sbin/dhclient/dispatch.c

   1 /*      $OpenBSD: dispatch.c,v 1.31 2004/09/21 04:07:03 david 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/cdefs.h>
  43 __FBSDID("$FreeBSD$");
  44
  45 #include "dhcpd.h"
  46 #include "privsep.h"
  47
  48 #include <sys/ioctl.h>
  49
  50 #include <assert.h>
  51 #include <net/if_media.h>
  52 #include <ifaddrs.h>
  53 #include <poll.h>
  54
  55 /* Assert that pointer p is aligned to at least align bytes */
  56 #define assert_aligned(p, align) assert((((uintptr_t)p) & ((align) - 1)) == 0)
  57
  58 struct protocol *protocols;
  59 struct timeout *timeouts;
  60 static struct timeout *free_timeouts;
  61 static int interfaces_invalidated;
  62 void (*bootp_packet_handler)(struct interface_info *,
  63     struct dhcp_packet *, int, unsigned int,
  64     struct iaddr, struct hardware *);
  65
  66 static int interface_status(struct interface_info *ifinfo);
  67
  68 /*
  69  * Use getifaddrs() to get a list of all the attached interfaces.  For
  70  * each interface that's of type INET and not the loopback interface,
  71  * register that interface with the network I/O software, figure out
  72  * what subnet it's on, and add it to the list of interfaces.
  73  */
  74 void
  75 discover_interfaces(struct interface_info *iface)
  76 {
  77         struct ifaddrs *ifap, *ifa;
  78         struct ifreq *tif;
  79
  80         if (getifaddrs(&ifap) != 0)
  81                 error("getifaddrs failed");
  82
  83         for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
  84                 if ((ifa->ifa_flags & IFF_LOOPBACK) ||
  85                     (ifa->ifa_flags & IFF_POINTOPOINT) ||
  86                     (!(ifa->ifa_flags & IFF_UP)))
  87                         continue;
  88
  89                 if (strcmp(iface->name, ifa->ifa_name))
  90                         continue;
  91
  92                 /*
  93                  * If we have the capability, extract link information
  94                  * and record it in a linked list.
  95                  */
  96                 if (ifa->ifa_addr->sa_family == AF_LINK) {
  97                         struct sockaddr_dl *foo;
  98
  99                         /*
 100                          * The implementation of getifaddrs should guarantee
 101                          * this alignment
 102                          */
 103                         assert_aligned(ifa->ifa_addr,
 104                                        _Alignof(struct sockaddr_dl));
 105 #ifdef __clang__
 106 #pragma clang diagnostic push
 107 #pragma clang diagnostic ignored "-Wcast-align"
 108 #endif
 109                         foo = (struct sockaddr_dl *)ifa->ifa_addr;
 110 #ifdef __clang__
 111 #pragma clang diagnostic pop
 112 #endif
 113
 114                         iface->index = foo->sdl_index;
 115                         iface->hw_address.hlen = foo->sdl_alen;
 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 sockaddr_in foo;
 121                         struct iaddr addr;
 122
 123                         memcpy(&foo, ifa->ifa_addr, sizeof(foo));
 124                         if (foo.sin_addr.s_addr == htonl(INADDR_LOOPBACK))
 125                                 continue;
 126                         if (!iface->ifp) {
 127                                 if ((tif = calloc(1, sizeof(struct ifreq)))
 128                                     == 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 void
 152 reinitialize_interfaces(void)
 153 {
 154         interfaces_invalidated = 1;
 155 }
 156
 157 /*
 158  * Wait for packets to come in using poll().  When a packet comes in,
 159  * call receive_packet to receive the packet and possibly strip hardware
 160  * addressing information from it, and then call through the
 161  * bootp_packet_handler hook to try to do something with it.
 162  */
 163 void
 164 dispatch(void)
 165 {
 166         int count, live_interfaces, i, to_msec, nfds = 0;
 167         struct protocol *l;
 168         struct pollfd *fds;
 169         time_t howlong;
 170
 171         for (l = protocols; l; l = l->next)
 172                 nfds++;
 173
 174         fds = malloc(nfds * sizeof(struct pollfd));
 175         if (fds == NULL)
 176                 error("Can't allocate poll structures.");
 177
 178         do {
 179                 /*
 180                  * Call any expired timeouts, and then if there's still
 181                  * a timeout registered, time out the select call then.
 182                  */
 183 another:
 184                 if (timeouts) {
 185                         struct timeout *t;
 186
 187                         if (timeouts->when <= cur_time) {
 188                                 t = timeouts;
 189                                 timeouts = timeouts->next;
 190                                 (*(t->func))(t->what);
 191                                 t->next = free_timeouts;
 192                                 free_timeouts = t;
 193                                 goto another;
 194                         }
 195
 196                         /*
 197                          * Figure timeout in milliseconds, and check for
 198                          * potential overflow, so we can cram into an
 199                          * int for poll, while not polling with a
 200                          * negative timeout and blocking indefinitely.
 201                          */
 202                         howlong = timeouts->when - cur_time;
 203                         if (howlong > INT_MAX / 1000)
 204                                 howlong = INT_MAX / 1000;
 205                         to_msec = howlong * 1000;
 206                 } else
 207                         to_msec = -1;
 208
 209                 /* Set up the descriptors to be polled. */
 210                 live_interfaces = 0;
 211                 for (i = 0, l = protocols; l; l = l->next) {
 212                         struct interface_info *ip = l->local;
 213
 214                         if (ip == NULL || ip->dead)
 215                                 continue;
 216                         fds[i].fd = l->fd;
 217                         fds[i].events = POLLIN;
 218                         fds[i].revents = 0;
 219                         i++;
 220                         if (l->handler == got_one)
 221                                 live_interfaces++;
 222                 }
 223                 if (live_interfaces == 0)
 224                         error("No live interfaces to poll on - exiting.");
 225
 226                 /* Wait for a packet or a timeout... XXX */
 227                 count = poll(fds, nfds, to_msec);
 228
 229                 /* Not likely to be transitory... */
 230                 if (count == -1) {
 231                         if (errno == EAGAIN || errno == EINTR) {
 232                                 time(&cur_time);
 233                                 continue;
 234                         } else
 235                                 error("poll: %m");
 236                 }
 237
 238                 /* Get the current time... */
 239                 time(&cur_time);
 240
 241                 i = 0;
 242                 for (l = protocols; l; l = l->next) {
 243                         struct interface_info *ip;
 244                         ip = l->local;
 245                         if ((fds[i].revents & (POLLIN | POLLHUP))) {
 246                                 fds[i].revents = 0;
 247                                 if (ip && (l->handler != got_one ||
 248                                     !ip->dead))
 249                                         (*(l->handler))(l);
 250                                 if (interfaces_invalidated)
 251                                         break;
 252                         }
 253                         i++;
 254                 }
 255                 interfaces_invalidated = 0;
 256         } while (1);
 257 }
 258
 259
 260 void
 261 got_one(struct protocol *l)
 262 {
 263         struct sockaddr_in from;
 264         struct hardware hfrom;
 265         struct iaddr ifrom;
 266         ssize_t result;
 267         union {
 268                 /*
 269                  * Packet input buffer.  Must be as large as largest
 270                  * possible MTU.
 271                  */
 272                 unsigned char packbuf[4095];
 273                 struct dhcp_packet packet;
 274         } u;
 275         struct interface_info *ip = l->local;
 276
 277         if ((result = receive_packet(ip, u.packbuf, sizeof(u), &from,
 278             &hfrom)) == -1) {
 279                 warning("receive_packet failed on %s: %s", ip->name,
 280                     strerror(errno));
 281                 ip->errors++;
 282                 if ((!interface_status(ip)) ||
 283                     (ip->noifmedia && ip->errors > 20)) {
 284                         /* our interface has gone away. */
 285                         warning("Interface %s no longer appears valid.",
 286                             ip->name);
 287                         ip->dead = 1;
 288                         interfaces_invalidated = 1;
 289                         close(l->fd);
 290                         remove_protocol(l);
 291                         free(ip);
 292                 }
 293                 return;
 294         }
 295         if (result == 0)
 296                 return;
 297
 298         if (bootp_packet_handler) {
 299                 ifrom.len = 4;
 300                 memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len);
 301
 302                 (*bootp_packet_handler)(ip, &u.packet, result,
 303                     from.sin_port, ifrom, &hfrom);
 304         }
 305 }
 306
 307 int
 308 interface_status(struct interface_info *ifinfo)
 309 {
 310         char *ifname = ifinfo->name;
 311         int ifsock = ifinfo->rfdesc;
 312         struct ifreq ifr;
 313         struct ifmediareq ifmr;
 314
 315         /* get interface flags */
 316         memset(&ifr, 0, sizeof(ifr));
 317         strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 318         if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) {
 319                 syslog(LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m", ifname);
 320                 goto inactive;
 321         }
 322
 323         /*
 324          * if one of UP and RUNNING flags is dropped,
 325          * the interface is not active.
 326          */
 327         if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
 328                 goto inactive;
 329
 330         /* Next, check carrier on the interface, if possible */
 331         if (ifinfo->noifmedia)
 332                 goto active;
 333         memset(&ifmr, 0, sizeof(ifmr));
 334         strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
 335         if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) {
 336                 if (errno != EINVAL) {
 337                         syslog(LOG_DEBUG, "ioctl(SIOCGIFMEDIA) on %s: %m",
 338                             ifname);
 339
 340                         ifinfo->noifmedia = 1;
 341                         goto active;
 342                 }
 343                 /*
 344                  * EINVAL (or ENOTTY) simply means that the interface
 345                  * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
 346                  */
 347                 ifinfo->noifmedia = 1;
 348                 goto active;
 349         }
 350         if (ifmr.ifm_status & IFM_AVALID) {
 351                 switch (ifmr.ifm_active & IFM_NMASK) {
 352                 case IFM_ETHER:
 353                 case IFM_IEEE80211:
 354                         if (ifmr.ifm_status & IFM_ACTIVE)
 355                                 goto active;
 356                         else
 357                                 goto inactive;
 358                         break;
 359                 default:
 360                         goto inactive;
 361                 }
 362         }
 363 inactive:
 364         return (0);
 365 active:
 366         return (1);
 367 }
 368
 369 void
 370 add_timeout(time_t when, void (*where)(void *), void *what)
 371 {
 372         struct timeout *t, *q;
 373
 374         /* See if this timeout supersedes an existing timeout. */
 375         t = NULL;
 376         for (q = timeouts; q; q = q->next) {
 377                 if (q->func == where && q->what == what) {
 378                         if (t)
 379                                 t->next = q->next;
 380                         else
 381                                 timeouts = q->next;
 382                         break;
 383                 }
 384                 t = q;
 385         }
 386
 387         /* If we didn't supersede a timeout, allocate a timeout
 388            structure now. */
 389         if (!q) {
 390                 if (free_timeouts) {
 391                         q = free_timeouts;
 392                         free_timeouts = q->next;
 393                         q->func = where;
 394                         q->what = what;
 395                 } else {
 396                         q = malloc(sizeof(struct timeout));
 397                         if (!q)
 398                                 error("Can't allocate timeout structure!");
 399                         q->func = where;
 400                         q->what = what;
 401                 }
 402         }
 403
 404         q->when = when;
 405
 406         /* Now sort this timeout into the timeout list. */
 407
 408         /* Beginning of list? */
 409         if (!timeouts || timeouts->when > q->when) {
 410                 q->next = timeouts;
 411                 timeouts = q;
 412                 return;
 413         }
 414
 415         /* Middle of list? */
 416         for (t = timeouts; t->next; t = t->next) {
 417                 if (t->next->when > q->when) {
 418                         q->next = t->next;
 419                         t->next = q;
 420                         return;
 421                 }
 422         }
 423
 424         /* End of list. */
 425         t->next = q;
 426         q->next = NULL;
 427 }
 428
 429 void
 430 cancel_timeout(void (*where)(void *), void *what)
 431 {
 432         struct timeout *t, *q;
 433
 434         /* Look for this timeout on the list, and unlink it if we find it. */
 435         t = NULL;
 436         for (q = timeouts; q; q = q->next) {
 437                 if (q->func == where && q->what == what) {
 438                         if (t)
 439                                 t->next = q->next;
 440                         else
 441                                 timeouts = q->next;
 442                         break;
 443                 }
 444                 t = q;
 445         }
 446
 447         /* If we found the timeout, put it on the free list. */
 448         if (q) {
 449                 q->next = free_timeouts;
 450                 free_timeouts = q;
 451         }
 452 }
 453
 454 /* Add a protocol to the list of protocols... */
 455 void
 456 add_protocol(const char *name, int fd, void (*handler)(struct protocol *),
 457     void *local)
 458 {
 459         struct protocol *p;
 460
 461         p = malloc(sizeof(*p));
 462         if (!p)
 463                 error("can't allocate protocol struct for %s", name);
 464
 465         p->fd = fd;
 466         p->handler = handler;
 467         p->local = local;
 468         p->next = protocols;
 469         protocols = p;
 470 }
 471
 472 void
 473 remove_protocol(struct protocol *proto)
 474 {
 475         struct protocol *p, *next;
 476
 477         for (p = protocols; p; p = next) {
 478                 next = p->next;
 479                 if (p == proto) {
 480                         protocols = p->next;
 481                         free(p);
 482                 }
 483         }
 484 }
 485
 486 int
 487 interface_link_status(char *ifname)
 488 {
 489         struct ifmediareq ifmr;
 490         int sock;
 491
 492         if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
 493                 error("Can't create socket");
 494
 495         memset(&ifmr, 0, sizeof(ifmr));
 496         strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
 497         if (ioctl(sock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) {
 498                 /* EINVAL -> link state unknown. treat as active */
 499                 if (errno != EINVAL)
 500                         syslog(LOG_DEBUG, "ioctl(SIOCGIFMEDIA) on %s: %m",
 501                             ifname);
 502                 close(sock);
 503                 return (1);
 504         }
 505         close(sock);
 506
 507         if (ifmr.ifm_status & IFM_AVALID) {
 508                 switch (ifmr.ifm_active & IFM_NMASK) {
 509                 case IFM_ETHER:
 510                 case IFM_IEEE80211:
 511                         if (ifmr.ifm_status & IFM_ACTIVE)
 512                                 return (1);
 513                         else
 514                                 return (0);
 515                 }
 516         }
 517         return (1);
 518 }
 519
 520 void
 521 interface_set_mtu_unpriv(int privfd, u_int16_t mtu)
 522 {
 523         struct imsg_hdr hdr;
 524         struct buf *buf;
 525         int errs = 0;
 526
 527         hdr.code = IMSG_SET_INTERFACE_MTU;
 528         hdr.len = sizeof(hdr) +
 529                 sizeof(u_int16_t);
 530
 531         if ((buf = buf_open(hdr.len)) == NULL)
 532                 error("buf_open: %m");
 533
 534         errs += buf_add(buf, &hdr, sizeof(hdr));
 535         errs += buf_add(buf, &mtu, sizeof(mtu));
 536         if (errs)
 537                 error("buf_add: %m");
 538
 539         if (buf_close(privfd, buf) == -1)
 540                 error("buf_close: %m");
 541 }
 542
 543 void
 544 interface_set_mtu_priv(char *ifname, u_int16_t mtu)
 545 {
 546         struct ifreq ifr;
 547         int sock;
 548         u_int16_t old_mtu;
 549
 550         if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
 551                 error("Can't create socket");
 552
 553         memset(&ifr, 0, sizeof(ifr));
 554         old_mtu = 0;
 555
 556         strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 557
 558         if (ioctl(sock, SIOCGIFMTU, (caddr_t)&ifr) == -1)
 559                 warning("SIOCGIFMTU failed (%s): %s", ifname,
 560                         strerror(errno));
 561         else
 562                 old_mtu = ifr.ifr_mtu;
 563
 564         if (mtu != old_mtu) {
 565                 ifr.ifr_mtu = mtu;
 566
 567                 if (ioctl(sock, SIOCSIFMTU, &ifr) == -1)
 568                         warning("SIOCSIFMTU failed (%d): %s", mtu,
 569                                 strerror(errno));
 570         }
 571
 572         close(sock);
 573 }