1 /* $OpenBSD: dispatch.c,v 1.23 2021/01/17 13:40:59 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 struct dhcp_packet *, int, struct packet_ctx *); 83 84 static int interface_status(struct interface_info *ifinfo); 85 86 struct interface_info * 87 iflist_getbyname(const char *name) 88 { 89 struct interface_info *intf; 90 91 TAILQ_FOREACH(intf, &intflist, entry) { 92 if (strcmp(intf->name, name) != 0) 93 continue; 94 95 return intf; 96 } 97 98 return NULL; 99 } 100 101 void 102 setup_iflist(void) 103 { 104 struct interface_info *intf; 105 struct sockaddr_dl *sdl; 106 struct ifaddrs *ifap, *ifa; 107 struct if_data *ifi; 108 struct sockaddr_in *sin; 109 struct sockaddr_in6 *sin6; 110 111 TAILQ_INIT(&intflist); 112 if (getifaddrs(&ifap)) 113 fatalx("getifaddrs failed"); 114 115 for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) { 116 if ((ifa->ifa_flags & IFF_LOOPBACK) || 117 (ifa->ifa_flags & IFF_POINTOPOINT)) 118 continue; 119 120 /* Find interface or create it. */ 121 intf = iflist_getbyname(ifa->ifa_name); 122 if (intf == NULL) { 123 intf = calloc(1, sizeof(*intf)); 124 if (intf == NULL) 125 fatal("calloc"); 126 127 strlcpy(intf->name, ifa->ifa_name, 128 sizeof(intf->name)); 129 TAILQ_INSERT_HEAD(&intflist, intf, entry); 130 } 131 132 /* Signal disabled interface. */ 133 if ((ifa->ifa_flags & IFF_UP) == 0) 134 intf->dead = 1; 135 136 if (ifa->ifa_addr->sa_family == AF_LINK) { 137 sdl = (struct sockaddr_dl *)ifa->ifa_addr; 138 ifi = (struct if_data *)ifa->ifa_data; 139 140 /* Skip unsupported interfaces. */ 141 if (ifi->ifi_type != IFT_ETHER && 142 ifi->ifi_type != IFT_ENC && 143 ifi->ifi_type != IFT_CARP) { 144 TAILQ_REMOVE(&intflist, intf, entry); 145 free(intf); 146 continue; 147 } 148 149 if (ifi->ifi_type == IFT_ENC) 150 intf->hw_address.htype = HTYPE_IPSEC_TUNNEL; 151 else 152 intf->hw_address.htype = HTYPE_ETHER; 153 154 intf->index = sdl->sdl_index; 155 intf->hw_address.hlen = sdl->sdl_alen; 156 memcpy(intf->hw_address.haddr, 157 LLADDR(sdl), sdl->sdl_alen); 158 } else if (ifa->ifa_addr->sa_family == AF_INET) { 159 sin = (struct sockaddr_in *)ifa->ifa_addr; 160 if (sin->sin_addr.s_addr == htonl(INADDR_LOOPBACK) || 161 intf->primary_address.s_addr != INADDR_ANY) 162 continue; 163 164 intf->primary_address = sin->sin_addr; 165 } else if (ifa->ifa_addr->sa_family == AF_INET6) { 166 sin6 = (struct sockaddr_in6 *)ifa->ifa_addr; 167 if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) { 168 intf->linklocal = sin6->sin6_addr; 169 #ifdef __KAME__ 170 /* 171 * Remove possible scope from address if 172 * link-local. 173 */ 174 intf->linklocal.s6_addr[2] = 0; 175 intf->linklocal.s6_addr[3] = 0; 176 #endif 177 } else 178 intf->gipv6 = 1; 179 180 /* At least one IPv6 address was found. */ 181 intf->ipv6 = 1; 182 } 183 } 184 185 freeifaddrs(ifap); 186 187 /* 188 * Generate link-local IPv6 address for interfaces without it. 189 * 190 * For IPv6 DHCP Relay it doesn't matter what is used for 191 * link-addr field, so let's generate an address that won't 192 * change during execution so we can always find the interface 193 * to relay packets back. This is only used for layer 2 relaying 194 * when the interface might not have an address. 195 */ 196 TAILQ_FOREACH(intf, &intflist, entry) { 197 if (memcmp(&intf->linklocal, &in6addr_any, 198 sizeof(in6addr_any)) != 0) 199 continue; 200 201 intf->linklocal.s6_addr[0] = 0xfe; 202 intf->linklocal.s6_addr[1] = 0x80; 203 intf->linklocal.s6_addr[8] = intf->hw_address.haddr[0]; 204 intf->linklocal.s6_addr[9] = intf->hw_address.haddr[1]; 205 intf->linklocal.s6_addr[10] = intf->hw_address.haddr[2]; 206 intf->linklocal.s6_addr[11] = 0xff; 207 intf->linklocal.s6_addr[12] = 0xfe; 208 intf->linklocal.s6_addr[13] = intf->hw_address.haddr[3]; 209 intf->linklocal.s6_addr[14] = intf->hw_address.haddr[4]; 210 intf->linklocal.s6_addr[15] = intf->hw_address.haddr[5]; 211 EUI64_TO_IFID(&intf->linklocal); 212 } 213 } 214 215 struct interface_info * 216 register_interface(const char *ifname, void (*handler)(struct protocol *), 217 int isserver) 218 { 219 struct interface_info *intf; 220 221 if ((intf = iflist_getbyname(ifname)) == NULL) 222 return NULL; 223 224 /* Don't register disabled interfaces. */ 225 if (intf->dead) 226 return NULL; 227 228 /* Check if we already registered the interface. */ 229 if (intf->ifr.ifr_name[0] != 0) 230 return intf; 231 232 if (strlcpy(intf->ifr.ifr_name, ifname, 233 sizeof(intf->ifr.ifr_name)) >= sizeof(intf->ifr.ifr_name)) 234 fatalx("interface name '%s' too long", ifname); 235 236 if_register_receive(intf, isserver); 237 if_register_send(intf); 238 add_protocol(intf->name, intf->rfdesc, handler, intf); 239 240 return intf; 241 } 242 243 /* 244 * Wait for packets to come in using poll(). When a packet comes in, 245 * call receive_packet to receive the packet and possibly strip hardware 246 * addressing information from it, and then call through the 247 * bootp_packet_handler hook to try to do something with it. 248 */ 249 void 250 dispatch(void) 251 { 252 int count, i, to_msec, nfds = 0; 253 struct protocol *l; 254 struct pollfd *fds; 255 time_t howlong; 256 257 nfds = 0; 258 for (l = protocols; l; l = l->next) 259 nfds++; 260 261 fds = calloc(nfds, sizeof(struct pollfd)); 262 if (fds == NULL) 263 fatalx("Can't allocate poll structures."); 264 265 do { 266 /* 267 * Call any expired timeouts, and then if there's still 268 * a timeout registered, time out the select call then. 269 */ 270 another: 271 if (timeouts) { 272 if (timeouts->when <= cur_time) { 273 struct timeout *t = timeouts; 274 275 timeouts = timeouts->next; 276 (*(t->func))(t->what); 277 t->next = free_timeouts; 278 free_timeouts = t; 279 goto another; 280 } 281 282 /* 283 * Figure timeout in milliseconds, and check for 284 * potential overflow, so we can cram into an 285 * int for poll, while not polling with a 286 * negative timeout and blocking indefinitely. 287 */ 288 howlong = timeouts->when - cur_time; 289 if (howlong > INT_MAX / 1000) 290 howlong = INT_MAX / 1000; 291 to_msec = howlong * 1000; 292 } else 293 to_msec = -1; 294 295 /* Set up the descriptors to be polled. */ 296 i = 0; 297 298 for (l = protocols; l; l = l->next) { 299 struct interface_info *ip = l->local; 300 301 if (ip && (l->handler != got_one || !ip->dead)) { 302 fds[i].fd = l->fd; 303 fds[i].events = POLLIN; 304 fds[i].revents = 0; 305 i++; 306 } 307 } 308 309 if (i == 0) 310 fatalx("No live interfaces to poll on - exiting."); 311 312 /* Wait for a packet or a timeout... XXX */ 313 count = poll(fds, nfds, to_msec); 314 315 /* Not likely to be transitory... */ 316 if (count == -1) { 317 if (errno == EAGAIN || errno == EINTR) { 318 time(&cur_time); 319 continue; 320 } 321 else 322 fatal("poll"); 323 } 324 325 /* Get the current time... */ 326 time(&cur_time); 327 328 i = 0; 329 for (l = protocols; l; l = l->next) { 330 struct interface_info *ip = l->local; 331 332 if ((fds[i].revents & (POLLIN | POLLHUP))) { 333 fds[i].revents = 0; 334 if (ip && (l->handler != got_one || 335 !ip->dead)) 336 (*(l->handler))(l); 337 if (interfaces_invalidated) 338 break; 339 } 340 i++; 341 } 342 interfaces_invalidated = 0; 343 } while (1); 344 } 345 346 347 void 348 got_one(struct protocol *l) 349 { 350 struct packet_ctx pc; 351 ssize_t result; 352 union { 353 /* 354 * Packet input buffer. Must be as large as largest 355 * possible MTU. 356 */ 357 unsigned char packbuf[4095]; 358 struct dhcp_packet packet; 359 } u; 360 struct interface_info *ip = l->local; 361 362 memset(&pc, 0, sizeof(pc)); 363 364 if ((result = receive_packet(ip, u.packbuf, sizeof(u), &pc)) == -1) { 365 log_warn("receive_packet failed on %s", ip->name); 366 ip->errors++; 367 if ((!interface_status(ip)) || 368 (ip->noifmedia && ip->errors > 20)) { 369 /* our interface has gone away. */ 370 log_warnx("Interface %s no longer appears valid.", 371 ip->name); 372 ip->dead = 1; 373 interfaces_invalidated = 1; 374 close(l->fd); 375 remove_protocol(l); 376 free(ip); 377 } 378 return; 379 } 380 if (result == 0) 381 return; 382 383 if (bootp_packet_handler) 384 (*bootp_packet_handler)(ip, &u.packet, result, &pc); 385 } 386 387 int 388 interface_status(struct interface_info *ifinfo) 389 { 390 char *ifname = ifinfo->name; 391 int ifsock = ifinfo->rfdesc; 392 struct ifreq ifr; 393 struct ifmediareq ifmr; 394 395 /* get interface flags */ 396 memset(&ifr, 0, sizeof(ifr)); 397 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 398 if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) == -1) { 399 log_warn("ioctl(SIOCGIFFLAGS) on %s", ifname); 400 goto inactive; 401 } 402 /* 403 * if one of UP and RUNNING flags is dropped, 404 * the interface is not active. 405 */ 406 if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) { 407 goto inactive; 408 } 409 /* Next, check carrier on the interface, if possible */ 410 if (ifinfo->noifmedia) 411 goto active; 412 memset(&ifmr, 0, sizeof(ifmr)); 413 strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name)); 414 if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) { 415 if (errno != EINVAL) { 416 log_debug("ioctl(SIOCGIFMEDIA) on %s", ifname); 417 ifinfo->noifmedia = 1; 418 goto active; 419 } 420 /* 421 * EINVAL (or ENOTTY) simply means that the interface 422 * does not support the SIOCGIFMEDIA ioctl. We regard it alive. 423 */ 424 ifinfo->noifmedia = 1; 425 goto active; 426 } 427 if (ifmr.ifm_status & IFM_AVALID) { 428 switch (ifmr.ifm_active & IFM_NMASK) { 429 case IFM_ETHER: 430 if (ifmr.ifm_status & IFM_ACTIVE) 431 goto active; 432 else 433 goto inactive; 434 break; 435 default: 436 goto inactive; 437 } 438 } 439 inactive: 440 return (0); 441 active: 442 return (1); 443 } 444 445 /* Add a protocol to the list of protocols... */ 446 void 447 add_protocol(char *name, int fd, void (*handler)(struct protocol *), 448 void *local) 449 { 450 struct protocol *p; 451 452 p = malloc(sizeof(*p)); 453 if (!p) 454 fatalx("can't allocate protocol struct for %s", name); 455 456 p->fd = fd; 457 p->handler = handler; 458 p->local = local; 459 p->next = protocols; 460 protocols = p; 461 } 462 463 void 464 remove_protocol(struct protocol *proto) 465 { 466 struct protocol *p, *next, *prev; 467 468 prev = NULL; 469 for (p = protocols; p; p = next) { 470 next = p->next; 471 if (p == proto) { 472 if (prev) 473 prev->next = p->next; 474 else 475 protocols = p->next; 476 free(p); 477 } 478 } 479 } 480