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 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $FreeBSD$ 30 */ 31 32 #include "defs.h" 33 #include <netinet/in_systm.h> 34 #include <netinet/ip.h> 35 #include <netinet/ip_icmp.h> 36 37 #ifdef __NetBSD__ 38 __RCSID("$NetBSD$"); 39 #elif defined(__FreeBSD__) 40 __RCSID("$FreeBSD$"); 41 #else 42 __RCSID("$Revision: 2.27 $"); 43 #ident "$Revision: 2.27 $" 44 #endif 45 46 /* router advertisement ICMP packet */ 47 struct icmp_ad { 48 u_int8_t icmp_type; /* type of message */ 49 u_int8_t icmp_code; /* type sub code */ 50 u_int16_t icmp_cksum; /* ones complement cksum of struct */ 51 u_int8_t icmp_ad_num; /* # of following router addresses */ 52 u_int8_t icmp_ad_asize; /* 2--words in each advertisement */ 53 u_int16_t icmp_ad_life; /* seconds of validity */ 54 struct icmp_ad_info { 55 n_long icmp_ad_addr; 56 n_long icmp_ad_pref; 57 } icmp_ad_info[1]; 58 }; 59 60 /* router solicitation ICMP packet */ 61 struct icmp_so { 62 u_int8_t icmp_type; /* type of message */ 63 u_int8_t icmp_code; /* type sub code */ 64 u_int16_t icmp_cksum; /* ones complement cksum of struct */ 65 n_long icmp_so_rsvd; 66 }; 67 68 union ad_u { 69 struct icmp icmp; 70 struct icmp_ad ad; 71 struct icmp_so so; 72 }; 73 74 75 int rdisc_sock = -1; /* router-discovery raw socket */ 76 static const struct interface *rdisc_sock_mcast; /* current multicast interface */ 77 78 struct timeval rdisc_timer; 79 int rdisc_ok; /* using solicited route */ 80 81 82 #define MAX_ADS 16 /* at least one per interface */ 83 struct dr { /* accumulated advertisements */ 84 struct interface *dr_ifp; 85 naddr dr_gate; /* gateway */ 86 time_t dr_ts; /* when received */ 87 time_t dr_life; /* lifetime in host byte order */ 88 n_long dr_recv_pref; /* received but biased preference */ 89 n_long dr_pref; /* preference adjusted by metric */ 90 }; 91 static const struct dr *cur_drp; 92 static struct dr 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+(ifp)->int_adj_outmetric)\ 101 ? ((p) != 0 ? 1 : 0) \ 102 : (p) - ((ifp)->int_metric+(ifp)->int_adj_outmetric)) 103 104 static void rdisc_sort(void); 105 106 107 /* dump an ICMP Router Discovery Advertisement Message 108 */ 109 static void 110 trace_rdisc(const char *act, 111 naddr from, 112 naddr to, 113 struct interface *ifp, 114 union ad_u *p, 115 u_int len) 116 { 117 int i; 118 n_long *wp, *lim; 119 120 121 if (!TRACEPACKETS || ftrace == NULL) 122 return; 123 124 lastlog(); 125 126 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) { 127 (void)fprintf(ftrace, "%s Router Ad" 128 " from %s to %s via %s life=%d\n", 129 act, naddr_ntoa(from), naddr_ntoa(to), 130 ifp ? ifp->int_name : "?", 131 ntohs(p->ad.icmp_ad_life)); 132 if (!TRACECONTENTS) 133 return; 134 135 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr; 136 lim = &wp[(len - sizeof(p->ad)) / sizeof(*wp)]; 137 for (i = 0; i < p->ad.icmp_ad_num && wp <= lim; i++) { 138 (void)fprintf(ftrace, "\t%s preference=%d", 139 naddr_ntoa(wp[0]), (int)ntohl(wp[1])); 140 wp += p->ad.icmp_ad_asize; 141 } 142 (void)fputc('\n',ftrace); 143 144 } else { 145 trace_act("%s Router Solic. from %s to %s via %s value=%#x", 146 act, naddr_ntoa(from), naddr_ntoa(to), 147 ifp ? ifp->int_name : "?", 148 (int)ntohl(p->so.icmp_so_rsvd)); 149 } 150 } 151 152 /* prepare Router Discovery socket. 153 */ 154 static void 155 get_rdisc_sock(void) 156 { 157 if (rdisc_sock < 0) { 158 rdisc_sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); 159 if (rdisc_sock < 0) 160 BADERR(1,"rdisc_sock = socket()"); 161 fix_sock(rdisc_sock,"rdisc_sock"); 162 fix_select(); 163 } 164 } 165 166 167 /* Pick multicast group for router-discovery socket 168 */ 169 void 170 set_rdisc_mg(struct interface *ifp, 171 int on) /* 0=turn it off */ 172 { 173 struct group_req gr; 174 struct sockaddr_in *sin; 175 176 assert(ifp != NULL); 177 178 if (rdisc_sock < 0) { 179 /* Create the raw socket so that we can hear at least 180 * broadcast router discovery packets. 181 */ 182 if ((ifp->int_state & IS_NO_RDISC) == IS_NO_RDISC 183 || !on) 184 return; 185 get_rdisc_sock(); 186 } 187 188 if (!(ifp->int_if_flags & IFF_MULTICAST)) { 189 ifp->int_state &= ~(IS_ALL_HOSTS | IS_ALL_ROUTERS); 190 return; 191 } 192 193 memset(&gr, 0, sizeof(gr)); 194 gr.gr_interface = ifp->int_index; 195 sin = (struct sockaddr_in *)&gr.gr_group; 196 sin->sin_family = AF_INET; 197 #ifdef _HAVE_SIN_LEN 198 sin->sin_len = sizeof(struct sockaddr_in); 199 #endif 200 201 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 sin->sin_addr.s_addr = htonl(INADDR_ALLHOSTS_GROUP); 208 if (setsockopt(rdisc_sock, IPPROTO_IP, 209 MCAST_LEAVE_GROUP, 210 &gr, sizeof(gr)) < 0) 211 LOGERR("MCAST_LEAVE_GROUP 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 sin->sin_addr.s_addr = htonl(INADDR_ALLHOSTS_GROUP); 219 if (setsockopt(rdisc_sock, IPPROTO_IP, MCAST_JOIN_GROUP, 220 &gr, sizeof(gr)) < 0) { 221 LOGERR("MCAST_JOIN_GROUP 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 sin->sin_addr.s_addr = htonl(INADDR_ALLROUTERS_GROUP); 234 if (setsockopt(rdisc_sock, IPPROTO_IP, 235 MCAST_LEAVE_GROUP, 236 &gr, sizeof(gr)) < 0) 237 LOGERR("MCAST_LEAVE_GROUP 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 sin->sin_addr.s_addr = htonl(INADDR_ALLROUTERS_GROUP); 245 if (setsockopt(rdisc_sock, IPPROTO_IP, MCAST_JOIN_GROUP, 246 &gr, sizeof(gr)) < 0) { 247 LOGERR("MCAST_JOIN_GROUP 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 LIST_FOREACH(ifp, &ifnet, int_list) { 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 != NULL) 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 = NULL; 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 == NULL 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 == NULL) { 513 trace_act("turn off Router Discovery client"); 514 rdisc_ok = 0; 515 516 if (rt != NULL 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 == NULL) { 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 != NULL) { 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, /* in host byte order */ 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) != NULL) { 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 = NULL, 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 == NULL) { 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 == NULL) 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 = 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 rsin; 701 int flags; 702 const char *msg; 703 704 705 memset(&rsin, 0, sizeof(rsin)); 706 rsin.sin_addr.s_addr = dst; 707 rsin.sin_family = AF_INET; 708 #ifdef _HAVE_SIN_LEN 709 rsin.sin_len = sizeof(rsin); 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 rsin.sin_addr.s_addr = ifp->int_dstaddr; 723 } else { 724 msg = "Send broadcast"; 725 rsin.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 struct ip_mreqn mreqn; 740 741 memset(&mreqn, 0, sizeof(struct ip_mreqn)); 742 mreqn.imr_ifindex = ifp->int_index; 743 if (0 > setsockopt(rdisc_sock, 744 IPPROTO_IP, IP_MULTICAST_IF, 745 &mreqn, 746 sizeof(mreqn))) { 747 LOGERR("setsockopt(rdisc_sock," 748 "IP_MULTICAST_IF)"); 749 rdisc_sock_mcast = NULL; 750 return; 751 } 752 rdisc_sock_mcast = ifp; 753 } 754 flags = 0; 755 break; 756 } 757 758 if (rdisc_sock < 0) 759 get_rdisc_sock(); 760 761 trace_rdisc(msg, (ifp ? ifp->int_addr : 0), rsin.sin_addr.s_addr, ifp, 762 p, p_size); 763 764 if (0 > sendto(rdisc_sock, p, p_size, flags, 765 (struct sockaddr *)&rsin, sizeof(rsin))) { 766 if (ifp == NULL || !(ifp->int_state & IS_BROKE)) 767 msglog("sendto(%s%s%s): %s", 768 ifp != NULL ? ifp->int_name : "", 769 ifp != NULL ? ", " : "", 770 inet_ntoa(rsin.sin_addr), 771 strerror(errno)); 772 if (ifp != NULL) 773 if_sick(ifp); 774 } 775 } 776 777 778 /* Send an advertisement 779 */ 780 static void 781 send_adv(struct interface *ifp, 782 naddr dst, /* 0 or unicast destination */ 783 int type) /* 0=unicast, 1=bcast, 2=mcast */ 784 { 785 union ad_u u; 786 n_long pref; 787 788 789 memset(&u, 0, sizeof(u.ad)); 790 791 u.ad.icmp_type = ICMP_ROUTERADVERT; 792 u.ad.icmp_ad_num = 1; 793 u.ad.icmp_ad_asize = sizeof(u.ad.icmp_ad_info[0])/4; 794 795 u.ad.icmp_ad_life = stopint ? 0 : htons(ifp->int_rdisc_int*3); 796 797 /* Convert the configured preference to an unsigned value, 798 * bias it by the interface metric, and then send it as a 799 * signed, network byte order value. 800 */ 801 pref = UNSIGN_PREF(ifp->int_rdisc_pref); 802 u.ad.icmp_ad_info[0].icmp_ad_pref = htonl(SIGN_PREF(PREF(pref, ifp))); 803 804 u.ad.icmp_ad_info[0].icmp_ad_addr = ifp->int_addr; 805 806 u.ad.icmp_cksum = in_cksum((u_short*)&u.ad, sizeof(u.ad)); 807 808 send_rdisc(&u, sizeof(u.ad), ifp, dst, type); 809 } 810 811 812 /* Advertise for Router Discovery 813 */ 814 void 815 rdisc_adv(void) 816 { 817 struct interface *ifp; 818 819 if (!supplier) 820 return; 821 822 rdisc_timer.tv_sec = now.tv_sec + NEVER; 823 824 LIST_FOREACH(ifp, &ifnet, int_list) { 825 if (0 != (ifp->int_state & (IS_NO_ADV_OUT | IS_BROKE))) 826 continue; 827 828 if (!timercmp(&ifp->int_rdisc_timer, &now, >) 829 || stopint) { 830 send_adv(ifp, htonl(INADDR_ALLHOSTS_GROUP), 831 (ifp->int_state&IS_BCAST_RDISC) ? 1 : 2); 832 ifp->int_rdisc_cnt++; 833 834 intvl_random(&ifp->int_rdisc_timer, 835 (ifp->int_rdisc_int*3)/4, 836 ifp->int_rdisc_int); 837 if (ifp->int_rdisc_cnt < MAX_INITIAL_ADVERTS 838 && (ifp->int_rdisc_timer.tv_sec 839 > MAX_INITIAL_ADVERT_INTERVAL)) { 840 ifp->int_rdisc_timer.tv_sec 841 = MAX_INITIAL_ADVERT_INTERVAL; 842 } 843 timevaladd(&ifp->int_rdisc_timer, &now); 844 } 845 846 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 847 rdisc_timer = ifp->int_rdisc_timer; 848 } 849 } 850 851 852 /* Solicit for Router Discovery 853 */ 854 void 855 rdisc_sol(void) 856 { 857 struct interface *ifp; 858 union ad_u u; 859 860 861 if (supplier) 862 return; 863 864 rdisc_timer.tv_sec = now.tv_sec + NEVER; 865 866 LIST_FOREACH(ifp, &ifnet, int_list) { 867 if (0 != (ifp->int_state & (IS_NO_SOL_OUT | IS_BROKE)) 868 || ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) 869 continue; 870 871 if (!timercmp(&ifp->int_rdisc_timer, &now, >)) { 872 memset(&u, 0, sizeof(u.so)); 873 u.so.icmp_type = ICMP_ROUTERSOLICIT; 874 u.so.icmp_cksum = in_cksum((u_short*)&u.so, 875 sizeof(u.so)); 876 send_rdisc(&u, sizeof(u.so), ifp, 877 htonl(INADDR_ALLROUTERS_GROUP), 878 ((ifp->int_state&IS_BCAST_RDISC) ? 1 : 2)); 879 880 if (++ifp->int_rdisc_cnt >= MAX_SOLICITATIONS) 881 continue; 882 883 ifp->int_rdisc_timer.tv_sec = SOLICITATION_INTERVAL; 884 ifp->int_rdisc_timer.tv_usec = 0; 885 timevaladd(&ifp->int_rdisc_timer, &now); 886 } 887 888 if (timercmp(&rdisc_timer, &ifp->int_rdisc_timer, >)) 889 rdisc_timer = ifp->int_rdisc_timer; 890 } 891 } 892 893 894 /* check the IP header of a possible Router Discovery ICMP packet */ 895 static struct interface * /* 0 if bad */ 896 ck_icmp(const char *act, 897 naddr from, 898 struct interface *ifp, 899 naddr to, 900 union ad_u *p, 901 u_int len) 902 { 903 const char *type; 904 905 906 if (p->icmp.icmp_type == ICMP_ROUTERADVERT) { 907 type = "advertisement"; 908 } else if (p->icmp.icmp_type == ICMP_ROUTERSOLICIT) { 909 type = "solicitation"; 910 } else { 911 return 0; 912 } 913 914 if (p->icmp.icmp_code != 0) { 915 trace_pkt("unrecognized ICMP Router %s code=%d from %s to %s", 916 type, p->icmp.icmp_code, 917 naddr_ntoa(from), naddr_ntoa(to)); 918 return 0; 919 } 920 921 trace_rdisc(act, from, to, ifp, p, len); 922 923 if (ifp == NULL) 924 trace_pkt("unknown interface for router-discovery %s" 925 " from %s to %s", 926 type, naddr_ntoa(from), naddr_ntoa(to)); 927 928 return ifp; 929 } 930 931 932 /* read packets from the router discovery socket 933 */ 934 void 935 read_d(void) 936 { 937 static struct msg_limit bad_asize, bad_len; 938 #ifdef USE_PASSIFNAME 939 static struct msg_limit bad_name; 940 #endif 941 struct sockaddr_in from; 942 int n, fromlen, cc, hlen; 943 struct { 944 #ifdef USE_PASSIFNAME 945 char ifname[IFNAMSIZ]; 946 #endif 947 union { 948 struct ip ip; 949 u_char b[512]; 950 } pkt; 951 } buf; 952 union ad_u *p; 953 n_long *wp; 954 struct interface *ifp; 955 956 957 for (;;) { 958 fromlen = sizeof(from); 959 cc = recvfrom(rdisc_sock, &buf, sizeof(buf), 0, 960 (struct sockaddr*)&from, 961 &fromlen); 962 if (cc <= 0) { 963 if (cc < 0 && errno != EWOULDBLOCK) 964 LOGERR("recvfrom(rdisc_sock)"); 965 break; 966 } 967 if (fromlen != sizeof(struct sockaddr_in)) 968 logbad(1,"impossible recvfrom(rdisc_sock) fromlen=%d", 969 fromlen); 970 #ifdef USE_PASSIFNAME 971 if ((cc -= sizeof(buf.ifname)) < 0) 972 logbad(0,"missing USE_PASSIFNAME; only %d bytes", 973 cc+sizeof(buf.ifname)); 974 #endif 975 976 hlen = buf.pkt.ip.ip_hl << 2; 977 if (cc < hlen + ICMP_MINLEN) 978 continue; 979 p = (union ad_u *)&buf.pkt.b[hlen]; 980 cc -= hlen; 981 982 #ifdef USE_PASSIFNAME 983 ifp = ifwithname(buf.ifname, 0); 984 if (ifp == NULL) 985 msglim(&bad_name, from.sin_addr.s_addr, 986 "impossible rdisc if_ name %.*s", 987 IFNAMSIZ, buf.ifname); 988 #else 989 /* If we could tell the interface on which a packet from 990 * address 0 arrived, we could deal with such solicitations. 991 */ 992 ifp = ((from.sin_addr.s_addr == 0) 993 ? 0 : iflookup(from.sin_addr.s_addr)); 994 #endif 995 ifp = ck_icmp("Recv", from.sin_addr.s_addr, ifp, 996 buf.pkt.ip.ip_dst.s_addr, p, cc); 997 if (ifp == NULL) 998 continue; 999 if (ifwithaddr(from.sin_addr.s_addr, 0, 0)) { 1000 trace_pkt(" " 1001 "discard our own Router Discovery message"); 1002 continue; 1003 } 1004 1005 switch (p->icmp.icmp_type) { 1006 case ICMP_ROUTERADVERT: 1007 if (p->ad.icmp_ad_asize*4 1008 < (int)sizeof(p->ad.icmp_ad_info[0])) { 1009 msglim(&bad_asize, from.sin_addr.s_addr, 1010 "intolerable rdisc address size=%d", 1011 p->ad.icmp_ad_asize); 1012 continue; 1013 } 1014 if (p->ad.icmp_ad_num == 0) { 1015 trace_pkt(" empty?"); 1016 continue; 1017 } 1018 if (cc != (int)(sizeof(p->ad) 1019 - sizeof(p->ad.icmp_ad_info) 1020 + (p->ad.icmp_ad_num 1021 * sizeof(p->ad.icmp_ad_info[0])))) { 1022 msglim(&bad_len, from.sin_addr.s_addr, 1023 "rdisc length %d does not match ad_num" 1024 " %d", cc, p->ad.icmp_ad_num); 1025 continue; 1026 } 1027 if (supplier) 1028 continue; 1029 if (ifp->int_state & IS_NO_ADV_IN) 1030 continue; 1031 1032 wp = &p->ad.icmp_ad_info[0].icmp_ad_addr; 1033 for (n = 0; n < p->ad.icmp_ad_num; n++) { 1034 parse_ad(from.sin_addr.s_addr, 1035 wp[0], wp[1], 1036 ntohs(p->ad.icmp_ad_life), 1037 ifp); 1038 wp += p->ad.icmp_ad_asize; 1039 } 1040 break; 1041 1042 1043 case ICMP_ROUTERSOLICIT: 1044 if (!supplier) 1045 continue; 1046 if (ifp->int_state & IS_NO_ADV_OUT) 1047 continue; 1048 if (stopint) 1049 continue; 1050 1051 /* XXX 1052 * We should handle messages from address 0. 1053 */ 1054 1055 /* Respond with a point-to-point advertisement */ 1056 send_adv(ifp, from.sin_addr.s_addr, 0); 1057 break; 1058 } 1059 } 1060 1061 rdisc_sort(); 1062 } 1063