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 #if !defined(_LIBC) && !defined(lint)
  19 static const char rcsid[] = "$BINDId: ns_name.c,v 8.15 2000/03/30 22:53:46 vixie Exp $";
  20 #endif
  21
  22 #include <sys/types.h>
  23
  24 #include <netinet/in.h>
  25 #include <arpa/nameser.h>
  26
  27 #include <errno.h>
  28 #include <resolv.h>
  29 #include <string.h>
  30 #include <ctype.h>
  31 #include <stdlib.h>
  32 #include <limits.h>
  33
  34 # define SPRINTF(x) ((size_t)sprintf x)
  35
  36 #define NS_TYPE_ELT                     0x40 /*%< EDNS0 extended label type */
  37 #define DNS_LABELTYPE_BITSTRING         0x41
  38
  39 /* Data. */
  40
  41 static const char       digits[] = "0123456789";
  42
  43 static const char digitvalue[256] = {
  44         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*16*/
  45         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*32*/
  46         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*48*/
  47          0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, /*64*/
  48         -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*80*/
  49         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*96*/
  50         -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*112*/
  51         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*128*/
  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,
  56         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  57         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  58         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  59         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*256*/
  60 };
  61
  62 /* Forward. */
  63
  64 static int              special(int);
  65 static int              printable(int);
  66 static int              dn_find(const u_char *, const u_char *,
  67                                 const u_char * const *,
  68                                 const u_char * const *);
  69 static int              encode_bitstring(const char **, const char *,
  70                                          unsigned char **, unsigned char **,
  71                                          unsigned const char *);
  72 static int              labellen(const u_char *);
  73 static int              decode_bitstring(const unsigned char **,
  74                                          char *, const char *);
  75
  76 /* Public. */
  77
  78 /*%
  79  *      Convert an encoded domain name to printable ascii as per RFC1035.
  80
  81  * return:
  82  *\li   Number of bytes written to buffer, or -1 (with errno set)
  83  *
  84  * notes:
  85  *\li   The root is returned as "."
  86  *\li   All other domains are returned in non absolute form
  87  */
  88 int
  89 ns_name_ntop(const u_char *src, char *dst, size_t dstsiz)
  90 {
  91         const u_char *cp;
  92         char *dn, *eom;
  93         u_char c;
  94         u_int n;
  95         int l;
  96
  97         cp = src;
  98         dn = dst;
  99         eom = dst + dstsiz;
 100
 101         while ((n = *cp++) != 0) {
 102                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 103                         /* Some kind of compression pointer. */
 104                         __set_errno (EMSGSIZE);
 105                         return (-1);
 106                 }
 107                 if (dn != dst) {
 108                         if (dn >= eom) {
 109                                 __set_errno (EMSGSIZE);
 110                                 return (-1);
 111                         }
 112                         *dn++ = '.';
 113                 }
 114                 if ((l = labellen(cp - 1)) < 0) {
 115                         __set_errno (EMSGSIZE);
 116                         return(-1);
 117                 }
 118                 if (dn + l >= eom) {
 119                         __set_errno (EMSGSIZE);
 120                         return (-1);
 121                 }
 122                 if ((n & NS_CMPRSFLGS) == NS_TYPE_ELT) {
 123                         int m;
 124
 125                         if (n != DNS_LABELTYPE_BITSTRING) {
 126                                 /* XXX: labellen should reject this case */
 127                                 __set_errno (EINVAL);
 128                                 return(-1);
 129                         }
 130                         if ((m = decode_bitstring(&cp, dn, eom)) < 0)
 131                         {
 132                                 __set_errno (EMSGSIZE);
 133                                 return(-1);
 134                         }
 135                         dn += m;
 136                         continue;
 137                 }
 138                 for ((void)NULL; l > 0; l--) {
 139                         c = *cp++;
 140                         if (special(c)) {
 141                                 if (dn + 1 >= eom) {
 142                                         __set_errno (EMSGSIZE);
 143                                         return (-1);
 144                                 }
 145                                 *dn++ = '\\';
 146                                 *dn++ = (char)c;
 147                         } else if (!printable(c)) {
 148                                 if (dn + 3 >= eom) {
 149                                         __set_errno (EMSGSIZE);
 150                                         return (-1);
 151                                 }
 152                                 *dn++ = '\\';
 153                                 *dn++ = digits[c / 100];
 154                                 *dn++ = digits[(c % 100) / 10];
 155                                 *dn++ = digits[c % 10];
 156                         } else {
 157                                 if (dn >= eom) {
 158                                         __set_errno (EMSGSIZE);
 159                                         return (-1);
 160                                 }
 161                                 *dn++ = (char)c;
 162                         }
 163                 }
 164         }
 165         if (dn == dst) {
 166                 if (dn >= eom) {
 167                         __set_errno (EMSGSIZE);
 168                         return (-1);
 169                 }
 170                 *dn++ = '.';
 171         }
 172         if (dn >= eom) {
 173                 __set_errno (EMSGSIZE);
 174                 return (-1);
 175         }
 176         *dn++ = '\0';
 177         return (dn - dst);
 178 }
 179 libresolv_hidden_def (ns_name_ntop)
 180 strong_alias (ns_name_ntop, __ns_name_ntop)
 181
 182 /*%
 183  *      Convert a ascii string into an encoded domain name as per RFC1035.
 184  *
 185  * return:
 186  *
 187  *\li   -1 if it fails
 188  *\li   1 if string was fully qualified
 189  *\li   0 is string was not fully qualified
 190  *
 191  * notes:
 192  *\li   Enforces label and domain length limits.
 193  */
 194
 195 int
 196 ns_name_pton(const char *src, u_char *dst, size_t dstsiz)
 197 {
 198         u_char *label, *bp, *eom;
 199         int c, n, escaped, e = 0;
 200         char *cp;
 201
 202         escaped = 0;
 203         bp = dst;
 204         eom = dst + dstsiz;
 205         label = bp++;
 206
 207         while ((c = *src++) != 0) {
 208                 if (escaped) {
 209                         if (c == '[') { /*%< start a bit string label */
 210                                 if ((cp = strchr(src, ']')) == NULL) {
 211                                         __set_errno (EINVAL);
 212                                         return(-1);
 213                                 }
 214                                 if ((e = encode_bitstring(&src, cp + 2,
 215                                                           &label, &bp, eom))
 216                                     != 0) {
 217                                         __set_errno (e);
 218                                         return(-1);
 219                                 }
 220                                 escaped = 0;
 221                                 label = bp++;
 222                                 if ((c = *src++) == 0)
 223                                         goto done;
 224                                 else if (c != '.') {
 225                                         __set_errno (EINVAL);
 226                                         return(-1);
 227                                 }
 228                                 continue;
 229                         }
 230                         else if ((cp = strchr(digits, c)) != NULL) {
 231                                 n = (cp - digits) * 100;
 232                                 if ((c = *src++) == 0 ||
 233                                     (cp = strchr(digits, c)) == NULL) {
 234                                         __set_errno (EMSGSIZE);
 235                                         return (-1);
 236                                 }
 237                                 n += (cp - digits) * 10;
 238                                 if ((c = *src++) == 0 ||
 239                                     (cp = strchr(digits, c)) == NULL) {
 240                                         __set_errno (EMSGSIZE);
 241                                         return (-1);
 242                                 }
 243                                 n += (cp - digits);
 244                                 if (n > 255) {
 245                                         __set_errno (EMSGSIZE);
 246                                         return (-1);
 247                                 }
 248                                 c = n;
 249                         }
 250                         escaped = 0;
 251                 } else if (c == '\\') {
 252                         escaped = 1;
 253                         continue;
 254                 } else if (c == '.') {
 255                         c = (bp - label - 1);
 256                         if ((c & NS_CMPRSFLGS) != 0) {  /*%< Label too big. */
 257                                 __set_errno (EMSGSIZE);
 258                                 return (-1);
 259                         }
 260                         if (label >= eom) {
 261                                 __set_errno (EMSGSIZE);
 262                                 return (-1);
 263                         }
 264                         *label = c;
 265                         /* Fully qualified ? */
 266                         if (*src == '\0') {
 267                                 if (c != 0) {
 268                                         if (bp >= eom) {
 269                                                 __set_errno (EMSGSIZE);
 270                                                 return (-1);
 271                                         }
 272                                         *bp++ = '\0';
 273                                 }
 274                                 if ((bp - dst) > MAXCDNAME) {
 275                                         __set_errno (EMSGSIZE);
 276                                         return (-1);
 277                                 }
 278                                 return (1);
 279                         }
 280                         if (c == 0 || *src == '.') {
 281                                 __set_errno (EMSGSIZE);
 282                                 return (-1);
 283                         }
 284                         label = bp++;
 285                         continue;
 286                 }
 287                 if (bp >= eom) {
 288                         __set_errno (EMSGSIZE);
 289                         return (-1);
 290                 }
 291                 *bp++ = (u_char)c;
 292         }
 293         c = (bp - label - 1);
 294         if ((c & NS_CMPRSFLGS) != 0) {          /*%< Label too big. */
 295                 __set_errno (EMSGSIZE);
 296                 return (-1);
 297         }
 298   done:
 299         if (label >= eom) {
 300                 __set_errno (EMSGSIZE);
 301                 return (-1);
 302         }
 303         *label = c;
 304         if (c != 0) {
 305                 if (bp >= eom) {
 306                         __set_errno (EMSGSIZE);
 307                         return (-1);
 308                 }
 309                 *bp++ = 0;
 310         }
 311         if ((bp - dst) > MAXCDNAME) {   /*%< src too big */
 312                 __set_errno (EMSGSIZE);
 313                 return (-1);
 314         }
 315         return (0);
 316 }
 317 libresolv_hidden_def (ns_name_pton)
 318
 319 /*%
 320  *      Convert a network strings labels into all lowercase.
 321  *
 322  * return:
 323  *\li   Number of bytes written to buffer, or -1 (with errno set)
 324  *
 325  * notes:
 326  *\li   Enforces label and domain length limits.
 327  */
 328
 329 int
 330 ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz)
 331 {
 332         const u_char *cp;
 333         u_char *dn, *eom;
 334         u_char c;
 335         u_int n;
 336         int l;
 337
 338         cp = src;
 339         dn = dst;
 340         eom = dst + dstsiz;
 341
 342         if (dn >= eom) {
 343                 __set_errno (EMSGSIZE);
 344                 return (-1);
 345         }
 346         while ((n = *cp++) != 0) {
 347                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 348                         /* Some kind of compression pointer. */
 349                         __set_errno (EMSGSIZE);
 350                         return (-1);
 351                 }
 352                 *dn++ = n;
 353                 if ((l = labellen(cp - 1)) < 0) {
 354                         __set_errno (EMSGSIZE);
 355                         return (-1);
 356                 }
 357                 if (dn + l >= eom) {
 358                         __set_errno (EMSGSIZE);
 359                         return (-1);
 360                 }
 361                 for ((void)NULL; l > 0; l--) {
 362                         c = *cp++;
 363                         if (isupper(c))
 364                                 *dn++ = tolower(c);
 365                         else
 366                                 *dn++ = c;
 367                 }
 368         }
 369         *dn++ = '\0';
 370         return (dn - dst);
 371 }
 372
 373 /*%
 374  *      Unpack a domain name from a message, source may be compressed.
 375  *
 376  * return:
 377  *\li   -1 if it fails, or consumed octets if it succeeds.
 378  */
 379 int
 380 ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
 381                u_char *dst, size_t dstsiz)
 382 {
 383         const u_char *srcp, *dstlim;
 384         u_char *dstp;
 385         int n, len, checked, l;
 386
 387         len = -1;
 388         checked = 0;
 389         dstp = dst;
 390         srcp = src;
 391         dstlim = dst + dstsiz;
 392         if (srcp < msg || srcp >= eom) {
 393                 __set_errno (EMSGSIZE);
 394                 return (-1);
 395         }
 396         /* Fetch next label in domain name. */
 397         while ((n = *srcp++) != 0) {
 398                 /* Check for indirection. */
 399                 switch (n & NS_CMPRSFLGS) {
 400                 case 0:
 401                 case NS_TYPE_ELT:
 402                         /* Limit checks. */
 403                         if ((l = labellen(srcp - 1)) < 0) {
 404                                 __set_errno (EMSGSIZE);
 405                                 return(-1);
 406                         }
 407                         if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
 408                                 __set_errno (EMSGSIZE);
 409                                 return (-1);
 410                         }
 411                         checked += l + 1;
 412                         *dstp++ = n;
 413                         memcpy(dstp, srcp, l);
 414                         dstp += l;
 415                         srcp += l;
 416                         break;
 417
 418                 case NS_CMPRSFLGS:
 419                         if (srcp >= eom) {
 420                                 __set_errno (EMSGSIZE);
 421                                 return (-1);
 422                         }
 423                         if (len < 0)
 424                                 len = srcp - src + 1;
 425                         srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
 426                         if (srcp < msg || srcp >= eom) {  /*%< Out of range. */
 427                                 __set_errno (EMSGSIZE);
 428                                 return (-1);
 429                         }
 430                         checked += 2;
 431                         /*
 432                          * Check for loops in the compressed name;
 433                          * if we've looked at the whole message,
 434                          * there must be a loop.
 435                          */
 436                         if (checked >= eom - msg) {
 437                                 __set_errno (EMSGSIZE);
 438                                 return (-1);
 439                         }
 440                         break;
 441
 442                 default:
 443                         __set_errno (EMSGSIZE);
 444                         return (-1);                    /*%< flag error */
 445                 }
 446         }
 447         *dstp = '\0';
 448         if (len < 0)
 449                 len = srcp - src;
 450         return (len);
 451 }
 452 libresolv_hidden_def (ns_name_unpack)
 453 strong_alias (ns_name_unpack, __ns_name_unpack)
 454
 455 /*%
 456  *      Pack domain name 'domain' into 'comp_dn'.
 457  *
 458  * return:
 459  *\li   Size of the compressed name, or -1.
 460  *
 461  * notes:
 462  *\li   'dnptrs' is an array of pointers to previous compressed names.
 463  *\li   dnptrs[0] is a pointer to the beginning of the message. The array
 464  *      ends with NULL.
 465  *\li   'lastdnptr' is a pointer to the end of the array pointed to
 466  *      by 'dnptrs'.
 467  *
 468  * Side effects:
 469  *\li   The list of pointers in dnptrs is updated for labels inserted into
 470  *      the message as we compress the name.  If 'dnptr' is NULL, we don't
 471  *      try to compress names. If 'lastdnptr' is NULL, we don't update the
 472  *      list.
 473  */
 474 int
 475 ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
 476              const u_char **dnptrs, const u_char **lastdnptr)
 477 {
 478         u_char *dstp;
 479         const u_char **cpp, **lpp, *eob, *msg;
 480         const u_char *srcp;
 481         int n, l, first = 1;
 482
 483         srcp = src;
 484         dstp = dst;
 485         eob = dstp + dstsiz;
 486         lpp = cpp = NULL;
 487         if (dnptrs != NULL) {
 488                 if ((msg = *dnptrs++) != NULL) {
 489                         for (cpp = dnptrs; *cpp != NULL; cpp++)
 490                                 (void)NULL;
 491                         lpp = cpp;      /*%< end of list to search */
 492                 }
 493         } else
 494                 msg = NULL;
 495
 496         /* make sure the domain we are about to add is legal */
 497         l = 0;
 498         do {
 499                 int l0;
 500
 501                 n = *srcp;
 502                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 503                         __set_errno (EMSGSIZE);
 504                         return (-1);
 505                 }
 506                 if ((l0 = labellen(srcp)) < 0) {
 507                         __set_errno (EINVAL);
 508                         return(-1);
 509                 }
 510                 l += l0 + 1;
 511                 if (l > MAXCDNAME) {
 512                         __set_errno (EMSGSIZE);
 513                         return (-1);
 514                 }
 515                 srcp += l0 + 1;
 516         } while (n != 0);
 517
 518         /* from here on we need to reset compression pointer array on error */
 519         srcp = src;
 520         do {
 521                 /* Look to see if we can use pointers. */
 522                 n = *srcp;
 523                 if (n != 0 && msg != NULL) {
 524                         l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
 525                                     (const u_char * const *)lpp);
 526                         if (l >= 0) {
 527                                 if (dstp + 1 >= eob) {
 528                                         goto cleanup;
 529                                 }
 530                                 *dstp++ = (l >> 8) | NS_CMPRSFLGS;
 531                                 *dstp++ = l % 256;
 532                                 return (dstp - dst);
 533                         }
 534                         /* Not found, save it. */
 535                         if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
 536                             (dstp - msg) < 0x4000 && first) {
 537                                 *cpp++ = dstp;
 538                                 *cpp = NULL;
 539                                 first = 0;
 540                         }
 541                 }
 542                 /* copy label to buffer */
 543                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 544                         /* Should not happen. */
 545                         goto cleanup;
 546                 }
 547                 n = labellen(srcp);
 548                 if (dstp + 1 + n >= eob) {
 549                         goto cleanup;
 550                 }
 551                 memcpy(dstp, srcp, n + 1);
 552                 srcp += n + 1;
 553                 dstp += n + 1;
 554         } while (n != 0);
 555
 556         if (dstp > eob) {
 557 cleanup:
 558                 if (msg != NULL)
 559                         *lpp = NULL;
 560                 __set_errno (EMSGSIZE);
 561                 return (-1);
 562         }
 563         return (dstp - dst);
 564 }
 565 libresolv_hidden_def (ns_name_pack)
 566
 567 /*%
 568  *      Expand compressed domain name to presentation format.
 569  *
 570  * return:
 571  *\li   Number of bytes read out of `src', or -1 (with errno set).
 572  *
 573  * note:
 574  *\li   Root domain returns as "." not "".
 575  */
 576 int
 577 ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
 578                    char *dst, size_t dstsiz)
 579 {
 580         u_char tmp[NS_MAXCDNAME];
 581         int n;
 582
 583         if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
 584                 return (-1);
 585         if (ns_name_ntop(tmp, dst, dstsiz) == -1)
 586                 return (-1);
 587         return (n);
 588 }
 589 libresolv_hidden_def (ns_name_uncompress)
 590
 591 /*%
 592  *      Compress a domain name into wire format, using compression pointers.
 593  *
 594  * return:
 595  *\li   Number of bytes consumed in `dst' or -1 (with errno set).
 596  *
 597  * notes:
 598  *\li   'dnptrs' is an array of pointers to previous compressed names.
 599  *\li   dnptrs[0] is a pointer to the beginning of the message.
 600  *\li   The list ends with NULL.  'lastdnptr' is a pointer to the end of the
 601  *      array pointed to by 'dnptrs'. Side effect is to update the list of
 602  *      pointers for labels inserted into the message as we compress the name.
 603  *\li   If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
 604  *      is NULL, we don't update the list.
 605  */
 606 int
 607 ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
 608                  const u_char **dnptrs, const u_char **lastdnptr)
 609 {
 610         u_char tmp[NS_MAXCDNAME];
 611
 612         if (ns_name_pton(src, tmp, sizeof tmp) == -1)
 613                 return (-1);
 614         return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
 615 }
 616 libresolv_hidden_def (ns_name_compress)
 617
 618 /*%
 619  * Reset dnptrs so that there are no active references to pointers at or
 620  * after src.
 621  */
 622 void
 623 ns_name_rollback(const u_char *src, const u_char **dnptrs,
 624                  const u_char **lastdnptr)
 625 {
 626         while (dnptrs < lastdnptr && *dnptrs != NULL) {
 627                 if (*dnptrs >= src) {
 628                         *dnptrs = NULL;
 629                         break;
 630                 }
 631                 dnptrs++;
 632         }
 633 }
 634
 635 /*%
 636  *      Advance *ptrptr to skip over the compressed name it points at.
 637  *
 638  * return:
 639  *\li   0 on success, -1 (with errno set) on failure.
 640  */
 641 int
 642 ns_name_skip(const u_char **ptrptr, const u_char *eom)
 643 {
 644         const u_char *cp;
 645         u_int n;
 646         int l;
 647
 648         cp = *ptrptr;
 649         while (cp < eom && (n = *cp++) != 0) {
 650                 /* Check for indirection. */
 651                 switch (n & NS_CMPRSFLGS) {
 652                 case 0:                 /*%< normal case, n == len */
 653                         cp += n;
 654                         continue;
 655                 case NS_TYPE_ELT: /*%< EDNS0 extended label */
 656                         if ((l = labellen(cp - 1)) < 0) {
 657                                 __set_errno (EMSGSIZE);
 658                                 return(-1);
 659                         }
 660                         cp += l;
 661                         continue;
 662                 case NS_CMPRSFLGS:      /*%< indirection */
 663                         cp++;
 664                         break;
 665                 default:                /*%< illegal type */
 666                         __set_errno (EMSGSIZE);
 667                         return (-1);
 668                 }
 669                 break;
 670         }
 671         if (cp > eom) {
 672                 __set_errno (EMSGSIZE);
 673                 return (-1);
 674         }
 675         *ptrptr = cp;
 676         return (0);
 677 }
 678 libresolv_hidden_def (ns_name_skip)
 679
 680 /* Private. */
 681
 682 /*%
 683  *      Thinking in noninternationalized USASCII (per the DNS spec),
 684  *      is this characted special ("in need of quoting") ?
 685  *
 686  * return:
 687  *\li   boolean.
 688  */
 689 static int
 690 special(int ch) {
 691         switch (ch) {
 692         case 0x22: /*%< '"' */
 693         case 0x2E: /*%< '.' */
 694         case 0x3B: /*%< ';' */
 695         case 0x5C: /*%< '\\' */
 696         case 0x28: /*%< '(' */
 697         case 0x29: /*%< ')' */
 698         /* Special modifiers in zone files. */
 699         case 0x40: /*%< '@' */
 700         case 0x24: /*%< '$' */
 701                 return (1);
 702         default:
 703                 return (0);
 704         }
 705 }
 706
 707 /*%
 708  *      Thinking in noninternationalized USASCII (per the DNS spec),
 709  *      is this character visible and not a space when printed ?
 710  *
 711  * return:
 712  *\li   boolean.
 713  */
 714 static int
 715 printable(int ch) {
 716         return (ch > 0x20 && ch < 0x7f);
 717 }
 718
 719 /*%
 720  *      Thinking in noninternationalized USASCII (per the DNS spec),
 721  *      convert this character to lower case if it's upper case.
 722  */
 723 static int
 724 mklower(int ch) {
 725         if (ch >= 0x41 && ch <= 0x5A)
 726                 return (ch + 0x20);
 727         return (ch);
 728 }
 729
 730 /*%
 731  *      Search for the counted-label name in an array of compressed names.
 732  *
 733  * return:
 734  *\li   offset from msg if found, or -1.
 735  *
 736  * notes:
 737  *\li   dnptrs is the pointer to the first name on the list,
 738  *\li   not the pointer to the start of the message.
 739  */
 740 static int
 741 dn_find(const u_char *domain, const u_char *msg,
 742         const u_char * const *dnptrs,
 743         const u_char * const *lastdnptr)
 744 {
 745         const u_char *dn, *cp, *sp;
 746         const u_char * const *cpp;
 747         u_int n;
 748
 749         for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
 750                 sp = *cpp;
 751                 /*
 752                  * terminate search on:
 753                  * root label
 754                  * compression pointer
 755                  * unusable offset
 756                  */
 757                 while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
 758                        (sp - msg) < 0x4000) {
 759                         dn = domain;
 760                         cp = sp;
 761                         while ((n = *cp++) != 0) {
 762                                 /*
 763                                  * check for indirection
 764                                  */
 765                                 switch (n & NS_CMPRSFLGS) {
 766                                 case 0:         /*%< normal case, n == len */
 767                                         n = labellen(cp - 1); /*%< XXX */
 768                                         if (n != *dn++)
 769                                                 goto next;
 770
 771                                         for ((void)NULL; n > 0; n--)
 772                                                 if (mklower(*dn++) !=
 773                                                     mklower(*cp++))
 774                                                         goto next;
 775                                         /* Is next root for both ? */
 776                                         if (*dn == '\0' && *cp == '\0')
 777                                                 return (sp - msg);
 778                                         if (*dn)
 779                                                 continue;
 780                                         goto next;
 781                                 case NS_CMPRSFLGS:      /*%< indirection */
 782                                         cp = msg + (((n & 0x3f) << 8) | *cp);
 783                                         break;
 784
 785                                 default:        /*%< illegal type */
 786                                         __set_errno (EMSGSIZE);
 787                                         return (-1);
 788                                 }
 789                         }
 790   next: ;
 791                         sp += *sp + 1;
 792                 }
 793         }
 794         __set_errno (ENOENT);
 795         return (-1);
 796 }
 797
 798 static int
 799 decode_bitstring(const unsigned char **cpp, char *dn, const char *eom)
 800 {
 801         const unsigned char *cp = *cpp;
 802         char *beg = dn, tc;
 803         int b, blen, plen, i;
 804
 805         if ((blen = (*cp & 0xff)) == 0)
 806                 blen = 256;
 807         plen = (blen + 3) / 4;
 808         plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
 809         if (dn + plen >= eom)
 810                 return(-1);
 811
 812         cp++;
 813         i = SPRINTF((dn, "\\[x"));
 814         if (i < 0)
 815                 return (-1);
 816         dn += i;
 817         for (b = blen; b > 7; b -= 8, cp++) {
 818                 i = SPRINTF((dn, "%02x", *cp & 0xff));
 819                 if (i < 0)
 820                         return (-1);
 821                 dn += i;
 822         }
 823         if (b > 4) {
 824                 tc = *cp++;
 825                 i = SPRINTF((dn, "%02x", tc & (0xff << (8 - b))));
 826                 if (i < 0)
 827                         return (-1);
 828                 dn += i;
 829         } else if (b > 0) {
 830                 tc = *cp++;
 831                 i = SPRINTF((dn, "%1x",
 832                                ((tc >> 4) & 0x0f) & (0x0f << (4 - b))));
 833                 if (i < 0)
 834                         return (-1);
 835                 dn += i;
 836         }
 837         i = SPRINTF((dn, "/%d]", blen));
 838         if (i < 0)
 839                 return (-1);
 840         dn += i;
 841
 842         *cpp = cp;
 843         return(dn - beg);
 844 }
 845
 846 static int
 847 encode_bitstring(const char **bp, const char *end, unsigned char **labelp,
 848                  unsigned char ** dst, unsigned const char *eom)
 849 {
 850         int afterslash = 0;
 851         const char *cp = *bp;
 852         unsigned char *tp;
 853         char c;
 854         const char *beg_blen;
 855         char *end_blen = NULL;
 856         int value = 0, count = 0, tbcount = 0, blen = 0;
 857
 858         beg_blen = end_blen = NULL;
 859
 860         /* a bitstring must contain at least 2 characters */
 861         if (end - cp < 2)
 862                 return(EINVAL);
 863
 864         /* XXX: currently, only hex strings are supported */
 865         if (*cp++ != 'x')
 866                 return(EINVAL);
 867         if (!isxdigit((*cp) & 0xff)) /*%< reject '\[x/BLEN]' */
 868                 return(EINVAL);
 869
 870         for (tp = *dst + 1; cp < end && tp < eom; cp++) {
 871                 switch((c = *cp)) {
 872                 case ']':       /*%< end of the bitstring */
 873                         if (afterslash) {
 874                                 if (beg_blen == NULL)
 875                                         return(EINVAL);
 876                                 blen = (int)strtol(beg_blen, &end_blen, 10);
 877                                 if (*end_blen != ']')
 878                                         return(EINVAL);
 879                         }
 880                         if (count)
 881                                 *tp++ = ((value << 4) & 0xff);
 882                         cp++;   /*%< skip ']' */
 883                         goto done;
 884                 case '/':
 885                         afterslash = 1;
 886                         break;
 887                 default:
 888                         if (afterslash) {
 889                                 if (!isdigit(c&0xff))
 890                                         return(EINVAL);
 891                                 if (beg_blen == NULL) {
 892
 893                                         if (c == '0') {
 894                                                 /* blen never begings with 0 */
 895                                                 return(EINVAL);
 896                                         }
 897                                         beg_blen = cp;
 898                                 }
 899                         } else {
 900                                 if (!isxdigit(c&0xff))
 901                                         return(EINVAL);
 902                                 value <<= 4;
 903                                 value += digitvalue[(int)c];
 904                                 count += 4;
 905                                 tbcount += 4;
 906                                 if (tbcount > 256)
 907                                         return(EINVAL);
 908                                 if (count == 8) {
 909                                         *tp++ = value;
 910                                         count = 0;
 911                                 }
 912                         }
 913                         break;
 914                 }
 915         }
 916   done:
 917         if (cp >= end || tp >= eom)
 918                 return(EMSGSIZE);
 919
 920         /*
 921          * bit length validation:
 922          * If a <length> is present, the number of digits in the <bit-data>
 923          * MUST be just sufficient to contain the number of bits specified
 924          * by the <length>. If there are insignificant bits in a final
 925          * hexadecimal or octal digit, they MUST be zero.
 926          * RFC2673, Section 3.2.
 927          */
 928         if (blen > 0) {
 929                 int traillen;
 930
 931                 if (((blen + 3) & ~3) != tbcount)
 932                         return(EINVAL);
 933                 traillen = tbcount - blen; /*%< between 0 and 3 */
 934                 if (((value << (8 - traillen)) & 0xff) != 0)
 935                         return(EINVAL);
 936         }
 937         else
 938                 blen = tbcount;
 939         if (blen == 256)
 940                 blen = 0;
 941
 942         /* encode the type and the significant bit fields */
 943         **labelp = DNS_LABELTYPE_BITSTRING;
 944         **dst = blen;
 945
 946         *bp = cp;
 947         *dst = tp;
 948
 949         return(0);
 950 }
 951
 952 static int
 953 labellen(const u_char *lp)
 954 {
 955         int bitlen;
 956         u_char l = *lp;
 957
 958         if ((l & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 959                 /* should be avoided by the caller */
 960                 return(-1);
 961         }
 962
 963         if ((l & NS_CMPRSFLGS) == NS_TYPE_ELT) {
 964                 if (l == DNS_LABELTYPE_BITSTRING) {
 965                         if ((bitlen = *(lp + 1)) == 0)
 966                                 bitlen = 256;
 967                         return((bitlen + 7 ) / 8 + 1);
 968                 }
 969                 return(-1);     /*%< unknwon ELT */
 970         }
 971         return(l);
 972 }
 973
 974 /*! \file */