sbin/dhclient/dispatch.c

   1 /*      $OpenBSD: dispatch.c,v 1.31 2004/09/21 04:07:03 david Exp $     */
   2
   3 /*-
   4  * SPDX-License-Identifier: BSD-3-Clause
   5  *
   6  * Copyright 2004 Henning Brauer <henning@openbsd.org>
   7  * Copyright (c) 1995, 1996, 1997, 1998, 1999
   8  * The Internet Software Consortium.   All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  *
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of The Internet Software Consortium nor the names
  20  *    of its contributors may be used to endorse or promote products derived
  21  *    from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
  24  * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  25  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  26  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  27  * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
  28  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  29  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  30  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  31  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  32  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  33  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  34  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  * This software has been written for the Internet Software Consortium
  38  * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
  39  * Enterprises.  To learn more about the Internet Software Consortium,
  40  * see ``http://www.vix.com/isc''.  To learn more about Vixie
  41  * Enterprises, see ``http://www.vix.com''.
  42  */
  43
  44 #include <sys/cdefs.h>
  45 __FBSDID("$FreeBSD$");
  46
  47 #include "dhcpd.h"
  48 #include "privsep.h"
  49
  50 #include <sys/ioctl.h>
  51
  52 #include <assert.h>
  53 #include <net/if_media.h>
  54 #include <ifaddrs.h>
  55 #include <poll.h>
  56
  57 /* Assert that pointer p is aligned to at least align bytes */
  58 #define assert_aligned(p, align) assert((((uintptr_t)p) & ((align) - 1)) == 0)
  59
  60 static struct protocol *protocols;
  61 static struct timeout *timeouts;
  62 static struct timeout *free_timeouts;
  63 static int interfaces_invalidated;
  64 void (*bootp_packet_handler)(struct interface_info *,
  65     struct dhcp_packet *, int, unsigned int,
  66     struct iaddr, struct hardware *);
  67
  68 static int interface_status(struct interface_info *ifinfo);
  69
  70 /*
  71  * Use getifaddrs() to get a list of all the attached interfaces.  For
  72  * each interface that's of type INET and not the loopback interface,
  73  * register that interface with the network I/O software, figure out
  74  * what subnet it's on, and add it to the list of interfaces.
  75  */
  76 void
  77 discover_interfaces(struct interface_info *iface)
  78 {
  79         struct ifaddrs *ifap, *ifa;
  80         struct ifreq *tif;
  81
  82         if (getifaddrs(&ifap) != 0)
  83                 error("getifaddrs failed");
  84
  85         for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
  86                 if ((ifa->ifa_flags & IFF_LOOPBACK) ||
  87                     (ifa->ifa_flags & IFF_POINTOPOINT) ||
  88                     (!(ifa->ifa_flags & IFF_UP)))
  89                         continue;
  90
  91                 if (strcmp(iface->name, ifa->ifa_name))
  92                         continue;
  93
  94                 /*
  95                  * If we have the capability, extract link information
  96                  * and record it in a linked list.
  97                  */
  98                 if (ifa->ifa_addr->sa_family == AF_LINK) {
  99                         struct sockaddr_dl *foo;
 100
 101                         /*
 102                          * The implementation of getifaddrs should guarantee
 103                          * this alignment
 104                          */
 105                         assert_aligned(ifa->ifa_addr,
 106                                        _Alignof(struct sockaddr_dl));
 107 #ifdef __clang__
 108 #pragma clang diagnostic push
 109 #pragma clang diagnostic ignored "-Wcast-align"
 110 #endif
 111                         foo = (struct sockaddr_dl *)ifa->ifa_addr;
 112 #ifdef __clang__
 113 #pragma clang diagnostic pop
 114 #endif
 115
 116                         iface->index = foo->sdl_index;
 117                         iface->hw_address.hlen = foo->sdl_alen;
 118                         iface->hw_address.htype = HTYPE_ETHER; /* XXX */
 119                         memcpy(iface->hw_address.haddr,
 120                             LLADDR(foo), foo->sdl_alen);
 121                 } else if (ifa->ifa_addr->sa_family == AF_INET) {
 122                         struct sockaddr_in foo;
 123                         struct iaddr addr;
 124
 125                         memcpy(&foo, ifa->ifa_addr, sizeof(foo));
 126                         if (foo.sin_addr.s_addr == htonl(INADDR_LOOPBACK))
 127                                 continue;
 128                         if (!iface->ifp) {
 129                                 if ((tif = calloc(1, sizeof(struct ifreq)))
 130                                     == NULL)
 131                                         error("no space to remember ifp");
 132                                 strlcpy(tif->ifr_name, ifa->ifa_name, IFNAMSIZ);
 133                                 memcpy(&tif->ifr_addr, ifa->ifa_addr,
 134                                     ifa->ifa_addr->sa_len);
 135                                 iface->ifp = tif;
 136                                 iface->primary_address = foo.sin_addr;
 137                         }
 138                         addr.len = 4;
 139                         memcpy(addr.iabuf, &foo.sin_addr.s_addr, addr.len);
 140                 }
 141         }
 142
 143         if (!iface->ifp)
 144                 error("%s: not found", iface->name);
 145
 146         /* Register the interface... */
 147         if_register_receive(iface);
 148         if_register_send(iface);
 149         add_protocol(iface->name, iface->rfdesc, got_one, iface);
 150         freeifaddrs(ifap);
 151 }
 152
 153 void
 154 reinitialize_interfaces(void)
 155 {
 156         interfaces_invalidated = 1;
 157 }
 158
 159 /*
 160  * Wait for packets to come in using poll().  When a packet comes in,
 161  * call receive_packet to receive the packet and possibly strip hardware
 162  * addressing information from it, and then call through the
 163  * bootp_packet_handler hook to try to do something with it.
 164  */
 165 void
 166 dispatch(void)
 167 {
 168         int count, live_interfaces, i, to_msec, nfds = 0;
 169         struct protocol *l;
 170         struct pollfd *fds;
 171         time_t howlong;
 172
 173         for (l = protocols; l; l = l->next)
 174                 nfds++;
 175
 176         fds = malloc(nfds * sizeof(struct pollfd));
 177         if (fds == NULL)
 178                 error("Can't allocate poll structures.");
 179
 180         do {
 181                 /*
 182                  * Call any expired timeouts, and then if there's still
 183                  * a timeout registered, time out the select call then.
 184                  */
 185 another:
 186                 if (timeouts) {
 187                         struct timeout *t;
 188
 189                         if (timeouts->when <= cur_time) {
 190                                 t = timeouts;
 191                                 timeouts = timeouts->next;
 192                                 (*(t->func))(t->what);
 193                                 t->next = free_timeouts;
 194                                 free_timeouts = t;
 195                                 goto another;
 196                         }
 197
 198                         /*
 199                          * Figure timeout in milliseconds, and check for
 200                          * potential overflow, so we can cram into an
 201                          * int for poll, while not polling with a
 202                          * negative timeout and blocking indefinitely.
 203                          */
 204                         howlong = timeouts->when - cur_time;
 205                         if (howlong > INT_MAX / 1000)
 206                                 howlong = INT_MAX / 1000;
 207                         to_msec = howlong * 1000;
 208                 } else
 209                         to_msec = -1;
 210
 211                 /* Set up the descriptors to be polled. */
 212                 live_interfaces = 0;
 213                 for (i = 0, l = protocols; l; l = l->next) {
 214                         struct interface_info *ip = l->local;
 215
 216                         if (ip == NULL || ip->dead)
 217                                 continue;
 218                         fds[i].fd = l->fd;
 219                         fds[i].events = POLLIN;
 220                         fds[i].revents = 0;
 221                         i++;
 222                         if (l->handler == got_one)
 223                                 live_interfaces++;
 224                 }
 225                 if (live_interfaces == 0)
 226                         error("No live interfaces to poll on - exiting.");
 227
 228                 /* Wait for a packet or a timeout... XXX */
 229                 count = poll(fds, nfds, to_msec);
 230
 231                 /* Not likely to be transitory... */
 232                 if (count == -1) {
 233                         if (errno == EAGAIN || errno == EINTR) {
 234                                 time(&cur_time);
 235                                 continue;
 236                         } else
 237                                 error("poll: %m");
 238                 }
 239
 240                 /* Get the current time... */
 241                 time(&cur_time);
 242
 243                 i = 0;
 244                 for (l = protocols; l; l = l->next) {
 245                         struct interface_info *ip;
 246                         ip = l->local;
 247                         if ((fds[i].revents & (POLLIN | POLLHUP))) {
 248                                 fds[i].revents = 0;
 249                                 if (ip && (l->handler != got_one ||
 250                                     !ip->dead))
 251                                         (*(l->handler))(l);
 252                                 if (interfaces_invalidated)
 253                                         break;
 254                         }
 255                         i++;
 256                 }
 257                 interfaces_invalidated = 0;
 258         } while (1);
 259 }
 260
 261
 262 void
 263 got_one(struct protocol *l)
 264 {
 265         struct sockaddr_in from;
 266         struct hardware hfrom;
 267         struct iaddr ifrom;
 268         ssize_t result;
 269         union {
 270                 /*
 271                  * Packet input buffer.  Must be as large as largest
 272                  * possible MTU.
 273                  */
 274                 unsigned char packbuf[4095];
 275                 struct dhcp_packet packet;
 276         } u;
 277         struct interface_info *ip = l->local;
 278
 279         if ((result = receive_packet(ip, u.packbuf, sizeof(u), &from,
 280             &hfrom)) == -1) {
 281                 warning("receive_packet failed on %s: %s", ip->name,
 282                     strerror(errno));
 283                 ip->errors++;
 284                 if ((!interface_status(ip)) ||
 285                     (ip->noifmedia && ip->errors > 20)) {
 286                         /* our interface has gone away. */
 287                         warning("Interface %s no longer appears valid.",
 288                             ip->name);
 289                         ip->dead = 1;
 290                         interfaces_invalidated = 1;
 291                         close(l->fd);
 292                         remove_protocol(l);
 293                         free(ip);
 294                 }
 295                 return;
 296         }
 297         if (result == 0)
 298                 return;
 299
 300         if (bootp_packet_handler) {
 301                 ifrom.len = 4;
 302                 memcpy(ifrom.iabuf, &from.sin_addr, ifrom.len);
 303
 304                 (*bootp_packet_handler)(ip, &u.packet, result,
 305                     from.sin_port, ifrom, &hfrom);
 306         }
 307 }
 308
 309 int
 310 interface_status(struct interface_info *ifinfo)
 311 {
 312         char *ifname = ifinfo->name;
 313         int ifsock = ifinfo->rfdesc;
 314         struct ifreq ifr;
 315         struct ifmediareq ifmr;
 316
 317         /* get interface flags */
 318         memset(&ifr, 0, sizeof(ifr));
 319         strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 320         if (ioctl(ifsock, SIOCGIFFLAGS, &ifr) < 0) {
 321                 cap_syslog(capsyslog, LOG_ERR, "ioctl(SIOCGIFFLAGS) on %s: %m",
 322                     ifname);
 323                 goto inactive;
 324         }
 325
 326         /*
 327          * if one of UP and RUNNING flags is dropped,
 328          * the interface is not active.
 329          */
 330         if ((ifr.ifr_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
 331                 goto inactive;
 332
 333         /* Next, check carrier on the interface, if possible */
 334         if (ifinfo->noifmedia)
 335                 goto active;
 336         memset(&ifmr, 0, sizeof(ifmr));
 337         strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
 338         if (ioctl(ifsock, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0) {
 339                 if (errno != EINVAL) {
 340                         cap_syslog(capsyslog, LOG_DEBUG,
 341                             "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
 342                         ifinfo->noifmedia = 1;
 343                         goto active;
 344                 }
 345                 /*
 346                  * EINVAL (or ENOTTY) simply means that the interface
 347                  * does not support the SIOCGIFMEDIA ioctl. We regard it alive.
 348                  */
 349                 ifinfo->noifmedia = 1;
 350                 goto active;
 351         }
 352         if (ifmr.ifm_status & IFM_AVALID) {
 353                 switch (ifmr.ifm_active & IFM_NMASK) {
 354                 case IFM_ETHER:
 355                 case IFM_IEEE80211:
 356                         if (ifmr.ifm_status & IFM_ACTIVE)
 357                                 goto active;
 358                         else
 359                                 goto inactive;
 360                         break;
 361                 default:
 362                         goto inactive;
 363                 }
 364         }
 365 inactive:
 366         return (0);
 367 active:
 368         return (1);
 369 }
 370
 371 void
 372 add_timeout(time_t when, void (*where)(void *), void *what)
 373 {
 374         struct timeout *t, *q;
 375
 376         /* See if this timeout supersedes an existing timeout. */
 377         t = NULL;
 378         for (q = timeouts; q; q = q->next) {
 379                 if (q->func == where && q->what == what) {
 380                         if (t)
 381                                 t->next = q->next;
 382                         else
 383                                 timeouts = q->next;
 384                         break;
 385                 }
 386                 t = q;
 387         }
 388
 389         /* If we didn't supersede a timeout, allocate a timeout
 390            structure now. */
 391         if (!q) {
 392                 if (free_timeouts) {
 393                         q = free_timeouts;
 394                         free_timeouts = q->next;
 395                         q->func = where;
 396                         q->what = what;
 397                 } else {
 398                         q = malloc(sizeof(struct timeout));
 399                         if (!q)
 400                                 error("Can't allocate timeout structure!");
 401                         q->func = where;
 402                         q->what = what;
 403                 }
 404         }
 405
 406         q->when = when;
 407
 408         /* Now sort this timeout into the timeout list. */
 409
 410         /* Beginning of list? */
 411         if (!timeouts || timeouts->when > q->when) {
 412                 q->next = timeouts;
 413                 timeouts = q;
 414                 return;
 415         }
 416
 417         /* Middle of list? */
 418         for (t = timeouts; t->next; t = t->next) {
 419                 if (t->next->when > q->when) {
 420                         q->next = t->next;
 421                         t->next = q;
 422                         return;
 423                 }
 424         }
 425
 426         /* End of list. */
 427         t->next = q;
 428         q->next = NULL;
 429 }
 430
 431 void
 432 cancel_timeout(void (*where)(void *), void *what)
 433 {
 434         struct timeout *t, *q;
 435
 436         /* Look for this timeout on the list, and unlink it if we find it. */
 437         t = NULL;
 438         for (q = timeouts; q; q = q->next) {
 439                 if (q->func == where && q->what == what) {
 440                         if (t)
 441                                 t->next = q->next;
 442                         else
 443                                 timeouts = q->next;
 444                         break;
 445                 }
 446                 t = q;
 447         }
 448
 449         /* If we found the timeout, put it on the free list. */
 450         if (q) {
 451                 q->next = free_timeouts;
 452                 free_timeouts = q;
 453         }
 454 }
 455
 456 /* Add a protocol to the list of protocols... */
 457 void
 458 add_protocol(const char *name, int fd, void (*handler)(struct protocol *),
 459     void *local)
 460 {
 461         struct protocol *p;
 462
 463         p = malloc(sizeof(*p));
 464         if (!p)
 465                 error("can't allocate protocol struct for %s", name);
 466
 467         p->fd = fd;
 468         p->handler = handler;
 469         p->local = local;
 470         p->next = protocols;
 471         protocols = p;
 472 }
 473
 474 void
 475 remove_protocol(struct protocol *proto)
 476 {
 477         struct protocol *p, *next;
 478
 479         for (p = protocols; p; p = next) {
 480                 next = p->next;
 481                 if (p == proto) {
 482                         protocols = p->next;
 483                         free(p);
 484                 }
 485         }
 486 }
 487
 488 int
 489 interface_link_status(char *ifname)
 490 {
 491         struct ifmediareq ifmr;
 492         int sock;
 493
 494         if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
 495                 error("Can't create socket");
 496
 497         memset(&ifmr, 0, sizeof(ifmr));
 498         strlcpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
 499         if (ioctl(sock, SIOCGIFMEDIA, (caddr_t)&ifmr) == -1) {
 500                 /* EINVAL -> link state unknown. treat as active */
 501                 if (errno != EINVAL)
 502                         cap_syslog(capsyslog, LOG_DEBUG,
 503                             "ioctl(SIOCGIFMEDIA) on %s: %m", ifname);
 504                 close(sock);
 505                 return (1);
 506         }
 507         close(sock);
 508
 509         if (ifmr.ifm_status & IFM_AVALID) {
 510                 switch (ifmr.ifm_active & IFM_NMASK) {
 511                 case IFM_ETHER:
 512                 case IFM_IEEE80211:
 513                         if (ifmr.ifm_status & IFM_ACTIVE)
 514                                 return (1);
 515                         else
 516                                 return (0);
 517                 }
 518         }
 519         return (1);
 520 }
 521
 522 void
 523 interface_set_mtu_unpriv(int privfd, u_int16_t mtu)
 524 {
 525         struct imsg_hdr hdr;
 526         struct buf *buf;
 527         int errs = 0;
 528
 529         hdr.code = IMSG_SET_INTERFACE_MTU;
 530         hdr.len = sizeof(hdr) +
 531                 sizeof(u_int16_t);
 532
 533         if ((buf = buf_open(hdr.len)) == NULL)
 534                 error("buf_open: %m");
 535
 536         errs += buf_add(buf, &hdr, sizeof(hdr));
 537         errs += buf_add(buf, &mtu, sizeof(mtu));
 538         if (errs)
 539                 error("buf_add: %m");
 540
 541         if (buf_close(privfd, buf) == -1)
 542                 error("buf_close: %m");
 543 }
 544
 545 void
 546 interface_set_mtu_priv(char *ifname, u_int16_t mtu)
 547 {
 548         struct ifreq ifr;
 549         int sock;
 550         u_int16_t old_mtu;
 551
 552         if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
 553                 error("Can't create socket");
 554
 555         memset(&ifr, 0, sizeof(ifr));
 556         old_mtu = 0;
 557
 558         strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 559
 560         if (ioctl(sock, SIOCGIFMTU, (caddr_t)&ifr) == -1)
 561                 warning("SIOCGIFMTU failed (%s): %s", ifname,
 562                         strerror(errno));
 563         else
 564                 old_mtu = ifr.ifr_mtu;
 565
 566         if (mtu != old_mtu) {
 567                 ifr.ifr_mtu = mtu;
 568
 569                 if (ioctl(sock, SIOCSIFMTU, &ifr) == -1)
 570                         warning("SIOCSIFMTU failed (%d): %s", mtu,
 571                                 strerror(errno));
 572         }
 573
 574         close(sock);
 575 }