diff --git a/bin/named/main.c b/bin/named/main.c

index aa6575a..8030e3d 100644

--- a/bin/named/main.c

+++ b/bin/named/main.c

@@ -44,6 +44,7 @@

 #include <isccc/result.h>

 #include <dns/dispatch.h>

+#include <dns/dynamic_db.h>

 #include <dns/name.h>

 #include <dns/result.h>

 #include <dns/view.h>

@@ -778,6 +779,8 @@ cleanup(void) {

 	dlz_drivers_clear();

 #endif

+	dns_dynamic_db_cleanup();

+

 	dns_name_destroy();

 	isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL, NS_LOGMODULE_MAIN,

diff --git a/bin/named/server.c b/bin/named/server.c

index 31b2761..b76f3ce 100644

--- a/bin/named/server.c

+++ b/bin/named/server.c

@@ -56,6 +56,7 @@

 #ifdef DLZ

 #include <dns/dlz.h>

 #endif

+#include <dns/dynamic_db.h>

 #include <dns/forward.h>

 #include <dns/journal.h>

 #include <dns/keytable.h>

@@ -849,6 +850,72 @@ configure_peer(const cfg_obj_t *cpeer, isc_mem_t *mctx, dns_peer_t **peerp) {

 }

 static isc_result_t

+configure_dynamic_db(const cfg_obj_t *dynamic_db, isc_mem_t *mctx,

+		     dns_view_t *view, dns_zonemgr_t *zmgr)

+{

+	isc_result_t result;

+	const cfg_obj_t *obj;

+	const cfg_obj_t *options;

+	const cfg_listelt_t *element;

+	const char *name;

+	const char *libname;

+	const char **argv = NULL;

+	unsigned int i;

+	unsigned int len;

+

+	/* Get the name of the database. */

+	obj = cfg_tuple_get(dynamic_db, "name");

+	name = cfg_obj_asstring(obj);

+

+	/* Get options. */

+	options = cfg_tuple_get(dynamic_db, "options");

+

+	/* Get library name. */

+	obj = NULL;

+	CHECK(cfg_map_get(options, "library", &obj));

+	libname = cfg_obj_asstring(obj);

+

+	/* Create a list of arguments. */

+	obj = NULL;

+	result = cfg_map_get(options, "arg", &obj);

+	if (result == ISC_R_NOTFOUND)

+		len = 0;

+	else if (result == ISC_R_SUCCESS)

+		len = cfg_list_length(obj, isc_boolean_false);

+	else

+		goto cleanup;

+

+	/* Account for the last terminating NULL. */

+	len++;

+

+	argv = isc_mem_allocate(mctx, len * sizeof(const char *));

+	if (argv == NULL) {

+		result = ISC_R_NOMEMORY;

+		goto cleanup;

+	}

+	for (element = cfg_list_first(obj), i = 0;

+	     element != NULL;

+	     element = cfg_list_next(element), i++)

+	{

+		REQUIRE(i < len);

+

+		obj = cfg_listelt_value(element);

+		argv[i] = cfg_obj_asstring(obj);

+	}

+	REQUIRE(i < len);

+	argv[i] = NULL;

+

+	CHECK(dns_dynamic_db_load(libname, name, mctx, argv, view, zmgr));

+

+cleanup:

+	if (argv != NULL)

+		isc_mem_free(mctx, argv);

+

+	return result;

+}

+

+

+static isc_result_t

 disable_algorithms(const cfg_obj_t *disabled, dns_resolver_t *resolver) {

 	isc_result_t result;

 	const cfg_obj_t *algorithms;

@@ -999,6 +1066,7 @@ configure_view(dns_view_t *view, const cfg_obj_t *config,

 	unsigned int dlzargc;

 	char **dlzargv;

 #endif

+	const cfg_obj_t *dynamic_db_list;

 	const cfg_obj_t *disabled;

 	const cfg_obj_t *obj;

 	const cfg_listelt_t *element;

@@ -1171,6 +1239,22 @@ configure_view(dns_view_t *view, const cfg_obj_t *config,

 #endif

 	/*

+	 * Configure dynamic databases.

+	 */

+	dynamic_db_list = NULL;

+	if (voptions != NULL)

+		(void)cfg_map_get(voptions, "dynamic-db", &dynamic_db_list);

+	else

+		(void)cfg_map_get(config, "dynamic-db", &dynamic_db_list);

+	for (element = cfg_list_first(dynamic_db_list);

+	     element != NULL;

+	     element = cfg_list_next(element))

+	{

+		obj = cfg_listelt_value(element);

+		CHECK(configure_dynamic_db(obj, mctx, view, ns_g_server->zonemgr));

+	}

+

+	/*

 	 * Configure the view's cache.  Try to reuse an existing

 	 * cache if possible, otherwise create a new cache.

 	 * Note that the ADB is not preserved in either case.

diff --git a/lib/dns/Makefile.in b/lib/dns/Makefile.in

index ef5c12a..0f7abba 100644

--- a/lib/dns/Makefile.in

+++ b/lib/dns/Makefile.in

@@ -57,7 +57,8 @@ DSTOBJS =	@DST_EXTRA_OBJS@ \

 DNSOBJS =	acache.@O@ acl.@O@ adb.@O@ byaddr.@O@ \

 		cache.@O@ callbacks.@O@ compress.@O@ \

 		db.@O@ dbiterator.@O@ dbtable.@O@ diff.@O@ dispatch.@O@ \

-		dlz.@O@ dnssec.@O@ ds.@O@ forward.@O@ iptable.@O@ journal.@O@ \

+		dlz.@O@ dnssec.@O@ ds.@O@ dynamic_db.@O@ forward.@O@ \

+		iptable.@O@ journal.@O@ \

 		keytable.@O@ lib.@O@ log.@O@ lookup.@O@ \

 		master.@O@ masterdump.@O@ message.@O@ \

 		name.@O@ ncache.@O@ nsec.@O@ nsec3.@O@ order.@O@ peer.@O@ portlist.@O@ \

@@ -83,7 +84,7 @@ DSTSRCS =	@DST_EXTRA_SRCS@ \

 DNSSRCS =	acache.c acl.c adb.c byaddr.c \

 		cache.c callbacks.c compress.c \

 		db.c dbiterator.c dbtable.c diff.c dispatch.c \

-		dlz.c dnssec.c ds.c forward.c iptable.c journal.c \

+		dlz.c dnssec.c ds.c dynamic_db.c forward.c iptable.c journal.c \

 		keytable.c lib.c log.c lookup.c \

 		master.c masterdump.c message.c \

 		name.c ncache.c nsec.c nsec3.c order.c peer.c portlist.c \

diff --git a/lib/dns/dynamic_db.c b/lib/dns/dynamic_db.c

new file mode 100644

index 0000000..b95b1fe

--- /dev/null

+++ b/lib/dns/dynamic_db.c

@@ -0,0 +1,240 @@

+/*

+ * Copyright (C) 2004-2009  Internet Systems Consortium, Inc. ("ISC")

+ * Copyright (C) 1996-2003  Internet Software Consortium.

+ *

+ * Permission to use, copy, modify, and/or distribute this software for any

+ * purpose with or without fee is hereby granted, provided that the above

+ * copyright notice and this permission notice appear in all copies.

+ *

+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH

+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY

+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,

+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM

+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE

+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR

+ * PERFORMANCE OF THIS SOFTWARE.

+ */

+

+

+#include <config.h>

+

+#include <isc/mem.h>

+#include <isc/mutex.h>

+#include <isc/once.h>

+#include <isc/result.h>

+#include <isc/types.h>

+#include <isc/util.h>

+

+#include <dns/dynamic_db.h>

+#include <dns/log.h>

+#include <dns/types.h>

+

+

+#if HAVE_DLFCN_H

+#include <dlfcn.h>

+#endif

+

+#define CHECK(op)						\

+	do { result = (op);					\

+		if (result != ISC_R_SUCCESS) goto cleanup;	\

+	} while (0)

+

+

+typedef isc_result_t (*register_func_t)(isc_mem_t *mctx, const char *name,

+		const char * const *argv, dns_view_t *view,

+		dns_zonemgr_t *zmgr);

+typedef void (*destroy_func_t)(void);

+

+typedef struct dyndb_implementation dyndb_implementation_t;

+

+struct dyndb_implementation {

+	isc_mem_t			*mctx;

+	void				*handle;

+	register_func_t			register_function;

+	destroy_func_t			destroy_function;

+	LINK(dyndb_implementation_t)	link;

+};

+

+/* List of implementations. Locked by dyndb_lock. */

+static LIST(dyndb_implementation_t) dyndb_implementations;

+/* Locks dyndb_implementations. */

+static isc_mutex_t dyndb_lock;

+static isc_once_t once = ISC_ONCE_INIT;

+

+static void

+dyndb_initialize(void) {

+	RUNTIME_CHECK(isc_mutex_init(&dyndb_lock) == ISC_R_SUCCESS);

+	INIT_LIST(dyndb_implementations);

+}

+

+

+#if HAVE_DLFCN_H

+static isc_result_t

+load_symbol(void *handle, const char *symbol_name, void **symbolp)

+{

+	const char *errmsg;

+	void *symbol;

+

+	REQUIRE(handle != NULL);

+	REQUIRE(symbolp != NULL && *symbolp == NULL);

+

+	symbol = dlsym(handle, symbol_name);

+	if (symbol == NULL) {

+		errmsg = dlerror();

+		if (errmsg == NULL)

+			errmsg = "returned function pointer is NULL";

+		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,

+			      DNS_LOGMODULE_DYNDB, ISC_LOG_ERROR,

+			      "failed to lookup symbol %s: %s",

+			      symbol_name, errmsg);

+		return ISC_R_FAILURE;

+	}

+	dlerror();

+

+	*symbolp = symbol;

+

+	return ISC_R_SUCCESS;

+}

+

+static isc_result_t

+load_library(isc_mem_t *mctx, const char *filename, dyndb_implementation_t **impp)

+{

+	isc_result_t result;

+	void *handle;

+	dyndb_implementation_t *imp;

+	register_func_t register_function = NULL;

+	destroy_func_t destroy_function = NULL;

+

+	REQUIRE(impp != NULL && *impp == NULL);

+

+	handle = dlopen(filename, RTLD_LAZY);

+	if (handle == NULL) {

+		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,

+			      DNS_LOGMODULE_DYNDB, ISC_LOG_ERROR,

+			      "failed to dynamically load driver '%s': %s",

+			      filename, dlerror());

+		result = ISC_R_FAILURE;

+		goto cleanup;

+	}

+	dlerror();

+

+	CHECK(load_symbol(handle, "dynamic_driver_init",

+			  (void **)&register_function));

+	CHECK(load_symbol(handle, "dynamic_driver_destroy",

+			  (void **)&destroy_function));

+

+	imp = isc_mem_get(mctx, sizeof(dyndb_implementation_t));

+	if (imp == NULL) {

+		result = ISC_R_NOMEMORY;

+		goto cleanup;

+	}

+

+	imp->mctx = NULL;

+	isc_mem_attach(mctx, &imp->mctx);

+	imp->handle = handle;

+	imp->register_function = register_function;

+	imp->destroy_function = destroy_function;

+	INIT_LINK(imp, link);

+

+	*impp = imp;

+

+	return ISC_R_SUCCESS;

+

+cleanup:

+	if (handle != NULL)

+		dlclose(handle);

+

+	return result;

+}

+

+static void

+unload_library(dyndb_implementation_t **impp)

+{

+	dyndb_implementation_t *imp;

+

+	REQUIRE(impp != NULL && *impp != NULL);

+

+	imp = *impp;

+

+	isc_mem_putanddetach(&imp->mctx, imp, sizeof(dyndb_implementation_t));

+

+	*impp = NULL;

+}

+

+#else	/* HAVE_DLFCN_H */

+static isc_result_t

+load_library(isc_mem_t *mctx, const char *filename, dyndb_implementation_t **impp)

+{

+	UNUSED(mctx);

+	UNUSED(filename);

+	UNUSED(impp);

+

+	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_DYNDB,

+		      ISC_LOG_ERROR,

+		      "dynamic database support is not implemented")

+

+	return ISC_R_NOTIMPLEMENTED;

+}

+

+static void

+unload_library(dyndb_implementation_t **impp)

+{

+	dyndb_implementation_t *imp;

+

+	REQUIRE(impp != NULL && *impp != NULL);

+

+	imp = *impp;

+

+	isc_mem_putanddetach(&imp->mctx, imp, sizeof(dyndb_implementation_t));

+

+	*impp = NULL;

+}

+#endif	/* HAVE_DLFCN_H */

+

+isc_result_t

+dns_dynamic_db_load(const char *libname, const char *name, isc_mem_t *mctx,

+		    const char * const *argv, dns_view_t *view,

+		    dns_zonemgr_t *zmgr)

+{

+	isc_result_t result;

+	dyndb_implementation_t *implementation = NULL;

+

+	RUNTIME_CHECK(isc_once_do(&once, dyndb_initialize) == ISC_R_SUCCESS);

+

+	CHECK(load_library(mctx, libname, &implementation));

+	CHECK(implementation->register_function(mctx, name, argv, view, zmgr));

+

+	LOCK(&dyndb_lock);

+	APPEND(dyndb_implementations, implementation, link);

+	UNLOCK(&dyndb_lock);

+

+	return ISC_R_SUCCESS;

+

+cleanup:

+	if (implementation != NULL)

+		unload_library(&implementation);

+

+	return result;

+}

+

+void

+dns_dynamic_db_cleanup(void)

+{

+	dyndb_implementation_t *elem;

+	dyndb_implementation_t *next;

+

+	RUNTIME_CHECK(isc_once_do(&once, dyndb_initialize) == ISC_R_SUCCESS);

+

+	LOCK(&dyndb_lock);

+	elem = HEAD(dyndb_implementations);

+	while (elem != NULL) {

+		next = NEXT(elem, link);

+		UNLINK(dyndb_implementations, elem, link);

+		elem->destroy_function();

+		unload_library(&elem);

+		elem = next;

+	}

+	UNLOCK(&dyndb_lock);

+

+	isc_mutex_destroy(&dyndb_lock);

+}

diff --git a/lib/dns/include/dns/Makefile.in b/lib/dns/include/dns/Makefile.in

index e9e049e..27fdc45 100644

--- a/lib/dns/include/dns/Makefile.in

+++ b/lib/dns/include/dns/Makefile.in

@@ -23,7 +23,7 @@ top_srcdir =	@top_srcdir@

 HEADERS =	acl.h adb.h byaddr.h cache.h callbacks.h \

 		cert.h compress.h \

-		db.h dbiterator.h dbtable.h diff.h dispatch.h dlz.h \

+		db.h dbiterator.h dbtable.h diff.h dispatch.h dlz.h dynamic_db.h \

 		dnssec.h ds.h events.h fixedname.h iptable.h journal.h keyflags.h \

 		keytable.h keyvalues.h lib.h log.h master.h masterdump.h \

 		message.h name.h ncache.h \

diff --git a/lib/dns/include/dns/dynamic_db.h b/lib/dns/include/dns/dynamic_db.h

new file mode 100644

index 0000000..03339e6

--- /dev/null

+++ b/lib/dns/include/dns/dynamic_db.h

@@ -0,0 +1,32 @@

+/*

+ * Copyright (C) 2004-2009  Internet Systems Consortium, Inc. ("ISC")

+ * Copyright (C) 1996-2003  Internet Software Consortium.

+ *

+ * Permission to use, copy, modify, and/or distribute this software for any

+ * purpose with or without fee is hereby granted, provided that the above

+ * copyright notice and this permission notice appear in all copies.

+ *

+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH

+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY

+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,

+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM

+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE

+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR

+ * PERFORMANCE OF THIS SOFTWARE.

+ */

+

+

+#ifndef DYNAMIC_DB_H

+#define DYNAMIC_DB_H

+

+#include <isc/types.h>

+

+#include <dns/types.h>

+

+isc_result_t dns_dynamic_db_load(const char *libname, const char *name,

+				 isc_mem_t *mctx, const char * const *argv,

+				 dns_view_t *view, dns_zonemgr_t *zmgr);

+

+void dns_dynamic_db_cleanup(void);

+

+#endif

diff --git a/lib/dns/include/dns/log.h b/lib/dns/include/dns/log.h

index 5adcedd..e171028 100644

--- a/lib/dns/include/dns/log.h

+++ b/lib/dns/include/dns/log.h

@@ -73,6 +73,7 @@ LIBDNS_EXTERNAL_DATA extern isc_logmodule_t dns_modules[];

 #define DNS_LOGMODULE_HINTS		(&dns_modules[24])

 #define DNS_LOGMODULE_ACACHE		(&dns_modules[25])

 #define DNS_LOGMODULE_DLZ		(&dns_modules[26])

+#define DNS_LOGMODULE_DYNDB		(&dns_modules[27])

 ISC_LANG_BEGINDECLS

diff --git a/lib/dns/log.c b/lib/dns/log.c

index 7551e15..b9864eb 100644

--- a/lib/dns/log.c

+++ b/lib/dns/log.c

@@ -79,6 +79,7 @@ LIBDNS_EXTERNAL_DATA isc_logmodule_t dns_modules[] = {

 	{ "dns/hints",		0 },

 	{ "dns/acache",		0 },

 	{ "dns/dlz",		0 },

+	{ "dns/dynamic_db",	0 },

 	{ NULL, 		0 }

 };

diff --git a/lib/isccfg/namedconf.c b/lib/isccfg/namedconf.c

index 0610489..a1dba32 100644

--- a/lib/isccfg/namedconf.c

+++ b/lib/isccfg/namedconf.c

@@ -78,6 +78,7 @@ static cfg_type_t cfg_type_controls;

 static cfg_type_t cfg_type_controls_sockaddr;

 static cfg_type_t cfg_type_destinationlist;

 static cfg_type_t cfg_type_dialuptype;

+static cfg_type_t cfg_type_dynamic_db;

 static cfg_type_t cfg_type_ixfrdifftype;

 static cfg_type_t cfg_type_key;

 static cfg_type_t cfg_type_logfile;

@@ -651,6 +652,7 @@ namedconf_or_view_clauses[] = {

 	{ "zone", &cfg_type_zone, CFG_CLAUSEFLAG_MULTI },

 	/* only 1 DLZ per view allowed */

 	{ "dlz", &cfg_type_dynamically_loadable_zones, 0 },

+	{ "dynamic-db", &cfg_type_dynamic_db, CFG_CLAUSEFLAG_MULTI },

 	{ "server", &cfg_type_server, CFG_CLAUSEFLAG_MULTI },

 	{ "trusted-keys", &cfg_type_trustedkeys, CFG_CLAUSEFLAG_MULTI },

 	{ NULL, NULL, 0 }

@@ -1365,6 +1367,40 @@ static cfg_type_t cfg_type_dialuptype = {

 	&cfg_rep_string, dialup_enums

 };

+/*

+ * Dynamic database clauses.

+ */

+

+static cfg_clausedef_t

+dynamic_db_clauses[] = {

+	{ "library", &cfg_type_qstring, 0 },

+	{ "arg", &cfg_type_qstring, CFG_CLAUSEFLAG_MULTI },

+	{ NULL, NULL, 0 }

+};

+

+static cfg_clausedef_t *

+dynamic_db_clausesets[] = {

+	dynamic_db_clauses,

+	NULL

+};

+

+static cfg_type_t cfg_type_dynamic_db_opts = {

+	"dynamically_loadable_zones_opts", cfg_parse_map,

+	cfg_print_map, cfg_doc_map, &cfg_rep_map,

+	dynamic_db_clausesets

+};

+

+static cfg_tuplefielddef_t dynamic_db_fields[] = {

+	{ "name", &cfg_type_astring, 0 },

+	{ "options", &cfg_type_dynamic_db_opts, 0 },

+	{ NULL, NULL, 0 }

+};

+

+static cfg_type_t cfg_type_dynamic_db = {

+	"dynamic_db", cfg_parse_tuple, cfg_print_tuple, cfg_doc_tuple,

+	&cfg_rep_tuple, dynamic_db_fields

+};

+

 static const char *notify_enums[] = { "explicit", "master-only", NULL };

 static isc_result_t

 parse_notify_type(cfg_parser_t *pctx, const cfg_type_t *type, cfg_obj_t **ret) {