lib/krb5/expand_hostname.c

   1 /*
   2  * Copyright (c) 1999 - 2001 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "krb5_locl.h"
  35
  36 static krb5_error_code
  37 copy_hostname(krb5_context context,
  38               const char *orig_hostname,
  39               char **new_hostname)
  40 {
  41     *new_hostname = strdup (orig_hostname);
  42     if (*new_hostname == NULL)
  43         return krb5_enomem(context);
  44     strlwr (*new_hostname);
  45     return 0;
  46 }
  47
  48 /**
  49  * krb5_expand_hostname() tries to make orig_hostname into a more
  50  * canonical one in the newly allocated space returned in
  51  * new_hostname.
  52
  53  * @param context a Keberos context
  54  * @param orig_hostname hostname to canonicalise.
  55  * @param new_hostname output hostname, caller must free hostname with
  56  *        krb5_xfree().
  57  *
  58  * @return Return an error code or 0, see krb5_get_error_message().
  59  *
  60  * @ingroup krb5_support
  61  */
  62
  63 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
  64 krb5_expand_hostname (krb5_context context,
  65                       const char *orig_hostname,
  66                       char **new_hostname)
  67 {
  68     struct addrinfo *ai, *a, hints;
  69     int error;
  70
  71     if ((context->flags & KRB5_CTX_F_DNS_CANONICALIZE_HOSTNAME) == 0)
  72         return copy_hostname (context, orig_hostname, new_hostname);
  73
  74     memset (&hints, 0, sizeof(hints));
  75     hints.ai_flags = AI_CANONNAME;
  76
  77     error = getaddrinfo (orig_hostname, NULL, &hints, &ai);
  78     if (error)
  79         return copy_hostname (context, orig_hostname, new_hostname);
  80     for (a = ai; a != NULL; a = a->ai_next) {
  81         if (a->ai_canonname != NULL) {
  82             *new_hostname = strdup (a->ai_canonname);
  83             freeaddrinfo (ai);
  84             if (*new_hostname == NULL)
  85                 return krb5_enomem(context);
  86             else
  87                 return 0;
  88         }
  89     }
  90     freeaddrinfo (ai);
  91     return copy_hostname (context, orig_hostname, new_hostname);
  92 }
  93
  94 /*
  95  * handle the case of the hostname being unresolvable and thus identical
  96  */
  97
  98 static krb5_error_code
  99 vanilla_hostname (krb5_context context,
 100                   const char *orig_hostname,
 101                   char **new_hostname,
 102                   char ***realms)
 103 {
 104     krb5_error_code ret;
 105
 106     ret = copy_hostname (context, orig_hostname, new_hostname);
 107     if (ret)
 108         return ret;
 109     strlwr (*new_hostname);
 110
 111     ret = krb5_get_host_realm (context, *new_hostname, realms);
 112     if (ret) {
 113         free (*new_hostname);
 114         return ret;
 115     }
 116     return 0;
 117 }
 118
 119 /**
 120  * krb5_expand_hostname_realms() expands orig_hostname to a name we
 121  * believe to be a hostname in newly allocated space in new_hostname
 122  * and return the realms new_hostname is believed to belong to in
 123  * realms.
 124  *
 125  * @param context a Keberos context
 126  * @param orig_hostname hostname to canonicalise.
 127  * @param new_hostname output hostname, caller must free hostname with
 128  *        krb5_xfree().
 129  * @param realms output possible realms, is an array that is terminated
 130  *        with NULL. Caller must free with krb5_free_host_realm().
 131  *
 132  * @return Return an error code or 0, see krb5_get_error_message().
 133  *
 134  * @ingroup krb5_support
 135  */
 136
 137 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 138 krb5_expand_hostname_realms (krb5_context context,
 139                              const char *orig_hostname,
 140                              char **new_hostname,
 141                              char ***realms)
 142 {
 143     struct addrinfo *ai, *a, hints;
 144     int error;
 145     krb5_error_code ret = 0;
 146
 147     if ((context->flags & KRB5_CTX_F_DNS_CANONICALIZE_HOSTNAME) == 0)
 148         return vanilla_hostname (context, orig_hostname, new_hostname,
 149                                  realms);
 150
 151     memset (&hints, 0, sizeof(hints));
 152     hints.ai_flags = AI_CANONNAME;
 153
 154     error = getaddrinfo (orig_hostname, NULL, &hints, &ai);
 155     if (error)
 156         return vanilla_hostname (context, orig_hostname, new_hostname,
 157                                  realms);
 158
 159     for (a = ai; a != NULL; a = a->ai_next) {
 160         if (a->ai_canonname != NULL) {
 161             ret = copy_hostname (context, a->ai_canonname, new_hostname);
 162             if (ret) {
 163                 freeaddrinfo (ai);
 164                 return ret;
 165             }
 166             strlwr (*new_hostname);
 167             ret = krb5_get_host_realm (context, *new_hostname, realms);
 168             if (ret == 0) {
 169                 freeaddrinfo (ai);
 170                 return 0;
 171             }
 172             free (*new_hostname);
 173         }
 174     }
 175     freeaddrinfo(ai);
 176     return vanilla_hostname (context, orig_hostname, new_hostname, realms);
 177 }