1 files changed, 249 insertions, 0 deletions
diff --git a/lib/dns/dbtable.c b/lib/dns/dbtable.c
new file mode 100644
index 0000000..e36594b
--- /dev/null
+++ b/lib/dns/dbtable.c
@@ -0,0 +1,249 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0.  If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#include <stdbool.h>
+
+#include <isc/mem.h>
+#include <isc/rwlock.h>
+#include <isc/util.h>
+
+#include <dns/db.h>
+#include <dns/dbtable.h>
+#include <dns/rbt.h>
+#include <dns/result.h>
+
+struct dns_dbtable {
+	/* Unlocked. */
+	unsigned int magic;
+	isc_mem_t *mctx;
+	dns_rdataclass_t rdclass;
+	isc_rwlock_t tree_lock;
+	/* Protected by atomics */
+	isc_refcount_t references;
+	/* Locked by tree_lock. */
+	dns_rbt_t *rbt;
+	dns_db_t *default_db;
+};
+
+#define DBTABLE_MAGIC	       ISC_MAGIC('D', 'B', '-', '-')
+#define VALID_DBTABLE(dbtable) ISC_MAGIC_VALID(dbtable, DBTABLE_MAGIC)
+
+static void
+dbdetach(void *data, void *arg) {
+	dns_db_t *db = data;
+
+	UNUSED(arg);
+
+	dns_db_detach(&db);
+}
+
+isc_result_t
+dns_dbtable_create(isc_mem_t *mctx, dns_rdataclass_t rdclass,
+		   dns_dbtable_t **dbtablep) {
+	dns_dbtable_t *dbtable;
+	isc_result_t result;
+
+	REQUIRE(mctx != NULL);
+	REQUIRE(dbtablep != NULL && *dbtablep == NULL);
+
+	dbtable = isc_mem_get(mctx, sizeof(*dbtable));
+
+	dbtable->rbt = NULL;
+	result = dns_rbt_create(mctx, dbdetach, NULL, &dbtable->rbt);
+	if (result != ISC_R_SUCCESS) {
+		goto clean1;
+	}
+
+	isc_rwlock_init(&dbtable->tree_lock, 0, 0);
+	dbtable->default_db = NULL;
+	dbtable->mctx = NULL;
+	isc_mem_attach(mctx, &dbtable->mctx);
+	dbtable->rdclass = rdclass;
+	dbtable->magic = DBTABLE_MAGIC;
+	isc_refcount_init(&dbtable->references, 1);
+
+	*dbtablep = dbtable;
+
+	return (ISC_R_SUCCESS);
+
+clean1:
+	isc_mem_putanddetach(&mctx, dbtable, sizeof(*dbtable));
+
+	return (result);
+}
+
+static void
+dbtable_free(dns_dbtable_t *dbtable) {
+	/*
+	 * Caller must ensure that it is safe to call.
+	 */
+
+	RWLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+
+	if (dbtable->default_db != NULL) {
+		dns_db_detach(&dbtable->default_db);
+	}
+
+	dns_rbt_destroy(&dbtable->rbt);
+
+	RWUNLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+
+	isc_rwlock_destroy(&dbtable->tree_lock);
+
+	dbtable->magic = 0;
+
+	isc_mem_putanddetach(&dbtable->mctx, dbtable, sizeof(*dbtable));
+}
+
+void
+dns_dbtable_attach(dns_dbtable_t *source, dns_dbtable_t **targetp) {
+	REQUIRE(VALID_DBTABLE(source));
+	REQUIRE(targetp != NULL && *targetp == NULL);
+
+	isc_refcount_increment(&source->references);
+
+	*targetp = source;
+}
+
+void
+dns_dbtable_detach(dns_dbtable_t **dbtablep) {
+	dns_dbtable_t *dbtable;
+
+	REQUIRE(dbtablep != NULL);
+	dbtable = *dbtablep;
+	*dbtablep = NULL;
+	REQUIRE(VALID_DBTABLE(dbtable));
+
+	if (isc_refcount_decrement(&dbtable->references) == 1) {
+		dbtable_free(dbtable);
+	}
+}
+
+isc_result_t
+dns_dbtable_add(dns_dbtable_t *dbtable, dns_db_t *db) {
+	isc_result_t result;
+	dns_db_t *dbclone;
+
+	REQUIRE(VALID_DBTABLE(dbtable));
+	REQUIRE(dns_db_class(db) == dbtable->rdclass);
+
+	dbclone = NULL;
+	dns_db_attach(db, &dbclone);
+
+	RWLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+	result = dns_rbt_addname(dbtable->rbt, dns_db_origin(dbclone), dbclone);
+	RWUNLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+
+	return (result);
+}
+
+void
+dns_dbtable_remove(dns_dbtable_t *dbtable, dns_db_t *db) {
+	dns_db_t *stored_data = NULL;
+	isc_result_t result;
+	dns_name_t *name;
+
+	REQUIRE(VALID_DBTABLE(dbtable));
+
+	name = dns_db_origin(db);
+
+	/*
+	 * There is a requirement that the association of name with db
+	 * be verified.  With the current rbt.c this is expensive to do,
+	 * because effectively two find operations are being done, but
+	 * deletion is relatively infrequent.
+	 * XXXDCL ... this could be cheaper now with dns_rbt_deletenode.
+	 */
+
+	RWLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+
+	result = dns_rbt_findname(dbtable->rbt, name, 0, NULL,
+				  (void **)(void *)&stored_data);
+
+	if (result == ISC_R_SUCCESS) {
+		INSIST(stored_data == db);
+
+		(void)dns_rbt_deletename(dbtable->rbt, name, false);
+	}
+
+	RWUNLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+}
+
+void
+dns_dbtable_adddefault(dns_dbtable_t *dbtable, dns_db_t *db) {
+	REQUIRE(VALID_DBTABLE(dbtable));
+	REQUIRE(dbtable->default_db == NULL);
+	REQUIRE(dns_name_compare(dns_db_origin(db), dns_rootname) == 0);
+
+	RWLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+
+	dbtable->default_db = NULL;
+	dns_db_attach(db, &dbtable->default_db);
+
+	RWUNLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+}
+
+void
+dns_dbtable_getdefault(dns_dbtable_t *dbtable, dns_db_t **dbp) {
+	REQUIRE(VALID_DBTABLE(dbtable));
+	REQUIRE(dbp != NULL && *dbp == NULL);
+
+	RWLOCK(&dbtable->tree_lock, isc_rwlocktype_read);
+
+	dns_db_attach(dbtable->default_db, dbp);
+
+	RWUNLOCK(&dbtable->tree_lock, isc_rwlocktype_read);
+}
+
+void
+dns_dbtable_removedefault(dns_dbtable_t *dbtable) {
+	REQUIRE(VALID_DBTABLE(dbtable));
+
+	RWLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+
+	dns_db_detach(&dbtable->default_db);
+
+	RWUNLOCK(&dbtable->tree_lock, isc_rwlocktype_write);
+}
+
+isc_result_t
+dns_dbtable_find(dns_dbtable_t *dbtable, const dns_name_t *name,
+		 unsigned int options, dns_db_t **dbp) {
+	dns_db_t *stored_data = NULL;
+	isc_result_t result;
+	unsigned int rbtoptions = 0;
+
+	REQUIRE(dbp != NULL && *dbp == NULL);
+
+	if ((options & DNS_DBTABLEFIND_NOEXACT) != 0) {
+		rbtoptions |= DNS_RBTFIND_NOEXACT;
+	}
+
+	RWLOCK(&dbtable->tree_lock, isc_rwlocktype_read);
+
+	result = dns_rbt_findname(dbtable->rbt, name, rbtoptions, NULL,
+				  (void **)(void *)&stored_data);
+
+	if (result == ISC_R_SUCCESS || result == DNS_R_PARTIALMATCH) {
+		dns_db_attach(stored_data, dbp);
+	} else if (dbtable->default_db != NULL) {
+		dns_db_attach(dbtable->default_db, dbp);
+		result = DNS_R_PARTIALMATCH;
+	} else {
+		result = ISC_R_NOTFOUND;
+	}
+
+	RWUNLOCK(&dbtable->tree_lock, isc_rwlocktype_read);
+
+	return (result);
+}