dlz/drivers/dlz_bdb_driver.c

	dlz_bdb_driver.c revision 793814f80703afdd69b59ade91e63efa81ae4178
/*
 * Copyright (C) 2002 Stichting NLnet, Netherlands, stichting@nlnet.nl.
 *
 * Permission to use, copy, modify, and 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 STICHTING NLNET
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * STICHTING NLNET 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.
 *
 * The development of Dynamically Loadable Zones (DLZ) for Bind 9 was
 * conceived and contributed by Rob Butler.
 *
 * Permission to use, copy, modify, and 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 ROB BUTLER
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * ROB BUTLER 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.
 */

/*
 * Copyright (C) 1999-2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and 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 INTERNET SOFTWARE CONSORTIUM
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * INTERNET SOFTWARE CONSORTIUM 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.
 */

#ifdef DLZ_BDB

#include <config.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <dns/log.h>
#include <dns/sdlz.h>
#include <dns/result.h>

#include <isc/mem.h>
#include <isc/print.h>
#include <isc/result.h>
#include <isc/util.h>

#include <named/globals.h>

#include <dlz/dlz_bdb_driver.h>

#include <db.h>

static dns_sdlzimplementation_t *dlz_bdb = NULL;

/* should the bdb driver use threads. */
#ifdef ISC_PLATFORM_USETHREADS
#define bdb_threads DB_THREAD
#else
#define bdb_threads 0
#endif

/* BDB database names */
#define dlz_data "dns_data"
#define dlz_zone "dns_zone"
#define dlz_host "dns_host"
#define dlz_client "dns_client"

/*%
 * This structure contains all the Berkeley DB handles
 * for this instance of the BDB driver.
 */

typedef struct bdb_instance {
    DB_ENV  *dbenv;     /*%< BDB environment */
    DB  *data;      /*%< dns_data database handle */
    DB  *zone;      /*%< zone database handle */
    DB  *host;      /*%< host database handle */
    DB  *client;    /*%< client database handle */
    isc_mem_t *mctx;    /*%< memory context */

} bdb_instance_t;

typedef struct parsed_data {
    char *zone;
    char *host;
    char *type;
    int ttl;
    char *data;
} parsed_data_t;


/* forward reference */

static isc_result_t
bdb_findzone(void *driverarg, void *dbdata, const char *name);

/*%
 * Parses the DBT from the Berkeley DB into a parsed_data record
 * The parsed_data record should be allocated before and passed into the
 * bdb_parse_data function.  The char (type & data) fields should not
 * be "free"d as that memory is part of the DBT data field.  It will be
 * "free"d when the DBT is freed.
 */

static isc_result_t
bdb_parse_data(char *in, parsed_data_t *pd) {

    char *endp, *ttlStr;
    char *tmp = in;
    char *lastchar = (char *) &tmp[strlen(tmp) + 1];

    /*%
     * String should be formated as:
     * zone(a space)host(a space)ttl(a space)type(a space)remaining data
     * examples:
     * example.com www 10 A 127.0.0.1
     * example.com mail 10 A 127.0.0.2
     * example.com @ 10 MX 20 mail.example.com
     */

    /* save pointer to zone */
    pd->zone = tmp;

    /* find space after zone and change it to a '\0' */
    tmp = strchr(tmp, ' ');
    /* verify we found a space */
    if (tmp == NULL)
        return ISC_R_FAILURE;
    /* change the space to a null (string terminator) */
    tmp[0] = '\0';
    /* make sure it is safe to increment pointer */
    if (++tmp > lastchar)
        return ISC_R_FAILURE;

    /* save pointer to host */
    pd->host = tmp;

    /* find space after type and change it to a '\0' */
    tmp = strchr(tmp, ' ');
    /* verify we found a space */
    if (tmp == NULL)
        return ISC_R_FAILURE;
    /* change the space to a null (string terminator) */
    tmp[0] = '\0';
    /* make sure it is safe to increment pointer */
    if (++tmp > lastchar)
        return ISC_R_FAILURE;

    /* save pointer to dns type */
    pd->type = tmp;

    /* find space after type and change it to a '\0' */
    tmp = strchr(tmp, ' ');
    /* verify we found a space */
    if (tmp == NULL)
        return ISC_R_FAILURE;
    /* change the space to a null (string terminator) */
    tmp[0] = '\0';
    /* make sure it is safe to increment pointer */
    if (++tmp > lastchar)
        return ISC_R_FAILURE;

    /* save pointer to dns ttl */
    ttlStr = tmp;

    /* find space after ttl and change it to a '\0' */
    tmp = strchr(tmp, ' ');
    /* verify we found a space */
    if (tmp == NULL)
        return ISC_R_FAILURE;
    /* change the space to a null (string terminator) */
    tmp[0] = '\0';
    /* make sure it is safe to increment pointer */
    if (++tmp > lastchar)
        return ISC_R_FAILURE;

    /* save pointer to remainder of DNS data */
    pd->data = tmp;

    /* convert ttl string to integer */
    pd->ttl = strtol(ttlStr, &endp, 10);
    if (*endp != '\0' || pd->ttl < 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "BDB driver ttl must be a postive number");
        return ISC_R_FAILURE;
    }

    /* if we get this far everything should have worked. */
    return ISC_R_SUCCESS;
}

/*
 * DLZ methods
 */

static isc_result_t
bdb_allowzonexfr(void *driverarg, void *dbdata, const char *name,
         const char *client)
{
    isc_result_t result;
    bdb_instance_t *db = (bdb_instance_t *) dbdata;
    DBC *client_cursor = NULL;
    DBT key, data;

    /* check to see if we are authoritative for the zone first. */
    result = bdb_findzone(driverarg, dbdata, name);
    if (result != ISC_R_SUCCESS)
        return (ISC_R_NOTFOUND);

    memset(&key, 0, sizeof(DBT));
    key.flags = DB_DBT_MALLOC;
    key.data = strdup(name);
    if (key.data == NULL) {
        result = ISC_R_NOMEMORY;
        goto xfr_cleanup;
    }
    key.size = strlen(key.data);

    memset(&data, 0, sizeof(DBT));
    data.flags = DB_DBT_MALLOC;
    data.data = strdup(client);
    if (data.data == NULL) {
        result = ISC_R_NOMEMORY;
        goto xfr_cleanup;
    }
    data.size = strlen(data.data);

    /* get a cursor to loop through zone data */
    if (db->client->cursor(db->client, NULL, &client_cursor, 0) != 0) {
        result = ISC_R_FAILURE;
        goto xfr_cleanup;
    }

    switch(client_cursor->c_get(client_cursor, &key, &data, DB_GET_BOTH)) {
    case DB_NOTFOUND:
    case DB_SECONDARY_BAD:
        result = ISC_R_NOTFOUND;
        break;
    case 0:
        result = ISC_R_SUCCESS;
        break;
    default:
        result = ISC_R_FAILURE;
    }

 xfr_cleanup:

    /* free any memory duplicate string in the key field */
    if (key.data != NULL)
        free(key.data);

    /* free any memory allocated to the data field. */
    if (data.data != NULL)
        free(data.data);

    /* get rid of zone_cursor */
    if (client_cursor != NULL)
        client_cursor->c_close(client_cursor);

    return result;

}

static isc_result_t
bdb_allnodes(const char *zone, void *driverarg, void *dbdata,
         dns_sdlzallnodes_t *allnodes)
{

    isc_result_t result = ISC_R_NOTFOUND;
    bdb_instance_t *db = (bdb_instance_t *) dbdata;
    DBC *zone_cursor = NULL;
    DBT key, data;
    int flags;
    int bdbres;
    parsed_data_t pd;
    char *tmp = NULL, *tmp_zone;

    UNUSED(driverarg);

    memset(&key, 0, sizeof(DBT));
    memset(&data, 0, sizeof(DBT));

    key.data = tmp_zone = strdup(zone);

    if (key.data == NULL)
        return (ISC_R_NOMEMORY);

    key.size = strlen(key.data);

    /* get a cursor to loop through zone data */
    if (db->zone->cursor(db->zone, NULL, &zone_cursor, 0) != 0) {
        result = ISC_R_FAILURE;
        goto allnodes_cleanup;
    }

    flags = DB_SET;

    while ((bdbres = zone_cursor->c_get(zone_cursor, &key, &data,
                        flags)) == 0) {

        flags = DB_NEXT_DUP;

        tmp = realloc(tmp, data.size + 1);
        if (tmp == NULL)
            goto allnodes_cleanup;

        strncpy(tmp, data.data, data.size);
        tmp[data.size] = '\0';

        if (bdb_parse_data(tmp, &pd) != ISC_R_SUCCESS)
            goto allnodes_cleanup;

        result = dns_sdlz_putnamedrr(allnodes, pd.host, pd.type,
                         pd.ttl, pd.data);
        if (result != ISC_R_SUCCESS)
            goto allnodes_cleanup;

    } /* end while loop */

 allnodes_cleanup:

    if (tmp != NULL)
        free(tmp);

    /* free any memory duplicate string in the key field */
    if (tmp_zone != NULL)
        free(tmp_zone);

    /* get rid of zone_cursor */
    if (zone_cursor != NULL)
        zone_cursor->c_close(zone_cursor);

    return result;

}

/*%
 * Performs BDB cleanup.
 * Used by bdb_create if there is an error starting up.
 * Used by bdb_destroy when the driver is shutting down.
 */

static void
bdb_cleanup(bdb_instance_t *db) {

    isc_mem_t *mctx;

    /* close databases */
    if (db->data != NULL)
        db->data->close(db->data, 0);
    if (db->host != NULL)
        db->host->close(db->host, 0);
    if (db->zone != NULL)
        db->zone->close(db->zone, 0);
    if (db->client != NULL)
        db->client->close(db->client, 0);

    /* close environment */
    if (db->dbenv != NULL)
        db->dbenv->close(db->dbenv, 0);

    /* cleanup memory */
    if (db->mctx != NULL) {
        /* save mctx for later */
        mctx = db->mctx;
        /* return, and detach the memory */
        isc_mem_put(mctx, db, sizeof(bdb_instance_t));
        isc_mem_detach(&mctx);
    }
}

static isc_result_t
bdb_findzone(void *driverarg, void *dbdata, const char *name)
{

    isc_result_t result;
    bdb_instance_t *db = (bdb_instance_t *) dbdata;
    DBC *zone_cursor = NULL;
    DBT key, data;

    UNUSED(driverarg);

    memset(&key, 0, sizeof(DBT));
    memset(&data, 0, sizeof(DBT));
    data.flags = DB_DBT_MALLOC;

    key.data = strdup(name);

    if (key.data == NULL)
        return (ISC_R_NOMEMORY);

    key.size = strlen(key.data);

    /* get a cursor to loop through zone data */
    if (db->zone->cursor(db->zone, NULL, &zone_cursor, 0) != 0) {
        result = ISC_R_NOTFOUND;
        goto findzone_cleanup;
    }

    switch(zone_cursor->c_get(zone_cursor, &key, &data, DB_SET)) {
    case DB_NOTFOUND:
    case DB_SECONDARY_BAD:
        result = ISC_R_NOTFOUND;
        break;
    case 0:
        result = ISC_R_SUCCESS;
        break;
    default:
        result = ISC_R_FAILURE;
    }

 findzone_cleanup:

    /* free any memory duplicate string in the key field */
    if (key.data != NULL)
        free(key.data);

    /* free any memory allocated to the data field. */
    if (data.data != NULL)
        free(data.data);

    /* get rid of zone_cursor */
    if (zone_cursor != NULL)
        zone_cursor->c_close(zone_cursor);

    return result;
}

static isc_result_t
bdb_lookup(const char *zone, const char *name, void *driverarg,
       void *dbdata, dns_sdlzlookup_t *lookup,
       dns_clientinfomethods_t *methods, dns_clientinfo_t *clientinfo)
{

    isc_result_t result = ISC_R_NOTFOUND;
    bdb_instance_t *db = (bdb_instance_t *) dbdata;
    DBC *zone_cursor = NULL;
    DBC *host_cursor = NULL;
    DBC *join_cursor = NULL;
    DBT key, data;
    DBC *cur_arr[3];
    int bdbres;
    parsed_data_t pd;
    char *tmp_zone, *tmp_host = NULL;
    char *tmp = NULL;

    UNUSED(driverarg);
    UNUSED(methods);
    UNUSED(clientinfo);

    memset(&key, 0, sizeof(DBT));
    memset(&data, 0, sizeof(DBT));

    /* set zone key */
    key.data = tmp_zone = strdup(zone);
    if (key.data == NULL) {
        result = ISC_R_NOMEMORY;
        goto lookup_cleanup;
    }
    key.size = strlen(key.data);

    /* get a cursor to loop through zone data */
    if (db->zone->cursor(db->zone, NULL, &zone_cursor, 0) != 0) {
        result = ISC_R_FAILURE;
        goto lookup_cleanup;
    }

    /* initialize zone_cursor with zone_key */
    if (zone_cursor->c_get(zone_cursor, &key, &data, DB_SET) != 0) {
        result = ISC_R_NOTFOUND;
        goto lookup_cleanup;
    }

    /* set host key */
    key.data = tmp_host = strdup(name);
    if (key.data == NULL) {
        result = ISC_R_NOMEMORY;
        goto lookup_cleanup;
    }
    key.size = strlen(key.data);

    /* get a cursor to loop through host data */
    if (db->host->cursor(db->host, NULL, &host_cursor, 0) != 0) {
        result = ISC_R_FAILURE;
        goto lookup_cleanup;
    }

    /* initialize host_cursor with host_key */
    if (host_cursor->c_get(host_cursor, &key, &data, DB_SET) != 0) {
        result = ISC_R_NOTFOUND;
        goto lookup_cleanup;
    }

    cur_arr[0] = zone_cursor;
    cur_arr[1] = host_cursor;
    cur_arr[2] = NULL;

    db->data->join(db->data, cur_arr, &join_cursor, 0);

    while ((bdbres = join_cursor->c_get(join_cursor, &key,
                        &data, 0)) == 0) {

        tmp = realloc(tmp, data.size + 1);
        if (tmp == NULL)
            goto lookup_cleanup;

        strncpy(tmp, data.data, data.size);
        tmp[data.size] = '\0';

        if (bdb_parse_data(tmp, &pd) != ISC_R_SUCCESS)
            goto lookup_cleanup;

        result = dns_sdlz_putrr(lookup, pd.type, pd.ttl, pd.data);

        if (result != ISC_R_SUCCESS)
            goto lookup_cleanup;
    } /* end while loop */

 lookup_cleanup:

    if (tmp != NULL)
        free(tmp);
    if (tmp_zone != NULL)
        free(tmp_zone);
    if (tmp_host != NULL)
        free(tmp_host);

    /* get rid of the joined cusor */
    if (join_cursor != NULL)
        join_cursor->c_close(join_cursor);

    /* get rid of zone_cursor */
    if (zone_cursor != NULL)
        zone_cursor->c_close(zone_cursor);

    /* get rid of host_cursor */
    if (host_cursor != NULL)
        host_cursor->c_close(host_cursor);

    return result;
}


/*% Initializes, sets flags and then opens Berkeley databases. */

static isc_result_t
bdb_opendb(DB_ENV *db_env, DBTYPE db_type, DB **db, const char *db_name,
       char *db_file, int flags) {

    int result;

    /* Initialize the database. */
    if ((result = db_create(db, db_env, 0)) != 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "BDB could not initialize %s database. "
                  "BDB error: %s",
                  db_name, db_strerror(result));
        return ISC_R_FAILURE;
    }

    /* set database flags. */
    if ((result = (*db)->set_flags(*db, flags)) != 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "BDB could not set flags for %s database. "
                  "BDB error: %s",
                  db_name, db_strerror(result));
        return ISC_R_FAILURE;
    }

    /* open the database. */
    if ((result = (*db)->open(*db, NULL, db_file, db_name, db_type,
                  DB_RDONLY | bdb_threads, 0)) != 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "BDB could not open %s database in %s. "
                  "BDB error: %s",
                  db_name, db_file, db_strerror(result));
        return ISC_R_FAILURE;
    }

    return ISC_R_SUCCESS;
}

static isc_result_t
bdb_create(const char *dlzname, unsigned int argc, char *argv[],
       void *driverarg, void **dbdata)
{
    isc_result_t result;
    int bdbres;
    bdb_instance_t *db = NULL;

    UNUSED(dlzname);
    UNUSED(driverarg);

    /* verify we have 3 arg's passed to the driver */
    if (argc != 3) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "Berkeley DB driver requires at least "
                  "2 command line args.");
        return (ISC_R_FAILURE);
    }

    /* allocate and zero memory for driver structure */
    db = isc_mem_get(ns_g_mctx, sizeof(bdb_instance_t));
    if (db == NULL) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "Could not allocate memory for "
                  "database instance object.");
        return (ISC_R_NOMEMORY);
    }
    memset(db, 0, sizeof(bdb_instance_t));

    /* attach to the memory context */
    isc_mem_attach(ns_g_mctx, &db->mctx);

    /* create BDB environment
     * Basically BDB allocates and assigns memory to db->dbenv
     */
    bdbres = db_env_create(&db->dbenv, 0);
    if (bdbres != 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "BDB environment could not be created. "
                  "BDB error: %s",
                  db_strerror(bdbres));
        result = ISC_R_FAILURE;
        goto init_cleanup;
    }

    /* open BDB environment */
    bdbres = db->dbenv->open(db->dbenv, argv[1],
                 DB_INIT_CDB | DB_INIT_MPOOL |
                 bdb_threads | DB_CREATE,
                 0);
    if (bdbres != 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "BDB environment at '%s' could not be opened. "
                  "BDB error: %s",
                  argv[1], db_strerror(bdbres));
        result = ISC_R_FAILURE;
        goto init_cleanup;
    }

    /* open dlz_data database. */
    result = bdb_opendb(db->dbenv, DB_UNKNOWN, &db->data,
                dlz_data, argv[2], 0);
    if (result != ISC_R_SUCCESS)
        goto init_cleanup;

    /* open dlz_host database. */
    result = bdb_opendb(db->dbenv, DB_UNKNOWN, &db->host,
                dlz_host, argv[2],
                DB_DUP | DB_DUPSORT);
    if (result != ISC_R_SUCCESS)
        goto init_cleanup;

    /* open dlz_zone database. */
    result = bdb_opendb(db->dbenv, DB_UNKNOWN, &db->zone,
                dlz_zone, argv[2],
                DB_DUP | DB_DUPSORT);
    if (result != ISC_R_SUCCESS)
        goto init_cleanup;

    /* open dlz_client database. */
    result = bdb_opendb(db->dbenv, DB_UNKNOWN, &db->client,
                dlz_client, argv[2], DB_DUP | DB_DUPSORT);
    if (result != ISC_R_SUCCESS)
        goto init_cleanup;

    /* associate the host secondary database with the primary database */
    bdbres = db->data->associate(db->data, NULL, db->host, NULL, 0);
    if (bdbres != 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "BDB could not associate %s database with %s. "
                  "BDB error: %s",
                  dlz_host, dlz_data, db_strerror(bdbres));
        result = ISC_R_FAILURE;
        goto init_cleanup;
    }

    /* associate the zone secondary database with the primary database */
    bdbres = db->data->associate(db->data, NULL, db->zone, NULL, 0);
    if (bdbres != 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "BDB could not associate %s database with %s. "
                  "BDB error: %s",
                  dlz_zone, dlz_data, db_strerror(bdbres));
        result = ISC_R_FAILURE;
        goto init_cleanup;
    }

    *dbdata = db;

    return(ISC_R_SUCCESS);

 init_cleanup:

    bdb_cleanup(db);
    return result;
}

static void
bdb_destroy(void *driverarg, void *dbdata)
{
    UNUSED(driverarg);

    bdb_cleanup((bdb_instance_t *) dbdata);
}

/* bdb_authority not needed as authority data is returned by lookup */
static dns_sdlzmethods_t dlz_bdb_methods = {
    bdb_create,
    bdb_destroy,
    bdb_findzone,
    bdb_lookup,
    NULL,
    bdb_allnodes,
    bdb_allowzonexfr,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
};

/*%
 * Wrapper around dns_sdlzregister().
 */
isc_result_t
dlz_bdb_init(void) {
    isc_result_t result;

    /*
     * Write debugging message to log
     */
    isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
              DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(2),
              "Registering DLZ bdb driver.");

    result = dns_sdlzregister("bdb", &dlz_bdb_methods, NULL,
                  DNS_SDLZFLAG_RELATIVEOWNER |
                  DNS_SDLZFLAG_RELATIVERDATA |
                  DNS_SDLZFLAG_THREADSAFE,
                  ns_g_mctx, &dlz_bdb);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "dns_sdlzregister() failed: %s",
                 isc_result_totext(result));
        result = ISC_R_UNEXPECTED;
    }


    return result;
}

/*%
 * Wrapper around dns_sdlzunregister().
 */
void
dlz_bdb_clear(void) {

    /*
     * Write debugging message to log
     */
    isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
              DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(2),
              "Unregistering DLZ bdb driver.");

    if (dlz_bdb != NULL)
        dns_sdlzunregister(&dlz_bdb);
}

#endif