1  /* Add missing "." to domain names.
       2   * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
       3   * Copyright (c) 1995,1999 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
      10   * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
      11   * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
      12   * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
      13   * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
      14   * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
      15   * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
      16   * SOFTWARE.
      17   */
      18  
      19  #include <arpa/nameser.h>
      20  #include <errno.h>
      21  #include <string.h>
      22  
      23  /* Make a canonical copy of domain name SRC in DST.  Behavior:
      24        foo -> foo.
      25        foo. -> foo.
      26        foo.. -> foo.
      27        foo\. -> foo\..
      28        foo\\. -> foo\\.  */
      29  int
      30  __libc_ns_makecanon (const char *src, char *dst, size_t dstsize)
      31  {
      32    size_t n = strlen (src);
      33  
      34    if (n + sizeof "." > dstsize) /* sizeof == 2.  */
      35      {
      36        __set_errno (EMSGSIZE);
      37        return -1;
      38      }
      39    strcpy (dst, src);
      40    while (n >= 1U && dst[n - 1] == '.')   /* Ends in ".".  */
      41      if (n >= 2U && dst[n - 2] == '\\' && /* Ends in "\.".  */
      42          (n < 3U || dst[n - 3] != '\\'))  /* But not "\\.".  */
      43        break;
      44      else
      45        dst[--n] = '\0';
      46    dst[n++] = '.';
      47    dst[n] = '\0';
      48    return 0;
      49  }
      50  libc_hidden_def (__libc_ns_makecanon)