lib/libc/nameser/ns_name.c

   1 /*      $NetBSD: ns_name.c,v 1.7 2009/04/12 17:07:17 christos Exp $     */
   2
   3 /*
   4  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   5  * Copyright (c) 1996,1999 by Internet Software Consortium.
   6  *
   7  * Permission to use, copy, modify, and distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  13  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  17  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 #include <sys/cdefs.h>
  21 #ifndef lint
  22 #ifdef notdef
  23 static const char rcsid[] = "Id: ns_name.c,v 1.11 2009/01/23 19:59:16 each Exp";
  24 #else
  25 __RCSID("$NetBSD: ns_name.c,v 1.7 2009/04/12 17:07:17 christos Exp $");
  26 #endif
  27 #endif
  28
  29 #include "port_before.h"
  30
  31 #include <sys/types.h>
  32
  33 #include <netinet/in.h>
  34 #include <arpa/nameser.h>
  35
  36 #include <errno.h>
  37 #include <resolv.h>
  38 #include <string.h>
  39 #include <ctype.h>
  40 #include <stdlib.h>
  41 #include <limits.h>
  42
  43 #include "port_after.h"
  44
  45 #ifdef SPRINTF_CHAR
  46 # define SPRINTF(x) strlen(sprintf/**/x)
  47 #else
  48 # define SPRINTF(x) ((size_t)sprintf x)
  49 #endif
  50
  51 #define NS_TYPE_ELT                     0x40 /*%< EDNS0 extended label type */
  52 #define DNS_LABELTYPE_BITSTRING         0x41
  53
  54 /* Data. */
  55
  56 static const char       digits[] = "0123456789";
  57
  58 static const char digitvalue[256] = {
  59         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*16*/
  60         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*32*/
  61         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*48*/
  62          0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, /*64*/
  63         -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*80*/
  64         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*96*/
  65         -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*112*/
  66         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*128*/
  67         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  68         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  69         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  70         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  71         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  72         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  73         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  74         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*256*/
  75 };
  76
  77 /* Forward. */
  78
  79 static int              special(int);
  80 static int              printable(int);
  81 static int              dn_find(const u_char *, const u_char *,
  82                                 const u_char * const *,
  83                                 const u_char * const *);
  84 static int              encode_bitsring(const char **, const char *,
  85                                         unsigned char **, unsigned char **,
  86                                         unsigned const char *);
  87 static int              labellen(const u_char *);
  88 static int              decode_bitstring(const unsigned char **,
  89                                          char *, const char *);
  90
  91 /* Public. */
  92
  93 /*%
  94  *      Convert an encoded domain name to printable ascii as per RFC1035.
  95
  96  * return:
  97  *\li   Number of bytes written to buffer, or -1 (with errno set)
  98  *
  99  * notes:
 100  *\li   The root is returned as "."
 101  *\li   All other domains are returned in non absolute form
 102  */
 103 int
 104 ns_name_ntop(const u_char *src, char *dst, size_t dstsiz)
 105 {
 106         const u_char *cp;
 107         char *dn, *eom;
 108         u_char c;
 109         u_int n;
 110         int l;
 111
 112         cp = src;
 113         dn = dst;
 114         eom = dst + dstsiz;
 115
 116         while ((n = *cp++) != 0) {
 117                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 118                         /* Some kind of compression pointer. */
 119                         errno = EMSGSIZE;
 120                         return (-1);
 121                 }
 122                 if (dn != dst) {
 123                         if (dn >= eom) {
 124                                 errno = EMSGSIZE;
 125                                 return (-1);
 126                         }
 127                         *dn++ = '.';
 128                 }
 129                 if ((l = labellen(cp - 1)) < 0) {
 130                         errno = EMSGSIZE; /*%< XXX */
 131                         return (-1);
 132                 }
 133                 if (dn + l >= eom) {
 134                         errno = EMSGSIZE;
 135                         return (-1);
 136                 }
 137                 if ((n & NS_CMPRSFLGS) == NS_TYPE_ELT) {
 138                         int m;
 139
 140                         if (n != DNS_LABELTYPE_BITSTRING) {
 141                                 /* XXX: labellen should reject this case */
 142                                 errno = EINVAL;
 143                                 return (-1);
 144                         }
 145                         if ((m = decode_bitstring(&cp, dn, eom)) < 0)
 146                         {
 147                                 errno = EMSGSIZE;
 148                                 return (-1);
 149                         }
 150                         dn += m;
 151                         continue;
 152                 }
 153                 for (; l > 0; l--) {
 154                         c = *cp++;
 155                         if (special(c)) {
 156                                 if (dn + 1 >= eom) {
 157                                         errno = EMSGSIZE;
 158                                         return (-1);
 159                                 }
 160                                 *dn++ = '\\';
 161                                 *dn++ = (char)c;
 162                         } else if (!printable(c)) {
 163                                 if (dn + 3 >= eom) {
 164                                         errno = EMSGSIZE;
 165                                         return (-1);
 166                                 }
 167                                 *dn++ = '\\';
 168                                 *dn++ = digits[c / 100];
 169                                 *dn++ = digits[(c % 100) / 10];
 170                                 *dn++ = digits[c % 10];
 171                         } else {
 172                                 if (dn >= eom) {
 173                                         errno = EMSGSIZE;
 174                                         return (-1);
 175                                 }
 176                                 *dn++ = (char)c;
 177                         }
 178                 }
 179         }
 180         if (dn == dst) {
 181                 if (dn >= eom) {
 182                         errno = EMSGSIZE;
 183                         return (-1);
 184                 }
 185                 *dn++ = '.';
 186         }
 187         if (dn >= eom) {
 188                 errno = EMSGSIZE;
 189                 return (-1);
 190         }
 191         *dn++ = '\0';
 192         return (dn - dst);
 193 }
 194
 195 /*%
 196  *      Convert a ascii string into an encoded domain name as per RFC1035.
 197  *
 198  * return:
 199  *
 200  *\li   -1 if it fails
 201  *\li   1 if string was fully qualified
 202  *\li   0 is string was not fully qualified
 203  *
 204  * notes:
 205  *\li   Enforces label and domain length limits.
 206  */
 207 int
 208 ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
 209         return (ns_name_pton2(src, dst, dstsiz, NULL));
 210 }
 211
 212 /*
 213  * ns_name_pton2(src, dst, dstsiz, *dstlen)
 214  *      Convert a ascii string into an encoded domain name as per RFC1035.
 215  * return:
 216  *      -1 if it fails
 217  *      1 if string was fully qualified
 218  *      0 is string was not fully qualified
 219  * side effects:
 220  *      fills in *dstlen (if non-NULL)
 221  * notes:
 222  *      Enforces label and domain length limits.
 223  */
 224 int
 225 ns_name_pton2(const char *src, u_char *dst, size_t dstsiz, size_t *dstlen) {
 226         u_char *label, *bp, *eom;
 227         int c, n, escaped, e = 0;
 228         char *cp;
 229
 230         escaped = 0;
 231         bp = dst;
 232         eom = dst + dstsiz;
 233         label = bp++;
 234
 235         while ((c = *src++) != 0) {
 236                 if (escaped) {
 237                         if (c == '[') { /*%< start a bit string label */
 238                                 if ((cp = strchr(src, ']')) == NULL) {
 239                                         errno = EINVAL; /*%< ??? */
 240                                         return (-1);
 241                                 }
 242                                 if ((e = encode_bitsring(&src, cp + 2,
 243                                                          &label, &bp, eom))
 244                                     != 0) {
 245                                         errno = e;
 246                                         return (-1);
 247                                 }
 248                                 escaped = 0;
 249                                 label = bp++;
 250                                 if ((c = *src++) == 0)
 251                                         goto done;
 252                                 else if (c != '.') {
 253                                         errno = EINVAL;
 254                                         return  (-1);
 255                                 }
 256                                 continue;
 257                         }
 258                         else if ((cp = strchr(digits, c)) != NULL) {
 259                                 n = (cp - digits) * 100;
 260                                 if ((c = *src++) == 0 ||
 261                                     (cp = strchr(digits, c)) == NULL) {
 262                                         errno = EMSGSIZE;
 263                                         return (-1);
 264                                 }
 265                                 n += (cp - digits) * 10;
 266                                 if ((c = *src++) == 0 ||
 267                                     (cp = strchr(digits, c)) == NULL) {
 268                                         errno = EMSGSIZE;
 269                                         return (-1);
 270                                 }
 271                                 n += (cp - digits);
 272                                 if (n > 255) {
 273                                         errno = EMSGSIZE;
 274                                         return (-1);
 275                                 }
 276                                 c = n;
 277                         }
 278                         escaped = 0;
 279                 } else if (c == '\\') {
 280                         escaped = 1;
 281                         continue;
 282                 } else if (c == '.') {
 283                         c = (bp - label - 1);
 284                         if ((c & NS_CMPRSFLGS) != 0) {  /*%< Label too big. */
 285                                 errno = EMSGSIZE;
 286                                 return (-1);
 287                         }
 288                         if (label >= eom) {
 289                                 errno = EMSGSIZE;
 290                                 return (-1);
 291                         }
 292                         *label = c;
 293                         /* Fully qualified ? */
 294                         if (*src == '\0') {
 295                                 if (c != 0) {
 296                                         if (bp >= eom) {
 297                                                 errno = EMSGSIZE;
 298                                                 return (-1);
 299                                         }
 300                                         *bp++ = '\0';
 301                                 }
 302                                 if ((bp - dst) > MAXCDNAME) {
 303                                         errno = EMSGSIZE;
 304                                         return (-1);
 305                                 }
 306                                 if (dstlen != NULL)
 307                                         *dstlen = (bp - dst);
 308                                 return (1);
 309                         }
 310                         if (c == 0 || *src == '.') {
 311                                 errno = EMSGSIZE;
 312                                 return (-1);
 313                         }
 314                         label = bp++;
 315                         continue;
 316                 }
 317                 if (bp >= eom) {
 318                         errno = EMSGSIZE;
 319                         return (-1);
 320                 }
 321                 *bp++ = (u_char)c;
 322         }
 323         c = (bp - label - 1);
 324         if ((c & NS_CMPRSFLGS) != 0) {          /*%< Label too big. */
 325                 errno = EMSGSIZE;
 326                 return (-1);
 327         }
 328   done:
 329         if (label >= eom) {
 330                 errno = EMSGSIZE;
 331                 return (-1);
 332         }
 333         *label = c;
 334         if (c != 0) {
 335                 if (bp >= eom) {
 336                         errno = EMSGSIZE;
 337                         return (-1);
 338                 }
 339                 *bp++ = 0;
 340         }
 341         if ((bp - dst) > MAXCDNAME) {   /*%< src too big */
 342                 errno = EMSGSIZE;
 343                 return (-1);
 344         }
 345         if (dstlen != NULL)
 346                 *dstlen = (bp - dst);
 347         return (0);
 348 }
 349
 350 /*%
 351  *      Convert a network strings labels into all lowercase.
 352  *
 353  * return:
 354  *\li   Number of bytes written to buffer, or -1 (with errno set)
 355  *
 356  * notes:
 357  *\li   Enforces label and domain length limits.
 358  */
 359
 360 int
 361 ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz)
 362 {
 363         const u_char *cp;
 364         u_char *dn, *eom;
 365         u_char c;
 366         u_int n;
 367         int l;
 368
 369         cp = src;
 370         dn = dst;
 371         eom = dst + dstsiz;
 372
 373         if (dn >= eom) {
 374                 errno = EMSGSIZE;
 375                 return (-1);
 376         }
 377         while ((n = *cp++) != 0) {
 378                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 379                         /* Some kind of compression pointer. */
 380                         errno = EMSGSIZE;
 381                         return (-1);
 382                 }
 383                 *dn++ = n;
 384                 if ((l = labellen(cp - 1)) < 0) {
 385                         errno = EMSGSIZE;
 386                         return (-1);
 387                 }
 388                 if (dn + l >= eom) {
 389                         errno = EMSGSIZE;
 390                         return (-1);
 391                 }
 392                 for (; l > 0; l--) {
 393                         c = *cp++;
 394                         if (isascii(c) && isupper(c))
 395                                 *dn++ = tolower(c);
 396                         else
 397                                 *dn++ = c;
 398                 }
 399         }
 400         *dn++ = '\0';
 401         return (dn - dst);
 402 }
 403
 404 /*%
 405  *      Unpack a domain name from a message, source may be compressed.
 406  *
 407  * return:
 408  *\li   -1 if it fails, or consumed octets if it succeeds.
 409  */
 410 int
 411 ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
 412                u_char *dst, size_t dstsiz)
 413 {
 414         return (ns_name_unpack2(msg, eom, src, dst, dstsiz, NULL));
 415 }
 416
 417 /*
 418  * ns_name_unpack2(msg, eom, src, dst, dstsiz, *dstlen)
 419  *      Unpack a domain name from a message, source may be compressed.
 420  * return:
 421  *      -1 if it fails, or consumed octets if it succeeds.
 422  * side effect:
 423  *      fills in *dstlen (if non-NULL).
 424  */
 425 int
 426 ns_name_unpack2(const u_char *msg, const u_char *eom, const u_char *src,
 427                 u_char *dst, size_t dstsiz, size_t *dstlen)
 428 {
 429         const u_char *srcp, *dstlim;
 430         u_char *dstp;
 431         int n, len, checked, l;
 432
 433         len = -1;
 434         checked = 0;
 435         dstp = dst;
 436         srcp = src;
 437         dstlim = dst + dstsiz;
 438         if (srcp < msg || srcp >= eom) {
 439                 errno = EMSGSIZE;
 440                 return (-1);
 441         }
 442         /* Fetch next label in domain name. */
 443         while ((n = *srcp++) != 0) {
 444                 /* Check for indirection. */
 445                 switch (n & NS_CMPRSFLGS) {
 446                 case 0:
 447                 case NS_TYPE_ELT:
 448                         /* Limit checks. */
 449                         if ((l = labellen(srcp - 1)) < 0) {
 450                                 errno = EMSGSIZE;
 451                                 return (-1);
 452                         }
 453                         if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
 454                                 errno = EMSGSIZE;
 455                                 return (-1);
 456                         }
 457                         checked += l + 1;
 458                         *dstp++ = n;
 459                         memcpy(dstp, srcp, (size_t)l);
 460                         dstp += l;
 461                         srcp += l;
 462                         break;
 463
 464                 case NS_CMPRSFLGS:
 465                         if (srcp >= eom) {
 466                                 errno = EMSGSIZE;
 467                                 return (-1);
 468                         }
 469                         if (len < 0)
 470                                 len = srcp - src + 1;
 471                         srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
 472                         if (srcp < msg || srcp >= eom) {  /*%< Out of range. */
 473                                 errno = EMSGSIZE;
 474                                 return (-1);
 475                         }
 476                         checked += 2;
 477                         /*
 478                          * Check for loops in the compressed name;
 479                          * if we've looked at the whole message,
 480                          * there must be a loop.
 481                          */
 482                         if (checked >= eom - msg) {
 483                                 errno = EMSGSIZE;
 484                                 return (-1);
 485                         }
 486                         break;
 487
 488                 default:
 489                         errno = EMSGSIZE;
 490                         return (-1);                    /*%< flag error */
 491                 }
 492         }
 493         *dstp++ = 0;
 494         if (dstlen != NULL)
 495                 *dstlen = dstp - dst;
 496         if (len < 0)
 497                 len = srcp - src;
 498         return (len);
 499 }
 500
 501 /*%
 502  *      Pack domain name 'domain' into 'comp_dn'.
 503  *
 504  * return:
 505  *\li   Size of the compressed name, or -1.
 506  *
 507  * notes:
 508  *\li   'dnptrs' is an array of pointers to previous compressed names.
 509  *\li   dnptrs[0] is a pointer to the beginning of the message. The array
 510  *      ends with NULL.
 511  *\li   'lastdnptr' is a pointer to the end of the array pointed to
 512  *      by 'dnptrs'.
 513  *
 514  * Side effects:
 515  *\li   The list of pointers in dnptrs is updated for labels inserted into
 516  *      the message as we compress the name.  If 'dnptr' is NULL, we don't
 517  *      try to compress names. If 'lastdnptr' is NULL, we don't update the
 518  *      list.
 519  */
 520 int
 521 ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
 522              const u_char **dnptrs, const u_char **lastdnptr)
 523 {
 524         u_char *dstp;
 525         const u_char **cpp, **lpp, *eob, *msg;
 526         const u_char *srcp;
 527         int n, l, first = 1;
 528
 529         srcp = src;
 530         dstp = dst;
 531         eob = dstp + dstsiz;
 532         lpp = cpp = NULL;
 533         if (dnptrs != NULL) {
 534                 if ((msg = *dnptrs++) != NULL) {
 535                         for (cpp = dnptrs; *cpp != NULL; cpp++)
 536                                 continue;
 537                         lpp = cpp;      /*%< end of list to search */
 538                 }
 539         } else
 540                 msg = NULL;
 541
 542         /* make sure the domain we are about to add is legal */
 543         l = 0;
 544         do {
 545                 int l0;
 546
 547                 n = *srcp;
 548                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 549                         errno = EMSGSIZE;
 550                         return (-1);
 551                 }
 552                 if ((l0 = labellen(srcp)) < 0) {
 553                         errno = EINVAL;
 554                         return (-1);
 555                 }
 556                 l += l0 + 1;
 557                 if (l > MAXCDNAME) {
 558                         errno = EMSGSIZE;
 559                         return (-1);
 560                 }
 561                 srcp += l0 + 1;
 562         } while (n != 0);
 563
 564         /* from here on we need to reset compression pointer array on error */
 565         srcp = src;
 566         do {
 567                 /* Look to see if we can use pointers. */
 568                 n = *srcp;
 569                 if (n != 0 && msg != NULL) {
 570                         l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
 571                                     (const u_char * const *)lpp);
 572                         if (l >= 0) {
 573                                 if (dstp + 1 >= eob) {
 574                                         goto cleanup;
 575                                 }
 576                                 *dstp++ = ((u_int32_t)l >> 8) | NS_CMPRSFLGS;
 577                                 *dstp++ = l % 256;
 578                                 return (dstp - dst);
 579                         }
 580                         /* Not found, save it. */
 581                         if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
 582                             (dstp - msg) < 0x4000 && first) {
 583                                 *cpp++ = dstp;
 584                                 *cpp = NULL;
 585                                 first = 0;
 586                         }
 587                 }
 588                 /* copy label to buffer */
 589                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 590                         /* Should not happen. */
 591                         goto cleanup;
 592                 }
 593                 n = labellen(srcp);
 594                 if (dstp + 1 + n >= eob) {
 595                         goto cleanup;
 596                 }
 597                 memcpy(dstp, srcp, (size_t)(n + 1));
 598                 srcp += n + 1;
 599                 dstp += n + 1;
 600         } while (n != 0);
 601
 602         if (dstp > eob) {
 603 cleanup:
 604                 if (msg != NULL)
 605                         *lpp = NULL;
 606                 errno = EMSGSIZE;
 607                 return (-1);
 608         }
 609         return (dstp - dst);
 610 }
 611
 612 /*%
 613  *      Expand compressed domain name to presentation format.
 614  *
 615  * return:
 616  *\li   Number of bytes read out of `src', or -1 (with errno set).
 617  *
 618  * note:
 619  *\li   Root domain returns as "." not "".
 620  */
 621 int
 622 ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
 623                    char *dst, size_t dstsiz)
 624 {
 625         u_char tmp[NS_MAXCDNAME];
 626         int n;
 627
 628         if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
 629                 return (-1);
 630         if (ns_name_ntop(tmp, dst, dstsiz) == -1)
 631                 return (-1);
 632         return (n);
 633 }
 634
 635 /*%
 636  *      Compress a domain name into wire format, using compression pointers.
 637  *
 638  * return:
 639  *\li   Number of bytes consumed in `dst' or -1 (with errno set).
 640  *
 641  * notes:
 642  *\li   'dnptrs' is an array of pointers to previous compressed names.
 643  *\li   dnptrs[0] is a pointer to the beginning of the message.
 644  *\li   The list ends with NULL.  'lastdnptr' is a pointer to the end of the
 645  *      array pointed to by 'dnptrs'. Side effect is to update the list of
 646  *      pointers for labels inserted into the message as we compress the name.
 647  *\li   If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
 648  *      is NULL, we don't update the list.
 649  */
 650 int
 651 ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
 652                  const u_char **dnptrs, const u_char **lastdnptr)
 653 {
 654         u_char tmp[NS_MAXCDNAME];
 655
 656         if (ns_name_pton(src, tmp, sizeof tmp) == -1)
 657                 return (-1);
 658         return (ns_name_pack(tmp, dst, (int)dstsiz, dnptrs, lastdnptr));
 659 }
 660
 661 /*%
 662  * Reset dnptrs so that there are no active references to pointers at or
 663  * after src.
 664  */
 665 void
 666 ns_name_rollback(const u_char *src, const u_char **dnptrs,
 667                  const u_char **lastdnptr)
 668 {
 669         while (dnptrs < lastdnptr && *dnptrs != NULL) {
 670                 if (*dnptrs >= src) {
 671                         *dnptrs = NULL;
 672                         break;
 673                 }
 674                 dnptrs++;
 675         }
 676 }
 677
 678 /*%
 679  *      Advance *ptrptr to skip over the compressed name it points at.
 680  *
 681  * return:
 682  *\li   0 on success, -1 (with errno set) on failure.
 683  */
 684 int
 685 ns_name_skip(const u_char **ptrptr, const u_char *eom)
 686 {
 687         const u_char *cp;
 688         u_int n;
 689         int l;
 690
 691         cp = *ptrptr;
 692         while (cp < eom && (n = *cp++) != 0) {
 693                 /* Check for indirection. */
 694                 switch (n & NS_CMPRSFLGS) {
 695                 case 0:                 /*%< normal case, n == len */
 696                         cp += n;
 697                         continue;
 698                 case NS_TYPE_ELT: /*%< EDNS0 extended label */
 699                         if ((l = labellen(cp - 1)) < 0) {
 700                                 errno = EMSGSIZE; /*%< XXX */
 701                                 return (-1);
 702                         }
 703                         cp += l;
 704                         continue;
 705                 case NS_CMPRSFLGS:      /*%< indirection */
 706                         cp++;
 707                         break;
 708                 default:                /*%< illegal type */
 709                         errno = EMSGSIZE;
 710                         return (-1);
 711                 }
 712                 break;
 713         }
 714         if (cp > eom) {
 715                 errno = EMSGSIZE;
 716                 return (-1);
 717         }
 718         *ptrptr = cp;
 719         return (0);
 720 }
 721
 722 /* Find the number of octets an nname takes up, including the root label.
 723  * (This is basically ns_name_skip() without compression-pointer support.)
 724  * ((NOTE: can only return zero if passed-in namesiz argument is zero.))
 725  */
 726 ssize_t
 727 ns_name_length(ns_nname_ct nname, size_t namesiz) {
 728         ns_nname_ct orig = nname;
 729         u_int n;
 730
 731         while (namesiz-- > 0 && (n = *nname++) != 0) {
 732                 if ((n & NS_CMPRSFLGS) != 0) {
 733                         errno = EISDIR;
 734                         return (-1);
 735                 }
 736                 if (n > namesiz) {
 737                         errno = EMSGSIZE;
 738                         return (-1);
 739                 }
 740                 nname += n;
 741                 namesiz -= n;
 742         }
 743         return (nname - orig);
 744 }
 745
 746 /* Compare two nname's for equality.  Return -1 on error (setting errno).
 747  */
 748 int
 749 ns_name_eq(ns_nname_ct a, size_t as, ns_nname_ct b, size_t bs) {
 750         ns_nname_ct ae = a + as, be = b + bs;
 751         int ac, bc;
 752
 753         while (ac = *a, bc = *b, ac != 0 && bc != 0) {
 754                 if ((ac & NS_CMPRSFLGS) != 0 || (bc & NS_CMPRSFLGS) != 0) {
 755                         errno = EISDIR;
 756                         return (-1);
 757                 }
 758                 if (a + ac >= ae || b + bc >= be) {
 759                         errno = EMSGSIZE;
 760                         return (-1);
 761                 }
 762                 if (ac != bc || strncasecmp((const char *) ++a,
 763                                             (const char *) ++b,
 764                                             (size_t)ac) != 0)
 765                         return (0);
 766                 a += ac, b += bc;
 767         }
 768         return (ac == 0 && bc == 0);
 769 }
 770
 771 /* Is domain "A" owned by (at or below) domain "B"?
 772  */
 773 int
 774 ns_name_owned(ns_namemap_ct a, int an, ns_namemap_ct b, int bn) {
 775         /* If A is shorter, it cannot be owned by B. */
 776         if (an < bn)
 777                 return (0);
 778
 779         /* If they are unequal before the length of the shorter, A cannot... */
 780         while (bn > 0) {
 781                 if (a->len != b->len ||
 782                     strncasecmp((const char *) a->base,
 783                                 (const char *) b->base, (size_t)a->len) != 0)
 784                         return (0);
 785                 a++, an--;
 786                 b++, bn--;
 787         }
 788
 789         /* A might be longer or not, but either way, B owns it. */
 790         return (1);
 791 }
 792
 793 /* Build an array of <base,len> tuples from an nname, top-down order.
 794  * Return the number of tuples (labels) thus discovered.
 795  */
 796 int
 797 ns_name_map(ns_nname_ct nname, size_t namelen, ns_namemap_t map, int mapsize) {
 798         u_int n;
 799         int l;
 800
 801         n = *nname++;
 802         namelen--;
 803
 804         /* Root zone? */
 805         if (n == 0) {
 806                 /* Extra data follows name? */
 807                 if (namelen > 0) {
 808                         errno = EMSGSIZE;
 809                         return (-1);
 810                 }
 811                 return (0);
 812         }
 813
 814         /* Compression pointer? */
 815         if ((n & NS_CMPRSFLGS) != 0) {
 816                 errno = EISDIR;
 817                 return (-1);
 818         }
 819
 820         /* Label too long? */
 821         if (n > namelen) {
 822                 errno = EMSGSIZE;
 823                 return (-1);
 824         }
 825
 826         /* Recurse to get rest of name done first. */
 827         l = ns_name_map(nname + n, namelen - n, map, mapsize);
 828         if (l < 0)
 829                 return (-1);
 830
 831         /* Too many labels? */
 832         if (l >= mapsize) {
 833                 errno = ENAMETOOLONG;
 834                 return (-1);
 835         }
 836
 837         /* We're on our way back up-stack, store current map data. */
 838         map[l].base = nname;
 839         map[l].len = n;
 840         return (l + 1);
 841 }
 842
 843 /* Count the labels in a domain name.  Root counts, so COM. has two.  This
 844  * is to make the result comparable to the result of ns_name_map().
 845  */
 846 int
 847 ns_name_labels(ns_nname_ct nname, size_t namesiz) {
 848         int ret = 0;
 849         u_int n;
 850
 851         while (namesiz-- > 0 && (n = *nname++) != 0) {
 852                 if ((n & NS_CMPRSFLGS) != 0) {
 853                         errno = EISDIR;
 854                         return (-1);
 855                 }
 856                 if (n > namesiz) {
 857                         errno = EMSGSIZE;
 858                         return (-1);
 859                 }
 860                 nname += n;
 861                 namesiz -= n;
 862                 ret++;
 863         }
 864         return (ret + 1);
 865 }
 866
 867 /* Private. */
 868
 869 /*%
 870  *      Thinking in noninternationalized USASCII (per the DNS spec),
 871  *      is this characted special ("in need of quoting") ?
 872  *
 873  * return:
 874  *\li   boolean.
 875  */
 876 static int
 877 special(int ch) {
 878         switch (ch) {
 879         case 0x22: /*%< '"' */
 880         case 0x2E: /*%< '.' */
 881         case 0x3B: /*%< ';' */
 882         case 0x5C: /*%< '\\' */
 883         case 0x28: /*%< '(' */
 884         case 0x29: /*%< ')' */
 885         /* Special modifiers in zone files. */
 886         case 0x40: /*%< '@' */
 887         case 0x24: /*%< '$' */
 888                 return (1);
 889         default:
 890                 return (0);
 891         }
 892 }
 893
 894 /*%
 895  *      Thinking in noninternationalized USASCII (per the DNS spec),
 896  *      is this character visible and not a space when printed ?
 897  *
 898  * return:
 899  *\li   boolean.
 900  */
 901 static int
 902 printable(int ch) {
 903         return (ch > 0x20 && ch < 0x7f);
 904 }
 905
 906 /*%
 907  *      Thinking in noninternationalized USASCII (per the DNS spec),
 908  *      convert this character to lower case if it's upper case.
 909  */
 910 static int
 911 mklower(int ch) {
 912         if (ch >= 0x41 && ch <= 0x5A)
 913                 return (ch + 0x20);
 914         return (ch);
 915 }
 916
 917 /*%
 918  *      Search for the counted-label name in an array of compressed names.
 919  *
 920  * return:
 921  *\li   offset from msg if found, or -1.
 922  *
 923  * notes:
 924  *\li   dnptrs is the pointer to the first name on the list,
 925  *\li   not the pointer to the start of the message.
 926  */
 927 static int
 928 dn_find(const u_char *domain, const u_char *msg,
 929         const u_char * const *dnptrs,
 930         const u_char * const *lastdnptr)
 931 {
 932         const u_char *dn, *cp, *sp;
 933         const u_char * const *cpp;
 934         u_int n;
 935
 936         for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
 937                 sp = *cpp;
 938                 /*
 939                  * terminate search on:
 940                  * root label
 941                  * compression pointer
 942                  * unusable offset
 943                  */
 944                 while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
 945                        (sp - msg) < 0x4000) {
 946                         dn = domain;
 947                         cp = sp;
 948                         while ((n = *cp++) != 0) {
 949                                 /*
 950                                  * check for indirection
 951                                  */
 952                                 switch (n & NS_CMPRSFLGS) {
 953                                 case 0:         /*%< normal case, n == len */
 954                                         n = labellen(cp - 1); /*%< XXX */
 955                                         if (n != *dn++)
 956                                                 goto next;
 957
 958                                         for (; n > 0; n--)
 959                                                 if (mklower(*dn++) !=
 960                                                     mklower(*cp++))
 961                                                         goto next;
 962                                         /* Is next root for both ? */
 963                                         if (*dn == '\0' && *cp == '\0')
 964                                                 return (sp - msg);
 965                                         if (*dn)
 966                                                 continue;
 967                                         goto next;
 968                                 case NS_CMPRSFLGS:      /*%< indirection */
 969                                         cp = msg + (((n & 0x3f) << 8) | *cp);
 970                                         break;
 971
 972                                 default:        /*%< illegal type */
 973                                         errno = EMSGSIZE;
 974                                         return (-1);
 975                                 }
 976                         }
 977  next: ;
 978                         sp += *sp + 1;
 979                 }
 980         }
 981         errno = ENOENT;
 982         return (-1);
 983 }
 984
 985 static int
 986 decode_bitstring(const unsigned char **cpp, char *dn, const char *eom)
 987 {
 988         const unsigned char *cp = *cpp;
 989         char *beg = dn, tc;
 990         int b, blen, plen, i;
 991
 992         if ((blen = (*cp & 0xff)) == 0)
 993                 blen = 256;
 994         plen = (blen + 3) / 4;
 995         plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
 996         if (dn + plen >= eom)
 997                 return (-1);
 998
 999         cp++;
1000         i = SPRINTF((dn, "\\[x"));
1001         if (i < 0)
1002                 return (-1);
1003         dn += i;
1004         for (b = blen; b > 7; b -= 8, cp++) {
1005                 i = SPRINTF((dn, "%02x", *cp & 0xff));
1006                 if (i < 0)
1007                         return (-1);
1008                 dn += i;
1009         }
1010         if (b > 4) {
1011                 tc = *cp++;
1012                 i = SPRINTF((dn, "%02x", tc & (0xff << (8 - b))));
1013                 if (i < 0)
1014                         return (-1);
1015                 dn += i;
1016         } else if (b > 0) {
1017                 tc = *cp++;
1018                 i = SPRINTF((dn, "%1x",
1019                                (((u_int32_t)tc >> 4) & 0x0f) & (0x0f << (4 - b))));
1020                 if (i < 0)
1021                         return (-1);
1022                 dn += i;
1023         }
1024         i = SPRINTF((dn, "/%d]", blen));
1025         if (i < 0)
1026                 return (-1);
1027         dn += i;
1028
1029         *cpp = cp;
1030         return (dn - beg);
1031 }
1032
1033 static int
1034 encode_bitsring(const char **bp, const char *end, unsigned char **labelp,
1035                 unsigned char ** dst, unsigned const char *eom)
1036 {
1037         int afterslash = 0;
1038         const char *cp = *bp;
1039         unsigned char *tp;
1040         char c;
1041         const char *beg_blen;
1042         char *end_blen = NULL;
1043         int value = 0, count = 0, tbcount = 0, blen = 0;
1044
1045         beg_blen = end_blen = NULL;
1046
1047         /* a bitstring must contain at least 2 characters */
1048         if (end - cp < 2)
1049                 return (EINVAL);
1050
1051         /* XXX: currently, only hex strings are supported */
1052         if (*cp++ != 'x')
1053                 return (EINVAL);
1054         if (!isxdigit((*cp) & 0xff)) /*%< reject '\[x/BLEN]' */
1055                 return (EINVAL);
1056
1057         for (tp = *dst + 1; cp < end && tp < eom; cp++) {
1058                 switch((c = *cp)) {
1059                 case ']':       /*%< end of the bitstring */
1060                         if (afterslash) {
1061                                 if (beg_blen == NULL)
1062                                         return (EINVAL);
1063                                 blen = (int)strtol(beg_blen, &end_blen, 10);
1064                                 if (*end_blen != ']')
1065                                         return (EINVAL);
1066                         }
1067                         if (count)
1068                                 *tp++ = ((value << 4) & 0xff);
1069                         cp++;   /*%< skip ']' */
1070                         goto done;
1071                 case '/':
1072                         afterslash = 1;
1073                         break;
1074                 default:
1075                         if (afterslash) {
1076                                 if (!isdigit(c&0xff))
1077                                         return (EINVAL);
1078                                 if (beg_blen == NULL) {
1079
1080                                         if (c == '0') {
1081                                                 /* blen never begings with 0 */
1082                                                 return (EINVAL);
1083                                         }
1084                                         beg_blen = cp;
1085                                 }
1086                         } else {
1087                                 if (!isxdigit(c&0xff))
1088                                         return (EINVAL);
1089                                 value <<= 4;
1090                                 value += digitvalue[(int)c];
1091                                 count += 4;
1092                                 tbcount += 4;
1093                                 if (tbcount > 256)
1094                                         return (EINVAL);
1095                                 if (count == 8) {
1096                                         *tp++ = value;
1097                                         count = 0;
1098                                 }
1099                         }
1100                         break;
1101                 }
1102         }
1103   done:
1104         if (cp >= end || tp >= eom)
1105                 return (EMSGSIZE);
1106
1107         /*
1108          * bit length validation:
1109          * If a <length> is present, the number of digits in the <bit-data>
1110          * MUST be just sufficient to contain the number of bits specified
1111          * by the <length>. If there are insignificant bits in a final
1112          * hexadecimal or octal digit, they MUST be zero.
1113          * RFC2673, Section 3.2.
1114          */
1115         if (blen > 0) {
1116                 int traillen;
1117
1118                 if (((blen + 3) & ~3) != tbcount)
1119                         return (EINVAL);
1120                 traillen = tbcount - blen; /*%< between 0 and 3 */
1121                 if (((value << (8 - traillen)) & 0xff) != 0)
1122                         return (EINVAL);
1123         }
1124         else
1125                 blen = tbcount;
1126         if (blen == 256)
1127                 blen = 0;
1128
1129         /* encode the type and the significant bit fields */
1130         **labelp = DNS_LABELTYPE_BITSTRING;
1131         **dst = blen;
1132
1133         *bp = cp;
1134         *dst = tp;
1135
1136         return (0);
1137 }
1138
1139 static int
1140 labellen(const u_char *lp)
1141 {
1142         int bitlen;
1143         u_char l = *lp;
1144
1145         if ((l & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
1146                 /* should be avoided by the caller */
1147                 return (-1);
1148         }
1149
1150         if ((l & NS_CMPRSFLGS) == NS_TYPE_ELT) {
1151                 if (l == DNS_LABELTYPE_BITSTRING) {
1152                         if ((bitlen = *(lp + 1)) == 0)
1153                                 bitlen = 256;
1154                         return ((bitlen + 7 ) / 8 + 1);
1155                 }
1156                 return (-1);    /*%< unknwon ELT */
1157         }
1158         return (l);
1159 }
1160
1161 /*! \file */