Adding upstream version 2.7.6.upstream/2.7.6upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 947 insertions, 0 deletions

diff --git a/src/libknot/db/db.h b/src/libknot/db/db.h
new file mode 100644
index 0000000..f3edc15
--- /dev/null
+++ b/src/libknot/db/db.h
@@ -0,0 +1,91 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+/*!
+ * \file
+ *
+ * \brief Structures for binary data handling.
+ *
+ * \addtogroup db
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/mm_ctx.h"
+
+enum {
+	/* Database flags */
+
+	KNOT_DB_RDONLY = 1 << 0, /*!< Read only. */
+	KNOT_DB_SORTED = 1 << 1, /*!< Sorted output. */
+
+	/* Operations */
+
+	KNOT_DB_NOOP   = 1 << 2, /*!< No operation. */
+	KNOT_DB_FIRST  = 1 << 3, /*!< First entry. */
+	KNOT_DB_LAST   = 1 << 4, /*!< Last entry. */
+	KNOT_DB_NEXT   = 1 << 5, /*!< Next entry. */
+	KNOT_DB_PREV   = 1 << 6, /*!< Previous entry. */
+	KNOT_DB_LEQ    = 1 << 7, /*!< Lesser or equal. */
+	KNOT_DB_GEQ    = 1 << 8  /*!< Greater or equal. */
+};
+
+typedef void knot_db_t;
+typedef void knot_db_iter_t;
+
+typedef struct knot_db_val {
+	void *data;
+	size_t len;
+} knot_db_val_t;
+
+typedef struct knot_db_txn {
+	knot_db_t *db;
+	void *txn;
+} knot_db_txn_t;
+
+typedef struct knot_db_api {
+	const char *name;
+
+	/* Context operations */
+
+	int (*init)(knot_db_t **db, knot_mm_t *mm, void *opts);
+	void (*deinit)(knot_db_t *db);
+
+	/* Transactions */
+
+	int (*txn_begin)(knot_db_t *db, knot_db_txn_t *txn, unsigned flags);
+	int (*txn_commit)(knot_db_txn_t *txn);
+	void (*txn_abort)(knot_db_txn_t *txn);
+
+	/* Data access */
+
+	int (*count)(knot_db_txn_t *txn);
+	int (*clear)(knot_db_txn_t *txn);
+	int (*find)(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags);
+	int (*insert)(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags);
+	int (*del)(knot_db_txn_t *txn, knot_db_val_t *key);
+
+	/* Iteration */
+
+	knot_db_iter_t *(*iter_begin)(knot_db_txn_t *txn, unsigned flags);
+	knot_db_iter_t *(*iter_seek)(knot_db_iter_t *iter, knot_db_val_t *key, unsigned flags);
+	knot_db_iter_t *(*iter_next)(knot_db_iter_t *iter);
+	int (*iter_key)(knot_db_iter_t *iter, knot_db_val_t *key);
+	int (*iter_val)(knot_db_iter_t *iter, knot_db_val_t *val);
+	void (*iter_finish)(knot_db_iter_t *iter);
+} knot_db_api_t;
+
+/*! @} */
diff --git a/src/libknot/db/db_lmdb.c b/src/libknot/db/db_lmdb.c
new file mode 100644
index 0000000..f0e7be5
--- /dev/null
+++ b/src/libknot/db/db_lmdb.c
@@ -0,0 +1,568 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "libknot/attribute.h"
+#include "libknot/errcode.h"
+#include "libknot/db/db_lmdb.h"
+#include "contrib/mempattern.h"
+
+#include <lmdb.h>
+
+/* Defines */
+#define LMDB_DIR_MODE   0770
+#define LMDB_FILE_MODE  0660
+
+_public_ const unsigned KNOT_DB_LMDB_NOTLS = MDB_NOTLS;
+_public_ const unsigned KNOT_DB_LMDB_RDONLY = MDB_RDONLY;
+_public_ const unsigned KNOT_DB_LMDB_INTEGERKEY = MDB_INTEGERKEY;
+_public_ const unsigned KNOT_DB_LMDB_NOSYNC = MDB_NOSYNC;
+_public_ const unsigned KNOT_DB_LMDB_WRITEMAP = MDB_WRITEMAP;
+_public_ const unsigned KNOT_DB_LMDB_MAPASYNC = MDB_MAPASYNC;
+_public_ const unsigned KNOT_DB_LMDB_DUPSORT = MDB_DUPSORT;
+
+struct lmdb_env
+{
+	bool shared;
+	MDB_dbi dbi;
+	MDB_env *env;
+	knot_mm_t *pool;
+};
+
+/*!
+ * \brief Convert error code returned by LMDB to Knot DNS error code.
+ *
+ * LMDB defines own error codes but uses additional ones from libc:
+ * - LMDB errors do not conflict with Knot DNS ones.
+ * - Significant LMDB errors are mapped to Knot DNS ones.
+ * - Standard errors are converted to negative value to match Knot DNS mapping.
+ */
+static int lmdb_error_to_knot(int error)
+{
+	if (error == MDB_SUCCESS) {
+		return KNOT_EOK;
+	}
+
+	if (error == MDB_NOTFOUND) {
+		return KNOT_ENOENT;
+	}
+
+	if (error == MDB_TXN_FULL) {
+		return KNOT_ELIMIT;
+	}
+
+	if (error == MDB_MAP_FULL || error == ENOSPC) {
+		return KNOT_ESPACE;
+	}
+
+	return -abs(error);
+}
+
+static int create_env_dir(const char *path)
+{
+	int r = mkdir(path, LMDB_DIR_MODE);
+	if (r == -1 && errno != EEXIST) {
+		return lmdb_error_to_knot(errno);
+	}
+
+	return KNOT_EOK;
+}
+
+/*! \brief Set the environment map size.
+ * \note This also sets the maximum database size, see mdb_env_set_mapsize
+ */
+static int set_mapsize(MDB_env *env, size_t map_size)
+{
+	long page_size = sysconf(_SC_PAGESIZE);
+	if (page_size <= 0) {
+		return KNOT_ERROR;
+	}
+
+	/* Round to page size. */
+	map_size = (map_size / page_size) * page_size;
+	int ret = mdb_env_set_mapsize(env, map_size);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+/*! \brief Close the database. */
+static void dbase_close(struct lmdb_env *env)
+{
+	mdb_dbi_close(env->env, env->dbi);
+	if (!env->shared) {
+		mdb_env_close(env->env);
+	}
+}
+
+/*! \brief Open database environment. */
+static int dbase_open_env(struct lmdb_env *env, struct knot_db_lmdb_opts *opts)
+{
+	MDB_env *mdb_env = NULL;
+	int ret = mdb_env_create(&mdb_env);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	ret = create_env_dir(opts->path);
+	if (ret != KNOT_EOK) {
+		mdb_env_close(mdb_env);
+		return ret;
+	}
+
+	ret = set_mapsize(mdb_env, opts->mapsize);
+	if (ret != KNOT_EOK) {
+		mdb_env_close(mdb_env);
+		return ret;
+	}
+
+	ret = mdb_env_set_maxdbs(mdb_env, opts->maxdbs);
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(mdb_env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	ret = mdb_env_set_maxreaders(mdb_env, opts->maxreaders);
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(mdb_env);
+		return lmdb_error_to_knot(ret);
+	}
+
+#ifdef __OpenBSD__
+	/*
+	 * Enforce that MDB_WRITEMAP is set.
+	 *
+	 * MDB assumes a unified buffer cache.
+	 *
+	 * See http://www.openldap.org/pub/hyc/mdm-paper.pdf section 3.1,
+	 * references 17, 18, and 19.
+	 *
+	 * From Howard Chu: "This requirement can be relaxed in the
+	 * current version of the library. If you create the environment
+	 * with the MDB_WRITEMAP option then all reads and writes are
+	 * performed using mmap, so the file buffer cache is irrelevant.
+	 * Of course then you lose the protection that the read-only
+	 * map offers."
+	 */
+	opts->flags.env |= MDB_WRITEMAP;
+#endif
+
+	ret = mdb_env_open(mdb_env, opts->path, opts->flags.env, LMDB_FILE_MODE);
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(mdb_env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	/* Keep the environment pointer. */
+	env->env = mdb_env;
+
+	return KNOT_EOK;
+}
+
+static int dbase_open(struct lmdb_env *env, struct knot_db_lmdb_opts *opts)
+{
+	unsigned flags = 0;
+	if (opts->flags.env & KNOT_DB_LMDB_RDONLY) {
+		flags = MDB_RDONLY;
+	}
+
+	/* Open the database. */
+	MDB_txn *txn = NULL;
+	int ret = mdb_txn_begin(env->env, NULL, flags, &txn);
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(env->env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	ret = mdb_dbi_open(txn, opts->dbname, opts->flags.db | MDB_CREATE, &env->dbi);
+	if (ret != MDB_SUCCESS) {
+		mdb_txn_abort(txn);
+		mdb_env_close(env->env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	ret = mdb_txn_commit(txn);
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(env->env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static int init(knot_db_t **db_ptr, knot_mm_t *mm, void *arg)
+{
+	if (db_ptr == NULL || arg == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct lmdb_env *env = mm_alloc(mm, sizeof(struct lmdb_env));
+	if (env == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	memset(env, 0, sizeof(struct lmdb_env));
+	env->pool = mm;
+
+	/* Open new environment. */
+	struct lmdb_env *old_env = *db_ptr;
+	if (old_env == NULL) {
+		int ret = dbase_open_env(env, (struct knot_db_lmdb_opts *)arg);
+		if (ret != KNOT_EOK) {
+			mm_free(mm, env);
+			return ret;
+		}
+	} else {
+		/* Shared environment, this instance just owns the DBI. */
+		env->env = old_env->env;
+		env->shared = true;
+	}
+
+	/* Open the database. */
+	int ret = dbase_open(env, (struct knot_db_lmdb_opts *)arg);
+	if (ret != KNOT_EOK) {
+		mm_free(mm, env);
+		return ret;
+	}
+
+	/* Store the new environment. */
+	*db_ptr = env;
+
+	return KNOT_EOK;
+}
+
+static void deinit(knot_db_t *db)
+{
+	if (db) {
+		struct lmdb_env *env = db;
+
+		dbase_close(env);
+		mm_free(env->pool, env);
+	}
+}
+
+_public_
+int knot_db_lmdb_txn_begin(knot_db_t *db, knot_db_txn_t *txn, knot_db_txn_t *parent,
+                           unsigned flags)
+{
+	txn->db = db;
+	txn->txn = NULL;
+
+	unsigned txn_flags = 0;
+	if (flags & KNOT_DB_RDONLY) {
+		txn_flags |= MDB_RDONLY;
+	}
+
+	MDB_txn *parent_txn = (parent != NULL) ? (MDB_txn *)parent->txn : NULL;
+
+	struct lmdb_env *env = db;
+	int ret = mdb_txn_begin(env->env, parent_txn, txn_flags, (MDB_txn **)&txn->txn);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static int txn_begin(knot_db_t *db, knot_db_txn_t *txn, unsigned flags)
+{
+	return knot_db_lmdb_txn_begin(db, txn, NULL, flags);
+}
+
+static int txn_commit(knot_db_txn_t *txn)
+{
+	int ret = mdb_txn_commit((MDB_txn *)txn->txn);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static void txn_abort(knot_db_txn_t *txn)
+{
+	mdb_txn_abort((MDB_txn *)txn->txn);
+}
+
+static int count(knot_db_txn_t *txn)
+{
+	struct lmdb_env *env = txn->db;
+
+	MDB_stat stat;
+	int ret = mdb_stat(txn->txn, env->dbi, &stat);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return stat.ms_entries;
+}
+
+static int clear(knot_db_txn_t *txn)
+{
+	struct lmdb_env *env = txn->db;
+
+	int ret = mdb_drop(txn->txn, env->dbi, 0);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static knot_db_iter_t *iter_set(knot_db_iter_t *iter, knot_db_val_t *key, unsigned flags)
+{
+	MDB_cursor *cursor = iter;
+
+	MDB_cursor_op op = MDB_SET;
+	switch(flags) {
+	case KNOT_DB_NOOP:  return cursor;
+	case KNOT_DB_FIRST: op = MDB_FIRST; break;
+	case KNOT_DB_LAST:  op = MDB_LAST;  break;
+	case KNOT_DB_NEXT:  op = MDB_NEXT; break;
+	case KNOT_DB_PREV:  op = MDB_PREV; break;
+	case KNOT_DB_LEQ:
+	case KNOT_DB_GEQ:   op = MDB_SET_RANGE; break;
+	default: break;
+	}
+
+	MDB_val db_key = { 0, NULL };
+	if (key) {
+		db_key.mv_data = key->data;
+		db_key.mv_size = key->len;
+	}
+	MDB_val unused_key = { 0, NULL }, unused_val = { 0, NULL };
+
+	int ret = mdb_cursor_get(cursor, key ? &db_key : &unused_key, &unused_val, op);
+
+	/* LEQ is not supported in LMDB, workaround using GEQ. */
+	if (flags == KNOT_DB_LEQ && key) {
+		/* Searched key is after the last key. */
+		if (ret != MDB_SUCCESS) {
+			return iter_set(iter, NULL, KNOT_DB_LAST);
+		}
+		/* If the searched key != matched, get previous. */
+		if ((key->len != db_key.mv_size) ||
+		    (memcmp(key->data, db_key.mv_data, key->len) != 0)) {
+			return iter_set(iter, NULL, KNOT_DB_PREV);
+		}
+	}
+
+	if (ret != MDB_SUCCESS) {
+		mdb_cursor_close(cursor);
+		return NULL;
+	}
+
+	return cursor;
+}
+
+static knot_db_iter_t *iter_begin(knot_db_txn_t *txn, unsigned flags)
+{
+	struct lmdb_env *env = txn->db;
+	MDB_cursor *cursor = NULL;
+
+	int ret = mdb_cursor_open(txn->txn, env->dbi, &cursor);
+	if (ret != MDB_SUCCESS) {
+		return NULL;
+	}
+
+	/* Clear sorted flag, as it's always sorted. */
+	flags &= ~KNOT_DB_SORTED;
+
+	return iter_set(cursor, NULL, (flags == 0) ? KNOT_DB_FIRST : flags);
+}
+
+static knot_db_iter_t *iter_next(knot_db_iter_t *iter)
+{
+	return iter_set(iter, NULL, KNOT_DB_NEXT);
+}
+
+_public_
+int knot_db_lmdb_iter_del(knot_db_iter_t *iter)
+{
+	MDB_cursor *cursor = iter;
+
+	int ret = mdb_cursor_del(cursor, 0);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static int iter_key(knot_db_iter_t *iter, knot_db_val_t *key)
+{
+	MDB_cursor *cursor = iter;
+
+	MDB_val mdb_key, mdb_val;
+	int ret = mdb_cursor_get(cursor, &mdb_key, &mdb_val, MDB_GET_CURRENT);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	key->data = mdb_key.mv_data;
+	key->len  = mdb_key.mv_size;
+	return KNOT_EOK;
+}
+
+static int iter_val(knot_db_iter_t *iter, knot_db_val_t *val)
+{
+	MDB_cursor *cursor = iter;
+
+	MDB_val mdb_key, mdb_val;
+	int ret = mdb_cursor_get(cursor, &mdb_key, &mdb_val, MDB_GET_CURRENT);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	val->data = mdb_val.mv_data;
+	val->len  = mdb_val.mv_size;
+	return KNOT_EOK;
+}
+
+static void iter_finish(knot_db_iter_t *iter)
+{
+	if (iter == NULL) {
+		return;
+	}
+
+	MDB_cursor *cursor = iter;
+	mdb_cursor_close(cursor);
+}
+
+static int find(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags)
+{
+	knot_db_iter_t *iter = iter_begin(txn, KNOT_DB_NOOP);
+	if (iter == NULL) {
+		return KNOT_ERROR;
+	}
+
+	int ret = KNOT_EOK;
+	if (iter_set(iter, key, flags) == NULL) {
+		return KNOT_ENOENT;
+	} else {
+		ret = iter_val(iter, val);
+	}
+
+	iter_finish(iter);
+	return ret;
+}
+
+static int insert(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags)
+{
+	struct lmdb_env *env = txn->db;
+
+	MDB_val db_key = { key->len, key->data };
+	MDB_val data = { val->len, val->data };
+
+	/* Reserve if only size is declared. */
+	unsigned mdb_flags = 0;
+	if (val->len > 0 && val->data == NULL) {
+		mdb_flags |= MDB_RESERVE;
+	}
+
+	int ret = mdb_put(txn->txn, env->dbi, &db_key, &data, mdb_flags);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	/* Update the result. */
+	val->data = data.mv_data;
+	val->len = data.mv_size;
+
+	return KNOT_EOK;
+}
+
+static int del(knot_db_txn_t *txn, knot_db_val_t *key)
+{
+	struct lmdb_env *env = txn->db;
+	MDB_val db_key = { key->len, key->data };
+	MDB_val data = { 0, NULL };
+
+	int ret = mdb_del(txn->txn, env->dbi, &db_key, &data);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_db_lmdb_del_exact(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val)
+{
+	struct lmdb_env *env = txn->db;
+	MDB_val db_key = { key->len, key->data };
+	MDB_val data = { val->len, val->data };
+
+	int ret = mdb_del(txn->txn, env->dbi, &db_key, &data);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+size_t knot_db_lmdb_get_mapsize(knot_db_t *db)
+{
+	struct lmdb_env *env = db;
+	MDB_envinfo info;
+	if (mdb_env_info(env->env, &info) != MDB_SUCCESS) {
+		return 0;
+	}
+
+	return info.me_mapsize;
+}
+
+// you should SUM all the usages of DBs sharing one mapsize
+_public_
+size_t knot_db_lmdb_get_usage(knot_db_t *db)
+{
+	struct lmdb_env *env = db;
+	knot_db_txn_t txn;
+	knot_db_lmdb_txn_begin(db, &txn, NULL, KNOT_DB_RDONLY);
+	MDB_stat st;
+	if (mdb_stat(txn.txn, env->dbi, &st) != MDB_SUCCESS) {
+		txn_abort(&txn);
+		return 0;
+	}
+	txn_abort(&txn);
+
+	size_t pgs_used = st.ms_branch_pages + st.ms_leaf_pages + st.ms_overflow_pages;
+
+	return (pgs_used * st.ms_psize);
+}
+
+_public_
+const knot_db_api_t *knot_db_lmdb_api(void)
+{
+	static const knot_db_api_t api = {
+		"lmdb",
+		init, deinit,
+		txn_begin, txn_commit, txn_abort,
+		count, clear, find, insert, del,
+		iter_begin, iter_set, iter_next, iter_key, iter_val, iter_finish
+	};
+
+	return &api;
+}
diff --git a/src/libknot/db/db_lmdb.h b/src/libknot/db/db_lmdb.h
new file mode 100644
index 0000000..d0213cf
--- /dev/null
+++ b/src/libknot/db/db_lmdb.h
@@ -0,0 +1,71 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+/*!
+ * \file
+ *
+ * \addtogroup db
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/db/db.h"
+
+/* Defines. */
+#define KNOT_DB_LMDB_MAPSIZE    (100 * 1024 * 1024)
+
+/* LMDB specific flags. */
+extern const unsigned KNOT_DB_LMDB_NOTLS;
+extern const unsigned KNOT_DB_LMDB_RDONLY;
+extern const unsigned KNOT_DB_LMDB_INTEGERKEY;
+extern const unsigned KNOT_DB_LMDB_NOSYNC;
+extern const unsigned KNOT_DB_LMDB_WRITEMAP;
+extern const unsigned KNOT_DB_LMDB_MAPASYNC;
+extern const unsigned KNOT_DB_LMDB_DUPSORT;
+
+/* Native options. */
+struct knot_db_lmdb_opts {
+	const char *path;     /*!< Database environment path. */
+	const char *dbname;   /*!< Database name (or NULL). */
+	size_t mapsize;       /*!< Environment map size. */
+	unsigned maxdbs;      /*!< Maximum number of databases in the env. */
+	unsigned maxreaders;  /*!< Maximum number of concurrent readers */
+	struct {
+		unsigned env; /*!< Environment flags. */
+		unsigned db;  /*!< Database flags. */
+	} flags;
+};
+
+/* Default options. */
+#define KNOT_DB_LMDB_OPTS_INITIALIZER { \
+	NULL, NULL, \
+	KNOT_DB_LMDB_MAPSIZE, \
+	0, \
+	126, /* = contrib/lmdb/mdb.c DEFAULT_READERS */ \
+	{ 0, 0 } \
+}
+
+const knot_db_api_t *knot_db_lmdb_api(void);
+
+/* LMDB specific operations. */
+int knot_db_lmdb_del_exact(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val);
+int knot_db_lmdb_txn_begin(knot_db_t *db, knot_db_txn_t *txn, knot_db_txn_t *parent,
+                           unsigned flags);
+int knot_db_lmdb_iter_del(knot_db_iter_t *iter);
+size_t knot_db_lmdb_get_mapsize(knot_db_t *db);
+size_t knot_db_lmdb_get_usage(knot_db_t *db);
+
+/*! @} */
diff --git a/src/libknot/db/db_trie.c b/src/libknot/db/db_trie.c
new file mode 100644
index 0000000..d0fbb0c
--- /dev/null
+++ b/src/libknot/db/db_trie.c
@@ -0,0 +1,178 @@
+/*  Copyright (C) 2016 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <assert.h>
+
+#include "libknot/attribute.h"
+#include "libknot/errcode.h"
+#include "libknot/db/db_trie.h"
+#include "contrib/qp-trie/trie.h"
+#include "contrib/macros.h"
+#include "contrib/mempattern.h"
+
+static int init(knot_db_t **db, knot_mm_t *mm, void *arg)
+{
+	if (db == NULL || arg == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct knot_db_trie_opts *opts = arg;
+	UNUSED(opts);
+	trie_t *trie = trie_create(mm);
+	if (!trie) {
+		return KNOT_ENOMEM;
+	}
+
+	*db = trie;
+
+	return KNOT_EOK;
+}
+
+static void deinit(knot_db_t *db)
+{
+	trie_free((trie_t *)db);
+}
+
+static int txn_begin(knot_db_t *db, knot_db_txn_t *txn, unsigned flags)
+{
+	txn->txn = (void *)(size_t)flags;
+	txn->db  = db;
+	return KNOT_EOK; /* N/A */
+}
+
+static int txn_commit(knot_db_txn_t *txn)
+{
+	return KNOT_EOK;
+}
+
+static void txn_abort(knot_db_txn_t *txn)
+{
+}
+
+static int count(knot_db_txn_t *txn)
+{
+	return trie_weight((trie_t *)txn->db);
+}
+
+static int clear(knot_db_txn_t *txn)
+{
+	trie_clear((trie_t *)txn->db);
+
+	return KNOT_EOK;
+}
+
+static int find(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags)
+{
+	trie_val_t *ret = trie_get_try((trie_t *)txn->db, key->data, key->len);
+	if (ret == NULL) {
+		return KNOT_ENOENT;
+	}
+
+	val->data = *ret;
+	val->len  = sizeof(trie_val_t); /* Trie doesn't support storing length. */
+	return KNOT_EOK;
+}
+
+static int insert(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags)
+{
+	/* No flags supported. */
+	if (flags != 0) {
+		return KNOT_ENOTSUP;
+	}
+
+	trie_val_t *ret = trie_get_ins((trie_t *)txn->db, key->data, key->len);
+	if (ret == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	*ret = val->data;
+	return KNOT_EOK;
+}
+
+static int del(knot_db_txn_t *txn, knot_db_val_t *key)
+{
+	return trie_del((trie_t *)txn->db, key->data, key->len, NULL);
+}
+
+static knot_db_iter_t *iter_begin(knot_db_txn_t *txn, unsigned flags)
+{
+	flags &= ~KNOT_DB_SORTED;
+
+	/* No operations other than begin are supported right now. */
+	if (flags != 0) {
+		return NULL;
+	}
+
+	return trie_it_begin((trie_t *)txn->db);
+}
+
+static knot_db_iter_t *iter_seek(knot_db_iter_t *iter, knot_db_val_t *key, unsigned flags)
+{
+	assert(0);
+	return NULL; /* ENOTSUP */
+}
+
+static knot_db_iter_t *iter_next(knot_db_iter_t *iter)
+{
+	trie_it_next((trie_it_t *)iter);
+	if (trie_it_finished((trie_it_t *)iter)) {
+		trie_it_free((trie_it_t *)iter);
+		return NULL;
+	}
+
+	return iter;
+}
+
+static int iter_key(knot_db_iter_t *iter, knot_db_val_t *val)
+{
+	val->data = (void *)trie_it_key((trie_it_t *)iter, &val->len);
+	if (val->data == NULL) {
+		return KNOT_ENOENT;
+	}
+
+	return KNOT_EOK;
+}
+
+static int iter_val(knot_db_iter_t *iter, knot_db_val_t *val)
+{
+	trie_val_t *ret = trie_it_val((trie_it_t *)iter);
+	if (ret == NULL) {
+		return KNOT_ENOENT;
+	}
+
+	val->data = *ret;
+	val->len  = sizeof(trie_val_t);
+	return KNOT_EOK;
+}
+
+static void iter_finish(knot_db_iter_t *iter)
+{
+	trie_it_free((trie_it_t *)iter);
+}
+
+_public_
+const knot_db_api_t *knot_db_trie_api(void)
+{
+	static const knot_db_api_t api = {
+		"trie",
+		init, deinit,
+		txn_begin, txn_commit, txn_abort,
+		count, clear, find, insert, del,
+		iter_begin, iter_seek, iter_next, iter_key, iter_val, iter_finish
+	};
+
+	return &api;
+}
diff --git a/src/libknot/db/db_trie.h b/src/libknot/db/db_trie.h
new file mode 100644
index 0000000..d2afdf8
--- /dev/null
+++ b/src/libknot/db/db_trie.h
@@ -0,0 +1,39 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+/*!
+ * \file
+ *
+ * \addtogroup db
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/db/db.h"
+
+/* Native options. */
+struct knot_db_trie_opts {
+	unsigned unused;
+};
+
+/* Default options. */
+#define KNOT_DB_TRIE_OPTS_INITIALIZER { \
+	0 \
+}
+
+const knot_db_api_t *knot_db_trie_api(void);
+
+/*! @} */