Add support for runtime loading of database backends.

6 files changed, 144 insertions, 3 deletions

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..fcee6a5
--- /dev/null
+++ b/lib/dns/dynamic_db.c
@@ -0,0 +1,108 @@
+/*
+ * 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 <isc/result.h>
+#include <isc/types.h>
+#include <isc/util.h>
+
+#include <dns/dynamic_db.h>
+#include <dns/log.h>
+#include <dns/types.h>
+
+
+/* TODO: Adjust configure.ac accordingly. */
+#define HAVE_DLOPEN 1
+
+#if HAVE_DLOPEN
+#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);
+
+#if HAVE_DLOPEN
+static isc_result_t
+load_library(const char *filename, register_func_t *register_function)
+{
+	isc_result_t result;
+	void *handle;	/* XXX: We don't keep the handle around. Should we? */
+	const char *errmsg;
+
+	REQUIRE(register_function != NULL && *register_function == 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());
+		CHECK(ISC_R_FAILURE);
+	}
+	dlerror();
+
+	*register_function = dlsym(handle, "dynamic_driver_init");
+	if (*register_function == 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 dynamic_driver_init from %s: %s",
+			      filename, errmsg);
+		CHECK(ISC_R_FAILURE);
+	}
+	dlerror();
+
+	return ISC_R_SUCCESS;
+
+cleanup:
+	if (handle != NULL)
+		dlclose(handle);
+	*register_function = NULL;
+
+	return result;
+}
+#else
+static isc_result_t
+load_library(const char *filename, register_func_t *register_function)
+{
+	UNUSED(filename);
+	UNUSED(register_function);
+
+	return ISC_R_NOTIMPLEMENTED;
+}
+#endif
+
+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)
+{
+	isc_result_t result;
+	register_func_t register_func = NULL;
+
+	CHECK(load_library(libname, &register_func));
+	CHECK(register_func(mctx, name, argv, view));
+
+cleanup:
+	return result;
+}
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..c37fb83
--- /dev/null
+++ b/lib/dns/include/dns/dynamic_db.h
@@ -0,0 +1,30 @@
+/*
+ * 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);
+
+
+#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 }
 };