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