1 /* $OpenBSD: dispatch.c,v 1.10 2016/02/07 00:49:28 krw 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 53 #include <errno.h> 54 #include <ifaddrs.h> 55 #include <limits.h> 56 #include <poll.h> 57 #include <stdlib.h> 58 #include <string.h> 59 #include <syslog.h> 60 #include <unistd.h> 61 62 #include "dhcp.h" 63 #include "dhcpd.h" 64 65 struct protocol *protocols; 66 struct timeout *timeouts; 67 static struct timeout *free_timeouts; 68 static int interfaces_invalidated; 69 70 void (*bootp_packet_handler)(struct interface_info *, 71 struct dhcp_packet *, int, unsigned int, 72 struct iaddr, struct hardware *); 73 74 static int interface_status(struct interface_info *ifinfo); 75 76 /* 77 * Use getifaddrs() to get a list of all the attached interfaces. For 78 * each interface that's of type INET and not the loopback interface, 79 * register that interface with the network I/O software, figure out 80 * what subnet it's on, and add it to the list of interfaces. 81 */ 82 void 83 discover_interfaces(struct interface_info *iface) 84 { 85 struct sockaddr_in foo; 86 struct ifaddrs *ifap, *ifa; 87 struct ifreq *tif; 88 89 if (getifaddrs(&ifap) != 0) 90 error("getifaddrs failed"); 91 92 for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) { 93 if ((ifa->ifa_flags & IFF_LOOPBACK) || 94 (ifa->ifa_flags & IFF_POINTOPOINT) || 95 (!(ifa->ifa_flags & IFF_UP))) 96 continue; 97 98 if (strcmp(iface->name, ifa->ifa_name)) 99 continue; 100 101 /* 102 * If we have the capability, extract link information 103 * and record it in a linked list. 104 */ 105 if (ifa->ifa_addr->sa_family == AF_LINK) { 106 struct sockaddr_dl *foo = 107 (struct sockaddr_dl *)ifa->ifa_addr; 108 struct if_data *ifi = 109 (struct if_data *)ifa->ifa_data; 110 111 iface->index = foo->sdl_index; 112 iface->hw_address.hlen = foo->sdl_alen; 113 if (ifi->ifi_type == IFT_ENC) 114 iface->hw_address.htype = HTYPE_IPSEC_TUNNEL; 115 else 116 iface->hw_address.htype = HTYPE_ETHER; /* XXX */ 117 memcpy(iface->hw_address.haddr, 118 LLADDR(foo), foo->sdl_alen); 119 } else if (ifa->ifa_addr->sa_family == AF_INET) { 120 struct iaddr addr; 121 122 memcpy(&foo, ifa->ifa_addr, sizeof(foo)); 123 if (foo.sin_addr.s_addr == htonl(INADDR_LOOPBACK)) 124 continue; 125 if (!iface->ifp) { 126 int len = IFNAMSIZ + ifa->ifa_addr->sa_len; 127 128 if ((tif = malloc(len)) == NULL) 129 error("no space to remember ifp"); 130 strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ); 131 memcpy(&tif->ifr_addr, ifa->ifa_addr, 132 ifa->ifa_addr->sa_len); 133 iface->ifp = tif; 134 iface->primary_address = foo.sin_addr; 135 } 136 addr.len = 4; 137 memcpy(addr.iabuf, &foo.sin_addr.s_addr, addr.len); 138 } 139 } 140 141 if (!iface->ifp) 142 error("%s: not found", iface->name); 143 144 /* Register the interface... */ 145 if_register_receive(iface); 146 if_register_send(iface); 147 add_protocol(iface->name, iface->rfdesc, got_one, iface); 148 freeifaddrs(ifap); 149 } 150 151 /* 152 * Wait for packets to come in using poll(). When a packet comes in, 153 * call receive_packet to receive the packet and possibly strip hardware 154 * addressing information from it, and then call through the 155 * bootp_packet_handler hook to try to do something with it. 156 */ 157 void 158 dispatch(void) 159 { 160 int count, i, to_msec, nfds = 0; 161 struct protocol *l; 162 struct pollfd *fds; 163 time_t howlong; 164 165 nfds = 0; 166 for (l = protocols; l; l = l->next) 167 nfds++; 168 169 fds = calloc(nfds, sizeof(struct pollfd)); 170 if (fds == NULL) 171 error("Can't allocate poll structures."); 172 173 do { 174 /* 175 * Call any expired timeouts, and then if there's still 176 * a timeout registered, time out the select call then. 177 */ 178 another: 179 if (timeouts) { 180 if (timeouts->when <= cur_time) { 181 struct timeout *t = timeouts; 182 183 timeouts = timeouts->next; 184 (*(t->func))(t->what); 185 t->next = free_timeouts; 186 free_timeouts = t; 187 goto another; 188 } 189 190 /* 191 * Figure timeout in milliseconds, and check for 192 * potential overflow, so we can cram into an 193 * int for poll, while not polling with a 194 * negative timeout and blocking indefinitely. 195 */ 196 howlong = timeouts->when - cur_time; 197 if (howlong > INT_MAX / 1000) 198 howlong = INT_MAX / 1000; 199 to_msec = howlong * 1000; 200 } else 201 to_msec = -1; 202 203 /* Set up the descriptors to be polled. */ 204 i = 0; 205 206 for (l = protocols; l; l = l->next) { 207 struct interface_info *ip = l->local; 208 209 if (ip && (l->handler != got_one || !ip->dead)) { 210 fds[i].fd = l->fd; 211 fds[i].events = POLLIN; 212 fds[i].revents = 0; 213 i++; 214 } 215 } 216 217 if (i == 0) 218 error("No live interfaces to poll on - exiting."); 219 220 /* Wait for a packet or a timeout... XXX */ 221 count = poll(fds, nfds, to_msec); 222 223 /* Not likely to be transitory... */ 224 if (count == -1) { 225 if (errno == EAGAIN || errno == EINTR) { 226 time(&cur_time); 227 continue; 228 } 229 else 230 error("poll: %m"); 231 } 232 233 /* Get the current time... */ 234 time(&cur_time); 235 236 i = 0; 237 for (l = protocols; l; l = l->next) { 238 struct interface_info *ip = l->local; 239 240 if ((fds[i].revents & (POLLIN | POLLHUP))) { 241 fds[i].revents = 0; 242 if (ip && (l->handler != got_one || 243 !ip->dead)) 244 (*(l->handler))(l); 245 if (interfaces_invalidated) 246 break; 247 } 248 i++; 249 } 250 interfaces_invalidated = 0; 251 } while (1); 252 } 253 254 255 void 256 got_one(struct protocol *l) 257 { 258 struct sockaddr_in from; 259 struct hardware hfrom; 260 struct iaddr ifrom; 261 size_t result; 262 union { 263 /* 264 * Packet input buffer. Must be as large as largest 265 * possible MTU. 266 */ 267 unsigned char packbuf[4095]; 268 struct dhcp_packet packet; 269 } u; 270 struct interface_info *ip = l->local; 271 272 if ((result = receive_packet(ip, u.packbuf, sizeof(u), &from, 273 &hfrom)) == -1) { 274 warning("receive_packet failed on %s: %s", ip->name, 275 strerror(errno)); 276 ip->errors++; 277 if ((!interface_status(ip)) || 278 (ip->noifmedia && ip->errors > 20)) { 279 /* our interface has gone away. */ 280 warning("Interface %s no longer appears valid.", 281 ip->name); 282 ip->dead = 1; 283 interfaces_invalidated = 1; 284 close(l->fd); 285 remove_protocol(l); 286 free(ip); 287 } 288 return; 289 } 290 if (result == 0) 291 return; 292 293 if (bootp_packet_handler) { 294 ifrom.len = 4; 295 memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len); 296 297 (*bootp_packet_handler)(ip, &u.packet, result, 298 from.sin_port, ifrom, &hfrom); 299 } 300 } 301 302 int 303 interface_status(struct interface_info *ifinfo) 304 { 305 char *ifname = ifinfo->name; 306 int ifsock = ifinfo->rfdesc; 307 struct ifreq ifr; 308 struct ifmediareq ifmr; 309 310 /* get interface flags */ 311 memset(&ifr, 0, sizeof(ifr)); 312 strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 313 if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) == -1) { 314 syslog(LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m", ifname); 315 goto inactive; 316 } 317 /* 318 * if one of UP and RUNNING flags is dropped, 319 * the interface is not active. 320 */ 321 if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) { 322 goto inactive; 323 } 324 /* Next, check carrier on the interface, if possible */ 325 if (ifinfo->noifmedia) 326 goto active; 327 memset(&ifmr, 0, sizeof(ifmr)); 328 strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name)); 329 if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) { 330 if (errno != EINVAL) { 331 syslog(LOG_DEBUG, "ioctl(SIOCGIFMEDIA) on %s: %m", 332 ifname); 333 334 ifinfo->noifmedia = 1; 335 goto active; 336 } 337 /* 338 * EINVAL (or ENOTTY) simply means that the interface 339 * does not support the SIOCGIFMEDIA ioctl. We regard it alive. 340 */ 341 ifinfo->noifmedia = 1; 342 goto active; 343 } 344 if (ifmr.ifm_status & IFM_AVALID) { 345 switch (ifmr.ifm_active & IFM_NMASK) { 346 case IFM_ETHER: 347 if (ifmr.ifm_status & IFM_ACTIVE) 348 goto active; 349 else 350 goto inactive; 351 break; 352 default: 353 goto inactive; 354 } 355 } 356 inactive: 357 return (0); 358 active: 359 return (1); 360 } 361 362 /* Add a protocol to the list of protocols... */ 363 void 364 add_protocol(char *name, int fd, void (*handler)(struct protocol *), 365 void *local) 366 { 367 struct protocol *p; 368 369 p = malloc(sizeof(*p)); 370 if (!p) 371 error("can't allocate protocol struct for %s", name); 372 373 p->fd = fd; 374 p->handler = handler; 375 p->local = local; 376 p->next = protocols; 377 protocols = p; 378 } 379 380 void 381 remove_protocol(struct protocol *proto) 382 { 383 struct protocol *p, *next, *prev; 384 385 prev = NULL; 386 for (p = protocols; p; p = next) { 387 next = p->next; 388 if (p == proto) { 389 if (prev) 390 prev->next = p->next; 391 else 392 protocols = p->next; 393 free(p); 394 } 395 } 396 } 397