StdLib/BsdSocketLib/ns_name.c

   1 /*
   2  * Copyright (c) 1996 by Internet Software Consortium.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
   9  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  10  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  11  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  12  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  13  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  14  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  15  * SOFTWARE.
  16  */
  17
  18 /*
  19  * Portions copyright (c) 1999, 2000
  20  * Intel Corporation.
  21  * All rights reserved.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  *
  27  * 1. Redistributions of source code must retain the above copyright
  28  *    notice, this list of conditions and the following disclaimer.
  29  *
  30  * 2. Redistributions in binary form must reproduce the above copyright
  31  *    notice, this list of conditions and the following disclaimer in the
  32  *    documentation and/or other materials provided with the distribution.
  33  *
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *
  37  *    This product includes software developed by Intel Corporation and
  38  *    its contributors.
  39  *
  40  * 4. Neither the name of Intel Corporation or its contributors may be
  41  *    used to endorse or promote products derived from this software
  42  *    without specific prior written permission.
  43  *
  44  * THIS SOFTWARE IS PROVIDED BY INTEL CORPORATION AND CONTRIBUTORS ``AS IS''
  45  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47  * ARE DISCLAIMED.  IN NO EVENT SHALL INTEL CORPORATION OR CONTRIBUTORS BE
  48  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  49  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  50  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  51  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  52  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  53  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  54  * THE POSSIBILITY OF SUCH DAMAGE.
  55  *
  56  */
  57
  58 #include <sys/types.h>
  59
  60 #include <netinet/in.h>
  61 #include <arpa/nameser.h>
  62
  63 #include <errno.h>
  64 #include <resolv.h>
  65 #include <string.h>
  66
  67 /* Data. */
  68
  69 static char             digits[] = "0123456789";
  70
  71 /* Forward. */
  72
  73 static int              special(int);
  74 static int              printable(int);
  75 static int              dn_find(const u_char *, const u_char *,
  76                                 const u_char * const *,
  77                                 const u_char * const *);
  78
  79 /* Public. */
  80
  81 /*
  82  * ns_name_ntop(src, dst, dstsiz)
  83  *      Convert an encoded domain name to printable ascii as per RFC1035.
  84  * return:
  85  *      Number of bytes written to buffer, or -1 (with errno set)
  86  * notes:
  87  *      The root is returned as "."
  88  *      All other domains are returned in non absolute form
  89  */
  90 int
  91 ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) {
  92         const u_char *cp;
  93         char *dn, *eom;
  94         u_char c;
  95         u_int n;
  96
  97         cp = src;
  98         dn = dst;
  99         eom = dst + dstsiz;
 100
 101         while ((n = *cp++) != 0) {
 102                 if ((n & NS_CMPRSFLGS) != 0) {
 103                         /* Some kind of compression pointer. */
 104                         errno = EMSGSIZE;
 105                         return (-1);
 106                 }
 107                 if (dn != dst) {
 108                         if (dn >= eom) {
 109                                 errno = EMSGSIZE;
 110                                 return (-1);
 111                         }
 112                         *dn++ = '.';
 113                 }
 114                 if (dn + n >= eom) {
 115                         errno = EMSGSIZE;
 116                         return (-1);
 117                 }
 118                 for ((void)NULL; n > 0; n--) {
 119                         c = *cp++;
 120                         if (special(c)) {
 121                                 if (dn + 1 >= eom) {
 122                                         errno = EMSGSIZE;
 123                                         return (-1);
 124                                 }
 125                                 *dn++ = '\\';
 126                                 *dn++ = (char)c;
 127                         } else if (!printable(c)) {
 128                                 if (dn + 3 >= eom) {
 129                                         errno = EMSGSIZE;
 130                                         return (-1);
 131                                 }
 132                                 *dn++ = '\\';
 133                                 *dn++ = digits[c / 100];
 134                                 *dn++ = digits[(c % 100) / 10];
 135                                 *dn++ = digits[c % 10];
 136                         } else {
 137                                 if (dn >= eom) {
 138                                         errno = EMSGSIZE;
 139                                         return (-1);
 140                                 }
 141                                 *dn++ = (char)c;
 142                         }
 143                 }
 144         }
 145         if (dn == dst) {
 146                 if (dn >= eom) {
 147                         errno = EMSGSIZE;
 148                         return (-1);
 149                 }
 150                 *dn++ = '.';
 151         }
 152         if (dn >= eom) {
 153                 errno = EMSGSIZE;
 154                 return (-1);
 155         }
 156         *dn++ = '\0';
 157         return ((int)(dn - dst));
 158 }
 159
 160 /*
 161  * ns_name_pton(src, dst, dstsiz)
 162  *      Convert a ascii string into an encoded domain name as per RFC1035.
 163  * return:
 164  *      -1 if it fails
 165  *      1 if string was fully qualified
 166  *      0 is string was not fully qualified
 167  * notes:
 168  *      Enforces label and domain length limits.
 169  */
 170
 171 int
 172 ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
 173         u_char *label, *bp, *eom;
 174         int c, n, escaped;
 175         char *cp;
 176
 177         escaped = 0;
 178         bp = dst;
 179         eom = dst + dstsiz;
 180         label = bp++;
 181
 182         while ((c = *src++) != 0) {
 183                 if (escaped) {
 184                         if ((cp = strchr(digits, c)) != NULL) {
 185                                 n = (int)(cp - digits) * 100;
 186                                 if ((c = *src++) == 0 ||
 187                                     (cp = strchr(digits, c)) == NULL) {
 188                                         errno = EMSGSIZE;
 189                                         return (-1);
 190                                 }
 191                                 n += (int)(cp - digits) * 10;
 192                                 if ((c = *src++) == 0 ||
 193                                     (cp = strchr(digits, c)) == NULL) {
 194                                         errno = EMSGSIZE;
 195                                         return (-1);
 196                                 }
 197                                 n += (int)(cp - digits);
 198                                 if (n > 255) {
 199                                         errno = EMSGSIZE;
 200                                         return (-1);
 201                                 }
 202                                 c = n;
 203                         }
 204                         escaped = 0;
 205                 } else if (c == '\\') {
 206                         escaped = 1;
 207                         continue;
 208                 } else if (c == '.') {
 209                         c = ((int)(bp - label) - 1);
 210                         if ((c & NS_CMPRSFLGS) != 0) {  /* Label too big. */
 211                                 errno = EMSGSIZE;
 212                                 return (-1);
 213                         }
 214                         if (label >= eom) {
 215                                 errno = EMSGSIZE;
 216                                 return (-1);
 217                         }
 218                         *label = (u_char)c;
 219                         /* Fully qualified ? */
 220                         if (*src == '\0') {
 221                                 if (c != 0) {
 222                                         if (bp >= eom) {
 223                                                 errno = EMSGSIZE;
 224                                                 return (-1);
 225                                         }
 226                                         *bp++ = '\0';
 227                                 }
 228                                 if ((bp - dst) > MAXCDNAME) {
 229                                         errno = EMSGSIZE;
 230                                         return (-1);
 231                                 }
 232                                 return (1);
 233                         }
 234                         if (c == 0) {
 235                                 errno = EMSGSIZE;
 236                                 return (-1);
 237                         }
 238                         label = bp++;
 239                         continue;
 240                 }
 241                 if (bp >= eom) {
 242                         errno = EMSGSIZE;
 243                         return (-1);
 244                 }
 245                 *bp++ = (u_char)c;
 246         }
 247         c = ((int)(bp - label) - 1);
 248         if ((c & NS_CMPRSFLGS) != 0) {          /* Label too big. */
 249                 errno = EMSGSIZE;
 250                 return (-1);
 251         }
 252         if (label >= eom) {
 253                 errno = EMSGSIZE;
 254                 return (-1);
 255         }
 256         *label = (u_char)c;
 257         if (c != 0) {
 258                 if (bp >= eom) {
 259                         errno = EMSGSIZE;
 260                         return (-1);
 261                 }
 262                 *bp++ = 0;
 263         }
 264         if ((bp - dst) > MAXCDNAME) {   /* src too big */
 265                 errno = EMSGSIZE;
 266                 return (-1);
 267         }
 268         return (0);
 269 }
 270
 271 /*
 272  * ns_name_unpack(msg, eom, src, dst, dstsiz)
 273  *      Unpack a domain name from a message, source may be compressed.
 274  * return:
 275  *      -1 if it fails, or consumed octets if it succeeds.
 276  */
 277 int
 278 ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
 279                u_char *dst, size_t dstsiz)
 280 {
 281         const u_char *srcp, *dstlim;
 282         u_char *dstp;
 283         int n, len, checked;
 284
 285         len = -1;
 286         checked = 0;
 287         dstp = dst;
 288         srcp = src;
 289         dstlim = dst + dstsiz;
 290         if (srcp < msg || srcp >= eom) {
 291                 errno = EMSGSIZE;
 292                 return (-1);
 293         }
 294         /* Fetch next label in domain name. */
 295         while ((n = *srcp++) != 0) {
 296                 /* Check for indirection. */
 297                 switch (n & NS_CMPRSFLGS) {
 298                 case 0:
 299                         /* Limit checks. */
 300                         if (dstp + n + 1 >= dstlim || srcp + n >= eom) {
 301                                 errno = EMSGSIZE;
 302                                 return (-1);
 303                         }
 304                         checked += n + 1;
 305                         *dstp++ = (u_char)n;
 306                         memcpy(dstp, srcp, n);
 307                         dstp += n;
 308                         srcp += n;
 309                         break;
 310
 311                 case NS_CMPRSFLGS:
 312                         if (srcp >= eom) {
 313                                 errno = EMSGSIZE;
 314                                 return (-1);
 315                         }
 316                         if (len < 0)
 317                                 len = (int)(srcp - src) + 1;
 318                         srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
 319                         if (srcp < msg || srcp >= eom) {  /* Out of range. */
 320                                 errno = EMSGSIZE;
 321                                 return (-1);
 322                         }
 323                         checked += 2;
 324                         /*
 325                          * Check for loops in the compressed name;
 326                          * if we've looked at the whole message,
 327                          * there must be a loop.
 328                          */
 329                         if (checked >= eom - msg) {
 330                                 errno = EMSGSIZE;
 331                                 return (-1);
 332                         }
 333                         break;
 334
 335                 default:
 336                         errno = EMSGSIZE;
 337                         return (-1);                    /* flag error */
 338                 }
 339         }
 340         *dstp = '\0';
 341         if (len < 0)
 342                 len = (int)(srcp - src);
 343         return (len);
 344 }
 345
 346 /*
 347  * ns_name_pack(src, dst, dstsiz, dnptrs, lastdnptr)
 348  *      Pack domain name 'domain' into 'comp_dn'.
 349  * return:
 350  *      Size of the compressed name, or -1.
 351  * notes:
 352  *      'dnptrs' is an array of pointers to previous compressed names.
 353  *      dnptrs[0] is a pointer to the beginning of the message. The array
 354  *      ends with NULL.
 355  *      'lastdnptr' is a pointer to the end of the array pointed to
 356  *      by 'dnptrs'.
 357  * Side effects:
 358  *      The list of pointers in dnptrs is updated for labels inserted into
 359  *      the message as we compress the name.  If 'dnptr' is NULL, we don't
 360  *      try to compress names. If 'lastdnptr' is NULL, we don't update the
 361  *      list.
 362  */
 363 int
 364 ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
 365              const u_char **dnptrs, const u_char **lastdnptr)
 366 {
 367         u_char *dstp;
 368         const u_char **cpp, **lpp, *eob, *msg;
 369         const u_char *srcp;
 370         int n, l;
 371
 372         srcp = src;
 373         dstp = dst;
 374         eob = dstp + dstsiz;
 375         lpp = cpp = NULL;
 376         if (dnptrs != NULL) {
 377                 if ((msg = *dnptrs++) != NULL) {
 378                         for (cpp = dnptrs; *cpp != NULL; cpp++)
 379                                 (void)NULL;
 380                         lpp = cpp;      /* end of list to search */
 381                 }
 382         } else
 383                 msg = NULL;
 384
 385         /* make sure the domain we are about to add is legal */
 386         l = 0;
 387         do {
 388                 n = *srcp;
 389                 if ((n & NS_CMPRSFLGS) != 0) {
 390                         errno = EMSGSIZE;
 391                         return (-1);
 392                 }
 393                 l += n + 1;
 394                 if (l > MAXCDNAME) {
 395                         errno = EMSGSIZE;
 396                         return (-1);
 397                 }
 398                 srcp += n + 1;
 399         } while (n != 0);
 400
 401         srcp = src;
 402         do {
 403                 /* Look to see if we can use pointers. */
 404                 n = *srcp;
 405                 if (n != 0 && msg != NULL) {
 406                         l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
 407                                     (const u_char * const *)lpp);
 408                         if (l >= 0) {
 409                                 if (dstp + 1 >= eob) {
 410                                         errno = EMSGSIZE;
 411                                         return (-1);
 412                                 }
 413                                 *dstp++ = (u_char)((l >> 8) | NS_CMPRSFLGS );
 414                                 *dstp++ = (u_char)( l % 256 );
 415                                 return ((int)(dstp - dst));
 416                         }
 417                         /* Not found, save it. */
 418                         if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
 419                             (dstp - msg) < 0x4000) {
 420                                 *cpp++ = dstp;
 421                                 *cpp = NULL;
 422                         }
 423                 }
 424                 /* copy label to buffer */
 425                 if (n & NS_CMPRSFLGS) {         /* Should not happen. */
 426                         errno = EMSGSIZE;
 427                         return (-1);
 428                 }
 429                 if (dstp + 1 + n >= eob) {
 430                         errno = EMSGSIZE;
 431                         return (-1);
 432                 }
 433                 memcpy(dstp, srcp, n + 1);
 434                 srcp += n + 1;
 435                 dstp += n + 1;
 436         } while (n != 0);
 437
 438         if (dstp > eob) {
 439                 if (msg != NULL)
 440                         *lpp = NULL;
 441                 errno = EMSGSIZE;
 442                 return (-1);
 443         }
 444         return ((int)(dstp - dst));
 445 }
 446
 447 /*
 448  * ns_name_uncompress(msg, eom, src, dst, dstsiz)
 449  *      Expand compressed domain name to presentation format.
 450  * return:
 451  *      Number of bytes read out of `src', or -1 (with errno set).
 452  * note:
 453  *      Root domain returns as "." not "".
 454  */
 455 int
 456 ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
 457                    char *dst, size_t dstsiz)
 458 {
 459         u_char tmp[NS_MAXCDNAME];
 460         int n;
 461
 462         if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
 463                 return (-1);
 464         if (ns_name_ntop(tmp, dst, dstsiz) == -1)
 465                 return (-1);
 466         return (n);
 467 }
 468
 469 /*
 470  * ns_name_compress(src, dst, dstsiz, dnptrs, lastdnptr)
 471  *      Compress a domain name into wire format, using compression pointers.
 472  * return:
 473  *      Number of bytes consumed in `dst' or -1 (with errno set).
 474  * notes:
 475  *      'dnptrs' is an array of pointers to previous compressed names.
 476  *      dnptrs[0] is a pointer to the beginning of the message.
 477  *      The list ends with NULL.  'lastdnptr' is a pointer to the end of the
 478  *      array pointed to by 'dnptrs'. Side effect is to update the list of
 479  *      pointers for labels inserted into the message as we compress the name.
 480  *      If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
 481  *      is NULL, we don't update the list.
 482  */
 483 int
 484 ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
 485                  const u_char **dnptrs, const u_char **lastdnptr)
 486 {
 487         u_char tmp[NS_MAXCDNAME];
 488
 489         if (ns_name_pton(src, tmp, sizeof tmp) == -1)
 490                 return (-1);
 491         return (ns_name_pack(tmp, dst, (int)dstsiz, dnptrs, lastdnptr));
 492 }
 493
 494 /*
 495  * ns_name_skip(ptrptr, eom)
 496  *      Advance *ptrptr to skip over the compressed name it points at.
 497  * return:
 498  *      0 on success, -1 (with errno set) on failure.
 499  */
 500 int
 501 ns_name_skip(const u_char **ptrptr, const u_char *eom) {
 502         const u_char *cp;
 503         u_int n;
 504
 505         cp = *ptrptr;
 506         while (cp < eom && (n = *cp++) != 0) {
 507                 /* Check for indirection. */
 508                 switch (n & NS_CMPRSFLGS) {
 509                 case 0:                 /* normal case, n == len */
 510                         cp += n;
 511                         continue;
 512                 case NS_CMPRSFLGS:      /* indirection */
 513                         cp++;
 514                         break;
 515                 default:                /* illegal type */
 516                         errno = EMSGSIZE;
 517                         return (-1);
 518                 }
 519                 break;
 520         }
 521         if (cp > eom) {
 522                 errno = EMSGSIZE;
 523                 return (-1);
 524         }
 525         *ptrptr = cp;
 526         return (0);
 527 }
 528
 529 /* Private. */
 530
 531 /*
 532  * special(ch)
 533  *      Thinking in noninternationalized USASCII (per the DNS spec),
 534  *      is this characted special ("in need of quoting") ?
 535  * return:
 536  *      boolean.
 537  */
 538 static int
 539 special(int ch) {
 540         switch (ch) {
 541         case 0x22: /* '"' */
 542         case 0x2E: /* '.' */
 543         case 0x3B: /* ';' */
 544         case 0x5C: /* '\\' */
 545         /* Special modifiers in zone files. */
 546         case 0x40: /* '@' */
 547         case 0x24: /* '$' */
 548                 return (1);
 549         default:
 550                 return (0);
 551         }
 552 }
 553
 554 /*
 555  * printable(ch)
 556  *      Thinking in noninternationalized USASCII (per the DNS spec),
 557  *      is this character visible and not a space when printed ?
 558  * return:
 559  *      boolean.
 560  */
 561 static int
 562 printable(int ch) {
 563         return (ch > 0x20 && ch < 0x7f);
 564 }
 565
 566 /*
 567  *      Thinking in noninternationalized USASCII (per the DNS spec),
 568  *      convert this character to lower case if it's upper case.
 569  */
 570 static int
 571 mklower(int ch) {
 572         if (ch >= 0x41 && ch <= 0x5A)
 573                 return (ch + 0x20);
 574         return (ch);
 575 }
 576
 577 /*
 578  * dn_find(domain, msg, dnptrs, lastdnptr)
 579  *      Search for the counted-label name in an array of compressed names.
 580  * return:
 581  *      offset from msg if found, or -1.
 582  * notes:
 583  *      dnptrs is the pointer to the first name on the list,
 584  *      not the pointer to the start of the message.
 585  */
 586 static int
 587 dn_find(const u_char *domain, const u_char *msg,
 588         const u_char * const *dnptrs,
 589         const u_char * const *lastdnptr)
 590 {
 591         const u_char *dn, *cp, *sp;
 592         const u_char * const *cpp;
 593         u_int n;
 594
 595         for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
 596                 dn = domain;
 597                 sp = cp = *cpp;
 598                 while ((n = *cp++) != 0) {
 599                         /*
 600                          * check for indirection
 601                          */
 602                         switch (n & NS_CMPRSFLGS) {
 603                         case 0:                 /* normal case, n == len */
 604                                 if (n != *dn++)
 605                                         goto next;
 606                                 for ((void)NULL; n > 0; n--)
 607                                         if (mklower(*dn++) != mklower(*cp++))
 608                                                 goto next;
 609                                 /* Is next root for both ? */
 610                                 if (*dn == '\0' && *cp == '\0')
 611                                         return ((int)(sp - msg));
 612                                 if (*dn)
 613                                         continue;
 614                                 goto next;
 615
 616                         case NS_CMPRSFLGS:      /* indirection */
 617                                 cp = msg + (((n & 0x3f) << 8) | *cp);
 618                                 break;
 619
 620                         default:        /* illegal type */
 621                                 errno = EMSGSIZE;
 622                                 return (-1);
 623                         }
 624                 }
 625  next: ;
 626         }
 627         errno = ENOENT;
 628         return (-1);
 629 }