resolv/ns_name.c

   1 /*
   2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (c) 1996,1999 by Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  15  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #include <sys/types.h>
  19
  20 #include <netinet/in.h>
  21 #include <arpa/nameser.h>
  22
  23 #include <errno.h>
  24 #include <resolv.h>
  25 #include <string.h>
  26 #include <ctype.h>
  27 #include <stdlib.h>
  28 #include <limits.h>
  29
  30 # define SPRINTF(x) ((size_t)sprintf x)
  31
  32 #define NS_TYPE_ELT                     0x40 /*%< EDNS0 extended label type */
  33 #define DNS_LABELTYPE_BITSTRING         0x41
  34
  35 /* Data. */
  36
  37 static const char       digits[] = "0123456789";
  38
  39 static const char digitvalue[256] = {
  40         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*16*/
  41         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*32*/
  42         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*48*/
  43          0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, /*64*/
  44         -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*80*/
  45         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*96*/
  46         -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*112*/
  47         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*128*/
  48         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  49         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  50         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  51         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  52         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  53         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  54         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  55         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*256*/
  56 };
  57
  58 /* Forward. */
  59
  60 static int              special(int);
  61 static int              printable(int);
  62 static int              dn_find(const u_char *, const u_char *,
  63                                 const u_char * const *,
  64                                 const u_char * const *);
  65 static int              encode_bitstring(const char **, const char *,
  66                                          unsigned char **, unsigned char **,
  67                                          unsigned const char *);
  68 static int              labellen(const u_char *);
  69 static int              decode_bitstring(const unsigned char **,
  70                                          char *, const char *);
  71
  72 /* Public. */
  73
  74 /*%
  75  *      Convert an encoded domain name to printable ascii as per RFC1035.
  76
  77  * return:
  78  *\li   Number of bytes written to buffer, or -1 (with errno set)
  79  *
  80  * notes:
  81  *\li   The root is returned as "."
  82  *\li   All other domains are returned in non absolute form
  83  */
  84 int
  85 ns_name_ntop(const u_char *src, char *dst, size_t dstsiz)
  86 {
  87         const u_char *cp;
  88         char *dn, *eom;
  89         u_char c;
  90         u_int n;
  91         int l;
  92
  93         cp = src;
  94         dn = dst;
  95         eom = dst + dstsiz;
  96
  97         while ((n = *cp++) != 0) {
  98                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
  99                         /* Some kind of compression pointer. */
 100                         __set_errno (EMSGSIZE);
 101                         return (-1);
 102                 }
 103                 if (dn != dst) {
 104                         if (dn >= eom) {
 105                                 __set_errno (EMSGSIZE);
 106                                 return (-1);
 107                         }
 108                         *dn++ = '.';
 109                 }
 110                 if ((l = labellen(cp - 1)) < 0) {
 111                         __set_errno (EMSGSIZE);
 112                         return(-1);
 113                 }
 114                 if (dn + l >= eom) {
 115                         __set_errno (EMSGSIZE);
 116                         return (-1);
 117                 }
 118                 if ((n & NS_CMPRSFLGS) == NS_TYPE_ELT) {
 119                         int m;
 120
 121                         if (n != DNS_LABELTYPE_BITSTRING) {
 122                                 /* XXX: labellen should reject this case */
 123                                 __set_errno (EINVAL);
 124                                 return(-1);
 125                         }
 126                         if ((m = decode_bitstring(&cp, dn, eom)) < 0)
 127                         {
 128                                 __set_errno (EMSGSIZE);
 129                                 return(-1);
 130                         }
 131                         dn += m;
 132                         continue;
 133                 }
 134                 for ((void)NULL; l > 0; l--) {
 135                         c = *cp++;
 136                         if (special(c)) {
 137                                 if (dn + 1 >= eom) {
 138                                         __set_errno (EMSGSIZE);
 139                                         return (-1);
 140                                 }
 141                                 *dn++ = '\\';
 142                                 *dn++ = (char)c;
 143                         } else if (!printable(c)) {
 144                                 if (dn + 3 >= eom) {
 145                                         __set_errno (EMSGSIZE);
 146                                         return (-1);
 147                                 }
 148                                 *dn++ = '\\';
 149                                 *dn++ = digits[c / 100];
 150                                 *dn++ = digits[(c % 100) / 10];
 151                                 *dn++ = digits[c % 10];
 152                         } else {
 153                                 if (dn >= eom) {
 154                                         __set_errno (EMSGSIZE);
 155                                         return (-1);
 156                                 }
 157                                 *dn++ = (char)c;
 158                         }
 159                 }
 160         }
 161         if (dn == dst) {
 162                 if (dn >= eom) {
 163                         __set_errno (EMSGSIZE);
 164                         return (-1);
 165                 }
 166                 *dn++ = '.';
 167         }
 168         if (dn >= eom) {
 169                 __set_errno (EMSGSIZE);
 170                 return (-1);
 171         }
 172         *dn++ = '\0';
 173         return (dn - dst);
 174 }
 175 libresolv_hidden_def (ns_name_ntop)
 176 strong_alias (ns_name_ntop, __ns_name_ntop)
 177
 178 /*%
 179  *      Convert an ascii string into an encoded domain name as per RFC1035.
 180  *
 181  * return:
 182  *
 183  *\li   -1 if it fails
 184  *\li   1 if string was fully qualified
 185  *\li   0 is string was not fully qualified
 186  *
 187  * notes:
 188  *\li   Enforces label and domain length limits.
 189  */
 190
 191 int
 192 ns_name_pton(const char *src, u_char *dst, size_t dstsiz)
 193 {
 194         u_char *label, *bp, *eom;
 195         int c, n, escaped, e = 0;
 196         char *cp;
 197
 198         escaped = 0;
 199         bp = dst;
 200         eom = dst + dstsiz;
 201         label = bp++;
 202
 203         while ((c = *src++) != 0) {
 204                 if (escaped) {
 205                         if (c == '[') { /*%< start a bit string label */
 206                                 if ((cp = strchr(src, ']')) == NULL) {
 207                                         __set_errno (EINVAL);
 208                                         return(-1);
 209                                 }
 210                                 if ((e = encode_bitstring(&src, cp + 2,
 211                                                           &label, &bp, eom))
 212                                     != 0) {
 213                                         __set_errno (e);
 214                                         return(-1);
 215                                 }
 216                                 escaped = 0;
 217                                 label = bp++;
 218                                 if ((c = *src++) == 0)
 219                                         goto done;
 220                                 else if (c != '.') {
 221                                         __set_errno (EINVAL);
 222                                         return(-1);
 223                                 }
 224                                 continue;
 225                         }
 226                         else if ((cp = strchr(digits, c)) != NULL) {
 227                                 n = (cp - digits) * 100;
 228                                 if ((c = *src++) == 0 ||
 229                                     (cp = strchr(digits, c)) == NULL) {
 230                                         __set_errno (EMSGSIZE);
 231                                         return (-1);
 232                                 }
 233                                 n += (cp - digits) * 10;
 234                                 if ((c = *src++) == 0 ||
 235                                     (cp = strchr(digits, c)) == NULL) {
 236                                         __set_errno (EMSGSIZE);
 237                                         return (-1);
 238                                 }
 239                                 n += (cp - digits);
 240                                 if (n > 255) {
 241                                         __set_errno (EMSGSIZE);
 242                                         return (-1);
 243                                 }
 244                                 c = n;
 245                         }
 246                         escaped = 0;
 247                 } else if (c == '\\') {
 248                         escaped = 1;
 249                         continue;
 250                 } else if (c == '.') {
 251                         c = (bp - label - 1);
 252                         if ((c & NS_CMPRSFLGS) != 0) {  /*%< Label too big. */
 253                                 __set_errno (EMSGSIZE);
 254                                 return (-1);
 255                         }
 256                         if (label >= eom) {
 257                                 __set_errno (EMSGSIZE);
 258                                 return (-1);
 259                         }
 260                         *label = c;
 261                         /* Fully qualified ? */
 262                         if (*src == '\0') {
 263                                 if (c != 0) {
 264                                         if (bp >= eom) {
 265                                                 __set_errno (EMSGSIZE);
 266                                                 return (-1);
 267                                         }
 268                                         *bp++ = '\0';
 269                                 }
 270                                 if ((bp - dst) > MAXCDNAME) {
 271                                         __set_errno (EMSGSIZE);
 272                                         return (-1);
 273                                 }
 274                                 return (1);
 275                         }
 276                         if (c == 0 || *src == '.') {
 277                                 __set_errno (EMSGSIZE);
 278                                 return (-1);
 279                         }
 280                         label = bp++;
 281                         continue;
 282                 }
 283                 if (bp >= eom) {
 284                         __set_errno (EMSGSIZE);
 285                         return (-1);
 286                 }
 287                 *bp++ = (u_char)c;
 288         }
 289         c = (bp - label - 1);
 290         if ((c & NS_CMPRSFLGS) != 0) {          /*%< Label too big. */
 291                 __set_errno (EMSGSIZE);
 292                 return (-1);
 293         }
 294   done:
 295         if (label >= eom) {
 296                 __set_errno (EMSGSIZE);
 297                 return (-1);
 298         }
 299         *label = c;
 300         if (c != 0) {
 301                 if (bp >= eom) {
 302                         __set_errno (EMSGSIZE);
 303                         return (-1);
 304                 }
 305                 *bp++ = 0;
 306         }
 307         if ((bp - dst) > MAXCDNAME) {   /*%< src too big */
 308                 __set_errno (EMSGSIZE);
 309                 return (-1);
 310         }
 311         return (0);
 312 }
 313 libresolv_hidden_def (ns_name_pton)
 314
 315 /*%
 316  *      Convert a network strings labels into all lowercase.
 317  *
 318  * return:
 319  *\li   Number of bytes written to buffer, or -1 (with errno set)
 320  *
 321  * notes:
 322  *\li   Enforces label and domain length limits.
 323  */
 324
 325 int
 326 ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz)
 327 {
 328         const u_char *cp;
 329         u_char *dn, *eom;
 330         u_char c;
 331         u_int n;
 332         int l;
 333
 334         cp = src;
 335         dn = dst;
 336         eom = dst + dstsiz;
 337
 338         if (dn >= eom) {
 339                 __set_errno (EMSGSIZE);
 340                 return (-1);
 341         }
 342         while ((n = *cp++) != 0) {
 343                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 344                         /* Some kind of compression pointer. */
 345                         __set_errno (EMSGSIZE);
 346                         return (-1);
 347                 }
 348                 *dn++ = n;
 349                 if ((l = labellen(cp - 1)) < 0) {
 350                         __set_errno (EMSGSIZE);
 351                         return (-1);
 352                 }
 353                 if (dn + l >= eom) {
 354                         __set_errno (EMSGSIZE);
 355                         return (-1);
 356                 }
 357                 for ((void)NULL; l > 0; l--) {
 358                         c = *cp++;
 359                         if (isupper(c))
 360                                 *dn++ = tolower(c);
 361                         else
 362                                 *dn++ = c;
 363                 }
 364         }
 365         *dn++ = '\0';
 366         return (dn - dst);
 367 }
 368
 369 /*%
 370  *      Unpack a domain name from a message, source may be compressed.
 371  *
 372  * return:
 373  *\li   -1 if it fails, or consumed octets if it succeeds.
 374  */
 375 int
 376 ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
 377                u_char *dst, size_t dstsiz)
 378 {
 379         const u_char *srcp, *dstlim;
 380         u_char *dstp;
 381         int n, len, checked, l;
 382
 383         len = -1;
 384         checked = 0;
 385         dstp = dst;
 386         srcp = src;
 387         dstlim = dst + dstsiz;
 388         if (srcp < msg || srcp >= eom) {
 389                 __set_errno (EMSGSIZE);
 390                 return (-1);
 391         }
 392         /* Fetch next label in domain name. */
 393         while ((n = *srcp++) != 0) {
 394                 /* Check for indirection. */
 395                 switch (n & NS_CMPRSFLGS) {
 396                 case 0:
 397                 case NS_TYPE_ELT:
 398                         /* Limit checks. */
 399                         if ((l = labellen(srcp - 1)) < 0) {
 400                                 __set_errno (EMSGSIZE);
 401                                 return(-1);
 402                         }
 403                         if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
 404                                 __set_errno (EMSGSIZE);
 405                                 return (-1);
 406                         }
 407                         checked += l + 1;
 408                         *dstp++ = n;
 409                         memcpy(dstp, srcp, l);
 410                         dstp += l;
 411                         srcp += l;
 412                         break;
 413
 414                 case NS_CMPRSFLGS:
 415                         if (srcp >= eom) {
 416                                 __set_errno (EMSGSIZE);
 417                                 return (-1);
 418                         }
 419                         if (len < 0)
 420                                 len = srcp - src + 1;
 421                         srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
 422                         if (srcp < msg || srcp >= eom) {  /*%< Out of range. */
 423                                 __set_errno (EMSGSIZE);
 424                                 return (-1);
 425                         }
 426                         checked += 2;
 427                         /*
 428                          * Check for loops in the compressed name;
 429                          * if we've looked at the whole message,
 430                          * there must be a loop.
 431                          */
 432                         if (checked >= eom - msg) {
 433                                 __set_errno (EMSGSIZE);
 434                                 return (-1);
 435                         }
 436                         break;
 437
 438                 default:
 439                         __set_errno (EMSGSIZE);
 440                         return (-1);                    /*%< flag error */
 441                 }
 442         }
 443         *dstp = '\0';
 444         if (len < 0)
 445                 len = srcp - src;
 446         return (len);
 447 }
 448 libresolv_hidden_def (ns_name_unpack)
 449 strong_alias (ns_name_unpack, __ns_name_unpack)
 450
 451 /*%
 452  *      Pack domain name 'domain' into 'comp_dn'.
 453  *
 454  * return:
 455  *\li   Size of the compressed name, or -1.
 456  *
 457  * notes:
 458  *\li   'dnptrs' is an array of pointers to previous compressed names.
 459  *\li   dnptrs[0] is a pointer to the beginning of the message. The array
 460  *      ends with NULL.
 461  *\li   'lastdnptr' is a pointer to the end of the array pointed to
 462  *      by 'dnptrs'.
 463  *
 464  * Side effects:
 465  *\li   The list of pointers in dnptrs is updated for labels inserted into
 466  *      the message as we compress the name.  If 'dnptr' is NULL, we don't
 467  *      try to compress names. If 'lastdnptr' is NULL, we don't update the
 468  *      list.
 469  */
 470 int
 471 ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
 472              const u_char **dnptrs, const u_char **lastdnptr)
 473 {
 474         u_char *dstp;
 475         const u_char **cpp, **lpp, *eob, *msg;
 476         const u_char *srcp;
 477         int n, l, first = 1;
 478
 479         srcp = src;
 480         dstp = dst;
 481         eob = dstp + dstsiz;
 482         lpp = cpp = NULL;
 483         if (dnptrs != NULL) {
 484                 if ((msg = *dnptrs++) != NULL) {
 485                         for (cpp = dnptrs; *cpp != NULL; cpp++)
 486                                 (void)NULL;
 487                         lpp = cpp;      /*%< end of list to search */
 488                 }
 489         } else
 490                 msg = NULL;
 491
 492         /* make sure the domain we are about to add is legal */
 493         l = 0;
 494         do {
 495                 int l0;
 496
 497                 n = *srcp;
 498                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 499                         __set_errno (EMSGSIZE);
 500                         return (-1);
 501                 }
 502                 if ((l0 = labellen(srcp)) < 0) {
 503                         __set_errno (EINVAL);
 504                         return(-1);
 505                 }
 506                 l += l0 + 1;
 507                 if (l > MAXCDNAME) {
 508                         __set_errno (EMSGSIZE);
 509                         return (-1);
 510                 }
 511                 srcp += l0 + 1;
 512         } while (n != 0);
 513
 514         /* from here on we need to reset compression pointer array on error */
 515         srcp = src;
 516         do {
 517                 /* Look to see if we can use pointers. */
 518                 n = *srcp;
 519                 if (n != 0 && msg != NULL) {
 520                         l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
 521                                     (const u_char * const *)lpp);
 522                         if (l >= 0) {
 523                                 if (dstp + 1 >= eob) {
 524                                         goto cleanup;
 525                                 }
 526                                 *dstp++ = (l >> 8) | NS_CMPRSFLGS;
 527                                 *dstp++ = l % 256;
 528                                 return (dstp - dst);
 529                         }
 530                         /* Not found, save it. */
 531                         if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
 532                             (dstp - msg) < 0x4000 && first) {
 533                                 *cpp++ = dstp;
 534                                 *cpp = NULL;
 535                                 first = 0;
 536                         }
 537                 }
 538                 /* copy label to buffer */
 539                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 540                         /* Should not happen. */
 541                         goto cleanup;
 542                 }
 543                 n = labellen(srcp);
 544                 if (dstp + 1 + n >= eob) {
 545                         goto cleanup;
 546                 }
 547                 memcpy(dstp, srcp, n + 1);
 548                 srcp += n + 1;
 549                 dstp += n + 1;
 550         } while (n != 0);
 551
 552         if (dstp > eob) {
 553 cleanup:
 554                 if (msg != NULL)
 555                         *lpp = NULL;
 556                 __set_errno (EMSGSIZE);
 557                 return (-1);
 558         }
 559         return (dstp - dst);
 560 }
 561 libresolv_hidden_def (ns_name_pack)
 562
 563 /*%
 564  *      Expand compressed domain name to presentation format.
 565  *
 566  * return:
 567  *\li   Number of bytes read out of `src', or -1 (with errno set).
 568  *
 569  * note:
 570  *\li   Root domain returns as "." not "".
 571  */
 572 int
 573 ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
 574                    char *dst, size_t dstsiz)
 575 {
 576         u_char tmp[NS_MAXCDNAME];
 577         int n;
 578
 579         if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
 580                 return (-1);
 581         if (ns_name_ntop(tmp, dst, dstsiz) == -1)
 582                 return (-1);
 583         return (n);
 584 }
 585 libresolv_hidden_def (ns_name_uncompress)
 586
 587 /*%
 588  *      Compress a domain name into wire format, using compression pointers.
 589  *
 590  * return:
 591  *\li   Number of bytes consumed in `dst' or -1 (with errno set).
 592  *
 593  * notes:
 594  *\li   'dnptrs' is an array of pointers to previous compressed names.
 595  *\li   dnptrs[0] is a pointer to the beginning of the message.
 596  *\li   The list ends with NULL.  'lastdnptr' is a pointer to the end of the
 597  *      array pointed to by 'dnptrs'. Side effect is to update the list of
 598  *      pointers for labels inserted into the message as we compress the name.
 599  *\li   If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
 600  *      is NULL, we don't update the list.
 601  */
 602 int
 603 ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
 604                  const u_char **dnptrs, const u_char **lastdnptr)
 605 {
 606         u_char tmp[NS_MAXCDNAME];
 607
 608         if (ns_name_pton(src, tmp, sizeof tmp) == -1)
 609                 return (-1);
 610         return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
 611 }
 612 libresolv_hidden_def (ns_name_compress)
 613
 614 /*%
 615  * Reset dnptrs so that there are no active references to pointers at or
 616  * after src.
 617  */
 618 void
 619 ns_name_rollback(const u_char *src, const u_char **dnptrs,
 620                  const u_char **lastdnptr)
 621 {
 622         while (dnptrs < lastdnptr && *dnptrs != NULL) {
 623                 if (*dnptrs >= src) {
 624                         *dnptrs = NULL;
 625                         break;
 626                 }
 627                 dnptrs++;
 628         }
 629 }
 630
 631 /*%
 632  *      Advance *ptrptr to skip over the compressed name it points at.
 633  *
 634  * return:
 635  *\li   0 on success, -1 (with errno set) on failure.
 636  */
 637 int
 638 ns_name_skip(const u_char **ptrptr, const u_char *eom)
 639 {
 640         const u_char *cp;
 641         u_int n;
 642         int l;
 643
 644         cp = *ptrptr;
 645         while (cp < eom && (n = *cp++) != 0) {
 646                 /* Check for indirection. */
 647                 switch (n & NS_CMPRSFLGS) {
 648                 case 0:                 /*%< normal case, n == len */
 649                         cp += n;
 650                         continue;
 651                 case NS_TYPE_ELT: /*%< EDNS0 extended label */
 652                         if ((l = labellen(cp - 1)) < 0) {
 653                                 __set_errno (EMSGSIZE);
 654                                 return(-1);
 655                         }
 656                         cp += l;
 657                         continue;
 658                 case NS_CMPRSFLGS:      /*%< indirection */
 659                         cp++;
 660                         break;
 661                 default:                /*%< illegal type */
 662                         __set_errno (EMSGSIZE);
 663                         return (-1);
 664                 }
 665                 break;
 666         }
 667         if (cp > eom) {
 668                 __set_errno (EMSGSIZE);
 669                 return (-1);
 670         }
 671         *ptrptr = cp;
 672         return (0);
 673 }
 674 libresolv_hidden_def (ns_name_skip)
 675
 676 /* Private. */
 677
 678 /*%
 679  *      Thinking in noninternationalized USASCII (per the DNS spec),
 680  *      is this character special ("in need of quoting") ?
 681  *
 682  * return:
 683  *\li   boolean.
 684  */
 685 static int
 686 special(int ch) {
 687         switch (ch) {
 688         case 0x22: /*%< '"' */
 689         case 0x2E: /*%< '.' */
 690         case 0x3B: /*%< ';' */
 691         case 0x5C: /*%< '\\' */
 692         case 0x28: /*%< '(' */
 693         case 0x29: /*%< ')' */
 694         /* Special modifiers in zone files. */
 695         case 0x40: /*%< '@' */
 696         case 0x24: /*%< '$' */
 697                 return (1);
 698         default:
 699                 return (0);
 700         }
 701 }
 702
 703 /*%
 704  *      Thinking in noninternationalized USASCII (per the DNS spec),
 705  *      is this character visible and not a space when printed ?
 706  *
 707  * return:
 708  *\li   boolean.
 709  */
 710 static int
 711 printable(int ch) {
 712         return (ch > 0x20 && ch < 0x7f);
 713 }
 714
 715 /*%
 716  *      Thinking in noninternationalized USASCII (per the DNS spec),
 717  *      convert this character to lower case if it's upper case.
 718  */
 719 static int
 720 mklower(int ch) {
 721         if (ch >= 0x41 && ch <= 0x5A)
 722                 return (ch + 0x20);
 723         return (ch);
 724 }
 725
 726 /*%
 727  *      Search for the counted-label name in an array of compressed names.
 728  *
 729  * return:
 730  *\li   offset from msg if found, or -1.
 731  *
 732  * notes:
 733  *\li   dnptrs is the pointer to the first name on the list,
 734  *\li   not the pointer to the start of the message.
 735  */
 736 static int
 737 dn_find(const u_char *domain, const u_char *msg,
 738         const u_char * const *dnptrs,
 739         const u_char * const *lastdnptr)
 740 {
 741         const u_char *dn, *cp, *sp;
 742         const u_char * const *cpp;
 743         u_int n;
 744
 745         for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
 746                 sp = *cpp;
 747                 /*
 748                  * terminate search on:
 749                  * root label
 750                  * compression pointer
 751                  * unusable offset
 752                  */
 753                 while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
 754                        (sp - msg) < 0x4000) {
 755                         dn = domain;
 756                         cp = sp;
 757                         while ((n = *cp++) != 0) {
 758                                 /*
 759                                  * check for indirection
 760                                  */
 761                                 switch (n & NS_CMPRSFLGS) {
 762                                 case 0:         /*%< normal case, n == len */
 763                                         n = labellen(cp - 1); /*%< XXX */
 764                                         if (n != *dn++)
 765                                                 goto next;
 766
 767                                         for ((void)NULL; n > 0; n--)
 768                                                 if (mklower(*dn++) !=
 769                                                     mklower(*cp++))
 770                                                         goto next;
 771                                         /* Is next root for both ? */
 772                                         if (*dn == '\0' && *cp == '\0')
 773                                                 return (sp - msg);
 774                                         if (*dn)
 775                                                 continue;
 776                                         goto next;
 777                                 case NS_CMPRSFLGS:      /*%< indirection */
 778                                         cp = msg + (((n & 0x3f) << 8) | *cp);
 779                                         break;
 780
 781                                 default:        /*%< illegal type */
 782                                         __set_errno (EMSGSIZE);
 783                                         return (-1);
 784                                 }
 785                         }
 786   next: ;
 787                         sp += *sp + 1;
 788                 }
 789         }
 790         __set_errno (ENOENT);
 791         return (-1);
 792 }
 793
 794 static int
 795 decode_bitstring(const unsigned char **cpp, char *dn, const char *eom)
 796 {
 797         const unsigned char *cp = *cpp;
 798         char *beg = dn, tc;
 799         int b, blen, plen, i;
 800
 801         if ((blen = (*cp & 0xff)) == 0)
 802                 blen = 256;
 803         plen = (blen + 3) / 4;
 804         plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
 805         if (dn + plen >= eom)
 806                 return(-1);
 807
 808         cp++;
 809         i = SPRINTF((dn, "\\[x"));
 810         if (i < 0)
 811                 return (-1);
 812         dn += i;
 813         for (b = blen; b > 7; b -= 8, cp++) {
 814                 i = SPRINTF((dn, "%02x", *cp & 0xff));
 815                 if (i < 0)
 816                         return (-1);
 817                 dn += i;
 818         }
 819         if (b > 4) {
 820                 tc = *cp++;
 821                 i = SPRINTF((dn, "%02x", tc & (0xff << (8 - b))));
 822                 if (i < 0)
 823                         return (-1);
 824                 dn += i;
 825         } else if (b > 0) {
 826                 tc = *cp++;
 827                 i = SPRINTF((dn, "%1x",
 828                                ((tc >> 4) & 0x0f) & (0x0f << (4 - b))));
 829                 if (i < 0)
 830                         return (-1);
 831                 dn += i;
 832         }
 833         i = SPRINTF((dn, "/%d]", blen));
 834         if (i < 0)
 835                 return (-1);
 836         dn += i;
 837
 838         *cpp = cp;
 839         return(dn - beg);
 840 }
 841
 842 static int
 843 encode_bitstring(const char **bp, const char *end, unsigned char **labelp,
 844                  unsigned char ** dst, unsigned const char *eom)
 845 {
 846         int afterslash = 0;
 847         const char *cp = *bp;
 848         unsigned char *tp;
 849         char c;
 850         const char *beg_blen;
 851         char *end_blen = NULL;
 852         int value = 0, count = 0, tbcount = 0, blen = 0;
 853
 854         beg_blen = end_blen = NULL;
 855
 856         /* a bitstring must contain at least 2 characters */
 857         if (end - cp < 2)
 858                 return(EINVAL);
 859
 860         /* XXX: currently, only hex strings are supported */
 861         if (*cp++ != 'x')
 862                 return(EINVAL);
 863         if (!isxdigit((*cp) & 0xff)) /*%< reject '\[x/BLEN]' */
 864                 return(EINVAL);
 865
 866         for (tp = *dst + 1; cp < end && tp < eom; cp++) {
 867                 switch((c = *cp)) {
 868                 case ']':       /*%< end of the bitstring */
 869                         if (afterslash) {
 870                                 if (beg_blen == NULL)
 871                                         return(EINVAL);
 872                                 blen = (int)strtol(beg_blen, &end_blen, 10);
 873                                 if (*end_blen != ']')
 874                                         return(EINVAL);
 875                         }
 876                         if (count)
 877                                 *tp++ = ((value << 4) & 0xff);
 878                         cp++;   /*%< skip ']' */
 879                         goto done;
 880                 case '/':
 881                         afterslash = 1;
 882                         break;
 883                 default:
 884                         if (afterslash) {
 885                                 if (!isdigit(c&0xff))
 886                                         return(EINVAL);
 887                                 if (beg_blen == NULL) {
 888
 889                                         if (c == '0') {
 890                                                 /* blen never begings with 0 */
 891                                                 return(EINVAL);
 892                                         }
 893                                         beg_blen = cp;
 894                                 }
 895                         } else {
 896                                 if (!isxdigit(c&0xff))
 897                                         return(EINVAL);
 898                                 value <<= 4;
 899                                 value += digitvalue[(int)c];
 900                                 count += 4;
 901                                 tbcount += 4;
 902                                 if (tbcount > 256)
 903                                         return(EINVAL);
 904                                 if (count == 8) {
 905                                         *tp++ = value;
 906                                         count = 0;
 907                                 }
 908                         }
 909                         break;
 910                 }
 911         }
 912   done:
 913         if (cp >= end || tp >= eom)
 914                 return(EMSGSIZE);
 915
 916         /*
 917          * bit length validation:
 918          * If a <length> is present, the number of digits in the <bit-data>
 919          * MUST be just sufficient to contain the number of bits specified
 920          * by the <length>. If there are insignificant bits in a final
 921          * hexadecimal or octal digit, they MUST be zero.
 922          * RFC2673, Section 3.2.
 923          */
 924         if (blen > 0) {
 925                 int traillen;
 926
 927                 if (((blen + 3) & ~3) != tbcount)
 928                         return(EINVAL);
 929                 traillen = tbcount - blen; /*%< between 0 and 3 */
 930                 if (((value << (8 - traillen)) & 0xff) != 0)
 931                         return(EINVAL);
 932         }
 933         else
 934                 blen = tbcount;
 935         if (blen == 256)
 936                 blen = 0;
 937
 938         /* encode the type and the significant bit fields */
 939         **labelp = DNS_LABELTYPE_BITSTRING;
 940         **dst = blen;
 941
 942         *bp = cp;
 943         *dst = tp;
 944
 945         return(0);
 946 }
 947
 948 static int
 949 labellen(const u_char *lp)
 950 {
 951         int bitlen;
 952         u_char l = *lp;
 953
 954         if ((l & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 955                 /* should be avoided by the caller */
 956                 return(-1);
 957         }
 958
 959         if ((l & NS_CMPRSFLGS) == NS_TYPE_ELT) {
 960                 if (l == DNS_LABELTYPE_BITSTRING) {
 961                         if ((bitlen = *(lp + 1)) == 0)
 962                                 bitlen = 256;
 963                         return((bitlen + 7 ) / 8 + 1);
 964                 }
 965                 return(-1);     /*%< unknwon ELT */
 966         }
 967         return(l);
 968 }
 969
 970 /*! \file */