rdisc.c revision 1.11
1 /* $NetBSD: rdisc.c,v 1.11 2001/01/15 13:19:12 itojun 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 acknowledgment: 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[] __attribute__((unused)) = "@(#)rdisc.c 8.1 (Berkeley) x/y/95"; 38 #elif defined(__NetBSD__) 39 #include <sys/cdefs.h> 40 __RCSID("$NetBSD: rdisc.c,v 1.11 2001/01/15 13:19:12 itojun Exp $"); 41 #endif 42 43 #include "defs.h" 44 #include <netinet/in_systm.h> 45 #include <netinet/ip.h> 46 #include <netinet/ip_icmp.h> 47 48 /* router advertisement ICMP packet */ 49 struct icmp_ad { 50 u_int8_t icmp_type; /* type of message */ 51 u_int8_t icmp_code; /* type sub code */ 52 u_int16_t icmp_cksum; /* ones complement cksum of struct */ 53 u_int8_t icmp_ad_num; /* # of following router addresses */ 54 u_int8_t icmp_ad_asize; /* 2--words in each advertisement */ 55 u_int16_t icmp_ad_life; /* seconds of validity */ 56 struct icmp_ad_info { 57 n_long icmp_ad_addr; 58 n_long icmp_ad_pref; 59 } icmp_ad_info[1]; 60 }; 61 62 /* router solicitation ICMP packet */ 63 struct icmp_so { 64 u_int8_t icmp_type; /* type of message */ 65 u_int8_t icmp_code; /* type sub code */ 66 u_int16_t icmp_cksum; /* ones complement cksum of struct */ 67 n_long icmp_so_rsvd; 68 }; 69 70 union ad_u { 71 struct icmp icmp; 72 struct icmp_ad ad; 73 struct icmp_so so; 74 }; 75 76 77 int rdisc_sock = -1; /* router-discovery raw socket */ 78 struct interface *rdisc_sock_mcast; /* current multicast interface */ 79 80 struct timeval rdisc_timer; 81 int rdisc_ok; /* using solicited route */ 82 83 84 #define MAX_ADS 16 /* at least one per interface */ 85 struct dr { /* accumulated advertisements */ 86 struct interface *dr_ifp; 87 naddr dr_gate; /* gateway */ 88 time_t dr_ts; /* when received */ 89 time_t dr_life; /* lifetime */ 90 n_long dr_recv_pref; /* received but biased preference */ 91 n_long dr_pref; /* preference adjusted by metric */ 92 } *cur_drp, drs[MAX_ADS]; 93 94 /* convert between signed, balanced around zero, 95 * and unsigned zero-based preferences */ 96 #define SIGN_PREF(p) ((p) ^ MIN_PreferenceLevel) 97 #define UNSIGN_PREF(p) SIGN_PREF(p) 98 /* adjust unsigned preference by interface metric, 99 * without driving it to infinity */ 100 #define PREF(p, ifp) ((int)(p) <= (ifp)->int_metric ? ((p) != 0 ? 1 : 0) \ 101 : (p) - ((ifp)->int_metric)) 102 103 static void rdisc_sort(void); 104 105 106 /* dump an ICMP Router Discovery Advertisement Message 107 */ 108 static void 109 trace_rdisc(const char *act, 110 naddr from, 111 naddr to, 112 struct interface *ifp, 113 union ad_u *p, 114 u_int len) 115 { 116 int i; 117 n_long *wp, *lim; 118 119 120 if (!TRACEPACKETS || ftrace == 0) 121 return; 122 123 lastlog(); 124 125 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) { 126 (void)fprintf(ftrace, "%s Router Ad" 127 " from %s to %s via %s life=%d\n", 128 act, naddr_ntoa(from), naddr_ntoa(to), 129 ifp ? ifp->int_name : "?", 130 ntohs(p->ad.icmp_ad_life)); 131 if (!TRACECONTENTS) 132 return; 133 134 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr; 135 lim = &wp[(len - sizeof(p->ad)) / sizeof(*wp)]; 136 for (i = 0; i < p->ad.icmp_ad_num && wp <= lim; i++) { 137 (void)fprintf(ftrace, "\t%s preference=%d", 138 naddr_ntoa(wp[0]), (int)ntohl(wp[1])); 139 wp += p->ad.icmp_ad_asize; 140 } 141 (void)fputc('\n',ftrace); 142 143 } else { 144 trace_act("%s Router Solic. from %s to %s via %s value=%#x", 145 act, naddr_ntoa(from), naddr_ntoa(to), 146 ifp ? ifp->int_name : "?", 147 (int)ntohl(p->so.icmp_so_rsvd)); 148 } 149 } 150 151 /* prepare Router Discovery socket. 152 */ 153 static void 154 get_rdisc_sock(void) 155 { 156 if (rdisc_sock < 0) { 157 rdisc_sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); 158 if (rdisc_sock < 0) 159 BADERR(1,"rdisc_sock = socket()"); 160 fix_sock(rdisc_sock,"rdisc_sock"); 161 fix_select(); 162 } 163 } 164 165 166 /* Pick multicast group for router-discovery socket 167 */ 168 void 169 set_rdisc_mg(struct interface *ifp, 170 int on) /* 0=turn it off */ 171 { 172 struct ip_mreq m; 173 174 if (rdisc_sock < 0) { 175 /* Create the raw socket so that we can hear at least 176 * broadcast router discovery packets. 177 */ 178 if ((ifp->int_state & IS_NO_RDISC) == IS_NO_RDISC 179 || !on) 180 return; 181 get_rdisc_sock(); 182 } 183 184 if (!(ifp->int_if_flags & IFF_MULTICAST)) { 185 ifp->int_state &= ~(IS_ALL_HOSTS | IS_ALL_ROUTERS); 186 return; 187 } 188 189 #ifdef MCAST_PPP_BUG 190 if (ifp->int_if_flags & IFF_POINTOPOINT) 191 return; 192 #endif 193 memset(&m, 0, sizeof(m)); 194 #ifdef MCAST_IFINDEX 195 m.imr_interface.s_addr = htonl(ifp->int_index); 196 #else 197 m.imr_interface.s_addr = ((ifp->int_if_flags & IFF_POINTOPOINT) 198 ? ifp->int_dstaddr 199 : ifp->int_addr); 200 #endif 201 if (supplier 202 || (ifp->int_state & IS_NO_ADV_IN) 203 || !on) { 204 /* stop listening to advertisements 205 */ 206 if (ifp->int_state & IS_ALL_HOSTS) { 207 m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP); 208 if (setsockopt(rdisc_sock, IPPROTO_IP, 209 IP_DROP_MEMBERSHIP, 210 &m, sizeof(m)) < 0) 211 LOGERR("IP_DROP_MEMBERSHIP ALLHOSTS"); 212 ifp->int_state &= ~IS_ALL_HOSTS; 213 } 214 215 } else if (!(ifp->int_state & IS_ALL_HOSTS)) { 216 /* start listening to advertisements 217 */ 218 m.imr_multiaddr.s_addr = htonl(INADDR_ALLHOSTS_GROUP); 219 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, 220 &m, sizeof(m)) < 0) { 221 LOGERR("IP_ADD_MEMBERSHIP ALLHOSTS"); 222 } else { 223 ifp->int_state |= IS_ALL_HOSTS; 224 } 225 } 226 227 if (!supplier 228 || (ifp->int_state & IS_NO_ADV_OUT) 229 || !on) { 230 /* stop listening to solicitations 231 */ 232 if (ifp->int_state & IS_ALL_ROUTERS) { 233 m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP); 234 if (setsockopt(rdisc_sock, IPPROTO_IP, 235 IP_DROP_MEMBERSHIP, 236 &m, sizeof(m)) < 0) 237 LOGERR("IP_DROP_MEMBERSHIP ALLROUTERS"); 238 ifp->int_state &= ~IS_ALL_ROUTERS; 239 } 240 241 } else if (!(ifp->int_state & IS_ALL_ROUTERS)) { 242 /* start hearing solicitations 243 */ 244 m.imr_multiaddr.s_addr=htonl(INADDR_ALLROUTERS_GROUP); 245 if (setsockopt(rdisc_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, 246 &m, sizeof(m)) < 0) { 247 LOGERR("IP_ADD_MEMBERSHIP ALLROUTERS"); 248 } else { 249 ifp->int_state |= IS_ALL_ROUTERS; 250 } 251 } 252 } 253 254 255 /* start supplying routes 256 */ 257 void 258 set_supplier(void) 259 { 260 struct interface *ifp; 261 struct dr *drp; 262 263 if (supplier_set) 264 return; 265 266 trace_act("start supplying routes"); 267 268 /* Forget discovered routes. 269 */ 270 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 271 drp->dr_recv_pref = 0; 272 drp->dr_life = 0; 273 } 274 rdisc_age(0); 275 276 supplier_set = 1; 277 supplier = 1; 278 279 /* Do not start advertising until we have heard some RIP routes */ 280 LIM_SEC(rdisc_timer, now.tv_sec+MIN_WAITTIME); 281 282 /* Switch router discovery multicast groups from soliciting 283 * to advertising. 284 */ 285 for (ifp = ifnet; ifp; ifp = ifp->int_next) { 286 if (ifp->int_state & IS_BROKE) 287 continue; 288 ifp->int_rdisc_cnt = 0; 289 ifp->int_rdisc_timer.tv_usec = rdisc_timer.tv_usec; 290 ifp->int_rdisc_timer.tv_sec = now.tv_sec+MIN_WAITTIME; 291 set_rdisc_mg(ifp, 1); 292 } 293 294 /* get rid of any redirects */ 295 del_redirects(0,0); 296 } 297 298 299 /* age discovered routes and find the best one 300 */ 301 void 302 rdisc_age(naddr bad_gate) 303 { 304 time_t sec; 305 struct dr *drp; 306 307 308 /* If only advertising, then do only that. */ 309 if (supplier) { 310 /* If switching from client to server, get rid of old 311 * default routes. 312 */ 313 if (cur_drp != 0) 314 rdisc_sort(); 315 rdisc_adv(); 316 return; 317 } 318 319 /* If we are being told about a bad router, 320 * then age the discovered default route, and if there is 321 * no alternative, solicit a replacement. 322 */ 323 if (bad_gate != 0) { 324 /* Look for the bad discovered default route. 325 * Age it and note its interface. 326 */ 327 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 328 if (drp->dr_ts == 0) 329 continue; 330 331 /* When we find the bad router, then age the route 332 * to at most SUPPLY_INTERVAL. 333 * This is contrary to RFC 1256, but defends against 334 * black holes. 335 */ 336 if (drp->dr_gate == bad_gate) { 337 sec = (now.tv_sec - drp->dr_life 338 + SUPPLY_INTERVAL); 339 if (drp->dr_ts > sec) { 340 trace_act("age 0.0.0.0 --> %s via %s", 341 naddr_ntoa(drp->dr_gate), 342 drp->dr_ifp->int_name); 343 drp->dr_ts = sec; 344 } 345 break; 346 } 347 } 348 } 349 350 rdisc_sol(); 351 rdisc_sort(); 352 353 /* Delete old redirected routes to keep the kernel table small, 354 * and to prevent black holes. Check that the kernel table 355 * matches the daemon table (i.e. has the default route). 356 * But only if RIP is not running and we are not dealing with 357 * a bad gateway, since otherwise age() will be called. 358 */ 359 if (rip_sock < 0 && bad_gate == 0) 360 age(0); 361 } 362 363 364 /* Zap all routes discovered via an interface that has gone bad 365 * This should only be called when !(ifp->int_state & IS_ALIAS) 366 */ 367 void 368 if_bad_rdisc(struct interface *ifp) 369 { 370 struct dr *drp; 371 372 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 373 if (drp->dr_ifp != ifp) 374 continue; 375 drp->dr_recv_pref = 0; 376 drp->dr_ts = 0; 377 drp->dr_life = 0; 378 } 379 380 /* make a note to re-solicit, turn RIP on or off, etc. */ 381 rdisc_timer.tv_sec = 0; 382 } 383 384 385 /* mark an interface ok for router discovering. 386 */ 387 void 388 if_ok_rdisc(struct interface *ifp) 389 { 390 set_rdisc_mg(ifp, 1); 391 392 ifp->int_rdisc_cnt = 0; 393 ifp->int_rdisc_timer.tv_sec = now.tv_sec + (supplier 394 ? MIN_WAITTIME 395 : MAX_SOLICITATION_DELAY); 396 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 397 rdisc_timer = ifp->int_rdisc_timer; 398 } 399 400 401 /* get rid of a dead discovered router 402 */ 403 static void 404 del_rdisc(struct dr *drp) 405 { 406 struct interface *ifp; 407 naddr gate; 408 int i; 409 410 411 del_redirects(gate = drp->dr_gate, 0); 412 drp->dr_ts = 0; 413 drp->dr_life = 0; 414 415 416 /* Count the other discovered routes on the interface. 417 */ 418 i = 0; 419 ifp = drp->dr_ifp; 420 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 421 if (drp->dr_ts != 0 422 && drp->dr_ifp == ifp) 423 i++; 424 } 425 426 /* If that was the last good discovered router on the interface, 427 * then solicit a new one. 428 * This is contrary to RFC 1256, but defends against black holes. 429 */ 430 if (i != 0) { 431 trace_act("discovered router %s via %s" 432 " is bad--have %d remaining", 433 naddr_ntoa(gate), ifp->int_name, i); 434 } else if (ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) { 435 trace_act("last discovered router %s via %s" 436 " is bad--re-solicit", 437 naddr_ntoa(gate), ifp->int_name); 438 ifp->int_rdisc_cnt = 0; 439 ifp->int_rdisc_timer.tv_sec = 0; 440 rdisc_sol(); 441 } else { 442 trace_act("last discovered router %s via %s" 443 " is bad--wait to solicit", 444 naddr_ntoa(gate), ifp->int_name); 445 } 446 } 447 448 449 /* Find the best discovered route, 450 * and discard stale routers. 451 */ 452 static void 453 rdisc_sort(void) 454 { 455 struct dr *drp, *new_drp; 456 struct rt_entry *rt; 457 struct rt_spare new; 458 struct interface *ifp; 459 u_int new_st = 0; 460 n_long new_pref = 0; 461 462 463 /* Find the best discovered route. 464 */ 465 new_drp = 0; 466 for (drp = drs; drp < &drs[MAX_ADS]; drp++) { 467 if (drp->dr_ts == 0) 468 continue; 469 ifp = drp->dr_ifp; 470 471 /* Get rid of expired discovered routers. 472 */ 473 if (drp->dr_ts + drp->dr_life <= now.tv_sec) { 474 del_rdisc(drp); 475 continue; 476 } 477 478 LIM_SEC(rdisc_timer, drp->dr_ts+drp->dr_life+1); 479 480 /* Update preference with possibly changed interface 481 * metric. 482 */ 483 drp->dr_pref = PREF(drp->dr_recv_pref, ifp); 484 485 /* Prefer the current route to prevent thrashing. 486 * Prefer shorter lifetimes to speed the detection of 487 * bad routers. 488 * Avoid sick interfaces. 489 */ 490 if (new_drp == 0 491 || (!((new_st ^ drp->dr_ifp->int_state) & IS_SICK) 492 && (new_pref < drp->dr_pref 493 || (new_pref == drp->dr_pref 494 && (drp == cur_drp 495 || (new_drp != cur_drp 496 && new_drp->dr_life > drp->dr_life))))) 497 || ((new_st & IS_SICK) 498 && !(drp->dr_ifp->int_state & IS_SICK))) { 499 new_drp = drp; 500 new_st = drp->dr_ifp->int_state; 501 new_pref = drp->dr_pref; 502 } 503 } 504 505 /* switch to a better default route 506 */ 507 if (new_drp != cur_drp) { 508 rt = rtget(RIP_DEFAULT, 0); 509 510 /* Stop using discovered routes if they are all bad 511 */ 512 if (new_drp == 0) { 513 trace_act("turn off Router Discovery client"); 514 rdisc_ok = 0; 515 516 if (rt != 0 517 && (rt->rt_state & RS_RDISC)) { 518 new = rt->rt_spares[0]; 519 new.rts_metric = HOPCNT_INFINITY; 520 new.rts_time = now.tv_sec - GARBAGE_TIME; 521 rtchange(rt, rt->rt_state & ~RS_RDISC, 522 &new, 0); 523 rtswitch(rt, 0); 524 } 525 526 } else { 527 if (cur_drp == 0) { 528 trace_act("turn on Router Discovery client" 529 " using %s via %s", 530 naddr_ntoa(new_drp->dr_gate), 531 new_drp->dr_ifp->int_name); 532 rdisc_ok = 1; 533 534 } else { 535 trace_act("switch Router Discovery from" 536 " %s via %s to %s via %s", 537 naddr_ntoa(cur_drp->dr_gate), 538 cur_drp->dr_ifp->int_name, 539 naddr_ntoa(new_drp->dr_gate), 540 new_drp->dr_ifp->int_name); 541 } 542 543 memset(&new, 0, sizeof(new)); 544 new.rts_ifp = new_drp->dr_ifp; 545 new.rts_gate = new_drp->dr_gate; 546 new.rts_router = new_drp->dr_gate; 547 new.rts_metric = HOPCNT_INFINITY-1; 548 new.rts_time = now.tv_sec; 549 if (rt != 0) { 550 rtchange(rt, rt->rt_state | RS_RDISC, &new, 0); 551 } else { 552 rtadd(RIP_DEFAULT, 0, RS_RDISC, &new); 553 } 554 } 555 556 cur_drp = new_drp; 557 } 558 559 /* turn RIP on or off */ 560 if (!rdisc_ok || rip_interfaces > 1) { 561 rip_on(0); 562 } else { 563 rip_off(); 564 } 565 } 566 567 568 /* handle a single address in an advertisement 569 */ 570 static void 571 parse_ad(naddr from, 572 naddr gate, 573 n_long pref, /* signed and in network order */ 574 u_short life, 575 struct interface *ifp) 576 { 577 static struct msg_limit bad_gate; 578 struct dr *drp, *new_drp; 579 580 581 if (gate == RIP_DEFAULT 582 || !check_dst(gate)) { 583 msglim(&bad_gate, from,"router %s advertising bad gateway %s", 584 naddr_ntoa(from), 585 naddr_ntoa(gate)); 586 return; 587 } 588 589 /* ignore pointers to ourself and routes via unreachable networks 590 */ 591 if (ifwithaddr(gate, 1, 0) != 0) { 592 trace_pkt(" discard Router Discovery Ad pointing at us"); 593 return; 594 } 595 if (!on_net(gate, ifp->int_net, ifp->int_mask)) { 596 trace_pkt(" discard Router Discovery Ad" 597 " toward unreachable net"); 598 return; 599 } 600 601 /* Convert preference to an unsigned value 602 * and later bias it by the metric of the interface. 603 */ 604 pref = UNSIGN_PREF(ntohl(pref)); 605 606 if (pref == 0 || life < MinMaxAdvertiseInterval) { 607 pref = 0; 608 life = 0; 609 } 610 611 for (new_drp = 0, drp = drs; drp < &drs[MAX_ADS]; drp++) { 612 /* accept new info for a familiar entry 613 */ 614 if (drp->dr_gate == gate) { 615 new_drp = drp; 616 break; 617 } 618 619 if (life == 0) 620 continue; /* do not worry about dead ads */ 621 622 if (drp->dr_ts == 0) { 623 new_drp = drp; /* use unused entry */ 624 625 } else if (new_drp == 0) { 626 /* look for an entry worse than the new one to 627 * reuse. 628 */ 629 if ((!(ifp->int_state & IS_SICK) 630 && (drp->dr_ifp->int_state & IS_SICK)) 631 || (pref > drp->dr_pref 632 && !((ifp->int_state ^ drp->dr_ifp->int_state) 633 & IS_SICK))) 634 new_drp = drp; 635 636 } else if (new_drp->dr_ts != 0) { 637 /* look for the least valuable entry to reuse 638 */ 639 if ((!(new_drp->dr_ifp->int_state & IS_SICK) 640 && (drp->dr_ifp->int_state & IS_SICK)) 641 || (new_drp->dr_pref > drp->dr_pref 642 && !((new_drp->dr_ifp->int_state 643 ^ drp->dr_ifp->int_state) 644 & IS_SICK))) 645 new_drp = drp; 646 } 647 } 648 649 /* forget it if all of the current entries are better */ 650 if (new_drp == 0) 651 return; 652 653 new_drp->dr_ifp = ifp; 654 new_drp->dr_gate = gate; 655 new_drp->dr_ts = now.tv_sec; 656 new_drp->dr_life = ntohs(life); 657 new_drp->dr_recv_pref = pref; 658 /* bias functional preference by metric of the interface */ 659 new_drp->dr_pref = PREF(pref,ifp); 660 661 /* after hearing a good advertisement, stop asking 662 */ 663 if (!(ifp->int_state & IS_SICK)) 664 ifp->int_rdisc_cnt = MAX_SOLICITATIONS; 665 } 666 667 668 /* Compute the IP checksum 669 * This assumes the packet is less than 32K long. 670 */ 671 static u_short 672 in_cksum(u_short *p, 673 u_int len) 674 { 675 u_int sum = 0; 676 int nwords = len >> 1; 677 678 while (nwords-- != 0) 679 sum += *p++; 680 681 if (len & 1) 682 sum += *(u_char *)p; 683 684 /* end-around-carry */ 685 sum = (sum >> 16) + (sum & 0xffff); 686 sum += (sum >> 16); 687 return (~sum); 688 } 689 690 691 /* Send a router discovery advertisement or solicitation ICMP packet. 692 */ 693 static void 694 send_rdisc(union ad_u *p, 695 int p_size, 696 struct interface *ifp, 697 naddr dst, /* 0 or unicast destination */ 698 int type) /* 0=unicast, 1=bcast, 2=mcast */ 699 { 700 struct sockaddr_in sin; 701 int flags; 702 const char *msg; 703 naddr tgt_mcast; 704 705 706 memset(&sin, 0, sizeof(sin)); 707 sin.sin_addr.s_addr = dst; 708 sin.sin_family = AF_INET; 709 #ifdef _HAVE_SIN_LEN 710 sin.sin_len = sizeof(sin); 711 #endif 712 flags = MSG_DONTROUTE; 713 714 switch (type) { 715 case 0: /* unicast */ 716 default: 717 msg = "Send"; 718 break; 719 720 case 1: /* broadcast */ 721 if (ifp->int_if_flags & IFF_POINTOPOINT) { 722 msg = "Send pt-to-pt"; 723 sin.sin_addr.s_addr = ifp->int_dstaddr; 724 } else { 725 msg = "Send broadcast"; 726 sin.sin_addr.s_addr = ifp->int_brdaddr; 727 } 728 break; 729 730 case 2: /* multicast */ 731 msg = "Send multicast"; 732 if (ifp->int_state & IS_DUP) { 733 trace_act("abort multicast output via %s" 734 " with duplicate address", 735 ifp->int_name); 736 return; 737 } 738 if (rdisc_sock_mcast != ifp) { 739 /* select the right interface. */ 740 #ifdef MCAST_IFINDEX 741 /* specify ifindex */ 742 tgt_mcast = htonl(ifp->int_index); 743 #else 744 #ifdef MCAST_PPP_BUG 745 /* Do not specify the primary interface explicitly 746 * if we have the multicast point-to-point kernel 747 * bug, since the kernel will do the wrong thing 748 * if the local address of a point-to-point link 749 * is the same as the address of an ordinary 750 * interface. 751 */ 752 if (ifp->int_addr == myaddr) { 753 tgt_mcast = 0; 754 } else 755 #endif 756 tgt_mcast = ifp->int_addr; 757 #endif 758 if (0 > setsockopt(rdisc_sock, 759 IPPROTO_IP, IP_MULTICAST_IF, 760 &tgt_mcast, sizeof(tgt_mcast))) { 761 LOGERR("setsockopt(rdisc_sock," 762 "IP_MULTICAST_IF)"); 763 rdisc_sock_mcast = 0; 764 return; 765 } 766 rdisc_sock_mcast = ifp; 767 } 768 flags = 0; 769 break; 770 } 771 772 if (rdisc_sock < 0) 773 get_rdisc_sock(); 774 775 trace_rdisc(msg, ifp->int_addr, sin.sin_addr.s_addr, ifp, 776 p, p_size); 777 778 if (0 > sendto(rdisc_sock, p, p_size, flags, 779 (struct sockaddr *)&sin, sizeof(sin))) { 780 if (ifp == 0 || !(ifp->int_state & IS_BROKE)) 781 msglog("sendto(%s%s%s): %s", 782 ifp != 0 ? ifp->int_name : "", 783 ifp != 0 ? ", " : "", 784 inet_ntoa(sin.sin_addr), 785 strerror(errno)); 786 if (ifp != 0) 787 if_sick(ifp); 788 } 789 } 790 791 792 /* Send an advertisement 793 */ 794 static void 795 send_adv(struct interface *ifp, 796 naddr dst, /* 0 or unicast destination */ 797 int type) /* 0=unicast, 1=bcast, 2=mcast */ 798 { 799 union ad_u u; 800 n_long pref; 801 802 803 memset(&u, 0, sizeof(u.ad)); 804 805 u.ad.icmp_type = ICMP_ROUTERADVERT; 806 u.ad.icmp_ad_num = 1; 807 u.ad.icmp_ad_asize = sizeof(u.ad.icmp_ad_info[0])/4; 808 809 u.ad.icmp_ad_life = stopint ? 0 : htons(ifp->int_rdisc_int*3); 810 811 /* Convert the configured preference to an unsigned value, 812 * bias it by the interface metric, and then send it as a 813 * signed, network byte order value. 814 */ 815 pref = UNSIGN_PREF(ifp->int_rdisc_pref); 816 u.ad.icmp_ad_info[0].icmp_ad_pref = htonl(SIGN_PREF(PREF(pref, ifp))); 817 818 u.ad.icmp_ad_info[0].icmp_ad_addr = ifp->int_addr; 819 820 u.ad.icmp_cksum = in_cksum((u_short*)&u.ad, sizeof(u.ad)); 821 822 send_rdisc(&u, sizeof(u.ad), ifp, dst, type); 823 } 824 825 826 /* Advertise for Router Discovery 827 */ 828 void 829 rdisc_adv(void) 830 { 831 struct interface *ifp; 832 833 if (!supplier) 834 return; 835 836 rdisc_timer.tv_sec = now.tv_sec + NEVER; 837 838 for (ifp = ifnet; ifp; ifp = ifp->int_next) { 839 if (0 != (ifp->int_state & (IS_NO_ADV_OUT | IS_BROKE))) 840 continue; 841 842 if (!timercmp(&ifp->int_rdisc_timer, &now, >) 843 || stopint) { 844 send_adv(ifp, htonl(INADDR_ALLHOSTS_GROUP), 845 (ifp->int_state&IS_BCAST_RDISC) ? 1 : 2); 846 ifp->int_rdisc_cnt++; 847 848 intvl_random(&ifp->int_rdisc_timer, 849 (ifp->int_rdisc_int*3)/4, 850 ifp->int_rdisc_int); 851 if (ifp->int_rdisc_cnt < MAX_INITIAL_ADVERTS 852 && (ifp->int_rdisc_timer.tv_sec 853 > MAX_INITIAL_ADVERT_INTERVAL)) { 854 ifp->int_rdisc_timer.tv_sec 855 = MAX_INITIAL_ADVERT_INTERVAL; 856 } 857 timevaladd(&ifp->int_rdisc_timer, &now); 858 } 859 860 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 861 rdisc_timer = ifp->int_rdisc_timer; 862 } 863 } 864 865 866 /* Solicit for Router Discovery 867 */ 868 void 869 rdisc_sol(void) 870 { 871 struct interface *ifp; 872 union ad_u u; 873 874 875 if (supplier) 876 return; 877 878 rdisc_timer.tv_sec = now.tv_sec + NEVER; 879 880 for (ifp = ifnet; ifp; ifp = ifp->int_next) { 881 if (0 != (ifp->int_state & (IS_NO_SOL_OUT | IS_BROKE)) 882 || ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) 883 continue; 884 885 if (!timercmp(&ifp->int_rdisc_timer, &now, >)) { 886 memset(&u, 0, sizeof(u.so)); 887 u.so.icmp_type = ICMP_ROUTERSOLICIT; 888 u.so.icmp_cksum = in_cksum((u_short*)&u.so, 889 sizeof(u.so)); 890 send_rdisc(&u, sizeof(u.so), ifp, 891 htonl(INADDR_ALLROUTERS_GROUP), 892 ((ifp->int_state&IS_BCAST_RDISC) ? 1 : 2)); 893 894 if (++ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) 895 continue; 896 897 ifp->int_rdisc_timer.tv_sec = SOLICITATION_INTERVAL; 898 ifp->int_rdisc_timer.tv_usec = 0; 899 timevaladd(&ifp->int_rdisc_timer, &now); 900 } 901 902 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 903 rdisc_timer = ifp->int_rdisc_timer; 904 } 905 } 906 907 908 /* check the IP header of a possible Router Discovery ICMP packet */ 909 static struct interface * /* 0 if bad */ 910 ck_icmp(const char *act, 911 naddr from, 912 struct interface *ifp, 913 naddr to, 914 union ad_u *p, 915 u_int len) 916 { 917 const char *type; 918 919 920 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) { 921 type = "advertisement"; 922 } else if (p->icmp.icmp_type == ICMP_ROUTERSOLICIT) { 923 type = "solicitation"; 924 } else { 925 return 0; 926 } 927 928 if (p->icmp.icmp_code != 0) { 929 trace_pkt("unrecognized ICMP Router %s code=%d from %s to %s", 930 type, p->icmp.icmp_code, 931 naddr_ntoa(from), naddr_ntoa(to)); 932 return 0; 933 } 934 935 trace_rdisc(act, from, to, ifp, p, len); 936 937 if (ifp == 0) 938 trace_pkt("unknown interface for router-discovery %s" 939 " from %s to %s", 940 type, naddr_ntoa(from), naddr_ntoa(to)); 941 942 return ifp; 943 } 944 945 946 /* read packets from the router discovery socket 947 */ 948 void 949 read_d(void) 950 { 951 static struct msg_limit bad_asize, bad_len; 952 #ifdef USE_PASSIFNAME 953 static struct msg_limit bad_name; 954 #endif 955 struct sockaddr_in from; 956 int n, fromlen, cc, hlen; 957 struct { 958 #ifdef USE_PASSIFNAME 959 char ifname[IFNAMSIZ]; 960 #endif 961 union { 962 struct ip ip; 963 u_short s[512/2]; 964 u_char b[512]; 965 } pkt; 966 } buf; 967 union ad_u *p; 968 n_long *wp; 969 struct interface *ifp; 970 971 972 for (;;) { 973 fromlen = sizeof(from); 974 cc = recvfrom(rdisc_sock, &buf, sizeof(buf), 0, 975 (struct sockaddr*)&from, 976 &fromlen); 977 if (cc <= 0) { 978 if (cc < 0 && errno != EWOULDBLOCK) 979 LOGERR("recvfrom(rdisc_sock)"); 980 break; 981 } 982 if (fromlen != sizeof(struct sockaddr_in)) 983 logbad(1,"impossible recvfrom(rdisc_sock) fromlen=%d", 984 fromlen); 985 #ifdef USE_PASSIFNAME 986 if ((cc -= sizeof(buf.ifname)) < 0) 987 logbad(0,"missing USE_PASSIFNAME; only %d bytes", 988 cc+sizeof(buf.ifname)); 989 #endif 990 991 hlen = buf.pkt.ip.ip_hl << 2; 992 if (cc < hlen + ICMP_MINLEN) 993 continue; 994 p = (union ad_u *)&buf.pkt.b[hlen]; 995 cc -= hlen; 996 997 #ifdef USE_PASSIFNAME 998 ifp = ifwithname(buf.ifname, 0); 999 if (ifp == 0) 1000 msglim(&bad_name, from.sin_addr.s_addr, 1001 "impossible rdisc if_ name %.*s", 1002 IFNAMSIZ, buf.ifname); 1003 #else 1004 /* If we could tell the interface on which a packet from 1005 * address 0 arrived, we could deal with such solicitations. 1006 */ 1007 ifp = ((from.sin_addr.s_addr == 0) 1008 ? 0 : iflookup(from.sin_addr.s_addr)); 1009 #endif 1010 ifp = ck_icmp("Recv", from.sin_addr.s_addr, ifp, 1011 buf.pkt.ip.ip_dst.s_addr, p, cc); 1012 if (ifp == 0) 1013 continue; 1014 if (ifwithaddr(from.sin_addr.s_addr, 0, 0)) { 1015 trace_pkt(" " 1016 "discard our own Router Discovery message"); 1017 continue; 1018 } 1019 1020 switch (p->icmp.icmp_type) { 1021 case ICMP_ROUTERADVERT: 1022 if (p->ad.icmp_ad_asize*4 1023 < (int)sizeof(p->ad.icmp_ad_info[0])) { 1024 msglim(&bad_asize, from.sin_addr.s_addr, 1025 "intolerable rdisc address size=%d", 1026 p->ad.icmp_ad_asize); 1027 continue; 1028 } 1029 if (p->ad.icmp_ad_num == 0) { 1030 trace_pkt(" empty?"); 1031 continue; 1032 } 1033 if (cc != (int)(sizeof(p->ad) 1034 - sizeof(p->ad.icmp_ad_info) 1035 + (p->ad.icmp_ad_num 1036 * sizeof(p->ad.icmp_ad_info[0])))) { 1037 msglim(&bad_len, from.sin_addr.s_addr, 1038 "rdisc length %d does not match ad_num" 1039 " %d", cc, p->ad.icmp_ad_num); 1040 continue; 1041 } 1042 if (supplier) 1043 continue; 1044 if (ifp->int_state & IS_NO_ADV_IN) 1045 continue; 1046 1047 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr; 1048 for (n = 0; n < p->ad.icmp_ad_num; n++) { 1049 parse_ad(from.sin_addr.s_addr, 1050 wp[0], wp[1], 1051 ntohs(p->ad.icmp_ad_life), 1052 ifp); 1053 wp += p->ad.icmp_ad_asize; 1054 } 1055 break; 1056 1057 1058 case ICMP_ROUTERSOLICIT: 1059 if (!supplier) 1060 continue; 1061 if (ifp->int_state & IS_NO_ADV_OUT) 1062 continue; 1063 if (stopint) 1064 continue; 1065 1066 /* XXX 1067 * We should handle messages from address 0. 1068 */ 1069 1070 /* Respond with a point-to-point advertisement */ 1071 send_adv(ifp, from.sin_addr.s_addr, 0); 1072 break; 1073 } 1074 } 1075 1076 rdisc_sort(); 1077 } 1078
Indexes created Tue Sep 23 23:09:58 GMT 2025