lib/libc/net/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  * $FreeBSD: src/lib/libc/net/ns_name.c,v 1.2 1999/08/28 00:00:14 peter Exp $
  18  * $DragonFly: src/lib/libc/net/ns_name.c,v 1.3 2005/11/13 02:04:47 swildner Exp $
  19  */
  20
  21 #include <sys/types.h>
  22
  23 #include <netinet/in.h>
  24 #include <arpa/nameser.h>
  25
  26 #include <errno.h>
  27 #include <resolv.h>
  28 #include <string.h>
  29
  30 /* Data. */
  31
  32 static char             digits[] = "0123456789";
  33
  34 /* Forward. */
  35
  36 static int              special(int);
  37 static int              printable(int);
  38 static int              dn_find(const u_char *, const u_char *,
  39                                 const u_char * const *,
  40                                 const u_char * const *);
  41
  42 /* Public. */
  43
  44 /*
  45  * ns_name_ntop(src, dst, dstsiz)
  46  *      Convert an encoded domain name to printable ascii as per RFC1035.
  47  * return:
  48  *      Number of bytes written to buffer, or -1 (with errno set)
  49  * notes:
  50  *      The root is returned as "."
  51  *      All other domains are returned in non absolute form
  52  */
  53 int
  54 ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) {
  55         const u_char *cp;
  56         char *dn, *eom;
  57         u_char c;
  58         u_int n;
  59
  60         cp = src;
  61         dn = dst;
  62         eom = dst + dstsiz;
  63
  64         while ((n = *cp++) != 0) {
  65                 if ((n & NS_CMPRSFLGS) != 0) {
  66                         /* Some kind of compression pointer. */
  67                         errno = EMSGSIZE;
  68                         return (-1);
  69                 }
  70                 if (dn != dst) {
  71                         if (dn >= eom) {
  72                                 errno = EMSGSIZE;
  73                                 return (-1);
  74                         }
  75                         *dn++ = '.';
  76                 }
  77                 if (dn + n >= eom) {
  78                         errno = EMSGSIZE;
  79                         return (-1);
  80                 }
  81                 for (; n > 0; n--) {
  82                         c = *cp++;
  83                         if (special(c)) {
  84                                 if (dn + 1 >= eom) {
  85                                         errno = EMSGSIZE;
  86                                         return (-1);
  87                                 }
  88                                 *dn++ = '\\';
  89                                 *dn++ = (char)c;
  90                         } else if (!printable(c)) {
  91                                 if (dn + 3 >= eom) {
  92                                         errno = EMSGSIZE;
  93                                         return (-1);
  94                                 }
  95                                 *dn++ = '\\';
  96                                 *dn++ = digits[c / 100];
  97                                 *dn++ = digits[(c % 100) / 10];
  98                                 *dn++ = digits[c % 10];
  99                         } else {
 100                                 if (dn >= eom) {
 101                                         errno = EMSGSIZE;
 102                                         return (-1);
 103                                 }
 104                                 *dn++ = (char)c;
 105                         }
 106                 }
 107         }
 108         if (dn == dst) {
 109                 if (dn >= eom) {
 110                         errno = EMSGSIZE;
 111                         return (-1);
 112                 }
 113                 *dn++ = '.';
 114         }
 115         if (dn >= eom) {
 116                 errno = EMSGSIZE;
 117                 return (-1);
 118         }
 119         *dn++ = '\0';
 120         return (dn - dst);
 121 }
 122
 123 /*
 124  * ns_name_pton(src, dst, dstsiz)
 125  *      Convert a ascii string into an encoded domain name as per RFC1035.
 126  * return:
 127  *      -1 if it fails
 128  *      1 if string was fully qualified
 129  *      0 is string was not fully qualified
 130  * notes:
 131  *      Enforces label and domain length limits.
 132  */
 133
 134 int
 135 ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
 136         u_char *label, *bp, *eom;
 137         int c, n, escaped;
 138         char *cp;
 139
 140         escaped = 0;
 141         bp = dst;
 142         eom = dst + dstsiz;
 143         label = bp++;
 144
 145         while ((c = *src++) != 0) {
 146                 if (escaped) {
 147                         if ((cp = strchr(digits, c)) != NULL) {
 148                                 n = (cp - digits) * 100;
 149                                 if ((c = *src++) == 0 ||
 150                                     (cp = strchr(digits, c)) == NULL) {
 151                                         errno = EMSGSIZE;
 152                                         return (-1);
 153                                 }
 154                                 n += (cp - digits) * 10;
 155                                 if ((c = *src++) == 0 ||
 156                                     (cp = strchr(digits, c)) == NULL) {
 157                                         errno = EMSGSIZE;
 158                                         return (-1);
 159                                 }
 160                                 n += (cp - digits);
 161                                 if (n > 255) {
 162                                         errno = EMSGSIZE;
 163                                         return (-1);
 164                                 }
 165                                 c = n;
 166                         }
 167                         escaped = 0;
 168                 } else if (c == '\\') {
 169                         escaped = 1;
 170                         continue;
 171                 } else if (c == '.') {
 172                         c = (bp - label - 1);
 173                         if ((c & NS_CMPRSFLGS) != 0) {  /* Label too big. */
 174                                 errno = EMSGSIZE;
 175                                 return (-1);
 176                         }
 177                         if (label >= eom) {
 178                                 errno = EMSGSIZE;
 179                                 return (-1);
 180                         }
 181                         *label = c;
 182                         /* Fully qualified ? */
 183                         if (*src == '\0') {
 184                                 if (c != 0) {
 185                                         if (bp >= eom) {
 186                                                 errno = EMSGSIZE;
 187                                                 return (-1);
 188                                         }
 189                                         *bp++ = '\0';
 190                                 }
 191                                 if ((bp - dst) > MAXCDNAME) {
 192                                         errno = EMSGSIZE;
 193                                         return (-1);
 194                                 }
 195                                 return (1);
 196                         }
 197                         if (c == 0) {
 198                                 errno = EMSGSIZE;
 199                                 return (-1);
 200                         }
 201                         label = bp++;
 202                         continue;
 203                 }
 204                 if (bp >= eom) {
 205                         errno = EMSGSIZE;
 206                         return (-1);
 207                 }
 208                 *bp++ = (u_char)c;
 209         }
 210         c = (bp - label - 1);
 211         if ((c & NS_CMPRSFLGS) != 0) {          /* Label too big. */
 212                 errno = EMSGSIZE;
 213                 return (-1);
 214         }
 215         if (label >= eom) {
 216                 errno = EMSGSIZE;
 217                 return (-1);
 218         }
 219         *label = c;
 220         if (c != 0) {
 221                 if (bp >= eom) {
 222                         errno = EMSGSIZE;
 223                         return (-1);
 224                 }
 225                 *bp++ = 0;
 226         }
 227         if ((bp - dst) > MAXCDNAME) {   /* src too big */
 228                 errno = EMSGSIZE;
 229                 return (-1);
 230         }
 231         return (0);
 232 }
 233
 234 /*
 235  * ns_name_unpack(msg, eom, src, dst, dstsiz)
 236  *      Unpack a domain name from a message, source may be compressed.
 237  * return:
 238  *      -1 if it fails, or consumed octets if it succeeds.
 239  */
 240 int
 241 ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
 242                u_char *dst, size_t dstsiz)
 243 {
 244         const u_char *srcp, *dstlim;
 245         u_char *dstp;
 246         int n, len, checked;
 247
 248         len = -1;
 249         checked = 0;
 250         dstp = dst;
 251         srcp = src;
 252         dstlim = dst + dstsiz;
 253         if (srcp < msg || srcp >= eom) {
 254                 errno = EMSGSIZE;
 255                 return (-1);
 256         }
 257         /* Fetch next label in domain name. */
 258         while ((n = *srcp++) != 0) {
 259                 /* Check for indirection. */
 260                 switch (n & NS_CMPRSFLGS) {
 261                 case 0:
 262                         /* Limit checks. */
 263                         if (dstp + n + 1 >= dstlim || srcp + n >= eom) {
 264                                 errno = EMSGSIZE;
 265                                 return (-1);
 266                         }
 267                         checked += n + 1;
 268                         *dstp++ = n;
 269                         memcpy(dstp, srcp, n);
 270                         dstp += n;
 271                         srcp += n;
 272                         break;
 273
 274                 case NS_CMPRSFLGS:
 275                         if (srcp >= eom) {
 276                                 errno = EMSGSIZE;
 277                                 return (-1);
 278                         }
 279                         if (len < 0)
 280                                 len = srcp - src + 1;
 281                         srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
 282                         if (srcp < msg || srcp >= eom) {  /* Out of range. */
 283                                 errno = EMSGSIZE;
 284                                 return (-1);
 285                         }
 286                         checked += 2;
 287                         /*
 288                          * Check for loops in the compressed name;
 289                          * if we've looked at the whole message,
 290                          * there must be a loop.
 291                          */
 292                         if (checked >= eom - msg) {
 293                                 errno = EMSGSIZE;
 294                                 return (-1);
 295                         }
 296                         break;
 297
 298                 default:
 299                         errno = EMSGSIZE;
 300                         return (-1);                    /* flag error */
 301                 }
 302         }
 303         *dstp = '\0';
 304         if (len < 0)
 305                 len = srcp - src;
 306         return (len);
 307 }
 308
 309 /*
 310  * ns_name_pack(src, dst, dstsiz, dnptrs, lastdnptr)
 311  *      Pack domain name 'domain' into 'comp_dn'.
 312  * return:
 313  *      Size of the compressed name, or -1.
 314  * notes:
 315  *      'dnptrs' is an array of pointers to previous compressed names.
 316  *      dnptrs[0] is a pointer to the beginning of the message. The array
 317  *      ends with NULL.
 318  *      'lastdnptr' is a pointer to the end of the array pointed to
 319  *      by 'dnptrs'.
 320  * Side effects:
 321  *      The list of pointers in dnptrs is updated for labels inserted into
 322  *      the message as we compress the name.  If 'dnptr' is NULL, we don't
 323  *      try to compress names. If 'lastdnptr' is NULL, we don't update the
 324  *      list.
 325  */
 326 int
 327 ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
 328              const u_char **dnptrs, const u_char **lastdnptr)
 329 {
 330         u_char *dstp;
 331         const u_char **cpp, **lpp, *eob, *msg;
 332         const u_char *srcp;
 333         int n, l;
 334
 335         srcp = src;
 336         dstp = dst;
 337         eob = dstp + dstsiz;
 338         lpp = cpp = NULL;
 339         if (dnptrs != NULL) {
 340                 if ((msg = *dnptrs++) != NULL) {
 341                         for (cpp = dnptrs; *cpp != NULL; cpp++)
 342                                 ;
 343                         lpp = cpp;      /* end of list to search */
 344                 }
 345         } else
 346                 msg = NULL;
 347
 348         /* make sure the domain we are about to add is legal */
 349         l = 0;
 350         do {
 351                 n = *srcp;
 352                 if ((n & NS_CMPRSFLGS) != 0) {
 353                         errno = EMSGSIZE;
 354                         return (-1);
 355                 }
 356                 l += n + 1;
 357                 if (l > MAXCDNAME) {
 358                         errno = EMSGSIZE;
 359                         return (-1);
 360                 }
 361                 srcp += n + 1;
 362         } while (n != 0);
 363
 364         srcp = src;
 365         do {
 366                 /* Look to see if we can use pointers. */
 367                 n = *srcp;
 368                 if (n != 0 && msg != NULL) {
 369                         l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
 370                                     (const u_char * const *)lpp);
 371                         if (l >= 0) {
 372                                 if (dstp + 1 >= eob) {
 373                                         errno = EMSGSIZE;
 374                                         return (-1);
 375                                 }
 376                                 *dstp++ = (l >> 8) | NS_CMPRSFLGS;
 377                                 *dstp++ = l % 256;
 378                                 return (dstp - dst);
 379                         }
 380                         /* Not found, save it. */
 381                         if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
 382                             (dstp - msg) < 0x4000) {
 383                                 *cpp++ = dstp;
 384                                 *cpp = NULL;
 385                         }
 386                 }
 387                 /* copy label to buffer */
 388                 if (n & NS_CMPRSFLGS) {         /* Should not happen. */
 389                         errno = EMSGSIZE;
 390                         return (-1);
 391                 }
 392                 if (dstp + 1 + n >= eob) {
 393                         errno = EMSGSIZE;
 394                         return (-1);
 395                 }
 396                 memcpy(dstp, srcp, n + 1);
 397                 srcp += n + 1;
 398                 dstp += n + 1;
 399         } while (n != 0);
 400
 401         if (dstp > eob) {
 402                 if (msg != NULL)
 403                         *lpp = NULL;
 404                 errno = EMSGSIZE;
 405                 return (-1);
 406         }
 407         return (dstp - dst);
 408 }
 409
 410 /*
 411  * ns_name_uncompress(msg, eom, src, dst, dstsiz)
 412  *      Expand compressed domain name to presentation format.
 413  * return:
 414  *      Number of bytes read out of `src', or -1 (with errno set).
 415  * note:
 416  *      Root domain returns as "." not "".
 417  */
 418 int
 419 ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
 420                    char *dst, size_t dstsiz)
 421 {
 422         u_char tmp[NS_MAXCDNAME];
 423         int n;
 424
 425         if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
 426                 return (-1);
 427         if (ns_name_ntop(tmp, dst, dstsiz) == -1)
 428                 return (-1);
 429         return (n);
 430 }
 431
 432 /*
 433  * ns_name_compress(src, dst, dstsiz, dnptrs, lastdnptr)
 434  *      Compress a domain name into wire format, using compression pointers.
 435  * return:
 436  *      Number of bytes consumed in `dst' or -1 (with errno set).
 437  * notes:
 438  *      'dnptrs' is an array of pointers to previous compressed names.
 439  *      dnptrs[0] is a pointer to the beginning of the message.
 440  *      The list ends with NULL.  'lastdnptr' is a pointer to the end of the
 441  *      array pointed to by 'dnptrs'. Side effect is to update the list of
 442  *      pointers for labels inserted into the message as we compress the name.
 443  *      If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
 444  *      is NULL, we don't update the list.
 445  */
 446 int
 447 ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
 448                  const u_char **dnptrs, const u_char **lastdnptr)
 449 {
 450         u_char tmp[NS_MAXCDNAME];
 451
 452         if (ns_name_pton(src, tmp, sizeof tmp) == -1)
 453                 return (-1);
 454         return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
 455 }
 456
 457 /*
 458  * ns_name_skip(ptrptr, eom)
 459  *      Advance *ptrptr to skip over the compressed name it points at.
 460  * return:
 461  *      0 on success, -1 (with errno set) on failure.
 462  */
 463 int
 464 ns_name_skip(const u_char **ptrptr, const u_char *eom) {
 465         const u_char *cp;
 466         u_int n;
 467
 468         cp = *ptrptr;
 469         while (cp < eom && (n = *cp++) != 0) {
 470                 /* Check for indirection. */
 471                 switch (n & NS_CMPRSFLGS) {
 472                 case 0:                 /* normal case, n == len */
 473                         cp += n;
 474                         continue;
 475                 case NS_CMPRSFLGS:      /* indirection */
 476                         cp++;
 477                         break;
 478                 default:                /* illegal type */
 479                         errno = EMSGSIZE;
 480                         return (-1);
 481                 }
 482                 break;
 483         }
 484         if (cp > eom) {
 485                 errno = EMSGSIZE;
 486                 return (-1);
 487         }
 488         *ptrptr = cp;
 489         return (0);
 490 }
 491
 492 /* Private. */
 493
 494 /*
 495  * special(ch)
 496  *      Thinking in noninternationalized USASCII (per the DNS spec),
 497  *      is this characted special ("in need of quoting") ?
 498  * return:
 499  *      boolean.
 500  */
 501 static int
 502 special(int ch) {
 503         switch (ch) {
 504         case 0x22: /* '"' */
 505         case 0x2E: /* '.' */
 506         case 0x3B: /* ';' */
 507         case 0x5C: /* '\\' */
 508         /* Special modifiers in zone files. */
 509         case 0x40: /* '@' */
 510         case 0x24: /* '$' */
 511                 return (1);
 512         default:
 513                 return (0);
 514         }
 515 }
 516
 517 /*
 518  * printable(ch)
 519  *      Thinking in noninternationalized USASCII (per the DNS spec),
 520  *      is this character visible and not a space when printed ?
 521  * return:
 522  *      boolean.
 523  */
 524 static int
 525 printable(int ch) {
 526         return (ch > 0x20 && ch < 0x7f);
 527 }
 528
 529 /*
 530  *      Thinking in noninternationalized USASCII (per the DNS spec),
 531  *      convert this character to lower case if it's upper case.
 532  */
 533 static int
 534 mklower(int ch) {
 535         if (ch >= 0x41 && ch <= 0x5A)
 536                 return (ch + 0x20);
 537         return (ch);
 538 }
 539
 540 /*
 541  * dn_find(domain, msg, dnptrs, lastdnptr)
 542  *      Search for the counted-label name in an array of compressed names.
 543  * return:
 544  *      offset from msg if found, or -1.
 545  * notes:
 546  *      dnptrs is the pointer to the first name on the list,
 547  *      not the pointer to the start of the message.
 548  */
 549 static int
 550 dn_find(const u_char *domain, const u_char *msg,
 551         const u_char * const *dnptrs,
 552         const u_char * const *lastdnptr)
 553 {
 554         const u_char *dn, *cp, *sp;
 555         const u_char * const *cpp;
 556         u_int n;
 557
 558         for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
 559                 dn = domain;
 560                 sp = cp = *cpp;
 561                 while ((n = *cp++) != 0) {
 562                         /*
 563                          * check for indirection
 564                          */
 565                         switch (n & NS_CMPRSFLGS) {
 566                         case 0:                 /* normal case, n == len */
 567                                 if (n != *dn++)
 568                                         goto next;
 569                                 for (; n > 0; n--)
 570                                         if (mklower(*dn++) != mklower(*cp++))
 571                                                 goto next;
 572                                 /* Is next root for both ? */
 573                                 if (*dn == '\0' && *cp == '\0')
 574                                         return (sp - msg);
 575                                 if (*dn)
 576                                         continue;
 577                                 goto next;
 578
 579                         case NS_CMPRSFLGS:      /* indirection */
 580                                 cp = msg + (((n & 0x3f) << 8) | *cp);
 581                                 break;
 582
 583                         default:        /* illegal type */
 584                                 errno = EMSGSIZE;
 585                                 return (-1);
 586                         }
 587                 }
 588  next: ;
 589         }
 590         errno = ENOENT;
 591         return (-1);
 592 }