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