lib/dns/sdlz.c

/*
 * Portions Copyright (C) 1999-2001, 2005-2017  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/*
 * 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 */
    NULL,           /* nodefullname */
    NULL            /* getsize */
};

/*
 * 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 = { NULL, 0 };
    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);
}