diff options
Diffstat (limited to 'source4/heimdal/lib/krb5/get_host_realm.c')
| -rw-r--r-- | source4/heimdal/lib/krb5/get_host_realm.c | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/source4/heimdal/lib/krb5/get_host_realm.c b/source4/heimdal/lib/krb5/get_host_realm.c new file mode 100644 index 0000000000..e226598101 --- /dev/null +++ b/source4/heimdal/lib/krb5/get_host_realm.c @@ -0,0 +1,259 @@ +/* + * 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("$Id$"); + +/* 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; + unsigned 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; + } + } + p = strchr(host, '.'); + if(p != NULL) { + p++; + *realms = malloc(2 * sizeof(krb5_realm)); + if (*realms == NULL) { + krb5_set_error_message(context, ENOMEM, "malloc: out of memory"); + return ENOMEM; + } + + (*realms)[0] = strdup(p); + if((*realms)[0] == NULL) { + free(*realms); + krb5_set_error_message(context, ENOMEM, "malloc: out of memory"); + return ENOMEM; + } + strupr((*realms)[0]); + (*realms)[1] = NULL; + return 0; + } + krb5_set_error_message(context, KRB5_ERR_HOST_REALM_UNKNOWN, + "unable to find realm of host %s", host); + return KRB5_ERR_HOST_REALM_UNKNOWN; +} + +/* + * Return the realm(s) of `host' as a NULL-terminated list in + * `realms'. Free `realms' with krb5_free_host_realm(). + */ + +krb5_error_code KRB5_LIB_FUNCTION +krb5_get_host_realm(krb5_context context, + const char *targethost, + krb5_realm **realms) +{ + const char *host = targethost; + char hostname[MAXHOSTNAMELEN]; + krb5_error_code ret; + int use_dns; + + if (host == NULL) { + if (gethostname (hostname, sizeof(hostname))) { + *realms = NULL; + return errno; + } + host = hostname; + } + + /* + * If our local hostname is without components, don't even try to dns. + */ + + use_dns = (strchr(host, '.') != NULL); + + ret = _krb5_get_host_realm_int (context, host, use_dns, realms); + if (ret && targethost != NULL) { + /* + * If there was no realm mapping for the host (and we wasn't + * looking for ourself), guess at the local realm, maybe our + * KDC knows better then we do and we get a referral back. + */ + ret = krb5_get_default_realms(context, realms); + if (ret) { + krb5_set_error_message(context, KRB5_ERR_HOST_REALM_UNKNOWN, + "Unable to find realm of host %s", + host); + return KRB5_ERR_HOST_REALM_UNKNOWN; + } + } + return ret; +} |