sbin/dhclient/dispatch.c

   1 /*     $OpenBSD: src/sbin/dhclient/dispatch.c,v 1.59 2012/10/11 08:05:05 sthen 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/ioctl.h>
  43
  44 #include <net/if_media.h>
  45
  46 #include <ifaddrs.h>
  47 #include <poll.h>
  48
  49 #include "dhcpd.h"
  50
  51 struct timeout timeout;
  52
  53 /*
  54  * Use getifaddrs() to get a list of all the attached interfaces.  Find
  55  * our interface on the list and store the interesting information about it.
  56  */
  57 void
  58 discover_interface(void)
  59 {
  60         struct ifaddrs *ifap, *ifa;
  61         struct ifreq *tif;
  62         int len = IFNAMSIZ + sizeof(struct sockaddr_storage);
  63
  64         if (getifaddrs(&ifap) != 0)
  65                 error("getifaddrs failed");
  66
  67         for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
  68                 if ((ifa->ifa_flags & IFF_LOOPBACK) ||
  69                     (ifa->ifa_flags & IFF_POINTOPOINT) ||
  70                     (!(ifa->ifa_flags & IFF_UP)))
  71                         continue;
  72
  73                 if (strcmp(ifi->name, ifa->ifa_name))
  74                         continue;
  75
  76                 /*
  77                  * If we have the capability, extract & save link information.
  78                  */
  79                 if (ifa->ifa_addr->sa_family == AF_LINK) {
  80                         struct sockaddr_dl *foo =
  81                             (struct sockaddr_dl *)ifa->ifa_addr;
  82
  83                         ifi->index = foo->sdl_index;
  84                         ifi->hw_address.hlen = foo->sdl_alen;
  85                         ifi->hw_address.htype = HTYPE_ETHER; /* XXX */
  86                         memcpy(ifi->hw_address.haddr,
  87                             LLADDR(foo), foo->sdl_alen);
  88                 }
  89                 if (!ifi->ifp) {
  90                         if ((tif = malloc(len)) == NULL)
  91                                 error("no space to remember ifp");
  92                         strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ);
  93                         ifi->ifp = tif;
  94                 }
  95         }
  96
  97         if (!ifi->ifp)
  98                 error("%s: not found", ifi->name);
  99
 100         /* Register the interface... */
 101         if_register_receive();
 102         if_register_send();
 103         freeifaddrs(ifap);
 104 }
 105
 106 /*
 107  * Loop waiting for packets, timeouts or routing messages.
 108  */
 109 void
 110 dispatch(void)
 111 {
 112         int count, to_msec;
 113         struct pollfd fds[2];
 114         time_t cur_time, howlong;
 115         void (*func)(void);
 116
 117         do {
 118                 /*
 119                  * Call expired timeout, and then if there's still
 120                  * a timeout registered, time out the select call then.
 121                  */
 122 another:
 123                 if (!ifi)
 124                         error("No interfaces available");
 125
 126                 if (timeout.func) {
 127                         time(&cur_time);
 128                         if (timeout.when <= cur_time) {
 129                                 func = timeout.func;
 130                                 cancel_timeout();
 131                                 (*(func))();
 132                                 goto another;
 133                         }
 134                         /*
 135                          * Figure timeout in milliseconds, and check for
 136                          * potential overflow, so we can cram into an
 137                          * int for poll, while not polling with a
 138                          * negative timeout and blocking indefinitely.
 139                          */
 140                         howlong = timeout.when - cur_time;
 141                         if (howlong > INT_MAX / 1000)
 142                                 howlong = INT_MAX / 1000;
 143                         to_msec = howlong * 1000;
 144                 } else
 145                         to_msec = -1;
 146
 147                 /* Set up the descriptors to be polled. */
 148                 if (!ifi || ifi->rfdesc == -1)
 149                         error("No live interface to poll on");
 150
 151                 fds[0].fd = ifi->rfdesc;
 152                 fds[1].fd = routefd; /* Could be -1, which will be ignored. */
 153                 fds[0].events = fds[1].events = POLLIN;
 154
 155                 /* Wait for a packet or a timeout... XXX */
 156                 count = poll(fds, 2, to_msec);
 157
 158                 /* Not likely to be transitory... */
 159                 if (count == -1) {
 160                         if (errno == EAGAIN || errno == EINTR) {
 161                                 continue;
 162                         } else
 163                                 error("poll: %m");
 164                 }
 165
 166                 if ((fds[0].revents & (POLLIN | POLLHUP))) {
 167                         /* XXX profmakx: I am not sure whether updating the linkstate
 168                           here is the best idea, but it being not up to date leads
 169                           to a busy loop.
 170                           Alternatively we can just remove the link state check since
 171                           the link state is checked in got_one() later on
 172                          */
 173                         ifi->linkstat = interface_status(ifi->name);
 174
 175                         if (ifi && ifi->linkstat && ifi->rfdesc != -1)
 176                                 got_one();
 177                 }
 178                 if ((fds[1].revents & (POLLIN | POLLHUP))) {
 179                         if (ifi)
 180                                 routehandler();
 181                 }
 182         } while (1);
 183 }
 184
 185 void
 186 got_one(void)
 187 {
 188         struct sockaddr_in from;
 189         struct hardware hfrom;
 190         struct iaddr ifrom;
 191         ssize_t result;
 192
 193         if ((result = receive_packet(&from, &hfrom)) == -1) {
 194                 warning("receive_packet failed on %s: %s", ifi->name,
 195                     strerror(errno));
 196                 ifi->errors++;
 197                 if ((!interface_status(ifi->name)) ||
 198                     (ifi->noifmedia && ifi->errors > 20)) {
 199                         /* our interface has gone away. */
 200                         error("Interface %s no longer appears valid.",
 201                             ifi->name);
 202                 }
 203                 return;
 204         }
 205         if (result == 0)
 206                 return;
 207
 208         ifrom.len = 4;
 209         memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len);
 210
 211         do_packet(result, from.sin_port, ifrom, &hfrom);
 212 }
 213
 214 /*
 215  * Normally its ok to force the interface link up, but don't do it
 216  * if it is an 80211 interface.
 217  */
 218 int
 219 interface_link_forceup(char *ifname)
 220 {
 221         struct ifreq ifr;
 222         struct ifmediareq ifmr;
 223         int sock;
 224
 225         if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
 226                 error("Can't create socket");
 227
 228         memset(&ifr, 0, sizeof(ifr));
 229         strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 230         if (ioctl(sock, SIOCGIFFLAGS, (caddr_t)&ifr) == -1) {
 231                 close(sock);
 232                 return (-1);
 233         }
 234         memset(&ifmr, 0, sizeof(ifmr));
 235         strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
 236         if (ioctl(sock, SIOCGIFMEDIA, (caddr_t)&ifmr) != -1) {
 237                 if (IFM_TYPE(ifmr.ifm_active) == IFM_IEEE80211) {
 238                         return 0;
 239                 }
 240         }
 241
 242         if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) {
 243                 ifr.ifr_flags |= IFF_UP;
 244                 if (ioctl(sock, SIOCSIFFLAGS, (caddr_t)&ifr) == -1) {
 245                         close(sock);
 246                         return (-1);
 247                 }
 248                 close(sock);
 249                 return (0);
 250         }
 251         close(sock);
 252         return (1);
 253 }
 254
 255 int
 256 interface_status(char *ifname)
 257 {
 258         struct ifreq ifr;
 259         struct ifmediareq ifmr;
 260         int sock;
 261
 262         if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
 263                 error("Can't create socket");
 264
 265         /* get interface flags */
 266         memset(&ifr, 0, sizeof(ifr));
 267         strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 268         if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1) {
 269                 error("ioctl(SIOCGIFFLAGS) on %s: %m", ifname);
 270         }
 271
 272         /*
 273          * if one of UP and RUNNING flags is dropped,
 274          * the interface is not active.
 275          */
 276         if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
 277                 goto inactive;
 278
 279         /* Next, check carrier on the interface, if possible */
 280         if (ifi->noifmedia)
 281                 goto active;
 282         memset(&ifmr, 0, sizeof(ifmr));
 283         strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
 284         if (ioctl(sock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) {
 285                 /*
 286                  * EINVAL or ENOTTY simply means that the interface
 287                  * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
 288                  */
 289 #ifdef DEBUG
 290                 if (errno != EINVAL && errno != ENOTTY)
 291                         debug("ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
 292 #endif
 293                 ifi->noifmedia = 1;
 294                 goto active;
 295         }
 296         if (ifmr.ifm_status & IFM_AVALID) {
 297                 if (ifmr.ifm_status & IFM_ACTIVE)
 298                         goto active;
 299                 else
 300                         goto inactive;
 301         }
 302
 303         /* Assume 'active' if IFM_AVALID is not set. */
 304
 305 active:
 306         close(sock);
 307         return (1);
 308 inactive:
 309         close(sock);
 310         return (0);
 311 }
 312
 313 void
 314 set_timeout(time_t when, void (*where)(void))
 315 {
 316         timeout.when = when;
 317         timeout.func = where;
 318 }
 319
 320 void
 321 set_timeout_interval(time_t secs, void (*where)(void))
 322 {
 323         timeout.when = time(NULL) + secs;
 324         timeout.func = where;
 325 }
 326
 327 void
 328 cancel_timeout(void)
 329 {
 330         timeout.when = 0;
 331         timeout.func = NULL;
 332 }
 333
 334 int
 335 subnet_exists(struct client_lease *l)
 336 {
 337         struct ifaddrs *ifap, *ifa;
 338         in_addr_t mymask, myaddr, mynet, hismask, hisaddr, hisnet;
 339
 340         bcopy(l->options[DHO_SUBNET_MASK].data, &mymask, 4);
 341         bcopy(l->address.iabuf, &myaddr, 4);
 342         mynet = mymask & myaddr;
 343
 344         if (getifaddrs(&ifap) != 0)
 345                 error("getifaddrs failed");
 346
 347         for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
 348                 if (strcmp(ifi->name, ifa->ifa_name) == 0)
 349                         continue;
 350
 351                 if (ifa->ifa_addr->sa_family != AF_INET)
 352                         continue;
 353
 354                 hismask = ((struct sockaddr_in *)ifa->ifa_netmask)->
 355                     sin_addr.s_addr;
 356                 hisaddr = ((struct sockaddr_in *)ifa->ifa_addr)->
 357                     sin_addr.s_addr;
 358                 hisnet = hisaddr & hismask;
 359
 360                 if (hisnet == 0)
 361                         continue;
 362
 363                 /* Would his packets go out *my* interface? */
 364                 if (mynet == (hisaddr & mymask)) {
 365                         note("interface %s already has the offered subnet!",
 366                             ifa->ifa_name);
 367                         return (1);
 368                 }
 369
 370                 /* Would my packets go out *his* interface? */
 371                 if (hisnet == (myaddr & hismask)) {
 372                         note("interface %s already has the offered subnet!",
 373                             ifa->ifa_name);
 374                         return (1);
 375                 }
 376         }
 377
 378         freeifaddrs(ifap);
 379
 380         return (0);
 381 }