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