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/*
* Copyright (c) 1997 - 2005 Kungliga Tekniska Högskolan
* (Royal Institute of Technology, Stockholm, Sweden).
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "krb5_locl.h"
#include <resolve.h>
RCSID("$Id: get_host_realm.c,v 1.35 2005/08/23 08:14:02 lha Exp $");
/* To automagically find the correct realm of a host (without
* [domain_realm] in krb5.conf) add a text record for your domain with
* the name of your realm, like this:
*
* _kerberos IN TXT "FOO.SE"
*
* The search is recursive, so you can add entries for specific
* hosts. To find the realm of host a.b.c, it first tries
* _kerberos.a.b.c, then _kerberos.b.c and so on.
*
* This method is described in draft-ietf-cat-krb-dns-locate-03.txt.
*
*/
static int
copy_txt_to_realms (struct resource_record *head,
krb5_realm **realms)
{
struct resource_record *rr;
int n, i;
for(n = 0, rr = head; rr; rr = rr->next)
if (rr->type == T_TXT)
++n;
if (n == 0)
return -1;
*realms = malloc ((n + 1) * sizeof(krb5_realm));
if (*realms == NULL)
return -1;
for (i = 0; i < n + 1; ++i)
(*realms)[i] = NULL;
for (i = 0, rr = head; rr; rr = rr->next) {
if (rr->type == T_TXT) {
char *tmp;
tmp = strdup(rr->u.txt);
if (tmp == NULL) {
for (i = 0; i < n; ++i)
free ((*realms)[i]);
free (*realms);
return -1;
}
(*realms)[i] = tmp;
++i;
}
}
return 0;
}
static int
dns_find_realm(krb5_context context,
const char *domain,
krb5_realm **realms)
{
static const char *default_labels[] = { "_kerberos", NULL };
char dom[MAXHOSTNAMELEN];
struct dns_reply *r;
const char **labels;
char **config_labels;
int i, ret;
config_labels = krb5_config_get_strings(context, NULL, "libdefaults",
"dns_lookup_realm_labels", NULL);
if(config_labels != NULL)
labels = (const char **)config_labels;
else
labels = default_labels;
if(*domain == '.')
domain++;
for (i = 0; labels[i] != NULL; i++) {
ret = snprintf(dom, sizeof(dom), "%s.%s.", labels[i], domain);
if(ret < 0 || ret >= sizeof(dom)) {
if (config_labels)
krb5_config_free_strings(config_labels);
return -1;
}
r = dns_lookup(dom, "TXT");
if(r != NULL) {
ret = copy_txt_to_realms (r->head, realms);
dns_free_data(r);
if(ret == 0) {
if (config_labels)
krb5_config_free_strings(config_labels);
return 0;
}
}
}
if (config_labels)
krb5_config_free_strings(config_labels);
return -1;
}
/*
* Try to figure out what realms host in `domain' belong to from the
* configuration file.
*/
static int
config_find_realm(krb5_context context,
const char *domain,
krb5_realm **realms)
{
char **tmp = krb5_config_get_strings (context, NULL,
"domain_realm",
domain,
NULL);
if (tmp == NULL)
return -1;
*realms = tmp;
return 0;
}
/*
* This function assumes that `host' is a FQDN (and doesn't handle the
* special case of host == NULL either).
* Try to find mapping in the config file or DNS and it that fails,
* fall back to guessing
*/
krb5_error_code KRB5_LIB_FUNCTION
_krb5_get_host_realm_int (krb5_context context,
const char *host,
krb5_boolean use_dns,
krb5_realm **realms)
{
const char *p, *q;
krb5_boolean dns_locate_enable;
dns_locate_enable = krb5_config_get_bool_default(context, NULL, TRUE,
"libdefaults", "dns_lookup_realm", NULL);
for (p = host; p != NULL; p = strchr (p + 1, '.')) {
if(config_find_realm(context, p, realms) == 0) {
if(strcasecmp(*realms[0], "dns_locate") == 0) {
if(use_dns)
for (q = host; q != NULL; q = strchr(q + 1, '.'))
if(dns_find_realm(context, q, realms) == 0)
return 0;
continue;
} else
return 0;
}
else if(use_dns && dns_locate_enable) {
if(dns_find_realm(context, p, realms) == 0)
return 0;
}
}
*realms = malloc(2 * sizeof(krb5_realm));
if (*realms == NULL) {
krb5_set_error_string(context, "malloc: out of memory");
return ENOMEM;
}
(*realms)[1] = NULL;
p = strchr(host, '.');
if(p != NULL) {
p++;
(*realms)[0] = strdup(p);
if((*realms)[0] == NULL) {
free(*realms);
krb5_set_error_string(context, "malloc: out of memory");
return ENOMEM;
}
strupr((*realms)[0]);
} else {
krb5_error_code ret;
ret = krb5_get_default_realm(context, &(*realms)[0]);
if(ret) {
free(*realms);
krb5_set_error_string(context, "malloc: out of memory");
return ENOMEM;
}
if((*realms)[0] == NULL) {
free(*realms);
krb5_set_error_string(context, "unable to find realm of host %s", host);
return KRB5_ERR_HOST_REALM_UNKNOWN;
}
}
return 0;
}
/*
* Return the realm(s) of `host' as a NULL-terminated list in `realms'.
*/
krb5_error_code KRB5_LIB_FUNCTION
krb5_get_host_realm(krb5_context context,
const char *host,
krb5_realm **realms)
{
char hostname[MAXHOSTNAMELEN];
krb5_boolean use_dns;
if (host == NULL) {
if (gethostname (hostname, sizeof(hostname)))
return errno;
host = hostname;
}
if (strchr(host, '.') == NULL) {
use_dns = FALSE;
} else {
use_dns = TRUE;
}
return _krb5_get_host_realm_int (context, host, use_dns, realms);
}
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