heimdal/lib/krb5/krbhst.c

/*
 * Copyright (c) 1997 - 2001 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("$Id$");

/*
 * assuming that `*res' contains `*count' strings, add a copy of `string'.
 */

static int
add_string(krb5_context context, char ***res, int *count, const char *string)
{
    char **tmp = realloc(*res, (*count + 1) * sizeof(**res));

    if(tmp == NULL) {
	krb5_set_error_string (context, "malloc: out of memory");
	return ENOMEM;
    }
    *res = tmp;
    if(string) {
	tmp[*count] = strdup(string);
	if(tmp[*count] == NULL) {
	    krb5_set_error_string (context, "malloc: out of memory");
	    return ENOMEM;
	}
    } else
	tmp[*count] = NULL;
    (*count)++;
    return 0;
}

/*
 * do a SRV lookup for `realm, proto, service' returning the result
 * in `res, count'
 */

static krb5_error_code
srv_find_realm(krb5_context context, char ***res, int *count, 
	       const char *realm, const char *proto, const char *service)
{
    char domain[1024];
    char alt_domain[1024];
    krb5_error_code ret;
    struct dns_reply *r;
    struct resource_record *rr;

    snprintf(domain, sizeof(domain), "_%s._%s.%s.", service, proto, realm);
    
    r = dns_lookup(domain, "srv");
    if(r == NULL && context->srv_try_rfc2052) {
	snprintf(alt_domain, sizeof(alt_domain), "%s.%s.%s.", 
		 service, proto, realm);
	r = dns_lookup(alt_domain, "srv");
    }
    if(r == NULL && context->srv_try_txt)
	r = dns_lookup(domain, "txt");
    if(r == NULL && context->srv_try_rfc2052 && context->srv_try_txt)
	r = dns_lookup(alt_domain, "txt");
    if(r == NULL)
	return 0;

    for(rr = r->head; rr; rr = rr->next){
	if(rr->type == T_SRV){
	    char buf[1024];
	    char **tmp;

	    tmp = realloc(*res, (*count + 1) * sizeof(**res));
	    if (tmp == NULL) {
		krb5_set_error_string (context, "malloc: out of memory");
		return ENOMEM;
	    }
	    *res = tmp;
	    snprintf (buf, sizeof(buf),
		      "%s/%s:%u",
		      proto,
		      rr->u.srv->target,
		      rr->u.srv->port);
	    ret = add_string(context, res, count, buf);
	    if(ret)
		return ret;
	}else if(rr->type == T_TXT) {
	    ret = add_string(context, res, count, rr->u.txt);
	    if(ret)
		return ret;
	}
    }
    dns_free_data(r);
    return 0;
}

/*
 * lookup the servers for realm `realm', looking for the config string
 * `conf_string' in krb5.conf.
 * return a malloc-ed list of servers in hostlist or NULL if ther are none
 */

static void
get_krbhst_conf (krb5_context context,
		 const krb5_realm *realm,
		 const char *conf_string,
		 char ***hostlist)
{
    *hostlist = krb5_config_get_strings(context, NULL, 
					"realms", *realm, conf_string, NULL);
}

/*
 * lookup the servers for realm `realm', looking for the config string
 * `conf_string' in krb5.conf or for `serv_string' in SRV records.
 * return a malloc-ed list of servers in hostlist.
 */

static krb5_error_code
get_krbhst_dns (krb5_context context,
		const krb5_realm *realm,
		const char *serv_string,
		char ***hostlist,
		krb5_boolean fallback)
{
    char **res = *hostlist;
    int count = 0;
    krb5_error_code ret;

    if(context->srv_lookup) {
	char *s[] = { "udp", "tcp", "http" }, **q;
	for(q = s; q < s + sizeof(s) / sizeof(s[0]); q++) {
	    ret = srv_find_realm(context, &res, &count, *realm, *q,
				 serv_string);
	    if(ret) {
		krb5_config_free_strings(res);
		return ret;
	    }
	}
    }

    if(fallback && count == 0) {
	char buf[1024];
	snprintf(buf, sizeof(buf), "kerberos.%s", *realm);
	ret = add_string(context, &res, &count, buf);
	if(ret) {
	    krb5_config_free_strings(res);
	    return ret;
	}
	++count;
    }
    if (count)
	add_string(context, &res, &count, NULL);
    *hostlist = res;
    return 0;
}

/*
 * lookup the servers for realm `realm', looking for the config string
 * `conf_string' in krb5.conf or for `serv_string' in SRV records.
 * return a malloc-ed list of servers in hostlist.
 */

static krb5_error_code
get_krbhst (krb5_context context,
	    const krb5_realm *realm,
	    const char *conf_string,
	    const char *serv_string,
	    char ***hostlist,
	    krb5_boolean fallback)
{
    krb5_error_code ret = 0;

    get_krbhst_conf(context, realm, conf_string, hostlist);
    if (*hostlist == NULL)
	ret = get_krbhst_dns(context, realm, serv_string, hostlist, fallback);
    return ret;
}

/*
 * set `hostlist' to a malloced list of kadmin servers.
 */

krb5_error_code
krb5_get_krb_admin_hst (krb5_context context,
			const krb5_realm *realm,
			char ***hostlist)
{
    *hostlist = NULL;
    return get_krbhst (context, realm, "admin_server", "kerberos-adm",
		       hostlist, TRUE);
}

/*
 * set `hostlist' to a malloced list of changepw servers.
 */

krb5_error_code
krb5_get_krb_changepw_hst (krb5_context context,
			   const krb5_realm *realm,
			   char ***hostlist)
{
    krb5_error_code ret = 0;

    *hostlist = NULL;
    get_krbhst_conf (context, realm, "kpasswd_server",
		     hostlist);
    if (*hostlist == NULL)
	ret = get_krbhst (context, realm, "admin_server", "kpasswd",
			  hostlist, TRUE);
    return ret;
}

/*
 * set `hostlist' to a malloced list of 524 servers (per default the
 * KDCs)
 */

krb5_error_code
krb5_get_krb524hst (krb5_context context,
		    const krb5_realm *realm,
		    char ***hostlist)
{
    krb5_error_code ret = 0;

    *hostlist = NULL;
    get_krbhst_conf (context, realm, "krb524_server", hostlist);
    if (*hostlist == NULL) {
	ret = get_krbhst (context, realm, "krb524_server", "krb524", hostlist,
			  FALSE);
	if (ret)
	    return ret;
	if (*hostlist == NULL)
	    return krb5_get_krbhst(context, realm, hostlist);
    }
    return ret;
}

/*
 * set `hostlist' to a malloced list of kerberos servers.
 */

krb5_error_code
krb5_get_krbhst (krb5_context context,
		 const krb5_realm *realm,
		 char ***hostlist)
{
    *hostlist = NULL;
    return get_krbhst (context, realm, "kdc", "kerberos", hostlist, TRUE);
}

/*
 * free all memory associated with `hostlist'
 */

krb5_error_code
krb5_free_krbhst (krb5_context context,
		  char **hostlist)
{
    char **p;

    for (p = hostlist; *p; ++p)
	free (*p);
    free (hostlist);
    return 0;
}