1 /* $OpenBSD: dispatch.c,v 1.43 2017/04/12 19:17:30 krw 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, point-to-point and down 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_UP)) || 122 (!(ifa->ifa_flags & IFF_BROADCAST))) 123 continue; 124 125 /* See if we've seen an interface that matches this one. */ 126 for (tmp = interfaces; tmp; tmp = tmp->next) 127 if (!strcmp(tmp->name, ifa->ifa_name)) 128 break; 129 130 /* If we are looking for specific interfaces, ignore others. */ 131 if (tmp == NULL && ir) 132 continue; 133 134 ird = get_rdomain(ifa->ifa_name); 135 if (*rdomain == -1) 136 *rdomain = ird; 137 else if (*rdomain != ird && ir) 138 fatalx("Interface %s is not in rdomain %d", 139 tmp->name, *rdomain); 140 else if (*rdomain != ird && !ir) 141 continue; 142 143 /* If there isn't already an interface by this name, 144 allocate one. */ 145 if (tmp == NULL) { 146 tmp = calloc(1, sizeof *tmp); 147 if (!tmp) 148 fatalx("Insufficient memory to %s %s", 149 "record interface", ifa->ifa_name); 150 strlcpy(tmp->name, ifa->ifa_name, sizeof(tmp->name)); 151 tmp->next = interfaces; 152 tmp->noifmedia = tmp->dead = tmp->errors = 0; 153 interfaces = tmp; 154 } 155 156 /* If we have the capability, extract link information 157 and record it in a linked list. */ 158 if (ifa->ifa_addr->sa_family == AF_LINK) { 159 struct sockaddr_dl *sdl = 160 ((struct sockaddr_dl *)(ifa->ifa_addr)); 161 tmp->index = sdl->sdl_index; 162 tmp->hw_address.hlen = sdl->sdl_alen; 163 tmp->hw_address.htype = HTYPE_ETHER; /* XXX */ 164 memcpy(tmp->hw_address.haddr, 165 LLADDR(sdl), sdl->sdl_alen); 166 } else if (ifa->ifa_addr->sa_family == AF_INET) { 167 struct iaddr addr; 168 169 /* Get a pointer to the address... */ 170 memcpy(&foo, ifa->ifa_addr, sizeof(foo)); 171 172 /* We don't want the loopback interface. */ 173 if (foo.sin_addr.s_addr == htonl (INADDR_LOOPBACK)) 174 continue; 175 176 /* If this is the first real IP address we've 177 found, keep a pointer to ifreq structure in 178 which we found it. */ 179 if (!tmp->ifp) { 180 int len = (IFNAMSIZ + ifa->ifa_addr->sa_len); 181 tif = malloc(len); 182 if (!tif) 183 fatalx("no space to remember ifp."); 184 strlcpy(tif->ifr_name, ifa->ifa_name, 185 IFNAMSIZ); 186 memcpy(&tif->ifr_addr, ifa->ifa_addr, 187 ifa->ifa_addr->sa_len); 188 tmp->ifp = tif; 189 tmp->primary_address = foo.sin_addr; 190 } 191 192 /* Grab the address... */ 193 addr.len = 4; 194 memcpy(addr.iabuf, &foo.sin_addr.s_addr, addr.len); 195 196 /* If there's a registered subnet for this address, 197 connect it together... */ 198 if ((subnet = find_subnet(addr))) { 199 /* If this interface has multiple aliases 200 on the same subnet, ignore all but the 201 first we encounter. */ 202 if (!subnet->interface) { 203 subnet->interface = tmp; 204 subnet->interface_address = addr; 205 } else if (subnet->interface != tmp) { 206 log_warnx("Multiple %s %s: %s %s", 207 "interfaces match the", 208 "same subnet", 209 subnet->interface->name, 210 tmp->name); 211 } 212 share = subnet->shared_network; 213 if (tmp->shared_network && 214 tmp->shared_network != share) { 215 log_warnx("Interface %s matches %s", 216 tmp->name, 217 "multiple shared networks"); 218 } else { 219 tmp->shared_network = share; 220 } 221 222 if (!share->interface) { 223 share->interface = tmp; 224 } else if (share->interface != tmp) { 225 log_warnx("Multiple %s %s: %s %s", 226 "interfaces match the", 227 "same shared network", 228 share->interface->name, 229 tmp->name); 230 } 231 } 232 } 233 } 234 235 /* Discard interfaces we can't listen on. */ 236 last = NULL; 237 for (tmp = interfaces; tmp; tmp = next) { 238 next = tmp->next; 239 240 if (!tmp->ifp) { 241 log_warnx("Can't listen on %s - it has no IP address.", 242 tmp->name); 243 /* Remove tmp from the list of interfaces. */ 244 if (!last) 245 interfaces = interfaces->next; 246 else 247 last->next = tmp->next; 248 continue; 249 } 250 251 memcpy(&foo, &tmp->ifp->ifr_addr, sizeof tmp->ifp->ifr_addr); 252 253 if (!tmp->shared_network) { 254 log_warnx("Can't listen on %s - dhcpd.conf has no " 255 "subnet declaration for %s.", tmp->name, 256 inet_ntoa(foo.sin_addr)); 257 /* Remove tmp from the list of interfaces. */ 258 if (!last) 259 interfaces = interfaces->next; 260 else 261 last->next = tmp->next; 262 continue; 263 } 264 265 last = tmp; 266 267 /* Find subnets that don't have valid interface addresses. */ 268 for (subnet = (tmp->shared_network ? 269 tmp->shared_network->subnets : NULL); subnet; 270 subnet = subnet->next_sibling) { 271 if (!subnet->interface_address.len) { 272 /* 273 * Set the interface address for this subnet 274 * to the first address we found. 275 */ 276 subnet->interface_address.len = 4; 277 memcpy(subnet->interface_address.iabuf, 278 &foo.sin_addr.s_addr, 4); 279 } 280 } 281 282 /* Register the interface... */ 283 if_register_receive(tmp); 284 if_register_send(tmp); 285 log_info("Listening on %s (%s).", tmp->name, 286 inet_ntoa(foo.sin_addr)); 287 } 288 289 if (interfaces == NULL) 290 fatalx("No interfaces to listen on."); 291 292 /* Now register all the remaining interfaces as protocols. */ 293 for (tmp = interfaces; tmp; tmp = tmp->next) 294 add_protocol(tmp->name, tmp->rfdesc, got_one, tmp); 295 296 freeifaddrs(ifap); 297 } 298 299 /* 300 * Wait for packets to come in using poll(). When a packet comes in, 301 * call receive_packet to receive the packet and possibly strip hardware 302 * addressing information from it, and then process it in do_packet. 303 */ 304 void 305 dispatch(void) 306 { 307 int nfds, i, to_msec; 308 struct protocol *l; 309 static struct pollfd *fds; 310 static int nfds_max; 311 time_t howlong; 312 313 for (nfds = 0, l = protocols; l; l = l->next) 314 nfds++; 315 if (syncfd != -1) 316 nfds++; 317 if (nfds > nfds_max) { 318 fds = reallocarray(fds, nfds, sizeof(struct pollfd)); 319 if (fds == NULL) 320 fatalx("Can't allocate poll structures."); 321 nfds_max = nfds; 322 } 323 324 for (;;) { 325 /* 326 * Call any expired timeouts, and then if there's 327 * still a timeout registered, time out the poll 328 * call then. 329 */ 330 time(&cur_time); 331 another: 332 if (timeouts) { 333 if (timeouts->when <= cur_time) { 334 struct dhcpd_timeout *t = timeouts; 335 timeouts = timeouts->next; 336 (*(t->func))(t->what); 337 t->next = free_timeouts; 338 free_timeouts = t; 339 goto another; 340 } 341 342 /* 343 * Figure timeout in milliseconds, and check for 344 * potential overflow, so we can cram into an int 345 * for poll, while not polling with a negative 346 * timeout and blocking indefinitely. 347 */ 348 howlong = timeouts->when - cur_time; 349 if (howlong > INT_MAX / 1000) 350 howlong = INT_MAX / 1000; 351 to_msec = howlong * 1000; 352 } else 353 to_msec = -1; 354 355 /* Set up the descriptors to be polled. */ 356 for (i = 0, l = protocols; l; l = l->next) { 357 struct interface_info *ip = l->local; 358 359 if (ip && (l->handler != got_one || !ip->dead)) { 360 fds[i].fd = l->fd; 361 fds[i].events = POLLIN; 362 ++i; 363 } 364 } 365 366 if (i == 0) 367 fatalx("No live interfaces to poll on - exiting."); 368 369 if (syncfd != -1) { 370 /* add syncer */ 371 fds[i].fd = syncfd; 372 fds[i].events = POLLIN; 373 } 374 375 /* Wait for a packet or a timeout... */ 376 switch (poll(fds, nfds, to_msec)) { 377 case -1: 378 if (errno != EAGAIN && errno != EINTR) 379 fatal("poll"); 380 /* FALLTHROUGH */ 381 case 0: 382 continue; /* no packets */ 383 } 384 time(&cur_time); 385 386 for (i = 0, l = protocols; l; l = l->next) { 387 struct interface_info *ip = l->local; 388 389 if ((fds[i].revents & (POLLIN | POLLHUP))) { 390 if (ip && (l->handler != got_one || 391 !ip->dead)) 392 (*(l->handler))(l); 393 if (interfaces_invalidated) 394 break; 395 } 396 ++i; 397 } 398 if ((syncfd != -1) && (fds[i].revents & (POLLIN | POLLHUP))) 399 sync_recv(); 400 interfaces_invalidated = 0; 401 } 402 } 403 404 405 void 406 got_one(struct protocol *l) 407 { 408 struct sockaddr_in from; 409 struct hardware hfrom; 410 struct iaddr ifrom; 411 ssize_t result; 412 union { 413 unsigned char packbuf[4095]; 414 struct dhcp_packet packet; 415 } u; 416 struct interface_info *ip = l->local; 417 418 memset(&u, 0, sizeof(u)); 419 420 if ((result = receive_packet(ip, u.packbuf, sizeof u, 421 &from, &hfrom)) == -1) { 422 log_warn("receive_packet failed on %s", ip->name); 423 ip->errors++; 424 if ((!interface_status(ip)) || 425 (ip->noifmedia && ip->errors > 20)) { 426 /* our interface has gone away. */ 427 log_warnx("Interface %s no longer appears valid.", 428 ip->name); 429 ip->dead = 1; 430 interfaces_invalidated = 1; 431 close(l->fd); 432 remove_protocol(l); 433 free(ip); 434 } 435 return; 436 } 437 if (result == 0) 438 return; 439 440 ifrom.len = 4; 441 memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len); 442 443 do_packet(ip, &u.packet, result, from.sin_port, ifrom, &hfrom); 444 } 445 446 int 447 interface_status(struct interface_info *ifinfo) 448 { 449 char * ifname = ifinfo->name; 450 int ifsock = ifinfo->rfdesc; 451 struct ifreq ifr; 452 struct ifmediareq ifmr; 453 454 /* get interface flags */ 455 memset(&ifr, 0, sizeof(ifr)); 456 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 457 if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) == -1) { 458 log_warn("ioctl(SIOCGIFFLAGS) on %s", ifname); 459 goto inactive; 460 } 461 /* 462 * if one of UP and RUNNING flags is dropped, 463 * the interface is not active. 464 */ 465 if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) 466 goto inactive; 467 468 /* Next, check carrier on the interface, if possible */ 469 if (ifinfo->noifmedia) 470 goto active; 471 memset(&ifmr, 0, sizeof(ifmr)); 472 strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name)); 473 if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) { 474 if (errno != EINVAL) { 475 log_debug("ioctl(SIOCGIFMEDIA) on %s", ifname); 476 ifinfo->noifmedia = 1; 477 goto active; 478 } 479 /* 480 * EINVAL (or ENOTTY) simply means that the interface 481 * does not support the SIOCGIFMEDIA ioctl. We regard it alive. 482 */ 483 ifinfo->noifmedia = 1; 484 goto active; 485 } 486 if (ifmr.ifm_status & IFM_AVALID) { 487 switch (ifmr.ifm_active & IFM_NMASK) { 488 case IFM_ETHER: 489 if (ifmr.ifm_status & IFM_ACTIVE) 490 goto active; 491 else 492 goto inactive; 493 break; 494 default: 495 goto inactive; 496 } 497 } 498 inactive: 499 return (0); 500 active: 501 return (1); 502 } 503 504 int 505 locate_network(struct packet *packet) 506 { 507 struct iaddr ia; 508 509 /* If this came through a gateway, find the corresponding subnet... */ 510 if (packet->raw->giaddr.s_addr) { 511 struct subnet *subnet; 512 513 ia.len = 4; 514 memcpy(ia.iabuf, &packet->raw->giaddr, 4); 515 subnet = find_subnet(ia); 516 if (subnet) 517 packet->shared_network = subnet->shared_network; 518 else 519 packet->shared_network = NULL; 520 } else { 521 packet->shared_network = packet->interface->shared_network; 522 } 523 if (packet->shared_network) 524 return 1; 525 return 0; 526 } 527 528 void 529 add_timeout(time_t when, void (*where)(void *), void *what) 530 { 531 struct dhcpd_timeout *t, *q; 532 533 /* See if this timeout supersedes an existing timeout. */ 534 t = NULL; 535 for (q = timeouts; q; q = q->next) { 536 if (q->func == where && q->what == what) { 537 if (t) 538 t->next = q->next; 539 else 540 timeouts = q->next; 541 break; 542 } 543 t = q; 544 } 545 546 /* If we didn't supersede a timeout, allocate a timeout 547 structure now. */ 548 if (!q) { 549 if (free_timeouts) { 550 q = free_timeouts; 551 free_timeouts = q->next; 552 q->func = where; 553 q->what = what; 554 } else { 555 q = malloc(sizeof (struct dhcpd_timeout)); 556 if (!q) 557 fatalx("Can't allocate timeout structure!"); 558 q->func = where; 559 q->what = what; 560 } 561 } 562 563 q->when = when; 564 565 /* Now sort this timeout into the timeout list. */ 566 567 /* Beginning of list? */ 568 if (!timeouts || timeouts->when > q->when) { 569 q->next = timeouts; 570 timeouts = q; 571 return; 572 } 573 574 /* Middle of list? */ 575 for (t = timeouts; t->next; t = t->next) { 576 if (t->next->when > q->when) { 577 q->next = t->next; 578 t->next = q; 579 return; 580 } 581 } 582 583 /* End of list. */ 584 t->next = q; 585 q->next = NULL; 586 } 587 588 void 589 cancel_timeout(void (*where)(void *), void *what) 590 { 591 struct dhcpd_timeout *t, *q; 592 593 /* Look for this timeout on the list, and unlink it if we find it. */ 594 t = NULL; 595 for (q = timeouts; q; q = q->next) { 596 if (q->func == where && q->what == what) { 597 if (t) 598 t->next = q->next; 599 else 600 timeouts = q->next; 601 break; 602 } 603 t = q; 604 } 605 606 /* If we found the timeout, put it on the free list. */ 607 if (q) { 608 q->next = free_timeouts; 609 free_timeouts = q; 610 } 611 } 612 613 /* Add a protocol to the list of protocols... */ 614 void 615 add_protocol(char *name, int fd, void (*handler)(struct protocol *), 616 void *local) 617 { 618 struct protocol *p; 619 620 p = malloc(sizeof *p); 621 if (!p) 622 fatalx("can't allocate protocol struct for %s", name); 623 p->fd = fd; 624 p->handler = handler; 625 p->local = local; 626 p->next = protocols; 627 protocols = p; 628 } 629 630 void 631 remove_protocol(struct protocol *proto) 632 { 633 struct protocol *p, *next, *prev = NULL; 634 635 for (p = protocols; p; p = next) { 636 next = p->next; 637 if (p == proto) { 638 if (prev) 639 prev->next = p->next; 640 else 641 protocols = p->next; 642 free(p); 643 } 644 } 645 } 646 647 int 648 get_rdomain(char *name) 649 { 650 int rv = 0, s; 651 struct ifreq ifr; 652 653 if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1) 654 fatal("get_rdomain socket"); 655 656 memset(&ifr, 0, sizeof(ifr)); 657 strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name)); 658 if (ioctl(s, SIOCGIFRDOMAIN, (caddr_t)&ifr) != -1) 659 rv = ifr.ifr_rdomainid; 660 661 close(s); 662 return rv; 663 } 664