lib/dns/ecdb.c

	ecdb.c revision 5e93bad21b6d68fce862ff8aace3bb29b658f4f6
/*
 * Copyright (C) 2009-2015  Internet Systems Consortium, Inc. ("ISC")
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#include "config.h"

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

#include <dns/db.h>
#include <dns/ecdb.h>
#include <dns/rdata.h>
#include <dns/rdataset.h>
#include <dns/rdatasetiter.h>
#include <dns/rdataslab.h>

#define ECDB_MAGIC      ISC_MAGIC('E', 'C', 'D', 'B')
#define VALID_ECDB(db)      ((db) != NULL && \
                 (db)->common.impmagic == ECDB_MAGIC)

#define ECDBNODE_MAGIC      ISC_MAGIC('E', 'C', 'D', 'N')
#define VALID_ECDBNODE(ecdbn)   ISC_MAGIC_VALID(ecdbn, ECDBNODE_MAGIC)

/*%
 * The 'ephemeral' cache DB (ecdb) implementation.  An ecdb just provides
 * temporary storage for ongoing name resolution with the common DB interfaces.
 * It actually doesn't cache anything.  The implementation expects any stored
 * data is released within a short period, and does not care about the
 * scalability in terms of the number of nodes.
 */

typedef struct dns_ecdb {
    /* Unlocked */
    dns_db_t            common;
    isc_mutex_t         lock;

    /* Locked */
    unsigned int            references;
    ISC_LIST(struct dns_ecdbnode)   nodes;
} dns_ecdb_t;

typedef struct dns_ecdbnode {
    /* Unlocked */
    unsigned int            magic;
    isc_mutex_t         lock;
    dns_ecdb_t          *ecdb;
    dns_name_t          name;
    ISC_LINK(struct dns_ecdbnode)   link;

    /* Locked */
    ISC_LIST(struct rdatasetheader) rdatasets;
    unsigned int            references;
} dns_ecdbnode_t;

typedef struct rdatasetheader {
    dns_rdatatype_t         type;
    dns_ttl_t           ttl;
    dns_trust_t         trust;
    dns_rdatatype_t         covers;
    unsigned int            attributes;

    ISC_LINK(struct rdatasetheader) link;
} rdatasetheader_t;

/* Copied from rbtdb.c */
#define RDATASET_ATTR_NXDOMAIN      0x0010
#define RDATASET_ATTR_NEGATIVE      0x0100
#define NXDOMAIN(header) \
    (((header)->attributes & RDATASET_ATTR_NXDOMAIN) != 0)
#define NEGATIVE(header) \
    (((header)->attributes & RDATASET_ATTR_NEGATIVE) != 0)

static isc_result_t dns_ecdb_create(isc_mem_t *mctx, dns_name_t *origin,
                    dns_dbtype_t type,
                    dns_rdataclass_t rdclass,
                    unsigned int argc, char *argv[],
                    void *driverarg, dns_db_t **dbp);

static void rdataset_disassociate(dns_rdataset_t *rdataset);
static isc_result_t rdataset_first(dns_rdataset_t *rdataset);
static isc_result_t rdataset_next(dns_rdataset_t *rdataset);
static void rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata);
static void rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target);
static unsigned int rdataset_count(dns_rdataset_t *rdataset);
static void rdataset_settrust(dns_rdataset_t *rdataset, dns_trust_t trust);

static dns_rdatasetmethods_t rdataset_methods = {
    rdataset_disassociate,
    rdataset_first,
    rdataset_next,
    rdataset_current,
    rdataset_clone,
    rdataset_count,
    NULL,           /* addnoqname */
    NULL,           /* getnoqname */
    NULL,           /* addclosest */
    NULL,           /* getclosest */
    NULL,           /* getadditional */
    NULL,           /* setadditional */
    NULL,           /* putadditional */
    rdataset_settrust,  /* settrust */
    NULL,           /* expire */
    NULL,           /* clearprefetch */
    NULL,           /* setownercase */
    NULL            /* getownercase */
};

typedef struct ecdb_rdatasetiter {
    dns_rdatasetiter_t      common;
    rdatasetheader_t           *current;
} ecdb_rdatasetiter_t;

static void     rdatasetiter_destroy(dns_rdatasetiter_t **iteratorp);
static isc_result_t rdatasetiter_first(dns_rdatasetiter_t *iterator);
static isc_result_t rdatasetiter_next(dns_rdatasetiter_t *iterator);
static void     rdatasetiter_current(dns_rdatasetiter_t *iterator,
                         dns_rdataset_t *rdataset);

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

isc_result_t
dns_ecdb_register(isc_mem_t *mctx, dns_dbimplementation_t **dbimp) {
    REQUIRE(mctx != NULL);
    REQUIRE(dbimp != NULL && *dbimp == NULL);

    return (dns_db_register("ecdb", dns_ecdb_create, NULL, mctx, dbimp));
}

void
dns_ecdb_unregister(dns_dbimplementation_t **dbimp) {
    REQUIRE(dbimp != NULL && *dbimp != NULL);

    dns_db_unregister(dbimp);
}

/*%
 * DB routines
 */

static void
attach(dns_db_t *source, dns_db_t **targetp) {
    dns_ecdb_t *ecdb = (dns_ecdb_t *)source;

    REQUIRE(VALID_ECDB(ecdb));
    REQUIRE(targetp != NULL && *targetp == NULL);

    LOCK(&ecdb->lock);
    ecdb->references++;
    UNLOCK(&ecdb->lock);

    *targetp = source;
}

static void
destroy_ecdb(dns_ecdb_t **ecdbp) {
    dns_ecdb_t *ecdb = *ecdbp;
    isc_mem_t *mctx = ecdb->common.mctx;

    if (dns_name_dynamic(&ecdb->common.origin))
        dns_name_free(&ecdb->common.origin, mctx);

    DESTROYLOCK(&ecdb->lock);

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

    isc_mem_putanddetach(&mctx, ecdb, sizeof(*ecdb));

    *ecdbp = NULL;
}

static void
detach(dns_db_t **dbp) {
    dns_ecdb_t *ecdb;
    isc_boolean_t need_destroy = ISC_FALSE;

    REQUIRE(dbp != NULL);
    ecdb = (dns_ecdb_t *)*dbp;
    REQUIRE(VALID_ECDB(ecdb));

    LOCK(&ecdb->lock);
    ecdb->references--;
    if (ecdb->references == 0 && ISC_LIST_EMPTY(ecdb->nodes))
        need_destroy = ISC_TRUE;
    UNLOCK(&ecdb->lock);

    if (need_destroy)
        destroy_ecdb(&ecdb);

    *dbp = NULL;
}

static void
attachnode(dns_db_t *db, dns_dbnode_t *source, dns_dbnode_t **targetp) {
    dns_ecdb_t *ecdb = (dns_ecdb_t *)db;
    dns_ecdbnode_t *node = (dns_ecdbnode_t *)source;

    REQUIRE(VALID_ECDB(ecdb));
    REQUIRE(VALID_ECDBNODE(node));
    REQUIRE(targetp != NULL && *targetp == NULL);

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

    *targetp = node;
}

static void
destroynode(dns_ecdbnode_t *node) {
    isc_mem_t *mctx;
    dns_ecdb_t *ecdb = node->ecdb;
    isc_boolean_t need_destroydb = ISC_FALSE;
    rdatasetheader_t *header;

    mctx = ecdb->common.mctx;

    LOCK(&ecdb->lock);
    ISC_LIST_UNLINK(ecdb->nodes, node, link);
    if (ecdb->references == 0 && ISC_LIST_EMPTY(ecdb->nodes))
        need_destroydb = ISC_TRUE;
    UNLOCK(&ecdb->lock);

    dns_name_free(&node->name, mctx);

    while ((header = ISC_LIST_HEAD(node->rdatasets)) != NULL) {
        unsigned int headersize;

        ISC_LIST_UNLINK(node->rdatasets, header, link);
        headersize =
            dns_rdataslab_size((unsigned char *)header,
                       sizeof(*header));
        isc_mem_put(mctx, header, headersize);
    }

    DESTROYLOCK(&node->lock);

    node->magic = 0;
    isc_mem_put(mctx, node, sizeof(*node));

    if (need_destroydb)
        destroy_ecdb(&ecdb);
}

static void
detachnode(dns_db_t *db, dns_dbnode_t **nodep) {
    dns_ecdb_t *ecdb = (dns_ecdb_t *)db;
    dns_ecdbnode_t *node;
    isc_boolean_t need_destroy = ISC_FALSE;

    REQUIRE(VALID_ECDB(ecdb));
    REQUIRE(nodep != NULL);
    node = (dns_ecdbnode_t *)*nodep;
    REQUIRE(VALID_ECDBNODE(node));

    UNUSED(ecdb);       /* in case REQUIRE() is empty */

    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);

    *nodep = NULL;
}

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)
{
    dns_ecdb_t *ecdb = (dns_ecdb_t *)db;

    REQUIRE(VALID_ECDB(ecdb));

    UNUSED(name);
    UNUSED(version);
    UNUSED(type);
    UNUSED(options);
    UNUSED(now);
    UNUSED(nodep);
    UNUSED(foundname);
    UNUSED(rdataset);
    UNUSED(sigrdataset);

    return (ISC_R_NOTFOUND);
}

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)
{
    dns_ecdb_t *ecdb = (dns_ecdb_t *)db;

    REQUIRE(VALID_ECDB(ecdb));

    UNUSED(name);
    UNUSED(options);
    UNUSED(now);
    UNUSED(nodep);
    UNUSED(foundname);
    UNUSED(rdataset);
    UNUSED(sigrdataset);

    return (ISC_R_NOTFOUND);
}

static isc_result_t
findnode(dns_db_t *db, dns_name_t *name, isc_boolean_t create,
     dns_dbnode_t **nodep)
{
    dns_ecdb_t *ecdb = (dns_ecdb_t *)db;
    isc_mem_t *mctx;
    dns_ecdbnode_t *node;
    isc_result_t result;

    REQUIRE(VALID_ECDB(ecdb));
    REQUIRE(nodep != NULL && *nodep == NULL);

    UNUSED(name);

    if (create != ISC_TRUE) {
        /* an 'ephemeral' node is never reused. */
        return (ISC_R_NOTFOUND);
    }

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

    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(mctx, node, sizeof(*node));
        return (ISC_R_UNEXPECTED);
    }

    dns_name_init(&node->name, NULL);
    result = dns_name_dup(name, mctx, &node->name);
    if (result != ISC_R_SUCCESS) {
        DESTROYLOCK(&node->lock);
        isc_mem_put(mctx, node, sizeof(*node));
        return (result);
    }
    node->ecdb= ecdb;
    node->references = 1;
    ISC_LIST_INIT(node->rdatasets);

    ISC_LINK_INIT(node, link);

    LOCK(&ecdb->lock);
    ISC_LIST_APPEND(ecdb->nodes, node, link);
    UNLOCK(&ecdb->lock);

    node->magic = ECDBNODE_MAGIC;

    *nodep = node;

    return (ISC_R_SUCCESS);
}

static void
bind_rdataset(dns_ecdb_t *ecdb, dns_ecdbnode_t *node,
          rdatasetheader_t *header, dns_rdataset_t *rdataset)
{
    unsigned char *raw;

    /*
     * Caller must be holding the node lock.
     */

    REQUIRE(!dns_rdataset_isassociated(rdataset));

    rdataset->methods = &rdataset_methods;
    rdataset->rdclass = ecdb->common.rdclass;
    rdataset->type = header->type;
    rdataset->covers = header->covers;
    rdataset->ttl = header->ttl;
    rdataset->trust = header->trust;
    if (NXDOMAIN(header))
        rdataset->attributes |= DNS_RDATASETATTR_NXDOMAIN;
    if (NEGATIVE(header))
        rdataset->attributes |= DNS_RDATASETATTR_NEGATIVE;

    rdataset->private1 = ecdb;
    rdataset->private2 = node;
    raw = (unsigned char *)header + sizeof(*header);
    rdataset->private3 = raw;
    rdataset->count = 0;

    /*
     * Reset iterator state.
     */
    rdataset->privateuint4 = 0;
    rdataset->private5 = NULL;

    INSIST(node->references > 0);
    node->references++;
}

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_ecdb_t *ecdb = (dns_ecdb_t *)db;
    isc_region_t r;
    isc_result_t result = ISC_R_SUCCESS;
    isc_mem_t *mctx;
    dns_ecdbnode_t *ecdbnode = (dns_ecdbnode_t *)node;
    rdatasetheader_t *header;

    REQUIRE(VALID_ECDB(ecdb));
    REQUIRE(VALID_ECDBNODE(ecdbnode));

    UNUSED(version);
    UNUSED(now);
    UNUSED(options);

    mctx = ecdb->common.mctx;

    LOCK(&ecdbnode->lock);

    /*
     * Sanity check: this implementation does not allow overriding an
     * existing rdataset of the same type.
     */
    for (header = ISC_LIST_HEAD(ecdbnode->rdatasets); header != NULL;
         header = ISC_LIST_NEXT(header, link)) {
        INSIST(header->type != rdataset->type ||
               header->covers != rdataset->covers);
    }

    result = dns_rdataslab_fromrdataset(rdataset, mctx,
                        &r, sizeof(rdatasetheader_t));
    if (result != ISC_R_SUCCESS)
        goto unlock;

    header = (rdatasetheader_t *)r.base;
    header->type = rdataset->type;
    header->ttl = rdataset->ttl;
    header->trust = rdataset->trust;
    header->covers = rdataset->covers;
    header->attributes = 0;
    if ((rdataset->attributes & DNS_RDATASETATTR_NXDOMAIN) != 0)
        header->attributes |= RDATASET_ATTR_NXDOMAIN;
    if ((rdataset->attributes & DNS_RDATASETATTR_NEGATIVE) != 0)
        header->attributes |= RDATASET_ATTR_NEGATIVE;
    ISC_LINK_INIT(header, link);
    ISC_LIST_APPEND(ecdbnode->rdatasets, header, link);

    if (addedrdataset == NULL)
        goto unlock;

    bind_rdataset(ecdb, ecdbnode, header, addedrdataset);

 unlock:
    UNLOCK(&ecdbnode->lock);

    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)
{
    UNUSED(db);
    UNUSED(node);
    UNUSED(version);
    UNUSED(type);
    UNUSED(covers);

    return (ISC_R_NOTIMPLEMENTED);
}

static isc_result_t
createiterator(dns_db_t *db, unsigned int options,
           dns_dbiterator_t **iteratorp)
{
    UNUSED(db);
    UNUSED(options);
    UNUSED(iteratorp);

    return (ISC_R_NOTIMPLEMENTED);
}

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_ecdb_t *ecdb = (dns_ecdb_t *)db;
    dns_ecdbnode_t *ecdbnode = (dns_ecdbnode_t *)node;
    isc_mem_t *mctx;
    ecdb_rdatasetiter_t *iterator;

    REQUIRE(VALID_ECDB(ecdb));
    REQUIRE(VALID_ECDBNODE(ecdbnode));

    mctx = ecdb->common.mctx;

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

static isc_result_t
dns_ecdb_create(isc_mem_t *mctx, dns_name_t *origin, dns_dbtype_t type,
        dns_rdataclass_t rdclass, unsigned int argc, char *argv[],
        void *driverarg, dns_db_t **dbp)
{
    dns_ecdb_t *ecdb;
    isc_result_t result;

    REQUIRE(mctx != NULL);
    REQUIRE(origin == dns_rootname);
    REQUIRE(type == dns_dbtype_cache);
    REQUIRE(dbp != NULL && *dbp == NULL);

    UNUSED(argc);
    UNUSED(argv);
    UNUSED(driverarg);

    ecdb = isc_mem_get(mctx, sizeof(*ecdb));
    if (ecdb == NULL)
        return (ISC_R_NOMEMORY);

    ecdb->common.attributes = DNS_DBATTR_CACHE;
    ecdb->common.rdclass = rdclass;
    ecdb->common.methods = &ecdb_methods;
    dns_name_init(&ecdb->common.origin, NULL);
    result = dns_name_dupwithoffsets(origin, mctx, &ecdb->common.origin);
    if (result != ISC_R_SUCCESS) {
        isc_mem_put(mctx, ecdb, sizeof(*ecdb));
        return (result);
    }

    result = isc_mutex_init(&ecdb->lock);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_mutex_init() failed: %s",
                 isc_result_totext(result));
        if (dns_name_dynamic(&ecdb->common.origin))
            dns_name_free(&ecdb->common.origin, mctx);
        isc_mem_put(mctx, ecdb, sizeof(*ecdb));
        return (ISC_R_UNEXPECTED);
    }

    ecdb->references = 1;
    ISC_LIST_INIT(ecdb->nodes);

    ecdb->common.mctx = NULL;
    isc_mem_attach(mctx, &ecdb->common.mctx);
    ecdb->common.impmagic = ECDB_MAGIC;
    ecdb->common.magic = DNS_DB_MAGIC;

    *dbp = (dns_db_t *)ecdb;

    return (ISC_R_SUCCESS);
}

/*%
 * Rdataset Methods
 */

static void
rdataset_disassociate(dns_rdataset_t *rdataset) {
    dns_db_t *db = rdataset->private1;
    dns_dbnode_t *node = rdataset->private2;

    dns_db_detachnode(db, &node);
}

static isc_result_t
rdataset_first(dns_rdataset_t *rdataset) {
    unsigned char *raw = rdataset->private3;
    unsigned int count;

    count = raw[0] * 256 + raw[1];
    if (count == 0) {
        rdataset->private5 = NULL;
        return (ISC_R_NOMORE);
    }
#if DNS_RDATASET_FIXED
    raw += 2 + (4 * count);
#else
    raw += 2;
#endif
    /*
     * The privateuint4 field is the number of rdata beyond the cursor
     * position, so we decrement the total count by one before storing
     * it.
     */
    count--;
    rdataset->privateuint4 = count;
    rdataset->private5 = raw;

    return (ISC_R_SUCCESS);
}

static isc_result_t
rdataset_next(dns_rdataset_t *rdataset) {
    unsigned int count;
    unsigned int length;
    unsigned char *raw;

    count = rdataset->privateuint4;
    if (count == 0)
        return (ISC_R_NOMORE);
    count--;
    rdataset->privateuint4 = count;
    raw = rdataset->private5;
    length = raw[0] * 256 + raw[1];
#if DNS_RDATASET_FIXED
    raw += length + 4;
#else
    raw += length + 2;
#endif
    rdataset->private5 = raw;

    return (ISC_R_SUCCESS);
}

static void
rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
    unsigned char *raw = rdataset->private5;
    isc_region_t r;
    unsigned int length;
    unsigned int flags = 0;

    REQUIRE(raw != NULL);

    length = raw[0] * 256 + raw[1];
#if DNS_RDATASET_FIXED
    raw += 4;
#else
    raw += 2;
#endif
    if (rdataset->type == dns_rdatatype_rrsig) {
        if (*raw & DNS_RDATASLAB_OFFLINE)
            flags |= DNS_RDATA_OFFLINE;
        length--;
        raw++;
    }
    r.length = length;
    r.base = raw;
    dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
    rdata->flags |= flags;
}

static void
rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
    dns_db_t *db = source->private1;
    dns_dbnode_t *node = source->private2;
    dns_dbnode_t *cloned_node = NULL;

    attachnode(db, node, &cloned_node);
    *target = *source;

    /*
     * Reset iterator state.
     */
    target->privateuint4 = 0;
    target->private5 = NULL;
}

static unsigned int
rdataset_count(dns_rdataset_t *rdataset) {
    unsigned char *raw = rdataset->private3;
    unsigned int count;

    count = raw[0] * 256 + raw[1];

    return (count);
}

static void
rdataset_settrust(dns_rdataset_t *rdataset, dns_trust_t trust) {
    rdatasetheader_t *header = rdataset->private3;

    header--;
    header->trust = rdataset->trust = trust;
}

/*
 * Rdataset Iterator Methods
 */

static void
rdatasetiter_destroy(dns_rdatasetiter_t **iteratorp) {
    isc_mem_t *mctx;
    union {
        dns_rdatasetiter_t *rdatasetiterator;
        ecdb_rdatasetiter_t *ecdbiterator;
    } u;

    REQUIRE(iteratorp != NULL);
    REQUIRE(DNS_RDATASETITER_VALID(*iteratorp));

    u.rdatasetiterator = *iteratorp;

    mctx = u.ecdbiterator->common.db->mctx;
    u.ecdbiterator->common.magic = 0;

    dns_db_detachnode(u.ecdbiterator->common.db,
              &u.ecdbiterator->common.node);
    isc_mem_put(mctx, u.ecdbiterator,
            sizeof(ecdb_rdatasetiter_t));

    *iteratorp = NULL;
}

static isc_result_t
rdatasetiter_first(dns_rdatasetiter_t *iterator) {
    ecdb_rdatasetiter_t *ecdbiterator = (ecdb_rdatasetiter_t *)iterator;
    dns_ecdbnode_t *ecdbnode = (dns_ecdbnode_t *)iterator->node;

    REQUIRE(DNS_RDATASETITER_VALID(iterator));

    if (ISC_LIST_EMPTY(ecdbnode->rdatasets))
        return (ISC_R_NOMORE);
    ecdbiterator->current = ISC_LIST_HEAD(ecdbnode->rdatasets);
    return (ISC_R_SUCCESS);
}

static isc_result_t
rdatasetiter_next(dns_rdatasetiter_t *iterator) {
    ecdb_rdatasetiter_t *ecdbiterator = (ecdb_rdatasetiter_t *)iterator;

    REQUIRE(DNS_RDATASETITER_VALID(iterator));

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

static void
rdatasetiter_current(dns_rdatasetiter_t *iterator, dns_rdataset_t *rdataset) {
    ecdb_rdatasetiter_t *ecdbiterator = (ecdb_rdatasetiter_t *)iterator;
    dns_ecdb_t *ecdb;

    ecdb = (dns_ecdb_t *)iterator->db;
    REQUIRE(VALID_ECDB(ecdb));

    bind_rdataset(ecdb, iterator->node, ecdbiterator->current, rdataset);
}