modules/bdbhpt/dlz_bdbhpt_dynamic.c

/*
 * 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) 2011  Internet Systems Consortium, Inc. ("ISC")
 *
 * 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.
 */

/*
 * This is simply a merge of Andrew Tridgell's dlz_example.c and the
 * original bdb_bdbhpt_driver.c
 *
 * This provides the externally loadable bdbhpt DLZ driver, without
 * update support
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <stdint.h>

#include <db.h>

#include "dlz_minimal.h"

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

/* bdbhpt database names */
#define dlz_data   "dns_data"
#define dlz_zone   "dns_zone"
#define dlz_xfr    "dns_xfr"
#define dlz_client "dns_client"

#define dlz_bdbhpt_dynamic_version "0.1"

/*
 * This structure contains all our DB handles and helper functions we
 * inherit from the dlz_dlopen driver
 *
 */
typedef struct bdbhpt_instance {
    DB_ENV    *dbenv;       /* bdbhpt environment */
    DB        *data;        /* dns_data database handle */
    DB        *zone;        /* zone database handle */
    DB        *xfr;         /* zone xfr database handle */
    DB        *client;      /* client database handle */

    /* Helper functions from the dlz_dlopen driver */
    log_t *log;
    dns_sdlz_putrr_t *putrr;
    dns_sdlz_putnamedrr_t *putnamedrr;
    dns_dlz_writeablezone_t *writeable_zone;
} bdbhpt_instance_t;

typedef struct bdbhpt_parsed_data {
    char *host;
    char *type;
    int ttl;
    char *data;
} bdbhpt_parsed_data_t;

static void
b9_add_helper(struct bdbhpt_instance *db, const char *helper_name, void *ptr);

/*%
 * Reverses a string in place.
 */
static char
*bdbhpt_strrev(char *str) {
    char *p1, *p2;

    if (! str || ! *str)
        return str;
    for (p1 = str, p2 = str + strlen(str) - 1; p2 > p1; ++p1, --p2) {
        *p1 ^= *p2;
        *p2 ^= *p1;
        *p1 ^= *p2;
    }
    return str;
}

/*%
 * Parses the DBT from the Berkeley DB into a parsed_data record
 * The parsed_data record should be allocated before and passed into the
 * bdbhpt_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
bdbhpt_parse_data(log_t *log, char *in, bdbhpt_parsed_data_t *pd) {

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

    /*%
     * String should be formatted as:
     *   replication_id
     *   (a space)
     *   host_name
     *   (a space)
     *   ttl
     *   (a space)
     *   type
     *   (a space)
     *   remaining data
     *
     * examples:
     *
     * 9191 host 10 A 127.0.0.1
     * server1_212 host 10 A 127.0.0.2
     * {xxxx-xxxx-xxxx-xxxx-xxxx} host 10 MX 20 mail.example.com
     */

    /*
     * we don't need the replication id, so don't
     * bother saving a pointer to it.
     */

    /* find space after replication id */
    tmp = strchr(tmp, ' ');
    /* verify we found a space */
    if (tmp == NULL)
        return ISC_R_FAILURE;
    /* 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 host 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 ttl string */
    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 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 remainder of DNS data */
    pd->data = tmp;

    /* convert ttl string to integer */
    pd->ttl = strtol(ttlStr, &endp, 10);
    if (*endp != '\0' || pd->ttl < 0) {
        log(ISC_LOG_ERROR,
                "bdbhpt_dynamic: "
                "ttl must be a positive number");
        return ISC_R_FAILURE;
    }

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

/*
 * See if a zone transfer is allowed
 */
isc_result_t
dlz_allowzonexfr(void *dbdata, const char *name, const char *client) {
    isc_result_t result;
    bdbhpt_instance_t *db = (bdbhpt_instance_t *) dbdata;
    DBT key, data;

    /* check to see if we are authoritative for the zone first. */
#if DLZ_DLOPEN_VERSION >= 3
    result = dlz_findzonedb(dbdata, name, NULL, NULL);
#else
    result = dlz_findzonedb(dbdata, name);
#endif
    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);

    switch(db->client->get(db->client, NULL, &key, &data, DB_GET_BOTH)) {
    case DB_NOTFOUND:
        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);

    return result;
}

/*%
 * Perform a zone transfer
 *
 * BDB does not allow a secondary index on a database that allows
 * duplicates.  We have a few options:
 *
 * 1) kill speed by having lookup method use a secondary db which
 * is associated to the primary DB with the DNS data.    Then have
 * another secondary db for zone transfer which also points to
 * the dns_data primary.    NO - The    point of this driver is
 * lookup performance.
 *
 * 2) Blow up database size by storing DNS data twice.  Once for
 * the lookup (dns_data) database, and a second time for the zone
 * transfer (dns_xfr) database. NO - That would probably require
 * a larger cache to provide good performance.  Also, that would
 * make the DB larger on disk potentially slowing it as well.
 *
 * 3) Loop through the dns_xfr database with a cursor to get
 * all the different hosts in a zone.    Then use the zone & host
 * together to lookup the data in the dns_data database. YES -
 * This may slow down zone xfr's a little, but that's ok they
 * don't happen as often and don't need to be as fast. We can
 * also use this table when deleting a zone (The BDB driver
 * is read only - the delete would be used during replication
 * updates by a separate process).
 */
isc_result_t
dlz_allnodes(const char *zone, void *dbdata, dns_sdlzallnodes_t *allnodes) {
    isc_result_t result = ISC_R_NOTFOUND;
    bdbhpt_instance_t *db = (bdbhpt_instance_t *) dbdata;
    DBC *xfr_cursor = NULL;
    DBC *dns_cursor = NULL;
    DBT xfr_key, xfr_data, dns_key, dns_data;
    int xfr_flags;
    int dns_flags;
    int bdbhptres;
    bdbhpt_parsed_data_t pd;
    char *tmp = NULL, *tmp_zone, *tmp_zone_host = NULL;

    memset(&xfr_key, 0, sizeof(DBT));
    memset(&xfr_data, 0, sizeof(DBT));
    memset(&dns_key, 0, sizeof(DBT));
    memset(&dns_data, 0, sizeof(DBT));

    xfr_key.data = tmp_zone = strdup(zone);
    if (xfr_key.data == NULL)
        return (ISC_R_NOMEMORY);

    xfr_key.size = strlen(xfr_key.data);

    /* get a cursor to loop through dns_xfr table */
    if (db->xfr->cursor(db->xfr, NULL, &xfr_cursor, 0) != 0) {
        result = ISC_R_FAILURE;
        goto allnodes_cleanup;
    }

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

    xfr_flags = DB_SET;

    /* loop through xfr table for specified zone. */
    while ((bdbhptres = xfr_cursor->c_get(xfr_cursor, &xfr_key,
                          &xfr_data, xfr_flags)) == 0)
    {
        xfr_flags = DB_NEXT_DUP;

        /* +1 to allow for space between zone and host names */
        dns_key.size = xfr_data.size + xfr_key.size + 1;

        /* +1 to allow for null term at end of string. */
        dns_key.data = tmp_zone_host = malloc(dns_key.size + 1);
        if (dns_key.data == NULL)
            goto allnodes_cleanup;

        /*
         * construct search key for dns_data.
         * zone_name(a space)host_name
         */
        strcpy(dns_key.data, zone);
        strcat(dns_key.data, " ");
        strncat(dns_key.data, xfr_data.data, xfr_data.size);

        dns_flags = DB_SET;

        while ((bdbhptres = dns_cursor->c_get(dns_cursor,
                              &dns_key,
                              &dns_data,
                              dns_flags)) == 0)
        {
            dns_flags = DB_NEXT_DUP;

            /* +1 to allow for null term at end of string. */
            tmp = realloc(tmp, dns_data.size + 1);
            if (tmp == NULL)
                goto allnodes_cleanup;

            /* copy data to tmp string, and append null term. */
            strncpy(tmp, dns_data.data, dns_data.size);
            tmp[dns_data.size] = '\0';

            /* split string into dns data parts. */
            if (bdbhpt_parse_data(db->log,
                          tmp, &pd) != ISC_R_SUCCESS)
                goto allnodes_cleanup;
            result = db->putnamedrr(allnodes, pd.host,
                        pd.type, pd.ttl, pd.data);
            if (result != ISC_R_SUCCESS)
                goto allnodes_cleanup;

        }    /* end inner while loop */

        /* clean up memory */
        if (tmp_zone_host != NULL) {
            free(tmp_zone_host);
            tmp_zone_host = NULL;
        }
    } /* end outer while loop */

 allnodes_cleanup:
    /* free any memory */
    if (tmp != NULL)
        free(tmp);

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

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

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

    if (dns_cursor != NULL)
        dns_cursor->c_close(dns_cursor);

    return result;
}

/*%
 * Performs bdbhpt cleanup.
 * Used by bdbhpt_create if there is an error starting up.
 * Used by bdbhpt_destroy when the driver is shutting down.
 */
static void
bdbhpt_cleanup(bdbhpt_instance_t *db) {
    /* close databases */
    if (db->data != NULL)
        db->data->close(db->data, 0);
    if (db->xfr != NULL)
        db->xfr->close(db->xfr, 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);
}

/*
 * See if we handle a given zone
 */
#if DLZ_DLOPEN_VERSION < 3
isc_result_t
dlz_findzonedb(void *dbdata, const char *name)
#else
isc_result_t
dlz_findzonedb(void *dbdata, const char *name,
         dns_clientinfomethods_t *methods,
         dns_clientinfo_t *clientinfo)
#endif
{
    isc_result_t result;
    bdbhpt_instance_t *db = (bdbhpt_instance_t *) dbdata;
    DBT key, data;

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

#if DLZ_DLOPEN_VERSION >= 3
    UNUSED(methods);
    UNUSED(clientinfo);
#endif

    key.data = strdup(name);

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

    /*
     * reverse string to take advantage of BDB locality of reference
     * if we need futher lookups because the zone doesn't match the
     * first time.
     */
    key.data = bdbhpt_strrev(key.data);
    key.size = strlen(key.data);

    switch(db->zone->get(db->zone, NULL, &key, &data, 0)) {
    case DB_NOTFOUND:
        result = ISC_R_NOTFOUND;
        break;
    case 0:
        result = ISC_R_SUCCESS;
        break;
    default:
        result = ISC_R_FAILURE;
    }

    /* 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);

    return result;
}

/*
 * Look up one record in the database.
 *
 */
#if DLZ_DLOPEN_VERSION == 1
isc_result_t dlz_lookup(const char *zone, const char *name,
            void *dbdata, dns_sdlzlookup_t *lookup)
#else
isc_result_t dlz_lookup(const char *zone, const char *name, void *dbdata,
            dns_sdlzlookup_t *lookup,
            dns_clientinfomethods_t *methods,
            dns_clientinfo_t *clientinfo)
#endif
{
    isc_result_t result = ISC_R_NOTFOUND;
    bdbhpt_instance_t *db = (bdbhpt_instance_t *) dbdata;
    DBC *data_cursor = NULL;
    DBT key, data;
    int bdbhptres;
    int flags;

    bdbhpt_parsed_data_t pd;
    char *tmp = NULL;
    char *keyStr = NULL;

#if DLZ_DLOPEN_VERSION >= 2
    UNUSED(methods);
    UNUSED(clientinfo);
#endif

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

    key.size = strlen(zone) + strlen(name) + 1;

    /* allocate mem for key */
    key.data = keyStr = malloc((key.size + 1) * sizeof(char));

    if (keyStr == NULL)
        return ISC_R_NOMEMORY;

    strcpy(keyStr, zone);
    strcat(keyStr, " ");
    strcat(keyStr, name);

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

    result = ISC_R_NOTFOUND;

    flags = DB_SET;
    while ((bdbhptres = data_cursor->c_get(data_cursor, &key, &data,
                           flags)) == 0)
    {
        flags = DB_NEXT_DUP;
        tmp = realloc(tmp, data.size + 1);
        if (tmp == NULL)
            goto lookup_cleanup;

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

        if (bdbhpt_parse_data(db->log, tmp, &pd) != ISC_R_SUCCESS)
            goto lookup_cleanup;

        result = db->putrr(lookup, pd.type, pd.ttl, pd.data);
        if (result != ISC_R_SUCCESS)
            goto lookup_cleanup;
    } /* end while loop */

 lookup_cleanup:
    /* get rid of cursor */
    if (data_cursor != NULL)
        data_cursor->c_close(data_cursor);

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

    return result;
}

/*%
 * Initialises, sets flags and then opens Berkeley databases.
 */
static isc_result_t
bdbhpt_opendb(log_t *log, DB_ENV *db_env, DBTYPE db_type, DB **db,
          const char *db_name, char *db_file, int flags)
{
    int result;

    /* Initialise the database. */
    if ((result = db_create(db, db_env, 0)) != 0) {
        log(ISC_LOG_ERROR,
            "bdbhpt_dynamic: could not initialize %s database. "
            "BerkeleyDB error: %s",
            db_name, db_strerror(result));
        return ISC_R_FAILURE;
    }

    /* set database flags. */
    if ((result = (*db)->set_flags(*db, flags)) != 0) {
        log(ISC_LOG_ERROR,
            "bdbhpt_dynamic: could not set flags for %s database. "
            "BerkeleyDB 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 | bdbhpt_threads, 0)) != 0) {
        log(ISC_LOG_ERROR,
            "bdbhpt_dynamic: could not open %s database in %s. "
            "BerkeleyDB error: %s",
            db_name, db_file, db_strerror(result));
        return ISC_R_FAILURE;
    }

    return ISC_R_SUCCESS;
}


/*
 * Called to initialize the driver
 */
isc_result_t
dlz_create(const char *dlzname, unsigned int argc, char *argv[],
         void **dbdata, ...)
{
    isc_result_t result;
    int bdbhptres;
    int bdbFlags = 0;
    bdbhpt_instance_t *db = NULL;

    const char *helper_name;
    va_list ap;

    UNUSED(dlzname);

    /* Allocate memory for our db structures and helper functions */
    db = calloc(1, sizeof(struct bdbhpt_instance));
    if (db == NULL)
        return (ISC_R_NOMEMORY);

    /* Fill in the helper functions */
    va_start(ap, dbdata);
    while ((helper_name = va_arg(ap, const char *)) != NULL)
        b9_add_helper(db, helper_name, va_arg(ap, void*));
    va_end(ap);

    /* verify we have 4 arg's passed to the driver */
    if (argc != 4) {
        db->log(ISC_LOG_ERROR,
            "bdbhpt_dynamic: please supply 3 command line args. "
            "You supplied: %s", argc);
        return (ISC_R_FAILURE);
    }

    switch((char) *argv[1]) {
        /*
         * Transactional mode.  Highest safety - lowest speed.
         */
    case 'T':
    case 't':
        bdbFlags = DB_INIT_MPOOL | DB_INIT_LOCK |
            DB_INIT_LOG | DB_INIT_TXN;
        db->log(ISC_LOG_INFO,
            "bdbhpt_dynamic: using transactional mode.");
        break;

        /*
         * Concurrent mode.  Lower safety (no rollback) -
         * higher speed.
         */
    case 'C':
    case 'c':
        bdbFlags = DB_INIT_CDB | DB_INIT_MPOOL;
        db->log(ISC_LOG_INFO,
            "bdbhpt_dynamic: using concurrent mode.");
        break;

        /*
         * Private mode. No inter-process communication & no locking.
         * Lowest saftey - highest speed.
         */
    case 'P':
    case 'p':
        bdbFlags = DB_PRIVATE | DB_INIT_MPOOL;
        db->log(ISC_LOG_INFO,
            "bdbhpt_dynamic: using private mode.");
        break;
    default:
        db->log(ISC_LOG_ERROR,
            "bdbhpt_dynamic: "
            "operating mode must be set to P or C or T. "
            "You specified '%s'", argv[1]);
        return (ISC_R_FAILURE);
    }

    /*
     * create bdbhpt environment
     * Basically bdbhpt allocates and assigns memory to db->dbenv
     */
    bdbhptres = db_env_create(&db->dbenv, 0);
    if (bdbhptres != 0) {
        db->log(ISC_LOG_ERROR,
            "bdbhpt_dynamic: db environment could not be created. "
            "BerkeleyDB error: %s", db_strerror(bdbhptres));
        result = ISC_R_FAILURE;
        goto init_cleanup;
    }

    /* open bdbhpt environment */
    bdbhptres = db->dbenv->open(db->dbenv, argv[2],
                    bdbFlags | bdbhpt_threads | DB_CREATE, 0);
    if (bdbhptres != 0) {
        db->log(ISC_LOG_ERROR,
            "bdbhpt_dynamic: "
            "db environment at '%s' could not be opened. "
            "BerkeleyDB error: %s",
            argv[2], db_strerror(bdbhptres));
        result = ISC_R_FAILURE;
        goto init_cleanup;
    }

    /* open dlz_data database. */
    result = bdbhpt_opendb(db->log, db->dbenv, DB_UNKNOWN, &db->data,
                   dlz_data, argv[3], DB_DUP | DB_DUPSORT);
    if (result != ISC_R_SUCCESS)
        goto init_cleanup;

    /* open dlz_xfr database. */
    result = bdbhpt_opendb(db->log, db->dbenv, DB_UNKNOWN, &db->xfr,
                   dlz_xfr, argv[3], DB_DUP | DB_DUPSORT);
    if (result != ISC_R_SUCCESS)
        goto init_cleanup;

    /* open dlz_zone database. */
    result = bdbhpt_opendb(db->log, db->dbenv, DB_UNKNOWN, &db->zone,
                   dlz_zone, argv[3], 0);
    if (result != ISC_R_SUCCESS)
        goto init_cleanup;

    /* open dlz_client database. */
    result = bdbhpt_opendb(db->log, db->dbenv, DB_UNKNOWN, &db->client,
                   dlz_client, argv[3], DB_DUP | DB_DUPSORT);
    if (result != ISC_R_SUCCESS)
        goto init_cleanup;

    *dbdata = db;

    db->log(ISC_LOG_INFO,
        "bdbhpt_dynamic: version %s, started",
        dlz_bdbhpt_dynamic_version);
    return(ISC_R_SUCCESS);

 init_cleanup:
    bdbhpt_cleanup(db);
    return result;
}

/*
 * Shut down the backend
 */
void
dlz_destroy(void *dbdata) {
    struct bdbhpt_instance *db = (struct bdbhpt_instance *)dbdata;

    db->log(ISC_LOG_INFO,
        "dlz_bdbhpt_dynamic (%s): shutting down",
        dlz_bdbhpt_dynamic_version);
    bdbhpt_cleanup((bdbhpt_instance_t *) dbdata);
    free(db);
}

/*
 * Return the version of the API
 */
int
dlz_version(unsigned int *flags) {
    UNUSED(flags);
    return (DLZ_DLOPEN_VERSION);
}

/*
 * Register a helper function from the bind9 dlz_dlopen driver
 */
static void
b9_add_helper(struct bdbhpt_instance *db, const char *helper_name, void *ptr) {
    if (strcmp(helper_name, "log") == 0)
        db->log = (log_t *)ptr;
    if (strcmp(helper_name, "putrr") == 0)
        db->putrr = (dns_sdlz_putrr_t *)ptr;
    if (strcmp(helper_name, "putnamedrr") == 0)
        db->putnamedrr = (dns_sdlz_putnamedrr_t *)ptr;
    if (strcmp(helper_name, "writeable_zone") == 0)
        db->writeable_zone = (dns_dlz_writeablezone_t *)ptr;
}