2 * Copyright (c) 1997 - 2005 Kungliga Tekniska Högskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
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34 #include "krb5_locl.h"
37 /* To automagically find the correct realm of a host (without
38 * [domain_realm] in krb5.conf) add a text record for your domain with
39 * the name of your realm, like this:
41 * _kerberos IN TXT "FOO.SE"
43 * The search is recursive, so you can add entries for specific
44 * hosts. To find the realm of host a.b.c, it first tries
45 * _kerberos.a.b.c, then _kerberos.b.c and so on.
47 * This method is described in draft-ietf-cat-krb-dns-locate-03.txt.
52 copy_txt_to_realms (struct rk_resource_record *head,
55 struct rk_resource_record *rr;
58 for(n = 0, rr = head; rr; rr = rr->next)
59 if (rr->type == rk_ns_t_txt)
65 *realms = malloc ((n + 1) * sizeof(krb5_realm));
69 for (i = 0; i < n + 1; ++i)
72 for (i = 0, rr = head; rr; rr = rr->next) {
73 if (rr->type == rk_ns_t_txt) {
76 tmp = strdup(rr->u.txt);
78 for (i = 0; i < n; ++i)
91 dns_find_realm(krb5_context context,
95 static const char *default_labels[] = { "_kerberos", NULL };
96 char dom[MAXHOSTNAMELEN];
97 struct rk_dns_reply *r;
102 config_labels = krb5_config_get_strings(context, NULL, "libdefaults",
103 "dns_lookup_realm_labels", NULL);
104 if(config_labels != NULL)
105 labels = (const char **)config_labels;
107 labels = default_labels;
110 for (i = 0; labels[i] != NULL; i++) {
111 ret = snprintf(dom, sizeof(dom), "%s.%s.", labels[i], domain);
112 if(ret < 0 || (size_t)ret >= sizeof(dom)) {
114 krb5_config_free_strings(config_labels);
117 r = rk_dns_lookup(dom, "TXT");
119 ret = copy_txt_to_realms (r->head, realms);
123 krb5_config_free_strings(config_labels);
129 krb5_config_free_strings(config_labels);
134 * Try to figure out what realms host in `domain' belong to from the
135 * configuration file.
139 config_find_realm(krb5_context context,
143 char **tmp = krb5_config_get_strings (context, NULL,
155 * This function assumes that `host' is a FQDN (and doesn't handle the
156 * special case of host == NULL either).
157 * Try to find mapping in the config file or DNS and it that fails,
158 * fall back to guessing
161 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
162 _krb5_get_host_realm_int (krb5_context context,
164 krb5_boolean use_dns,
168 krb5_boolean dns_locate_enable;
170 dns_locate_enable = krb5_config_get_bool_default(context, NULL, TRUE,
171 "libdefaults", "dns_lookup_realm", NULL);
172 for (p = host; p != NULL; p = strchr (p + 1, '.')) {
173 if(config_find_realm(context, p, realms) == 0) {
174 if(strcasecmp(*realms[0], "dns_locate") == 0) {
176 for (q = host; q != NULL; q = strchr(q + 1, '.'))
177 if(dns_find_realm(context, q, realms) == 0)
183 else if(use_dns && dns_locate_enable) {
184 if(dns_find_realm(context, p, realms) == 0)
188 p = strchr(host, '.');
191 *realms = malloc(2 * sizeof(krb5_realm));
192 if (*realms == NULL) {
193 krb5_set_error_message(context, ENOMEM, N_("malloc: out of memory", ""));
197 (*realms)[0] = strdup(p);
198 if((*realms)[0] == NULL) {
200 krb5_set_error_message(context, ENOMEM, N_("malloc: out of memory", ""));
203 strupr((*realms)[0]);
207 krb5_set_error_message(context, KRB5_ERR_HOST_REALM_UNKNOWN,
208 N_("unable to find realm of host %s", ""),
210 return KRB5_ERR_HOST_REALM_UNKNOWN;
214 * Return the realm(s) of `host' as a NULL-terminated list in
215 * `realms'. Free `realms' with krb5_free_host_realm().
218 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
219 krb5_get_host_realm(krb5_context context,
220 const char *targethost,
223 const char *host = targethost;
224 char hostname[MAXHOSTNAMELEN];
229 if (gethostname (hostname, sizeof(hostname))) {
237 * If our local hostname is without components, don't even try to dns.
240 use_dns = (strchr(host, '.') != NULL);
242 ret = _krb5_get_host_realm_int (context, host, use_dns, realms);
243 if (ret && targethost != NULL) {
245 * If there was no realm mapping for the host (and we wasn't
246 * looking for ourself), guess at the local realm, maybe our
247 * KDC knows better then we do and we get a referral back.
249 ret = krb5_get_default_realms(context, realms);
251 krb5_set_error_message(context, KRB5_ERR_HOST_REALM_UNKNOWN,
252 N_("Unable to find realm of host %s", ""),
254 return KRB5_ERR_HOST_REALM_UNKNOWN;