resolv/ns_makecanon.c

   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)