LXR busybox/networking/udhcp/common.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
   4 *
   5 * Licensed under GPLv2, see file LICENSE in this tarball for details.
   6 */
   7#include "common.h"
   8
   9#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
  10unsigned dhcp_verbose;
  11#endif
  12
  13const uint8_t MAC_BCAST_ADDR[6] ALIGN2 = {
  14        0xff, 0xff, 0xff, 0xff, 0xff, 0xff
  15};
  16
  17/* Supported options are easily added here.
  18 * See RFC2132 for more options.
  19 * OPTION_REQ: these options are requested by udhcpc (unless -o).
  20 */
  21const struct dhcp_optflag dhcp_optflags[] = {
  22        /* flags                                    code */
  23        { OPTION_IP                   | OPTION_REQ, 0x01 }, /* DHCP_SUBNET        */
  24        { OPTION_S32                              , 0x02 }, /* DHCP_TIME_OFFSET   */
  25        { OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x03 }, /* DHCP_ROUTER        */
  26//      { OPTION_IP | OPTION_LIST                 , 0x04 }, /* DHCP_TIME_SERVER   */
  27//      { OPTION_IP | OPTION_LIST                 , 0x05 }, /* DHCP_NAME_SERVER   */
  28        { OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x06 }, /* DHCP_DNS_SERVER    */
  29//      { OPTION_IP | OPTION_LIST                 , 0x07 }, /* DHCP_LOG_SERVER    */
  30//      { OPTION_IP | OPTION_LIST                 , 0x08 }, /* DHCP_COOKIE_SERVER */
  31        { OPTION_IP | OPTION_LIST                 , 0x09 }, /* DHCP_LPR_SERVER    */
  32        { OPTION_STRING               | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME     */
  33        { OPTION_U16                              , 0x0d }, /* DHCP_BOOT_SIZE     */
  34        { OPTION_STRING               | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME   */
  35        { OPTION_IP                               , 0x10 }, /* DHCP_SWAP_SERVER   */
  36        { OPTION_STRING                           , 0x11 }, /* DHCP_ROOT_PATH     */
  37        { OPTION_U8                               , 0x17 }, /* DHCP_IP_TTL        */
  38        { OPTION_U16                              , 0x1a }, /* DHCP_MTU           */
  39        { OPTION_IP                   | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST     */
  40        { OPTION_STRING                           , 0x28 }, /* DHCP_NIS_DOMAIN    */
  41        { OPTION_IP | OPTION_LIST                 , 0x29 }, /* DHCP_NIS_SERVER    */
  42        { OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x2a }, /* DHCP_NTP_SERVER    */
  43        { OPTION_IP | OPTION_LIST                 , 0x2c }, /* DHCP_WINS_SERVER   */
  44        { OPTION_U32                              , 0x33 }, /* DHCP_LEASE_TIME    */
  45        { OPTION_IP                               , 0x36 }, /* DHCP_SERVER_ID     */
  46        { OPTION_STRING                           , 0x38 }, /* DHCP_ERR_MESSAGE   */
  47//TODO: must be combined with 'sname' and 'file' handling:
  48        { OPTION_STRING                           , 0x42 }, /* DHCP_TFTP_SERVER_NAME */
  49        { OPTION_STRING                           , 0x43 }, /* DHCP_BOOT_FILE     */
  50//TODO: not a string, but a set of LASCII strings:
  51//      { OPTION_STRING                           , 0x4D }, /* DHCP_USER_CLASS    */
  52#if ENABLE_FEATURE_UDHCP_RFC3397
  53        { OPTION_DNS_STRING | OPTION_LIST         , 0x77 }, /* DHCP_DOMAIN_SEARCH */
  54        { OPTION_SIP_SERVERS                      , 0x78 }, /* DHCP_SIP_SERVERS   */
  55#endif
  56        { OPTION_STATIC_ROUTES                    , 0x79 }, /* DHCP_STATIC_ROUTES */
  57        { OPTION_STRING                           , 0xfc }, /* DHCP_WPAD          */
  58
  59        /* Options below have no match in dhcp_option_strings[],
  60         * are not passed to dhcpc scripts, and cannot be specified
  61         * with "option XXX YYY" syntax in dhcpd config file.
  62         * These entries are only used internally by udhcp[cd]
  63         * to correctly encode options into packets.
  64         */
  65
  66        { OPTION_IP                               , 0x32 }, /* DHCP_REQUESTED_IP  */
  67        { OPTION_U8                               , 0x35 }, /* DHCP_MESSAGE_TYPE  */
  68        { OPTION_U16                              , 0x39 }, /* DHCP_MAX_SIZE      */
  69        { OPTION_STRING                           , 0x3c }, /* DHCP_VENDOR        */
  70//FIXME: handling of this option is not exactly correct:
  71        { OPTION_STRING                           , 0x3d }, /* DHCP_CLIENT_ID     */
  72        { 0, 0 } /* zeroed terminating entry */
  73};
  74
  75/* Used for converting options from incoming packets to env variables
  76 * for udhcpc stript, and for setting options for udhcpd via
  77 * "opt OPTION_NAME OPTION_VALUE" directives in udhcpd.conf file.
  78 */
  79/* Must match dhcp_optflags[] order */
  80const char dhcp_option_strings[] ALIGN1 =
  81        "subnet" "\0"      /* DHCP_SUBNET         */
  82        "timezone" "\0"    /* DHCP_TIME_OFFSET    */
  83        "router" "\0"      /* DHCP_ROUTER         */
  84//      "timesrv" "\0"     /* DHCP_TIME_SERVER    */
  85//      "namesrv" "\0"     /* DHCP_NAME_SERVER    */
  86        "dns" "\0"         /* DHCP_DNS_SERVER     */
  87//      "logsrv" "\0"      /* DHCP_LOG_SERVER     */
  88//      "cookiesrv" "\0"   /* DHCP_COOKIE_SERVER  */
  89        "lprsrv" "\0"      /* DHCP_LPR_SERVER     */
  90        "hostname" "\0"    /* DHCP_HOST_NAME      */
  91        "bootsize" "\0"    /* DHCP_BOOT_SIZE      */
  92        "domain" "\0"      /* DHCP_DOMAIN_NAME    */
  93        "swapsrv" "\0"     /* DHCP_SWAP_SERVER    */
  94        "rootpath" "\0"    /* DHCP_ROOT_PATH      */
  95        "ipttl" "\0"       /* DHCP_IP_TTL         */
  96        "mtu" "\0"         /* DHCP_MTU            */
  97        "broadcast" "\0"   /* DHCP_BROADCAST      */
  98        "nisdomain" "\0"   /* DHCP_NIS_DOMAIN     */
  99        "nissrv" "\0"      /* DHCP_NIS_SERVER     */
 100        "ntpsrv" "\0"      /* DHCP_NTP_SERVER     */
 101        "wins" "\0"        /* DHCP_WINS_SERVER    */
 102        "lease" "\0"       /* DHCP_LEASE_TIME     */
 103        "serverid" "\0"    /* DHCP_SERVER_ID      */
 104        "message" "\0"     /* DHCP_ERR_MESSAGE    */
 105        "tftp" "\0"        /* DHCP_TFTP_SERVER_NAME */
 106        "bootfile" "\0"    /* DHCP_BOOT_FILE      */
 107//      "userclass" "\0"   /* DHCP_USER_CLASS     */
 108#if ENABLE_FEATURE_UDHCP_RFC3397
 109        "search" "\0"      /* DHCP_DOMAIN_SEARCH  */
 110// doesn't work in udhcpd.conf since OPTION_SIP_SERVERS
 111// is not handled yet by "string->option" conversion code:
 112        "sipsrv" "\0"      /* DHCP_SIP_SERVERS    */
 113#endif
 114// doesn't work in udhcpd.conf since OPTION_STATIC_ROUTES
 115// is not handled yet by "string->option" conversion code:
 116        "staticroutes" "\0"/* DHCP_STATIC_ROUTES  */
 117        "wpad" "\0"        /* DHCP_WPAD           */
 118        ;
 119
 120/* Lengths of the option types in binary form.
 121 * Used by:
 122 * udhcp_str2optset: to determine how many bytes to allocate.
 123 * xmalloc_optname_optval: to estimate string length
 124 * from binary option length: (option[LEN] / dhcp_option_lengths[opt_type])
 125 * is the number of elements, multiply in by one element's string width
 126 * (len_of_option_as_string[opt_type]) and you know how wide string you need.
 127 */
 128const uint8_t dhcp_option_lengths[] ALIGN1 = {
 129        [OPTION_IP] =      4,
 130        [OPTION_IP_PAIR] = 8,
 131//      [OPTION_BOOLEAN] = 1,
 132        [OPTION_STRING] =  1,  /* ignored by udhcp_str2optset */
 133#if ENABLE_FEATURE_UDHCP_RFC3397
 134        [OPTION_DNS_STRING] = 1,  /* ignored by both udhcp_str2optset and xmalloc_optname_optval */
 135        [OPTION_SIP_SERVERS] = 1,
 136#endif
 137        [OPTION_U8] =      1,
 138        [OPTION_U16] =     2,
 139//      [OPTION_S16] =     2,
 140        [OPTION_U32] =     4,
 141        [OPTION_S32] =     4,
 142        /* Just like OPTION_STRING, we use minimum length here */
 143        [OPTION_STATIC_ROUTES] = 5,
 144};
 145
 146
 147#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2
 148static void log_option(const char *pfx, const uint8_t *opt)
 149{
 150        if (dhcp_verbose >= 2) {
 151                char buf[256 * 2 + 2];
 152                *bin2hex(buf, (void*) (opt + OPT_DATA), opt[OPT_LEN]) = '\0';
 153                bb_info_msg("%s: 0x%02x %s", pfx, opt[OPT_CODE], buf);
 154        }
 155}
 156#else
 157# define log_option(pfx, opt) ((void)0)
 158#endif
 159
 160unsigned FAST_FUNC udhcp_option_idx(const char *name)
 161{
 162        int n = index_in_strings(dhcp_option_strings, name);
 163        if (n >= 0)
 164                return n;
 165
 166        {
 167                char buf[sizeof(dhcp_option_strings)];
 168                char *d = buf;
 169                const char *s = dhcp_option_strings;
 170                while (s < dhcp_option_strings + sizeof(dhcp_option_strings) - 2) {
 171                        *d++ = (*s == '\0' ? ' ' : *s);
 172                        s++;
 173                }
 174                *d = '\0';
 175                bb_error_msg_and_die("unknown option '%s', known options: %s", name, buf);
 176        }
 177}
 178
 179/* Get an option with bounds checking (warning, result is not aligned) */
 180uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code)
 181{
 182        uint8_t *optionptr;
 183        int len;
 184        int rem;
 185        int overload = 0;
 186        enum {
 187                FILE_FIELD101  = FILE_FIELD  * 0x101,
 188                SNAME_FIELD101 = SNAME_FIELD * 0x101,
 189        };
 190
 191        /* option bytes: [code][len][data1][data2]..[dataLEN] */
 192        optionptr = packet->options;
 193        rem = sizeof(packet->options);
 194        while (1) {
 195                if (rem <= 0) {
 196                        bb_error_msg("bad packet, malformed option field");
 197                        return NULL;
 198                }
 199                if (optionptr[OPT_CODE] == DHCP_PADDING) {
 200                        rem--;
 201                        optionptr++;
 202                        continue;
 203                }
 204                if (optionptr[OPT_CODE] == DHCP_END) {
 205                        if ((overload & FILE_FIELD101) == FILE_FIELD) {
 206                                /* can use packet->file, and didn't look at it yet */
 207                                overload |= FILE_FIELD101; /* "we looked at it" */
 208                                optionptr = packet->file;
 209                                rem = sizeof(packet->file);
 210                                continue;
 211                        }
 212                        if ((overload & SNAME_FIELD101) == SNAME_FIELD) {
 213                                /* can use packet->sname, and didn't look at it yet */
 214                                overload |= SNAME_FIELD101; /* "we looked at it" */
 215                                optionptr = packet->sname;
 216                                rem = sizeof(packet->sname);
 217                                continue;
 218                        }
 219                        break;
 220                }
 221                len = 2 + optionptr[OPT_LEN];
 222                rem -= len;
 223                if (rem < 0)
 224                        continue; /* complain and return NULL */
 225
 226                if (optionptr[OPT_CODE] == code) {
 227                        log_option("Option found", optionptr);
 228                        return optionptr + OPT_DATA;
 229                }
 230
 231                if (optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) {
 232                        overload |= optionptr[OPT_DATA];
 233                        /* fall through */
 234                }
 235                optionptr += len;
 236        }
 237
 238        /* log3 because udhcpc uses it a lot - very noisy */
 239        log3("Option 0x%02x not found", code);
 240        return NULL;
 241}
 242
 243/* Return the position of the 'end' option (no bounds checking) */
 244int FAST_FUNC udhcp_end_option(uint8_t *optionptr)
 245{
 246        int i = 0;
 247
 248        while (optionptr[i] != DHCP_END) {
 249                if (optionptr[i] != DHCP_PADDING)
 250                        i += optionptr[i + OPT_LEN] + OPT_DATA-1;
 251                i++;
 252        }
 253        return i;
 254}
 255
 256/* Add an option (supplied in binary form) to the options.
 257 * Option format: [code][len][data1][data2]..[dataLEN]
 258 */
 259void FAST_FUNC udhcp_add_binary_option(struct dhcp_packet *packet, uint8_t *addopt)
 260{
 261        unsigned len;
 262        uint8_t *optionptr = packet->options;
 263        unsigned end = udhcp_end_option(optionptr);
 264
 265        len = OPT_DATA + addopt[OPT_LEN];
 266        /* end position + (option code/length + addopt length) + end option */
 267        if (end + len + 1 >= DHCP_OPTIONS_BUFSIZE) {
 268//TODO: learn how to use overflow option if we exhaust packet->options[]
 269                bb_error_msg("option 0x%02x did not fit into the packet",
 270                                addopt[OPT_CODE]);
 271                return;
 272        }
 273        log_option("Adding option", addopt);
 274        memcpy(optionptr + end, addopt, len);
 275        optionptr[end + len] = DHCP_END;
 276}
 277
 278/* Add an one to four byte option to a packet */
 279void FAST_FUNC udhcp_add_simple_option(struct dhcp_packet *packet, uint8_t code, uint32_t data)
 280{
 281        const struct dhcp_optflag *dh;
 282
 283        for (dh = dhcp_optflags; dh->code; dh++) {
 284                if (dh->code == code) {
 285                        uint8_t option[6], len;
 286
 287                        option[OPT_CODE] = code;
 288                        len = dhcp_option_lengths[dh->flags & OPTION_TYPE_MASK];
 289                        option[OPT_LEN] = len;
 290                        if (BB_BIG_ENDIAN)
 291                                data <<= 8 * (4 - len);
 292                        /* Assignment is unaligned! */
 293                        move_to_unaligned32(&option[OPT_DATA], data);
 294                        udhcp_add_binary_option(packet, option);
 295                        return;
 296                }
 297        }
 298
 299        bb_error_msg("can't add option 0x%02x", code);
 300}
 301
 302/* Find option 'code' in opt_list */
 303struct option_set* FAST_FUNC udhcp_find_option(struct option_set *opt_list, uint8_t code)
 304{
 305        while (opt_list && opt_list->data[OPT_CODE] < code)
 306                opt_list = opt_list->next;
 307
 308        if (opt_list && opt_list->data[OPT_CODE] == code)
 309                return opt_list;
 310        return NULL;
 311}
 312
 313/* Parse string to IP in network order */
 314int FAST_FUNC udhcp_str2nip(const char *str, void *arg)
 315{
 316        len_and_sockaddr *lsa;
 317
 318        lsa = host_and_af2sockaddr(str, 0, AF_INET);
 319        if (!lsa)
 320                return 0;
 321        *(uint32_t*)arg = lsa->u.sin.sin_addr.s_addr;
 322        free(lsa);
 323        return 1;
 324}
 325
 326/* udhcp_str2optset:
 327 * Parse string option representation to binary form and add it to opt_list.
 328 * Called to parse "udhcpc -x OPTNAME:OPTVAL"
 329 * and to parse udhcpd.conf's "opt OPTNAME OPTVAL" directives.
 330 */
 331/* helper for the helper */
 332static char *allocate_tempopt_if_needed(
 333                const struct dhcp_optflag *optflag,
 334                char *buffer,
 335                int *length_p)
 336{
 337        char *allocated = NULL;
 338        if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_BIN) {
 339                const char *end;
 340                allocated = xstrdup(buffer); /* more than enough */
 341                end = hex2bin(allocated, buffer, 255);
 342                if (errno)
 343                        bb_error_msg_and_die("malformed hex string '%s'", buffer);
 344                *length_p = end - allocated;
 345        }
 346        return allocated;
 347}
 348/* helper: add an option to the opt_list */
 349static NOINLINE void attach_option(
 350                struct option_set **opt_list,
 351                const struct dhcp_optflag *optflag,
 352                char *buffer,
 353                int length)
 354{
 355        struct option_set *existing, *new, **curr;
 356        char *allocated = NULL;
 357
 358        existing = udhcp_find_option(*opt_list, optflag->code);
 359        if (!existing) {
 360                log2("Attaching option %02x to list", optflag->code);
 361                allocated = allocate_tempopt_if_needed(optflag, buffer, &length);
 362#if ENABLE_FEATURE_UDHCP_RFC3397
 363                if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_DNS_STRING) {
 364                        /* reuse buffer and length for RFC1035-formatted string */
 365                        allocated = buffer = (char *)dname_enc(NULL, 0, buffer, &length);
 366                }
 367#endif
 368                /* make a new option */
 369                new = xmalloc(sizeof(*new));
 370                new->data = xmalloc(length + OPT_DATA);
 371                new->data[OPT_CODE] = optflag->code;
 372                new->data[OPT_LEN] = length;
 373                memcpy(new->data + OPT_DATA, buffer, length);
 374
 375                curr = opt_list;
 376                while (*curr && (*curr)->data[OPT_CODE] < optflag->code)
 377                        curr = &(*curr)->next;
 378
 379                new->next = *curr;
 380                *curr = new;
 381                goto ret;
 382        }
 383
 384        if (optflag->flags & OPTION_LIST) {
 385                unsigned old_len;
 386
 387                /* add it to an existing option */
 388                log2("Attaching option %02x to existing member of list", optflag->code);
 389                allocated = allocate_tempopt_if_needed(optflag, buffer, &length);
 390                old_len = existing->data[OPT_LEN];
 391#if ENABLE_FEATURE_UDHCP_RFC3397
 392                if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_DNS_STRING) {
 393                        /* reuse buffer and length for RFC1035-formatted string */
 394                        allocated = buffer = (char *)dname_enc(existing->data + OPT_DATA, old_len, buffer, &length);
 395                }
 396#endif
 397                if (old_len + length < 255) {
 398                        /* actually 255 is ok too, but adding a space can overlow it */
 399
 400                        existing->data = xrealloc(existing->data, OPT_DATA + 1 + old_len + length);
 401                        if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING) {
 402                                /* add space separator between STRING options in a list */
 403                                existing->data[OPT_DATA + old_len] = ' ';
 404                                old_len++;
 405                        }
 406                        memcpy(existing->data + OPT_DATA + old_len, buffer, length);
 407                        existing->data[OPT_LEN] = old_len + length;
 408                } /* else, ignore the data, we could put this in a second option in the future */
 409        } /* else, ignore the new data */
 410
 411 ret:
 412        free(allocated);
 413}
 414
 415int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg)
 416{
 417        struct option_set **opt_list = arg;
 418        char *opt, *val, *endptr;
 419        char *str;
 420        const struct dhcp_optflag *optflag;
 421        struct dhcp_optflag bin_optflag;
 422        unsigned optcode;
 423        int retval, length;
 424        char buffer[8] ALIGNED(4);
 425        uint16_t *result_u16 = (uint16_t *) buffer;
 426        uint32_t *result_u32 = (uint32_t *) buffer;
 427
 428        /* Cheat, the only *const* str possible is "" */
 429        str = (char *) const_str;
 430        opt = strtok(str, " \t=");
 431        if (!opt)
 432                return 0;
 433
 434        optcode = bb_strtou(opt, NULL, 0);
 435        if (!errno && optcode < 255) {
 436                /* Raw (numeric) option code */
 437                bin_optflag.flags = OPTION_BIN;
 438                bin_optflag.code = optcode;
 439                optflag = &bin_optflag;
 440        } else {
 441                optflag = &dhcp_optflags[udhcp_option_idx(opt)];
 442        }
 443
 444        retval = 0;
 445        do {
 446                val = strtok(NULL, ", \t");
 447                if (!val)
 448                        break;
 449                length = dhcp_option_lengths[optflag->flags & OPTION_TYPE_MASK];
 450                retval = 0;
 451                opt = buffer; /* new meaning for variable opt */
 452                switch (optflag->flags & OPTION_TYPE_MASK) {
 453                case OPTION_IP:
 454                        retval = udhcp_str2nip(val, buffer);
 455                        break;
 456                case OPTION_IP_PAIR:
 457                        retval = udhcp_str2nip(val, buffer);
 458                        val = strtok(NULL, ", \t/-");
 459                        if (!val)
 460                                retval = 0;
 461                        if (retval)
 462                                retval = udhcp_str2nip(val, buffer + 4);
 463                        break;
 464                case OPTION_STRING:
 465#if ENABLE_FEATURE_UDHCP_RFC3397
 466                case OPTION_DNS_STRING:
 467#endif
 468                        length = strnlen(val, 254);
 469                        if (length > 0) {
 470                                opt = val;
 471                                retval = 1;
 472                        }
 473                        break;
 474//              case OPTION_BOOLEAN: {
 475//                      static const char no_yes[] ALIGN1 = "no\0yes\0";
 476//                      buffer[0] = retval = index_in_strings(no_yes, val);
 477//                      retval++; /* 0 - bad; 1: "no" 2: "yes" */
 478//                      break;
 479//              }
 480                case OPTION_U8:
 481                        buffer[0] = strtoul(val, &endptr, 0);
 482                        retval = (endptr[0] == '\0');
 483                        break;
 484                /* htonX are macros in older libc's, using temp var
 485                 * in code below for safety */
 486                /* TODO: use bb_strtoX? */
 487                case OPTION_U16: {
 488                        unsigned long tmp = strtoul(val, &endptr, 0);
 489                        *result_u16 = htons(tmp);
 490                        retval = (endptr[0] == '\0' /*&& tmp < 0x10000*/);
 491                        break;
 492                }
 493//              case OPTION_S16: {
 494//                      long tmp = strtol(val, &endptr, 0);
 495//                      *result_u16 = htons(tmp);
 496//                      retval = (endptr[0] == '\0');
 497//                      break;
 498//              }
 499                case OPTION_U32: {
 500                        unsigned long tmp = strtoul(val, &endptr, 0);
 501                        *result_u32 = htonl(tmp);
 502                        retval = (endptr[0] == '\0');
 503                        break;
 504                }
 505                case OPTION_S32: {
 506                        long tmp = strtol(val, &endptr, 0);
 507                        *result_u32 = htonl(tmp);
 508                        retval = (endptr[0] == '\0');
 509                        break;
 510                }
 511                case OPTION_BIN: /* handled in attach_option() */
 512                        opt = val;
 513                        retval = 1;
 514                default:
 515                        break;
 516                }
 517                if (retval)
 518                        attach_option(opt_list, optflag, opt, length);
 519        } while (retval && optflag->flags & OPTION_LIST);
 520
 521        return retval;
 522}
 523