resolv/ns_name.c

   1 /*
   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 <sys/types.h>
  19
  20 #include <netinet/in.h>
  21 #include <arpa/nameser.h>
  22
  23 #include <errno.h>
  24 #include <resolv.h>
  25 #include <string.h>
  26 #include <ctype.h>
  27 #include <stdlib.h>
  28 #include <limits.h>
  29
  30 # define SPRINTF(x) ((size_t)sprintf x)
  31
  32 /* Forward. */
  33
  34 static int              labellen(const u_char *);
  35
  36 /* Public. */
  37
  38 /*%
  39  *      Convert a network strings labels into all lowercase.
  40  *
  41  * return:
  42  *\li   Number of bytes written to buffer, or -1 (with errno set)
  43  *
  44  * notes:
  45  *\li   Enforces label and domain length limits.
  46  */
  47
  48 int
  49 ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz)
  50 {
  51         const u_char *cp;
  52         u_char *dn, *eom;
  53         u_char c;
  54         u_int n;
  55         int l;
  56
  57         cp = src;
  58         dn = dst;
  59         eom = dst + dstsiz;
  60
  61         if (dn >= eom) {
  62                 __set_errno (EMSGSIZE);
  63                 return (-1);
  64         }
  65         while ((n = *cp++) != 0) {
  66                 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
  67                         /* Some kind of compression pointer. */
  68                         __set_errno (EMSGSIZE);
  69                         return (-1);
  70                 }
  71                 *dn++ = n;
  72                 if ((l = labellen(cp - 1)) < 0) {
  73                         __set_errno (EMSGSIZE);
  74                         return (-1);
  75                 }
  76                 if (dn + l >= eom) {
  77                         __set_errno (EMSGSIZE);
  78                         return (-1);
  79                 }
  80                 for ((void)NULL; l > 0; l--) {
  81                         c = *cp++;
  82                         if (isupper(c))
  83                                 *dn++ = tolower(c);
  84                         else
  85                                 *dn++ = c;
  86                 }
  87         }
  88         *dn++ = '\0';
  89         return (dn - dst);
  90 }
  91
  92 /*%
  93  * Reset dnptrs so that there are no active references to pointers at or
  94  * after src.
  95  */
  96 void
  97 ns_name_rollback(const u_char *src, const u_char **dnptrs,
  98                  const u_char **lastdnptr)
  99 {
 100         while (dnptrs < lastdnptr && *dnptrs != NULL) {
 101                 if (*dnptrs >= src) {
 102                         *dnptrs = NULL;
 103                         break;
 104                 }
 105                 dnptrs++;
 106         }
 107 }
 108
 109 /* Private. */
 110
 111 /* Return the length of the encoded label starting at LP, or -1 for
 112    compression references and extended label types.  */
 113 static int
 114 labellen (const unsigned char *lp)
 115 {
 116   if (*lp <= 63)
 117     return *lp;
 118   return -1;
 119 }
 120
 121 /*! \file */