networking/udhcp/dhcpc.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * udhcp DHCP client
   4  *
   5  * Russ Dill <Russ.Dill@asu.edu> July 2001
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21 #include <syslog.h>
  22 /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
  23 #define WANT_PIDFILE 1
  24 #include "common.h"
  25 #include "dhcpd.h"
  26 #include "dhcpc.h"
  27
  28 #include <asm/types.h>
  29 #if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined(_NEWLIB_VERSION)
  30 # include <netpacket/packet.h>
  31 # include <net/ethernet.h>
  32 #else
  33 # include <linux/if_packet.h>
  34 # include <linux/if_ether.h>
  35 #endif
  36 #include <linux/filter.h>
  37
  38 /* struct client_config_t client_config is in bb_common_bufsiz1 */
  39
  40
  41 /*** Script execution code ***/
  42
  43 /* get a rough idea of how long an option will be (rounding up...) */
  44 static const uint8_t len_of_option_as_string[] = {
  45         [OPTION_IP] =           sizeof("255.255.255.255 "),
  46         [OPTION_IP_PAIR] =      sizeof("255.255.255.255 ") * 2,
  47         [OPTION_STATIC_ROUTES]= sizeof("255.255.255.255/32 255.255.255.255 "),
  48         [OPTION_STRING] =       1,
  49 #if ENABLE_FEATURE_UDHCP_RFC3397
  50         [OPTION_STR1035] =      1,
  51 #endif
  52 //      [OPTION_BOOLEAN] =      sizeof("yes "),
  53         [OPTION_U8] =           sizeof("255 "),
  54         [OPTION_U16] =          sizeof("65535 "),
  55 //      [OPTION_S16] =          sizeof("-32768 "),
  56         [OPTION_U32] =          sizeof("4294967295 "),
  57         [OPTION_S32] =          sizeof("-2147483684 "),
  58 };
  59
  60 /* note: ip is a pointer to an IP in network order, possibly misaliged */
  61 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
  62 {
  63         return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
  64 }
  65
  66 /* really simple implementation, just count the bits */
  67 static int mton(uint32_t mask)
  68 {
  69         int i = 0;
  70         mask = ntohl(mask); /* 111110000-like bit pattern */
  71         while (mask) {
  72                 i++;
  73                 mask <<= 1;
  74         }
  75         return i;
  76 }
  77
  78 /* Create "opt_name=opt_value" string */
  79 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_option *type_p, const char *opt_name)
  80 {
  81         unsigned upper_length;
  82         int len, type, optlen;
  83         uint16_t val_u16;
  84         uint32_t val_u32;
  85         int32_t val_s32;
  86         char *dest, *ret;
  87
  88         /* option points to OPT_DATA, need to go back and get OPT_LEN */
  89         len = option[OPT_LEN - OPT_DATA];
  90         type = type_p->flags & OPTION_TYPE_MASK;
  91         optlen = dhcp_option_lengths[type];
  92         upper_length = len_of_option_as_string[type] * (len / optlen);
  93
  94         dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
  95         dest += sprintf(ret, "%s=", opt_name);
  96
  97         while (len >= optlen) {
  98                 switch (type) {
  99                 case OPTION_IP_PAIR:
 100                         dest += sprint_nip(dest, "", option);
 101                         *dest++ = '/';
 102                         option += 4;
 103                         optlen = 4;
 104                 case OPTION_IP:
 105                         dest += sprint_nip(dest, "", option);
 106 // TODO: it can be a list only if (type_p->flags & OPTION_LIST).
 107 // Should we bail out/warn if we see multi-ip option which is
 108 // not allowed to be such? For example, DHCP_BROADCAST...
 109                         break;
 110 //              case OPTION_BOOLEAN:
 111 //                      dest += sprintf(dest, *option ? "yes" : "no");
 112 //                      break;
 113                 case OPTION_U8:
 114                         dest += sprintf(dest, "%u", *option);
 115                         break;
 116                 case OPTION_U16:
 117                         move_from_unaligned16(val_u16, option);
 118                         dest += sprintf(dest, "%u", ntohs(val_u16));
 119                         break;
 120 //              case OPTION_S16: {
 121 //                      int16_t val_s16;
 122 //                      move_from_unaligned16(val_s16, option);
 123 //                      dest += sprintf(dest, "%d", ntohs(val_s16));
 124 //                      break;
 125 //              }
 126                 case OPTION_U32:
 127                         move_from_unaligned32(val_u32, option);
 128                         dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
 129                         break;
 130                 case OPTION_S32:
 131                         move_from_unaligned32(val_s32, option);
 132                         dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
 133                         break;
 134                 case OPTION_STRING:
 135                         memcpy(dest, option, len);
 136                         dest[len] = '\0';
 137                         return ret;      /* Short circuit this case */
 138                 case OPTION_STATIC_ROUTES: {
 139                         /* Option binary format:
 140                          * mask [one byte, 0..32]
 141                          * ip [big endian, 0..4 bytes depending on mask]
 142                          * router [big endian, 4 bytes]
 143                          * may be repeated
 144                          *
 145                          * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
 146                          */
 147                         const char *pfx = "";
 148
 149                         while (len >= 1 + 4) { /* mask + 0-byte ip + router */
 150                                 uint32_t nip;
 151                                 uint8_t *p;
 152                                 unsigned mask;
 153                                 int bytes;
 154
 155                                 mask = *option++;
 156                                 if (mask > 32)
 157                                         break;
 158                                 len--;
 159
 160                                 nip = 0;
 161                                 p = (void*) &nip;
 162                                 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
 163                                 while (--bytes >= 0) {
 164                                         *p++ = *option++;
 165                                         len--;
 166                                 }
 167                                 if (len < 4)
 168                                         break;
 169
 170                                 /* print ip/mask */
 171                                 dest += sprint_nip(dest, pfx, (void*) &nip);
 172                                 pfx = " ";
 173                                 dest += sprintf(dest, "/%u ", mask);
 174                                 /* print router */
 175                                 dest += sprint_nip(dest, "", option);
 176                                 option += 4;
 177                                 len -= 4;
 178                         }
 179
 180                         return ret;
 181                 }
 182 #if ENABLE_FEATURE_UDHCP_RFC3397
 183                 case OPTION_STR1035:
 184                         /* unpack option into dest; use ret for prefix (i.e., "optname=") */
 185                         dest = dname_dec(option, len, ret);
 186                         if (dest) {
 187                                 free(ret);
 188                                 return dest;
 189                         }
 190                         /* error. return "optname=" string */
 191                         return ret;
 192 #endif
 193                 }
 194                 option += optlen;
 195                 len -= optlen;
 196                 if (len <= 0)
 197                         break;
 198                 *dest++ = ' ';
 199                 *dest = '\0';
 200         }
 201         return ret;
 202 }
 203
 204 /* put all the parameters into the environment */
 205 static char **fill_envp(struct dhcp_packet *packet)
 206 {
 207         int num_options = 0;
 208         int i;
 209         char **envp, **curr;
 210         const char *opt_name;
 211         uint8_t *temp;
 212         uint8_t over = 0;
 213
 214         if (packet) {
 215                 for (i = 0; dhcp_options[i].code; i++) {
 216                         if (udhcp_get_option(packet, dhcp_options[i].code)) {
 217                                 num_options++;
 218                                 if (dhcp_options[i].code == DHCP_SUBNET)
 219                                         num_options++; /* for mton */
 220                         }
 221                 }
 222                 if (packet->siaddr_nip)
 223                         num_options++;
 224                 temp = udhcp_get_option(packet, DHCP_OPTION_OVERLOAD);
 225                 if (temp)
 226                         over = *temp;
 227                 if (!(over & FILE_FIELD) && packet->file[0])
 228                         num_options++;
 229                 if (!(over & SNAME_FIELD) && packet->sname[0])
 230                         num_options++;
 231         }
 232
 233         curr = envp = xzalloc(sizeof(char *) * (num_options + 3));
 234         *curr = xasprintf("interface=%s", client_config.interface);
 235         putenv(*curr++);
 236
 237         if (packet == NULL)
 238                 return envp;
 239
 240         *curr = xmalloc(sizeof("ip=255.255.255.255"));
 241         sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
 242         putenv(*curr++);
 243
 244         opt_name = dhcp_option_strings;
 245         i = 0;
 246         while (*opt_name) {
 247                 temp = udhcp_get_option(packet, dhcp_options[i].code);
 248                 if (!temp)
 249                         goto next;
 250                 *curr = xmalloc_optname_optval(temp, &dhcp_options[i], opt_name);
 251                 putenv(*curr++);
 252
 253                 /* Fill in a subnet bits option for things like /24 */
 254                 if (dhcp_options[i].code == DHCP_SUBNET) {
 255                         uint32_t subnet;
 256                         move_from_unaligned32(subnet, temp);
 257                         *curr = xasprintf("mask=%d", mton(subnet));
 258                         putenv(*curr++);
 259                 }
 260  next:
 261                 opt_name += strlen(opt_name) + 1;
 262                 i++;
 263         }
 264         if (packet->siaddr_nip) {
 265                 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
 266                 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
 267                 putenv(*curr++);
 268         }
 269         if (!(over & FILE_FIELD) && packet->file[0]) {
 270                 /* watch out for invalid packets */
 271                 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
 272                 putenv(*curr++);
 273         }
 274         if (!(over & SNAME_FIELD) && packet->sname[0]) {
 275                 /* watch out for invalid packets */
 276                 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
 277                 putenv(*curr++);
 278         }
 279         return envp;
 280 }
 281
 282 /* Call a script with a par file and env vars */
 283 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
 284 {
 285         char **envp, **curr;
 286         char *argv[3];
 287
 288         if (client_config.script == NULL)
 289                 return;
 290
 291         envp = fill_envp(packet);
 292
 293         /* call script */
 294         log1("Executing %s %s", client_config.script, name);
 295         argv[0] = (char*) client_config.script;
 296         argv[1] = (char*) name;
 297         argv[2] = NULL;
 298         spawn_and_wait(argv);
 299
 300         for (curr = envp; *curr; curr++) {
 301                 log2(" %s", *curr);
 302                 bb_unsetenv(*curr);
 303                 free(*curr);
 304         }
 305         free(envp);
 306 }
 307
 308
 309 /*** Sending/receiving packets ***/
 310
 311 static ALWAYS_INLINE uint32_t random_xid(void)
 312 {
 313         return rand();
 314 }
 315
 316 /* Initialize the packet with the proper defaults */
 317 static void init_packet(struct dhcp_packet *packet, char type)
 318 {
 319         udhcp_init_header(packet, type);
 320         memcpy(packet->chaddr, client_config.client_mac, 6);
 321         if (client_config.clientid)
 322                 udhcp_add_binary_option(packet, client_config.clientid);
 323         if (client_config.hostname)
 324                 udhcp_add_binary_option(packet, client_config.hostname);
 325         if (client_config.fqdn)
 326                 udhcp_add_binary_option(packet, client_config.fqdn);
 327         if (type != DHCPDECLINE
 328          && type != DHCPRELEASE
 329          && client_config.vendorclass
 330         ) {
 331                 udhcp_add_binary_option(packet, client_config.vendorclass);
 332         }
 333 }
 334
 335 static void add_client_options(struct dhcp_packet *packet)
 336 {
 337         /* Add a "param req" option with the list of options we'd like to have
 338          * from stubborn DHCP servers. Pull the data from the struct in common.c.
 339          * No bounds checking because it goes towards the head of the packet. */
 340         uint8_t c;
 341         int end = udhcp_end_option(packet->options);
 342         int i, len = 0;
 343
 344         for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
 345                 if ((   (dhcp_options[i].flags & OPTION_REQ)
 346                      && !client_config.no_default_options
 347                     )
 348                  || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
 349                 ) {
 350                         packet->options[end + OPT_DATA + len] = c;
 351                         len++;
 352                 }
 353         }
 354         if (len) {
 355                 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
 356                 packet->options[end + OPT_LEN] = len;
 357                 packet->options[end + OPT_DATA + len] = DHCP_END;
 358         }
 359
 360         /* Add -x options if any */
 361         {
 362                 struct option_set *curr = client_config.options;
 363                 while (curr) {
 364                         udhcp_add_binary_option(packet, curr->data);
 365                         curr = curr->next;
 366                 }
 367 //              if (client_config.sname)
 368 //                      strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
 369 //              if (client_config.boot_file)
 370 //                      strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
 371         }
 372 }
 373
 374 /* RFC 2131
 375  * 4.4.4 Use of broadcast and unicast
 376  *
 377  * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
 378  * messages, unless the client knows the address of a DHCP server.
 379  * The client unicasts DHCPRELEASE messages to the server. Because
 380  * the client is declining the use of the IP address supplied by the server,
 381  * the client broadcasts DHCPDECLINE messages.
 382  *
 383  * When the DHCP client knows the address of a DHCP server, in either
 384  * INIT or REBOOTING state, the client may use that address
 385  * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
 386  * The client may also use unicast to send DHCPINFORM messages
 387  * to a known DHCP server. If the client receives no response to DHCP
 388  * messages sent to the IP address of a known DHCP server, the DHCP
 389  * client reverts to using the IP broadcast address.
 390  */
 391
 392 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
 393 {
 394         return udhcp_send_raw_packet(packet,
 395                 /*src*/ INADDR_ANY, CLIENT_PORT,
 396                 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
 397                 client_config.ifindex);
 398 }
 399
 400 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
 401 static int send_discover(uint32_t xid, uint32_t requested)
 402 {
 403         struct dhcp_packet packet;
 404
 405         init_packet(&packet, DHCPDISCOVER);
 406         packet.xid = xid;
 407         if (requested)
 408                 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 409         /* Explicitly saying that we want RFC-compliant packets helps
 410          * some buggy DHCP servers to NOT send bigger packets */
 411         udhcp_add_simple_option(&packet, DHCP_MAX_SIZE, htons(576));
 412         add_client_options(&packet);
 413
 414         bb_info_msg("Sending discover...");
 415         return raw_bcast_from_client_config_ifindex(&packet);
 416 }
 417
 418 /* Broadcast a DHCP request message */
 419 /* RFC 2131 3.1 paragraph 3:
 420  * "The client _broadcasts_ a DHCPREQUEST message..."
 421  */
 422 static int send_select(uint32_t xid, uint32_t server, uint32_t requested)
 423 {
 424         struct dhcp_packet packet;
 425         struct in_addr addr;
 426
 427         init_packet(&packet, DHCPREQUEST);
 428         packet.xid = xid;
 429         udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 430         udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 431         add_client_options(&packet);
 432
 433         addr.s_addr = requested;
 434         bb_info_msg("Sending select for %s...", inet_ntoa(addr));
 435         return raw_bcast_from_client_config_ifindex(&packet);
 436 }
 437
 438 /* Unicast or broadcast a DHCP renew message */
 439 static int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
 440 {
 441         struct dhcp_packet packet;
 442
 443         init_packet(&packet, DHCPREQUEST);
 444         packet.xid = xid;
 445         packet.ciaddr = ciaddr;
 446         add_client_options(&packet);
 447
 448         bb_info_msg("Sending renew...");
 449         if (server)
 450                 return udhcp_send_kernel_packet(&packet,
 451                         ciaddr, CLIENT_PORT,
 452                         server, SERVER_PORT);
 453         return raw_bcast_from_client_config_ifindex(&packet);
 454 }
 455
 456 #if ENABLE_FEATURE_UDHCPC_ARPING
 457 /* Broadcast a DHCP decline message */
 458 static int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
 459 {
 460         struct dhcp_packet packet;
 461
 462         init_packet(&packet, DHCPDECLINE);
 463         packet.xid = xid;
 464         udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 465         udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 466
 467         bb_info_msg("Sending decline...");
 468         return raw_bcast_from_client_config_ifindex(&packet);
 469 }
 470 #endif
 471
 472 /* Unicast a DHCP release message */
 473 static int send_release(uint32_t server, uint32_t ciaddr)
 474 {
 475         struct dhcp_packet packet;
 476
 477         init_packet(&packet, DHCPRELEASE);
 478         packet.xid = random_xid();
 479         packet.ciaddr = ciaddr;
 480
 481         udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 482
 483         bb_info_msg("Sending release...");
 484         return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
 485 }
 486
 487 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
 488 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
 489 {
 490         int bytes;
 491         struct ip_udp_dhcp_packet packet;
 492         uint16_t check;
 493
 494         memset(&packet, 0, sizeof(packet));
 495         bytes = safe_read(fd, &packet, sizeof(packet));
 496         if (bytes < 0) {
 497                 log1("Packet read error, ignoring");
 498                 /* NB: possible down interface, etc. Caller should pause. */
 499                 return bytes; /* returns -1 */
 500         }
 501
 502         if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
 503                 log1("Packet is too short, ignoring");
 504                 return -2;
 505         }
 506
 507         if (bytes < ntohs(packet.ip.tot_len)) {
 508                 /* packet is bigger than sizeof(packet), we did partial read */
 509                 log1("Oversized packet, ignoring");
 510                 return -2;
 511         }
 512
 513         /* ignore any extra garbage bytes */
 514         bytes = ntohs(packet.ip.tot_len);
 515
 516         /* make sure its the right packet for us, and that it passes sanity checks */
 517         if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
 518          || packet.ip.ihl != (sizeof(packet.ip) >> 2)
 519          || packet.udp.dest != htons(CLIENT_PORT)
 520         /* || bytes > (int) sizeof(packet) - can't happen */
 521          || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
 522         ) {
 523                 log1("Unrelated/bogus packet, ignoring");
 524                 return -2;
 525         }
 526
 527         /* verify IP checksum */
 528         check = packet.ip.check;
 529         packet.ip.check = 0;
 530         if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
 531                 log1("Bad IP header checksum, ignoring");
 532                 return -2;
 533         }
 534
 535         /* verify UDP checksum. IP header has to be modified for this */
 536         memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
 537         /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
 538         packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
 539         check = packet.udp.check;
 540         packet.udp.check = 0;
 541         if (check && check != udhcp_checksum(&packet, bytes)) {
 542                 log1("Packet with bad UDP checksum received, ignoring");
 543                 return -2;
 544         }
 545
 546         memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
 547
 548         if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
 549                 bb_info_msg("Packet with bad magic, ignoring");
 550                 return -2;
 551         }
 552         log1("Got valid DHCP packet");
 553         udhcp_dump_packet(dhcp_pkt);
 554         return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
 555 }
 556
 557
 558 /*** Main ***/
 559
 560 static int sockfd = -1;
 561
 562 #define LISTEN_NONE   0
 563 #define LISTEN_KERNEL 1
 564 #define LISTEN_RAW    2
 565 static smallint listen_mode;
 566
 567 /* initial state: (re)start DHCP negotiation */
 568 #define INIT_SELECTING  0
 569 /* discover was sent, DHCPOFFER reply received */
 570 #define REQUESTING      1
 571 /* select/renew was sent, DHCPACK reply received */
 572 #define BOUND           2
 573 /* half of lease passed, want to renew it by sending unicast renew requests */
 574 #define RENEWING        3
 575 /* renew requests were not answered, lease is almost over, send broadcast renew */
 576 #define REBINDING       4
 577 /* manually requested renew (SIGUSR1) */
 578 #define RENEW_REQUESTED 5
 579 /* release, possibly manually requested (SIGUSR2) */
 580 #define RELEASED        6
 581 static smallint state;
 582
 583 static int udhcp_raw_socket(int ifindex)
 584 {
 585         int fd;
 586         struct sockaddr_ll sock;
 587
 588         /*
 589          * Comment:
 590          *
 591          *      I've selected not to see LL header, so BPF doesn't see it, too.
 592          *      The filter may also pass non-IP and non-ARP packets, but we do
 593          *      a more complete check when receiving the message in userspace.
 594          *
 595          * and filter shamelessly stolen from:
 596          *
 597          *      http://www.flamewarmaster.de/software/dhcpclient/
 598          *
 599          * There are a few other interesting ideas on that page (look under
 600          * "Motivation").  Use of netlink events is most interesting.  Think
 601          * of various network servers listening for events and reconfiguring.
 602          * That would obsolete sending HUP signals and/or make use of restarts.
 603          *
 604          * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
 605          * License: GPL v2.
 606          *
 607          * TODO: make conditional?
 608          */
 609 #define SERVER_AND_CLIENT_PORTS  ((67 << 16) + 68)
 610         static const struct sock_filter filter_instr[] = {
 611                 /* check for udp */
 612                 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
 613                 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0),     /* L5, L1, is UDP? */
 614                 /* ugly check for arp on ethernet-like and IPv4 */
 615                 BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2),                      /* L1: */
 616                 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4),      /* L3, L4 */
 617                 /* skip IP header */
 618                 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),                     /* L5: */
 619                 /* check udp source and destination ports */
 620                 BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0),
 621                 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1), /* L3, L4 */
 622                 /* returns */
 623                 BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ),                   /* L3: pass */
 624                 BPF_STMT(BPF_RET|BPF_K, 0),                             /* L4: reject */
 625         };
 626         static const struct sock_fprog filter_prog = {
 627                 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
 628                 /* casting const away: */
 629                 .filter = (struct sock_filter *) filter_instr,
 630         };
 631
 632         log1("Opening raw socket on ifindex %d", ifindex); //log2?
 633
 634         fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
 635         log1("Got raw socket fd %d", fd); //log2?
 636
 637         if (SERVER_PORT == 67 && CLIENT_PORT == 68) {
 638                 /* Use only if standard ports are in use */
 639                 /* Ignoring error (kernel may lack support for this) */
 640                 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
 641                                 sizeof(filter_prog)) >= 0)
 642                         log1("Attached filter to raw socket fd %d", fd); // log?
 643         }
 644
 645         sock.sll_family = AF_PACKET;
 646         sock.sll_protocol = htons(ETH_P_IP);
 647         sock.sll_ifindex = ifindex;
 648         xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
 649         log1("Created raw socket");
 650
 651         return fd;
 652 }
 653
 654 static void change_listen_mode(int new_mode)
 655 {
 656         log1("Entering listen mode: %s",
 657                 new_mode != LISTEN_NONE
 658                         ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
 659                         : "none"
 660         );
 661
 662         listen_mode = new_mode;
 663         if (sockfd >= 0) {
 664                 close(sockfd);
 665                 sockfd = -1;
 666         }
 667         if (new_mode == LISTEN_KERNEL)
 668                 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
 669         else if (new_mode != LISTEN_NONE)
 670                 sockfd = udhcp_raw_socket(client_config.ifindex);
 671         /* else LISTEN_NONE: sockfd stays closed */
 672 }
 673
 674 static void perform_renew(void)
 675 {
 676         bb_info_msg("Performing a DHCP renew");
 677         switch (state) {
 678         case BOUND:
 679                 change_listen_mode(LISTEN_KERNEL);
 680         case RENEWING:
 681         case REBINDING:
 682                 state = RENEW_REQUESTED;
 683                 break;
 684         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
 685                 udhcp_run_script(NULL, "deconfig");
 686         case REQUESTING:
 687         case RELEASED:
 688                 change_listen_mode(LISTEN_RAW);
 689                 state = INIT_SELECTING;
 690                 break;
 691         case INIT_SELECTING:
 692                 break;
 693         }
 694 }
 695
 696 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
 697 {
 698         char buffer[sizeof("255.255.255.255")];
 699         struct in_addr temp_addr;
 700
 701         /* send release packet */
 702         if (state == BOUND || state == RENEWING || state == REBINDING) {
 703                 temp_addr.s_addr = server_addr;
 704                 strcpy(buffer, inet_ntoa(temp_addr));
 705                 temp_addr.s_addr = requested_ip;
 706                 bb_info_msg("Unicasting a release of %s to %s",
 707                                 inet_ntoa(temp_addr), buffer);
 708                 send_release(server_addr, requested_ip); /* unicast */
 709                 udhcp_run_script(NULL, "deconfig");
 710         }
 711         bb_info_msg("Entering released state");
 712
 713         change_listen_mode(LISTEN_NONE);
 714         state = RELEASED;
 715 }
 716
 717 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
 718 {
 719         uint8_t *storage;
 720         int len = strnlen(str, 255);
 721         storage = xzalloc(len + extra + OPT_DATA);
 722         storage[OPT_CODE] = code;
 723         storage[OPT_LEN] = len + extra;
 724         memcpy(storage + extra + OPT_DATA, str, len);
 725         return storage;
 726 }
 727
 728 #if BB_MMU
 729 static void client_background(void)
 730 {
 731         bb_daemonize(0);
 732         logmode &= ~LOGMODE_STDIO;
 733         /* rewrite pidfile, as our pid is different now */
 734         write_pidfile(client_config.pidfile);
 735 }
 736 #endif
 737
 738 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 739 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 740 {
 741         uint8_t *temp, *message;
 742         const char *str_c, *str_V, *str_h, *str_F, *str_r;
 743         IF_FEATURE_UDHCP_PORT(char *str_P;)
 744         llist_t *list_O = NULL;
 745         llist_t *list_x = NULL;
 746         int tryagain_timeout = 20;
 747         int discover_timeout = 3;
 748         int discover_retries = 3;
 749         uint32_t server_addr = server_addr; /* for compiler */
 750         uint32_t requested_ip = 0;
 751         uint32_t xid = 0;
 752         uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
 753         int packet_num;
 754         int timeout; /* must be signed */
 755         unsigned already_waited_sec;
 756         unsigned opt;
 757         int max_fd;
 758         int retval;
 759         struct timeval tv;
 760         struct dhcp_packet packet;
 761         fd_set rfds;
 762
 763 #if ENABLE_LONG_OPTS
 764         static const char udhcpc_longopts[] ALIGN1 =
 765                 "clientid\0"       Required_argument "c"
 766                 "clientid-none\0"  No_argument       "C"
 767                 "vendorclass\0"    Required_argument "V"
 768                 "hostname\0"       Required_argument "H"
 769                 "fqdn\0"           Required_argument "F"
 770                 "interface\0"      Required_argument "i"
 771                 "now\0"            No_argument       "n"
 772                 "pidfile\0"        Required_argument "p"
 773                 "quit\0"           No_argument       "q"
 774                 "release\0"        No_argument       "R"
 775                 "request\0"        Required_argument "r"
 776                 "script\0"         Required_argument "s"
 777                 "timeout\0"        Required_argument "T"
 778                 "version\0"        No_argument       "v"
 779                 "retries\0"        Required_argument "t"
 780                 "tryagain\0"       Required_argument "A"
 781                 "syslog\0"         No_argument       "S"
 782                 "request-option\0" Required_argument "O"
 783                 "no-default-options\0" No_argument   "o"
 784                 "foreground\0"     No_argument       "f"
 785                 "background\0"     No_argument       "b"
 786                 IF_FEATURE_UDHCPC_ARPING("arping\0"     No_argument       "a")
 787                 IF_FEATURE_UDHCP_PORT("client-port\0"   Required_argument "P")
 788                 ;
 789 #endif
 790         enum {
 791                 OPT_c = 1 << 0,
 792                 OPT_C = 1 << 1,
 793                 OPT_V = 1 << 2,
 794                 OPT_H = 1 << 3,
 795                 OPT_h = 1 << 4,
 796                 OPT_F = 1 << 5,
 797                 OPT_i = 1 << 6,
 798                 OPT_n = 1 << 7,
 799                 OPT_p = 1 << 8,
 800                 OPT_q = 1 << 9,
 801                 OPT_R = 1 << 10,
 802                 OPT_r = 1 << 11,
 803                 OPT_s = 1 << 12,
 804                 OPT_T = 1 << 13,
 805                 OPT_t = 1 << 14,
 806                 OPT_S = 1 << 15,
 807                 OPT_A = 1 << 16,
 808                 OPT_O = 1 << 17,
 809                 OPT_o = 1 << 18,
 810                 OPT_x = 1 << 19,
 811                 OPT_f = 1 << 20,
 812 /* The rest has variable bit positions, need to be clever */
 813                 OPTBIT_f = 20,
 814                 USE_FOR_MMU(             OPTBIT_b,)
 815                 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
 816                 IF_FEATURE_UDHCP_PORT(   OPTBIT_P,)
 817                 USE_FOR_MMU(             OPT_b = 1 << OPTBIT_b,)
 818                 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
 819                 IF_FEATURE_UDHCP_PORT(   OPT_P = 1 << OPTBIT_P,)
 820         };
 821
 822         /* Default options. */
 823         IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
 824         IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
 825         client_config.interface = "eth0";
 826         client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
 827         str_V = "udhcp "BB_VER;
 828
 829         /* Parse command line */
 830         /* Cc: mutually exclusive; O,x: list; -T,-t,-A take numeric param */
 831         opt_complementary = "c--C:C--c:O::x::T+:t+:A+"
 832 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 833                 ":vv"
 834 #endif
 835                 ;
 836         IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
 837         opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:f"
 838                 USE_FOR_MMU("b")
 839                 IF_FEATURE_UDHCPC_ARPING("a")
 840                 IF_FEATURE_UDHCP_PORT("P:")
 841                 "v"
 842                 , &str_c, &str_V, &str_h, &str_h, &str_F
 843                 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
 844                 , &client_config.script /* s */
 845                 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
 846                 , &list_O
 847                 , &list_x
 848                 IF_FEATURE_UDHCP_PORT(, &str_P)
 849 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 850                 , &dhcp_verbose
 851 #endif
 852                 );
 853         if (opt & (OPT_h|OPT_H))
 854                 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
 855         if (opt & OPT_F) {
 856                 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
 857                 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
 858                 /* Flag bits: 0000NEOS
 859                  * S: 1 = Client requests server to update A RR in DNS as well as PTR
 860                  * O: 1 = Server indicates to client that DNS has been updated regardless
 861                  * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
 862                  *    not "host.domain.com". Format 0 is obsolete.
 863                  * N: 1 = Client requests server to not update DNS (S must be 0 then)
 864                  * Two [0] bytes which follow are deprecated and must be 0.
 865                  */
 866                 client_config.fqdn[OPT_DATA + 0] = 0x1;
 867                 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
 868                 /*client_config.fqdn[OPT_DATA + 2] = 0; */
 869         }
 870         if (opt & OPT_r)
 871                 requested_ip = inet_addr(str_r);
 872 #if ENABLE_FEATURE_UDHCP_PORT
 873         if (opt & OPT_P) {
 874                 CLIENT_PORT = xatou16(str_P);
 875                 SERVER_PORT = CLIENT_PORT - 1;
 876         }
 877 #endif
 878         if (opt & OPT_o)
 879                 client_config.no_default_options = 1;
 880         while (list_O) {
 881                 char *optstr = llist_pop(&list_O);
 882                 int n = index_in_strings(dhcp_option_strings, optstr);
 883                 if (n < 0)
 884                         bb_error_msg_and_die("unknown option '%s'", optstr);
 885                 n = dhcp_options[n].code;
 886                 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
 887         }
 888         while (list_x) {
 889                 int n;
 890                 char *optstr = llist_pop(&list_x);
 891                 char *colon = strchr(optstr, ':');
 892                 if (colon)
 893                         *colon = '\0';
 894                 n = index_in_strings(dhcp_option_strings, optstr);
 895                 if (n < 0)
 896                         bb_error_msg_and_die("unknown option '%s'", optstr);
 897                 if (colon)
 898                         *colon = ' ';
 899                 udhcp_str2optset(optstr, &client_config.options);
 900         }
 901
 902         if (udhcp_read_interface(client_config.interface,
 903                         &client_config.ifindex,
 904                         NULL,
 905                         client_config.client_mac)
 906         ) {
 907                 return 1;
 908         }
 909
 910         if (opt & OPT_c) {
 911                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
 912         } else if (!(opt & OPT_C)) {
 913                 /* not set and not suppressed, set the default client ID */
 914                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
 915                 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
 916                 memcpy(client_config.clientid + OPT_DATA+1, client_config.client_mac, 6);
 917         }
 918         if (str_V[0] != '\0')
 919                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
 920 #if !BB_MMU
 921         /* on NOMMU reexec (i.e., background) early */
 922         if (!(opt & OPT_f)) {
 923                 bb_daemonize_or_rexec(0 /* flags */, argv);
 924                 logmode = LOGMODE_NONE;
 925         }
 926 #endif
 927         if (opt & OPT_S) {
 928                 openlog(applet_name, LOG_PID, LOG_DAEMON);
 929                 logmode |= LOGMODE_SYSLOG;
 930         }
 931
 932         /* Make sure fd 0,1,2 are open */
 933         bb_sanitize_stdio();
 934         /* Equivalent of doing a fflush after every \n */
 935         setlinebuf(stdout);
 936         /* Create pidfile */
 937         write_pidfile(client_config.pidfile);
 938         /* Goes to stdout (unless NOMMU) and possibly syslog */
 939         bb_info_msg("%s (v"BB_VER") started", applet_name);
 940         /* Set up the signal pipe */
 941         udhcp_sp_setup();
 942         /* We want random_xid to be random... */
 943         srand(monotonic_us());
 944
 945         state = INIT_SELECTING;
 946         udhcp_run_script(NULL, "deconfig");
 947         change_listen_mode(LISTEN_RAW);
 948         packet_num = 0;
 949         timeout = 0;
 950         already_waited_sec = 0;
 951
 952         /* Main event loop. select() waits on signal pipe and possibly
 953          * on sockfd.
 954          * "continue" statements in code below jump to the top of the loop.
 955          */
 956         for (;;) {
 957                 /* silence "uninitialized!" warning */
 958                 unsigned timestamp_before_wait = timestamp_before_wait;
 959
 960                 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
 961
 962                 /* Was opening raw or udp socket here
 963                  * if (listen_mode != LISTEN_NONE && sockfd < 0),
 964                  * but on fast network renew responses return faster
 965                  * than we open sockets. Thus this code is moved
 966                  * to change_listen_mode(). Thus we open listen socket
 967                  * BEFORE we send renew request (see "case BOUND:"). */
 968
 969                 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
 970
 971                 tv.tv_sec = timeout - already_waited_sec;
 972                 tv.tv_usec = 0;
 973                 retval = 0;
 974                 /* If we already timed out, fall through with retval = 0, else... */
 975                 if ((int)tv.tv_sec > 0) {
 976                         timestamp_before_wait = (unsigned)monotonic_sec();
 977                         log1("Waiting on select...");
 978                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 979                         if (retval < 0) {
 980                                 /* EINTR? A signal was caught, don't panic */
 981                                 if (errno == EINTR) {
 982                                         already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
 983                                         continue;
 984                                 }
 985                                 /* Else: an error occured, panic! */
 986                                 bb_perror_msg_and_die("select");
 987                         }
 988                 }
 989
 990                 /* If timeout dropped to zero, time to become active:
 991                  * resend discover/renew/whatever
 992                  */
 993                 if (retval == 0) {
 994                         /* We will restart the wait in any case */
 995                         already_waited_sec = 0;
 996
 997                         switch (state) {
 998                         case INIT_SELECTING:
 999                                 if (packet_num < discover_retries) {
1000                                         if (packet_num == 0)
1001                                                 xid = random_xid();
1002                                         /* broadcast */
1003                                         send_discover(xid, requested_ip);
1004                                         timeout = discover_timeout;
1005                                         packet_num++;
1006                                         continue;
1007                                 }
1008  leasefail:
1009                                 udhcp_run_script(NULL, "leasefail");
1010 #if BB_MMU /* -b is not supported on NOMMU */
1011                                 if (opt & OPT_b) { /* background if no lease */
1012                                         bb_info_msg("No lease, forking to background");
1013                                         client_background();
1014                                         /* do not background again! */
1015                                         opt = ((opt & ~OPT_b) | OPT_f);
1016                                 } else
1017 #endif
1018                                 if (opt & OPT_n) { /* abort if no lease */
1019                                         bb_info_msg("No lease, failing");
1020                                         retval = 1;
1021                                         goto ret;
1022                                 }
1023                                 /* wait before trying again */
1024                                 timeout = tryagain_timeout;
1025                                 packet_num = 0;
1026                                 continue;
1027                         case REQUESTING:
1028                                 if (packet_num < discover_retries) {
1029                                         /* send broadcast select packet */
1030                                         send_select(xid, server_addr, requested_ip);
1031                                         timeout = discover_timeout;
1032                                         packet_num++;
1033                                         continue;
1034                                 }
1035                                 /* Timed out, go back to init state.
1036                                  * "discover...select...discover..." loops
1037                                  * were seen in the wild. Treat them similarly
1038                                  * to "no response to discover" case */
1039                                 change_listen_mode(LISTEN_RAW);
1040                                 state = INIT_SELECTING;
1041                                 goto leasefail;
1042                         case BOUND:
1043                                 /* 1/2 lease passed, enter renewing state */
1044                                 state = RENEWING;
1045                                 change_listen_mode(LISTEN_KERNEL);
1046                                 log1("Entering renew state");
1047                                 /* fall right through */
1048                         case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1049                         case_RENEW_REQUESTED:
1050                         case RENEWING:
1051                                 if (timeout > 60) {
1052                                         /* send an unicast renew request */
1053                         /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1054                          * a new UDP socket for sending inside send_renew.
1055                          * I hazard to guess existing listening socket
1056                          * is somehow conflicting with it, but why is it
1057                          * not deterministic then?! Strange.
1058                          * Anyway, it does recover by eventually failing through
1059                          * into INIT_SELECTING state.
1060                          */
1061                                         send_renew(xid, server_addr, requested_ip);
1062                                         timeout >>= 1;
1063                                         continue;
1064                                 }
1065                                 /* Timed out, enter rebinding state */
1066                                 log1("Entering rebinding state");
1067                                 state = REBINDING;
1068                                 /* fall right through */
1069                         case REBINDING:
1070                                 /* Switch to bcast receive */
1071                                 change_listen_mode(LISTEN_RAW);
1072                                 /* Lease is *really* about to run out,
1073                                  * try to find DHCP server using broadcast */
1074                                 if (timeout > 0) {
1075                                         /* send a broadcast renew request */
1076                                         send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1077                                         timeout >>= 1;
1078                                         continue;
1079                                 }
1080                                 /* Timed out, enter init state */
1081                                 bb_info_msg("Lease lost, entering init state");
1082                                 udhcp_run_script(NULL, "deconfig");
1083                                 state = INIT_SELECTING;
1084                                 /*timeout = 0; - already is */
1085                                 packet_num = 0;
1086                                 continue;
1087                         /* case RELEASED: */
1088                         }
1089                         /* yah, I know, *you* say it would never happen */
1090                         timeout = INT_MAX;
1091                         continue; /* back to main loop */
1092                 } /* if select timed out */
1093
1094                 /* select() didn't timeout, something happened */
1095
1096                 /* Is it a signal? */
1097                 /* note: udhcp_sp_read checks FD_ISSET before reading */
1098                 switch (udhcp_sp_read(&rfds)) {
1099                 case SIGUSR1:
1100                         perform_renew();
1101                         if (state == RENEW_REQUESTED)
1102                                 goto case_RENEW_REQUESTED;
1103                         /* Start things over */
1104                         packet_num = 0;
1105                         /* Kill any timeouts, user wants this to hurry along */
1106                         timeout = 0;
1107                         continue;
1108                 case SIGUSR2:
1109                         perform_release(requested_ip, server_addr);
1110                         timeout = INT_MAX;
1111                         continue;
1112                 case SIGTERM:
1113                         bb_info_msg("Received SIGTERM");
1114                         if (opt & OPT_R) /* release on quit */
1115                                 perform_release(requested_ip, server_addr);
1116                         goto ret0;
1117                 }
1118
1119                 /* Is it a packet? */
1120                 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1121                         continue; /* no */
1122
1123                 {
1124                         int len;
1125
1126                         /* A packet is ready, read it */
1127                         if (listen_mode == LISTEN_KERNEL)
1128                                 len = udhcp_recv_kernel_packet(&packet, sockfd);
1129                         else
1130                                 len = udhcp_recv_raw_packet(&packet, sockfd);
1131                         if (len == -1) {
1132                                 /* Error is severe, reopen socket */
1133                                 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1134                                 sleep(discover_timeout); /* 3 seconds by default */
1135                                 change_listen_mode(listen_mode); /* just close and reopen */
1136                         }
1137                         /* If this packet will turn out to be unrelated/bogus,
1138                          * we will go back and wait for next one.
1139                          * Be sure timeout is properly decreased. */
1140                         already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1141                         if (len < 0)
1142                                 continue;
1143                 }
1144
1145                 if (packet.xid != xid) {
1146                         log1("xid %x (our is %x), ignoring packet",
1147                                 (unsigned)packet.xid, (unsigned)xid);
1148                         continue;
1149                 }
1150
1151                 /* Ignore packets that aren't for us */
1152                 if (packet.hlen != 6
1153                  || memcmp(packet.chaddr, client_config.client_mac, 6)
1154                 ) {
1155 //FIXME: need to also check that last 10 bytes are zero
1156                         log1("chaddr does not match, ignoring packet"); // log2?
1157                         continue;
1158                 }
1159
1160                 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1161                 if (message == NULL) {
1162                         bb_error_msg("no message type option, ignoring packet");
1163                         continue;
1164                 }
1165
1166                 switch (state) {
1167                 case INIT_SELECTING:
1168                         /* Must be a DHCPOFFER to one of our xid's */
1169                         if (*message == DHCPOFFER) {
1170                 /* TODO: why we don't just fetch server's IP from IP header? */
1171                                 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1172                                 if (!temp) {
1173                                         bb_error_msg("no server ID in message");
1174                                         continue;
1175                                         /* still selecting - this server looks bad */
1176                                 }
1177                                 /* it IS unaligned sometimes, don't "optimize" */
1178                                 move_from_unaligned32(server_addr, temp);
1179                                 xid = packet.xid;
1180                                 requested_ip = packet.yiaddr;
1181
1182                                 /* enter requesting state */
1183                                 state = REQUESTING;
1184                                 timeout = 0;
1185                                 packet_num = 0;
1186                                 already_waited_sec = 0;
1187                         }
1188                         continue;
1189                 case REQUESTING:
1190                 case RENEWING:
1191                 case RENEW_REQUESTED:
1192                 case REBINDING:
1193                         if (*message == DHCPACK) {
1194                                 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1195                                 if (!temp) {
1196                                         bb_error_msg("no lease time with ACK, using 1 hour lease");
1197                                         lease_seconds = 60 * 60;
1198                                 } else {
1199                                         /* it IS unaligned sometimes, don't "optimize" */
1200                                         move_from_unaligned32(lease_seconds, temp);
1201                                         lease_seconds = ntohl(lease_seconds);
1202                                         lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
1203                                         if (lease_seconds < 10) /* and not too small */
1204                                                 lease_seconds = 10;
1205                                 }
1206 #if ENABLE_FEATURE_UDHCPC_ARPING
1207                                 if (opt & OPT_a) {
1208 /* RFC 2131 3.1 paragraph 5:
1209  * "The client receives the DHCPACK message with configuration
1210  * parameters. The client SHOULD perform a final check on the
1211  * parameters (e.g., ARP for allocated network address), and notes
1212  * the duration of the lease specified in the DHCPACK message. At this
1213  * point, the client is configured. If the client detects that the
1214  * address is already in use (e.g., through the use of ARP),
1215  * the client MUST send a DHCPDECLINE message to the server and restarts
1216  * the configuration process..." */
1217                                         if (!arpping(packet.yiaddr,
1218                                                         NULL,
1219                                                         (uint32_t) 0,
1220                                                         client_config.client_mac,
1221                                                         client_config.interface)
1222                                         ) {
1223                                                 bb_info_msg("Offered address is in use "
1224                                                         "(got ARP reply), declining");
1225                                                 send_decline(xid, server_addr, packet.yiaddr);
1226
1227                                                 if (state != REQUESTING)
1228                                                         udhcp_run_script(NULL, "deconfig");
1229                                                 change_listen_mode(LISTEN_RAW);
1230                                                 state = INIT_SELECTING;
1231                                                 requested_ip = 0;
1232                                                 timeout = tryagain_timeout;
1233                                                 packet_num = 0;
1234                                                 already_waited_sec = 0;
1235                                                 continue; /* back to main loop */
1236                                         }
1237                                 }
1238 #endif
1239                                 /* enter bound state */
1240                                 timeout = lease_seconds / 2;
1241                                 {
1242                                         struct in_addr temp_addr;
1243                                         temp_addr.s_addr = packet.yiaddr;
1244                                         bb_info_msg("Lease of %s obtained, lease time %u",
1245                                                 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1246                                 }
1247                                 requested_ip = packet.yiaddr;
1248                                 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1249
1250                                 state = BOUND;
1251                                 change_listen_mode(LISTEN_NONE);
1252                                 if (opt & OPT_q) { /* quit after lease */
1253                                         if (opt & OPT_R) /* release on quit */
1254                                                 perform_release(requested_ip, server_addr);
1255                                         goto ret0;
1256                                 }
1257                                 /* future renew failures should not exit (JM) */
1258                                 opt &= ~OPT_n;
1259 #if BB_MMU /* NOMMU case backgrounded earlier */
1260                                 if (!(opt & OPT_f)) {
1261                                         client_background();
1262                                         /* do not background again! */
1263                                         opt = ((opt & ~OPT_b) | OPT_f);
1264                                 }
1265 #endif
1266                                 already_waited_sec = 0;
1267                                 continue; /* back to main loop */
1268                         }
1269                         if (*message == DHCPNAK) {
1270                                 /* return to init state */
1271                                 bb_info_msg("Received DHCP NAK");
1272                                 udhcp_run_script(&packet, "nak");
1273                                 if (state != REQUESTING)
1274                                         udhcp_run_script(NULL, "deconfig");
1275                                 change_listen_mode(LISTEN_RAW);
1276                                 sleep(3); /* avoid excessive network traffic */
1277                                 state = INIT_SELECTING;
1278                                 requested_ip = 0;
1279                                 timeout = 0;
1280                                 packet_num = 0;
1281                                 already_waited_sec = 0;
1282                         }
1283                         continue;
1284                 /* case BOUND: - ignore all packets */
1285                 /* case RELEASED: - ignore all packets */
1286                 }
1287                 /* back to main loop */
1288         } /* for (;;) - main loop ends */
1289
1290  ret0:
1291         retval = 0;
1292  ret:
1293         /*if (client_config.pidfile) - remove_pidfile has its own check */
1294                 remove_pidfile(client_config.pidfile);
1295         return retval;
1296 }