sdlz.c

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/*
 * Portions Copyright (C) 2005-2015  Internet Systems Consortium, Inc. ("ISC")
 * Portions Copyright (C) 1999-2001  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.
 */

/*
 * 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.
 */

/* $Id$ */

/*! \file */

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

#include <isc/buffer.h>
#include <isc/lex.h>
#include <isc/log.h>
#include <isc/rwlock.h>
#include <isc/string.h>
#include <isc/util.h>
#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/once.h>
#include <isc/print.h>
#include <isc/region.h>

#include <dns/callbacks.h>
#include <dns/db.h>
#include <dns/dbiterator.h>
#include <dns/dlz.h>
#include <dns/fixedname.h>
#include <dns/log.h>
#include <dns/rdata.h>
#include <dns/rdatalist.h>
#include <dns/rdataset.h>
#include <dns/rdatasetiter.h>
#include <dns/rdatatype.h>
#include <dns/result.h>
#include <dns/master.h>
#include <dns/sdlz.h>
#include <dns/types.h>

#include "rdatalist_p.h"

/*
 * Private Types
 */

struct dns_sdlzimplementation {
        const dns_sdlzmethods_t         *methods;
        isc_mem_t                       *mctx;
        void                            *driverarg;
        unsigned int                    flags;
        isc_mutex_t                     driverlock;
        dns_dlzimplementation_t         *dlz_imp;
};

struct dns_sdlz_db {
        /* Unlocked */
        dns_db_t                        common;
        void                            *dbdata;
        dns_sdlzimplementation_t        *dlzimp;
        isc_mutex_t                     refcnt_lock;
        /* Locked */
        unsigned int                    references;
        dns_dbversion_t                 *future_version;
        int                             dummy_version;
};

struct dns_sdlzlookup {
        /* Unlocked */
        unsigned int                    magic;
        dns_sdlz_db_t                   *sdlz;
        ISC_LIST(dns_rdatalist_t)       lists;
        ISC_LIST(isc_buffer_t)          buffers;
        dns_name_t                      *name;
        ISC_LINK(dns_sdlzlookup_t)      link;
        isc_mutex_t                     lock;
        dns_rdatacallbacks_t            callbacks;
        /* Locked */
        unsigned int                    references;
};

typedef struct dns_sdlzlookup dns_sdlznode_t;

struct dns_sdlzallnodes {
        dns_dbiterator_t                common;
        ISC_LIST(dns_sdlznode_t)        nodelist;
        dns_sdlznode_t                  *current;
        dns_sdlznode_t                  *origin;
};

typedef dns_sdlzallnodes_t sdlz_dbiterator_t;

typedef struct sdlz_rdatasetiter {
        dns_rdatasetiter_t              common;
        dns_rdatalist_t                 *current;
} sdlz_rdatasetiter_t;


#define SDLZDB_MAGIC            ISC_MAGIC('D', 'L', 'Z', 'S')

/*
 * Note that "impmagic" is not the first four bytes of the struct, so
 * ISC_MAGIC_VALID cannot be used.
 */

#define VALID_SDLZDB(sdlzdb)    ((sdlzdb) != NULL && \
                                 (sdlzdb)->common.impmagic == SDLZDB_MAGIC)

#define SDLZLOOKUP_MAGIC        ISC_MAGIC('D','L','Z','L')
#define VALID_SDLZLOOKUP(sdlzl) ISC_MAGIC_VALID(sdlzl, SDLZLOOKUP_MAGIC)
#define VALID_SDLZNODE(sdlzn)   VALID_SDLZLOOKUP(sdlzn)

/* These values are taken from RFC 1537 */
#define SDLZ_DEFAULT_REFRESH    (60 * 60 * 8)
#define SDLZ_DEFAULT_RETRY      (60 * 60 * 2)
#define SDLZ_DEFAULT_EXPIRE     (60 * 60 * 24 * 7)
#define SDLZ_DEFAULT_MINIMUM    (60 * 60 * 24)

/* This is a reasonable value */
#define SDLZ_DEFAULT_TTL        (60 * 60 * 24)

#ifdef __COVERITY__
#define MAYBE_LOCK(imp) LOCK(&imp->driverlock)
#define MAYBE_UNLOCK(imp) UNLOCK(&imp->driverlock)
#else
#define MAYBE_LOCK(imp) \
        do { \
                unsigned int flags = imp->flags; \
                if ((flags & DNS_SDLZFLAG_THREADSAFE) == 0) \
                        LOCK(&imp->driverlock); \
        } while (0)

#define MAYBE_UNLOCK(imp) \
        do { \
                unsigned int flags = imp->flags; \
                if ((flags & DNS_SDLZFLAG_THREADSAFE) == 0) \
                        UNLOCK(&imp->driverlock); \
        } while (0)
#endif

/*
 * Forward references.
 */
static isc_result_t getnodedata(dns_db_t *db, dns_name_t *name,
                                isc_boolean_t create, unsigned int options,
                                dns_clientinfomethods_t *methods,
                                dns_clientinfo_t *clientinfo,
                                dns_dbnode_t **nodep);

static void list_tordataset(dns_rdatalist_t *rdatalist,
                            dns_db_t *db, dns_dbnode_t *node,
                            dns_rdataset_t *rdataset);

static void detachnode(dns_db_t *db, dns_dbnode_t **targetp);

static void             dbiterator_destroy(dns_dbiterator_t **iteratorp);
static isc_result_t     dbiterator_first(dns_dbiterator_t *iterator);
static isc_result_t     dbiterator_last(dns_dbiterator_t *iterator);
static isc_result_t     dbiterator_seek(dns_dbiterator_t *iterator,
                                        dns_name_t *name);
static isc_result_t     dbiterator_prev(dns_dbiterator_t *iterator);
static isc_result_t     dbiterator_next(dns_dbiterator_t *iterator);
static isc_result_t     dbiterator_current(dns_dbiterator_t *iterator,
                                           dns_dbnode_t **nodep,
                                           dns_name_t *name);
static isc_result_t     dbiterator_pause(dns_dbiterator_t *iterator);
static isc_result_t     dbiterator_origin(dns_dbiterator_t *iterator,
                                          dns_name_t *name);

static dns_dbiteratormethods_t dbiterator_methods = {
        dbiterator_destroy,
        dbiterator_first,
        dbiterator_last,
        dbiterator_seek,
        dbiterator_prev,
        dbiterator_next,
        dbiterator_current,
        dbiterator_pause,
        dbiterator_origin
};

/*
 * Utility functions
 */

/*
 * Log a message at the given level
 */
static void
sdlz_log(int level, const char *fmt, ...) {
        va_list ap;
        va_start(ap, fmt);
        isc_log_vwrite(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                       DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(level),
                       fmt, ap);
        va_end(ap);
}

/*% Converts the input string to lowercase, in place. */
static void
dns_sdlz_tolower(char *str) {
        unsigned int len = strlen(str);
        unsigned int i;

        for (i = 0; i < len; i++) {
                if (str[i] >= 'A' && str[i] <= 'Z')
                        str[i] += 32;
        }
}

static inline unsigned int
initial_size(const char *data) {
        unsigned int len = (strlen(data) / 64) + 1;
        return (len * 64 + 64);
}

/*
 * Rdataset Iterator Methods. These methods were "borrowed" from the SDB
 * driver interface.  See the SDB driver interface documentation for more info.
 */

static void
rdatasetiter_destroy(dns_rdatasetiter_t **iteratorp) {
        sdlz_rdatasetiter_t *sdlziterator =
                (sdlz_rdatasetiter_t *)(*iteratorp);

        detachnode(sdlziterator->common.db, &sdlziterator->common.node);
        isc_mem_put(sdlziterator->common.db->mctx, sdlziterator,
                    sizeof(sdlz_rdatasetiter_t));
        *iteratorp = NULL;
}

static isc_result_t
rdatasetiter_first(dns_rdatasetiter_t *iterator) {
        sdlz_rdatasetiter_t *sdlziterator = (sdlz_rdatasetiter_t *)iterator;
        dns_sdlznode_t *sdlznode = (dns_sdlznode_t *)iterator->node;

        if (ISC_LIST_EMPTY(sdlznode->lists))
                return (ISC_R_NOMORE);
        sdlziterator->current = ISC_LIST_HEAD(sdlznode->lists);
        return (ISC_R_SUCCESS);
}

static isc_result_t
rdatasetiter_next(dns_rdatasetiter_t *iterator) {
        sdlz_rdatasetiter_t *sdlziterator = (sdlz_rdatasetiter_t *)iterator;

        sdlziterator->current = ISC_LIST_NEXT(sdlziterator->current, link);
        if (sdlziterator->current == NULL)
                return (ISC_R_NOMORE);
        else
                return (ISC_R_SUCCESS);
}

static void
rdatasetiter_current(dns_rdatasetiter_t *iterator, dns_rdataset_t *rdataset) {
        sdlz_rdatasetiter_t *sdlziterator = (sdlz_rdatasetiter_t *)iterator;

        list_tordataset(sdlziterator->current, iterator->db, iterator->node,
                        rdataset);
}

static dns_rdatasetitermethods_t rdatasetiter_methods = {
        rdatasetiter_destroy,
        rdatasetiter_first,
        rdatasetiter_next,
        rdatasetiter_current
};

/*
 * DB routines. These methods were "borrowed" from the SDB driver interface.
 * See the SDB driver interface documentation for more info.
 */

static void
attach(dns_db_t *source, dns_db_t **targetp) {
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *) source;

        REQUIRE(VALID_SDLZDB(sdlz));

        LOCK(&sdlz->refcnt_lock);
        REQUIRE(sdlz->references > 0);
        sdlz->references++;
        UNLOCK(&sdlz->refcnt_lock);

        *targetp = source;
}

static void
destroy(dns_sdlz_db_t *sdlz) {
        isc_mem_t *mctx;
        mctx = sdlz->common.mctx;

        sdlz->common.magic = 0;
        sdlz->common.impmagic = 0;

        (void)isc_mutex_destroy(&sdlz->refcnt_lock);

        dns_name_free(&sdlz->common.origin, mctx);

        isc_mem_put(mctx, sdlz, sizeof(dns_sdlz_db_t));
        isc_mem_detach(&mctx);
}

static void
detach(dns_db_t **dbp) {
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)(*dbp);
        isc_boolean_t need_destroy = ISC_FALSE;

        REQUIRE(VALID_SDLZDB(sdlz));
        LOCK(&sdlz->refcnt_lock);
        REQUIRE(sdlz->references > 0);
        sdlz->references--;
        if (sdlz->references == 0)
                need_destroy = ISC_TRUE;
        UNLOCK(&sdlz->refcnt_lock);

        if (need_destroy)
                destroy(sdlz);

        *dbp = NULL;
}

static isc_result_t
beginload(dns_db_t *db, dns_rdatacallbacks_t *callbacks) {
        UNUSED(db);
        UNUSED(callbacks);
        return (ISC_R_NOTIMPLEMENTED);
}

static isc_result_t
endload(dns_db_t *db, dns_rdatacallbacks_t *callbacks) {
        UNUSED(db);
        UNUSED(callbacks);
        return (ISC_R_NOTIMPLEMENTED);
}

static isc_result_t
dump(dns_db_t *db, dns_dbversion_t *version, const char *filename,
     dns_masterformat_t masterformat)
{
        UNUSED(db);
        UNUSED(version);
        UNUSED(filename);
        UNUSED(masterformat);
        return (ISC_R_NOTIMPLEMENTED);
}

static void
currentversion(dns_db_t *db, dns_dbversion_t **versionp) {
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        REQUIRE(VALID_SDLZDB(sdlz));
        REQUIRE(versionp != NULL && *versionp == NULL);

        *versionp = (void *) &sdlz->dummy_version;
        return;
}

static isc_result_t
newversion(dns_db_t *db, dns_dbversion_t **versionp) {
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        char origin[DNS_NAME_MAXTEXT + 1];
        isc_result_t result;

        REQUIRE(VALID_SDLZDB(sdlz));

        if (sdlz->dlzimp->methods->newversion == NULL)
                return (ISC_R_NOTIMPLEMENTED);

        dns_name_format(&sdlz->common.origin, origin, sizeof(origin));

        result = sdlz->dlzimp->methods->newversion(origin,
                                                   sdlz->dlzimp->driverarg,
                                                   sdlz->dbdata, versionp);
        if (result != ISC_R_SUCCESS) {
                sdlz_log(ISC_LOG_ERROR,
                         "sdlz newversion on origin %s failed : %s",
                         origin, isc_result_totext(result));
                return (result);
        }

        sdlz->future_version = *versionp;
        return (ISC_R_SUCCESS);
}

static void
attachversion(dns_db_t *db, dns_dbversion_t *source, dns_dbversion_t **targetp)
{
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;

        REQUIRE(VALID_SDLZDB(sdlz));
        REQUIRE(source != NULL && source == (void *)&sdlz->dummy_version);

        *targetp = source;
}

static void
closeversion(dns_db_t *db, dns_dbversion_t **versionp, isc_boolean_t commit) {
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        char origin[DNS_NAME_MAXTEXT + 1];

        REQUIRE(VALID_SDLZDB(sdlz));
        REQUIRE(versionp != NULL);

        if (*versionp == (void *)&sdlz->dummy_version) {
                *versionp = NULL;
                return;
        }

        REQUIRE(*versionp == sdlz->future_version);
        REQUIRE(sdlz->dlzimp->methods->closeversion != NULL);

        dns_name_format(&sdlz->common.origin, origin, sizeof(origin));

        sdlz->dlzimp->methods->closeversion(origin, commit,
                                            sdlz->dlzimp->driverarg,
                                            sdlz->dbdata, versionp);
        if (*versionp != NULL)
                sdlz_log(ISC_LOG_ERROR,
                        "sdlz closeversion on origin %s failed", origin);

        sdlz->future_version = NULL;
}

static isc_result_t
createnode(dns_sdlz_db_t *sdlz, dns_sdlznode_t **nodep) {
        dns_sdlznode_t *node;
        isc_result_t result;

        node = isc_mem_get(sdlz->common.mctx, sizeof(dns_sdlznode_t));
        if (node == NULL)
                return (ISC_R_NOMEMORY);

        node->sdlz = NULL;
        attach((dns_db_t *)sdlz, (dns_db_t **)&node->sdlz);
        ISC_LIST_INIT(node->lists);
        ISC_LIST_INIT(node->buffers);
        ISC_LINK_INIT(node, link);
        node->name = NULL;
        result = isc_mutex_init(&node->lock);
        if (result != ISC_R_SUCCESS) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "isc_mutex_init() failed: %s",
                                 isc_result_totext(result));
                isc_mem_put(sdlz->common.mctx, node, sizeof(dns_sdlznode_t));
                return (ISC_R_UNEXPECTED);
        }
        dns_rdatacallbacks_init(&node->callbacks);
        node->references = 1;
        node->magic = SDLZLOOKUP_MAGIC;

        *nodep = node;
        return (ISC_R_SUCCESS);
}

static void
destroynode(dns_sdlznode_t *node) {
        dns_rdatalist_t *list;
        dns_rdata_t *rdata;
        isc_buffer_t *b;
        dns_sdlz_db_t *sdlz;
        dns_db_t *db;
        isc_mem_t *mctx;

        sdlz = node->sdlz;
        mctx = sdlz->common.mctx;

        while (!ISC_LIST_EMPTY(node->lists)) {
                list = ISC_LIST_HEAD(node->lists);
                while (!ISC_LIST_EMPTY(list->rdata)) {
                        rdata = ISC_LIST_HEAD(list->rdata);
                        ISC_LIST_UNLINK(list->rdata, rdata, link);
                        isc_mem_put(mctx, rdata, sizeof(dns_rdata_t));
                }
                ISC_LIST_UNLINK(node->lists, list, link);
                isc_mem_put(mctx, list, sizeof(dns_rdatalist_t));
        }

        while (!ISC_LIST_EMPTY(node->buffers)) {
                b = ISC_LIST_HEAD(node->buffers);
                ISC_LIST_UNLINK(node->buffers, b, link);
                isc_buffer_free(&b);
        }

        if (node->name != NULL) {
                dns_name_free(node->name, mctx);
                isc_mem_put(mctx, node->name, sizeof(dns_name_t));
        }
        DESTROYLOCK(&node->lock);
        node->magic = 0;
        isc_mem_put(mctx, node, sizeof(dns_sdlznode_t));
        db = &sdlz->common;
        detach(&db);
}

static isc_result_t
getnodedata(dns_db_t *db, dns_name_t *name, isc_boolean_t create,
            unsigned int options, dns_clientinfomethods_t *methods,
            dns_clientinfo_t *clientinfo, dns_dbnode_t **nodep)
{
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        dns_sdlznode_t *node = NULL;
        isc_result_t result;
        isc_buffer_t b;
        char namestr[DNS_NAME_MAXTEXT + 1];
        isc_buffer_t b2;
        char zonestr[DNS_NAME_MAXTEXT + 1];
        isc_boolean_t isorigin;
        dns_sdlzauthorityfunc_t authority;

        REQUIRE(VALID_SDLZDB(sdlz));
        REQUIRE(nodep != NULL && *nodep == NULL);

        if (sdlz->dlzimp->methods->newversion == NULL) {
                REQUIRE(create == ISC_FALSE);
        }

        isc_buffer_init(&b, namestr, sizeof(namestr));
        if ((sdlz->dlzimp->flags & DNS_SDLZFLAG_RELATIVEOWNER) != 0) {
                dns_name_t relname;
                unsigned int labels;

                labels = dns_name_countlabels(name) -
                         dns_name_countlabels(&sdlz->common.origin);
                dns_name_init(&relname, NULL);
                dns_name_getlabelsequence(name, 0, labels, &relname);
                result = dns_name_totext(&relname, ISC_TRUE, &b);
                if (result != ISC_R_SUCCESS)
                        return (result);
        } else {
                result = dns_name_totext(name, ISC_TRUE, &b);
                if (result != ISC_R_SUCCESS)
                        return (result);
        }
        isc_buffer_putuint8(&b, 0);

        isc_buffer_init(&b2, zonestr, sizeof(zonestr));
        result = dns_name_totext(&sdlz->common.origin, ISC_TRUE, &b2);
        if (result != ISC_R_SUCCESS)
                return (result);
        isc_buffer_putuint8(&b2, 0);

        result = createnode(sdlz, &node);
        if (result != ISC_R_SUCCESS)
                return (result);

        isorigin = dns_name_equal(name, &sdlz->common.origin);

        /* make sure strings are always lowercase */
        dns_sdlz_tolower(zonestr);
        dns_sdlz_tolower(namestr);

        MAYBE_LOCK(sdlz->dlzimp);

        /* try to lookup the host (namestr) */
        result = sdlz->dlzimp->methods->lookup(zonestr, namestr,
                                               sdlz->dlzimp->driverarg,
                                               sdlz->dbdata, node,
                                               methods, clientinfo);

        /*
         * If the name was not found and DNS_DBFIND_NOWILD is not
         * set, then we try to find a wildcard entry.
         *
         * If DNS_DBFIND_NOZONECUT is set and there are multiple
         * levels between the host and the zone origin, we also look
         * for wildcards at each level.
         */
        if (result == ISC_R_NOTFOUND && !create &&
            (options & DNS_DBFIND_NOWILD) == 0)
        {
                unsigned int i, dlabels, nlabels;

                nlabels = dns_name_countlabels(name);
                dlabels = nlabels - dns_name_countlabels(&sdlz->common.origin);
                for (i = 0; i < dlabels; i++) {
                        char wildstr[DNS_NAME_MAXTEXT + 1];
                        dns_fixedname_t fixed;
                        dns_name_t *wild;

                        dns_fixedname_init(&fixed);
                        if (i == dlabels)
                                wild = dns_wildcardname;
                        else {
                                wild = dns_fixedname_name(&fixed);
                                dns_name_getlabelsequence(name, i + 1,
                                                          dlabels - i - 1,
                                                          wild);
                                result = dns_name_concatenate(dns_wildcardname,
                                                              wild, wild, NULL);
                                if (result != ISC_R_SUCCESS)
                                        return (result);
                        }

                        isc_buffer_init(&b, wildstr, sizeof(wildstr));
                        result = dns_name_totext(wild, ISC_TRUE, &b);
                        if (result != ISC_R_SUCCESS)
                                return (result);
                        isc_buffer_putuint8(&b, 0);

                        result = sdlz->dlzimp->methods->lookup(zonestr, wildstr,
                                                       sdlz->dlzimp->driverarg,
                                                       sdlz->dbdata, node,
                                                       methods, clientinfo);
                        if (result == ISC_R_SUCCESS)
                                break;
                }
        }

        MAYBE_UNLOCK(sdlz->dlzimp);

        if (result == ISC_R_NOTFOUND && (isorigin || create))
                result = ISC_R_SUCCESS;

        if (result != ISC_R_SUCCESS) {
                destroynode(node);
                return (result);
        }

        if (isorigin && sdlz->dlzimp->methods->authority != NULL) {
                MAYBE_LOCK(sdlz->dlzimp);
                authority = sdlz->dlzimp->methods->authority;
                result = (*authority)(zonestr, sdlz->dlzimp->driverarg,
                                      sdlz->dbdata, node);
                MAYBE_UNLOCK(sdlz->dlzimp);
                if (result != ISC_R_SUCCESS &&
                    result != ISC_R_NOTIMPLEMENTED)
                {
                        destroynode(node);
                        return (result);
                }
        }

        if (node->name == NULL) {
                node->name = isc_mem_get(sdlz->common.mctx,
                                         sizeof(dns_name_t));
                if (node->name == NULL) {
                        destroynode(node);
                        return (ISC_R_NOMEMORY);
                }
                dns_name_init(node->name, NULL);
                result = dns_name_dup(name, sdlz->common.mctx, node->name);
                if (result != ISC_R_SUCCESS) {
                        isc_mem_put(sdlz->common.mctx, node->name,
                                    sizeof(dns_name_t));
                        destroynode(node);
                        return (result);
                }
        }

        *nodep = node;
        return (ISC_R_SUCCESS);
}

static isc_result_t
findnodeext(dns_db_t *db, dns_name_t *name, isc_boolean_t create,
            dns_clientinfomethods_t *methods, dns_clientinfo_t *clientinfo,
            dns_dbnode_t **nodep)
{
        return (getnodedata(db, name, create, 0, methods, clientinfo, nodep));
}

static isc_result_t
findnode(dns_db_t *db, dns_name_t *name, isc_boolean_t create,
         dns_dbnode_t **nodep)
{
        return (getnodedata(db, name, create, 0, NULL, NULL, nodep));
}

static isc_result_t
findzonecut(dns_db_t *db, dns_name_t *name, unsigned int options,
            isc_stdtime_t now, dns_dbnode_t **nodep, dns_name_t *foundname,
            dns_rdataset_t *rdataset, dns_rdataset_t *sigrdataset)
{
        UNUSED(db);
        UNUSED(name);
        UNUSED(options);
        UNUSED(now);
        UNUSED(nodep);
        UNUSED(foundname);
        UNUSED(rdataset);
        UNUSED(sigrdataset);

        return (ISC_R_NOTIMPLEMENTED);
}

static void
attachnode(dns_db_t *db, dns_dbnode_t *source, dns_dbnode_t **targetp) {
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        dns_sdlznode_t *node = (dns_sdlznode_t *)source;

        REQUIRE(VALID_SDLZDB(sdlz));

        UNUSED(sdlz);

        LOCK(&node->lock);
        INSIST(node->references > 0);
        node->references++;
        INSIST(node->references != 0);          /* Catch overflow. */
        UNLOCK(&node->lock);

        *targetp = source;
}

static void
detachnode(dns_db_t *db, dns_dbnode_t **targetp) {
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        dns_sdlznode_t *node;
        isc_boolean_t need_destroy = ISC_FALSE;

        REQUIRE(VALID_SDLZDB(sdlz));
        REQUIRE(targetp != NULL && *targetp != NULL);

        UNUSED(sdlz);

        node = (dns_sdlznode_t *)(*targetp);

        LOCK(&node->lock);
        INSIST(node->references > 0);
        node->references--;
        if (node->references == 0)
                need_destroy = ISC_TRUE;
        UNLOCK(&node->lock);

        if (need_destroy)
                destroynode(node);

        *targetp = NULL;
}

static isc_result_t
expirenode(dns_db_t *db, dns_dbnode_t *node, isc_stdtime_t now) {
        UNUSED(db);
        UNUSED(node);
        UNUSED(now);
        INSIST(0);
        return (ISC_R_UNEXPECTED);
}

static void
printnode(dns_db_t *db, dns_dbnode_t *node, FILE *out) {
        UNUSED(db);
        UNUSED(node);
        UNUSED(out);
        return;
}

static isc_result_t
createiterator(dns_db_t *db, unsigned int options, dns_dbiterator_t **iteratorp)
{
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        sdlz_dbiterator_t *sdlziter;
        isc_result_t result;
        isc_buffer_t b;
        char zonestr[DNS_NAME_MAXTEXT + 1];

        REQUIRE(VALID_SDLZDB(sdlz));

        if (sdlz->dlzimp->methods->allnodes == NULL)
                return (ISC_R_NOTIMPLEMENTED);

        if ((options & DNS_DB_NSEC3ONLY) != 0 ||
            (options & DNS_DB_NONSEC3) != 0)
                 return (ISC_R_NOTIMPLEMENTED);

        isc_buffer_init(&b, zonestr, sizeof(zonestr));
        result = dns_name_totext(&sdlz->common.origin, ISC_TRUE, &b);
        if (result != ISC_R_SUCCESS)
                return (result);
        isc_buffer_putuint8(&b, 0);

        sdlziter = isc_mem_get(sdlz->common.mctx, sizeof(sdlz_dbiterator_t));
        if (sdlziter == NULL)
                return (ISC_R_NOMEMORY);

        sdlziter->common.methods = &dbiterator_methods;
        sdlziter->common.db = NULL;
        dns_db_attach(db, &sdlziter->common.db);
        sdlziter->common.relative_names = ISC_TF(options & DNS_DB_RELATIVENAMES);
        sdlziter->common.magic = DNS_DBITERATOR_MAGIC;
        ISC_LIST_INIT(sdlziter->nodelist);
        sdlziter->current = NULL;
        sdlziter->origin = NULL;

        /* make sure strings are always lowercase */
        dns_sdlz_tolower(zonestr);

        MAYBE_LOCK(sdlz->dlzimp);
        result = sdlz->dlzimp->methods->allnodes(zonestr,
                                                 sdlz->dlzimp->driverarg,
                                                 sdlz->dbdata, sdlziter);
        MAYBE_UNLOCK(sdlz->dlzimp);
        if (result != ISC_R_SUCCESS) {
                dns_dbiterator_t *iter = &sdlziter->common;
                dbiterator_destroy(&iter);
                return (result);
        }

        if (sdlziter->origin != NULL) {
                ISC_LIST_UNLINK(sdlziter->nodelist, sdlziter->origin, link);
                ISC_LIST_PREPEND(sdlziter->nodelist, sdlziter->origin, link);
        }

        *iteratorp = (dns_dbiterator_t *)sdlziter;

        return (ISC_R_SUCCESS);
}

static isc_result_t
findrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
             dns_rdatatype_t type, dns_rdatatype_t covers,
             isc_stdtime_t now, dns_rdataset_t *rdataset,
             dns_rdataset_t *sigrdataset)
{
        dns_rdatalist_t *list;
        dns_sdlznode_t *sdlznode = (dns_sdlznode_t *)node;

        REQUIRE(VALID_SDLZNODE(node));

        UNUSED(db);
        UNUSED(version);
        UNUSED(covers);
        UNUSED(now);
        UNUSED(sigrdataset);

        if (type == dns_rdatatype_sig || type == dns_rdatatype_rrsig)
                return (ISC_R_NOTIMPLEMENTED);

        list = ISC_LIST_HEAD(sdlznode->lists);
        while (list != NULL) {
                if (list->type == type)
                        break;
                list = ISC_LIST_NEXT(list, link);
        }
        if (list == NULL)
                return (ISC_R_NOTFOUND);

        list_tordataset(list, db, node, rdataset);

        return (ISC_R_SUCCESS);
}

static isc_result_t
findext(dns_db_t *db, dns_name_t *name, dns_dbversion_t *version,
        dns_rdatatype_t type, unsigned int options, isc_stdtime_t now,
        dns_dbnode_t **nodep, dns_name_t *foundname,
        dns_clientinfomethods_t *methods, dns_clientinfo_t *clientinfo,
        dns_rdataset_t *rdataset, dns_rdataset_t *sigrdataset)
{
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        dns_dbnode_t *node = NULL;
        dns_fixedname_t fname;
        dns_rdataset_t xrdataset;
        dns_name_t *xname;
        unsigned int nlabels, olabels;
        isc_result_t result;
        unsigned int i;

        REQUIRE(VALID_SDLZDB(sdlz));
        REQUIRE(nodep == NULL || *nodep == NULL);
        REQUIRE(version == NULL ||
                version == (void*)&sdlz->dummy_version ||
                version == sdlz->future_version);

        UNUSED(sdlz);

        if (!dns_name_issubdomain(name, &db->origin))
                return (DNS_R_NXDOMAIN);

        olabels = dns_name_countlabels(&db->origin);
        nlabels = dns_name_countlabels(name);

        dns_fixedname_init(&fname);
        xname = dns_fixedname_name(&fname);

        if (rdataset == NULL) {
                dns_rdataset_init(&xrdataset);
                rdataset = &xrdataset;
        }

        result = DNS_R_NXDOMAIN;

        /*
         * If we're not walking down searching for zone
         * cuts, we can cut straight to the chase
         */
        if ((options & DNS_DBFIND_NOZONECUT) != 0) {
                i = nlabels;
                goto search;
        }

        for (i = olabels; i <= nlabels; i++) {
 search:
                /*
                 * Look up the next label.
                 */
                dns_name_getlabelsequence(name, nlabels - i, i, xname);
                result = getnodedata(db, xname, ISC_FALSE, options,
                                     methods, clientinfo, &node);
                if (result == ISC_R_NOTFOUND) {
                        result = DNS_R_NXDOMAIN;
                        continue;
                } else if (result != ISC_R_SUCCESS)
                        break;

                /*
                 * Look for a DNAME at the current label, unless this is
                 * the qname.
                 */
                if (i < nlabels) {
                        result = findrdataset(db, node, version,
                                              dns_rdatatype_dname, 0, now,
                                              rdataset, sigrdataset);
                        if (result == ISC_R_SUCCESS) {
                                result = DNS_R_DNAME;
                                break;
                        }
                }

                /*
                 * Look for an NS at the current label, unless this is the
                 * origin, glue is ok, or there are known to be no zone cuts.
                 */
                if (i != olabels && (options & DNS_DBFIND_GLUEOK) == 0 &&
                    (options & DNS_DBFIND_NOZONECUT) == 0)
                {
                        result = findrdataset(db, node, version,
                                              dns_rdatatype_ns, 0, now,
                                              rdataset, sigrdataset);

                        if (result == ISC_R_SUCCESS &&
                            i == nlabels && type == dns_rdatatype_any)
                        {
                                result = DNS_R_ZONECUT;
                                dns_rdataset_disassociate(rdataset);
                                if (sigrdataset != NULL &&
                                    dns_rdataset_isassociated(sigrdataset))
                                        dns_rdataset_disassociate(sigrdataset);
                                break;
                        } else if (result == ISC_R_SUCCESS) {
                                result = DNS_R_DELEGATION;
                                break;
                        }
                }

                /*
                 * If the current name is not the qname, add another label
                 * and try again.
                 */
                if (i < nlabels) {
                        destroynode(node);
                        node = NULL;
                        continue;
                }

                /*
                 * If we're looking for ANY, we're done.
                 */
                if (type == dns_rdatatype_any) {
                        result = ISC_R_SUCCESS;
                        break;
                }

                /*
                 * Look for the qtype.
                 */
                result = findrdataset(db, node, version, type, 0, now,
                                      rdataset, sigrdataset);
                if (result == ISC_R_SUCCESS)
                        break;

                /*
                 * Look for a CNAME
                 */
                if (type != dns_rdatatype_cname) {
                        result = findrdataset(db, node, version,
                                              dns_rdatatype_cname, 0, now,
                                              rdataset, sigrdataset);
                        if (result == ISC_R_SUCCESS) {
                                result = DNS_R_CNAME;
                                break;
                        }
                }

                result = DNS_R_NXRRSET;
                break;
        }

        if (rdataset == &xrdataset && dns_rdataset_isassociated(rdataset))
                dns_rdataset_disassociate(rdataset);

        if (foundname != NULL) {
                isc_result_t xresult;

                xresult = dns_name_copy(xname, foundname, NULL);
                if (xresult != ISC_R_SUCCESS) {
                        if (node != NULL)
                                destroynode(node);
                        if (dns_rdataset_isassociated(rdataset))
                                dns_rdataset_disassociate(rdataset);
                        return (DNS_R_BADDB);
                }
        }

        if (nodep != NULL)
                *nodep = node;
        else if (node != NULL)
                detachnode(db, &node);

        return (result);
}

static isc_result_t
find(dns_db_t *db, dns_name_t *name, dns_dbversion_t *version,
     dns_rdatatype_t type, unsigned int options, isc_stdtime_t now,
     dns_dbnode_t **nodep, dns_name_t *foundname,
     dns_rdataset_t *rdataset, dns_rdataset_t *sigrdataset)
{
        return (findext(db, name, version, type, options, now, nodep,
                        foundname, NULL, NULL, rdataset, sigrdataset));
}

static isc_result_t
allrdatasets(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
             isc_stdtime_t now, dns_rdatasetiter_t **iteratorp)
{
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *) db;
        sdlz_rdatasetiter_t *iterator;

        REQUIRE(VALID_SDLZDB(sdlz));

        REQUIRE(version == NULL ||
                version == (void*)&sdlz->dummy_version ||
                version == sdlz->future_version);

        UNUSED(version);
        UNUSED(now);

        iterator = isc_mem_get(db->mctx, sizeof(sdlz_rdatasetiter_t));
        if (iterator == NULL)
                return (ISC_R_NOMEMORY);

        iterator->common.magic = DNS_RDATASETITER_MAGIC;
        iterator->common.methods = &rdatasetiter_methods;
        iterator->common.db = db;
        iterator->common.node = NULL;
        attachnode(db, node, &iterator->common.node);
        iterator->common.version = version;
        iterator->common.now = now;

        *iteratorp = (dns_rdatasetiter_t *)iterator;

        return (ISC_R_SUCCESS);
}

static isc_result_t
modrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
            dns_rdataset_t *rdataset, unsigned int options,
            dns_sdlzmodrdataset_t mod_function)
{
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        dns_master_style_t *style = NULL;
        isc_result_t result;
        isc_buffer_t *buffer = NULL;
        isc_mem_t *mctx;
        dns_sdlznode_t *sdlznode;
        char *rdatastr = NULL;
        char name[DNS_NAME_MAXTEXT + 1];

        REQUIRE(VALID_SDLZDB(sdlz));

        if (mod_function == NULL)
                return (ISC_R_NOTIMPLEMENTED);

        sdlznode = (dns_sdlznode_t *)node;

        UNUSED(options);

        dns_name_format(sdlznode->name, name, sizeof(name));

        mctx = sdlz->common.mctx;

        result = isc_buffer_allocate(mctx, &buffer, 1024);
        if (result != ISC_R_SUCCESS)
                return (result);

        result = dns_master_stylecreate(&style, 0, 0, 0, 0, 0, 0, 1, mctx);
        if (result != ISC_R_SUCCESS)
                goto cleanup;

        result = dns_master_rdatasettotext(sdlznode->name, rdataset,
                                           style, buffer);
        if (result != ISC_R_SUCCESS)
                goto cleanup;

        if (isc_buffer_usedlength(buffer) < 1) {
                result = ISC_R_BADADDRESSFORM;
                goto cleanup;
        }

        rdatastr = isc_buffer_base(buffer);
        if (rdatastr == NULL) {
                result = ISC_R_NOMEMORY;
                goto cleanup;
        }
        rdatastr[isc_buffer_usedlength(buffer) - 1] = 0;

        MAYBE_LOCK(sdlz->dlzimp);
        result = mod_function(name, rdatastr, sdlz->dlzimp->driverarg,
                              sdlz->dbdata, version);
        MAYBE_UNLOCK(sdlz->dlzimp);

cleanup:
        isc_buffer_free(&buffer);
        if (style != NULL)
                dns_master_styledestroy(&style, mctx);

        return (result);
}

static isc_result_t
addrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
            isc_stdtime_t now, dns_rdataset_t *rdataset, unsigned int options,
            dns_rdataset_t *addedrdataset)
{
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        isc_result_t result;

        UNUSED(now);
        UNUSED(addedrdataset);
        REQUIRE(VALID_SDLZDB(sdlz));

        if (sdlz->dlzimp->methods->addrdataset == NULL)
                return (ISC_R_NOTIMPLEMENTED);

        result = modrdataset(db, node, version, rdataset, options,
                             sdlz->dlzimp->methods->addrdataset);
        return (result);
}


static isc_result_t
subtractrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
                 dns_rdataset_t *rdataset, unsigned int options,
                 dns_rdataset_t *newrdataset)
{
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        isc_result_t result;

        UNUSED(newrdataset);
        REQUIRE(VALID_SDLZDB(sdlz));

        if (sdlz->dlzimp->methods->subtractrdataset == NULL) {
                return (ISC_R_NOTIMPLEMENTED);
        }

        result = modrdataset(db, node, version, rdataset, options,
                             sdlz->dlzimp->methods->subtractrdataset);
        return (result);
}

static isc_result_t
deleterdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
               dns_rdatatype_t type, dns_rdatatype_t covers)
{
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        char name[DNS_NAME_MAXTEXT + 1];
        char b_type[DNS_RDATATYPE_FORMATSIZE];
        dns_sdlznode_t *sdlznode;
        isc_result_t result;

        UNUSED(covers);

        REQUIRE(VALID_SDLZDB(sdlz));

        if (sdlz->dlzimp->methods->delrdataset == NULL)
                return (ISC_R_NOTIMPLEMENTED);

        sdlznode = (dns_sdlznode_t *)node;
        dns_name_format(sdlznode->name, name, sizeof(name));
        dns_rdatatype_format(type, b_type, sizeof(b_type));

        MAYBE_LOCK(sdlz->dlzimp);
        result = sdlz->dlzimp->methods->delrdataset(name, b_type,
                                                    sdlz->dlzimp->driverarg,
                                                    sdlz->dbdata, version);
        MAYBE_UNLOCK(sdlz->dlzimp);

        return (result);
}

static isc_boolean_t
issecure(dns_db_t *db) {
        UNUSED(db);

        return (ISC_FALSE);
}

static unsigned int
nodecount(dns_db_t *db) {
        UNUSED(db);

        return (0);
}

static isc_boolean_t
ispersistent(dns_db_t *db) {
        UNUSED(db);
        return (ISC_TRUE);
}

static void
overmem(dns_db_t *db, isc_boolean_t over) {
        UNUSED(db);
        UNUSED(over);
}

static void
settask(dns_db_t *db, isc_task_t *task) {
        UNUSED(db);
        UNUSED(task);
}

/*
 * getoriginnode() is used by the update code to find the
 * dns_rdatatype_dnskey record for a zone
 */
static isc_result_t
getoriginnode(dns_db_t *db, dns_dbnode_t **nodep) {
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)db;
        isc_result_t result;

        REQUIRE(VALID_SDLZDB(sdlz));
        if (sdlz->dlzimp->methods->newversion == NULL)
                return (ISC_R_NOTIMPLEMENTED);

        result = getnodedata(db, &sdlz->common.origin, ISC_FALSE,
                             0, NULL, NULL, nodep);
        if (result != ISC_R_SUCCESS)
                sdlz_log(ISC_LOG_ERROR, "sdlz getoriginnode failed: %s",
                         isc_result_totext(result));
        return (result);
}

static dns_dbmethods_t sdlzdb_methods = {
        attach,
        detach,
        beginload,
        endload,
        NULL,
        dump,
        currentversion,
        newversion,
        attachversion,
        closeversion,
        findnode,
        find,
        findzonecut,
        attachnode,
        detachnode,
        expirenode,
        printnode,
        createiterator,
        findrdataset,
        allrdatasets,
        addrdataset,
        subtractrdataset,
        deleterdataset,
        issecure,
        nodecount,
        ispersistent,
        overmem,
        settask,
        getoriginnode,
        NULL,                   /* transfernode */
        NULL,                   /* getnsec3parameters */
        NULL,                   /* findnsec3node */
        NULL,                   /* setsigningtime */
        NULL,                   /* getsigningtime */
        NULL,                   /* resigned */
        NULL,                   /* isdnssec */
        NULL,                   /* getrrsetstats */
        NULL,                   /* rpz_attach */
        NULL,                   /* rpz_ready */
        findnodeext,
        findext,
        NULL,                   /* setcachestats */
        NULL                    /* hashsize */
};

/*
 * Database Iterator Methods.  These methods were "borrowed" from the SDB
 * driver interface.  See the SDB driver interface documentation for more info.
 */

static void
dbiterator_destroy(dns_dbiterator_t **iteratorp) {
        sdlz_dbiterator_t *sdlziter = (sdlz_dbiterator_t *)(*iteratorp);
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)sdlziter->common.db;

        while (!ISC_LIST_EMPTY(sdlziter->nodelist)) {
                dns_sdlznode_t *node;
                node = ISC_LIST_HEAD(sdlziter->nodelist);
                ISC_LIST_UNLINK(sdlziter->nodelist, node, link);
                destroynode(node);
        }

        dns_db_detach(&sdlziter->common.db);
        isc_mem_put(sdlz->common.mctx, sdlziter, sizeof(sdlz_dbiterator_t));

        *iteratorp = NULL;
}

static isc_result_t
dbiterator_first(dns_dbiterator_t *iterator) {
        sdlz_dbiterator_t *sdlziter = (sdlz_dbiterator_t *)iterator;

        sdlziter->current = ISC_LIST_HEAD(sdlziter->nodelist);
        if (sdlziter->current == NULL)
                return (ISC_R_NOMORE);
        else
                return (ISC_R_SUCCESS);
}

static isc_result_t
dbiterator_last(dns_dbiterator_t *iterator) {
        sdlz_dbiterator_t *sdlziter = (sdlz_dbiterator_t *)iterator;

        sdlziter->current = ISC_LIST_TAIL(sdlziter->nodelist);
        if (sdlziter->current == NULL)
                return (ISC_R_NOMORE);
        else
                return (ISC_R_SUCCESS);
}

static isc_result_t
dbiterator_seek(dns_dbiterator_t *iterator, dns_name_t *name) {
        sdlz_dbiterator_t *sdlziter = (sdlz_dbiterator_t *)iterator;

        sdlziter->current = ISC_LIST_HEAD(sdlziter->nodelist);
        while (sdlziter->current != NULL) {
                if (dns_name_equal(sdlziter->current->name, name))
                        return (ISC_R_SUCCESS);
                sdlziter->current = ISC_LIST_NEXT(sdlziter->current, link);
        }
        return (ISC_R_NOTFOUND);
}

static isc_result_t
dbiterator_prev(dns_dbiterator_t *iterator) {
        sdlz_dbiterator_t *sdlziter = (sdlz_dbiterator_t *)iterator;

        sdlziter->current = ISC_LIST_PREV(sdlziter->current, link);
        if (sdlziter->current == NULL)
                return (ISC_R_NOMORE);
        else
                return (ISC_R_SUCCESS);
}

static isc_result_t
dbiterator_next(dns_dbiterator_t *iterator) {
        sdlz_dbiterator_t *sdlziter = (sdlz_dbiterator_t *)iterator;

        sdlziter->current = ISC_LIST_NEXT(sdlziter->current, link);
        if (sdlziter->current == NULL)
                return (ISC_R_NOMORE);
        else
                return (ISC_R_SUCCESS);
}

static isc_result_t
dbiterator_current(dns_dbiterator_t *iterator, dns_dbnode_t **nodep,
                   dns_name_t *name)
{
        sdlz_dbiterator_t *sdlziter = (sdlz_dbiterator_t *)iterator;

        attachnode(iterator->db, sdlziter->current, nodep);
        if (name != NULL)
                return (dns_name_copy(sdlziter->current->name, name, NULL));
        return (ISC_R_SUCCESS);
}

static isc_result_t
dbiterator_pause(dns_dbiterator_t *iterator) {
        UNUSED(iterator);
        return (ISC_R_SUCCESS);
}

static isc_result_t
dbiterator_origin(dns_dbiterator_t *iterator, dns_name_t *name) {
        UNUSED(iterator);
        return (dns_name_copy(dns_rootname, name, NULL));
}

/*
 * Rdataset Methods. These methods were "borrowed" from the SDB driver
 * interface.  See the SDB driver interface documentation for more info.
 */

static void
disassociate(dns_rdataset_t *rdataset) {
        dns_dbnode_t *node = rdataset->private5;
        dns_sdlznode_t *sdlznode = (dns_sdlznode_t *) node;
        dns_db_t *db = (dns_db_t *) sdlznode->sdlz;

        detachnode(db, &node);
        isc__rdatalist_disassociate(rdataset);
}

static void
rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
        dns_dbnode_t *node = source->private5;
        dns_sdlznode_t *sdlznode = (dns_sdlznode_t *) node;
        dns_db_t *db = (dns_db_t *) sdlznode->sdlz;
        dns_dbnode_t *tempdb = NULL;

        isc__rdatalist_clone(source, target);
        attachnode(db, node, &tempdb);
        source->private5 = tempdb;
}

static dns_rdatasetmethods_t rdataset_methods = {
        disassociate,
        isc__rdatalist_first,
        isc__rdatalist_next,
        isc__rdatalist_current,
        rdataset_clone,
        isc__rdatalist_count,
        isc__rdatalist_addnoqname,
        isc__rdatalist_getnoqname,
        NULL,
        NULL,
        NULL,
        NULL,
        NULL,
        NULL,
        NULL,
        NULL,
        NULL,
        NULL
};

static void
list_tordataset(dns_rdatalist_t *rdatalist,
                dns_db_t *db, dns_dbnode_t *node,
                dns_rdataset_t *rdataset)
{
        /*
         * The sdlz rdataset is an rdatalist with some additions.
         *      - private1 & private2 are used by the rdatalist.
         *      - private3 & private 4 are unused.
         *      - private5 is the node.
         */

        /* This should never fail. */
        RUNTIME_CHECK(dns_rdatalist_tordataset(rdatalist, rdataset) ==
                      ISC_R_SUCCESS);

        rdataset->methods = &rdataset_methods;
        dns_db_attachnode(db, node, &rdataset->private5);
}

/*
 * SDLZ core methods. This is the core of the new DLZ functionality.
 */

/*%
 * Build a 'bind' database driver structure to be returned by
 * either the find zone or the allow zone transfer method.
 * This method is only available in this source file, it is
 * not made available anywhere else.
 */

static isc_result_t
dns_sdlzcreateDBP(isc_mem_t *mctx, void *driverarg, void *dbdata,
                  dns_name_t *name, dns_rdataclass_t rdclass, dns_db_t **dbp)
{
        isc_result_t result;
        dns_sdlz_db_t *sdlzdb;
        dns_sdlzimplementation_t *imp;

        /* check that things are as we expect */
        REQUIRE(dbp != NULL && *dbp == NULL);
        REQUIRE(name != NULL);

        imp = (dns_sdlzimplementation_t *) driverarg;

        /* allocate and zero memory for driver structure */
        sdlzdb = isc_mem_get(mctx, sizeof(dns_sdlz_db_t));
        if (sdlzdb == NULL)
                return (ISC_R_NOMEMORY);
        memset(sdlzdb, 0, sizeof(dns_sdlz_db_t));

        /* initialize and set origin */
        dns_name_init(&sdlzdb->common.origin, NULL);
        result = dns_name_dupwithoffsets(name, mctx, &sdlzdb->common.origin);
        if (result != ISC_R_SUCCESS)
                goto mem_cleanup;

        /* initialize the reference count mutex */
        result = isc_mutex_init(&sdlzdb->refcnt_lock);
        if (result != ISC_R_SUCCESS)
                goto name_cleanup;

        /* set the rest of the database structure attributes */
        sdlzdb->dlzimp = imp;
        sdlzdb->common.methods = &sdlzdb_methods;
        sdlzdb->common.attributes = 0;
        sdlzdb->common.rdclass = rdclass;
        sdlzdb->common.mctx = NULL;
        sdlzdb->dbdata = dbdata;
        sdlzdb->references = 1;

        /* attach to the memory context */
        isc_mem_attach(mctx, &sdlzdb->common.mctx);

        /* mark structure as valid */
        sdlzdb->common.magic = DNS_DB_MAGIC;
        sdlzdb->common.impmagic = SDLZDB_MAGIC;
        *dbp = (dns_db_t *) sdlzdb;

        return (result);

        /*
         * reference count mutex could not be initialized, clean up
         * name memory
         */
 name_cleanup:
        dns_name_free(&sdlzdb->common.origin, mctx);
 mem_cleanup:
        isc_mem_put(mctx, sdlzdb, sizeof(dns_sdlz_db_t));
        return (result);
}

static isc_result_t
dns_sdlzallowzonexfr(void *driverarg, void *dbdata, isc_mem_t *mctx,
                     dns_rdataclass_t rdclass, dns_name_t *name,
                     isc_sockaddr_t *clientaddr, dns_db_t **dbp)
{
        isc_buffer_t b;
        isc_buffer_t b2;
        char namestr[DNS_NAME_MAXTEXT + 1];
        char clientstr[(sizeof "xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255")
                       + 1];
        isc_netaddr_t netaddr;
        isc_result_t result;
        dns_sdlzimplementation_t *imp;

        /*
         * Perform checks to make sure data is as we expect it to be.
         */
        REQUIRE(driverarg != NULL);
        REQUIRE(name != NULL);
        REQUIRE(clientaddr != NULL);
        REQUIRE(dbp != NULL && *dbp == NULL);

        imp = (dns_sdlzimplementation_t *) driverarg;

        /* Convert DNS name to ascii text */
        isc_buffer_init(&b, namestr, sizeof(namestr));
        result = dns_name_totext(name, ISC_TRUE, &b);
        if (result != ISC_R_SUCCESS)
                return (result);
        isc_buffer_putuint8(&b, 0);

        /* convert client address to ascii text */
        isc_buffer_init(&b2, clientstr, sizeof(clientstr));
        isc_netaddr_fromsockaddr(&netaddr, clientaddr);
        result = isc_netaddr_totext(&netaddr, &b2);
        if (result != ISC_R_SUCCESS)
                return (result);
        isc_buffer_putuint8(&b2, 0);

        /* make sure strings are always lowercase */
        dns_sdlz_tolower(namestr);
        dns_sdlz_tolower(clientstr);

        /* Call SDLZ driver's find zone method */
        if (imp->methods->allowzonexfr != NULL) {
                MAYBE_LOCK(imp);
                result = imp->methods->allowzonexfr(imp->driverarg, dbdata,
                                                    namestr, clientstr);
                MAYBE_UNLOCK(imp);
                /*
                 * if zone is supported and transfers allowed build a 'bind'
                 * database driver
                 */
                if (result == ISC_R_SUCCESS)
                        result = dns_sdlzcreateDBP(mctx, driverarg, dbdata,
                                                   name, rdclass, dbp);
                return (result);
        }

        return (ISC_R_NOTIMPLEMENTED);
}

static isc_result_t
dns_sdlzcreate(isc_mem_t *mctx, const char *dlzname, unsigned int argc,
               char *argv[], void *driverarg, void **dbdata)
{
        dns_sdlzimplementation_t *imp;
        isc_result_t result = ISC_R_NOTFOUND;

        /* Write debugging message to log */
        sdlz_log(ISC_LOG_DEBUG(2), "Loading SDLZ driver.");

        /*
         * Performs checks to make sure data is as we expect it to be.
         */
        REQUIRE(driverarg != NULL);
        REQUIRE(dlzname != NULL);
        REQUIRE(dbdata != NULL);
        UNUSED(mctx);

        imp = driverarg;

        /* If the create method exists, call it. */
        if (imp->methods->create != NULL) {
                MAYBE_LOCK(imp);
                result = imp->methods->create(dlzname, argc, argv,
                                              imp->driverarg, dbdata);
                MAYBE_UNLOCK(imp);
        }

        /* Write debugging message to log */
        if (result == ISC_R_SUCCESS) {
                sdlz_log(ISC_LOG_DEBUG(2), "SDLZ driver loaded successfully.");
        } else {
                sdlz_log(ISC_LOG_ERROR, "SDLZ driver failed to load.");
        }

        return (result);
}

static void
dns_sdlzdestroy(void *driverdata, void **dbdata) {
        dns_sdlzimplementation_t *imp;

        /* Write debugging message to log */
        sdlz_log(ISC_LOG_DEBUG(2), "Unloading SDLZ driver.");

        imp = driverdata;

        /* If the destroy method exists, call it. */
        if (imp->methods->destroy != NULL) {
                MAYBE_LOCK(imp);
                imp->methods->destroy(imp->driverarg, dbdata);
                MAYBE_UNLOCK(imp);
        }
}

static isc_result_t
dns_sdlzfindzone(void *driverarg, void *dbdata, isc_mem_t *mctx,
                 dns_rdataclass_t rdclass, dns_name_t *name,
                 dns_clientinfomethods_t *methods,
                 dns_clientinfo_t *clientinfo,
                 dns_db_t **dbp)
{
        isc_buffer_t b;
        char namestr[DNS_NAME_MAXTEXT + 1];
        isc_result_t result;
        dns_sdlzimplementation_t *imp;

        /*
         * Perform checks to make sure data is as we expect it to be.
         */
        REQUIRE(driverarg != NULL);
        REQUIRE(name != NULL);
        REQUIRE(dbp != NULL && *dbp == NULL);

        imp = (dns_sdlzimplementation_t *) driverarg;

        /* Convert DNS name to ascii text */
        isc_buffer_init(&b, namestr, sizeof(namestr));
        result = dns_name_totext(name, ISC_TRUE, &b);
        if (result != ISC_R_SUCCESS)
                return (result);
        isc_buffer_putuint8(&b, 0);

        /* make sure strings are always lowercase */
        dns_sdlz_tolower(namestr);

        /* Call SDLZ driver's find zone method */
        MAYBE_LOCK(imp);
        result = imp->methods->findzone(imp->driverarg, dbdata, namestr,
                                        methods, clientinfo);
        MAYBE_UNLOCK(imp);

        /*
         * if zone is supported build a 'bind' database driver
         * structure to return
         */
        if (result == ISC_R_SUCCESS)
                result = dns_sdlzcreateDBP(mctx, driverarg, dbdata, name,
                                           rdclass, dbp);

        return (result);
}


static isc_result_t
dns_sdlzconfigure(void *driverarg, void *dbdata,
                  dns_view_t *view, dns_dlzdb_t *dlzdb)
{
        isc_result_t result;
        dns_sdlzimplementation_t *imp;

        REQUIRE(driverarg != NULL);

        imp = (dns_sdlzimplementation_t *) driverarg;

        /* Call SDLZ driver's configure method */
        if (imp->methods->configure != NULL) {
                MAYBE_LOCK(imp);
                result = imp->methods->configure(view, dlzdb,
                                                 imp->driverarg, dbdata);
                MAYBE_UNLOCK(imp);
        } else {
                result = ISC_R_SUCCESS;
        }

        return (result);
}

static isc_boolean_t
dns_sdlzssumatch(dns_name_t *signer, dns_name_t *name, isc_netaddr_t *tcpaddr,
                 dns_rdatatype_t type, const dst_key_t *key, void *driverarg,
                 void *dbdata)
{
        dns_sdlzimplementation_t *imp;
        char b_signer[DNS_NAME_FORMATSIZE];
        char b_name[DNS_NAME_FORMATSIZE];
        char b_addr[ISC_NETADDR_FORMATSIZE];
        char b_type[DNS_RDATATYPE_FORMATSIZE];
        char b_key[DST_KEY_FORMATSIZE];
        isc_buffer_t *tkey_token = NULL;
        isc_region_t token_region;
        isc_uint32_t token_len = 0;
        isc_boolean_t ret;

        REQUIRE(driverarg != NULL);

        imp = (dns_sdlzimplementation_t *) driverarg;
        if (imp->methods->ssumatch == NULL)
                return (ISC_FALSE);

        /*
         * Format the request elements. sdlz operates on strings, not
         * structures
         */
        if (signer != NULL)
                dns_name_format(signer, b_signer, sizeof(b_signer));
        else
                b_signer[0] = 0;

        dns_name_format(name, b_name, sizeof(b_name));

        if (tcpaddr != NULL)
                isc_netaddr_format(tcpaddr, b_addr, sizeof(b_addr));
        else
                b_addr[0] = 0;

        dns_rdatatype_format(type, b_type, sizeof(b_type));

        if (key != NULL) {
                dst_key_format(key, b_key, sizeof(b_key));
                tkey_token = dst_key_tkeytoken(key);
        } else
                b_key[0] = 0;

        if (tkey_token != NULL) {
                isc_buffer_region(tkey_token, &token_region);
                token_len = token_region.length;
        }

        MAYBE_LOCK(imp);
        ret = imp->methods->ssumatch(b_signer, b_name, b_addr, b_type, b_key,
                                     token_len,
                                     token_len != 0 ? token_region.base : NULL,
                                     imp->driverarg, dbdata);
        MAYBE_UNLOCK(imp);
        return (ret);
}

static dns_dlzmethods_t sdlzmethods = {
        dns_sdlzcreate,
        dns_sdlzdestroy,
        dns_sdlzfindzone,
        dns_sdlzallowzonexfr,
        dns_sdlzconfigure,
        dns_sdlzssumatch
};

/*
 * Public functions.
 */

isc_result_t
dns_sdlz_putrr(dns_sdlzlookup_t *lookup, const char *type, dns_ttl_t ttl,
               const char *data)
{
        dns_rdatalist_t *rdatalist;
        dns_rdata_t *rdata;
        dns_rdatatype_t typeval;
        isc_consttextregion_t r;
        isc_buffer_t b;
        isc_buffer_t *rdatabuf = NULL;
        isc_lex_t *lex;
        isc_result_t result;
        unsigned int size;
        isc_mem_t *mctx;
        dns_name_t *origin;

        REQUIRE(VALID_SDLZLOOKUP(lookup));
        REQUIRE(type != NULL);
        REQUIRE(data != NULL);

        mctx = lookup->sdlz->common.mctx;

        r.base = type;
        r.length = strlen(type);
        result = dns_rdatatype_fromtext(&typeval, (void *) &r);
        if (result != ISC_R_SUCCESS)
                return (result);

        rdatalist = ISC_LIST_HEAD(lookup->lists);
        while (rdatalist != NULL) {
                if (rdatalist->type == typeval)
                        break;
                rdatalist = ISC_LIST_NEXT(rdatalist, link);
        }

        if (rdatalist == NULL) {
                rdatalist = isc_mem_get(mctx, sizeof(dns_rdatalist_t));
                if (rdatalist == NULL)
                        return (ISC_R_NOMEMORY);
                dns_rdatalist_init(rdatalist);
                rdatalist->rdclass = lookup->sdlz->common.rdclass;
                rdatalist->type = typeval;
                rdatalist->ttl = ttl;
                ISC_LIST_APPEND(lookup->lists, rdatalist, link);
        } else
                if (rdatalist->ttl > ttl) {
                        /*
                         * BIND9 doesn't enforce all RRs in an RRset
                         * having the same TTL, as per RFC 2136,
                         * section 7.12. If a DLZ backend has
                         * different TTLs, then the best
                         * we can do is return the lowest.
                        */
                        rdatalist->ttl = ttl;
                }

        rdata = isc_mem_get(mctx, sizeof(dns_rdata_t));
        if (rdata == NULL)
                return (ISC_R_NOMEMORY);
        dns_rdata_init(rdata);

        if ((lookup->sdlz->dlzimp->flags & DNS_SDLZFLAG_RELATIVERDATA) != 0)
                origin = &lookup->sdlz->common.origin;
        else
                origin = dns_rootname;

        lex = NULL;
        result = isc_lex_create(mctx, 64, &lex);
        if (result != ISC_R_SUCCESS)
                goto failure;

        size = initial_size(data);
        do {
                isc_buffer_constinit(&b, data, strlen(data));
                isc_buffer_add(&b, strlen(data));

                result = isc_lex_openbuffer(lex, &b);
                if (result != ISC_R_SUCCESS)
                        goto failure;

                rdatabuf = NULL;
                result = isc_buffer_allocate(mctx, &rdatabuf, size);
                if (result != ISC_R_SUCCESS)
                        goto failure;

                result = dns_rdata_fromtext(rdata, rdatalist->rdclass,
                                            rdatalist->type, lex,
                                            origin, ISC_FALSE,
                                            mctx, rdatabuf,
                                            &lookup->callbacks);
                if (result != ISC_R_SUCCESS)
                        isc_buffer_free(&rdatabuf);
                if (size >= 65535)
                        break;
                size *= 2;
                if (size >= 65535)
                        size = 65535;
        } while (result == ISC_R_NOSPACE);

        if (result != ISC_R_SUCCESS)
                goto failure;

        ISC_LIST_APPEND(rdatalist->rdata, rdata, link);
        ISC_LIST_APPEND(lookup->buffers, rdatabuf, link);

        if (lex != NULL)
                isc_lex_destroy(&lex);

        return (ISC_R_SUCCESS);

 failure:
        if (rdatabuf != NULL)
                isc_buffer_free(&rdatabuf);
        if (lex != NULL)
                isc_lex_destroy(&lex);
        isc_mem_put(mctx, rdata, sizeof(dns_rdata_t));

        return (result);
}

isc_result_t
dns_sdlz_putnamedrr(dns_sdlzallnodes_t *allnodes, const char *name,
                    const char *type, dns_ttl_t ttl, const char *data)
{
        dns_name_t *newname, *origin;
        dns_fixedname_t fnewname;
        dns_sdlz_db_t *sdlz = (dns_sdlz_db_t *)allnodes->common.db;
        dns_sdlznode_t *sdlznode;
        isc_mem_t *mctx = sdlz->common.mctx;
        isc_buffer_t b;
        isc_result_t result;

        dns_fixedname_init(&fnewname);
        newname = dns_fixedname_name(&fnewname);

        if ((sdlz->dlzimp->flags & DNS_SDLZFLAG_RELATIVERDATA) != 0)
                origin = &sdlz->common.origin;
        else
                origin = dns_rootname;
        isc_buffer_constinit(&b, name, strlen(name));
        isc_buffer_add(&b, strlen(name));

        result = dns_name_fromtext(newname, &b, origin, 0, NULL);
        if (result != ISC_R_SUCCESS)
                return (result);

        if (allnodes->common.relative_names) {
                /* All names are relative to the root */
                unsigned int nlabels = dns_name_countlabels(newname);
                dns_name_getlabelsequence(newname, 0, nlabels - 1, newname);
        }

        sdlznode = ISC_LIST_HEAD(allnodes->nodelist);
        if (sdlznode == NULL || !dns_name_equal(sdlznode->name, newname)) {
                sdlznode = NULL;
                result = createnode(sdlz, &sdlznode);
                if (result != ISC_R_SUCCESS)
                        return (result);
                sdlznode->name = isc_mem_get(mctx, sizeof(dns_name_t));
                if (sdlznode->name == NULL) {
                        destroynode(sdlznode);
                        return (ISC_R_NOMEMORY);
                }
                dns_name_init(sdlznode->name, NULL);
                result = dns_name_dup(newname, mctx, sdlznode->name);
                if (result != ISC_R_SUCCESS) {
                        isc_mem_put(mctx, sdlznode->name, sizeof(dns_name_t));
                        destroynode(sdlznode);
                        return (result);
                }
                ISC_LIST_PREPEND(allnodes->nodelist, sdlznode, link);
                if (allnodes->origin == NULL &&
                    dns_name_equal(newname, &sdlz->common.origin))
                        allnodes->origin = sdlznode;
        }
        return (dns_sdlz_putrr(sdlznode, type, ttl, data));

}

isc_result_t
dns_sdlz_putsoa(dns_sdlzlookup_t *lookup, const char *mname, const char *rname,
                isc_uint32_t serial)
{
        char str[2 * DNS_NAME_MAXTEXT + 5 * (sizeof("2147483647")) + 7];
        int n;

        REQUIRE(mname != NULL);
        REQUIRE(rname != NULL);

        n = snprintf(str, sizeof str, "%s %s %u %u %u %u %u",
                     mname, rname, serial,
                     SDLZ_DEFAULT_REFRESH, SDLZ_DEFAULT_RETRY,
                     SDLZ_DEFAULT_EXPIRE, SDLZ_DEFAULT_MINIMUM);
        if (n >= (int)sizeof(str) || n < 0)
                return (ISC_R_NOSPACE);
        return (dns_sdlz_putrr(lookup, "SOA", SDLZ_DEFAULT_TTL, str));
}

isc_result_t
dns_sdlzregister(const char *drivername, const dns_sdlzmethods_t *methods,
                 void *driverarg, unsigned int flags, isc_mem_t *mctx,
                 dns_sdlzimplementation_t **sdlzimp)
{

        dns_sdlzimplementation_t *imp;
        isc_result_t result;

        /*
         * Performs checks to make sure data is as we expect it to be.
         */
        REQUIRE(drivername != NULL);
        REQUIRE(methods != NULL);
        REQUIRE(methods->findzone != NULL);
        REQUIRE(methods->lookup != NULL);
        REQUIRE(mctx != NULL);
        REQUIRE(sdlzimp != NULL && *sdlzimp == NULL);
        REQUIRE((flags & ~(DNS_SDLZFLAG_RELATIVEOWNER |
                           DNS_SDLZFLAG_RELATIVERDATA |
                           DNS_SDLZFLAG_THREADSAFE)) == 0);

        /* Write debugging message to log */
        sdlz_log(ISC_LOG_DEBUG(2), "Registering SDLZ driver '%s'", drivername);

        /*
         * Allocate memory for a sdlz_implementation object.  Error if
         * we cannot.
         */
        imp = isc_mem_get(mctx, sizeof(dns_sdlzimplementation_t));
        if (imp == NULL)
                return (ISC_R_NOMEMORY);

        /* Make sure memory region is set to all 0's */
        memset(imp, 0, sizeof(dns_sdlzimplementation_t));

        /* Store the data passed into this method */
        imp->methods = methods;
        imp->driverarg = driverarg;
        imp->flags = flags;
        imp->mctx = NULL;

        /* attach the new sdlz_implementation object to a memory context */
        isc_mem_attach(mctx, &imp->mctx);

        /*
         * initialize the driver lock, error if we cannot
         * (used if a driver does not support multiple threads)
         */
        result = isc_mutex_init(&imp->driverlock);
        if (result != ISC_R_SUCCESS) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "isc_mutex_init() failed: %s",
                                 isc_result_totext(result));
                goto cleanup_mctx;
        }

        imp->dlz_imp = NULL;

        /*
         * register the DLZ driver.  Pass in our "extra" sdlz information as
         * a driverarg.  (that's why we stored the passed in driver arg in our
         * sdlz_implementation structure)  Also, store the dlz_implementation
         * structure in our sdlz_implementation.
         */
        result = dns_dlzregister(drivername, &sdlzmethods, imp, mctx,
                                 &imp->dlz_imp);

        /* if registration fails, cleanup and get outta here. */
        if (result != ISC_R_SUCCESS)
                goto cleanup_mutex;

        *sdlzimp = imp;

        return (ISC_R_SUCCESS);

 cleanup_mutex:
        /* destroy the driver lock, we don't need it anymore */
        DESTROYLOCK(&imp->driverlock);

 cleanup_mctx:
        /*
         * return the memory back to the available memory pool and
         * remove it from the memory context.
         */
        isc_mem_put(mctx, imp, sizeof(dns_sdlzimplementation_t));
        isc_mem_detach(&mctx);
        return (result);
}

void
dns_sdlzunregister(dns_sdlzimplementation_t **sdlzimp) {
        dns_sdlzimplementation_t *imp;
        isc_mem_t *mctx;

        /* Write debugging message to log */
        sdlz_log(ISC_LOG_DEBUG(2), "Unregistering SDLZ driver.");

        /*
         * Performs checks to make sure data is as we expect it to be.
         */
        REQUIRE(sdlzimp != NULL && *sdlzimp != NULL);

        imp = *sdlzimp;

        /* Unregister the DLZ driver implementation */
        dns_dlzunregister(&imp->dlz_imp);

        /* destroy the driver lock, we don't need it anymore */
        DESTROYLOCK(&imp->driverlock);

        mctx = imp->mctx;

        /*
         * return the memory back to the available memory pool and
         * remove it from the memory context.
         */
        isc_mem_put(mctx, imp, sizeof(dns_sdlzimplementation_t));
        isc_mem_detach(&mctx);

        *sdlzimp = NULL;
}


isc_result_t
dns_sdlz_setdb(dns_dlzdb_t *dlzdatabase, dns_rdataclass_t rdclass,
               dns_name_t *name, dns_db_t **dbp)
{
        isc_result_t result;

        result = dns_sdlzcreateDBP(dlzdatabase->mctx,
                                   dlzdatabase->implementation->driverarg,
                                   dlzdatabase->dbdata, name, rdclass, dbp);
        return (result);
}

---