lib/dns/rdataset.c

	rdataset.c revision 364a82f7c25b62967678027043425201a5e5171a
/*
 * Copyright (C) 1999, 2000  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

#include <config.h>

#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#include <isc/assertions.h>
#include <isc/util.h>

#include <dns/ncache.h>
#include <dns/rdata.h>
#include <dns/rdataclass.h>
#include <dns/rdatatype.h>
#include <dns/rdataset.h>
#include <dns/compress.h>

void
dns_rdataset_init(dns_rdataset_t *rdataset) {

    /*
     * Make 'rdataset' a valid, disassociated rdataset.
     */

    REQUIRE(rdataset != NULL);

    rdataset->magic = DNS_RDATASET_MAGIC;
    rdataset->methods = NULL;
    ISC_LINK_INIT(rdataset, link);
    rdataset->rdclass = 0;
    rdataset->type = 0;
    rdataset->ttl = 0;
    rdataset->trust = 0;
    rdataset->covers = 0;
    rdataset->attributes = 0;
    rdataset->private1 = NULL;
    rdataset->private2 = NULL;
    rdataset->private3 = NULL;
    rdataset->private4 = NULL;
    rdataset->private5 = NULL;
}

void
dns_rdataset_invalidate(dns_rdataset_t *rdataset) {

    /*
     * Invalidate 'rdataset'.
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    REQUIRE(rdataset->methods == NULL);

    rdataset->magic = 0;
    ISC_LINK_INIT(rdataset, link);
    rdataset->rdclass = 0;
    rdataset->type = 0;
    rdataset->ttl = 0;
    rdataset->trust = 0;
    rdataset->covers = 0;
    rdataset->attributes = 0;
    rdataset->private1 = NULL;
    rdataset->private2 = NULL;
    rdataset->private3 = NULL;
    rdataset->private4 = NULL;
    rdataset->private5 = NULL;
}

void
dns_rdataset_disassociate(dns_rdataset_t *rdataset) {

    /*
     * Disassociate 'rdataset' from its rdata, allowing it to be reused.
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    REQUIRE(rdataset->methods != NULL);

    (rdataset->methods->disassociate)(rdataset);
    rdataset->methods = NULL;
    ISC_LINK_INIT(rdataset, link);
    rdataset->rdclass = 0;
    rdataset->type = 0;
    rdataset->ttl = 0;
    rdataset->trust = 0;
    rdataset->covers = 0;
    rdataset->attributes = 0;
    rdataset->private1 = NULL;
    rdataset->private2 = NULL;
    rdataset->private3 = NULL;
    rdataset->private4 = NULL;
    rdataset->private5 = NULL;
}

isc_boolean_t
dns_rdataset_isassociated(dns_rdataset_t *rdataset) {
    /*
     * Is 'rdataset' associated?
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));

    if (rdataset->methods != NULL)
        return (ISC_TRUE);

    return (ISC_FALSE);
}

static void
question_disassociate(dns_rdataset_t *rdataset) {
    (void)rdataset;
}

static isc_result_t
question_cursor(dns_rdataset_t *rdataset) {
    (void)rdataset;
    return (ISC_R_NOMORE);
}

static void
question_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
    /*
     * This routine should never be called.
     */
    (void)rdataset;
    (void)rdata;
    REQUIRE(0);
}

static void
question_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
    *target = *source;
}

static unsigned int
question_count(dns_rdataset_t *rdataset) {
    /*
     * This routine should never be called.
     */
    (void)rdataset;
    REQUIRE(0);

    return (0);
}

static dns_rdatasetmethods_t question_methods = {
    question_disassociate,
    question_cursor,
    question_cursor,
    question_current,
    question_clone,
    question_count
};

void
dns_rdataset_makequestion(dns_rdataset_t *rdataset, dns_rdataclass_t rdclass,
              dns_rdatatype_t type)
{

    /*
     * Make 'rdataset' a valid, associated, question rdataset, with a
     * question class of 'rdclass' and type 'type'.
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    REQUIRE(rdataset->methods == NULL);

    rdataset->methods = &question_methods;
    rdataset->rdclass = rdclass;
    rdataset->type = type;
    rdataset->attributes |= DNS_RDATASETATTR_QUESTION;
}

unsigned int
dns_rdataset_count(dns_rdataset_t *rdataset) {

    /*
     * Return the number of records in 'rdataset'.
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    REQUIRE(rdataset->methods != NULL);

    return ((rdataset->methods->count)(rdataset));
}

void
dns_rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {

    /*
     * Make 'target' refer to the same rdataset as 'source'.
     */

    REQUIRE(DNS_RDATASET_VALID(source));
    REQUIRE(source->methods != NULL);
    REQUIRE(DNS_RDATASET_VALID(target));
    REQUIRE(target->methods == NULL);

    (source->methods->clone)(source, target);
}

isc_result_t
dns_rdataset_first(dns_rdataset_t *rdataset) {

    /*
     * Move the rdata cursor to the first rdata in the rdataset (if any).
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    REQUIRE(rdataset->methods != NULL);

    return ((rdataset->methods->first)(rdataset));
}

isc_result_t
dns_rdataset_next(dns_rdataset_t *rdataset) {

    /*
     * Move the rdata cursor to the next rdata in the rdataset (if any).
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    REQUIRE(rdataset->methods != NULL);

    return ((rdataset->methods->next)(rdataset));
}

void
dns_rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {

    /*
     * Make 'rdata' refer to the current rdata.
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    REQUIRE(rdataset->methods != NULL);

    (rdataset->methods->current)(rdataset, rdata);
}

#define MAX_SHUFFLE 32
#define WANT_FIXED(r)   (((r)->attributes & DNS_RDATASETATTR_FIXEDORDER) != 0)
#define WANT_RANDOM(r)  (((r)->attributes & DNS_RDATASETATTR_RANDOMIZE) != 0)


isc_result_t
dns_rdataset_towire(dns_rdataset_t *rdataset,
            dns_name_t *owner_name,
            dns_compress_t *cctx,
            isc_buffer_t *target,
            unsigned int *countp)
{
    dns_rdata_t rdata;
    isc_region_t r;
    isc_result_t result;
    unsigned int i, count, tcount, choice;
    isc_buffer_t savedbuffer, rdlen;
    unsigned int headlen;
    isc_boolean_t question = ISC_FALSE;
    isc_boolean_t shuffle = ISC_FALSE;
    dns_rdata_t shuffled[MAX_SHUFFLE];

    /*
     * Convert 'rdataset' to wire format, compressing names as specified
     * in cctx, and storing the result in 'target'.
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    REQUIRE(countp != NULL);

    count = 0;
    if ((rdataset->attributes & DNS_RDATASETATTR_QUESTION) != 0) {
        question = ISC_TRUE;
        count = 1;
        result = dns_rdataset_first(rdataset);
        INSIST(result == ISC_R_NOMORE);
    } else if (rdataset->type == 0) {
        /*
         * This is a negative caching rdataset.
         */
        return (dns_ncache_towire(rdataset, cctx, target, countp));
    } else {
        count = (rdataset->methods->count)(rdataset);
        result = dns_rdataset_first(rdataset);
        if (result == ISC_R_NOMORE)
            return (ISC_R_SUCCESS);
        if (result != ISC_R_SUCCESS)
            return (result);
    }

    choice = 0;
    if (!question && count > 1 && !WANT_FIXED(rdataset)) {
        /*
         * We'll only shuffle if we've got enough slots in our
         * deck.
         *
         * There's no point to shuffling SIGs.
         */
        if (count <= MAX_SHUFFLE &&
            rdataset->type != dns_rdatatype_sig) {
            shuffle = ISC_TRUE;
            /*
             * First we get handles to all of the rdata.
             */
            i = 0;
            do {
                INSIST(i < count);
                dns_rdataset_current(rdataset, &shuffled[i]);
                i++;
                result = dns_rdataset_next(rdataset);
            } while (result == ISC_R_SUCCESS);
            if (result != ISC_R_NOMORE)
                return (result);
            INSIST(i == count);
            /*
             * Now we shuffle.
             */
            if (WANT_RANDOM(rdataset)) {
                /*
                 * "Random" order.
                 */
                tcount = count;
                for (i = 0; i < count; i++) {
                    choice = (((unsigned int)rand()) >> 3)
                        % tcount;
                    rdata = shuffled[i];
                    shuffled[i] = shuffled[i + choice];
                    shuffled[i + choice] = rdata;
                    tcount--;
                }
                choice = 0;
            } else {
                /*
                 * "Cyclic" order.
                 */
                choice = (((unsigned int)rand()) >> 3) % count;
            }
        }
    }

    savedbuffer = *target;
    i = choice;
    tcount = 0;

    do {
        /*
         * copy out the name, type, class, ttl.
         */
        if (dns_compress_getedns(cctx) >= 1)
            dns_compress_setmethods(cctx, DNS_COMPRESS_GLOBAL);
        else
            dns_compress_setmethods(cctx, DNS_COMPRESS_GLOBAL14);
        result = dns_name_towire(owner_name, cctx, target);
        if (result != ISC_R_SUCCESS)
            goto rollback;
        headlen = sizeof(dns_rdataclass_t) + sizeof(dns_rdatatype_t);
        if (!question)
            headlen += sizeof(dns_ttl_t)
                + 2;  /* XXX 2 for rdata len */
        isc_buffer_availableregion(target, &r);
        if (r.length < headlen) {
            result = ISC_R_NOSPACE;
            goto rollback;
        }
        isc_buffer_putuint16(target, rdataset->type);
        isc_buffer_putuint16(target, rdataset->rdclass);
        if (!question) {
            isc_buffer_putuint32(target, rdataset->ttl);

            /*
             * Save space for rdlen.
             */
            rdlen = *target;
            isc_buffer_add(target, 2);

            /*
             * copy out the rdata
             */
            if (shuffle)
                rdata = shuffled[i];
            else
                dns_rdataset_current(rdataset, &rdata);
            result = dns_rdata_towire(&rdata, cctx, target);
            if (result != ISC_R_SUCCESS)
                goto rollback;
            INSIST((target->used >= rdlen.used + 2) &&
                   (target->used - rdlen.used - 2 < 65536));
            isc_buffer_putuint16(&rdlen,
                         (isc_uint16_t)(target->used -
                                rdlen.used - 2));
        }

        if (shuffle) {
            i++;
            /*
             * Wrap around in case we're doing cyclic ordering.
             */
            if (i == count)
                i = 0;
            tcount++;
            if (tcount == count)
                result = ISC_R_NOMORE;
            else
                result = ISC_R_SUCCESS;
        } else
            result = dns_rdataset_next(rdataset);
    } while (result == ISC_R_SUCCESS);

    if (result != ISC_R_NOMORE)
        goto rollback;

    *countp += count;

    return (ISC_R_SUCCESS);

 rollback:
    INSIST(savedbuffer.used < 65536);
    dns_compress_rollback(cctx, (isc_uint16_t)savedbuffer.used);
    *countp = 0;
    *target = savedbuffer;

    return (result);
}

isc_result_t
dns_rdataset_additionaldata(dns_rdataset_t *rdataset,
                dns_additionaldatafunc_t add, void *arg)
{
    dns_rdata_t rdata;
    isc_result_t result;

    /*
     * For each rdata in rdataset, call 'add' for each name and type in the
     * rdata which is subject to additional section processing.
     */

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    REQUIRE((rdataset->attributes & DNS_RDATASETATTR_QUESTION) == 0);

    result = dns_rdataset_first(rdataset);
    if (result != ISC_R_SUCCESS)
        return (result);

    do {
        dns_rdataset_current(rdataset, &rdata);
        result = dns_rdata_additionaldata(&rdata, add, arg);
        if (result == ISC_R_SUCCESS)
            result = dns_rdataset_next(rdataset);
    } while (result == ISC_R_SUCCESS);

    if (result != ISC_R_NOMORE)
        return (result);

    return (ISC_R_SUCCESS);
}