1 /* $OpenBSD: dispatch.c,v 1.2 2021/01/17 13:41:24 claudio Exp $ */ 2 3 /* 4 * Copyright 2004 Henning Brauer <henning@openbsd.org> 5 * Copyright (c) 1995, 1996, 1997, 1998, 1999 6 * The Internet Software Consortium. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of The Internet Software Consortium nor the names 18 * of its contributors may be used to endorse or promote products derived 19 * from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND 22 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 23 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 24 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 25 * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR 26 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 27 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 28 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 29 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 30 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 31 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 32 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * This software has been written for the Internet Software Consortium 36 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie 37 * Enterprises. To learn more about the Internet Software Consortium, 38 * see ``http://www.vix.com/isc''. To learn more about Vixie 39 * Enterprises, see ``http://www.vix.com''. 40 */ 41 42 #include <sys/types.h> 43 #include <sys/ioctl.h> 44 #include <sys/socket.h> 45 46 #include <net/if.h> 47 #include <net/if_dl.h> 48 #include <net/if_media.h> 49 #include <net/if_types.h> 50 51 #include <netinet/in.h> 52 #include <netinet/if_ether.h> 53 54 #include <errno.h> 55 #include <ifaddrs.h> 56 #include <limits.h> 57 #include <poll.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 "dhcpd.h" 66 #include "log.h" 67 68 /* 69 * Macros implementation used to generate link-local addresses. This 70 * code was copied from: sys/netinet6/in6_ifattach.c. 71 */ 72 #define EUI64_UBIT 0x02 73 #define EUI64_TO_IFID(in6) \ 74 do { (in6)->s6_addr[8] ^= EUI64_UBIT; } while (0) 75 76 struct protocol *protocols; 77 struct timeout *timeouts; 78 static struct timeout *free_timeouts; 79 static int interfaces_invalidated; 80 81 void (*bootp_packet_handler)(struct interface_info *, 82 void *, size_t, struct packet_ctx *); 83 84 static int interface_status(struct interface_info *ifinfo); 85 86 struct interface_info * 87 iflist_getbyindex(unsigned int index) 88 { 89 struct interface_info *intf; 90 91 TAILQ_FOREACH(intf, &intflist, entry) { 92 if (intf->index != index) 93 continue; 94 95 return intf; 96 } 97 98 return NULL; 99 } 100 101 struct interface_info * 102 iflist_getbyname(const char *name) 103 { 104 struct interface_info *intf; 105 106 TAILQ_FOREACH(intf, &intflist, entry) { 107 if (strcmp(intf->name, name) != 0) 108 continue; 109 110 return intf; 111 } 112 113 return NULL; 114 } 115 116 struct interface_info * 117 iflist_getbyaddr6(struct in6_addr *addr) 118 { 119 struct interface_info *intf; 120 121 TAILQ_FOREACH(intf, &intflist, entry) { 122 /* Look for link-layer address. */ 123 if (memcmp(&intf->linklocal, addr, sizeof(*addr)) == 0) 124 return intf; 125 } 126 127 return NULL; 128 } 129 130 void 131 setup_iflist(void) 132 { 133 struct interface_info *intf; 134 struct sockaddr_dl *sdl; 135 struct ifaddrs *ifap, *ifa; 136 struct if_data *ifi; 137 struct sockaddr_in *sin; 138 struct sockaddr_in6 *sin6; 139 140 TAILQ_INIT(&intflist); 141 if (getifaddrs(&ifap)) 142 fatalx("getifaddrs failed"); 143 144 for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) { 145 if ((ifa->ifa_flags & IFF_LOOPBACK) || 146 (ifa->ifa_flags & IFF_POINTOPOINT)) 147 continue; 148 149 /* Find interface or create it. */ 150 intf = iflist_getbyname(ifa->ifa_name); 151 if (intf == NULL) { 152 intf = calloc(1, sizeof(*intf)); 153 if (intf == NULL) 154 fatal("calloc"); 155 156 strlcpy(intf->name, ifa->ifa_name, 157 sizeof(intf->name)); 158 TAILQ_INSERT_HEAD(&intflist, intf, entry); 159 } 160 161 /* Signal disabled interface. */ 162 if ((ifa->ifa_flags & IFF_UP) == 0) 163 intf->dead = 1; 164 165 if (ifa->ifa_addr->sa_family == AF_LINK) { 166 sdl = (struct sockaddr_dl *)ifa->ifa_addr; 167 ifi = (struct if_data *)ifa->ifa_data; 168 169 /* Skip non ethernet interfaces. */ 170 if (ifi->ifi_type != IFT_ETHER && 171 ifi->ifi_type != IFT_ENC) { 172 TAILQ_REMOVE(&intflist, intf, entry); 173 free(intf); 174 continue; 175 } 176 177 intf->index = sdl->sdl_index; 178 intf->hw_address.hlen = sdl->sdl_alen; 179 memcpy(intf->hw_address.haddr, 180 LLADDR(sdl), sdl->sdl_alen); 181 } else if (ifa->ifa_addr->sa_family == AF_INET) { 182 sin = (struct sockaddr_in *)ifa->ifa_addr; 183 if (sin->sin_addr.s_addr == htonl(INADDR_LOOPBACK) || 184 intf->primary_address.s_addr != INADDR_ANY) 185 continue; 186 187 intf->primary_address = sin->sin_addr; 188 } else if (ifa->ifa_addr->sa_family == AF_INET6) { 189 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr; 190 if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) { 191 intf->linklocal = sin6->sin6_addr; 192 #ifdef __KAME__ 193 /* 194 * Remove possible scope from address if 195 * link-local. 196 */ 197 intf->linklocal.s6_addr[2] = 0; 198 intf->linklocal.s6_addr[3] = 0; 199 #endif 200 } else 201 intf->gipv6 = 1; 202 203 /* At least one IPv6 address was found. */ 204 intf->ipv6 = 1; 205 } 206 } 207 208 freeifaddrs(ifap); 209 210 /* 211 * Generate link-local IPv6 address for interfaces without it. 212 * 213 * For IPv6 DHCP Relay it doesn't matter what is used for 214 * link-addr field, so let's generate an address that won't 215 * change during execution so we can always find the interface 216 * to relay packets back. This is only used for layer 2 relaying 217 * when the interface might not have an address. 218 */ 219 TAILQ_FOREACH(intf, &intflist, entry) { 220 if (memcmp(&intf->linklocal, &in6addr_any, 221 sizeof(in6addr_any)) != 0) 222 continue; 223 224 intf->linklocal.s6_addr[0] = 0xfe; 225 intf->linklocal.s6_addr[1] = 0x80; 226 intf->linklocal.s6_addr[8] = intf->hw_address.haddr[0]; 227 intf->linklocal.s6_addr[9] = intf->hw_address.haddr[1]; 228 intf->linklocal.s6_addr[10] = intf->hw_address.haddr[2]; 229 intf->linklocal.s6_addr[11] = 0xff; 230 intf->linklocal.s6_addr[12] = 0xfe; 231 intf->linklocal.s6_addr[13] = intf->hw_address.haddr[3]; 232 intf->linklocal.s6_addr[14] = intf->hw_address.haddr[4]; 233 intf->linklocal.s6_addr[15] = intf->hw_address.haddr[5]; 234 EUI64_TO_IFID(&intf->linklocal); 235 } 236 } 237 238 struct interface_info * 239 register_interface(const char *ifname, void (*handler)(struct protocol *)) 240 { 241 struct interface_info *intf; 242 243 if ((intf = iflist_getbyname(ifname)) == NULL) 244 return NULL; 245 246 /* Don't register disabled interfaces. */ 247 if (intf->dead) 248 return NULL; 249 250 /* Check if we already registered the interface. */ 251 if (intf->ifr.ifr_name[0] != 0) 252 return intf; 253 254 if (strlcpy(intf->ifr.ifr_name, ifname, 255 sizeof(intf->ifr.ifr_name)) >= sizeof(intf->ifr.ifr_name)) 256 fatalx("interface name '%s' too long", ifname); 257 258 if_register_receive(intf); 259 if_register_send(intf); 260 add_protocol(intf->name, intf->rfdesc, handler, intf); 261 262 return intf; 263 } 264 265 /* 266 * Wait for packets to come in using poll(). When a packet comes in, 267 * call receive_packet to receive the packet and possibly strip hardware 268 * addressing information from it, and then call through the 269 * bootp_packet_handler hook to try to do something with it. 270 */ 271 void 272 dispatch(void) 273 { 274 int count, i, to_msec, nfds = 0; 275 struct protocol *l; 276 struct pollfd *fds; 277 time_t howlong; 278 279 nfds = 0; 280 for (l = protocols; l; l = l->next) 281 nfds++; 282 283 fds = calloc(nfds, sizeof(struct pollfd)); 284 if (fds == NULL) 285 fatalx("Can't allocate poll structures."); 286 287 do { 288 /* 289 * Call any expired timeouts, and then if there's still 290 * a timeout registered, time out the select call then. 291 */ 292 another: 293 if (timeouts) { 294 if (timeouts->when <= cur_time) { 295 struct timeout *t = timeouts; 296 297 timeouts = timeouts->next; 298 (*(t->func))(t->what); 299 t->next = free_timeouts; 300 free_timeouts = t; 301 goto another; 302 } 303 304 /* 305 * Figure timeout in milliseconds, and check for 306 * potential overflow, so we can cram into an 307 * int for poll, while not polling with a 308 * negative timeout and blocking indefinitely. 309 */ 310 howlong = timeouts->when - cur_time; 311 if (howlong > INT_MAX / 1000) 312 howlong = INT_MAX / 1000; 313 to_msec = howlong * 1000; 314 } else 315 to_msec = -1; 316 317 /* Set up the descriptors to be polled. */ 318 i = 0; 319 320 for (l = protocols; l; l = l->next) { 321 struct interface_info *ip = l->local; 322 323 if (ip && (l->handler != got_one || !ip->dead)) { 324 fds[i].fd = l->fd; 325 fds[i].events = POLLIN; 326 fds[i].revents = 0; 327 i++; 328 } 329 } 330 331 if (i == 0) 332 fatalx("No live interfaces to poll on - exiting."); 333 334 /* Wait for a packet or a timeout... XXX */ 335 count = poll(fds, nfds, to_msec); 336 337 /* Not likely to be transitory... */ 338 if (count == -1) { 339 if (errno == EAGAIN || errno == EINTR) { 340 time(&cur_time); 341 continue; 342 } 343 else 344 fatal("poll"); 345 } 346 347 /* Get the current time... */ 348 time(&cur_time); 349 350 i = 0; 351 for (l = protocols; l; l = l->next) { 352 struct interface_info *ip = l->local; 353 354 if ((fds[i].revents & (POLLIN | POLLHUP))) { 355 fds[i].revents = 0; 356 if (ip && (l->handler != got_one || 357 !ip->dead)) 358 (*(l->handler))(l); 359 if (interfaces_invalidated) 360 break; 361 } 362 i++; 363 } 364 interfaces_invalidated = 0; 365 } while (1); 366 } 367 368 369 void 370 got_one(struct protocol *l) 371 { 372 struct packet_ctx pc; 373 ssize_t result; 374 uint8_t buf[4096]; 375 struct interface_info *ip = l->local; 376 377 memset(&pc, 0, sizeof(pc)); 378 379 if ((result = receive_packet(ip, buf, sizeof(buf), &pc)) == -1) { 380 log_warn("receive_packet failed on %s", ip->name); 381 ip->errors++; 382 if ((!interface_status(ip)) || 383 (ip->noifmedia && ip->errors > 20)) { 384 /* our interface has gone away. */ 385 log_warnx("Interface %s no longer appears valid.", 386 ip->name); 387 ip->dead = 1; 388 interfaces_invalidated = 1; 389 close(l->fd); 390 remove_protocol(l); 391 free(ip); 392 } 393 return; 394 } 395 if (result == 0) 396 return; 397 398 if (bootp_packet_handler) 399 (*bootp_packet_handler)(ip, buf, result, &pc); 400 } 401 402 int 403 interface_status(struct interface_info *ifinfo) 404 { 405 char *ifname = ifinfo->name; 406 int ifsock = ifinfo->rfdesc; 407 struct ifreq ifr; 408 struct ifmediareq ifmr; 409 410 /* get interface flags */ 411 memset(&ifr, 0, sizeof(ifr)); 412 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 413 if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) == -1) { 414 log_warn("ioctl(SIOCGIFFLAGS) on %s", ifname); 415 goto inactive; 416 } 417 /* 418 * if one of UP and RUNNING flags is dropped, 419 * the interface is not active. 420 */ 421 if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) { 422 goto inactive; 423 } 424 /* Next, check carrier on the interface, if possible */ 425 if (ifinfo->noifmedia) 426 goto active; 427 memset(&ifmr, 0, sizeof(ifmr)); 428 strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name)); 429 if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) { 430 if (errno != EINVAL) { 431 log_debug("ioctl(SIOCGIFMEDIA) on %s", ifname); 432 ifinfo->noifmedia = 1; 433 goto active; 434 } 435 /* 436 * EINVAL (or ENOTTY) simply means that the interface 437 * does not support the SIOCGIFMEDIA ioctl. We regard it alive. 438 */ 439 ifinfo->noifmedia = 1; 440 goto active; 441 } 442 if (ifmr.ifm_status & IFM_AVALID) { 443 switch (ifmr.ifm_active & IFM_NMASK) { 444 case IFM_ETHER: 445 if (ifmr.ifm_status & IFM_ACTIVE) 446 goto active; 447 else 448 goto inactive; 449 break; 450 default: 451 goto inactive; 452 } 453 } 454 inactive: 455 return (0); 456 active: 457 return (1); 458 } 459 460 /* Add a protocol to the list of protocols... */ 461 void 462 add_protocol(char *name, int fd, void (*handler)(struct protocol *), 463 void *local) 464 { 465 struct protocol *p; 466 467 p = malloc(sizeof(*p)); 468 if (!p) 469 fatalx("can't allocate protocol struct for %s", name); 470 471 p->fd = fd; 472 p->handler = handler; 473 p->local = local; 474 p->next = protocols; 475 protocols = p; 476 } 477 478 void 479 remove_protocol(struct protocol *proto) 480 { 481 struct protocol *p, *next, *prev; 482 483 prev = NULL; 484 for (p = protocols; p; p = next) { 485 next = p->next; 486 if (p == proto) { 487 if (prev) 488 prev->next = p->next; 489 else 490 protocols = p->next; 491 free(p); 492 } 493 } 494 } 495