mirror of
https://github.com/samba-team/samba.git
synced 2025-01-11 05:18:09 +03:00
Marc VanHeyningen
Volker Lendecke
parent
f4e93883c9
commit
d4cbc4408e
@ -6,6 +6,7 @@
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Copyright (C) Tim Potter 2001
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Copyright (C) Andrew Bartlett 2002
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Copyright (C) Gerald (Jerry) Carter 2003
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Copyright (C) Marc VanHeyningen 2008
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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@ -24,168 +25,227 @@
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#include "includes.h"
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#define CONNCACHE_ADDR 1
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#define CONNCACHE_NAME 2
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/**
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* @file
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* Negative connection cache implemented in terms of gencache API
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*
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* The negative connection cache stores names of servers which have
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* been unresponsive so that we don't waste time repeatedly trying
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* to contact them. It used to use an in-memory linked list, but
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* this limited its utility to a single process
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*/
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/* cache entry contains either a server name **or** and IP address as
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the key. This means that a server could have two entries (one for each key) */
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struct failed_connection_cache {
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fstring domain_name;
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fstring controller;
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time_t lookup_time;
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NTSTATUS nt_status;
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struct failed_connection_cache *prev, *next;
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};
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static struct failed_connection_cache *failed_connection_cache;
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/**
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* prefix used for all entries put into the general cache
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*/
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static const char NEGATIVE_CONN_CACHE_PREFIX[] = "NEG_CONN_CACHE";
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/**********************************************************************
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Check for a previously failed connection.
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failed_cache_timeout is an a absolute number of seconds after which
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we should time this out. If failed_cache_timeout == 0 then time out
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immediately. If failed_cache_timeout == -1 then never time out.
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**********************************************************************/
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NTSTATUS check_negative_conn_cache_timeout( const char *domain, const char *server, unsigned int failed_cache_timeout )
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/**
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* Marshalls the domain and server name into the key for the gencache
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* record
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*
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* @param[in] domain required
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* @param[in] server may be a FQDN or an IP address
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* @return the resulting string, which the caller is responsible for
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* SAFE_FREE()ing
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* @retval NULL returned on error
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*/
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static char *negative_conn_cache_keystr(const char *domain, const char *server)
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{
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struct failed_connection_cache *fcc;
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NTSTATUS result = NT_STATUS_UNSUCCESSFUL;
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const char NEGATIVE_CONN_CACHE_KEY_FMT[] = "%s/%s,%s";
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char *keystr = NULL;
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SMB_ASSERT(domain != NULL);
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if (server == NULL)
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server = "";
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/* can't check if we don't have strings */
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if ( !domain || !server )
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return NT_STATUS_OK;
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if (asprintf(&keystr, NEGATIVE_CONN_CACHE_KEY_FMT,
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NEGATIVE_CONN_CACHE_PREFIX, domain, server) == -1)
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DEBUG(0, ("negative_conn_cache_keystr: malloc error\n"));
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for (fcc = failed_connection_cache; fcc; fcc = fcc->next) {
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if (!(strequal(domain, fcc->domain_name) && strequal(server, fcc->controller))) {
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continue; /* no match; check the next entry */
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}
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/* we have a match so see if it is still current */
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if (failed_cache_timeout != (unsigned int)-1) {
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if (failed_cache_timeout == 0 ||
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(time(NULL) - fcc->lookup_time) > (time_t)failed_cache_timeout) {
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/* Cache entry has expired, delete it */
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DEBUG(10, ("check_negative_conn_cache: cache entry expired for %s, %s\n",
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domain, server ));
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DLIST_REMOVE(failed_connection_cache, fcc);
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SAFE_FREE(fcc);
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return NT_STATUS_OK;
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}
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}
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/* The timeout hasn't expired yet so return false */
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DEBUG(10, ("check_negative_conn_cache: returning negative entry for %s, %s\n",
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domain, server ));
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result = fcc->nt_status;
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return result;
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}
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/* end of function means no cache entry */
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return NT_STATUS_OK;
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return keystr;
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}
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/**
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* Marshalls the NT status into a printable value field for the gencache
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* record
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*
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* @param[in] status
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* @return the resulting string, which the caller is responsible for
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* SAFE_FREE()ing
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* @retval NULL returned on error
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*/
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static char *negative_conn_cache_valuestr(NTSTATUS status)
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{
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char *valuestr = NULL;
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if (asprintf(&valuestr, "%x", NT_STATUS_V(status)) == -1)
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DEBUG(0, ("negative_conn_cache_valuestr: malloc error\n"));
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return valuestr;
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}
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/**
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* Un-marshalls the NT status from a printable field for the gencache
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* record
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*
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* @param[in] value The value field from the record
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* @return the decoded NT status
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* @retval NT_STATUS_OK returned on error
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*/
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static NTSTATUS negative_conn_cache_valuedecode(const char *value)
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{
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NTSTATUS result = NT_STATUS_OK;
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SMB_ASSERT(value != NULL);
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if (sscanf(value, "%x", &(NT_STATUS_V(result))) != 1)
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DEBUG(0, ("negative_conn_cache_valuestr: unable to parse "
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"value field '%s'\n", value));
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return result;
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}
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/**
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* Function passed to gencache_iterate to remove any matching items
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* from the list
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*
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* @param[in] key Key to the record found and to be deleted
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* @param[in] value Value to the record (ignored)
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* @param[in] timeout Timeout remaining for the record (ignored)
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* @param[in] dptr Handle for passing additional data (ignored)
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*/
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static void delete_matches(const char *key, const char *value,
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time_t timeout, void *dptr)
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{
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gencache_del(key);
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}
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/**
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* Checks for a given domain/server record in the negative cache
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*
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* @param[in] domain
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* @param[in] server may be either a FQDN or an IP address
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* @return The cached failure status
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* @retval NT_STATUS_OK returned if no record is found or an error occurs
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*/
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NTSTATUS check_negative_conn_cache( const char *domain, const char *server)
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{
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return check_negative_conn_cache_timeout(domain, server, FAILED_CONNECTION_CACHE_TIMEOUT);
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NTSTATUS result = NT_STATUS_OK;
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char *key = NULL;
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char *value = NULL;
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key = negative_conn_cache_keystr(domain, server);
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if (key == NULL)
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goto done;
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if (gencache_get(key, &value, (time_t *) NULL))
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result = negative_conn_cache_valuedecode(value);
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done:
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DEBUG(9,("check_negative_conn_cache returning result %d for domain %s "
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"server %s\n", NT_STATUS_V(result), domain, server));
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SAFE_FREE(key);
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SAFE_FREE(value);
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return result;
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}
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/**********************************************************************
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Add an entry to the failed conneciton cache (aither a name of dotted
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decimal IP
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**********************************************************************/
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void add_failed_connection_entry(const char *domain, const char *server, NTSTATUS result)
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/**
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* Delete any negative cache entry for the given domain/server
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*
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* @param[in] domain
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* @param[in] server may be either a FQDN or an IP address
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*/
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void delete_negative_conn_cache(const char *domain, const char *server)
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{
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struct failed_connection_cache *fcc;
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char *key = NULL;
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key = negative_conn_cache_keystr(domain, server);
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if (key == NULL)
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goto done;
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gencache_del(key);
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DEBUG(9,("delete_negative_conn_cache removing domain %s server %s\n",
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domain, server));
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done:
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SAFE_FREE(key);
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return;
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}
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/**
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* Add an entry to the failed conneciton cache
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*
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* @param[in] domain
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* @param[in] server may be a FQDN or an IP addr in printable form
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* @param[in] result error to cache; must not be NT_STATUS_OK
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*/
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void add_failed_connection_entry(const char *domain, const char *server,
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NTSTATUS result)
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{
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char *key = NULL;
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char *value = NULL;
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SMB_ASSERT(!NT_STATUS_IS_OK(result));
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/* Check we already aren't in the cache. We always have to have
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a domain, but maybe not a specific DC name. */
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for (fcc = failed_connection_cache; fcc; fcc = fcc->next) {
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if ( strequal(fcc->domain_name, domain) && strequal(fcc->controller, server) ) {
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DEBUG(10, ("add_failed_connection_entry: domain %s (%s) already tried and failed\n",
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domain, server ));
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/* Update the failed time. */
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fcc->lookup_time = time(NULL);
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return;
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}
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}
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/* Create negative lookup cache entry for this domain and controller */
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if ( !(fcc = SMB_MALLOC_P(struct failed_connection_cache)) ) {
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DEBUG(0, ("malloc failed in add_failed_connection_entry!\n"));
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return;
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key = negative_conn_cache_keystr(domain, server);
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if (key == NULL) {
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DEBUG(0, ("add_failed_connection_entry: key creation error\n"));
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goto done;
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}
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ZERO_STRUCTP(fcc);
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value = negative_conn_cache_valuestr(result);
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if (value == NULL) {
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DEBUG(0, ("add_failed_connection_entry: value creation error\n"));
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goto done;
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}
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fstrcpy( fcc->domain_name, domain );
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fstrcpy( fcc->controller, server );
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fcc->lookup_time = time(NULL);
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fcc->nt_status = result;
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if (gencache_set(key, value,
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time((time_t *) NULL + FAILED_CONNECTION_CACHE_TIMEOUT)))
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DEBUG(9,("add_failed_connection_entry: added domain %s (%s) "
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"to failed conn cache\n", domain, server ));
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else
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DEBUG(1,("add_failed_connection_entry: failed to add "
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"domain %s (%s) to failed conn cache\n",
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domain, server));
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DEBUG(10,("add_failed_connection_entry: added domain %s (%s) to failed conn cache\n",
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domain, server ));
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DLIST_ADD(failed_connection_cache, fcc);
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done:
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SAFE_FREE(key);
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SAFE_FREE(value);
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return;
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}
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/****************************************************************************
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****************************************************************************/
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/**
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* Deletes all records from the negative connection cache in all domains
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*/
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void flush_negative_conn_cache( void )
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{
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struct failed_connection_cache *fcc;
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fcc = failed_connection_cache;
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while (fcc) {
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struct failed_connection_cache *fcc_next;
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fcc_next = fcc->next;
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DLIST_REMOVE(failed_connection_cache, fcc);
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free(fcc);
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fcc = fcc_next;
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}
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flush_negative_conn_cache_for_domain("*");
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}
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/****************************************************************************
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Remove all negative entries for a domain. Used when going to online state in
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winbindd.
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****************************************************************************/
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/**
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* Deletes all records for a specified domain from the negative connection
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* cache
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*
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* @param[in] domain String to match against domain portion of keys, or "*"
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* to match all domains
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*/
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void flush_negative_conn_cache_for_domain(const char *domain)
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{
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struct failed_connection_cache *fcc;
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fcc = failed_connection_cache;
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char *key_pattern = NULL;
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while (fcc) {
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struct failed_connection_cache *fcc_next;
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fcc_next = fcc->next;
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if (strequal(fcc->domain_name, domain)) {
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DEBUG(10,("flush_negative_conn_cache_for_domain: removed server %s "
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" from failed cache for domain %s\n",
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fcc->controller, domain));
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DLIST_REMOVE(failed_connection_cache, fcc);
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free(fcc);
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}
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fcc = fcc_next;
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key_pattern = negative_conn_cache_keystr(domain,"*");
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if (key_pattern == NULL) {
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DEBUG(0, ("flush_negative_conn_cache_for_domain: "
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"key creation error\n"));
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goto done;
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}
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gencache_iterate(delete_matches, (void *) NULL, key_pattern);
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DEBUG(8, ("flush_negative_conn_cache_for_domain: flushed domain %s\n",
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domain));
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done:
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SAFE_FREE(key_pattern);
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return;
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}
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