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