Merge of netbios namecache code from APPLIANCE_HEAD.

Tridge suggested a generic caching mechanism for Samba to avoid the
proliferation of little cache files hanging around limpet like in the
locks directory.  Someone should probably implement this at some
stage.
(This used to be commit dad31483b3bd1790356ef1e40ac62624a403bce8)

1 files changed, 252 insertions, 0 deletions

diff --git a/source3/libsmb/namecache.c b/source3/libsmb/namecache.c
new file mode 100644
index 0000000000..fc09d8eac2
--- /dev/null
+++ b/source3/libsmb/namecache.c
@@ -0,0 +1,252 @@
+/* 
+   Unix SMB/CIFS implementation.
+
+   NetBIOS name cache module.
+
+   Copyright (C) Tim Potter, 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"
+
+static BOOL done_namecache_init;
+static BOOL enable_namecache;
+static TDB_CONTEXT *namecache_tdb;
+
+struct nc_value {
+	time_t expiry;		     /* When entry expires */
+	int count;		     /* Number of addresses */
+	struct in_addr ip_list[0];   /* Address list */
+};
+
+/* Initialise namecache system */
+
+void namecache_enable(void)
+{
+	/* Check if we have been here before, or name caching disabled
+           by setting the name cache timeout to zero. */ 
+
+	if (done_namecache_init)
+		return;
+
+	done_namecache_init = True;
+
+	if (lp_name_cache_timeout() == 0) {
+		DEBUG(5, ("namecache_init: disabling netbios name cache\n"));
+		return;
+	}
+
+	/* Open namecache tdb in read/write or readonly mode */
+
+	namecache_tdb = tdb_open_log(
+		lock_path("namecache.tdb"), 0,
+		TDB_DEFAULT, O_RDWR | O_CREAT, 0644);
+
+	if (!namecache_tdb) {
+		DEBUG(5, ("namecache_init: could not open %s\n",
+			  lock_path("namecache.tdb")));
+		return;
+	}
+
+	DEBUG(5, ("namecache_init: enabling netbios namecache, timeout %d "
+		  "seconds\n", lp_name_cache_timeout()));
+
+	enable_namecache = True;
+}
+
+/* Return a key for a name and name type.  The caller must free
+   retval.dptr when finished. */
+
+static TDB_DATA namecache_key(const char *name, int name_type)
+{
+	TDB_DATA retval;
+	char *keystr;
+
+	asprintf(&keystr, "%s#%02X", strupper_static(name), name_type);
+
+	retval.dsize = strlen(keystr) + 1;
+	retval.dptr = keystr;
+
+	return retval;
+}
+
+/* Return a data value for an IP list.  The caller must free
+   retval.dptr when finished. */
+
+static TDB_DATA namecache_value(struct in_addr *ip_list, int num_names, 
+				time_t expiry)
+{
+	TDB_DATA retval;
+	struct nc_value *value;
+	int size;
+
+	size = sizeof(struct nc_value) + sizeof(struct in_addr) *
+		num_names;
+
+	value = (struct nc_value *)malloc(size);
+		
+	value->expiry = expiry;
+	value->count = num_names;
+
+	memcpy(value->ip_list, ip_list, num_names * sizeof(struct in_addr));
+
+	retval.dptr = (char *)value;
+	retval.dsize = size;
+
+	return retval;
+}
+
+/* Store a name in the name cache */
+
+void namecache_store(const char *name, int name_type,
+		     int num_names, struct in_addr *ip_list)
+{
+	TDB_DATA key, value;
+	time_t expiry;
+	int i;
+
+	if (!enable_namecache)
+		return;
+
+	DEBUG(5, ("namecache_store: storing %d address%s for %s#%02x: ",
+		  num_names, num_names == 1 ? "": "es", name, name_type));
+
+	for (i = 0; i < num_names; i++) 
+		DEBUGADD(5, ("%s%s", inet_ntoa(ip_list[i]),
+			     i == (num_names - 1) ? "" : ", "));
+
+	DEBUGADD(5, ("\n"));
+
+	key = namecache_key(name, name_type);
+
+	/* Cache pdc location or dc lists for only a little while
+	   otherwise if we lock on to a bad DC we can potentially be
+	   out of action for the entire cache timeout time! */
+
+	if (name_type != 0x1b || name_type != 0x1c)
+		expiry = time(NULL) + 10;
+	else
+		expiry = time(NULL) + lp_name_cache_timeout();
+
+	value = namecache_value(ip_list, num_names, expiry);
+
+	tdb_store(namecache_tdb, key, value, TDB_REPLACE);
+
+	free(key.dptr);
+	free(value.dptr);
+}
+
+/* Look up a name in the name cache.  Return a mallocated list of IP
+   addresses if the name is contained in the cache. */
+
+BOOL namecache_fetch(const char *name, int name_type, struct in_addr **ip_list,
+		     int *num_names)
+{
+	TDB_DATA key, value;
+	struct nc_value *data;
+	time_t now;
+	int i;
+
+	if (!enable_namecache)
+		return False;
+
+	/* Read value */
+
+	key = namecache_key(name, name_type);
+
+	value = tdb_fetch(namecache_tdb, key);
+	
+	if (!value.dptr) {
+		DEBUG(5, ("namecache_fetch: %s#%02x not found\n",
+			  name, name_type));
+		goto done;
+	}
+
+	data = (struct nc_value *)value.dptr;
+
+	/* Check expiry time */
+
+	now = time(NULL);
+
+	if (now > data->expiry) {
+
+		DEBUG(5, ("namecache_fetch: entry for %s#%02x expired\n",
+			  name, name_type));
+
+		tdb_delete(namecache_tdb, key);
+
+		value = tdb_null;
+
+		goto done;
+	}
+
+	if ((data->expiry - now) > lp_name_cache_timeout()) {
+
+		/* Someone may have changed the system time on us */
+
+		DEBUG(5, ("namecache_fetch: entry for %s#%02x has bad expiry\n",
+			  name, name_type));
+
+		tdb_delete(namecache_tdb, key);
+
+		value = tdb_null;
+
+		goto done;
+	}
+
+	/* Extract and return namelist */
+
+	*ip_list = (struct in_addr *)malloc(
+		sizeof(struct in_addr) * data->count);
+	
+	memcpy(*ip_list, data->ip_list, sizeof(struct in_addr) *
+	       data->count);
+
+	*num_names = data->count;
+
+	DEBUG(5, ("namecache_fetch: returning %d address%s for %s#%02x: ",
+		  *num_names, *num_names == 1 ? "" : "es", name, name_type));
+
+	for (i = 0; i < *num_names; i++)
+		DEBUGADD(5, ("%s%s", inet_ntoa((*ip_list)[i]),
+			     i == (*num_names - 1) ? "" : ", "));
+
+	DEBUGADD(5, ("\n"));
+
+done:
+	SAFE_FREE(key.dptr);
+	SAFE_FREE(value.dptr);
+
+	return value.dsize > 0;
+}
+
+/* Flush all names from the name cache */
+
+void namecache_flush(void)
+{
+	int result;
+
+	if (!namecache_tdb)
+		return;
+
+	result = tdb_traverse(namecache_tdb, tdb_traverse_delete_fn, NULL);
+
+	if (result == -1)
+		DEBUG(5, ("namecache_flush: error deleting cache entries\n"));
+	else
+		DEBUG(5, ("namecache_flush: deleted %d cache entr%s\n", 
+			  result, result == 1 ? "y" : "ies"));
+}