489 if (new_drp == 0 490 || (!((new_st ^ drp->dr_ifp->int_state) & IS_SICK) 491 && (new_pref < drp->dr_pref 492 || (new_pref == drp->dr_pref 493 && (drp == cur_drp 494 || (new_drp != cur_drp 495 && new_drp->dr_life > drp->dr_life))))) 496 || ((new_st & IS_SICK) 497 && !(drp->dr_ifp->int_state & IS_SICK))) { 498 new_drp = drp; 499 new_st = drp->dr_ifp->int_state; 500 new_pref = drp->dr_pref; 501 } 502 } 503 504 /* switch to a better default route 505 */ 506 if (new_drp != cur_drp) { 507 rt = rtget(RIP_DEFAULT, 0); 508 509 /* Stop using discovered routes if they are all bad 510 */ 511 if (new_drp == 0) { 512 trace_act("turn off Router Discovery client"); 513 rdisc_ok = 0; 514 515 if (rt != 0 516 && (rt->rt_state & RS_RDISC)) { 517 new = rt->rt_spares[0]; 518 new.rts_metric = HOPCNT_INFINITY; 519 new.rts_time = now.tv_sec - GARBAGE_TIME; 520 rtchange(rt, rt->rt_state & ~RS_RDISC, 521 &new, 0); 522 rtswitch(rt, 0); 523 } 524 525 } else { 526 if (cur_drp == 0) { 527 trace_act("turn on Router Discovery client" 528 " using %s via %s", 529 naddr_ntoa(new_drp->dr_gate), 530 new_drp->dr_ifp->int_name); 531 rdisc_ok = 1; 532 533 } else { 534 trace_act("switch Router Discovery from" 535 " %s via %s to %s via %s", 536 naddr_ntoa(cur_drp->dr_gate), 537 cur_drp->dr_ifp->int_name, 538 naddr_ntoa(new_drp->dr_gate), 539 new_drp->dr_ifp->int_name); 540 } 541 542 bzero(&new, sizeof(new)); 543 new.rts_ifp = new_drp->dr_ifp; 544 new.rts_gate = new_drp->dr_gate; 545 new.rts_router = new_drp->dr_gate; 546 new.rts_metric = HOPCNT_INFINITY-1; 547 new.rts_time = now.tv_sec; 548 if (rt != 0) { 549 rtchange(rt, rt->rt_state | RS_RDISC, &new, 0); 550 } else { 551 rtadd(RIP_DEFAULT, 0, RS_RDISC, &new); 552 } 553 } 554 555 cur_drp = new_drp; 556 } 557 558 /* turn RIP on or off */ 559 if (!rdisc_ok || rip_interfaces > 1) { 560 rip_on(0); 561 } else { 562 rip_off(); 563 } 564 } 565 566 567 /* handle a single address in an advertisement 568 */ 569 static void 570 parse_ad(naddr from, 571 naddr gate, 572 n_long pref, /* signed and in network order */ 573 u_short life, 574 struct interface *ifp) 575 { 576 static struct msg_limit bad_gate; 577 struct dr *drp, *new_drp; 578 579 580 if (gate == RIP_DEFAULT 581 || !check_dst(gate)) { 582 msglim(&bad_gate, from,"router %s advertising bad gateway %s", 583 naddr_ntoa(from), 584 naddr_ntoa(gate)); 585 return; 586 } 587 588 /* ignore pointers to ourself and routes via unreachable networks 589 */ 590 if (ifwithaddr(gate, 1, 0) != 0) { 591 trace_pkt(" discard Router Discovery Ad pointing at us"); 592 return; 593 } 594 if (!on_net(gate, ifp->int_net, ifp->int_mask)) { 595 trace_pkt(" discard Router Discovery Ad" 596 " toward unreachable net"); 597 return; 598 } 599 600 /* Convert preference to an unsigned value 601 * and later bias it by the metric of the interface. 602 */ 603 pref = UNSIGN_PREF(ntohl(pref)); 604 605 if (pref == 0 || life < MinMaxAdvertiseInterval) { 606 pref = 0; 607 life = 0; 608 } 609 610 for (new_drp = 0, drp = drs; drp < &drs[MAX_ADS]; drp++) { 611 /* accept new info for a familiar entry 612 */ 613 if (drp->dr_gate == gate) { 614 new_drp = drp; 615 break; 616 } 617 618 if (life == 0) 619 continue; /* do not worry about dead ads */ 620 621 if (drp->dr_ts == 0) { 622 new_drp = drp; /* use unused entry */ 623 624 } else if (new_drp == 0) { 625 /* look for an entry worse than the new one to 626 * reuse. 627 */ 628 if ((!(ifp->int_state & IS_SICK) 629 && (drp->dr_ifp->int_state & IS_SICK)) 630 || (pref > drp->dr_pref 631 && !((ifp->int_state ^ drp->dr_ifp->int_state) 632 & IS_SICK))) 633 new_drp = drp; 634 635 } else if (new_drp->dr_ts != 0) { 636 /* look for the least valueable entry to reuse 637 */ 638 if ((!(new_drp->dr_ifp->int_state & IS_SICK) 639 && (drp->dr_ifp->int_state & IS_SICK)) 640 || (new_drp->dr_pref > drp->dr_pref 641 && !((new_drp->dr_ifp->int_state 642 ^ drp->dr_ifp->int_state) 643 & IS_SICK))) 644 new_drp = drp; 645 } 646 } 647 648 /* forget it if all of the current entries are better */ 649 if (new_drp == 0) 650 return; 651 652 new_drp->dr_ifp = ifp; 653 new_drp->dr_gate = gate; 654 new_drp->dr_ts = now.tv_sec; 655 new_drp->dr_life = ntohs(life); 656 new_drp->dr_recv_pref = pref; 657 /* bias functional preference by metric of the interface */ 658 new_drp->dr_pref = PREF(pref,ifp); 659 660 /* after hearing a good advertisement, stop asking 661 */ 662 if (!(ifp->int_state & IS_SICK)) 663 ifp->int_rdisc_cnt = MAX_SOLICITATIONS; 664 } 665 666 667 /* Compute the IP checksum 668 * This assumes the packet is less than 32K long. 669 */ 670 static u_short 671 in_cksum(u_short *p, 672 u_int len) 673 { 674 u_int sum = 0; 675 int nwords = len >> 1; 676 677 while (nwords-- != 0) 678 sum += *p++; 679 680 if (len & 1) 681 sum += *(u_char *)p; 682 683 /* end-around-carry */ 684 sum = (sum >> 16) + (sum & 0xffff); 685 sum += (sum >> 16); 686 return (~sum); 687 } 688 689 690 /* Send a router discovery advertisement or solicitation ICMP packet. 691 */ 692 static void 693 send_rdisc(union ad_u *p, 694 int p_size, 695 struct interface *ifp, 696 naddr dst, /* 0 or unicast destination */ 697 int type) /* 0=unicast, 1=bcast, 2=mcast */ 698 { 699 struct sockaddr_in sin; 700 int flags; 701 char *msg; 702 naddr tgt_mcast; 703 704 705 bzero(&sin, sizeof(sin)); 706 sin.sin_addr.s_addr = dst; 707 sin.sin_family = AF_INET; 708 #ifdef _HAVE_SIN_LEN 709 sin.sin_len = sizeof(sin); 710 #endif 711 flags = MSG_DONTROUTE; 712 713 switch (type) { 714 case 0: /* unicast */ 715 default: 716 msg = "Send"; 717 break; 718 719 case 1: /* broadcast */ 720 if (ifp->int_if_flags & IFF_POINTOPOINT) { 721 msg = "Send pt-to-pt"; 722 sin.sin_addr.s_addr = ifp->int_dstaddr; 723 } else { 724 msg = "Send broadcast"; 725 sin.sin_addr.s_addr = ifp->int_brdaddr; 726 } 727 break; 728 729 case 2: /* multicast */ 730 msg = "Send multicast"; 731 if (ifp->int_state & IS_DUP) { 732 trace_act("abort multicast output via %s" 733 " with duplicate address", 734 ifp->int_name); 735 return; 736 } 737 if (rdisc_sock_mcast != ifp) { 738 /* select the right interface. */ 739 #ifdef MCAST_PPP_BUG 740 /* Do not specifiy the primary interface explicitly 741 * if we have the multicast point-to-point kernel 742 * bug, since the kernel will do the wrong thing 743 * if the local address of a point-to-point link 744 * is the same as the address of an ordinary 745 * interface. 746 */ 747 if (ifp->int_addr == myaddr) { 748 tgt_mcast = 0; 749 } else 750 #endif 751 tgt_mcast = ifp->int_addr; 752 if (0 > setsockopt(rdisc_sock, 753 IPPROTO_IP, IP_MULTICAST_IF, 754 &tgt_mcast, sizeof(tgt_mcast))) { 755 LOGERR("setsockopt(rdisc_sock," 756 "IP_MULTICAST_IF)"); 757 rdisc_sock_mcast = 0; 758 return; 759 } 760 rdisc_sock_mcast = ifp; 761 } 762 flags = 0; 763 break; 764 } 765 766 if (rdisc_sock < 0) 767 get_rdisc_sock(); 768 769 trace_rdisc(msg, ifp->int_addr, sin.sin_addr.s_addr, ifp, 770 p, p_size); 771 772 if (0 > sendto(rdisc_sock, p, p_size, flags, 773 (struct sockaddr *)&sin, sizeof(sin))) { 774 if (ifp == 0 || !(ifp->int_state & IS_BROKE)) 775 msglog("sendto(%s%s%s): %s", 776 ifp != 0 ? ifp->int_name : "", 777 ifp != 0 ? ", " : "", 778 inet_ntoa(sin.sin_addr), 779 strerror(errno)); 780 if (ifp != 0) 781 if_sick(ifp); 782 } 783 } 784 785 786 /* Send an advertisement 787 */ 788 static void 789 send_adv(struct interface *ifp, 790 naddr dst, /* 0 or unicast destination */ 791 int type) /* 0=unicast, 1=bcast, 2=mcast */ 792 { 793 union ad_u u; 794 n_long pref; 795 796 797 bzero(&u,sizeof(u.ad)); 798 799 u.ad.icmp_type = ICMP_ROUTERADVERT; 800 u.ad.icmp_ad_num = 1; 801 u.ad.icmp_ad_asize = sizeof(u.ad.icmp_ad_info[0])/4; 802 803 u.ad.icmp_ad_life = stopint ? 0 : htons(ifp->int_rdisc_int*3); 804 805 /* Convert the configured preference to an unsigned value, 806 * bias it by the interface metric, and then send it as a 807 * signed, network byte order value. 808 */ 809 pref = UNSIGN_PREF(ifp->int_rdisc_pref); 810 u.ad.icmp_ad_info[0].icmp_ad_pref = htonl(SIGN_PREF(PREF(pref, ifp))); 811 812 u.ad.icmp_ad_info[0].icmp_ad_addr = ifp->int_addr; 813 814 u.ad.icmp_cksum = in_cksum((u_short*)&u.ad, sizeof(u.ad)); 815 816 send_rdisc(&u, sizeof(u.ad), ifp, dst, type); 817 } 818 819 820 /* Advertise for Router Discovery 821 */ 822 void 823 rdisc_adv(void) 824 { 825 struct interface *ifp; 826 827 if (!supplier) 828 return; 829 830 rdisc_timer.tv_sec = now.tv_sec + NEVER; 831 832 for (ifp = ifnet; ifp; ifp = ifp->int_next) { 833 if (0 != (ifp->int_state & (IS_NO_ADV_OUT | IS_BROKE))) 834 continue; 835 836 if (!timercmp(&ifp->int_rdisc_timer, &now, >) 837 || stopint) { 838 send_adv(ifp, htonl(INADDR_ALLHOSTS_GROUP), 839 (ifp->int_state&IS_BCAST_RDISC) ? 1 : 2); 840 ifp->int_rdisc_cnt++; 841 842 intvl_random(&ifp->int_rdisc_timer, 843 (ifp->int_rdisc_int*3)/4, 844 ifp->int_rdisc_int); 845 if (ifp->int_rdisc_cnt < MAX_INITIAL_ADVERTS 846 && (ifp->int_rdisc_timer.tv_sec 847 > MAX_INITIAL_ADVERT_INTERVAL)) { 848 ifp->int_rdisc_timer.tv_sec 849 = MAX_INITIAL_ADVERT_INTERVAL; 850 } 851 timevaladd(&ifp->int_rdisc_timer, &now); 852 } 853 854 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 855 rdisc_timer = ifp->int_rdisc_timer; 856 } 857 } 858 859 860 /* Solicit for Router Discovery 861 */ 862 void 863 rdisc_sol(void) 864 { 865 struct interface *ifp; 866 union ad_u u; 867 868 869 if (supplier) 870 return; 871 872 rdisc_timer.tv_sec = now.tv_sec + NEVER; 873 874 for (ifp = ifnet; ifp; ifp = ifp->int_next) { 875 if (0 != (ifp->int_state & (IS_NO_SOL_OUT | IS_BROKE)) 876 || ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) 877 continue; 878 879 if (!timercmp(&ifp->int_rdisc_timer, &now, >)) { 880 bzero(&u,sizeof(u.so)); 881 u.so.icmp_type = ICMP_ROUTERSOLICIT; 882 u.so.icmp_cksum = in_cksum((u_short*)&u.so, 883 sizeof(u.so)); 884 send_rdisc(&u, sizeof(u.so), ifp, 885 htonl(INADDR_ALLROUTERS_GROUP), 886 ((ifp->int_state&IS_BCAST_RDISC) ? 1 : 2)); 887 888 if (++ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) 889 continue; 890 891 ifp->int_rdisc_timer.tv_sec = SOLICITATION_INTERVAL; 892 ifp->int_rdisc_timer.tv_usec = 0; 893 timevaladd(&ifp->int_rdisc_timer, &now); 894 } 895 896 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 897 rdisc_timer = ifp->int_rdisc_timer; 898 } 899 } 900 901 902 /* check the IP header of a possible Router Discovery ICMP packet */ 903 static struct interface * /* 0 if bad */ 904 ck_icmp(char *act, 905 naddr from, 906 struct interface *ifp, 907 naddr to, 908 union ad_u *p, 909 u_int len) 910 { 911 char *type; 912 913 914 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) { 915 type = "advertisement"; 916 } else if (p->icmp.icmp_type == ICMP_ROUTERSOLICIT) { 917 type = "solicitation"; 918 } else { 919 return 0; 920 } 921 922 if (p->icmp.icmp_code != 0) { 923 trace_pkt("unrecognized ICMP Router %s code=%d from %s to %s", 924 type, p->icmp.icmp_code, 925 naddr_ntoa(from), naddr_ntoa(to)); 926 return 0; 927 } 928 929 trace_rdisc(act, from, to, ifp, p, len); 930 931 if (ifp == 0) 932 trace_pkt("unknown interface for router-discovery %s" 933 " from %s to %s", 934 type, naddr_ntoa(from), naddr_ntoa(to)); 935 936 return ifp; 937 } 938 939 940 /* read packets from the router discovery socket 941 */ 942 void 943 read_d(void) 944 { 945 static struct msg_limit bad_asize, bad_len; 946 #ifdef USE_PASSIFNAME 947 static struct msg_limit bad_name; 948 #endif 949 struct sockaddr_in from; 950 int n, fromlen, cc, hlen; 951 struct { 952 #ifdef USE_PASSIFNAME 953 char ifname[IFNAMSIZ]; 954 #endif 955 union { 956 struct ip ip; 957 u_short s[512/2]; 958 u_char b[512]; 959 } pkt; 960 } buf; 961 union ad_u *p; 962 n_long *wp; 963 struct interface *ifp; 964 965 966 for (;;) { 967 fromlen = sizeof(from); 968 cc = recvfrom(rdisc_sock, &buf, sizeof(buf), 0, 969 (struct sockaddr*)&from, 970 &fromlen); 971 if (cc <= 0) { 972 if (cc < 0 && errno != EWOULDBLOCK) 973 LOGERR("recvfrom(rdisc_sock)"); 974 break; 975 } 976 if (fromlen != sizeof(struct sockaddr_in)) 977 logbad(1,"impossible recvfrom(rdisc_sock) fromlen=%d", 978 fromlen); 979 #ifdef USE_PASSIFNAME 980 if ((cc -= sizeof(buf.ifname)) < 0) 981 logbad(0,"missing USE_PASSIFNAME; only %d bytes", 982 cc+sizeof(buf.ifname)); 983 #endif 984 985 hlen = buf.pkt.ip.ip_hl << 2; 986 if (cc < hlen + ICMP_MINLEN) 987 continue; 988 p = (union ad_u *)&buf.pkt.b[hlen]; 989 cc -= hlen; 990 991 #ifdef USE_PASSIFNAME 992 ifp = ifwithname(buf.ifname, 0); 993 if (ifp == 0) 994 msglim(&bad_name, from.sin_addr.s_addr, 995 "impossible rdisc if_ name %.*s", 996 IFNAMSIZ, buf.ifname); 997 #else 998 /* If we could tell the interface on which a packet from 999 * address 0 arrived, we could deal with such solicitations. 1000 */ 1001 ifp = ((from.sin_addr.s_addr == 0) 1002 ? 0 : iflookup(from.sin_addr.s_addr)); 1003 #endif 1004 ifp = ck_icmp("Recv", from.sin_addr.s_addr, ifp, 1005 buf.pkt.ip.ip_dst.s_addr, p, cc); 1006 if (ifp == 0) 1007 continue; 1008 if (ifwithaddr(from.sin_addr.s_addr, 0, 0)) { 1009 trace_pkt(" " 1010 "discard our own Router Discovery message"); 1011 continue; 1012 } 1013 1014 switch (p->icmp.icmp_type) { 1015 case ICMP_ROUTERADVERT: 1016 if (p->ad.icmp_ad_asize*4 1017 < sizeof(p->ad.icmp_ad_info[0])) { 1018 msglim(&bad_asize, from.sin_addr.s_addr, 1019 "intolerable rdisc address size=%d", 1020 p->ad.icmp_ad_asize); 1021 continue; 1022 } 1023 if (p->ad.icmp_ad_num == 0) { 1024 trace_pkt(" empty?"); 1025 continue; 1026 } 1027 if (cc != (sizeof(p->ad) - sizeof(p->ad.icmp_ad_info) 1028 + (p->ad.icmp_ad_num 1029 * sizeof(p->ad.icmp_ad_info[0])))) { 1030 msglim(&bad_len, from.sin_addr.s_addr, 1031 "rdisc length %d does not match ad_num" 1032 " %d", cc, p->ad.icmp_ad_num); 1033 continue; 1034 } 1035 if (supplier) 1036 continue; 1037 if (ifp->int_state & IS_NO_ADV_IN) 1038 continue; 1039 1040 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr; 1041 for (n = 0; n < p->ad.icmp_ad_num; n++) { 1042 parse_ad(from.sin_addr.s_addr, 1043 wp[0], wp[1], 1044 ntohs(p->ad.icmp_ad_life), 1045 ifp); 1046 wp += p->ad.icmp_ad_asize; 1047 } 1048 break; 1049 1050 1051 case ICMP_ROUTERSOLICIT: 1052 if (!supplier) 1053 continue; 1054 if (ifp->int_state & IS_NO_ADV_OUT) 1055 continue; 1056 if (stopint) 1057 continue; 1058 1059 /* XXX 1060 * We should handle messages from address 0. 1061 */ 1062 1063 /* Respond with a point-to-point advertisement */ 1064 send_adv(ifp, from.sin_addr.s_addr, 0); 1065 break; 1066 } 1067 } 1068 1069 rdisc_sort(); 1070 } 1071
Indexes created Thu Oct 23 22:10:10 GMT 2025