networking/udhcp/dhcpc.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * udhcp 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 <netinet/if_ether.h>
  29 #include <netpacket/packet.h>
  30 #include <linux/filter.h>
  31
  32 /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
  33
  34
  35 #if ENABLE_LONG_OPTS
  36 static const char udhcpc_longopts[] ALIGN1 =
  37         "clientid-none\0"  No_argument       "C"
  38         "vendorclass\0"    Required_argument "V"
  39         "hostname\0"       Required_argument "H"
  40         "fqdn\0"           Required_argument "F"
  41         "interface\0"      Required_argument "i"
  42         "now\0"            No_argument       "n"
  43         "pidfile\0"        Required_argument "p"
  44         "quit\0"           No_argument       "q"
  45         "release\0"        No_argument       "R"
  46         "request\0"        Required_argument "r"
  47         "script\0"         Required_argument "s"
  48         "timeout\0"        Required_argument "T"
  49         "retries\0"        Required_argument "t"
  50         "tryagain\0"       Required_argument "A"
  51         "syslog\0"         No_argument       "S"
  52         "request-option\0" Required_argument "O"
  53         "no-default-options\0" No_argument   "o"
  54         "foreground\0"     No_argument       "f"
  55         "background\0"     No_argument       "b"
  56         "broadcast\0"      No_argument       "B"
  57         IF_FEATURE_UDHCPC_ARPING("arping\0"     No_argument       "a")
  58         IF_FEATURE_UDHCP_PORT("client-port\0"   Required_argument "P")
  59         ;
  60 #endif
  61 /* Must match getopt32 option string order */
  62 enum {
  63         OPT_C = 1 << 0,
  64         OPT_V = 1 << 1,
  65         OPT_H = 1 << 2,
  66         OPT_h = 1 << 3,
  67         OPT_F = 1 << 4,
  68         OPT_i = 1 << 5,
  69         OPT_n = 1 << 6,
  70         OPT_p = 1 << 7,
  71         OPT_q = 1 << 8,
  72         OPT_R = 1 << 9,
  73         OPT_r = 1 << 10,
  74         OPT_s = 1 << 11,
  75         OPT_T = 1 << 12,
  76         OPT_t = 1 << 13,
  77         OPT_S = 1 << 14,
  78         OPT_A = 1 << 15,
  79         OPT_O = 1 << 16,
  80         OPT_o = 1 << 17,
  81         OPT_x = 1 << 18,
  82         OPT_f = 1 << 19,
  83         OPT_B = 1 << 20,
  84 /* The rest has variable bit positions, need to be clever */
  85         OPTBIT_B = 20,
  86         USE_FOR_MMU(             OPTBIT_b,)
  87         IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
  88         IF_FEATURE_UDHCP_PORT(   OPTBIT_P,)
  89         USE_FOR_MMU(             OPT_b = 1 << OPTBIT_b,)
  90         IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
  91         IF_FEATURE_UDHCP_PORT(   OPT_P = 1 << OPTBIT_P,)
  92 };
  93
  94
  95 /*** Script execution code ***/
  96
  97 /* get a rough idea of how long an option will be (rounding up...) */
  98 static const uint8_t len_of_option_as_string[] = {
  99         [OPTION_IP              ] = sizeof("255.255.255.255 "),
 100         [OPTION_IP_PAIR         ] = sizeof("255.255.255.255 ") * 2,
 101         [OPTION_STATIC_ROUTES   ] = sizeof("255.255.255.255/32 255.255.255.255 "),
 102         [OPTION_6RD             ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
 103         [OPTION_STRING          ] = 1,
 104 #if ENABLE_FEATURE_UDHCP_RFC3397
 105         [OPTION_DNS_STRING      ] = 1, /* unused */
 106         /* Hmmm, this severely overestimates size if SIP_SERVERS option
 107          * is in domain name form: N-byte option in binary form
 108          * mallocs ~16*N bytes. But it is freed almost at once.
 109          */
 110         [OPTION_SIP_SERVERS     ] = sizeof("255.255.255.255 "),
 111 #endif
 112 //      [OPTION_BOOLEAN         ] = sizeof("yes "),
 113         [OPTION_U8              ] = sizeof("255 "),
 114         [OPTION_U16             ] = sizeof("65535 "),
 115 //      [OPTION_S16             ] = sizeof("-32768 "),
 116         [OPTION_U32             ] = sizeof("4294967295 "),
 117         [OPTION_S32             ] = sizeof("-2147483684 "),
 118 };
 119
 120 /* note: ip is a pointer to an IP in network order, possibly misaliged */
 121 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
 122 {
 123         return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
 124 }
 125
 126 /* really simple implementation, just count the bits */
 127 static int mton(uint32_t mask)
 128 {
 129         int i = 0;
 130         mask = ntohl(mask); /* 111110000-like bit pattern */
 131         while (mask) {
 132                 i++;
 133                 mask <<= 1;
 134         }
 135         return i;
 136 }
 137
 138 /* Check if a given label represents a valid DNS label
 139  * Return pointer to the first character after the label upon success,
 140  * NULL otherwise.
 141  * See RFC1035, 2.3.1
 142  */
 143 /* We don't need to be particularly anal. For example, allowing _, hyphen
 144  * at the end, or leading and trailing dots would be ok, since it
 145  * can't be used for attacks. (Leading hyphen can be, if someone uses
 146  * cmd "$hostname"
 147  * in the script: then hostname may be treated as an option)
 148  */
 149 static const char *valid_domain_label(const char *label)
 150 {
 151         unsigned char ch;
 152         unsigned pos = 0;
 153
 154         for (;;) {
 155                 ch = *label;
 156                 if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
 157                         if (pos == 0) {
 158                                 /* label must begin with letter */
 159                                 return NULL;
 160                         }
 161                         if (ch < '0' || ch > '9') {
 162                                 if (ch == '\0' || ch == '.')
 163                                         return label;
 164                                 /* DNS allows only '-', but we are more permissive */
 165                                 if (ch != '-' && ch != '_')
 166                                         return NULL;
 167                         }
 168                 }
 169                 label++;
 170                 pos++;
 171                 //Do we want this?
 172                 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
 173                 //      return NULL;
 174         }
 175 }
 176
 177 /* Check if a given name represents a valid DNS name */
 178 /* See RFC1035, 2.3.1 */
 179 static int good_hostname(const char *name)
 180 {
 181         //const char *start = name;
 182
 183         for (;;) {
 184                 name = valid_domain_label(name);
 185                 if (!name)
 186                         return 0;
 187                 if (!name[0])
 188                         return 1;
 189                         //Do we want this?
 190                         //return ((name - start) < 1025); /* NS_MAXDNAME */
 191                 name++;
 192         }
 193 }
 194
 195 /* Create "opt_name=opt_value" string */
 196 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
 197 {
 198         unsigned upper_length;
 199         int len, type, optlen;
 200         char *dest, *ret;
 201
 202         /* option points to OPT_DATA, need to go back to get OPT_LEN */
 203         len = option[-OPT_DATA + OPT_LEN];
 204
 205         type = optflag->flags & OPTION_TYPE_MASK;
 206         optlen = dhcp_option_lengths[type];
 207         upper_length = len_of_option_as_string[type]
 208                 * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
 209
 210         dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
 211         dest += sprintf(ret, "%s=", opt_name);
 212
 213         while (len >= optlen) {
 214                 switch (type) {
 215                 case OPTION_IP:
 216                 case OPTION_IP_PAIR:
 217                         dest += sprint_nip(dest, "", option);
 218                         if (type == OPTION_IP)
 219                                 break;
 220                         dest += sprint_nip(dest, "/", option + 4);
 221                         break;
 222 //              case OPTION_BOOLEAN:
 223 //                      dest += sprintf(dest, *option ? "yes" : "no");
 224 //                      break;
 225                 case OPTION_U8:
 226                         dest += sprintf(dest, "%u", *option);
 227                         break;
 228 //              case OPTION_S16:
 229                 case OPTION_U16: {
 230                         uint16_t val_u16;
 231                         move_from_unaligned16(val_u16, option);
 232                         dest += sprintf(dest, "%u", ntohs(val_u16));
 233                         break;
 234                 }
 235                 case OPTION_S32:
 236                 case OPTION_U32: {
 237                         uint32_t val_u32;
 238                         move_from_unaligned32(val_u32, option);
 239                         dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
 240                         break;
 241                 }
 242                 /* Note: options which use 'return' instead of 'break'
 243                  * (for example, OPTION_STRING) skip the code which handles
 244                  * the case of list of options.
 245                  */
 246                 case OPTION_STRING:
 247                 case OPTION_STRING_HOST:
 248                         memcpy(dest, option, len);
 249                         dest[len] = '\0';
 250                         if (type == OPTION_STRING_HOST && !good_hostname(dest))
 251                                 safe_strncpy(dest, "bad", len);
 252                         return ret;
 253                 case OPTION_STATIC_ROUTES: {
 254                         /* Option binary format:
 255                          * mask [one byte, 0..32]
 256                          * ip [big endian, 0..4 bytes depending on mask]
 257                          * router [big endian, 4 bytes]
 258                          * may be repeated
 259                          *
 260                          * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
 261                          */
 262                         const char *pfx = "";
 263
 264                         while (len >= 1 + 4) { /* mask + 0-byte ip + router */
 265                                 uint32_t nip;
 266                                 uint8_t *p;
 267                                 unsigned mask;
 268                                 int bytes;
 269
 270                                 mask = *option++;
 271                                 if (mask > 32)
 272                                         break;
 273                                 len--;
 274
 275                                 nip = 0;
 276                                 p = (void*) &nip;
 277                                 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
 278                                 while (--bytes >= 0) {
 279                                         *p++ = *option++;
 280                                         len--;
 281                                 }
 282                                 if (len < 4)
 283                                         break;
 284
 285                                 /* print ip/mask */
 286                                 dest += sprint_nip(dest, pfx, (void*) &nip);
 287                                 pfx = " ";
 288                                 dest += sprintf(dest, "/%u ", mask);
 289                                 /* print router */
 290                                 dest += sprint_nip(dest, "", option);
 291                                 option += 4;
 292                                 len -= 4;
 293                         }
 294
 295                         return ret;
 296                 }
 297                 case OPTION_6RD:
 298                         /* Option binary format (see RFC 5969):
 299                          *  0                   1                   2                   3
 300                          *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 301                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 302                          * |  OPTION_6RD   | option-length |  IPv4MaskLen  |  6rdPrefixLen |
 303                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 304                          * |                           6rdPrefix                           |
 305                          * ...                        (16 octets)                        ...
 306                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 307                          * ...                   6rdBRIPv4Address(es)                    ...
 308                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 309                          * We convert it to a string
 310                          * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
 311                          *
 312                          * Sanity check: ensure that our length is at least 22 bytes, that
 313                          * IPv4MaskLen <= 32,
 314                          * 6rdPrefixLen <= 128,
 315                          * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
 316                          * (2nd condition need no check - it follows from 1st and 3rd).
 317                          * Else, return envvar with empty value ("optname=")
 318                          */
 319                         if (len >= (1 + 1 + 16 + 4)
 320                          && option[0] <= 32
 321                          && (option[1] + 32 - option[0]) <= 128
 322                         ) {
 323                                 /* IPv4MaskLen */
 324                                 dest += sprintf(dest, "%u ", *option++);
 325                                 /* 6rdPrefixLen */
 326                                 dest += sprintf(dest, "%u ", *option++);
 327                                 /* 6rdPrefix */
 328                                 dest += sprint_nip6(dest, /* "", */ option);
 329                                 option += 16;
 330                                 len -= 1 + 1 + 16 + 4;
 331                                 /* "+ 4" above corresponds to the length of IPv4 addr
 332                                  * we consume in the loop below */
 333                                 while (1) {
 334                                         /* 6rdBRIPv4Address(es) */
 335                                         dest += sprint_nip(dest, " ", option);
 336                                         option += 4;
 337                                         len -= 4; /* do we have yet another 4+ bytes? */
 338                                         if (len < 0)
 339                                                 break; /* no */
 340                                 }
 341                         }
 342
 343                         return ret;
 344 #if ENABLE_FEATURE_UDHCP_RFC3397
 345                 case OPTION_DNS_STRING:
 346                         /* unpack option into dest; use ret for prefix (i.e., "optname=") */
 347                         dest = dname_dec(option, len, ret);
 348                         if (dest) {
 349                                 free(ret);
 350                                 return dest;
 351                         }
 352                         /* error. return "optname=" string */
 353                         return ret;
 354                 case OPTION_SIP_SERVERS:
 355                         /* Option binary format:
 356                          * type: byte
 357                          * type=0: domain names, dns-compressed
 358                          * type=1: IP addrs
 359                          */
 360                         option++;
 361                         len--;
 362                         if (option[-1] == 0) {
 363                                 dest = dname_dec(option, len, ret);
 364                                 if (dest) {
 365                                         free(ret);
 366                                         return dest;
 367                                 }
 368                         } else
 369                         if (option[-1] == 1) {
 370                                 const char *pfx = "";
 371                                 while (1) {
 372                                         len -= 4;
 373                                         if (len < 0)
 374                                                 break;
 375                                         dest += sprint_nip(dest, pfx, option);
 376                                         pfx = " ";
 377                                         option += 4;
 378                                 }
 379                         }
 380                         return ret;
 381 #endif
 382                 } /* switch */
 383
 384                 /* If we are here, try to format any remaining data
 385                  * in the option as another, similarly-formatted option
 386                  */
 387                 option += optlen;
 388                 len -= optlen;
 389 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
 390 // Should we bail out/warn if we see multi-ip option which is
 391 // not allowed to be such (for example, DHCP_BROADCAST)? -
 392                 if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
 393                         break;
 394                 *dest++ = ' ';
 395                 *dest = '\0';
 396         } /* while */
 397
 398         return ret;
 399 }
 400
 401 /* put all the parameters into the environment */
 402 static char **fill_envp(struct dhcp_packet *packet)
 403 {
 404         int envc;
 405         int i;
 406         char **envp, **curr;
 407         const char *opt_name;
 408         uint8_t *temp;
 409         uint8_t overload = 0;
 410
 411 #define BITMAP unsigned
 412 #define BBITS (sizeof(BITMAP) * 8)
 413 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
 414 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
 415         BITMAP found_opts[256 / BBITS];
 416
 417         memset(found_opts, 0, sizeof(found_opts));
 418
 419         /* We need 6 elements for:
 420          * "interface=IFACE"
 421          * "ip=N.N.N.N" from packet->yiaddr
 422          * "siaddr=IP" from packet->siaddr_nip (unless 0)
 423          * "boot_file=FILE" from packet->file (unless overloaded)
 424          * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
 425          * terminating NULL
 426          */
 427         envc = 6;
 428         /* +1 element for each option, +2 for subnet option: */
 429         if (packet) {
 430                 /* note: do not search for "pad" (0) and "end" (255) options */
 431 //TODO: change logic to scan packet _once_
 432                 for (i = 1; i < 255; i++) {
 433                         temp = udhcp_get_option(packet, i);
 434                         if (temp) {
 435                                 if (i == DHCP_OPTION_OVERLOAD)
 436                                         overload = *temp;
 437                                 else if (i == DHCP_SUBNET)
 438                                         envc++; /* for $mask */
 439                                 envc++;
 440                                 /*if (i != DHCP_MESSAGE_TYPE)*/
 441                                 FOUND_OPTS(i) |= BMASK(i);
 442                         }
 443                 }
 444         }
 445         curr = envp = xzalloc(sizeof(envp[0]) * envc);
 446
 447         *curr = xasprintf("interface=%s", client_config.interface);
 448         putenv(*curr++);
 449
 450         if (!packet)
 451                 return envp;
 452
 453         /* Export BOOTP fields. Fields we don't (yet?) export:
 454          * uint8_t op;      // always BOOTREPLY
 455          * uint8_t htype;   // hardware address type. 1 = 10mb ethernet
 456          * uint8_t hlen;    // hardware address length
 457          * uint8_t hops;    // used by relay agents only
 458          * uint32_t xid;
 459          * uint16_t secs;   // elapsed since client began acquisition/renewal
 460          * uint16_t flags;  // only one flag so far: bcast. Never set by server
 461          * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
 462          *                  // if during renew server wants to give us differn IP?)
 463          * uint32_t gateway_nip; // relay agent IP address
 464          * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
 465          * TODO: export gateway_nip as $giaddr?
 466          */
 467         /* Most important one: yiaddr as $ip */
 468         *curr = xmalloc(sizeof("ip=255.255.255.255"));
 469         sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
 470         putenv(*curr++);
 471         if (packet->siaddr_nip) {
 472                 /* IP address of next server to use in bootstrap */
 473                 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
 474                 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
 475                 putenv(*curr++);
 476         }
 477         if (!(overload & FILE_FIELD) && packet->file[0]) {
 478                 /* watch out for invalid packets */
 479                 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
 480                 putenv(*curr++);
 481         }
 482         if (!(overload & SNAME_FIELD) && packet->sname[0]) {
 483                 /* watch out for invalid packets */
 484                 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
 485                 putenv(*curr++);
 486         }
 487
 488         /* Export known DHCP options */
 489         opt_name = dhcp_option_strings;
 490         i = 0;
 491         while (*opt_name) {
 492                 uint8_t code = dhcp_optflags[i].code;
 493                 BITMAP *found_ptr = &FOUND_OPTS(code);
 494                 BITMAP found_mask = BMASK(code);
 495                 if (!(*found_ptr & found_mask))
 496                         goto next;
 497                 *found_ptr &= ~found_mask; /* leave only unknown options */
 498                 temp = udhcp_get_option(packet, code);
 499                 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
 500                 putenv(*curr++);
 501                 if (code == DHCP_SUBNET) {
 502                         /* Subnet option: make things like "$ip/$mask" possible */
 503                         uint32_t subnet;
 504                         move_from_unaligned32(subnet, temp);
 505                         *curr = xasprintf("mask=%u", mton(subnet));
 506                         putenv(*curr++);
 507                 }
 508  next:
 509                 opt_name += strlen(opt_name) + 1;
 510                 i++;
 511         }
 512         /* Export unknown options */
 513         for (i = 0; i < 256;) {
 514                 BITMAP bitmap = FOUND_OPTS(i);
 515                 if (!bitmap) {
 516                         i += BBITS;
 517                         continue;
 518                 }
 519                 if (bitmap & BMASK(i)) {
 520                         unsigned len, ofs;
 521
 522                         temp = udhcp_get_option(packet, i);
 523                         /* udhcp_get_option returns ptr to data portion,
 524                          * need to go back to get len
 525                          */
 526                         len = temp[-OPT_DATA + OPT_LEN];
 527                         *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
 528                         ofs = sprintf(*curr, "opt%u=", i);
 529                         *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
 530                         putenv(*curr++);
 531                 }
 532                 i++;
 533         }
 534
 535         return envp;
 536 }
 537
 538 /* Call a script with a par file and env vars */
 539 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
 540 {
 541         char **envp, **curr;
 542         char *argv[3];
 543
 544         envp = fill_envp(packet);
 545
 546         /* call script */
 547         log1("Executing %s %s", client_config.script, name);
 548         argv[0] = (char*) client_config.script;
 549         argv[1] = (char*) name;
 550         argv[2] = NULL;
 551         spawn_and_wait(argv);
 552
 553         for (curr = envp; *curr; curr++) {
 554                 log2(" %s", *curr);
 555                 bb_unsetenv_and_free(*curr);
 556         }
 557         free(envp);
 558 }
 559
 560
 561 /*** Sending/receiving packets ***/
 562
 563 static ALWAYS_INLINE uint32_t random_xid(void)
 564 {
 565         return rand();
 566 }
 567
 568 /* Initialize the packet with the proper defaults */
 569 static void init_packet(struct dhcp_packet *packet, char type)
 570 {
 571         uint16_t secs;
 572
 573         /* Fill in: op, htype, hlen, cookie fields; message type option: */
 574         udhcp_init_header(packet, type);
 575
 576         packet->xid = random_xid();
 577
 578         client_config.last_secs = monotonic_sec();
 579         if (client_config.first_secs == 0)
 580                 client_config.first_secs = client_config.last_secs;
 581         secs = client_config.last_secs - client_config.first_secs;
 582         packet->secs = htons(secs);
 583
 584         memcpy(packet->chaddr, client_config.client_mac, 6);
 585         if (client_config.clientid)
 586                 udhcp_add_binary_option(packet, client_config.clientid);
 587 }
 588
 589 static void add_client_options(struct dhcp_packet *packet)
 590 {
 591         uint8_t c;
 592         int i, end, len;
 593
 594         udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
 595
 596         /* Add a "param req" option with the list of options we'd like to have
 597          * from stubborn DHCP servers. Pull the data from the struct in common.c.
 598          * No bounds checking because it goes towards the head of the packet. */
 599         end = udhcp_end_option(packet->options);
 600         len = 0;
 601         for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
 602                 if ((   (dhcp_optflags[i].flags & OPTION_REQ)
 603                      && !client_config.no_default_options
 604                     )
 605                  || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
 606                 ) {
 607                         packet->options[end + OPT_DATA + len] = c;
 608                         len++;
 609                 }
 610         }
 611         if (len) {
 612                 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
 613                 packet->options[end + OPT_LEN] = len;
 614                 packet->options[end + OPT_DATA + len] = DHCP_END;
 615         }
 616
 617         if (client_config.vendorclass)
 618                 udhcp_add_binary_option(packet, client_config.vendorclass);
 619         if (client_config.hostname)
 620                 udhcp_add_binary_option(packet, client_config.hostname);
 621         if (client_config.fqdn)
 622                 udhcp_add_binary_option(packet, client_config.fqdn);
 623
 624         /* Request broadcast replies if we have no IP addr */
 625         if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
 626                 packet->flags |= htons(BROADCAST_FLAG);
 627
 628         /* Add -x options if any */
 629         {
 630                 struct option_set *curr = client_config.options;
 631                 while (curr) {
 632                         udhcp_add_binary_option(packet, curr->data);
 633                         curr = curr->next;
 634                 }
 635 //              if (client_config.sname)
 636 //                      strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
 637 //              if (client_config.boot_file)
 638 //                      strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
 639         }
 640
 641         // This will be needed if we remove -V VENDOR_STR in favor of
 642         // -x vendor:VENDOR_STR
 643         //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
 644         //      /* not set, set the default vendor ID */
 645         //      ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
 646 }
 647
 648 /* RFC 2131
 649  * 4.4.4 Use of broadcast and unicast
 650  *
 651  * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
 652  * messages, unless the client knows the address of a DHCP server.
 653  * The client unicasts DHCPRELEASE messages to the server. Because
 654  * the client is declining the use of the IP address supplied by the server,
 655  * the client broadcasts DHCPDECLINE messages.
 656  *
 657  * When the DHCP client knows the address of a DHCP server, in either
 658  * INIT or REBOOTING state, the client may use that address
 659  * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
 660  * The client may also use unicast to send DHCPINFORM messages
 661  * to a known DHCP server. If the client receives no response to DHCP
 662  * messages sent to the IP address of a known DHCP server, the DHCP
 663  * client reverts to using the IP broadcast address.
 664  */
 665
 666 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
 667 {
 668         return udhcp_send_raw_packet(packet,
 669                 /*src*/ INADDR_ANY, CLIENT_PORT,
 670                 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
 671                 client_config.ifindex);
 672 }
 673
 674 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
 675 /* NOINLINE: limit stack usage in caller */
 676 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
 677 {
 678         struct dhcp_packet packet;
 679
 680         /* Fill in: op, htype, hlen, cookie, chaddr fields,
 681          * random xid field (we override it below),
 682          * client-id option (unless -C), message type option:
 683          */
 684         init_packet(&packet, DHCPDISCOVER);
 685
 686         packet.xid = xid;
 687         if (requested)
 688                 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 689
 690         /* Add options: maxsize,
 691          * optionally: hostname, fqdn, vendorclass,
 692          * "param req" option according to -O, options specified with -x
 693          */
 694         add_client_options(&packet);
 695
 696         bb_info_msg("Sending discover...");
 697         return raw_bcast_from_client_config_ifindex(&packet);
 698 }
 699
 700 /* Broadcast a DHCP request message */
 701 /* RFC 2131 3.1 paragraph 3:
 702  * "The client _broadcasts_ a DHCPREQUEST message..."
 703  */
 704 /* NOINLINE: limit stack usage in caller */
 705 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
 706 {
 707         struct dhcp_packet packet;
 708         struct in_addr addr;
 709
 710 /*
 711  * RFC 2131 4.3.2 DHCPREQUEST message
 712  * ...
 713  * If the DHCPREQUEST message contains a 'server identifier'
 714  * option, the message is in response to a DHCPOFFER message.
 715  * Otherwise, the message is a request to verify or extend an
 716  * existing lease. If the client uses a 'client identifier'
 717  * in a DHCPREQUEST message, it MUST use that same 'client identifier'
 718  * in all subsequent messages. If the client included a list
 719  * of requested parameters in a DHCPDISCOVER message, it MUST
 720  * include that list in all subsequent messages.
 721  */
 722         /* Fill in: op, htype, hlen, cookie, chaddr fields,
 723          * random xid field (we override it below),
 724          * client-id option (unless -C), message type option:
 725          */
 726         init_packet(&packet, DHCPREQUEST);
 727
 728         packet.xid = xid;
 729         udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 730
 731         udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 732
 733         /* Add options: maxsize,
 734          * optionally: hostname, fqdn, vendorclass,
 735          * "param req" option according to -O, and options specified with -x
 736          */
 737         add_client_options(&packet);
 738
 739         addr.s_addr = requested;
 740         bb_info_msg("Sending select for %s...", inet_ntoa(addr));
 741         return raw_bcast_from_client_config_ifindex(&packet);
 742 }
 743
 744 /* Unicast or broadcast a DHCP renew message */
 745 /* NOINLINE: limit stack usage in caller */
 746 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
 747 {
 748         struct dhcp_packet packet;
 749
 750 /*
 751  * RFC 2131 4.3.2 DHCPREQUEST message
 752  * ...
 753  * DHCPREQUEST generated during RENEWING state:
 754  *
 755  * 'server identifier' MUST NOT be filled in, 'requested IP address'
 756  * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
 757  * client's IP address. In this situation, the client is completely
 758  * configured, and is trying to extend its lease. This message will
 759  * be unicast, so no relay agents will be involved in its
 760  * transmission.  Because 'giaddr' is therefore not filled in, the
 761  * DHCP server will trust the value in 'ciaddr', and use it when
 762  * replying to the client.
 763  */
 764         /* Fill in: op, htype, hlen, cookie, chaddr fields,
 765          * random xid field (we override it below),
 766          * client-id option (unless -C), message type option:
 767          */
 768         init_packet(&packet, DHCPREQUEST);
 769
 770         packet.xid = xid;
 771         packet.ciaddr = ciaddr;
 772
 773         /* Add options: maxsize,
 774          * optionally: hostname, fqdn, vendorclass,
 775          * "param req" option according to -O, and options specified with -x
 776          */
 777         add_client_options(&packet);
 778
 779         bb_info_msg("Sending renew...");
 780         if (server)
 781                 return udhcp_send_kernel_packet(&packet,
 782                         ciaddr, CLIENT_PORT,
 783                         server, SERVER_PORT);
 784         return raw_bcast_from_client_config_ifindex(&packet);
 785 }
 786
 787 #if ENABLE_FEATURE_UDHCPC_ARPING
 788 /* Broadcast a DHCP decline message */
 789 /* NOINLINE: limit stack usage in caller */
 790 static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
 791 {
 792         struct dhcp_packet packet;
 793
 794         /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
 795          * client-id option (unless -C), message type option:
 796          */
 797         init_packet(&packet, DHCPDECLINE);
 798
 799 #if 0
 800         /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
 801          * but in case the server is buggy and wants DHCPDECLINE's xid
 802          * to match the xid which started entire handshake,
 803          * we use the same xid we used in initial DHCPDISCOVER:
 804          */
 805         packet.xid = xid;
 806 #endif
 807         /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
 808         udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 809
 810         udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 811
 812         bb_info_msg("Sending decline...");
 813         return raw_bcast_from_client_config_ifindex(&packet);
 814 }
 815 #endif
 816
 817 /* Unicast a DHCP release message */
 818 static int send_release(uint32_t server, uint32_t ciaddr)
 819 {
 820         struct dhcp_packet packet;
 821
 822         /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
 823          * client-id option (unless -C), message type option:
 824          */
 825         init_packet(&packet, DHCPRELEASE);
 826
 827         /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
 828         packet.ciaddr = ciaddr;
 829
 830         udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 831
 832         bb_info_msg("Sending release...");
 833         return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
 834 }
 835
 836 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
 837 /* NOINLINE: limit stack usage in caller */
 838 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
 839 {
 840         int bytes;
 841         struct ip_udp_dhcp_packet packet;
 842         uint16_t check;
 843
 844         bytes = safe_read(fd, &packet, sizeof(packet));
 845         if (bytes < 0) {
 846                 log1("Packet read error, ignoring");
 847                 /* NB: possible down interface, etc. Caller should pause. */
 848                 return bytes; /* returns -1 */
 849         }
 850
 851         if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
 852                 log1("Packet is too short, ignoring");
 853                 return -2;
 854         }
 855
 856         if (bytes < ntohs(packet.ip.tot_len)) {
 857                 /* packet is bigger than sizeof(packet), we did partial read */
 858                 log1("Oversized packet, ignoring");
 859                 return -2;
 860         }
 861
 862         /* ignore any extra garbage bytes */
 863         bytes = ntohs(packet.ip.tot_len);
 864
 865         /* make sure its the right packet for us, and that it passes sanity checks */
 866         if (packet.ip.protocol != IPPROTO_UDP
 867          || packet.ip.version != IPVERSION
 868          || packet.ip.ihl != (sizeof(packet.ip) >> 2)
 869          || packet.udp.dest != htons(CLIENT_PORT)
 870         /* || bytes > (int) sizeof(packet) - can't happen */
 871          || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
 872         ) {
 873                 log1("Unrelated/bogus packet, ignoring");
 874                 return -2;
 875         }
 876
 877         /* verify IP checksum */
 878         check = packet.ip.check;
 879         packet.ip.check = 0;
 880         if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
 881                 log1("Bad IP header checksum, ignoring");
 882                 return -2;
 883         }
 884
 885         /* verify UDP checksum. IP header has to be modified for this */
 886         memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
 887         /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
 888         packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
 889         check = packet.udp.check;
 890         packet.udp.check = 0;
 891         if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
 892                 log1("Packet with bad UDP checksum received, ignoring");
 893                 return -2;
 894         }
 895
 896         if (packet.data.cookie != htonl(DHCP_MAGIC)) {
 897                 bb_info_msg("Packet with bad magic, ignoring");
 898                 return -2;
 899         }
 900
 901         log1("Received a packet");
 902         udhcp_dump_packet(&packet.data);
 903
 904         bytes -= sizeof(packet.ip) + sizeof(packet.udp);
 905         memcpy(dhcp_pkt, &packet.data, bytes);
 906         return bytes;
 907 }
 908
 909
 910 /*** Main ***/
 911
 912 static int sockfd = -1;
 913
 914 #define LISTEN_NONE   0
 915 #define LISTEN_KERNEL 1
 916 #define LISTEN_RAW    2
 917 static smallint listen_mode;
 918
 919 /* initial state: (re)start DHCP negotiation */
 920 #define INIT_SELECTING  0
 921 /* discover was sent, DHCPOFFER reply received */
 922 #define REQUESTING      1
 923 /* select/renew was sent, DHCPACK reply received */
 924 #define BOUND           2
 925 /* half of lease passed, want to renew it by sending unicast renew requests */
 926 #define RENEWING        3
 927 /* renew requests were not answered, lease is almost over, send broadcast renew */
 928 #define REBINDING       4
 929 /* manually requested renew (SIGUSR1) */
 930 #define RENEW_REQUESTED 5
 931 /* release, possibly manually requested (SIGUSR2) */
 932 #define RELEASED        6
 933 static smallint state;
 934
 935 static int udhcp_raw_socket(int ifindex)
 936 {
 937         int fd;
 938         struct sockaddr_ll sock;
 939
 940         /*
 941          * Comment:
 942          *
 943          *      I've selected not to see LL header, so BPF doesn't see it, too.
 944          *      The filter may also pass non-IP and non-ARP packets, but we do
 945          *      a more complete check when receiving the message in userspace.
 946          *
 947          * and filter shamelessly stolen from:
 948          *
 949          *      http://www.flamewarmaster.de/software/dhcpclient/
 950          *
 951          * There are a few other interesting ideas on that page (look under
 952          * "Motivation").  Use of netlink events is most interesting.  Think
 953          * of various network servers listening for events and reconfiguring.
 954          * That would obsolete sending HUP signals and/or make use of restarts.
 955          *
 956          * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
 957          * License: GPL v2.
 958          *
 959          * TODO: make conditional?
 960          */
 961         static const struct sock_filter filter_instr[] = {
 962                 /* load 9th byte (protocol) */
 963                 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
 964                 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
 965                 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
 966                 /* L1: load halfword from offset 6 (flags and frag offset) */
 967                 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
 968                 /* jump to L4 if any bits in frag offset field are set, else to L2 */
 969                 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
 970                 /* L2: skip IP header (load index reg with header len) */
 971                 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
 972                 /* load udp destination port from halfword[header_len + 2] */
 973                 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
 974                 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
 975                 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
 976                 /* L3: accept packet */
 977                 BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
 978                 /* L4: discard packet */
 979                 BPF_STMT(BPF_RET|BPF_K, 0),
 980         };
 981         static const struct sock_fprog filter_prog = {
 982                 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
 983                 /* casting const away: */
 984                 .filter = (struct sock_filter *) filter_instr,
 985         };
 986
 987         log1("Opening raw socket on ifindex %d", ifindex); //log2?
 988
 989         fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
 990         log1("Got raw socket fd %d", fd); //log2?
 991
 992         sock.sll_family = AF_PACKET;
 993         sock.sll_protocol = htons(ETH_P_IP);
 994         sock.sll_ifindex = ifindex;
 995         xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
 996
 997         if (CLIENT_PORT == 68) {
 998                 /* Use only if standard port is in use */
 999                 /* Ignoring error (kernel may lack support for this) */
1000                 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1001                                 sizeof(filter_prog)) >= 0)
1002                         log1("Attached filter to raw socket fd %d", fd); // log?
1003         }
1004
1005         log1("Created raw socket");
1006
1007         return fd;
1008 }
1009
1010 static void change_listen_mode(int new_mode)
1011 {
1012         log1("Entering listen mode: %s",
1013                 new_mode != LISTEN_NONE
1014                         ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1015                         : "none"
1016         );
1017
1018         listen_mode = new_mode;
1019         if (sockfd >= 0) {
1020                 close(sockfd);
1021                 sockfd = -1;
1022         }
1023         if (new_mode == LISTEN_KERNEL)
1024                 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1025         else if (new_mode != LISTEN_NONE)
1026                 sockfd = udhcp_raw_socket(client_config.ifindex);
1027         /* else LISTEN_NONE: sockfd stays closed */
1028 }
1029
1030 /* Called only on SIGUSR1 */
1031 static void perform_renew(void)
1032 {
1033         bb_info_msg("Performing a DHCP renew");
1034         switch (state) {
1035         case BOUND:
1036                 change_listen_mode(LISTEN_KERNEL);
1037         case RENEWING:
1038         case REBINDING:
1039                 state = RENEW_REQUESTED;
1040                 break;
1041         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1042                 udhcp_run_script(NULL, "deconfig");
1043         case REQUESTING:
1044         case RELEASED:
1045                 change_listen_mode(LISTEN_RAW);
1046                 state = INIT_SELECTING;
1047                 break;
1048         case INIT_SELECTING:
1049                 break;
1050         }
1051 }
1052
1053 static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1054 {
1055         char buffer[sizeof("255.255.255.255")];
1056         struct in_addr temp_addr;
1057
1058         /* send release packet */
1059         if (state == BOUND || state == RENEWING || state == REBINDING) {
1060                 temp_addr.s_addr = server_addr;
1061                 strcpy(buffer, inet_ntoa(temp_addr));
1062                 temp_addr.s_addr = requested_ip;
1063                 bb_info_msg("Unicasting a release of %s to %s",
1064                                 inet_ntoa(temp_addr), buffer);
1065                 send_release(server_addr, requested_ip); /* unicast */
1066                 udhcp_run_script(NULL, "deconfig");
1067         }
1068         bb_info_msg("Entering released state");
1069
1070         change_listen_mode(LISTEN_NONE);
1071         state = RELEASED;
1072 }
1073
1074 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1075 {
1076         uint8_t *storage;
1077         int len = strnlen(str, 255);
1078         storage = xzalloc(len + extra + OPT_DATA);
1079         storage[OPT_CODE] = code;
1080         storage[OPT_LEN] = len + extra;
1081         memcpy(storage + extra + OPT_DATA, str, len);
1082         return storage;
1083 }
1084
1085 #if BB_MMU
1086 static void client_background(void)
1087 {
1088         bb_daemonize(0);
1089         logmode &= ~LOGMODE_STDIO;
1090         /* rewrite pidfile, as our pid is different now */
1091         write_pidfile(client_config.pidfile);
1092 }
1093 #endif
1094
1095 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1096 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1097 //usage:#else
1098 //usage:# define IF_UDHCP_VERBOSE(...)
1099 //usage:#endif
1100 //usage:#define udhcpc_trivial_usage
1101 //usage:       "[-fbnq"IF_UDHCP_VERBOSE("v")"oCRB] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
1102 //usage:       "        [-V VENDOR] [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
1103 //usage:#define udhcpc_full_usage "\n"
1104 //usage:        IF_LONG_OPTS(
1105 //usage:     "\n        -i,--interface IFACE    Interface to use (default eth0)"
1106 //usage:     "\n        -p,--pidfile FILE       Create pidfile"
1107 //usage:     "\n        -s,--script PROG        Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1108 //usage:     "\n        -B,--broadcast          Request broadcast replies"
1109 //usage:     "\n        -t,--retries N          Send up to N discover packets"
1110 //usage:     "\n        -T,--timeout N          Pause between packets (default 3 seconds)"
1111 //usage:     "\n        -A,--tryagain N         Wait N seconds after failure (default 20)"
1112 //usage:     "\n        -f,--foreground         Run in foreground"
1113 //usage:        USE_FOR_MMU(
1114 //usage:     "\n        -b,--background         Background if lease is not obtained"
1115 //usage:        )
1116 //usage:     "\n        -n,--now                Exit if lease is not obtained"
1117 //usage:     "\n        -q,--quit               Exit after obtaining lease"
1118 //usage:     "\n        -R,--release            Release IP on exit"
1119 //usage:     "\n        -S,--syslog             Log to syslog too"
1120 //usage:        IF_FEATURE_UDHCP_PORT(
1121 //usage:     "\n        -P,--client-port N      Use port N (default 68)"
1122 //usage:        )
1123 //usage:        IF_FEATURE_UDHCPC_ARPING(
1124 //usage:     "\n        -a,--arping             Use arping to validate offered address"
1125 //usage:        )
1126 //usage:     "\n        -O,--request-option OPT Request option OPT from server (cumulative)"
1127 //usage:     "\n        -o,--no-default-options Don't request any options (unless -O is given)"
1128 //usage:     "\n        -r,--request IP         Request this IP address"
1129 //usage:     "\n        -x OPT:VAL              Include option OPT in sent packets (cumulative)"
1130 //usage:     "\n                                Examples of string, numeric, and hex byte opts:"
1131 //usage:     "\n                                -x hostname:bbox - option 12"
1132 //usage:     "\n                                -x lease:3600 - option 51 (lease time)"
1133 //usage:     "\n                                -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1134 //usage:     "\n        -F,--fqdn NAME          Ask server to update DNS mapping for NAME"
1135 //usage:     "\n        -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1136 //usage:     "\n        -C,--clientid-none      Don't send MAC as client identifier"
1137 //usage:        IF_UDHCP_VERBOSE(
1138 //usage:     "\n        -v                      Verbose"
1139 //usage:        )
1140 //usage:        )
1141 //usage:        IF_NOT_LONG_OPTS(
1142 //usage:     "\n        -i IFACE        Interface to use (default eth0)"
1143 //usage:     "\n        -p FILE         Create pidfile"
1144 //usage:     "\n        -s PROG         Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1145 //usage:     "\n        -B              Request broadcast replies"
1146 //usage:     "\n        -t N            Send up to N discover packets"
1147 //usage:     "\n        -T N            Pause between packets (default 3 seconds)"
1148 //usage:     "\n        -A N            Wait N seconds (default 20) after failure"
1149 //usage:     "\n        -f              Run in foreground"
1150 //usage:        USE_FOR_MMU(
1151 //usage:     "\n        -b              Background if lease is not obtained"
1152 //usage:        )
1153 //usage:     "\n        -n              Exit if lease is not obtained"
1154 //usage:     "\n        -q              Exit after obtaining lease"
1155 //usage:     "\n        -R              Release IP on exit"
1156 //usage:     "\n        -S              Log to syslog too"
1157 //usage:        IF_FEATURE_UDHCP_PORT(
1158 //usage:     "\n        -P N            Use port N (default 68)"
1159 //usage:        )
1160 //usage:        IF_FEATURE_UDHCPC_ARPING(
1161 //usage:     "\n        -a              Use arping to validate offered address"
1162 //usage:        )
1163 //usage:     "\n        -O OPT          Request option OPT from server (cumulative)"
1164 //usage:     "\n        -o              Don't request any options (unless -O is given)"
1165 //usage:     "\n        -r IP           Request this IP address"
1166 //usage:     "\n        -x OPT:VAL      Include option OPT in sent packets (cumulative)"
1167 //usage:     "\n                        Examples of string, numeric, and hex byte opts:"
1168 //usage:     "\n                        -x hostname:bbox - option 12"
1169 //usage:     "\n                        -x lease:3600 - option 51 (lease time)"
1170 //usage:     "\n                        -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1171 //usage:     "\n        -F NAME         Ask server to update DNS mapping for NAME"
1172 //usage:     "\n        -V VENDOR       Vendor identifier (default 'udhcp VERSION')"
1173 //usage:     "\n        -C              Don't send MAC as client identifier"
1174 //usage:        IF_UDHCP_VERBOSE(
1175 //usage:     "\n        -v              Verbose"
1176 //usage:        )
1177 //usage:        )
1178 //usage:     "\nSignals:"
1179 //usage:     "\n        USR1    Renew lease"
1180 //usage:     "\n        USR2    Release lease"
1181
1182
1183 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1184 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1185 {
1186         uint8_t *temp, *message;
1187         const char *str_V, *str_h, *str_F, *str_r;
1188         IF_FEATURE_UDHCP_PORT(char *str_P;)
1189         void *clientid_mac_ptr;
1190         llist_t *list_O = NULL;
1191         llist_t *list_x = NULL;
1192         int tryagain_timeout = 20;
1193         int discover_timeout = 3;
1194         int discover_retries = 3;
1195         uint32_t server_addr = server_addr; /* for compiler */
1196         uint32_t requested_ip = 0;
1197         uint32_t xid = xid; /* for compiler */
1198         int packet_num;
1199         int timeout; /* must be signed */
1200         unsigned already_waited_sec;
1201         unsigned opt;
1202         int max_fd;
1203         int retval;
1204         fd_set rfds;
1205
1206         /* Default options */
1207         IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1208         IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1209         client_config.interface = "eth0";
1210         client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1211         str_V = "udhcp "BB_VER;
1212
1213         /* Parse command line */
1214         /* O,x: list; -T,-t,-A take numeric param */
1215         opt_complementary = "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
1216         IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1217         opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1218                 USE_FOR_MMU("b")
1219                 IF_FEATURE_UDHCPC_ARPING("a")
1220                 IF_FEATURE_UDHCP_PORT("P:")
1221                 "v"
1222                 , &str_V, &str_h, &str_h, &str_F
1223                 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1224                 , &client_config.script /* s */
1225                 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1226                 , &list_O
1227                 , &list_x
1228                 IF_FEATURE_UDHCP_PORT(, &str_P)
1229                 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1230         );
1231         if (opt & (OPT_h|OPT_H)) {
1232                 //msg added 2011-11
1233                 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1234                 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1235         }
1236         if (opt & OPT_F) {
1237                 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1238                 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1239                 /* Flag bits: 0000NEOS
1240                  * S: 1 = Client requests server to update A RR in DNS as well as PTR
1241                  * O: 1 = Server indicates to client that DNS has been updated regardless
1242                  * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1243                  *    not "host.domain.com". Format 0 is obsolete.
1244                  * N: 1 = Client requests server to not update DNS (S must be 0 then)
1245                  * Two [0] bytes which follow are deprecated and must be 0.
1246                  */
1247                 client_config.fqdn[OPT_DATA + 0] = 0x1;
1248                 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1249                 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1250         }
1251         if (opt & OPT_r)
1252                 requested_ip = inet_addr(str_r);
1253 #if ENABLE_FEATURE_UDHCP_PORT
1254         if (opt & OPT_P) {
1255                 CLIENT_PORT = xatou16(str_P);
1256                 SERVER_PORT = CLIENT_PORT - 1;
1257         }
1258 #endif
1259         if (opt & OPT_o)
1260                 client_config.no_default_options = 1;
1261         while (list_O) {
1262                 char *optstr = llist_pop(&list_O);
1263                 unsigned n = bb_strtou(optstr, NULL, 0);
1264                 if (errno || n > 254) {
1265                         n = udhcp_option_idx(optstr);
1266                         n = dhcp_optflags[n].code;
1267                 }
1268                 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1269         }
1270         while (list_x) {
1271                 char *optstr = llist_pop(&list_x);
1272                 char *colon = strchr(optstr, ':');
1273                 if (colon)
1274                         *colon = ' ';
1275                 /* now it looks similar to udhcpd's config file line:
1276                  * "optname optval", using the common routine: */
1277                 udhcp_str2optset(optstr, &client_config.options);
1278         }
1279
1280         if (udhcp_read_interface(client_config.interface,
1281                         &client_config.ifindex,
1282                         NULL,
1283                         client_config.client_mac)
1284         ) {
1285                 return 1;
1286         }
1287
1288         clientid_mac_ptr = NULL;
1289         if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1290                 /* not suppressed and not set, set the default client ID */
1291                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1292                 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1293                 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1294                 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1295         }
1296         if (str_V[0] != '\0') {
1297                 // can drop -V, str_V, client_config.vendorclass,
1298                 // but need to add "vendor" to the list of recognized
1299                 // string opts for this to work;
1300                 // and need to tweak add_client_options() too...
1301                 // ...so the question is, should we?
1302                 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1303                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1304         }
1305
1306 #if !BB_MMU
1307         /* on NOMMU reexec (i.e., background) early */
1308         if (!(opt & OPT_f)) {
1309                 bb_daemonize_or_rexec(0 /* flags */, argv);
1310                 logmode = LOGMODE_NONE;
1311         }
1312 #endif
1313         if (opt & OPT_S) {
1314                 openlog(applet_name, LOG_PID, LOG_DAEMON);
1315                 logmode |= LOGMODE_SYSLOG;
1316         }
1317
1318         /* Make sure fd 0,1,2 are open */
1319         bb_sanitize_stdio();
1320         /* Equivalent of doing a fflush after every \n */
1321         setlinebuf(stdout);
1322         /* Create pidfile */
1323         write_pidfile(client_config.pidfile);
1324         /* Goes to stdout (unless NOMMU) and possibly syslog */
1325         bb_info_msg("%s (v"BB_VER") started", applet_name);
1326         /* Set up the signal pipe */
1327         udhcp_sp_setup();
1328         /* We want random_xid to be random... */
1329         srand(monotonic_us());
1330
1331         state = INIT_SELECTING;
1332         udhcp_run_script(NULL, "deconfig");
1333         change_listen_mode(LISTEN_RAW);
1334         packet_num = 0;
1335         timeout = 0;
1336         already_waited_sec = 0;
1337
1338         /* Main event loop. select() waits on signal pipe and possibly
1339          * on sockfd.
1340          * "continue" statements in code below jump to the top of the loop.
1341          */
1342         for (;;) {
1343                 struct timeval tv;
1344                 struct dhcp_packet packet;
1345                 /* silence "uninitialized!" warning */
1346                 unsigned timestamp_before_wait = timestamp_before_wait;
1347
1348                 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1349
1350                 /* Was opening raw or udp socket here
1351                  * if (listen_mode != LISTEN_NONE && sockfd < 0),
1352                  * but on fast network renew responses return faster
1353                  * than we open sockets. Thus this code is moved
1354                  * to change_listen_mode(). Thus we open listen socket
1355                  * BEFORE we send renew request (see "case BOUND:"). */
1356
1357                 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1358
1359                 tv.tv_sec = timeout - already_waited_sec;
1360                 tv.tv_usec = 0;
1361                 retval = 0;
1362                 /* If we already timed out, fall through with retval = 0, else... */
1363                 if ((int)tv.tv_sec > 0) {
1364                         timestamp_before_wait = (unsigned)monotonic_sec();
1365                         log1("Waiting on select...");
1366                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1367                         if (retval < 0) {
1368                                 /* EINTR? A signal was caught, don't panic */
1369                                 if (errno == EINTR) {
1370                                         already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1371                                         continue;
1372                                 }
1373                                 /* Else: an error occured, panic! */
1374                                 bb_perror_msg_and_die("select");
1375                         }
1376                 }
1377
1378                 /* If timeout dropped to zero, time to become active:
1379                  * resend discover/renew/whatever
1380                  */
1381                 if (retval == 0) {
1382                         /* When running on a bridge, the ifindex may have changed
1383                          * (e.g. if member interfaces were added/removed
1384                          * or if the status of the bridge changed).
1385                          * Refresh ifindex and client_mac:
1386                          */
1387                         if (udhcp_read_interface(client_config.interface,
1388                                         &client_config.ifindex,
1389                                         NULL,
1390                                         client_config.client_mac)
1391                         ) {
1392                                 goto ret0; /* iface is gone? */
1393                         }
1394                         if (clientid_mac_ptr)
1395                                 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1396
1397                         /* We will restart the wait in any case */
1398                         already_waited_sec = 0;
1399
1400                         switch (state) {
1401                         case INIT_SELECTING:
1402                                 if (packet_num < discover_retries) {
1403                                         if (packet_num == 0)
1404                                                 xid = random_xid();
1405                                         /* broadcast */
1406                                         send_discover(xid, requested_ip);
1407                                         timeout = discover_timeout;
1408                                         packet_num++;
1409                                         continue;
1410                                 }
1411  leasefail:
1412                                 udhcp_run_script(NULL, "leasefail");
1413 #if BB_MMU /* -b is not supported on NOMMU */
1414                                 if (opt & OPT_b) { /* background if no lease */
1415                                         bb_info_msg("No lease, forking to background");
1416                                         client_background();
1417                                         /* do not background again! */
1418                                         opt = ((opt & ~OPT_b) | OPT_f);
1419                                 } else
1420 #endif
1421                                 if (opt & OPT_n) { /* abort if no lease */
1422                                         bb_info_msg("No lease, failing");
1423                                         retval = 1;
1424                                         goto ret;
1425                                 }
1426                                 /* wait before trying again */
1427                                 timeout = tryagain_timeout;
1428                                 packet_num = 0;
1429                                 continue;
1430                         case REQUESTING:
1431                                 if (packet_num < discover_retries) {
1432                                         /* send broadcast select packet */
1433                                         send_select(xid, server_addr, requested_ip);
1434                                         timeout = discover_timeout;
1435                                         packet_num++;
1436                                         continue;
1437                                 }
1438                                 /* Timed out, go back to init state.
1439                                  * "discover...select...discover..." loops
1440                                  * were seen in the wild. Treat them similarly
1441                                  * to "no response to discover" case */
1442                                 change_listen_mode(LISTEN_RAW);
1443                                 state = INIT_SELECTING;
1444                                 goto leasefail;
1445                         case BOUND:
1446                                 /* 1/2 lease passed, enter renewing state */
1447                                 state = RENEWING;
1448                                 client_config.first_secs = 0; /* make secs field count from 0 */
1449                                 change_listen_mode(LISTEN_KERNEL);
1450                                 log1("Entering renew state");
1451                                 /* fall right through */
1452                         case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1453                         case_RENEW_REQUESTED:
1454                         case RENEWING:
1455                                 if (timeout > 60) {
1456                                         /* send an unicast renew request */
1457                         /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1458                          * a new UDP socket for sending inside send_renew.
1459                          * I hazard to guess existing listening socket
1460                          * is somehow conflicting with it, but why is it
1461                          * not deterministic then?! Strange.
1462                          * Anyway, it does recover by eventually failing through
1463                          * into INIT_SELECTING state.
1464                          */
1465                                         send_renew(xid, server_addr, requested_ip);
1466                                         timeout >>= 1;
1467                                         continue;
1468                                 }
1469                                 /* Timed out, enter rebinding state */
1470                                 log1("Entering rebinding state");
1471                                 state = REBINDING;
1472                                 /* fall right through */
1473                         case REBINDING:
1474                                 /* Switch to bcast receive */
1475                                 change_listen_mode(LISTEN_RAW);
1476                                 /* Lease is *really* about to run out,
1477                                  * try to find DHCP server using broadcast */
1478                                 if (timeout > 0) {
1479                                         /* send a broadcast renew request */
1480                                         send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1481                                         timeout >>= 1;
1482                                         continue;
1483                                 }
1484                                 /* Timed out, enter init state */
1485                                 bb_info_msg("Lease lost, entering init state");
1486                                 udhcp_run_script(NULL, "deconfig");
1487                                 state = INIT_SELECTING;
1488                                 client_config.first_secs = 0; /* make secs field count from 0 */
1489                                 /*timeout = 0; - already is */
1490                                 packet_num = 0;
1491                                 continue;
1492                         /* case RELEASED: */
1493                         }
1494                         /* yah, I know, *you* say it would never happen */
1495                         timeout = INT_MAX;
1496                         continue; /* back to main loop */
1497                 } /* if select timed out */
1498
1499                 /* select() didn't timeout, something happened */
1500
1501                 /* Is it a signal? */
1502                 /* note: udhcp_sp_read checks FD_ISSET before reading */
1503                 switch (udhcp_sp_read(&rfds)) {
1504                 case SIGUSR1:
1505                         client_config.first_secs = 0; /* make secs field count from 0 */
1506                         already_waited_sec = 0;
1507                         perform_renew();
1508                         if (state == RENEW_REQUESTED) {
1509                                 /* We might be either on the same network
1510                                  * (in which case renew might work),
1511                                  * or we might be on a completely different one
1512                                  * (in which case renew won't ever succeed).
1513                                  * For the second case, must make sure timeout
1514                                  * is not too big, or else we can send
1515                                  * futile renew requests for hours.
1516                                  * (Ab)use -A TIMEOUT value (usually 20 sec)
1517                                  * as a cap on the timeout.
1518                                  */
1519                                 if (timeout > tryagain_timeout)
1520                                         timeout = tryagain_timeout;
1521                                 goto case_RENEW_REQUESTED;
1522                         }
1523                         /* Start things over */
1524                         packet_num = 0;
1525                         /* Kill any timeouts, user wants this to hurry along */
1526                         timeout = 0;
1527                         continue;
1528                 case SIGUSR2:
1529                         perform_release(server_addr, requested_ip);
1530                         timeout = INT_MAX;
1531                         continue;
1532                 case SIGTERM:
1533                         bb_info_msg("Received SIGTERM");
1534                         goto ret0;
1535                 }
1536
1537                 /* Is it a packet? */
1538                 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1539                         continue; /* no */
1540
1541                 {
1542                         int len;
1543
1544                         /* A packet is ready, read it */
1545                         if (listen_mode == LISTEN_KERNEL)
1546                                 len = udhcp_recv_kernel_packet(&packet, sockfd);
1547                         else
1548                                 len = udhcp_recv_raw_packet(&packet, sockfd);
1549                         if (len == -1) {
1550                                 /* Error is severe, reopen socket */
1551                                 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1552                                 sleep(discover_timeout); /* 3 seconds by default */
1553                                 change_listen_mode(listen_mode); /* just close and reopen */
1554                         }
1555                         /* If this packet will turn out to be unrelated/bogus,
1556                          * we will go back and wait for next one.
1557                          * Be sure timeout is properly decreased. */
1558                         already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1559                         if (len < 0)
1560                                 continue;
1561                 }
1562
1563                 if (packet.xid != xid) {
1564                         log1("xid %x (our is %x), ignoring packet",
1565                                 (unsigned)packet.xid, (unsigned)xid);
1566                         continue;
1567                 }
1568
1569                 /* Ignore packets that aren't for us */
1570                 if (packet.hlen != 6
1571                  || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1572                 ) {
1573 //FIXME: need to also check that last 10 bytes are zero
1574                         log1("chaddr does not match, ignoring packet"); // log2?
1575                         continue;
1576                 }
1577
1578                 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1579                 if (message == NULL) {
1580                         bb_error_msg("no message type option, ignoring packet");
1581                         continue;
1582                 }
1583
1584                 switch (state) {
1585                 case INIT_SELECTING:
1586                         /* Must be a DHCPOFFER */
1587                         if (*message == DHCPOFFER) {
1588 /* What exactly is server's IP? There are several values.
1589  * Example DHCP offer captured with tchdump:
1590  *
1591  * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1592  * BOOTP fields:
1593  * Your-IP 10.34.25.202
1594  * Server-IP 10.34.32.125   // "next server" IP
1595  * Gateway-IP 10.34.25.254  // relay's address (if DHCP relays are in use)
1596  * DHCP options:
1597  * DHCP-Message Option 53, length 1: Offer
1598  * Server-ID Option 54, length 4: 10.34.255.7       // "server ID"
1599  * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1600  *
1601  * We think that real server IP (one to use in renew/release)
1602  * is one in Server-ID option. But I am not 100% sure.
1603  * IP header's src and Gateway-IP (same in this example)
1604  * might work too.
1605  * "Next server" and router are definitely wrong ones to use, though...
1606  */
1607                                 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1608                                 if (!temp) {
1609                                         bb_error_msg("no server ID, ignoring packet");
1610                                         continue;
1611                                         /* still selecting - this server looks bad */
1612                                 }
1613                                 /* it IS unaligned sometimes, don't "optimize" */
1614                                 move_from_unaligned32(server_addr, temp);
1615                                 /*xid = packet.xid; - already is */
1616                                 requested_ip = packet.yiaddr;
1617
1618                                 /* enter requesting state */
1619                                 state = REQUESTING;
1620                                 timeout = 0;
1621                                 packet_num = 0;
1622                                 already_waited_sec = 0;
1623                         }
1624                         continue;
1625                 case REQUESTING:
1626                 case RENEWING:
1627                 case RENEW_REQUESTED:
1628                 case REBINDING:
1629                         if (*message == DHCPACK) {
1630                                 uint32_t lease_seconds;
1631                                 struct in_addr temp_addr;
1632
1633                                 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1634                                 if (!temp) {
1635                                         bb_error_msg("no lease time with ACK, using 1 hour lease");
1636                                         lease_seconds = 60 * 60;
1637                                 } else {
1638                                         /* it IS unaligned sometimes, don't "optimize" */
1639                                         move_from_unaligned32(lease_seconds, temp);
1640                                         lease_seconds = ntohl(lease_seconds);
1641                                         /* paranoia: must not be too small and not prone to overflows */
1642                                         if (lease_seconds < 0x10)
1643                                                 lease_seconds = 0x10;
1644                                         if (lease_seconds >= 0x10000000)
1645                                                 lease_seconds = 0x0fffffff;
1646                                 }
1647 #if ENABLE_FEATURE_UDHCPC_ARPING
1648                                 if (opt & OPT_a) {
1649 /* RFC 2131 3.1 paragraph 5:
1650  * "The client receives the DHCPACK message with configuration
1651  * parameters. The client SHOULD perform a final check on the
1652  * parameters (e.g., ARP for allocated network address), and notes
1653  * the duration of the lease specified in the DHCPACK message. At this
1654  * point, the client is configured. If the client detects that the
1655  * address is already in use (e.g., through the use of ARP),
1656  * the client MUST send a DHCPDECLINE message to the server and restarts
1657  * the configuration process..." */
1658                                         if (!arpping(packet.yiaddr,
1659                                                         NULL,
1660                                                         (uint32_t) 0,
1661                                                         client_config.client_mac,
1662                                                         client_config.interface)
1663                                         ) {
1664                                                 bb_info_msg("Offered address is in use "
1665                                                         "(got ARP reply), declining");
1666                                                 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1667
1668                                                 if (state != REQUESTING)
1669                                                         udhcp_run_script(NULL, "deconfig");
1670                                                 change_listen_mode(LISTEN_RAW);
1671                                                 state = INIT_SELECTING;
1672                                                 client_config.first_secs = 0; /* make secs field count from 0 */
1673                                                 requested_ip = 0;
1674                                                 timeout = tryagain_timeout;
1675                                                 packet_num = 0;
1676                                                 already_waited_sec = 0;
1677                                                 continue; /* back to main loop */
1678                                         }
1679                                 }
1680 #endif
1681                                 /* enter bound state */
1682                                 timeout = lease_seconds / 2;
1683                                 temp_addr.s_addr = packet.yiaddr;
1684                                 bb_info_msg("Lease of %s obtained, lease time %u",
1685                                         inet_ntoa(temp_addr), (unsigned)lease_seconds);
1686                                 requested_ip = packet.yiaddr;
1687                                 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1688
1689                                 state = BOUND;
1690                                 change_listen_mode(LISTEN_NONE);
1691                                 if (opt & OPT_q) { /* quit after lease */
1692                                         goto ret0;
1693                                 }
1694                                 /* future renew failures should not exit (JM) */
1695                                 opt &= ~OPT_n;
1696 #if BB_MMU /* NOMMU case backgrounded earlier */
1697                                 if (!(opt & OPT_f)) {
1698                                         client_background();
1699                                         /* do not background again! */
1700                                         opt = ((opt & ~OPT_b) | OPT_f);
1701                                 }
1702 #endif
1703                                 /* make future renew packets use different xid */
1704                                 /* xid = random_xid(); ...but why bother? */
1705                                 already_waited_sec = 0;
1706                                 continue; /* back to main loop */
1707                         }
1708                         if (*message == DHCPNAK) {
1709                                 /* return to init state */
1710                                 bb_info_msg("Received DHCP NAK");
1711                                 udhcp_run_script(&packet, "nak");
1712                                 if (state != REQUESTING)
1713                                         udhcp_run_script(NULL, "deconfig");
1714                                 change_listen_mode(LISTEN_RAW);
1715                                 sleep(3); /* avoid excessive network traffic */
1716                                 state = INIT_SELECTING;
1717                                 client_config.first_secs = 0; /* make secs field count from 0 */
1718                                 requested_ip = 0;
1719                                 timeout = 0;
1720                                 packet_num = 0;
1721                                 already_waited_sec = 0;
1722                         }
1723                         continue;
1724                 /* case BOUND: - ignore all packets */
1725                 /* case RELEASED: - ignore all packets */
1726                 }
1727                 /* back to main loop */
1728         } /* for (;;) - main loop ends */
1729
1730  ret0:
1731         if (opt & OPT_R) /* release on quit */
1732                 perform_release(server_addr, requested_ip);
1733         retval = 0;
1734  ret:
1735         /*if (client_config.pidfile) - remove_pidfile has its own check */
1736                 remove_pidfile(client_config.pidfile);
1737         return retval;
1738 }