1  /* Skip over a (potentially compressed) domain name in wire format.
       2   * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
       3   * Copyright (c) 1996,1999 by Internet Software Consortium.
       4   *
       5   * Permission to use, copy, modify, and distribute this software for any
       6   * purpose with or without fee is hereby granted, provided that the above
       7   * copyright notice and this permission notice appear in all copies.
       8   *
       9   * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
      10   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
      11   * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
      12   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
      13   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
      14   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
      15   * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
      16   */
      17  
      18  #include <arpa/nameser.h>
      19  #include <errno.h>
      20  #include <shlib-compat.h>
      21  
      22  /* Advances *PTRPTR to skip over the compressed name it points at.
      23     Returns 0 on success, -1 (with errno set) on failure.  */
      24  int
      25  ___ns_name_skip (const unsigned char **ptrptr, const unsigned char *eom)
      26  {
      27    const unsigned char *cp;
      28    unsigned int n;
      29  
      30    cp = *ptrptr;
      31    while (cp < eom)
      32      {
      33        n = *cp++;
      34        if (n == 0)
      35          {
      36            /* End of domain name without indirection.  */
      37            *ptrptr = cp;
      38            return 0;
      39          }
      40  
      41        /* Check for indirection.  */
      42        switch (n & NS_CMPRSFLGS)
      43          {
      44          case 0:                 /* Normal case, n == len.  */
      45            if (eom - cp < n)
      46              goto malformed;
      47            cp += n;
      48            break;
      49          case NS_CMPRSFLGS:      /* Indirection.  */
      50            if (cp == eom)
      51              /* No room for second indirection byte.  */
      52              goto malformed;
      53            *ptrptr = cp + 1;
      54            return 0;
      55          default:                /* Illegal type.  */
      56            goto malformed;
      57          }
      58      }
      59  
      60   malformed:
      61    __set_errno (EMSGSIZE);
      62    return -1;
      63  }
      64  versioned_symbol (libc, ___ns_name_skip, ns_name_skip, GLIBC_2_34);
      65  versioned_symbol (libc, ___ns_name_skip, __ns_name_skip, GLIBC_PRIVATE);
      66  libc_hidden_ver (___ns_name_skip, __ns_name_skip)
      67  
      68  #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_9, GLIBC_2_34)
      69  compat_symbol (libresolv, ___ns_name_skip, ns_name_skip, GLIBC_2_9);
      70  #endif