1 /* 2 * Copyright (c) 1997, 1998, 1999 Kungliga Tekniska H�gskolan 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 #include <resolve.h> 36 37 RCSID("$Id: get_host_realm.c,v 1.25 1999/12/11 23:14:07 assar Exp $"); 38 39 /* To automagically find the correct realm of a host (without 40 * [domain_realm] in krb5.conf) add a text record for your domain with 41 * the name of your realm, like this: 42 * 43 * krb5-realm IN TXT FOO.SE 44 * 45 * The search is recursive, so you can add entries for specific 46 * hosts. To find the realm of host a.b.c, it first tries 47 * krb5-realm.a.b.c, then krb5-realm.b.c and so on. 48 * 49 * Also supported is _kerberos (following draft-ietf-cat-krb-dns-locate-01.txt) 50 * 51 */ 52 53 static int 54 copy_txt_to_realms (struct resource_record *head, 55 krb5_realm **realms) 56 { 57 struct resource_record *rr; 58 int n, i; 59 60 for(n = 0, rr = head; rr; rr = rr->next) 61 if (rr->type == T_TXT) 62 ++n; 63 64 if (n == 0) 65 return -1; 66 67 *realms = malloc ((n + 1) * sizeof(krb5_realm)); 68 if (*realms == NULL) 69 return -1; 70 71 for (i = 0; i < n + 1; ++i) 72 (*realms)[i] = NULL; 73 74 for (i = 0, rr = head; rr; rr = rr->next) { 75 if (rr->type == T_TXT) { 76 char *tmp; 77 78 tmp = strdup(rr->u.txt); 79 if (tmp == NULL) { 80 for (i = 0; i < n; ++i) 81 free ((*realms)[i]); 82 free (*realms); 83 return -1; 84 } 85 (*realms)[i] = tmp; 86 ++i; 87 } 88 } 89 return 0; 90 } 91 92 static int 93 dns_find_realm(krb5_context context, 94 const char *domain, 95 const char *dom_string, 96 krb5_realm **realms) 97 { 98 char dom[MAXHOSTNAMELEN]; 99 struct dns_reply *r; 100 int ret; 101 102 if(*domain == '.') 103 domain++; 104 snprintf(dom, sizeof(dom), "%s.%s.", dom_string, domain); 105 r = dns_lookup(dom, "TXT"); 106 if(r == NULL) 107 return -1; 108 109 ret = copy_txt_to_realms (r->head, realms); 110 dns_free_data(r); 111 return ret; 112 } 113 114 /* 115 * Try to figure out what realms host in `domain' belong to from the 116 * configuration file. 117 */ 118 119 static int 120 config_find_realm(krb5_context context, 121 const char *domain, 122 krb5_realm **realms) 123 { 124 char **tmp = krb5_config_get_strings (context, NULL, 125 "domain_realm", 126 domain, 127 NULL); 128 129 if (tmp == NULL) 130 return -1; 131 *realms = tmp; 132 return 0; 133 } 134 135 /* 136 * This function assumes that `host' is a FQDN (and doesn't handle the 137 * special case of host == NULL either). 138 * Try to find mapping in the config file or DNS and it that fails, 139 * fall back to guessing 140 */ 141 142 krb5_error_code 143 krb5_get_host_realm_int (krb5_context context, 144 const char *host, 145 krb5_realm **realms) 146 { 147 const char *p; 148 149 for (p = host; p != NULL; p = strchr (p + 1, '.')) { 150 if(config_find_realm(context, p, realms) == 0) 151 return 0; 152 else if(dns_find_realm(context, p, "krb5-realm", realms) == 0) 153 return 0; 154 else if(dns_find_realm(context, p, "_kerberos", realms) == 0) 155 return 0; 156 } 157 p = strchr(host, '.'); 158 if(p != NULL) { 159 p++; 160 *realms = malloc(2 * sizeof(krb5_realm)); 161 if (*realms == NULL) 162 return ENOMEM; 163 164 (*realms)[0] = strdup(p); 165 if((*realms)[0] == NULL) { 166 free(*realms); 167 return ENOMEM; 168 } 169 strupr((*realms)[0]); 170 (*realms)[1] = NULL; 171 return 0; 172 } 173 return KRB5_ERR_HOST_REALM_UNKNOWN; 174 } 175 176 /* 177 * Return the realm(s) of `host' as a NULL-terminated list in `realms'. 178 */ 179 180 krb5_error_code 181 krb5_get_host_realm(krb5_context context, 182 const char *host, 183 krb5_realm **realms) 184 { 185 char hostname[MAXHOSTNAMELEN]; 186 187 if (host == NULL) { 188 if (gethostname (hostname, sizeof(hostname))) 189 return errno; 190 host = hostname; 191 } 192 193 return krb5_get_host_realm_int (context, host, realms); 194 } 195