dispatch.c revision 1.22
1/* $OpenBSD: dispatch.c,v 1.22 2006/12/12 19:38:55 stevesk 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 "dhcpd.h" 42#include <ifaddrs.h> 43#include <sys/ioctl.h> 44#include <poll.h> 45#include <net/if_media.h> 46 47struct interface_info *interfaces; 48struct protocol *protocols; 49struct dhcpd_timeout *timeouts; 50static struct dhcpd_timeout *free_timeouts; 51static int interfaces_invalidated; 52void (*bootp_packet_handler)(struct interface_info *, 53 struct dhcp_packet *, int, unsigned int, struct iaddr, struct hardware *); 54 55static int interface_status(struct interface_info *ifinfo); 56 57/* Use getifaddrs() to get a list of all the attached interfaces. 58 For each interface that's of type INET and not the loopback interface, 59 register that interface with the network I/O software, figure out what 60 subnet it's on, and add it to the list of interfaces. */ 61 62void 63discover_interfaces(void) 64{ 65 struct interface_info *tmp; 66 struct interface_info *last, *next; 67 struct subnet *subnet; 68 struct shared_network *share; 69 struct sockaddr_in foo; 70 int ir = 0; 71 struct ifreq *tif; 72 struct ifaddrs *ifap, *ifa; 73 74 if (getifaddrs(&ifap) != 0) 75 error("getifaddrs failed"); 76 77 /* 78 * If we already have a list of interfaces, the interfaces were 79 * requested. 80 */ 81 if (interfaces != NULL) 82 ir = 1; 83 84 /* Cycle through the list of interfaces looking for IP addresses. */ 85 for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) { 86 /* 87 * See if this is the sort of interface we want to 88 * deal with. Skip loopback, point-to-point and down 89 * interfaces, except don't skip down interfaces if we're 90 * trying to get a list of configurable interfaces. 91 */ 92 if ((ifa->ifa_flags & IFF_LOOPBACK) || 93 (ifa->ifa_flags & IFF_POINTOPOINT) || 94 (!(ifa->ifa_flags & IFF_UP))) 95 continue; 96 97 /* See if we've seen an interface that matches this one. */ 98 for (tmp = interfaces; tmp; tmp = tmp->next) 99 if (!strcmp(tmp->name, ifa->ifa_name)) 100 break; 101 102 /* If we are looking for specific interfaces, ignore others. */ 103 if (tmp == NULL && ir) 104 continue; 105 106 /* If there isn't already an interface by this name, 107 allocate one. */ 108 if (tmp == NULL) { 109 tmp = ((struct interface_info *)dmalloc(sizeof *tmp, 110 "discover_interfaces")); 111 if (!tmp) 112 error("Insufficient memory to %s %s", 113 "record interface", ifa->ifa_name); 114 strlcpy(tmp->name, ifa->ifa_name, sizeof(tmp->name)); 115 tmp->next = interfaces; 116 tmp->noifmedia = tmp->dead = tmp->errors = 0; 117 interfaces = tmp; 118 } 119 120 /* If we have the capability, extract link information 121 and record it in a linked list. */ 122 if (ifa->ifa_addr->sa_family == AF_LINK) { 123 struct sockaddr_dl *foo = 124 ((struct sockaddr_dl *)(ifa->ifa_addr)); 125 tmp->index = foo->sdl_index; 126 tmp->hw_address.hlen = foo->sdl_alen; 127 tmp->hw_address.htype = HTYPE_ETHER; /* XXX */ 128 memcpy(tmp->hw_address.haddr, 129 LLADDR(foo), foo->sdl_alen); 130 } else if (ifa->ifa_addr->sa_family == AF_INET) { 131 struct iaddr addr; 132 133 /* Get a pointer to the address... */ 134 bcopy(ifa->ifa_addr, &foo, sizeof(foo)); 135 136 /* We don't want the loopback interface. */ 137 if (foo.sin_addr.s_addr == htonl (INADDR_LOOPBACK)) 138 continue; 139 140 /* If this is the first real IP address we've 141 found, keep a pointer to ifreq structure in 142 which we found it. */ 143 if (!tmp->ifp) { 144 int len = (IFNAMSIZ + ifa->ifa_addr->sa_len); 145 tif = (struct ifreq *)malloc(len); 146 if (!tif) 147 error("no space to remember ifp."); 148 strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ); 149 memcpy(&tif->ifr_addr, ifa->ifa_addr, 150 ifa->ifa_addr->sa_len); 151 tmp->ifp = tif; 152 tmp->primary_address = foo.sin_addr; 153 } 154 155 /* Grab the address... */ 156 addr.len = 4; 157 memcpy(addr.iabuf, &foo.sin_addr.s_addr, addr.len); 158 159 /* If there's a registered subnet for this address, 160 connect it together... */ 161 if ((subnet = find_subnet(addr))) { 162 /* If this interface has multiple aliases 163 on the same subnet, ignore all but the 164 first we encounter. */ 165 if (!subnet->interface) { 166 subnet->interface = tmp; 167 subnet->interface_address = addr; 168 } else if (subnet->interface != tmp) { 169 warning("Multiple %s %s: %s %s", 170 "interfaces match the", 171 "same subnet", 172 subnet->interface->name, 173 tmp->name); 174 } 175 share = subnet->shared_network; 176 if (tmp->shared_network && 177 tmp->shared_network != share) { 178 warning("Interface %s matches %s", 179 tmp->name, 180 "multiple shared networks"); 181 } else { 182 tmp->shared_network = share; 183 } 184 185 if (!share->interface) { 186 share->interface = tmp; 187 } else if (share->interface != tmp) { 188 warning("Multiple %s %s: %s %s", 189 "interfaces match the", 190 "same shared network", 191 share->interface->name, 192 tmp->name); 193 } 194 } 195 } 196 } 197 198 /* Discard interfaces we can't listen on. */ 199 last = NULL; 200 for (tmp = interfaces; tmp; tmp = next) { 201 next = tmp->next; 202 203 if (!tmp->ifp) { 204 warning("Can't listen on %s - it has no IP address.", 205 tmp->name); 206 /* Remove tmp from the list of interfaces. */ 207 if (!last) 208 interfaces = interfaces->next; 209 else 210 last->next = tmp->next; 211 continue; 212 } 213 214 memcpy(&foo, &tmp->ifp->ifr_addr, sizeof tmp->ifp->ifr_addr); 215 216 if (!tmp->shared_network) { 217 warning("Can't listen on %s - dhcpd.conf has no subnet " 218 "declaration for %s.", tmp->name, 219 inet_ntoa(foo.sin_addr)); 220 /* Remove tmp from the list of interfaces. */ 221 if (!last) 222 interfaces = interfaces->next; 223 else 224 last->next = tmp->next; 225 continue; 226 } 227 228 last = tmp; 229 230 /* Find subnets that don't have valid interface addresses. */ 231 for (subnet = (tmp->shared_network ? tmp->shared_network->subnets : 232 NULL); subnet; subnet = subnet->next_sibling) { 233 if (!subnet->interface_address.len) { 234 /* 235 * Set the interface address for this subnet 236 * to the first address we found. 237 */ 238 subnet->interface_address.len = 4; 239 memcpy(subnet->interface_address.iabuf, 240 &foo.sin_addr.s_addr, 4); 241 } 242 } 243 244 /* Register the interface... */ 245 if_register_receive(tmp); 246 if_register_send(tmp); 247 } 248 249 if (interfaces == NULL) 250 error("No interfaces to listen on."); 251 252 /* Now register all the remaining interfaces as protocols. */ 253 for (tmp = interfaces; tmp; tmp = tmp->next) 254 add_protocol(tmp->name, tmp->rfdesc, got_one, tmp); 255 256 freeifaddrs(ifap); 257} 258 259/* 260 * Wait for packets to come in using poll(). When a packet comes in, 261 * call receive_packet to receive the packet and possibly strip hardware 262 * addressing information from it, and then call through the 263 * bootp_packet_handler hook to try to do something with it. 264 */ 265void 266dispatch(void) 267{ 268 int nfds, i, to_msec; 269 struct protocol *l; 270 static struct pollfd *fds; 271 static int nfds_max; 272 time_t howlong; 273 274 for (nfds = 0, l = protocols; l; l = l->next) 275 nfds++; 276 if (nfds > nfds_max) { 277 fds = realloc(fds, nfds * sizeof(struct pollfd)); 278 if (fds == NULL) 279 error("Can't allocate poll structures."); 280 nfds_max = nfds; 281 } 282 283 for (;;) { 284 /* 285 * Call any expired timeouts, and then if there's 286 * still a timeout registered, time out the poll 287 * call then. 288 */ 289 time(&cur_time); 290another: 291 if (timeouts) { 292 if (timeouts->when <= cur_time) { 293 struct dhcpd_timeout *t = timeouts; 294 timeouts = timeouts->next; 295 (*(t->func))(t->what); 296 t->next = free_timeouts; 297 free_timeouts = t; 298 goto another; 299 } 300 301 /* 302 * Figure timeout in milliseconds, and check for 303 * potential overflow, so we can cram into an int 304 * for poll, while not polling with a negative 305 * timeout and blocking indefinitely. 306 */ 307 howlong = timeouts->when - cur_time; 308 if (howlong > INT_MAX / 1000) 309 howlong = INT_MAX / 1000; 310 to_msec = howlong * 1000; 311 } else 312 to_msec = -1; 313 314 /* Set up the descriptors to be polled. */ 315 for (i = 0, l = protocols; l; l = l->next) { 316 struct interface_info *ip = l->local; 317 318 if (ip && (l->handler != got_one || !ip->dead)) { 319 fds[i].fd = l->fd; 320 fds[i].events = POLLIN; 321 ++i; 322 } 323 } 324 if (i == 0) 325 error("No live interfaces to poll on - exiting."); 326 327 /* Wait for a packet or a timeout... */ 328 switch (poll(fds, nfds, to_msec)) { 329 case -1: 330 if (errno != EAGAIN && errno != EINTR) 331 error("poll: %m"); 332 /* FALLTHROUGH */ 333 case 0: 334 continue; /* no packets */ 335 } 336 337 for (i = 0, l = protocols; l; l = l->next) { 338 struct interface_info *ip = l->local; 339 340 if ((fds[i].revents & (POLLIN | POLLHUP))) { 341 if (ip && (l->handler != got_one || 342 !ip->dead)) 343 (*(l->handler))(l); 344 if (interfaces_invalidated) 345 break; 346 } 347 ++i; 348 } 349 interfaces_invalidated = 0; 350 } 351} 352 353 354void 355got_one(struct protocol *l) 356{ 357 struct sockaddr_in from; 358 struct hardware hfrom; 359 struct iaddr ifrom; 360 ssize_t result; 361 union { 362 unsigned char packbuf[4095]; 363 struct dhcp_packet packet; 364 } u; 365 struct interface_info *ip = l->local; 366 367 if ((result = receive_packet(ip, u.packbuf, sizeof u, 368 &from, &hfrom)) == -1) { 369 warning("receive_packet failed on %s: %s", ip->name, 370 strerror(errno)); 371 ip->errors++; 372 if ((!interface_status(ip)) || 373 (ip->noifmedia && ip->errors > 20)) { 374 /* our interface has gone away. */ 375 warning("Interface %s no longer appears valid.", 376 ip->name); 377 ip->dead = 1; 378 interfaces_invalidated = 1; 379 close(l->fd); 380 remove_protocol(l); 381 free(ip); 382 } 383 return; 384 } 385 if (result == 0) 386 return; 387 388 if (bootp_packet_handler) { 389 ifrom.len = 4; 390 memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len); 391 392 (*bootp_packet_handler)(ip, &u.packet, result, 393 from.sin_port, ifrom, &hfrom); 394 } 395} 396 397int 398interface_status(struct interface_info *ifinfo) 399{ 400 char * ifname = ifinfo->name; 401 int ifsock = ifinfo->rfdesc; 402 struct ifreq ifr; 403 struct ifmediareq ifmr; 404 405 /* get interface flags */ 406 memset(&ifr, 0, sizeof(ifr)); 407 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 408 if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) { 409 syslog(LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m", ifname); 410 goto inactive; 411 } 412 /* 413 * if one of UP and RUNNING flags is dropped, 414 * the interface is not active. 415 */ 416 if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) 417 goto inactive; 418 419 /* Next, check carrier on the interface, if possible */ 420 if (ifinfo->noifmedia) 421 goto active; 422 memset(&ifmr, 0, sizeof(ifmr)); 423 strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name)); 424 if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) { 425 if (errno != EINVAL) { 426 syslog(LOG_DEBUG, "ioctl(SIOCGIFMEDIA) on %s: %m", 427 ifname); 428 ifinfo->noifmedia = 1; 429 goto active; 430 } 431 /* 432 * EINVAL (or ENOTTY) simply means that the interface 433 * does not support the SIOCGIFMEDIA ioctl. We regard it alive. 434 */ 435 ifinfo->noifmedia = 1; 436 goto active; 437 } 438 if (ifmr.ifm_status & IFM_AVALID) { 439 switch (ifmr.ifm_active & IFM_NMASK) { 440 case IFM_ETHER: 441 if (ifmr.ifm_status & IFM_ACTIVE) 442 goto active; 443 else 444 goto inactive; 445 break; 446 default: 447 goto inactive; 448 } 449 } 450 inactive: 451 return (0); 452 active: 453 return (1); 454} 455 456int 457locate_network(struct packet *packet) 458{ 459 struct iaddr ia; 460 461 /* If this came through a gateway, find the corresponding subnet... */ 462 if (packet->raw->giaddr.s_addr) { 463 struct subnet *subnet; 464 465 ia.len = 4; 466 memcpy(ia.iabuf, &packet->raw->giaddr, 4); 467 subnet = find_subnet(ia); 468 if (subnet) 469 packet->shared_network = subnet->shared_network; 470 else 471 packet->shared_network = NULL; 472 } else { 473 packet->shared_network = packet->interface->shared_network; 474 } 475 if (packet->shared_network) 476 return 1; 477 return 0; 478} 479 480void 481add_timeout(time_t when, void (*where)(void *), void *what) 482{ 483 struct dhcpd_timeout *t, *q; 484 485 /* See if this timeout supersedes an existing timeout. */ 486 t = NULL; 487 for (q = timeouts; q; q = q->next) { 488 if (q->func == where && q->what == what) { 489 if (t) 490 t->next = q->next; 491 else 492 timeouts = q->next; 493 break; 494 } 495 t = q; 496 } 497 498 /* If we didn't supersede a timeout, allocate a timeout 499 structure now. */ 500 if (!q) { 501 if (free_timeouts) { 502 q = free_timeouts; 503 free_timeouts = q->next; 504 q->func = where; 505 q->what = what; 506 } else { 507 q = (struct dhcpd_timeout *)malloc(sizeof (struct dhcpd_timeout)); 508 if (!q) 509 error("Can't allocate timeout structure!"); 510 q->func = where; 511 q->what = what; 512 } 513 } 514 515 q->when = when; 516 517 /* Now sort this timeout into the timeout list. */ 518 519 /* Beginning of list? */ 520 if (!timeouts || timeouts->when > q->when) { 521 q->next = timeouts; 522 timeouts = q; 523 return; 524 } 525 526 /* Middle of list? */ 527 for (t = timeouts; t->next; t = t->next) { 528 if (t->next->when > q->when) { 529 q->next = t->next; 530 t->next = q; 531 return; 532 } 533 } 534 535 /* End of list. */ 536 t->next = q; 537 q->next = NULL; 538} 539 540void 541cancel_timeout(void (*where)(void *), void *what) 542{ 543 struct dhcpd_timeout *t, *q; 544 545 /* Look for this timeout on the list, and unlink it if we find it. */ 546 t = NULL; 547 for (q = timeouts; q; q = q->next) { 548 if (q->func == where && q->what == what) { 549 if (t) 550 t->next = q->next; 551 else 552 timeouts = q->next; 553 break; 554 } 555 t = q; 556 } 557 558 /* If we found the timeout, put it on the free list. */ 559 if (q) { 560 q->next = free_timeouts; 561 free_timeouts = q; 562 } 563} 564 565/* Add a protocol to the list of protocols... */ 566void 567add_protocol(char *name, int fd, void (*handler)(struct protocol *), 568 void *local) 569{ 570 struct protocol *p; 571 572 p = (struct protocol *)malloc(sizeof *p); 573 if (!p) 574 error("can't allocate protocol struct for %s", name); 575 p->fd = fd; 576 p->handler = handler; 577 p->local = local; 578 p->next = protocols; 579 protocols = p; 580} 581 582void 583remove_protocol(struct protocol *proto) 584{ 585 struct protocol *p, *next, *prev = NULL; 586 587 for (p = protocols; p; p = next) { 588 next = p->next; 589 if (p == proto) { 590 if (prev) 591 prev->next = p->next; 592 else 593 protocols = p->next; 594 free(p); 595 } 596 } 597} 598