1 /* $OpenBSD: dispatch.c,v 1.44 2021/11/20 11:47:02 kn Exp $ */ 2 3 /* 4 * Copyright (c) 1995, 1996, 1997, 1998, 1999 5 * The Internet Software Consortium. 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 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of The Internet Software Consortium nor the names 17 * of its contributors may be used to endorse or promote products derived 18 * from this software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND 21 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 22 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 23 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 24 * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR 25 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 26 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 27 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 28 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 29 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * This software has been written for the Internet Software Consortium 35 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie 36 * Enterprises. To learn more about the Internet Software Consortium, 37 * see ``http://www.vix.com/isc''. To learn more about Vixie 38 * Enterprises, see ``http://www.vix.com''. 39 */ 40 41 #include <sys/types.h> 42 #include <sys/ioctl.h> 43 #include <sys/socket.h> 44 45 #include <arpa/inet.h> 46 47 #include <net/if.h> 48 #include <net/if_dl.h> 49 #include <net/if_media.h> 50 51 #include <netinet/in.h> 52 53 #include <errno.h> 54 #include <ifaddrs.h> 55 #include <limits.h> 56 #include <poll.h> 57 #include <stdio.h> 58 #include <stdlib.h> 59 #include <string.h> 60 #include <syslog.h> 61 #include <time.h> 62 #include <unistd.h> 63 64 #include "dhcp.h" 65 #include "tree.h" 66 #include "dhcpd.h" 67 #include "log.h" 68 #include "sync.h" 69 70 extern int syncfd; 71 72 struct interface_info *interfaces; 73 struct protocol *protocols; 74 struct dhcpd_timeout *timeouts; 75 static struct dhcpd_timeout *free_timeouts; 76 static int interfaces_invalidated; 77 78 static int interface_status(struct interface_info *ifinfo); 79 int get_rdomain(char *); 80 81 /* Use getifaddrs() to get a list of all the attached interfaces. 82 For each interface that's of type INET and not the loopback interface, 83 register that interface with the network I/O software, figure out what 84 subnet it's on, and add it to the list of interfaces. */ 85 86 void 87 discover_interfaces(int *rdomain) 88 { 89 struct interface_info *tmp; 90 struct interface_info *last, *next; 91 struct subnet *subnet; 92 struct shared_network *share; 93 struct sockaddr_in foo; 94 int ir = 0, ird; 95 struct ifreq *tif; 96 struct ifaddrs *ifap, *ifa; 97 98 if (getifaddrs(&ifap) != 0) 99 fatalx("getifaddrs failed"); 100 101 /* 102 * If we already have a list of interfaces, the interfaces were 103 * requested. 104 */ 105 if (interfaces != NULL) 106 ir = 1; 107 else 108 /* must specify an interface when rdomains are used */ 109 *rdomain = 0; 110 111 /* Cycle through the list of interfaces looking for IP addresses. */ 112 for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) { 113 /* 114 * See if this is the sort of interface we want to 115 * deal with. Skip loopback and point-to-point 116 * interfaces, except don't skip down interfaces if we're 117 * trying to get a list of configurable interfaces. 118 */ 119 if ((ifa->ifa_flags & IFF_LOOPBACK) || 120 (ifa->ifa_flags & IFF_POINTOPOINT) || 121 (!(ifa->ifa_flags & IFF_BROADCAST))) 122 continue; 123 124 /* See if we've seen an interface that matches this one. */ 125 for (tmp = interfaces; tmp; tmp = tmp->next) 126 if (!strcmp(tmp->name, ifa->ifa_name)) 127 break; 128 129 /* If we are looking for specific interfaces, ignore others. */ 130 if (tmp == NULL && ir) 131 continue; 132 133 ird = get_rdomain(ifa->ifa_name); 134 if (*rdomain == -1) 135 *rdomain = ird; 136 else if (*rdomain != ird && ir) 137 fatalx("Interface %s is not in rdomain %d", 138 tmp->name, *rdomain); 139 else if (*rdomain != ird && !ir) 140 continue; 141 142 /* If there isn't already an interface by this name, 143 allocate one. */ 144 if (tmp == NULL) { 145 tmp = calloc(1, sizeof *tmp); 146 if (!tmp) 147 fatalx("Insufficient memory to %s %s", 148 "record interface", ifa->ifa_name); 149 strlcpy(tmp->name, ifa->ifa_name, sizeof(tmp->name)); 150 tmp->next = interfaces; 151 tmp->noifmedia = tmp->dead = tmp->errors = 0; 152 interfaces = tmp; 153 } 154 155 /* If we have the capability, extract link information 156 and record it in a linked list. */ 157 if (ifa->ifa_addr->sa_family == AF_LINK) { 158 struct sockaddr_dl *sdl = 159 ((struct sockaddr_dl *)(ifa->ifa_addr)); 160 tmp->index = sdl->sdl_index; 161 tmp->hw_address.hlen = sdl->sdl_alen; 162 tmp->hw_address.htype = HTYPE_ETHER; /* XXX */ 163 memcpy(tmp->hw_address.haddr, 164 LLADDR(sdl), sdl->sdl_alen); 165 } else if (ifa->ifa_addr->sa_family == AF_INET) { 166 struct iaddr addr; 167 168 /* Get a pointer to the address... */ 169 memcpy(&foo, ifa->ifa_addr, sizeof(foo)); 170 171 /* We don't want the loopback interface. */ 172 if (foo.sin_addr.s_addr == htonl (INADDR_LOOPBACK)) 173 continue; 174 175 /* If this is the first real IP address we've 176 found, keep a pointer to ifreq structure in 177 which we found it. */ 178 if (!tmp->ifp) { 179 int len = (IFNAMSIZ + ifa->ifa_addr->sa_len); 180 tif = malloc(len); 181 if (!tif) 182 fatalx("no space to remember ifp."); 183 strlcpy(tif->ifr_name, ifa->ifa_name, 184 IFNAMSIZ); 185 memcpy(&tif->ifr_addr, ifa->ifa_addr, 186 ifa->ifa_addr->sa_len); 187 tmp->ifp = tif; 188 tmp->primary_address = foo.sin_addr; 189 } 190 191 /* Grab the address... */ 192 addr.len = 4; 193 memcpy(addr.iabuf, &foo.sin_addr.s_addr, addr.len); 194 195 /* If there's a registered subnet for this address, 196 connect it together... */ 197 if ((subnet = find_subnet(addr))) { 198 /* If this interface has multiple aliases 199 on the same subnet, ignore all but the 200 first we encounter. */ 201 if (!subnet->interface) { 202 subnet->interface = tmp; 203 subnet->interface_address = addr; 204 } else if (subnet->interface != tmp) { 205 log_warnx("Multiple %s %s: %s %s", 206 "interfaces match the", 207 "same subnet", 208 subnet->interface->name, 209 tmp->name); 210 } 211 share = subnet->shared_network; 212 if (tmp->shared_network && 213 tmp->shared_network != share) { 214 log_warnx("Interface %s matches %s", 215 tmp->name, 216 "multiple shared networks"); 217 } else { 218 tmp->shared_network = share; 219 } 220 221 if (!share->interface) { 222 share->interface = tmp; 223 } else if (share->interface != tmp) { 224 log_warnx("Multiple %s %s: %s %s", 225 "interfaces match the", 226 "same shared network", 227 share->interface->name, 228 tmp->name); 229 } 230 } 231 } 232 } 233 234 /* Discard interfaces we can't listen on. */ 235 last = NULL; 236 for (tmp = interfaces; tmp; tmp = next) { 237 next = tmp->next; 238 239 if (!tmp->ifp) { 240 log_warnx("Can't listen on %s - it has no IP address.", 241 tmp->name); 242 /* Remove tmp from the list of interfaces. */ 243 if (!last) 244 interfaces = interfaces->next; 245 else 246 last->next = tmp->next; 247 continue; 248 } 249 250 memcpy(&foo, &tmp->ifp->ifr_addr, sizeof tmp->ifp->ifr_addr); 251 252 if (!tmp->shared_network) { 253 log_warnx("Can't listen on %s - dhcpd.conf has no " 254 "subnet declaration for %s.", tmp->name, 255 inet_ntoa(foo.sin_addr)); 256 /* Remove tmp from the list of interfaces. */ 257 if (!last) 258 interfaces = interfaces->next; 259 else 260 last->next = tmp->next; 261 continue; 262 } 263 264 last = tmp; 265 266 /* Find subnets that don't have valid interface addresses. */ 267 for (subnet = (tmp->shared_network ? 268 tmp->shared_network->subnets : NULL); subnet; 269 subnet = subnet->next_sibling) { 270 if (!subnet->interface_address.len) { 271 /* 272 * Set the interface address for this subnet 273 * to the first address we found. 274 */ 275 subnet->interface_address.len = 4; 276 memcpy(subnet->interface_address.iabuf, 277 &foo.sin_addr.s_addr, 4); 278 } 279 } 280 281 /* Register the interface... */ 282 if_register_receive(tmp); 283 if_register_send(tmp); 284 log_info("Listening on %s (%s).", tmp->name, 285 inet_ntoa(foo.sin_addr)); 286 } 287 288 if (interfaces == NULL) 289 fatalx("No interfaces to listen on."); 290 291 /* Now register all the remaining interfaces as protocols. */ 292 for (tmp = interfaces; tmp; tmp = tmp->next) 293 add_protocol(tmp->name, tmp->rfdesc, got_one, tmp); 294 295 freeifaddrs(ifap); 296 } 297 298 /* 299 * Wait for packets to come in using poll(). When a packet comes in, 300 * call receive_packet to receive the packet and possibly strip hardware 301 * addressing information from it, and then process it in do_packet. 302 */ 303 void 304 dispatch(void) 305 { 306 int nfds, i, to_msec; 307 struct protocol *l; 308 static struct pollfd *fds; 309 static int nfds_max; 310 time_t howlong; 311 312 for (nfds = 0, l = protocols; l; l = l->next) 313 nfds++; 314 if (syncfd != -1) 315 nfds++; 316 if (nfds > nfds_max) { 317 fds = reallocarray(fds, nfds, sizeof(struct pollfd)); 318 if (fds == NULL) 319 fatalx("Can't allocate poll structures."); 320 nfds_max = nfds; 321 } 322 323 for (;;) { 324 /* 325 * Call any expired timeouts, and then if there's 326 * still a timeout registered, time out the poll 327 * call then. 328 */ 329 time(&cur_time); 330 another: 331 if (timeouts) { 332 if (timeouts->when <= cur_time) { 333 struct dhcpd_timeout *t = timeouts; 334 timeouts = timeouts->next; 335 (*(t->func))(t->what); 336 t->next = free_timeouts; 337 free_timeouts = t; 338 goto another; 339 } 340 341 /* 342 * Figure timeout in milliseconds, and check for 343 * potential overflow, so we can cram into an int 344 * for poll, while not polling with a negative 345 * timeout and blocking indefinitely. 346 */ 347 howlong = timeouts->when - cur_time; 348 if (howlong > INT_MAX / 1000) 349 howlong = INT_MAX / 1000; 350 to_msec = howlong * 1000; 351 } else 352 to_msec = -1; 353 354 /* Set up the descriptors to be polled. */ 355 for (i = 0, l = protocols; l; l = l->next) { 356 struct interface_info *ip = l->local; 357 358 if (ip && (l->handler != got_one || !ip->dead)) { 359 fds[i].fd = l->fd; 360 fds[i].events = POLLIN; 361 ++i; 362 } 363 } 364 365 if (i == 0) 366 fatalx("No live interfaces to poll on - exiting."); 367 368 if (syncfd != -1) { 369 /* add syncer */ 370 fds[i].fd = syncfd; 371 fds[i].events = POLLIN; 372 } 373 374 /* Wait for a packet or a timeout... */ 375 switch (poll(fds, nfds, to_msec)) { 376 case -1: 377 if (errno != EAGAIN && errno != EINTR) 378 fatal("poll"); 379 /* FALLTHROUGH */ 380 case 0: 381 continue; /* no packets */ 382 } 383 time(&cur_time); 384 385 for (i = 0, l = protocols; l; l = l->next) { 386 struct interface_info *ip = l->local; 387 388 if ((fds[i].revents & (POLLIN | POLLHUP))) { 389 if (ip && (l->handler != got_one || 390 !ip->dead)) 391 (*(l->handler))(l); 392 if (interfaces_invalidated) 393 break; 394 } 395 ++i; 396 } 397 if ((syncfd != -1) && (fds[i].revents & (POLLIN | POLLHUP))) 398 sync_recv(); 399 interfaces_invalidated = 0; 400 } 401 } 402 403 404 void 405 got_one(struct protocol *l) 406 { 407 struct sockaddr_in from; 408 struct hardware hfrom; 409 struct iaddr ifrom; 410 ssize_t result; 411 union { 412 unsigned char packbuf[4095]; 413 struct dhcp_packet packet; 414 } u; 415 struct interface_info *ip = l->local; 416 417 memset(&u, 0, sizeof(u)); 418 419 if ((result = receive_packet(ip, u.packbuf, sizeof u, 420 &from, &hfrom)) == -1) { 421 log_warn("receive_packet failed on %s", ip->name); 422 ip->errors++; 423 if ((!interface_status(ip)) || 424 (ip->noifmedia && ip->errors > 20)) { 425 /* our interface has gone away. */ 426 log_warnx("Interface %s no longer appears valid.", 427 ip->name); 428 ip->dead = 1; 429 interfaces_invalidated = 1; 430 close(l->fd); 431 remove_protocol(l); 432 free(ip); 433 } 434 return; 435 } 436 if (result == 0) 437 return; 438 439 ifrom.len = 4; 440 memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len); 441 442 do_packet(ip, &u.packet, result, from.sin_port, ifrom, &hfrom); 443 } 444 445 int 446 interface_status(struct interface_info *ifinfo) 447 { 448 char * ifname = ifinfo->name; 449 int ifsock = ifinfo->rfdesc; 450 struct ifreq ifr; 451 struct ifmediareq ifmr; 452 453 /* get interface flags */ 454 memset(&ifr, 0, sizeof(ifr)); 455 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 456 if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) == -1) { 457 log_warn("ioctl(SIOCGIFFLAGS) on %s", ifname); 458 goto inactive; 459 } 460 /* 461 * if one of UP and RUNNING flags is dropped, 462 * the interface is not active. 463 */ 464 if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) 465 goto inactive; 466 467 /* Next, check carrier on the interface, if possible */ 468 if (ifinfo->noifmedia) 469 goto active; 470 memset(&ifmr, 0, sizeof(ifmr)); 471 strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name)); 472 if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) { 473 if (errno != EINVAL) { 474 log_debug("ioctl(SIOCGIFMEDIA) on %s", ifname); 475 ifinfo->noifmedia = 1; 476 goto active; 477 } 478 /* 479 * EINVAL (or ENOTTY) simply means that the interface 480 * does not support the SIOCGIFMEDIA ioctl. We regard it alive. 481 */ 482 ifinfo->noifmedia = 1; 483 goto active; 484 } 485 if (ifmr.ifm_status & IFM_AVALID) { 486 switch (ifmr.ifm_active & IFM_NMASK) { 487 case IFM_ETHER: 488 if (ifmr.ifm_status & IFM_ACTIVE) 489 goto active; 490 else 491 goto inactive; 492 break; 493 default: 494 goto inactive; 495 } 496 } 497 inactive: 498 return (0); 499 active: 500 return (1); 501 } 502 503 int 504 locate_network(struct packet *packet) 505 { 506 struct iaddr ia; 507 508 /* If this came through a gateway, find the corresponding subnet... */ 509 if (packet->raw->giaddr.s_addr) { 510 struct subnet *subnet; 511 512 ia.len = 4; 513 memcpy(ia.iabuf, &packet->raw->giaddr, 4); 514 subnet = find_subnet(ia); 515 if (subnet) 516 packet->shared_network = subnet->shared_network; 517 else 518 packet->shared_network = NULL; 519 } else { 520 packet->shared_network = packet->interface->shared_network; 521 } 522 if (packet->shared_network) 523 return 1; 524 return 0; 525 } 526 527 void 528 add_timeout(time_t when, void (*where)(void *), void *what) 529 { 530 struct dhcpd_timeout *t, *q; 531 532 /* See if this timeout supersedes an existing timeout. */ 533 t = NULL; 534 for (q = timeouts; q; q = q->next) { 535 if (q->func == where && q->what == what) { 536 if (t) 537 t->next = q->next; 538 else 539 timeouts = q->next; 540 break; 541 } 542 t = q; 543 } 544 545 /* If we didn't supersede a timeout, allocate a timeout 546 structure now. */ 547 if (!q) { 548 if (free_timeouts) { 549 q = free_timeouts; 550 free_timeouts = q->next; 551 q->func = where; 552 q->what = what; 553 } else { 554 q = malloc(sizeof (struct dhcpd_timeout)); 555 if (!q) 556 fatalx("Can't allocate timeout structure!"); 557 q->func = where; 558 q->what = what; 559 } 560 } 561 562 q->when = when; 563 564 /* Now sort this timeout into the timeout list. */ 565 566 /* Beginning of list? */ 567 if (!timeouts || timeouts->when > q->when) { 568 q->next = timeouts; 569 timeouts = q; 570 return; 571 } 572 573 /* Middle of list? */ 574 for (t = timeouts; t->next; t = t->next) { 575 if (t->next->when > q->when) { 576 q->next = t->next; 577 t->next = q; 578 return; 579 } 580 } 581 582 /* End of list. */ 583 t->next = q; 584 q->next = NULL; 585 } 586 587 void 588 cancel_timeout(void (*where)(void *), void *what) 589 { 590 struct dhcpd_timeout *t, *q; 591 592 /* Look for this timeout on the list, and unlink it if we find it. */ 593 t = NULL; 594 for (q = timeouts; q; q = q->next) { 595 if (q->func == where && q->what == what) { 596 if (t) 597 t->next = q->next; 598 else 599 timeouts = q->next; 600 break; 601 } 602 t = q; 603 } 604 605 /* If we found the timeout, put it on the free list. */ 606 if (q) { 607 q->next = free_timeouts; 608 free_timeouts = q; 609 } 610 } 611 612 /* Add a protocol to the list of protocols... */ 613 void 614 add_protocol(char *name, int fd, void (*handler)(struct protocol *), 615 void *local) 616 { 617 struct protocol *p; 618 619 p = malloc(sizeof *p); 620 if (!p) 621 fatalx("can't allocate protocol struct for %s", name); 622 p->fd = fd; 623 p->handler = handler; 624 p->local = local; 625 p->next = protocols; 626 protocols = p; 627 } 628 629 void 630 remove_protocol(struct protocol *proto) 631 { 632 struct protocol *p, *next, *prev = NULL; 633 634 for (p = protocols; p; p = next) { 635 next = p->next; 636 if (p == proto) { 637 if (prev) 638 prev->next = p->next; 639 else 640 protocols = p->next; 641 free(p); 642 } 643 } 644 } 645 646 int 647 get_rdomain(char *name) 648 { 649 int rv = 0, s; 650 struct ifreq ifr; 651 652 if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1) 653 fatal("get_rdomain socket"); 654 655 memset(&ifr, 0, sizeof(ifr)); 656 strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name)); 657 if (ioctl(s, SIOCGIFRDOMAIN, (caddr_t)&ifr) != -1) 658 rv = ifr.ifr_rdomainid; 659 660 close(s); 661 return rv; 662 } 663