Add basic caching support.

3 files changed, 244 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index beb152c..ceb4bcf 100644
--- a/Makefile
+++ b/Makefile
@@ -5,8 +5,8 @@ LIBMINOR = 0
 
 LIBNAME = libdnsldap.so.$(LIBMAJOR).$(LIBMINOR).0
 LIBSONAME = libdnsldap.so.$(LIBMAJOR)
-OBJS  = ldap_driver.o semaphore.o ldap_convert.o ldap_helper.o log.o rdlist.o
-OBJS += settings.o str.o zone_manager.o
+OBJS  = cache.o ldap_driver.o semaphore.o ldap_convert.o ldap_helper.o log.o
+OBJS += rdlist.o settings.o str.o zone_manager.o
 
 CFLAGS := -Wall -Wextra -pedantic -std=c99 -g -fPIC $(CFLAGS)
 
diff --git a/cache.c b/cache.c
new file mode 100644
index 0000000..40c25ce
--- /dev/null
+++ b/cache.c
@@ -0,0 +1,190 @@
+/* Authors: Martin Nagy <mnagy@redhat.com>
+ *
+ * Copyright (C) 2009  Red Hat
+ * see file 'COPYING' for use and warranty information
+ *
+ * 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; version 2 only
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <isc/mem.h>
+#include <isc/result.h>
+#include <isc/util.h>
+
+#include <dns/rbt.h>
+#include <dns/result.h>
+
+#include <string.h>
+
+#include "cache.h"
+#include "ldap_helper.h"
+#include "log.h"
+#include "rdlist.h"
+#include "settings.h"
+#include "util.h"
+
+/* XXX: Locking? */
+struct ldap_cache {
+	isc_mem_t	*mctx;
+	dns_rbt_t	*rbt;
+	/* TODO: Add a timeout period setting. */
+};
+
+typedef struct {
+	isc_mem_t		*mctx;
+	ldapdb_rdatalist_t	rdatalist;
+	/* TODO: Add time of creation for expiration purposes. */
+} cache_node_t;
+
+static void
+cache_node_deleter(void *data, void *deleter_arg)
+{
+	cache_node_t *node = (cache_node_t *)data;
+
+	UNUSED(deleter_arg);
+	REQUIRE(data != NULL);
+
+	ldapdb_rdatalist_destroy(node->mctx, &node->rdatalist);
+	MEM_PUT_AND_DETACH(node);
+}
+
+static isc_result_t
+cache_node_create(isc_mem_t *mctx, ldapdb_rdatalist_t rdatalist,
+		  cache_node_t **nodep)
+{
+	isc_result_t result;
+	cache_node_t *node;
+
+	REQUIRE(mctx != NULL);
+	REQUIRE(nodep != NULL && *nodep == NULL);
+
+	CHECKED_MEM_GET_PTR(mctx, node);
+	ZERO_PTR(node);
+	isc_mem_attach(mctx, &node->mctx);
+	node->rdatalist = rdatalist;
+
+	*nodep = node;
+	return ISC_R_SUCCESS;
+
+cleanup:
+	SAFE_MEM_PUT_PTR(mctx, node);
+
+	return result;
+}
+
+/*
+ * TODO: Add setting saying if we want to enable cache, if not, then
+ * cache->rbt must be set to NULL.
+ */
+isc_result_t
+new_ldap_cache(isc_mem_t *mctx, ldap_cache_t **cachep,
+	       const char * const *argv)
+{
+	isc_result_t result;
+	ldap_cache_t *cache = NULL;
+
+	UNUSED(argv);
+
+	REQUIRE(cachep != NULL && *cachep == NULL);
+
+	CHECKED_MEM_GET_PTR(mctx, cache);
+	ZERO_PTR(cache);
+	isc_mem_attach(mctx, &cache->mctx);
+
+	if (1) {
+		CHECK(dns_rbt_create(mctx, cache_node_deleter, NULL,
+				     &cache->rbt));
+	}
+
+
+	*cachep = cache;
+	return ISC_R_SUCCESS;
+
+cleanup:
+	if (cache != NULL)
+		destroy_ldap_cache(&cache);
+
+	return result;
+}
+
+void
+destroy_ldap_cache(ldap_cache_t **cachep)
+{
+	ldap_cache_t *cache;
+
+	REQUIRE(cachep != NULL && *cachep != NULL);
+
+	cache = *cachep;
+
+	if (cache->rbt)
+		dns_rbt_destroy(&cache->rbt);
+
+	MEM_PUT_AND_DETACH(cache);
+
+	*cachep = NULL;
+}
+
+/* TODO: Implement expiration. */
+isc_result_t
+cached_ldap_rdatalist_get(isc_mem_t *mctx, ldap_cache_t *cache,
+			  ldap_db_t *ldap_db, dns_name_t *name,
+			  ldapdb_rdatalist_t *rdatalist)
+{
+	isc_result_t result;
+	ldapdb_rdatalist_t rdlist;
+	cache_node_t *node = NULL;
+	void *data = NULL;
+	int found = 0;
+	int expired = 0;
+
+	REQUIRE(cache != NULL);
+
+	INIT_LIST(*rdatalist);
+	INIT_LIST(rdlist);
+
+	if (cache->rbt == NULL)
+		return ldapdb_rdatalist_get(mctx, ldap_db, name, rdatalist);
+
+	result = dns_rbt_findname(cache->rbt, name, 0, NULL, &data);
+	if (result == ISC_R_SUCCESS) {
+		found = 1;
+		expired = 0; /* find out if we are expired */
+		node = (cache_node_t *)data;
+		rdlist = node->rdatalist;
+	} else if (result != ISC_R_NOTFOUND && result != DNS_R_PARTIALMATCH) {
+		goto cleanup;
+	}
+
+	if ((found && expired) || !found) {
+		if (found) {
+			CHECK(dns_rbt_deletename(cache->rbt, name, ISC_FALSE));
+			data = NULL; /* ? */
+		}
+		INIT_LIST(rdlist);
+		result = ldapdb_rdatalist_get(mctx, ldap_db, name, &rdlist);
+		if (result != ISC_R_SUCCESS && result != ISC_R_NOTFOUND)
+			goto cleanup;
+		CHECK(cache_node_create(mctx, rdlist, &node));
+		data = (void *)node;
+		CHECK(dns_rbt_addname(cache->rbt, name, data));
+	}
+	CHECK(ldap_rdatalist_copy(mctx, rdlist, rdatalist));
+
+	if (EMPTY(*rdatalist))
+		return ISC_R_NOTFOUND;
+	else
+		return ISC_R_SUCCESS;
+
+cleanup:
+	return result;
+}
diff --git a/cache.h b/cache.h
new file mode 100644
index 0000000..fcffd49
--- /dev/null
+++ b/cache.h
@@ -0,0 +1,52 @@
+/* Authors: Martin Nagy <mnagy@redhat.com>
+ *
+ * Copyright (C) 2009  Red Hat
+ * see file 'COPYING' for use and warranty information
+ *
+ * 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; version 2 only
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _LD_CACHE_H_
+#define _LD_CACHE_H_
+
+#include "ldap_helper.h"
+
+typedef struct ldap_cache ldap_cache_t;
+
+/*
+ * Create a new cache.
+ */
+isc_result_t
+new_ldap_cache(isc_mem_t *mctx, ldap_cache_t **cachep,
+	       const char * const *argv);
+
+/*
+ * Free all resources used up by the cache.
+ */
+void
+destroy_ldap_cache(ldap_cache_t **cachep);
+
+
+/*
+ * If caching is enabled, lookup 'name' in 'cache'. If the record is found and
+ * is not expired, make a copy and return it. If the record is not found or is
+ * expired, look it up in LDAP and cache it.
+ */
+isc_result_t
+cached_ldap_rdatalist_get(isc_mem_t *mctx, ldap_cache_t *cache,
+			  ldap_db_t *ldap_db, dns_name_t *name,
+			  ldapdb_rdatalist_t *rdatalist);
+
+
+#endif /* !_LD_CACHE_H_ */