1 /* $OpenBSD: dispatch.c,v 1.37 2016/08/27 01:26:22 guenther 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 "sync.h" 68 69 extern int syncfd; 70 71 struct interface_info *interfaces; 72 struct protocol *protocols; 73 struct dhcpd_timeout *timeouts; 74 static struct dhcpd_timeout *free_timeouts; 75 static int interfaces_invalidated; 76 77 static int interface_status(struct interface_info *ifinfo); 78 int get_rdomain(char *); 79 80 /* Use getifaddrs() to get a list of all the attached interfaces. 81 For each interface that's of type INET and not the loopback interface, 82 register that interface with the network I/O software, figure out what 83 subnet it's on, and add it to the list of interfaces. */ 84 85 void 86 discover_interfaces(int *rdomain) 87 { 88 struct interface_info *tmp; 89 struct interface_info *last, *next; 90 struct subnet *subnet; 91 struct shared_network *share; 92 struct sockaddr_in foo; 93 int ir = 0, ird; 94 struct ifreq *tif; 95 struct ifaddrs *ifap, *ifa; 96 97 if (getifaddrs(&ifap) != 0) 98 error("getifaddrs failed"); 99 100 /* 101 * If we already have a list of interfaces, the interfaces were 102 * requested. 103 */ 104 if (interfaces != NULL) 105 ir = 1; 106 else 107 /* must specify an interface when rdomains are used */ 108 *rdomain = 0; 109 110 /* Cycle through the list of interfaces looking for IP addresses. */ 111 for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) { 112 /* 113 * See if this is the sort of interface we want to 114 * deal with. Skip loopback, point-to-point and down 115 * interfaces, except don't skip down interfaces if we're 116 * trying to get a list of configurable interfaces. 117 */ 118 if ((ifa->ifa_flags & IFF_LOOPBACK) || 119 (ifa->ifa_flags & IFF_POINTOPOINT) || 120 (!(ifa->ifa_flags & IFF_UP)) || 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 error("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 error("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 *foo = 159 ((struct sockaddr_dl *)(ifa->ifa_addr)); 160 tmp->index = foo->sdl_index; 161 tmp->hw_address.hlen = foo->sdl_alen; 162 tmp->hw_address.htype = HTYPE_ETHER; /* XXX */ 163 memcpy(tmp->hw_address.haddr, 164 LLADDR(foo), foo->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 error("no space to remember ifp."); 183 strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ); 184 memcpy(&tif->ifr_addr, ifa->ifa_addr, 185 ifa->ifa_addr->sa_len); 186 tmp->ifp = tif; 187 tmp->primary_address = foo.sin_addr; 188 } 189 190 /* Grab the address... */ 191 addr.len = 4; 192 memcpy(addr.iabuf, &foo.sin_addr.s_addr, addr.len); 193 194 /* If there's a registered subnet for this address, 195 connect it together... */ 196 if ((subnet = find_subnet(addr))) { 197 /* If this interface has multiple aliases 198 on the same subnet, ignore all but the 199 first we encounter. */ 200 if (!subnet->interface) { 201 subnet->interface = tmp; 202 subnet->interface_address = addr; 203 } else if (subnet->interface != tmp) { 204 warning("Multiple %s %s: %s %s", 205 "interfaces match the", 206 "same subnet", 207 subnet->interface->name, 208 tmp->name); 209 } 210 share = subnet->shared_network; 211 if (tmp->shared_network && 212 tmp->shared_network != share) { 213 warning("Interface %s matches %s", 214 tmp->name, 215 "multiple shared networks"); 216 } else { 217 tmp->shared_network = share; 218 } 219 220 if (!share->interface) { 221 share->interface = tmp; 222 } else if (share->interface != tmp) { 223 warning("Multiple %s %s: %s %s", 224 "interfaces match the", 225 "same shared network", 226 share->interface->name, 227 tmp->name); 228 } 229 } 230 } 231 } 232 233 /* Discard interfaces we can't listen on. */ 234 last = NULL; 235 for (tmp = interfaces; tmp; tmp = next) { 236 next = tmp->next; 237 238 if (!tmp->ifp) { 239 warning("Can't listen on %s - it has no IP address.", 240 tmp->name); 241 /* Remove tmp from the list of interfaces. */ 242 if (!last) 243 interfaces = interfaces->next; 244 else 245 last->next = tmp->next; 246 continue; 247 } 248 249 memcpy(&foo, &tmp->ifp->ifr_addr, sizeof tmp->ifp->ifr_addr); 250 251 if (!tmp->shared_network) { 252 warning("Can't listen on %s - dhcpd.conf has no subnet " 253 "declaration for %s.", tmp->name, 254 inet_ntoa(foo.sin_addr)); 255 /* Remove tmp from the list of interfaces. */ 256 if (!last) 257 interfaces = interfaces->next; 258 else 259 last->next = tmp->next; 260 continue; 261 } 262 263 last = tmp; 264 265 /* Find subnets that don't have valid interface addresses. */ 266 for (subnet = (tmp->shared_network ? tmp->shared_network->subnets : 267 NULL); subnet; subnet = subnet->next_sibling) { 268 if (!subnet->interface_address.len) { 269 /* 270 * Set the interface address for this subnet 271 * to the first address we found. 272 */ 273 subnet->interface_address.len = 4; 274 memcpy(subnet->interface_address.iabuf, 275 &foo.sin_addr.s_addr, 4); 276 } 277 } 278 279 /* Register the interface... */ 280 if_register_receive(tmp); 281 if_register_send(tmp); 282 note("Listening on %s (%s).", tmp->name, 283 inet_ntoa(foo.sin_addr)); 284 } 285 286 if (interfaces == NULL) 287 error("No interfaces to listen on."); 288 289 /* Now register all the remaining interfaces as protocols. */ 290 for (tmp = interfaces; tmp; tmp = tmp->next) 291 add_protocol(tmp->name, tmp->rfdesc, got_one, tmp); 292 293 freeifaddrs(ifap); 294 } 295 296 /* 297 * Wait for packets to come in using poll(). When a packet comes in, 298 * call receive_packet to receive the packet and possibly strip hardware 299 * addressing information from it, and then process it in do_packet. 300 */ 301 void 302 dispatch(void) 303 { 304 int nfds, i, to_msec; 305 struct protocol *l; 306 static struct pollfd *fds; 307 static int nfds_max; 308 time_t howlong; 309 310 for (nfds = 0, l = protocols; l; l = l->next) 311 nfds++; 312 if (syncfd != -1) 313 nfds++; 314 if (nfds > nfds_max) { 315 fds = reallocarray(fds, nfds, sizeof(struct pollfd)); 316 if (fds == NULL) 317 error("Can't allocate poll structures."); 318 nfds_max = nfds; 319 } 320 321 for (;;) { 322 /* 323 * Call any expired timeouts, and then if there's 324 * still a timeout registered, time out the poll 325 * call then. 326 */ 327 time(&cur_time); 328 another: 329 if (timeouts) { 330 if (timeouts->when <= cur_time) { 331 struct dhcpd_timeout *t = timeouts; 332 timeouts = timeouts->next; 333 (*(t->func))(t->what); 334 t->next = free_timeouts; 335 free_timeouts = t; 336 goto another; 337 } 338 339 /* 340 * Figure timeout in milliseconds, and check for 341 * potential overflow, so we can cram into an int 342 * for poll, while not polling with a negative 343 * timeout and blocking indefinitely. 344 */ 345 howlong = timeouts->when - cur_time; 346 if (howlong > INT_MAX / 1000) 347 howlong = INT_MAX / 1000; 348 to_msec = howlong * 1000; 349 } else 350 to_msec = -1; 351 352 /* Set up the descriptors to be polled. */ 353 for (i = 0, l = protocols; l; l = l->next) { 354 struct interface_info *ip = l->local; 355 356 if (ip && (l->handler != got_one || !ip->dead)) { 357 fds[i].fd = l->fd; 358 fds[i].events = POLLIN; 359 ++i; 360 } 361 } 362 363 if (i == 0) 364 error("No live interfaces to poll on - exiting."); 365 366 if (syncfd != -1) { 367 /* add syncer */ 368 fds[i].fd = syncfd; 369 fds[i].events = POLLIN; 370 } 371 372 /* Wait for a packet or a timeout... */ 373 switch (poll(fds, nfds, to_msec)) { 374 case -1: 375 if (errno != EAGAIN && errno != EINTR) 376 error("poll: %m"); 377 /* FALLTHROUGH */ 378 case 0: 379 continue; /* no packets */ 380 } 381 time(&cur_time); 382 383 for (i = 0, l = protocols; l; l = l->next) { 384 struct interface_info *ip = l->local; 385 386 if ((fds[i].revents & (POLLIN | POLLHUP))) { 387 if (ip && (l->handler != got_one || 388 !ip->dead)) 389 (*(l->handler))(l); 390 if (interfaces_invalidated) 391 break; 392 } 393 ++i; 394 } 395 if ((syncfd != -1) && (fds[i].revents & (POLLIN | POLLHUP))) 396 sync_recv(); 397 interfaces_invalidated = 0; 398 } 399 } 400 401 402 void 403 got_one(struct protocol *l) 404 { 405 struct sockaddr_in from; 406 struct hardware hfrom; 407 struct iaddr ifrom; 408 ssize_t result; 409 union { 410 unsigned char packbuf[4095]; 411 struct dhcp_packet packet; 412 } u; 413 struct interface_info *ip = l->local; 414 415 bzero(&u, sizeof(u)); 416 417 if ((result = receive_packet(ip, u.packbuf, sizeof u, 418 &from, &hfrom)) == -1) { 419 warning("receive_packet failed on %s: %s", ip->name, 420 strerror(errno)); 421 ip->errors++; 422 if ((!interface_status(ip)) || 423 (ip->noifmedia && ip->errors > 20)) { 424 /* our interface has gone away. */ 425 warning("Interface %s no longer appears valid.", 426 ip->name); 427 ip->dead = 1; 428 interfaces_invalidated = 1; 429 close(l->fd); 430 remove_protocol(l); 431 free(ip); 432 } 433 return; 434 } 435 if (result == 0) 436 return; 437 438 ifrom.len = 4; 439 memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len); 440 441 do_packet(ip, &u.packet, result, from.sin_port, ifrom, &hfrom); 442 } 443 444 int 445 interface_status(struct interface_info *ifinfo) 446 { 447 char * ifname = ifinfo->name; 448 int ifsock = ifinfo->rfdesc; 449 struct ifreq ifr; 450 struct ifmediareq ifmr; 451 452 /* get interface flags */ 453 memset(&ifr, 0, sizeof(ifr)); 454 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 455 if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) == -1) { 456 syslog(LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m", ifname); 457 goto inactive; 458 } 459 /* 460 * if one of UP and RUNNING flags is dropped, 461 * the interface is not active. 462 */ 463 if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) 464 goto inactive; 465 466 /* Next, check carrier on the interface, if possible */ 467 if (ifinfo->noifmedia) 468 goto active; 469 memset(&ifmr, 0, sizeof(ifmr)); 470 strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name)); 471 if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) { 472 if (errno != EINVAL) { 473 syslog(LOG_DEBUG, "ioctl(SIOCGIFMEDIA) on %s: %m", 474 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 error("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 error("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 error("get_rdomain socket: %m"); 654 655 bzero(&ifr, 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