dlls/dnsapi/ns_name.c

   1 /*
   2  * Copyright (c) 1996,1999 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 #include "config.h"
  19
  20 #ifdef HAVE_RESOLV
  21
  22 #include <sys/types.h>
  23
  24 #ifdef HAVE_NETINET_IN_H
  25 # include <netinet/in.h>
  26 #endif
  27 #ifdef HAVE_ARPA_NAMESER_H
  28 # include <arpa/nameser.h>
  29 #endif
  30
  31 #include <ctype.h>
  32 #include <errno.h>
  33 #ifdef HAVE_RESOLV_H
  34 # include <resolv.h>
  35 #endif
  36 #include <string.h>
  37
  38 /* Data. */
  39
  40 static const char       digits[] = "0123456789";
  41
  42 /* Forward. */
  43
  44 static int              special(int);
  45 static int              printable(int);
  46
  47 /* Public. */
  48
  49 /*
  50  * dns_ns_name_ntop(src, dst, dstsiz)
  51  *      Convert an encoded domain name to printable ascii as per RFC1035.
  52  * return:
  53  *      Number of bytes written to buffer, or -1 (with errno set)
  54  * notes:
  55  *      The root is returned as "."
  56  *      All other domains are returned in non absolute form
  57  */
  58 static int
  59 dns_ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) {
  60         const u_char *cp;
  61         char *dn, *eom;
  62         u_char c;
  63         u_int n;
  64
  65         cp = src;
  66         dn = dst;
  67         eom = dst + dstsiz;
  68
  69         while ((n = *cp++) != 0) {
  70                 if ((n & NS_CMPRSFLGS) != 0 && n != 0x41) {
  71                         /* Some kind of compression pointer. */
  72                         return (-1);
  73                 }
  74                 if (dn != dst) {
  75                         if (dn >= eom) {
  76                                 return (-1);
  77                         }
  78                         *dn++ = '.';
  79                 }
  80
  81                 if (n == 0x41) {
  82                         n = *cp++ / 8;
  83                         if (dn + n * 2 + 4 >= eom) {
  84                                 return (-1);
  85                         }
  86                         *dn++ = '\\';
  87                         *dn++ = '[';
  88                         *dn++ = 'x';
  89
  90                         while (n-- > 0) {
  91                 unsigned u;
  92                                 c = *cp++;
  93                                 u = c >> 4;
  94                                 *dn++ = u > 9 ? 'a' + u - 10 : '0' + u;
  95                                 u = c & 0xf;
  96                                 *dn++ = u > 9 ? 'a' + u - 10 : '0' + u;
  97                         }
  98
  99                         *dn++ = ']';
 100                         continue;
 101                 }
 102
 103                 if (dn + n >= eom) {
 104                         return (-1);
 105                 }
 106                 while (n-- > 0) {
 107                         c = *cp++;
 108                         if (special(c)) {
 109                                 if (dn + 1 >= eom) {
 110                                         return (-1);
 111                                 }
 112                                 *dn++ = '\\';
 113                                 *dn++ = (char)c;
 114                         } else if (!printable(c)) {
 115                                 if (dn + 3 >= eom) {
 116                                         return (-1);
 117                                 }
 118                                 *dn++ = '\\';
 119                                 *dn++ = digits[c / 100];
 120                                 *dn++ = digits[(c % 100) / 10];
 121                                 *dn++ = digits[c % 10];
 122                         } else {
 123                                 if (dn >= eom) {
 124                                         return (-1);
 125                                 }
 126                                 *dn++ = (char)c;
 127                         }
 128                 }
 129         }
 130         if (dn == dst) {
 131                 if (dn >= eom) {
 132                         return (-1);
 133                 }
 134                 *dn++ = '.';
 135         }
 136         if (dn >= eom) {
 137                 return (-1);
 138         }
 139         *dn++ = '\0';
 140         return (dn - dst);
 141 }
 142
 143 /*
 144  * dns_ns_name_pton(src, dst, dstsiz)
 145  *      Convert a ascii string into an encoded domain name as per RFC1035.
 146  * return:
 147  *      -1 if it fails
 148  *      1 if string was fully qualified
 149  *      0 is string was not fully qualified
 150  * notes:
 151  *      Enforces label and domain length limits.
 152  */
 153
 154 int
 155 dns_ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
 156         u_char *label, *bp, *eom;
 157         int c, n, escaped;
 158         char *cp;
 159
 160         escaped = 0;
 161         bp = dst;
 162         eom = dst + dstsiz;
 163         label = bp++;
 164
 165         while ((c = *src++) != 0) {
 166                 if (escaped) {
 167                         if ((cp = strchr(digits, c)) != NULL) {
 168                                 n = (cp - digits) * 100;
 169                                 if ((c = *src++) == 0 ||
 170                                     (cp = strchr(digits, c)) == NULL) {
 171                                         return (-1);
 172                                 }
 173                                 n += (cp - digits) * 10;
 174                                 if ((c = *src++) == 0 ||
 175                                     (cp = strchr(digits, c)) == NULL) {
 176                                         return (-1);
 177                                 }
 178                                 n += (cp - digits);
 179                                 if (n > 255) {
 180                                         return (-1);
 181                                 }
 182                                 c = n;
 183                         } else if (c == '[' && label == bp - 1 && *src == 'x') {
 184                                 /* Theoretically we would have to handle \[o
 185                                    as well but we do not since we do not need
 186                                    it internally.  */
 187                                 *label = 0x41;
 188                                 label = bp++;
 189                                 ++src;
 190                                 while (isxdigit (*src)) {
 191                                         n = *src > '9' ? *src - 'a' + 10 : *src - '0';
 192                                         ++src;
 193                                         if (! isxdigit(*src)) {
 194                                                 return (-1);
 195                                         }
 196                                         n <<= 4;
 197                                         n += *src > '9' ? *src - 'a' + 10 : *src - '0';
 198                                         if (bp + 1 >= eom) {
 199                                                 return (-1);
 200                                         }
 201                                         *bp++ = n;
 202                                         ++src;
 203                                 }
 204                                 *label = (bp - label - 1) * 8;
 205                                 if (*src++ != ']' || *src++ != '.') {
 206                                         return (-1);
 207                                 }
 208                                 escaped = 0;
 209                                 label = bp++;
 210                                 if (bp >= eom) {
 211                                         return (-1);
 212                                 }
 213                                 continue;
 214                         }
 215                         escaped = 0;
 216                 } else if (c == '\\') {
 217                         escaped = 1;
 218                         continue;
 219                 } else if (c == '.') {
 220                         c = (bp - label - 1);
 221                         if ((c & NS_CMPRSFLGS) != 0) {  /* Label too big. */
 222                                 return (-1);
 223                         }
 224                         if (label >= eom) {
 225                                 return (-1);
 226                         }
 227                         *label = c;
 228                         /* Fully qualified ? */
 229                         if (*src == '\0') {
 230                                 if (c != 0) {
 231                                         if (bp >= eom) {
 232                                                 return (-1);
 233                                         }
 234                                         *bp++ = '\0';
 235                                 }
 236                                 if ((bp - dst) > NS_MAXCDNAME) {
 237                                         return (-1);
 238                                 }
 239                                 return (1);
 240                         }
 241                         if (c == 0 || *src == '.') {
 242                                 return (-1);
 243                         }
 244                         label = bp++;
 245                         continue;
 246                 }
 247                 if (bp >= eom) {
 248                         return (-1);
 249                 }
 250                 *bp++ = (u_char)c;
 251         }
 252         c = (bp - label - 1);
 253         if ((c & NS_CMPRSFLGS) != 0) {          /* Label too big. */
 254                 return (-1);
 255         }
 256         if (label >= eom) {
 257                 return (-1);
 258         }
 259         *label = c;
 260         if (c != 0) {
 261                 if (bp >= eom) {
 262                         return (-1);
 263                 }
 264                 *bp++ = 0;
 265         }
 266         if ((bp - dst) > NS_MAXCDNAME) {        /* src too big */
 267                 return (-1);
 268         }
 269         return (0);
 270 }
 271
 272
 273 /*
 274  * dns_ns_name_unpack(msg, eom, src, dst, dstsiz)
 275  *      Unpack a domain name from a message, source may be compressed.
 276  * return:
 277  *      -1 if it fails, or consumed octets if it succeeds.
 278  */
 279 static int
 280 dns_ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
 281                u_char *dst, size_t dstsiz)
 282 {
 283         const u_char *srcp, *dstlim;
 284         u_char *dstp;
 285         int n, len, checked;
 286
 287         len = -1;
 288         checked = 0;
 289         dstp = dst;
 290         srcp = src;
 291         dstlim = dst + dstsiz;
 292         if (srcp < msg || srcp >= eom) {
 293                 return (-1);
 294         }
 295         /* Fetch next label in domain name. */
 296         while ((n = *srcp++) != 0) {
 297                 /* Check for indirection. */
 298                 switch (n & NS_CMPRSFLGS) {
 299                 case 0x40:
 300                         if (n == 0x41) {
 301                                 if (dstp + 1 >= dstlim) {
 302                                         return (-1);
 303                                 }
 304                                 *dstp++ = 0x41;
 305                                 n = *srcp++ / 8;
 306                                 ++checked;
 307                         } else {
 308                                 return (-1);            /* flag error */
 309                         }
 310                         /* FALLTHROUGH */
 311                 case 0:
 312                         /* Limit checks. */
 313                         if (dstp + n + 1 >= dstlim || srcp + n >= eom) {
 314                                 return (-1);
 315                         }
 316                         checked += n + 1;
 317                         dstp = memcpy(dstp, srcp - 1, n + 1);
 318                         dstp += n + 1;
 319                         srcp += n;
 320                         break;
 321
 322                 case NS_CMPRSFLGS:
 323                         if (srcp >= eom) {
 324                                 return (-1);
 325                         }
 326                         if (len < 0)
 327                                 len = srcp - src + 1;
 328                         srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
 329                         if (srcp < msg || srcp >= eom) {  /* Out of range. */
 330                                 return (-1);
 331                         }
 332                         checked += 2;
 333                         /*
 334                          * Check for loops in the compressed name;
 335                          * if we've looked at the whole message,
 336                          * there must be a loop.
 337                          */
 338                         if (checked >= eom - msg) {
 339                                 return (-1);
 340                         }
 341                         break;
 342
 343                 default:
 344                         return (-1);                    /* flag error */
 345                 }
 346         }
 347         *dstp = '\0';
 348         if (len < 0)
 349                 len = srcp - src;
 350         return (len);
 351 }
 352
 353
 354 /*
 355  * dns_ns_name_uncompress(msg, eom, src, dst, dstsiz)
 356  *      Expand compressed domain name to presentation format.
 357  * return:
 358  *      Number of bytes read out of `src', or -1 (with errno set).
 359  * note:
 360  *      Root domain returns as "." not "".
 361  */
 362 int
 363 dns_ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
 364                    char *dst, size_t dstsiz)
 365 {
 366         u_char tmp[NS_MAXCDNAME];
 367         int n;
 368
 369         if ((n = dns_ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
 370                 return (-1);
 371         if (dns_ns_name_ntop(tmp, dst, dstsiz) == -1)
 372                 return (-1);
 373         return (n);
 374 }
 375
 376
 377 /*
 378  * dns_ns_name_skip(ptrptr, eom)
 379  *      Advance *ptrptr to skip over the compressed name it points at.
 380  * return:
 381  *      0 on success, -1 (with errno set) on failure.
 382  */
 383 int
 384 dns_ns_name_skip(const u_char **ptrptr, const u_char *eom) {
 385         const u_char *cp;
 386         u_int n;
 387
 388         cp = *ptrptr;
 389         while (cp < eom && (n = *cp++) != 0) {
 390                 /* Check for indirection. */
 391                 switch (n & NS_CMPRSFLGS) {
 392                 case 0:                 /* normal case, n == len */
 393                         cp += n;
 394                         continue;
 395                 case NS_CMPRSFLGS:      /* indirection */
 396                         cp++;
 397                         break;
 398                 default:                /* illegal type */
 399                         return (-1);
 400                 }
 401                 break;
 402         }
 403         if (cp > eom) {
 404                 return (-1);
 405         }
 406         *ptrptr = cp;
 407         return (0);
 408 }
 409
 410 /* Private. */
 411
 412 /*
 413  * special(ch)
 414  *      Thinking in noninternationalized USASCII (per the DNS spec),
 415  *      is this character special ("in need of quoting") ?
 416  * return:
 417  *      boolean.
 418  */
 419 static int
 420 special(int ch) {
 421         switch (ch) {
 422         case 0x22: /* '"' */
 423         case 0x2E: /* '.' */
 424         case 0x3B: /* ';' */
 425         case 0x5C: /* '\\' */
 426         /* Special modifiers in zone files. */
 427         case 0x40: /* '@' */
 428         case 0x24: /* '$' */
 429                 return (1);
 430         default:
 431                 return (0);
 432         }
 433 }
 434
 435 /*
 436  * printable(ch)
 437  *      Thinking in noninternationalized USASCII (per the DNS spec),
 438  *      is this character visible and not a space when printed ?
 439  * return:
 440  *      boolean.
 441  */
 442 static int
 443 printable(int ch) {
 444         return (ch > 0x20 && ch < 0x7f);
 445 }
 446
 447 #endif  /* HAVE_RESOLV */