/*
 * Copyright (C) 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.
 */

/*! \file */

#include <stdint.h>
#include <stdlib.h>

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

#include <dns/name.h>
#include <dns/rdata.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->methods = NULL;
        ISC_LINK_INIT(rdataset, link);
        rdataset->rdclass = 0;
        rdataset->type = 0;
        rdataset->ttl = 0;
        rdataset->covers = 0;
        rdataset->attributes = 0;
        rdataset->count = UINT32_MAX;
        rdataset->private1 = NULL;
        rdataset->private2 = NULL;
}

void
dns_rdataset_disassociate(dns_rdataset_t *rdataset) {

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

        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->covers = 0;
        rdataset->attributes = 0;
        rdataset->count = UINT32_MAX;
        rdataset->private1 = NULL;
        rdataset->private2 = NULL;
}

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

        if (rdataset->methods != NULL)
                return (1);

        return (0);
}

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

static isc_result_t
question_cursor(dns_rdataset_t *rdataset) {
        UNUSED(rdataset);

        return (ISC_R_NOMORE);
}

static void
question_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
        /*
         * This routine should never be called.
         */
        UNUSED(rdataset);
        UNUSED(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.
         */
        UNUSED(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(rdataset->methods == NULL);

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

isc_result_t
dns_rdataset_first(dns_rdataset_t *rdataset) {

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

        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(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(rdataset->methods != NULL);

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

#define MAX_SHUFFLE     32

struct towire_sort {
        int key;
        dns_rdata_t *rdata;
};

static isc_result_t
towiresorted(dns_rdataset_t *rdataset, const dns_name_t *owner_name,
             dns_compress_t *cctx, isc_buffer_t *target, unsigned int *countp)
{
        dns_rdata_t rdata = DNS_RDATA_INIT;
        isc_region_t r;
        isc_result_t result;
        unsigned int i, count = 0;
        isc_buffer_t savedbuffer, rdlen;
        unsigned int headlen;
        int question = 0;
        int shuffle = 0;
        dns_rdata_t *in = NULL, in_fixed[MAX_SHUFFLE];
        struct towire_sort *out = NULL, out_fixed[MAX_SHUFFLE];

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

        REQUIRE(rdataset->methods != NULL);
        REQUIRE(countp != NULL);
        REQUIRE(cctx != NULL);

        if ((rdataset->attributes & DNS_RDATASETATTR_QUESTION) != 0) {
                question = 1;
                count = 1;
                result = dns_rdataset_first(rdataset);
                INSIST(result == ISC_R_NOMORE);
        } 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);
        }

        /*
         * Do we want to shuffle this answer?
         */
        if (!question && count > 1 && rdataset->type != dns_rdatatype_rrsig)
                shuffle = 1;

        if (shuffle && count > MAX_SHUFFLE) {
                in = reallocarray(NULL, count, sizeof(*in));
                out = reallocarray(NULL, count, sizeof(*out));
                if (in == NULL || out == NULL)
                        shuffle = 0;
        } else {
                in = in_fixed;
                out = out_fixed;
        }

        if (shuffle) {
                uint32_t val;
                unsigned int j;

                /*
                 * First we get handles to all of the rdata.
                 */
                i = 0;
                do {
                        INSIST(i < count);
                        dns_rdata_init(&in[i]);
                        dns_rdataset_current(rdataset, &in[i]);
                        i++;
                        result = dns_rdataset_next(rdataset);
                } while (result == ISC_R_SUCCESS);
                if (result != ISC_R_NOMORE)
                        goto cleanup;
                INSIST(i == count);

                /*
                 * Now we shuffle.
                 */

                /*
                 * "Cyclic" order.
                 */

                val = rdataset->count;
                if (val == UINT32_MAX)
                        val = arc4random();
                j = val % count;
                for (i = 0; i < count; i++) {
                        out[i].key = 0; /* Unused */
                        out[i].rdata = &in[j];
                        j++;
                        if (j == count)
                                j = 0; /* Wrap around. */
                }
        }

        savedbuffer = *target;
        i = 0;

        do {
                /*
                 * Copy out the name, type, class, ttl.
                 */

                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 = *(out[i].rdata);
                        else {
                                dns_rdata_reset(&rdata);
                                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,
                                             (uint16_t)(target->used -
                                                            rdlen.used - 2));
                }

                if (shuffle) {
                        i++;
                        if (i == 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;

        result = ISC_R_SUCCESS;
        goto cleanup;

 rollback:
        INSIST(savedbuffer.used < 65536);
        dns_compress_rollback(cctx, (uint16_t)savedbuffer.used);
        *countp = 0;
        *target = savedbuffer;

 cleanup:
        if (out != NULL && out != out_fixed)
                free(out);
        if (in != NULL && in != in_fixed)
                free(in);
        return (result);
}

isc_result_t
dns_rdataset_towiresorted(dns_rdataset_t *rdataset,
                          const dns_name_t *owner_name,
                          dns_compress_t *cctx,
                          isc_buffer_t *target,
                          unsigned int *countp)
{
        return (towiresorted(rdataset, owner_name, cctx, target, countp));
}

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)
{
        return (towiresorted(rdataset, owner_name, cctx, target, countp));
}