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/*
Unix SMB/CIFS implementation.
Winbind daemon connection manager
Copyright (C) Tim Potter 2001
Copyright (C) Andrew Bartlett 2002
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
#define FAILED_CONNECTION_CACHE_TIMEOUT 30 /* Seconds between attempts */
struct failed_connection_cache {
fstring domain_name;
fstring controller;
time_t lookup_time;
NTSTATUS nt_status;
struct failed_connection_cache *prev, *next;
};
static struct failed_connection_cache *failed_connection_cache;
/**********************************************************************
Check for a previously failed connection
**********************************************************************/
static NTSTATUS check_negative_conn_cache( const char *domain, const char *server )
{
struct failed_connection_cache *fcc;
NTSTATUS result = NT_STATUS_UNSUCCESSFUL;
/* can't check if we don't have strings */
if ( !domain || !server )
return NT_STATUS_OK;
for (fcc = failed_connection_cache; fcc; fcc = fcc->next) {
/*
* we have a match IFF the domain and server name matches
* (a) the domain matches,
* (b) the IP address matches (if we have one)
* (c) the server name (if specified) matches
*/
if ( !strequal(domain, fcc->domain_name) || !strequal(server, fcc->controller) )
continue; /* no match; check the next entry */
/* we have a match so see if it is still current */
if ((time(NULL) - fcc->lookup_time) > FAILED_CONNECTION_CACHE_TIMEOUT)
{
/* Cache entry has expired, delete it */
DEBUG(10, ("check_negative_conn_cache: cache entry expired for %s, %s\n",
domain, server ));
DLIST_REMOVE(failed_connection_cache, fcc);
SAFE_FREE(fcc);
return NT_STATUS_OK;
}
/* The timeout hasn't expired yet so return false */
DEBUG(10, ("check_negative_conn_cache: returning negative entry for %s, %s\n",
domain, server ));
result = fcc->nt_status;
return result;
}
/* end of function means no cache entry */
return NT_STATUS_OK;
}
/**********************************************************************
Add an entry to the failed conneciton cache
**********************************************************************/
void add_failed_connection_entry(const char *domain, const char *server, NTSTATUS result)
{
struct failed_connection_cache *fcc;
SMB_ASSERT(!NT_STATUS_IS_OK(result));
/* Check we already aren't in the cache. We always have to have
a domain, but maybe not a specific DC name. */
for (fcc = failed_connection_cache; fcc; fcc = fcc->next) {
if ( strequal(fcc->domain_name, domain) && strequal(fcc->controller, server) )
{
DEBUG(10, ("add_failed_connection_entry: domain %s (%s) already tried and failed\n",
domain, server ));
return;
}
}
/* Create negative lookup cache entry for this domain and controller */
if ( !(fcc = (struct failed_connection_cache *)malloc(sizeof(struct failed_connection_cache))) )
{
DEBUG(0, ("malloc failed in add_failed_connection_entry!\n"));
return;
}
ZERO_STRUCTP(fcc);
fstrcpy( fcc->domain_name, domain );
fstrcpy( fcc->controller, server );
fcc->lookup_time = time(NULL);
fcc->nt_status = result;
DEBUG(10,("add_failed_connection_entry: added domain %s (%s) to failed conn cache\n",
domain, server ));
DLIST_ADD(failed_connection_cache, fcc);
}
/****************************************************************************
****************************************************************************/
void flush_negative_conn_cache( void )
{
struct failed_connection_cache *fcc;
fcc = failed_connection_cache;
while (fcc) {
struct failed_connection_cache *fcc_next;
fcc_next = fcc->next;
DLIST_REMOVE(failed_connection_cache, fcc);
free(fcc);
fcc = fcc_next;
}
}
/****************************************************************************
Utility function to return the name of a DC using RPC. The name is
guaranteed to be valid since we have already done a name_status_find on it
and we have checked our negative connection cache
***************************************************************************/
BOOL rpc_find_dc(const char *domain, fstring srv_name, struct in_addr *ip_out)
{
struct in_addr *ip_list = NULL, dc_ip, exclude_ip;
int count, i;
BOOL list_ordered;
BOOL use_pdc_only;
NTSTATUS result;
zero_ip(&exclude_ip);
use_pdc_only = must_use_pdc(domain);
/* Lookup domain controller name */
if ( use_pdc_only && get_pdc_ip(domain, &dc_ip) )
{
DEBUG(10,("rpc_find_dc: Atempting to lookup PDC to avoid sam sync delays\n"));
if (name_status_find(domain, 0x1c, 0x20, dc_ip, srv_name)) {
/* makre we we haven't tried this on previously and failed */
result = check_negative_conn_cache( domain, srv_name );
if ( NT_STATUS_IS_OK(result) )
goto done;
}
/* Didn't get name, remember not to talk to this DC. */
exclude_ip = dc_ip;
}
/* get a list of all domain controllers */
if (!get_dc_list( domain, &ip_list, &count, &list_ordered) ) {
DEBUG(3, ("Could not look up dc's for domain %s\n", domain));
return False;
}
/* Remove the entry we've already failed with (should be the PDC). */
if ( use_pdc_only ) {
for (i = 0; i < count; i++) {
if (ip_equal( exclude_ip, ip_list[i]))
zero_ip(&ip_list[i]);
}
}
/* Pick a nice close server, but only if the list was not ordered */
if (!list_ordered && (count > 1) ) {
qsort(ip_list, count, sizeof(struct in_addr), QSORT_CAST ip_compare);
}
for (i = 0; i < count; i++) {
if (is_zero_ip(ip_list[i]))
continue;
if (name_status_find(domain, 0x1c, 0x20, ip_list[i], srv_name)) {
result = check_negative_conn_cache( domain, srv_name );
if ( NT_STATUS_IS_OK(result) ) {
dc_ip = ip_list[i];
goto done;
}
}
}
SAFE_FREE(ip_list);
return False;
done:
/* We have the netbios name and IP address of a domain controller.
Ideally we should sent a SAMLOGON request to determine whether
the DC is alive and kicking. If we can catch a dead DC before
performing a cli_connect() we can avoid a 30-second timeout. */
DEBUG(3, ("rpc_find_dc: Returning DC %s (%s) for domain %s\n", srv_name,
inet_ntoa(dc_ip), domain));
*ip_out = dc_ip;
SAFE_FREE(ip_list);
return True;
}
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