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 <linux/filter.h>
  30 #include <linux/if_packet.h>
  31
  32 #ifndef PACKET_AUXDATA
  33 # define PACKET_AUXDATA 8
  34 struct tpacket_auxdata {
  35         uint32_t tp_status;
  36         uint32_t tp_len;
  37         uint32_t tp_snaplen;
  38         uint16_t tp_mac;
  39         uint16_t tp_net;
  40         uint16_t tp_vlan_tci;
  41         uint16_t tp_padding;
  42 };
  43 #endif
  44
  45
  46 /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
  47
  48
  49 #if ENABLE_LONG_OPTS
  50 static const char udhcpc_longopts[] ALIGN1 =
  51         "clientid-none\0"  No_argument       "C"
  52         "vendorclass\0"    Required_argument "V"
  53         "hostname\0"       Required_argument "H"
  54         "fqdn\0"           Required_argument "F"
  55         "interface\0"      Required_argument "i"
  56         "now\0"            No_argument       "n"
  57         "pidfile\0"        Required_argument "p"
  58         "quit\0"           No_argument       "q"
  59         "release\0"        No_argument       "R"
  60         "request\0"        Required_argument "r"
  61         "script\0"         Required_argument "s"
  62         "timeout\0"        Required_argument "T"
  63         "retries\0"        Required_argument "t"
  64         "tryagain\0"       Required_argument "A"
  65         "syslog\0"         No_argument       "S"
  66         "request-option\0" Required_argument "O"
  67         "no-default-options\0" No_argument   "o"
  68         "foreground\0"     No_argument       "f"
  69         "background\0"     No_argument       "b"
  70         "broadcast\0"      No_argument       "B"
  71         IF_FEATURE_UDHCPC_ARPING("arping\0"     Optional_argument "a")
  72         IF_FEATURE_UDHCP_PORT("client-port\0"   Required_argument "P")
  73         ;
  74 #endif
  75 /* Must match getopt32 option string order */
  76 enum {
  77         OPT_C = 1 << 0,
  78         OPT_V = 1 << 1,
  79         OPT_H = 1 << 2,
  80         OPT_h = 1 << 3,
  81         OPT_F = 1 << 4,
  82         OPT_i = 1 << 5,
  83         OPT_n = 1 << 6,
  84         OPT_p = 1 << 7,
  85         OPT_q = 1 << 8,
  86         OPT_R = 1 << 9,
  87         OPT_r = 1 << 10,
  88         OPT_s = 1 << 11,
  89         OPT_T = 1 << 12,
  90         OPT_t = 1 << 13,
  91         OPT_S = 1 << 14,
  92         OPT_A = 1 << 15,
  93         OPT_O = 1 << 16,
  94         OPT_o = 1 << 17,
  95         OPT_x = 1 << 18,
  96         OPT_f = 1 << 19,
  97         OPT_B = 1 << 20,
  98 /* The rest has variable bit positions, need to be clever */
  99         OPTBIT_B = 20,
 100         USE_FOR_MMU(             OPTBIT_b,)
 101         IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
 102         IF_FEATURE_UDHCP_PORT(   OPTBIT_P,)
 103         USE_FOR_MMU(             OPT_b = 1 << OPTBIT_b,)
 104         IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
 105         IF_FEATURE_UDHCP_PORT(   OPT_P = 1 << OPTBIT_P,)
 106 };
 107
 108
 109 /*** Script execution code ***/
 110
 111 /* get a rough idea of how long an option will be (rounding up...) */
 112 static const uint8_t len_of_option_as_string[] = {
 113         [OPTION_IP              ] = sizeof("255.255.255.255 "),
 114         [OPTION_IP_PAIR         ] = sizeof("255.255.255.255 ") * 2,
 115         [OPTION_STATIC_ROUTES   ] = sizeof("255.255.255.255/32 255.255.255.255 "),
 116         [OPTION_6RD             ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
 117         [OPTION_STRING          ] = 1,
 118         [OPTION_STRING_HOST     ] = 1,
 119 #if ENABLE_FEATURE_UDHCP_RFC3397
 120         [OPTION_DNS_STRING      ] = 1, /* unused */
 121         /* Hmmm, this severely overestimates size if SIP_SERVERS option
 122          * is in domain name form: N-byte option in binary form
 123          * mallocs ~16*N bytes. But it is freed almost at once.
 124          */
 125         [OPTION_SIP_SERVERS     ] = sizeof("255.255.255.255 "),
 126 #endif
 127 //      [OPTION_BOOLEAN         ] = sizeof("yes "),
 128         [OPTION_U8              ] = sizeof("255 "),
 129         [OPTION_U16             ] = sizeof("65535 "),
 130 //      [OPTION_S16             ] = sizeof("-32768 "),
 131         [OPTION_U32             ] = sizeof("4294967295 "),
 132         [OPTION_S32             ] = sizeof("-2147483684 "),
 133 };
 134
 135 /* note: ip is a pointer to an IP in network order, possibly misaliged */
 136 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
 137 {
 138         return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
 139 }
 140
 141 /* really simple implementation, just count the bits */
 142 static int mton(uint32_t mask)
 143 {
 144         int i = 0;
 145         mask = ntohl(mask); /* 111110000-like bit pattern */
 146         while (mask) {
 147                 i++;
 148                 mask <<= 1;
 149         }
 150         return i;
 151 }
 152
 153 #if ENABLE_FEATURE_UDHCPC_SANITIZEOPT
 154 /* Check if a given label represents a valid DNS label
 155  * Return pointer to the first character after the label upon success,
 156  * NULL otherwise.
 157  * See RFC1035, 2.3.1
 158  */
 159 /* We don't need to be particularly anal. For example, allowing _, hyphen
 160  * at the end, or leading and trailing dots would be ok, since it
 161  * can't be used for attacks. (Leading hyphen can be, if someone uses
 162  * cmd "$hostname"
 163  * in the script: then hostname may be treated as an option)
 164  */
 165 static const char *valid_domain_label(const char *label)
 166 {
 167         unsigned char ch;
 168         unsigned pos = 0;
 169
 170         for (;;) {
 171                 ch = *label;
 172                 if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
 173                         if (ch < '0' || ch > '9') {
 174                                 if (ch == '\0' || ch == '.')
 175                                         return label;
 176                                 /* DNS allows only '-', but we are more permissive */
 177                                 if (ch != '-' && ch != '_')
 178                                         return NULL;
 179                         }
 180                 }
 181                 label++;
 182                 pos++;
 183                 //Do we want this?
 184                 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
 185                 //      return NULL;
 186         }
 187 }
 188
 189 /* Check if a given name represents a valid DNS name */
 190 /* See RFC1035, 2.3.1 */
 191 static int good_hostname(const char *name)
 192 {
 193         //const char *start = name;
 194
 195         for (;;) {
 196                 name = valid_domain_label(name);
 197                 if (!name)
 198                         return 0;
 199                 if (!name[0])
 200                         return 1;
 201                         //Do we want this?
 202                         //return ((name - start) < 1025); /* NS_MAXDNAME */
 203                 name++;
 204         }
 205 }
 206 #else
 207 # define good_hostname(name) 1
 208 #endif
 209
 210 /* Create "opt_name=opt_value" string */
 211 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
 212 {
 213         unsigned upper_length;
 214         int len, type, optlen;
 215         char *dest, *ret;
 216
 217         /* option points to OPT_DATA, need to go back to get OPT_LEN */
 218         len = option[-OPT_DATA + OPT_LEN];
 219
 220         type = optflag->flags & OPTION_TYPE_MASK;
 221         optlen = dhcp_option_lengths[type];
 222         upper_length = len_of_option_as_string[type]
 223                 * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
 224
 225         dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
 226         dest += sprintf(ret, "%s=", opt_name);
 227
 228         while (len >= optlen) {
 229                 switch (type) {
 230                 case OPTION_IP:
 231                 case OPTION_IP_PAIR:
 232                         dest += sprint_nip(dest, "", option);
 233                         if (type == OPTION_IP)
 234                                 break;
 235                         dest += sprint_nip(dest, "/", option + 4);
 236                         break;
 237 //              case OPTION_BOOLEAN:
 238 //                      dest += sprintf(dest, *option ? "yes" : "no");
 239 //                      break;
 240                 case OPTION_U8:
 241                         dest += sprintf(dest, "%u", *option);
 242                         break;
 243 //              case OPTION_S16:
 244                 case OPTION_U16: {
 245                         uint16_t val_u16;
 246                         move_from_unaligned16(val_u16, option);
 247                         dest += sprintf(dest, "%u", ntohs(val_u16));
 248                         break;
 249                 }
 250                 case OPTION_S32:
 251                 case OPTION_U32: {
 252                         uint32_t val_u32;
 253                         move_from_unaligned32(val_u32, option);
 254                         dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
 255                         break;
 256                 }
 257                 /* Note: options which use 'return' instead of 'break'
 258                  * (for example, OPTION_STRING) skip the code which handles
 259                  * the case of list of options.
 260                  */
 261                 case OPTION_STRING:
 262                 case OPTION_STRING_HOST:
 263                         memcpy(dest, option, len);
 264                         dest[len] = '\0';
 265                         if (type == OPTION_STRING_HOST && !good_hostname(dest))
 266                                 safe_strncpy(dest, "bad", len);
 267                         return ret;
 268                 case OPTION_STATIC_ROUTES: {
 269                         /* Option binary format:
 270                          * mask [one byte, 0..32]
 271                          * ip [big endian, 0..4 bytes depending on mask]
 272                          * router [big endian, 4 bytes]
 273                          * may be repeated
 274                          *
 275                          * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
 276                          */
 277                         const char *pfx = "";
 278
 279                         while (len >= 1 + 4) { /* mask + 0-byte ip + router */
 280                                 uint32_t nip;
 281                                 uint8_t *p;
 282                                 unsigned mask;
 283                                 int bytes;
 284
 285                                 mask = *option++;
 286                                 if (mask > 32)
 287                                         break;
 288                                 len--;
 289
 290                                 nip = 0;
 291                                 p = (void*) &nip;
 292                                 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
 293                                 while (--bytes >= 0) {
 294                                         *p++ = *option++;
 295                                         len--;
 296                                 }
 297                                 if (len < 4)
 298                                         break;
 299
 300                                 /* print ip/mask */
 301                                 dest += sprint_nip(dest, pfx, (void*) &nip);
 302                                 pfx = " ";
 303                                 dest += sprintf(dest, "/%u ", mask);
 304                                 /* print router */
 305                                 dest += sprint_nip(dest, "", option);
 306                                 option += 4;
 307                                 len -= 4;
 308                         }
 309
 310                         return ret;
 311                 }
 312                 case OPTION_6RD:
 313                         /* Option binary format (see RFC 5969):
 314                          *  0                   1                   2                   3
 315                          *  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
 316                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 317                          * |  OPTION_6RD   | option-length |  IPv4MaskLen  |  6rdPrefixLen |
 318                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 319                          * |                           6rdPrefix                           |
 320                          * ...                        (16 octets)                        ...
 321                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 322                          * ...                   6rdBRIPv4Address(es)                    ...
 323                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 324                          * We convert it to a string
 325                          * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
 326                          *
 327                          * Sanity check: ensure that our length is at least 22 bytes, that
 328                          * IPv4MaskLen <= 32,
 329                          * 6rdPrefixLen <= 128,
 330                          * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
 331                          * (2nd condition need no check - it follows from 1st and 3rd).
 332                          * Else, return envvar with empty value ("optname=")
 333                          */
 334                         if (len >= (1 + 1 + 16 + 4)
 335                          && option[0] <= 32
 336                          && (option[1] + 32 - option[0]) <= 128
 337                         ) {
 338                                 /* IPv4MaskLen */
 339                                 dest += sprintf(dest, "%u ", *option++);
 340                                 /* 6rdPrefixLen */
 341                                 dest += sprintf(dest, "%u ", *option++);
 342                                 /* 6rdPrefix */
 343                                 dest += sprint_nip6(dest, /* "", */ option);
 344                                 option += 16;
 345                                 len -= 1 + 1 + 16 + 4;
 346                                 /* "+ 4" above corresponds to the length of IPv4 addr
 347                                  * we consume in the loop below */
 348                                 while (1) {
 349                                         /* 6rdBRIPv4Address(es) */
 350                                         dest += sprint_nip(dest, " ", option);
 351                                         option += 4;
 352                                         len -= 4; /* do we have yet another 4+ bytes? */
 353                                         if (len < 0)
 354                                                 break; /* no */
 355                                 }
 356                         }
 357
 358                         return ret;
 359 #if ENABLE_FEATURE_UDHCP_RFC3397
 360                 case OPTION_DNS_STRING:
 361                         /* unpack option into dest; use ret for prefix (i.e., "optname=") */
 362                         dest = dname_dec(option, len, ret);
 363                         if (dest) {
 364                                 free(ret);
 365                                 return dest;
 366                         }
 367                         /* error. return "optname=" string */
 368                         return ret;
 369                 case OPTION_SIP_SERVERS:
 370                         /* Option binary format:
 371                          * type: byte
 372                          * type=0: domain names, dns-compressed
 373                          * type=1: IP addrs
 374                          */
 375                         option++;
 376                         len--;
 377                         if (option[-1] == 0) {
 378                                 dest = dname_dec(option, len, ret);
 379                                 if (dest) {
 380                                         free(ret);
 381                                         return dest;
 382                                 }
 383                         } else
 384                         if (option[-1] == 1) {
 385                                 const char *pfx = "";
 386                                 while (1) {
 387                                         len -= 4;
 388                                         if (len < 0)
 389                                                 break;
 390                                         dest += sprint_nip(dest, pfx, option);
 391                                         pfx = " ";
 392                                         option += 4;
 393                                 }
 394                         }
 395                         return ret;
 396 #endif
 397                 } /* switch */
 398
 399                 /* If we are here, try to format any remaining data
 400                  * in the option as another, similarly-formatted option
 401                  */
 402                 option += optlen;
 403                 len -= optlen;
 404 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
 405 // Should we bail out/warn if we see multi-ip option which is
 406 // not allowed to be such (for example, DHCP_BROADCAST)? -
 407                 if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
 408                         break;
 409                 *dest++ = ' ';
 410                 *dest = '\0';
 411         } /* while */
 412
 413         return ret;
 414 }
 415
 416 /* put all the parameters into the environment */
 417 static char **fill_envp(struct dhcp_packet *packet)
 418 {
 419         int envc;
 420         int i;
 421         char **envp, **curr;
 422         const char *opt_name;
 423         uint8_t *temp;
 424         uint8_t overload = 0;
 425
 426 #define BITMAP unsigned
 427 #define BBITS (sizeof(BITMAP) * 8)
 428 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
 429 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
 430         BITMAP found_opts[256 / BBITS];
 431
 432         memset(found_opts, 0, sizeof(found_opts));
 433
 434         /* We need 6 elements for:
 435          * "interface=IFACE"
 436          * "ip=N.N.N.N" from packet->yiaddr
 437          * "siaddr=IP" from packet->siaddr_nip (unless 0)
 438          * "boot_file=FILE" from packet->file (unless overloaded)
 439          * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
 440          * terminating NULL
 441          */
 442         envc = 6;
 443         /* +1 element for each option, +2 for subnet option: */
 444         if (packet) {
 445                 /* note: do not search for "pad" (0) and "end" (255) options */
 446 //TODO: change logic to scan packet _once_
 447                 for (i = 1; i < 255; i++) {
 448                         temp = udhcp_get_option(packet, i);
 449                         if (temp) {
 450                                 if (i == DHCP_OPTION_OVERLOAD)
 451                                         overload = *temp;
 452                                 else if (i == DHCP_SUBNET)
 453                                         envc++; /* for $mask */
 454                                 envc++;
 455                                 /*if (i != DHCP_MESSAGE_TYPE)*/
 456                                 FOUND_OPTS(i) |= BMASK(i);
 457                         }
 458                 }
 459         }
 460         curr = envp = xzalloc(sizeof(envp[0]) * envc);
 461
 462         *curr = xasprintf("interface=%s", client_config.interface);
 463         putenv(*curr++);
 464
 465         if (!packet)
 466                 return envp;
 467
 468         /* Export BOOTP fields. Fields we don't (yet?) export:
 469          * uint8_t op;      // always BOOTREPLY
 470          * uint8_t htype;   // hardware address type. 1 = 10mb ethernet
 471          * uint8_t hlen;    // hardware address length
 472          * uint8_t hops;    // used by relay agents only
 473          * uint32_t xid;
 474          * uint16_t secs;   // elapsed since client began acquisition/renewal
 475          * uint16_t flags;  // only one flag so far: bcast. Never set by server
 476          * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
 477          *                  // if during renew server wants to give us differn IP?)
 478          * uint32_t gateway_nip; // relay agent IP address
 479          * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
 480          * TODO: export gateway_nip as $giaddr?
 481          */
 482         /* Most important one: yiaddr as $ip */
 483         *curr = xmalloc(sizeof("ip=255.255.255.255"));
 484         sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
 485         putenv(*curr++);
 486         if (packet->siaddr_nip) {
 487                 /* IP address of next server to use in bootstrap */
 488                 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
 489                 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
 490                 putenv(*curr++);
 491         }
 492         if (!(overload & FILE_FIELD) && packet->file[0]) {
 493                 /* watch out for invalid packets */
 494                 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
 495                 putenv(*curr++);
 496         }
 497         if (!(overload & SNAME_FIELD) && packet->sname[0]) {
 498                 /* watch out for invalid packets */
 499                 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
 500                 putenv(*curr++);
 501         }
 502
 503         /* Export known DHCP options */
 504         opt_name = dhcp_option_strings;
 505         i = 0;
 506         while (*opt_name) {
 507                 uint8_t code = dhcp_optflags[i].code;
 508                 BITMAP *found_ptr = &FOUND_OPTS(code);
 509                 BITMAP found_mask = BMASK(code);
 510                 if (!(*found_ptr & found_mask))
 511                         goto next;
 512                 *found_ptr &= ~found_mask; /* leave only unknown options */
 513                 temp = udhcp_get_option(packet, code);
 514                 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
 515                 putenv(*curr++);
 516                 if (code == DHCP_SUBNET) {
 517                         /* Subnet option: make things like "$ip/$mask" possible */
 518                         uint32_t subnet;
 519                         move_from_unaligned32(subnet, temp);
 520                         *curr = xasprintf("mask=%u", mton(subnet));
 521                         putenv(*curr++);
 522                 }
 523  next:
 524                 opt_name += strlen(opt_name) + 1;
 525                 i++;
 526         }
 527         /* Export unknown options */
 528         for (i = 0; i < 256;) {
 529                 BITMAP bitmap = FOUND_OPTS(i);
 530                 if (!bitmap) {
 531                         i += BBITS;
 532                         continue;
 533                 }
 534                 if (bitmap & BMASK(i)) {
 535                         unsigned len, ofs;
 536
 537                         temp = udhcp_get_option(packet, i);
 538                         /* udhcp_get_option returns ptr to data portion,
 539                          * need to go back to get len
 540                          */
 541                         len = temp[-OPT_DATA + OPT_LEN];
 542                         *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
 543                         ofs = sprintf(*curr, "opt%u=", i);
 544                         *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
 545                         putenv(*curr++);
 546                 }
 547                 i++;
 548         }
 549
 550         return envp;
 551 }
 552
 553 /* Call a script with a par file and env vars */
 554 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
 555 {
 556         char **envp, **curr;
 557         char *argv[3];
 558
 559         envp = fill_envp(packet);
 560
 561         /* call script */
 562         log1("Executing %s %s", client_config.script, name);
 563         argv[0] = (char*) client_config.script;
 564         argv[1] = (char*) name;
 565         argv[2] = NULL;
 566         spawn_and_wait(argv);
 567
 568         for (curr = envp; *curr; curr++) {
 569                 log2(" %s", *curr);
 570                 bb_unsetenv_and_free(*curr);
 571         }
 572         free(envp);
 573 }
 574
 575
 576 /*** Sending/receiving packets ***/
 577
 578 static ALWAYS_INLINE uint32_t random_xid(void)
 579 {
 580         return rand();
 581 }
 582
 583 /* Initialize the packet with the proper defaults */
 584 static void init_packet(struct dhcp_packet *packet, char type)
 585 {
 586         uint16_t secs;
 587
 588         /* Fill in: op, htype, hlen, cookie fields; message type option: */
 589         udhcp_init_header(packet, type);
 590
 591         packet->xid = random_xid();
 592
 593         client_config.last_secs = monotonic_sec();
 594         if (client_config.first_secs == 0)
 595                 client_config.first_secs = client_config.last_secs;
 596         secs = client_config.last_secs - client_config.first_secs;
 597         packet->secs = htons(secs);
 598
 599         memcpy(packet->chaddr, client_config.client_mac, 6);
 600         if (client_config.clientid)
 601                 udhcp_add_binary_option(packet, client_config.clientid);
 602 }
 603
 604 static void add_client_options(struct dhcp_packet *packet)
 605 {
 606         int i, end, len;
 607
 608         udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
 609
 610         /* Add a "param req" option with the list of options we'd like to have
 611          * from stubborn DHCP servers. Pull the data from the struct in common.c.
 612          * No bounds checking because it goes towards the head of the packet. */
 613         end = udhcp_end_option(packet->options);
 614         len = 0;
 615         for (i = 1; i < DHCP_END; i++) {
 616                 if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
 617                         packet->options[end + OPT_DATA + len] = i;
 618                         len++;
 619                 }
 620         }
 621         if (len) {
 622                 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
 623                 packet->options[end + OPT_LEN] = len;
 624                 packet->options[end + OPT_DATA + len] = DHCP_END;
 625         }
 626
 627         if (client_config.vendorclass)
 628                 udhcp_add_binary_option(packet, client_config.vendorclass);
 629         if (client_config.hostname)
 630                 udhcp_add_binary_option(packet, client_config.hostname);
 631         if (client_config.fqdn)
 632                 udhcp_add_binary_option(packet, client_config.fqdn);
 633
 634         /* Request broadcast replies if we have no IP addr */
 635         if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
 636                 packet->flags |= htons(BROADCAST_FLAG);
 637
 638         /* Add -x options if any */
 639         {
 640                 struct option_set *curr = client_config.options;
 641                 while (curr) {
 642                         udhcp_add_binary_option(packet, curr->data);
 643                         curr = curr->next;
 644                 }
 645 //              if (client_config.sname)
 646 //                      strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
 647 //              if (client_config.boot_file)
 648 //                      strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
 649         }
 650
 651         // This will be needed if we remove -V VENDOR_STR in favor of
 652         // -x vendor:VENDOR_STR
 653         //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
 654         //      /* not set, set the default vendor ID */
 655         //      ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
 656 }
 657
 658 /* RFC 2131
 659  * 4.4.4 Use of broadcast and unicast
 660  *
 661  * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
 662  * messages, unless the client knows the address of a DHCP server.
 663  * The client unicasts DHCPRELEASE messages to the server. Because
 664  * the client is declining the use of the IP address supplied by the server,
 665  * the client broadcasts DHCPDECLINE messages.
 666  *
 667  * When the DHCP client knows the address of a DHCP server, in either
 668  * INIT or REBOOTING state, the client may use that address
 669  * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
 670  * The client may also use unicast to send DHCPINFORM messages
 671  * to a known DHCP server. If the client receives no response to DHCP
 672  * messages sent to the IP address of a known DHCP server, the DHCP
 673  * client reverts to using the IP broadcast address.
 674  */
 675
 676 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
 677 {
 678         return udhcp_send_raw_packet(packet,
 679                 /*src*/ INADDR_ANY, CLIENT_PORT,
 680                 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
 681                 client_config.ifindex);
 682 }
 683
 684 static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
 685 {
 686         if (server)
 687                 return udhcp_send_kernel_packet(packet,
 688                         ciaddr, CLIENT_PORT,
 689                         server, SERVER_PORT);
 690         return raw_bcast_from_client_config_ifindex(packet);
 691 }
 692
 693 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
 694 /* NOINLINE: limit stack usage in caller */
 695 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
 696 {
 697         struct dhcp_packet packet;
 698
 699         /* Fill in: op, htype, hlen, cookie, chaddr fields,
 700          * random xid field (we override it below),
 701          * client-id option (unless -C), message type option:
 702          */
 703         init_packet(&packet, DHCPDISCOVER);
 704
 705         packet.xid = xid;
 706         if (requested)
 707                 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 708
 709         /* Add options: maxsize,
 710          * optionally: hostname, fqdn, vendorclass,
 711          * "param req" option according to -O, options specified with -x
 712          */
 713         add_client_options(&packet);
 714
 715         bb_info_msg("Sending discover...");
 716         return raw_bcast_from_client_config_ifindex(&packet);
 717 }
 718
 719 /* Broadcast a DHCP request message */
 720 /* RFC 2131 3.1 paragraph 3:
 721  * "The client _broadcasts_ a DHCPREQUEST message..."
 722  */
 723 /* NOINLINE: limit stack usage in caller */
 724 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
 725 {
 726         struct dhcp_packet packet;
 727         struct in_addr addr;
 728
 729 /*
 730  * RFC 2131 4.3.2 DHCPREQUEST message
 731  * ...
 732  * If the DHCPREQUEST message contains a 'server identifier'
 733  * option, the message is in response to a DHCPOFFER message.
 734  * Otherwise, the message is a request to verify or extend an
 735  * existing lease. If the client uses a 'client identifier'
 736  * in a DHCPREQUEST message, it MUST use that same 'client identifier'
 737  * in all subsequent messages. If the client included a list
 738  * of requested parameters in a DHCPDISCOVER message, it MUST
 739  * include that list in all subsequent messages.
 740  */
 741         /* Fill in: op, htype, hlen, cookie, chaddr fields,
 742          * random xid field (we override it below),
 743          * client-id option (unless -C), message type option:
 744          */
 745         init_packet(&packet, DHCPREQUEST);
 746
 747         packet.xid = xid;
 748         udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 749
 750         udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 751
 752         /* Add options: maxsize,
 753          * optionally: hostname, fqdn, vendorclass,
 754          * "param req" option according to -O, and options specified with -x
 755          */
 756         add_client_options(&packet);
 757
 758         addr.s_addr = requested;
 759         bb_info_msg("Sending select for %s...", inet_ntoa(addr));
 760         return raw_bcast_from_client_config_ifindex(&packet);
 761 }
 762
 763 /* Unicast or broadcast a DHCP renew message */
 764 /* NOINLINE: limit stack usage in caller */
 765 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
 766 {
 767         struct dhcp_packet packet;
 768
 769 /*
 770  * RFC 2131 4.3.2 DHCPREQUEST message
 771  * ...
 772  * DHCPREQUEST generated during RENEWING state:
 773  *
 774  * 'server identifier' MUST NOT be filled in, 'requested IP address'
 775  * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
 776  * client's IP address. In this situation, the client is completely
 777  * configured, and is trying to extend its lease. This message will
 778  * be unicast, so no relay agents will be involved in its
 779  * transmission.  Because 'giaddr' is therefore not filled in, the
 780  * DHCP server will trust the value in 'ciaddr', and use it when
 781  * replying to the client.
 782  */
 783         /* Fill in: op, htype, hlen, cookie, chaddr fields,
 784          * random xid field (we override it below),
 785          * client-id option (unless -C), message type option:
 786          */
 787         init_packet(&packet, DHCPREQUEST);
 788
 789         packet.xid = xid;
 790         packet.ciaddr = ciaddr;
 791
 792         /* Add options: maxsize,
 793          * optionally: hostname, fqdn, vendorclass,
 794          * "param req" option according to -O, and options specified with -x
 795          */
 796         add_client_options(&packet);
 797
 798         bb_info_msg("Sending renew...");
 799         return bcast_or_ucast(&packet, ciaddr, server);
 800 }
 801
 802 #if ENABLE_FEATURE_UDHCPC_ARPING
 803 /* Broadcast a DHCP decline message */
 804 /* NOINLINE: limit stack usage in caller */
 805 static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
 806 {
 807         struct dhcp_packet packet;
 808
 809         /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
 810          * client-id option (unless -C), message type option:
 811          */
 812         init_packet(&packet, DHCPDECLINE);
 813
 814 #if 0
 815         /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
 816          * but in case the server is buggy and wants DHCPDECLINE's xid
 817          * to match the xid which started entire handshake,
 818          * we use the same xid we used in initial DHCPDISCOVER:
 819          */
 820         packet.xid = xid;
 821 #endif
 822         /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
 823         udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 824
 825         udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 826
 827         bb_info_msg("Sending decline...");
 828         return raw_bcast_from_client_config_ifindex(&packet);
 829 }
 830 #endif
 831
 832 /* Unicast a DHCP release message */
 833 static int send_release(uint32_t server, uint32_t ciaddr)
 834 {
 835         struct dhcp_packet packet;
 836
 837         /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
 838          * client-id option (unless -C), message type option:
 839          */
 840         init_packet(&packet, DHCPRELEASE);
 841
 842         /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
 843         packet.ciaddr = ciaddr;
 844
 845         udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
 846
 847         bb_info_msg("Sending release...");
 848         /* Note: normally we unicast here since "server" is not zero.
 849          * However, there _are_ people who run "address-less" DHCP servers,
 850          * and reportedly ISC dhcp client and Windows allow that.
 851          */
 852         return bcast_or_ucast(&packet, ciaddr, server);
 853 }
 854
 855 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
 856 /* NOINLINE: limit stack usage in caller */
 857 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
 858 {
 859         int bytes;
 860         struct ip_udp_dhcp_packet packet;
 861         uint16_t check;
 862         unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
 863         struct iovec iov;
 864         struct msghdr msg;
 865         struct cmsghdr *cmsg;
 866
 867         /* used to use just safe_read(fd, &packet, sizeof(packet))
 868          * but we need to check for TP_STATUS_CSUMNOTREADY :(
 869          */
 870         iov.iov_base = &packet;
 871         iov.iov_len = sizeof(packet);
 872         memset(&msg, 0, sizeof(msg));
 873         msg.msg_iov = &iov;
 874         msg.msg_iovlen = 1;
 875         msg.msg_control = cmsgbuf;
 876         msg.msg_controllen = sizeof(cmsgbuf);
 877         for (;;) {
 878                 bytes = recvmsg(fd, &msg, 0);
 879                 if (bytes < 0) {
 880                         if (errno == EINTR)
 881                                 continue;
 882                         log1("Packet read error, ignoring");
 883                         /* NB: possible down interface, etc. Caller should pause. */
 884                         return bytes; /* returns -1 */
 885                 }
 886                 break;
 887         }
 888
 889         if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
 890                 log1("Packet is too short, ignoring");
 891                 return -2;
 892         }
 893
 894         if (bytes < ntohs(packet.ip.tot_len)) {
 895                 /* packet is bigger than sizeof(packet), we did partial read */
 896                 log1("Oversized packet, ignoring");
 897                 return -2;
 898         }
 899
 900         /* ignore any extra garbage bytes */
 901         bytes = ntohs(packet.ip.tot_len);
 902
 903         /* make sure its the right packet for us, and that it passes sanity checks */
 904         if (packet.ip.protocol != IPPROTO_UDP
 905          || packet.ip.version != IPVERSION
 906          || packet.ip.ihl != (sizeof(packet.ip) >> 2)
 907          || packet.udp.dest != htons(CLIENT_PORT)
 908         /* || bytes > (int) sizeof(packet) - can't happen */
 909          || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
 910         ) {
 911                 log1("Unrelated/bogus packet, ignoring");
 912                 return -2;
 913         }
 914
 915         /* verify IP checksum */
 916         check = packet.ip.check;
 917         packet.ip.check = 0;
 918         if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
 919                 log1("Bad IP header checksum, ignoring");
 920                 return -2;
 921         }
 922
 923         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 924                 if (cmsg->cmsg_level == SOL_PACKET
 925                  && cmsg->cmsg_type == PACKET_AUXDATA
 926                 ) {
 927                         /* some VMs don't checksum UDP and TCP data
 928                          * they send to the same physical machine,
 929                          * here we detect this case:
 930                          */
 931                         struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
 932                         if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
 933                                 goto skip_udp_sum_check;
 934                 }
 935         }
 936
 937         /* verify UDP checksum. IP header has to be modified for this */
 938         memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
 939         /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
 940         packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
 941         check = packet.udp.check;
 942         packet.udp.check = 0;
 943         if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
 944                 log1("Packet with bad UDP checksum received, ignoring");
 945                 return -2;
 946         }
 947  skip_udp_sum_check:
 948
 949         if (packet.data.cookie != htonl(DHCP_MAGIC)) {
 950                 bb_info_msg("Packet with bad magic, ignoring");
 951                 return -2;
 952         }
 953
 954         log1("Received a packet");
 955         udhcp_dump_packet(&packet.data);
 956
 957         bytes -= sizeof(packet.ip) + sizeof(packet.udp);
 958         memcpy(dhcp_pkt, &packet.data, bytes);
 959         return bytes;
 960 }
 961
 962
 963 /*** Main ***/
 964
 965 static int sockfd = -1;
 966
 967 #define LISTEN_NONE   0
 968 #define LISTEN_KERNEL 1
 969 #define LISTEN_RAW    2
 970 static smallint listen_mode;
 971
 972 /* initial state: (re)start DHCP negotiation */
 973 #define INIT_SELECTING  0
 974 /* discover was sent, DHCPOFFER reply received */
 975 #define REQUESTING      1
 976 /* select/renew was sent, DHCPACK reply received */
 977 #define BOUND           2
 978 /* half of lease passed, want to renew it by sending unicast renew requests */
 979 #define RENEWING        3
 980 /* renew requests were not answered, lease is almost over, send broadcast renew */
 981 #define REBINDING       4
 982 /* manually requested renew (SIGUSR1) */
 983 #define RENEW_REQUESTED 5
 984 /* release, possibly manually requested (SIGUSR2) */
 985 #define RELEASED        6
 986 static smallint state;
 987
 988 static int udhcp_raw_socket(int ifindex)
 989 {
 990         int fd;
 991         struct sockaddr_ll sock;
 992
 993         log1("Opening raw socket on ifindex %d", ifindex); //log2?
 994
 995         fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
 996         /* ^^^^^
 997          * SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
 998          * ETH_P_IP: want to receive only packets with IPv4 eth type
 999          */
1000         log1("Got raw socket fd"); //log2?
1001
1002         sock.sll_family = AF_PACKET;
1003         sock.sll_protocol = htons(ETH_P_IP);
1004         sock.sll_ifindex = ifindex;
1005         xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
1006
1007 #if 0 /* Several users reported breakage when BPF filter is used */
1008         if (CLIENT_PORT == 68) {
1009                 /* Use only if standard port is in use */
1010                 /*
1011                  *      I've selected not to see LL header, so BPF doesn't see it, too.
1012                  *      The filter may also pass non-IP and non-ARP packets, but we do
1013                  *      a more complete check when receiving the message in userspace.
1014                  *
1015                  * and filter shamelessly stolen from:
1016                  *
1017                  *      http://www.flamewarmaster.de/software/dhcpclient/
1018                  *
1019                  * There are a few other interesting ideas on that page (look under
1020                  * "Motivation").  Use of netlink events is most interesting.  Think
1021                  * of various network servers listening for events and reconfiguring.
1022                  * That would obsolete sending HUP signals and/or make use of restarts.
1023                  *
1024                  * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
1025                  * License: GPL v2.
1026                  */
1027                 static const struct sock_filter filter_instr[] = {
1028                         /* load 9th byte (protocol) */
1029                         BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
1030                         /* jump to L1 if it is IPPROTO_UDP, else to L4 */
1031                         BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
1032                         /* L1: load halfword from offset 6 (flags and frag offset) */
1033                         BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
1034                         /* jump to L4 if any bits in frag offset field are set, else to L2 */
1035                         BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1036                         /* L2: skip IP header (load index reg with header len) */
1037                         BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1038                         /* load udp destination port from halfword[header_len + 2] */
1039                         BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1040                         /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1041                         BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1042                         /* L3: accept packet ("accept 0x7fffffff bytes") */
1043                         /* Accepting 0xffffffff works too but kernel 2.6.19 is buggy */
1044                         BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
1045                         /* L4: discard packet ("accept zero bytes") */
1046                         BPF_STMT(BPF_RET|BPF_K, 0),
1047                 };
1048                 static const struct sock_fprog filter_prog = {
1049                         .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1050                         /* casting const away: */
1051                         .filter = (struct sock_filter *) filter_instr,
1052                 };
1053                 /* Ignoring error (kernel may lack support for this) */
1054                 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1055                                 sizeof(filter_prog)) >= 0)
1056                         log1("Attached filter to raw socket fd"); // log?
1057         }
1058 #endif
1059
1060         if (setsockopt_1(fd, SOL_PACKET, PACKET_AUXDATA) != 0) {
1061                 if (errno != ENOPROTOOPT)
1062                         log1("Can't set PACKET_AUXDATA on raw socket");
1063         }
1064
1065         log1("Created raw socket");
1066
1067         return fd;
1068 }
1069
1070 static void change_listen_mode(int new_mode)
1071 {
1072         log1("Entering listen mode: %s",
1073                 new_mode != LISTEN_NONE
1074                         ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1075                         : "none"
1076         );
1077
1078         listen_mode = new_mode;
1079         if (sockfd >= 0) {
1080                 close(sockfd);
1081                 sockfd = -1;
1082         }
1083         if (new_mode == LISTEN_KERNEL)
1084                 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1085         else if (new_mode != LISTEN_NONE)
1086                 sockfd = udhcp_raw_socket(client_config.ifindex);
1087         /* else LISTEN_NONE: sockfd stays closed */
1088 }
1089
1090 /* Called only on SIGUSR1 */
1091 static void perform_renew(void)
1092 {
1093         bb_info_msg("Performing a DHCP renew");
1094         switch (state) {
1095         case BOUND:
1096                 change_listen_mode(LISTEN_KERNEL);
1097         case RENEWING:
1098         case REBINDING:
1099                 state = RENEW_REQUESTED;
1100                 break;
1101         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1102                 udhcp_run_script(NULL, "deconfig");
1103         case REQUESTING:
1104         case RELEASED:
1105                 change_listen_mode(LISTEN_RAW);
1106                 state = INIT_SELECTING;
1107                 break;
1108         case INIT_SELECTING:
1109                 break;
1110         }
1111 }
1112
1113 static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1114 {
1115         char buffer[sizeof("255.255.255.255")];
1116         struct in_addr temp_addr;
1117
1118         /* send release packet */
1119         if (state == BOUND || state == RENEWING || state == REBINDING) {
1120                 temp_addr.s_addr = server_addr;
1121                 strcpy(buffer, inet_ntoa(temp_addr));
1122                 temp_addr.s_addr = requested_ip;
1123                 bb_info_msg("Unicasting a release of %s to %s",
1124                                 inet_ntoa(temp_addr), buffer);
1125                 send_release(server_addr, requested_ip); /* unicast */
1126                 udhcp_run_script(NULL, "deconfig");
1127         }
1128         bb_info_msg("Entering released state");
1129
1130         change_listen_mode(LISTEN_NONE);
1131         state = RELEASED;
1132 }
1133
1134 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1135 {
1136         uint8_t *storage;
1137         int len = strnlen(str, 255);
1138         storage = xzalloc(len + extra + OPT_DATA);
1139         storage[OPT_CODE] = code;
1140         storage[OPT_LEN] = len + extra;
1141         memcpy(storage + extra + OPT_DATA, str, len);
1142         return storage;
1143 }
1144
1145 #if BB_MMU
1146 static void client_background(void)
1147 {
1148         bb_daemonize(0);
1149         logmode &= ~LOGMODE_STDIO;
1150         /* rewrite pidfile, as our pid is different now */
1151         write_pidfile(client_config.pidfile);
1152 }
1153 #endif
1154
1155 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1156 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1157 //usage:#else
1158 //usage:# define IF_UDHCP_VERBOSE(...)
1159 //usage:#endif
1160 //usage:#define udhcpc_trivial_usage
1161 //usage:       "[-fbq"IF_UDHCP_VERBOSE("v")"RB]"IF_FEATURE_UDHCPC_ARPING(" [-a[MSEC]]")" [-t N] [-T SEC] [-A SEC/-n]\n"
1162 //usage:       "        [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
1163 //usage:       "        [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
1164 //usage:#define udhcpc_full_usage "\n"
1165 //usage:        IF_LONG_OPTS(
1166 //usage:     "\n        -i,--interface IFACE    Interface to use (default eth0)"
1167 //usage:        IF_FEATURE_UDHCP_PORT(
1168 //usage:     "\n        -P,--client-port PORT   Use PORT (default 68)"
1169 //usage:        )
1170 //usage:     "\n        -s,--script PROG        Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1171 //usage:     "\n        -p,--pidfile FILE       Create pidfile"
1172 //usage:     "\n        -B,--broadcast          Request broadcast replies"
1173 //usage:     "\n        -t,--retries N          Send up to N discover packets (default 3)"
1174 //usage:     "\n        -T,--timeout SEC        Pause between packets (default 3)"
1175 //usage:     "\n        -A,--tryagain SEC       Wait if lease is not obtained (default 20)"
1176 //usage:     "\n        -n,--now                Exit if lease is not obtained"
1177 //usage:     "\n        -q,--quit               Exit after obtaining lease"
1178 //usage:     "\n        -R,--release            Release IP on exit"
1179 //usage:     "\n        -f,--foreground         Run in foreground"
1180 //usage:        USE_FOR_MMU(
1181 //usage:     "\n        -b,--background         Background if lease is not obtained"
1182 //usage:        )
1183 //usage:     "\n        -S,--syslog             Log to syslog too"
1184 //usage:        IF_FEATURE_UDHCPC_ARPING(
1185 //usage:     "\n        -a[MSEC],--arping[=MSEC] Validate offered address with ARP ping"
1186 //usage:        )
1187 //usage:     "\n        -r,--request IP         Request this IP address"
1188 //usage:     "\n        -o,--no-default-options Don't request any options (unless -O is given)"
1189 //usage:     "\n        -O,--request-option OPT Request option OPT from server (cumulative)"
1190 //usage:     "\n        -x OPT:VAL              Include option OPT in sent packets (cumulative)"
1191 //usage:     "\n                                Examples of string, numeric, and hex byte opts:"
1192 //usage:     "\n                                -x hostname:bbox - option 12"
1193 //usage:     "\n                                -x lease:3600 - option 51 (lease time)"
1194 //usage:     "\n                                -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1195 //usage:     "\n        -F,--fqdn NAME          Ask server to update DNS mapping for NAME"
1196 //usage:     "\n        -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1197 //usage:     "\n        -C,--clientid-none      Don't send MAC as client identifier"
1198 //usage:        IF_UDHCP_VERBOSE(
1199 //usage:     "\n        -v                      Verbose"
1200 //usage:        )
1201 //usage:        )
1202 //usage:        IF_NOT_LONG_OPTS(
1203 //usage:     "\n        -i IFACE        Interface to use (default eth0)"
1204 //usage:        IF_FEATURE_UDHCP_PORT(
1205 //usage:     "\n        -P PORT         Use PORT (default 68)"
1206 //usage:        )
1207 //usage:     "\n        -s PROG         Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1208 //usage:     "\n        -p FILE         Create pidfile"
1209 //usage:     "\n        -B              Request broadcast replies"
1210 //usage:     "\n        -t N            Send up to N discover packets (default 3)"
1211 //usage:     "\n        -T SEC          Pause between packets (default 3)"
1212 //usage:     "\n        -A SEC          Wait if lease is not obtained (default 20)"
1213 //usage:     "\n        -n              Exit if lease is not obtained"
1214 //usage:     "\n        -q              Exit after obtaining lease"
1215 //usage:     "\n        -R              Release IP on exit"
1216 //usage:     "\n        -f              Run in foreground"
1217 //usage:        USE_FOR_MMU(
1218 //usage:     "\n        -b              Background if lease is not obtained"
1219 //usage:        )
1220 //usage:     "\n        -S              Log to syslog too"
1221 //usage:        IF_FEATURE_UDHCPC_ARPING(
1222 //usage:     "\n        -a[MSEC]        Validate offered address with ARP ping"
1223 //usage:        )
1224 //usage:     "\n        -r IP           Request this IP address"
1225 //usage:     "\n        -o              Don't request any options (unless -O is given)"
1226 //usage:     "\n        -O OPT          Request option OPT from server (cumulative)"
1227 //usage:     "\n        -x OPT:VAL      Include option OPT in sent packets (cumulative)"
1228 //usage:     "\n                        Examples of string, numeric, and hex byte opts:"
1229 //usage:     "\n                        -x hostname:bbox - option 12"
1230 //usage:     "\n                        -x lease:3600 - option 51 (lease time)"
1231 //usage:     "\n                        -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1232 //usage:     "\n        -F NAME         Ask server to update DNS mapping for NAME"
1233 //usage:     "\n        -V VENDOR       Vendor identifier (default 'udhcp VERSION')"
1234 //usage:     "\n        -C              Don't send MAC as client identifier"
1235 //usage:        IF_UDHCP_VERBOSE(
1236 //usage:     "\n        -v              Verbose"
1237 //usage:        )
1238 //usage:        )
1239 //usage:     "\nSignals:"
1240 //usage:     "\n        USR1    Renew lease"
1241 //usage:     "\n        USR2    Release lease"
1242
1243
1244 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1245 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1246 {
1247         uint8_t *message;
1248         const char *str_V, *str_h, *str_F, *str_r;
1249         IF_FEATURE_UDHCPC_ARPING(const char *str_a = "2000";)
1250         IF_FEATURE_UDHCP_PORT(char *str_P;)
1251         void *clientid_mac_ptr;
1252         llist_t *list_O = NULL;
1253         llist_t *list_x = NULL;
1254         int tryagain_timeout = 20;
1255         int discover_timeout = 3;
1256         int discover_retries = 3;
1257         uint32_t server_addr = server_addr; /* for compiler */
1258         uint32_t requested_ip = 0;
1259         uint32_t xid = xid; /* for compiler */
1260         int packet_num;
1261         int timeout; /* must be signed */
1262         unsigned already_waited_sec;
1263         unsigned opt;
1264         IF_FEATURE_UDHCPC_ARPING(unsigned arpping_ms;)
1265         int max_fd;
1266         int retval;
1267         fd_set rfds;
1268
1269         /* Default options */
1270         IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1271         IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1272         client_config.interface = "eth0";
1273         client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1274         str_V = "udhcp "BB_VER;
1275
1276         /* Parse command line */
1277         /* O,x: list; -T,-t,-A take numeric param */
1278         opt_complementary = "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
1279         IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1280         opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1281                 USE_FOR_MMU("b")
1282                 IF_FEATURE_UDHCPC_ARPING("a::")
1283                 IF_FEATURE_UDHCP_PORT("P:")
1284                 "v"
1285                 , &str_V, &str_h, &str_h, &str_F
1286                 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1287                 , &client_config.script /* s */
1288                 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1289                 , &list_O
1290                 , &list_x
1291                 IF_FEATURE_UDHCPC_ARPING(, &str_a)
1292                 IF_FEATURE_UDHCP_PORT(, &str_P)
1293                 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1294         );
1295         if (opt & (OPT_h|OPT_H)) {
1296                 //msg added 2011-11
1297                 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1298                 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1299         }
1300         if (opt & OPT_F) {
1301                 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1302                 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1303                 /* Flag bits: 0000NEOS
1304                  * S: 1 = Client requests server to update A RR in DNS as well as PTR
1305                  * O: 1 = Server indicates to client that DNS has been updated regardless
1306                  * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1307                  *    not "host.domain.com". Format 0 is obsolete.
1308                  * N: 1 = Client requests server to not update DNS (S must be 0 then)
1309                  * Two [0] bytes which follow are deprecated and must be 0.
1310                  */
1311                 client_config.fqdn[OPT_DATA + 0] = 0x1;
1312                 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1313                 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1314         }
1315         if (opt & OPT_r)
1316                 requested_ip = inet_addr(str_r);
1317 #if ENABLE_FEATURE_UDHCP_PORT
1318         if (opt & OPT_P) {
1319                 CLIENT_PORT = xatou16(str_P);
1320                 SERVER_PORT = CLIENT_PORT - 1;
1321         }
1322 #endif
1323         IF_FEATURE_UDHCPC_ARPING(arpping_ms = xatou(str_a);)
1324         while (list_O) {
1325                 char *optstr = llist_pop(&list_O);
1326                 unsigned n = bb_strtou(optstr, NULL, 0);
1327                 if (errno || n > 254) {
1328                         n = udhcp_option_idx(optstr);
1329                         n = dhcp_optflags[n].code;
1330                 }
1331                 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1332         }
1333         if (!(opt & OPT_o)) {
1334                 unsigned i, n;
1335                 for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1336                         if (dhcp_optflags[i].flags & OPTION_REQ) {
1337                                 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1338                         }
1339                 }
1340         }
1341         while (list_x) {
1342                 char *optstr = llist_pop(&list_x);
1343                 char *colon = strchr(optstr, ':');
1344                 if (colon)
1345                         *colon = ' ';
1346                 /* now it looks similar to udhcpd's config file line:
1347                  * "optname optval", using the common routine: */
1348                 udhcp_str2optset(optstr, &client_config.options);
1349         }
1350
1351         if (udhcp_read_interface(client_config.interface,
1352                         &client_config.ifindex,
1353                         NULL,
1354                         client_config.client_mac)
1355         ) {
1356                 return 1;
1357         }
1358
1359         clientid_mac_ptr = NULL;
1360         if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1361                 /* not suppressed and not set, set the default client ID */
1362                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1363                 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1364                 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1365                 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1366         }
1367         if (str_V[0] != '\0') {
1368                 // can drop -V, str_V, client_config.vendorclass,
1369                 // but need to add "vendor" to the list of recognized
1370                 // string opts for this to work;
1371                 // and need to tweak add_client_options() too...
1372                 // ...so the question is, should we?
1373                 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1374                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1375         }
1376
1377 #if !BB_MMU
1378         /* on NOMMU reexec (i.e., background) early */
1379         if (!(opt & OPT_f)) {
1380                 bb_daemonize_or_rexec(0 /* flags */, argv);
1381                 logmode = LOGMODE_NONE;
1382         }
1383 #endif
1384         if (opt & OPT_S) {
1385                 openlog(applet_name, LOG_PID, LOG_DAEMON);
1386                 logmode |= LOGMODE_SYSLOG;
1387         }
1388
1389         /* Make sure fd 0,1,2 are open */
1390         bb_sanitize_stdio();
1391         /* Equivalent of doing a fflush after every \n */
1392         setlinebuf(stdout);
1393         /* Create pidfile */
1394         write_pidfile(client_config.pidfile);
1395         /* Goes to stdout (unless NOMMU) and possibly syslog */
1396         bb_info_msg("%s (v"BB_VER") started", applet_name);
1397         /* Set up the signal pipe */
1398         udhcp_sp_setup();
1399         /* We want random_xid to be random... */
1400         srand(monotonic_us());
1401
1402         state = INIT_SELECTING;
1403         udhcp_run_script(NULL, "deconfig");
1404         change_listen_mode(LISTEN_RAW);
1405         packet_num = 0;
1406         timeout = 0;
1407         already_waited_sec = 0;
1408
1409         /* Main event loop. select() waits on signal pipe and possibly
1410          * on sockfd.
1411          * "continue" statements in code below jump to the top of the loop.
1412          */
1413         for (;;) {
1414                 struct timeval tv;
1415                 struct dhcp_packet packet;
1416                 /* silence "uninitialized!" warning */
1417                 unsigned timestamp_before_wait = timestamp_before_wait;
1418
1419                 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1420
1421                 /* Was opening raw or udp socket here
1422                  * if (listen_mode != LISTEN_NONE && sockfd < 0),
1423                  * but on fast network renew responses return faster
1424                  * than we open sockets. Thus this code is moved
1425                  * to change_listen_mode(). Thus we open listen socket
1426                  * BEFORE we send renew request (see "case BOUND:"). */
1427
1428                 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1429
1430                 tv.tv_sec = timeout - already_waited_sec;
1431                 tv.tv_usec = 0;
1432                 retval = 0;
1433                 /* If we already timed out, fall through with retval = 0, else... */
1434                 if ((int)tv.tv_sec > 0) {
1435                         log1("Waiting on select %u seconds", (int)tv.tv_sec);
1436                         timestamp_before_wait = (unsigned)monotonic_sec();
1437                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1438                         if (retval < 0) {
1439                                 /* EINTR? A signal was caught, don't panic */
1440                                 if (errno == EINTR) {
1441                                         already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1442                                         continue;
1443                                 }
1444                                 /* Else: an error occured, panic! */
1445                                 bb_perror_msg_and_die("select");
1446                         }
1447                 }
1448
1449                 /* If timeout dropped to zero, time to become active:
1450                  * resend discover/renew/whatever
1451                  */
1452                 if (retval == 0) {
1453                         /* When running on a bridge, the ifindex may have changed
1454                          * (e.g. if member interfaces were added/removed
1455                          * or if the status of the bridge changed).
1456                          * Refresh ifindex and client_mac:
1457                          */
1458                         if (udhcp_read_interface(client_config.interface,
1459                                         &client_config.ifindex,
1460                                         NULL,
1461                                         client_config.client_mac)
1462                         ) {
1463                                 goto ret0; /* iface is gone? */
1464                         }
1465                         if (clientid_mac_ptr)
1466                                 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1467
1468                         /* We will restart the wait in any case */
1469                         already_waited_sec = 0;
1470
1471                         switch (state) {
1472                         case INIT_SELECTING:
1473                                 if (!discover_retries || packet_num < discover_retries) {
1474                                         if (packet_num == 0)
1475                                                 xid = random_xid();
1476                                         /* broadcast */
1477                                         send_discover(xid, requested_ip);
1478                                         timeout = discover_timeout;
1479                                         packet_num++;
1480                                         continue;
1481                                 }
1482  leasefail:
1483                                 udhcp_run_script(NULL, "leasefail");
1484 #if BB_MMU /* -b is not supported on NOMMU */
1485                                 if (opt & OPT_b) { /* background if no lease */
1486                                         bb_info_msg("No lease, forking to background");
1487                                         client_background();
1488                                         /* do not background again! */
1489                                         opt = ((opt & ~OPT_b) | OPT_f);
1490                                 } else
1491 #endif
1492                                 if (opt & OPT_n) { /* abort if no lease */
1493                                         bb_info_msg("No lease, failing");
1494                                         retval = 1;
1495                                         goto ret;
1496                                 }
1497                                 /* wait before trying again */
1498                                 timeout = tryagain_timeout;
1499                                 packet_num = 0;
1500                                 continue;
1501                         case REQUESTING:
1502                                 if (!discover_retries || packet_num < discover_retries) {
1503                                         /* send broadcast select packet */
1504                                         send_select(xid, server_addr, requested_ip);
1505                                         timeout = discover_timeout;
1506                                         packet_num++;
1507                                         continue;
1508                                 }
1509                                 /* Timed out, go back to init state.
1510                                  * "discover...select...discover..." loops
1511                                  * were seen in the wild. Treat them similarly
1512                                  * to "no response to discover" case */
1513                                 change_listen_mode(LISTEN_RAW);
1514                                 state = INIT_SELECTING;
1515                                 goto leasefail;
1516                         case BOUND:
1517                                 /* 1/2 lease passed, enter renewing state */
1518                                 state = RENEWING;
1519                                 client_config.first_secs = 0; /* make secs field count from 0 */
1520                                 change_listen_mode(LISTEN_KERNEL);
1521                                 log1("Entering renew state");
1522                                 /* fall right through */
1523                         case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1524                         case_RENEW_REQUESTED:
1525                         case RENEWING:
1526                                 if (timeout > 60) {
1527                                         /* send an unicast renew request */
1528                         /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1529                          * a new UDP socket for sending inside send_renew.
1530                          * I hazard to guess existing listening socket
1531                          * is somehow conflicting with it, but why is it
1532                          * not deterministic then?! Strange.
1533                          * Anyway, it does recover by eventually failing through
1534                          * into INIT_SELECTING state.
1535                          */
1536                                         send_renew(xid, server_addr, requested_ip);
1537                                         timeout >>= 1;
1538                                         continue;
1539                                 }
1540                                 /* Timed out, enter rebinding state */
1541                                 log1("Entering rebinding state");
1542                                 state = REBINDING;
1543                                 /* fall right through */
1544                         case REBINDING:
1545                                 /* Switch to bcast receive */
1546                                 change_listen_mode(LISTEN_RAW);
1547                                 /* Lease is *really* about to run out,
1548                                  * try to find DHCP server using broadcast */
1549                                 if (timeout > 0) {
1550                                         /* send a broadcast renew request */
1551                                         send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1552                                         timeout >>= 1;
1553                                         continue;
1554                                 }
1555                                 /* Timed out, enter init state */
1556                                 bb_info_msg("Lease lost, entering init state");
1557                                 udhcp_run_script(NULL, "deconfig");
1558                                 state = INIT_SELECTING;
1559                                 client_config.first_secs = 0; /* make secs field count from 0 */
1560                                 /*timeout = 0; - already is */
1561                                 packet_num = 0;
1562                                 continue;
1563                         /* case RELEASED: */
1564                         }
1565                         /* yah, I know, *you* say it would never happen */
1566                         timeout = INT_MAX;
1567                         continue; /* back to main loop */
1568                 } /* if select timed out */
1569
1570                 /* select() didn't timeout, something happened */
1571
1572                 /* Is it a signal? */
1573                 /* note: udhcp_sp_read checks FD_ISSET before reading */
1574                 switch (udhcp_sp_read(&rfds)) {
1575                 case SIGUSR1:
1576                         client_config.first_secs = 0; /* make secs field count from 0 */
1577                         already_waited_sec = 0;
1578                         perform_renew();
1579                         if (state == RENEW_REQUESTED) {
1580                                 /* We might be either on the same network
1581                                  * (in which case renew might work),
1582                                  * or we might be on a completely different one
1583                                  * (in which case renew won't ever succeed).
1584                                  * For the second case, must make sure timeout
1585                                  * is not too big, or else we can send
1586                                  * futile renew requests for hours.
1587                                  * (Ab)use -A TIMEOUT value (usually 20 sec)
1588                                  * as a cap on the timeout.
1589                                  */
1590                                 if (timeout > tryagain_timeout)
1591                                         timeout = tryagain_timeout;
1592                                 goto case_RENEW_REQUESTED;
1593                         }
1594                         /* Start things over */
1595                         packet_num = 0;
1596                         /* Kill any timeouts, user wants this to hurry along */
1597                         timeout = 0;
1598                         continue;
1599                 case SIGUSR2:
1600                         perform_release(server_addr, requested_ip);
1601                         timeout = INT_MAX;
1602                         continue;
1603                 case SIGTERM:
1604                         bb_info_msg("Received SIGTERM");
1605                         goto ret0;
1606                 }
1607
1608                 /* Is it a packet? */
1609                 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1610                         continue; /* no */
1611
1612                 {
1613                         int len;
1614
1615                         /* A packet is ready, read it */
1616                         if (listen_mode == LISTEN_KERNEL)
1617                                 len = udhcp_recv_kernel_packet(&packet, sockfd);
1618                         else
1619                                 len = udhcp_recv_raw_packet(&packet, sockfd);
1620                         if (len == -1) {
1621                                 /* Error is severe, reopen socket */
1622                                 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1623                                 sleep(discover_timeout); /* 3 seconds by default */
1624                                 change_listen_mode(listen_mode); /* just close and reopen */
1625                         }
1626                         /* If this packet will turn out to be unrelated/bogus,
1627                          * we will go back and wait for next one.
1628                          * Be sure timeout is properly decreased. */
1629                         already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1630                         if (len < 0)
1631                                 continue;
1632                 }
1633
1634                 if (packet.xid != xid) {
1635                         log1("xid %x (our is %x), ignoring packet",
1636                                 (unsigned)packet.xid, (unsigned)xid);
1637                         continue;
1638                 }
1639
1640                 /* Ignore packets that aren't for us */
1641                 if (packet.hlen != 6
1642                  || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1643                 ) {
1644 //FIXME: need to also check that last 10 bytes are zero
1645                         log1("chaddr does not match, ignoring packet"); // log2?
1646                         continue;
1647                 }
1648
1649                 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1650                 if (message == NULL) {
1651                         bb_error_msg("no message type option, ignoring packet");
1652                         continue;
1653                 }
1654
1655                 switch (state) {
1656                 case INIT_SELECTING:
1657                         /* Must be a DHCPOFFER */
1658                         if (*message == DHCPOFFER) {
1659                                 uint8_t *temp;
1660
1661 /* What exactly is server's IP? There are several values.
1662  * Example DHCP offer captured with tchdump:
1663  *
1664  * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1665  * BOOTP fields:
1666  * Your-IP 10.34.25.202
1667  * Server-IP 10.34.32.125   // "next server" IP
1668  * Gateway-IP 10.34.25.254  // relay's address (if DHCP relays are in use)
1669  * DHCP options:
1670  * DHCP-Message Option 53, length 1: Offer
1671  * Server-ID Option 54, length 4: 10.34.255.7       // "server ID"
1672  * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1673  *
1674  * We think that real server IP (one to use in renew/release)
1675  * is one in Server-ID option. But I am not 100% sure.
1676  * IP header's src and Gateway-IP (same in this example)
1677  * might work too.
1678  * "Next server" and router are definitely wrong ones to use, though...
1679  */
1680 /* We used to ignore pcakets without DHCP_SERVER_ID.
1681  * I've got user reports from people who run "address-less" servers.
1682  * They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
1683  * They say ISC DHCP client supports this case.
1684  */
1685                                 server_addr = 0;
1686                                 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1687                                 if (!temp) {
1688                                         bb_error_msg("no server ID, using 0.0.0.0");
1689                                 } else {
1690                                         /* it IS unaligned sometimes, don't "optimize" */
1691                                         move_from_unaligned32(server_addr, temp);
1692                                 }
1693                                 /*xid = packet.xid; - already is */
1694                                 requested_ip = packet.yiaddr;
1695
1696                                 /* enter requesting state */
1697                                 state = REQUESTING;
1698                                 timeout = 0;
1699                                 packet_num = 0;
1700                                 already_waited_sec = 0;
1701                         }
1702                         continue;
1703                 case REQUESTING:
1704                 case RENEWING:
1705                 case RENEW_REQUESTED:
1706                 case REBINDING:
1707                         if (*message == DHCPACK) {
1708                                 unsigned start;
1709                                 uint32_t lease_seconds;
1710                                 struct in_addr temp_addr;
1711                                 uint8_t *temp;
1712
1713                                 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1714                                 if (!temp) {
1715                                         bb_error_msg("no lease time with ACK, using 1 hour lease");
1716                                         lease_seconds = 60 * 60;
1717                                 } else {
1718                                         /* it IS unaligned sometimes, don't "optimize" */
1719                                         move_from_unaligned32(lease_seconds, temp);
1720                                         lease_seconds = ntohl(lease_seconds);
1721                                         /* paranoia: must not be too small and not prone to overflows */
1722                                         if (lease_seconds < 0x10)
1723                                                 lease_seconds = 0x10;
1724                                         if (lease_seconds >= 0x10000000)
1725                                                 lease_seconds = 0x0fffffff;
1726                                 }
1727 #if ENABLE_FEATURE_UDHCPC_ARPING
1728                                 if (opt & OPT_a) {
1729 /* RFC 2131 3.1 paragraph 5:
1730  * "The client receives the DHCPACK message with configuration
1731  * parameters. The client SHOULD perform a final check on the
1732  * parameters (e.g., ARP for allocated network address), and notes
1733  * the duration of the lease specified in the DHCPACK message. At this
1734  * point, the client is configured. If the client detects that the
1735  * address is already in use (e.g., through the use of ARP),
1736  * the client MUST send a DHCPDECLINE message to the server and restarts
1737  * the configuration process..." */
1738                                         if (!arpping(packet.yiaddr,
1739                                                         NULL,
1740                                                         (uint32_t) 0,
1741                                                         client_config.client_mac,
1742                                                         client_config.interface,
1743                                                         arpping_ms)
1744                                         ) {
1745                                                 bb_info_msg("Offered address is in use "
1746                                                         "(got ARP reply), declining");
1747                                                 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1748
1749                                                 if (state != REQUESTING)
1750                                                         udhcp_run_script(NULL, "deconfig");
1751                                                 change_listen_mode(LISTEN_RAW);
1752                                                 state = INIT_SELECTING;
1753                                                 client_config.first_secs = 0; /* make secs field count from 0 */
1754                                                 requested_ip = 0;
1755                                                 timeout = tryagain_timeout;
1756                                                 packet_num = 0;
1757                                                 already_waited_sec = 0;
1758                                                 continue; /* back to main loop */
1759                                         }
1760                                 }
1761 #endif
1762                                 /* enter bound state */
1763                                 temp_addr.s_addr = packet.yiaddr;
1764                                 bb_info_msg("Lease of %s obtained, lease time %u",
1765                                         inet_ntoa(temp_addr), (unsigned)lease_seconds);
1766                                 requested_ip = packet.yiaddr;
1767
1768                                 start = monotonic_sec();
1769                                 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1770                                 already_waited_sec = (unsigned)monotonic_sec() - start;
1771                                 timeout = lease_seconds / 2;
1772                                 if ((unsigned)timeout < already_waited_sec) {
1773                                         /* Something went wrong. Back to discover state */
1774                                         timeout = already_waited_sec = 0;
1775                                 }
1776
1777                                 state = BOUND;
1778                                 change_listen_mode(LISTEN_NONE);
1779                                 if (opt & OPT_q) { /* quit after lease */
1780                                         goto ret0;
1781                                 }
1782                                 /* future renew failures should not exit (JM) */
1783                                 opt &= ~OPT_n;
1784 #if BB_MMU /* NOMMU case backgrounded earlier */
1785                                 if (!(opt & OPT_f)) {
1786                                         client_background();
1787                                         /* do not background again! */
1788                                         opt = ((opt & ~OPT_b) | OPT_f);
1789                                 }
1790 #endif
1791                                 /* make future renew packets use different xid */
1792                                 /* xid = random_xid(); ...but why bother? */
1793
1794                                 continue; /* back to main loop */
1795                         }
1796                         if (*message == DHCPNAK) {
1797                                 /* If network has more than one DHCP server,
1798                                  * "wrong" server can reply first, with a NAK.
1799                                  * Do not interpret it as a NAK from "our" server.
1800                                  */
1801                                 if (server_addr != 0) {
1802                                         uint32_t svid;
1803                                         uint8_t *temp;
1804
1805                                         temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1806                                         if (!temp) {
1807  non_matching_svid:
1808                                                 log1("%s with wrong server ID, ignoring packet",
1809                                                         "Received DHCP NAK"
1810                                                 );
1811                                                 continue;
1812                                         }
1813                                         move_from_unaligned32(svid, temp);
1814                                         if (svid != server_addr)
1815                                                 goto non_matching_svid;
1816                                 }
1817                                 /* return to init state */
1818                                 bb_info_msg("Received DHCP NAK");
1819                                 udhcp_run_script(&packet, "nak");
1820                                 if (state != REQUESTING)
1821                                         udhcp_run_script(NULL, "deconfig");
1822                                 change_listen_mode(LISTEN_RAW);
1823                                 sleep(3); /* avoid excessive network traffic */
1824                                 state = INIT_SELECTING;
1825                                 client_config.first_secs = 0; /* make secs field count from 0 */
1826                                 requested_ip = 0;
1827                                 timeout = 0;
1828                                 packet_num = 0;
1829                                 already_waited_sec = 0;
1830                         }
1831                         continue;
1832                 /* case BOUND: - ignore all packets */
1833                 /* case RELEASED: - ignore all packets */
1834                 }
1835                 /* back to main loop */
1836         } /* for (;;) - main loop ends */
1837
1838  ret0:
1839         if (opt & OPT_R) /* release on quit */
1840                 perform_release(server_addr, requested_ip);
1841         retval = 0;
1842  ret:
1843         /*if (client_config.pidfile) - remove_pidfile has its own check */
1844                 remove_pidfile(client_config.pidfile);
1845         return retval;
1846 }