/*
 * 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.
 */

/* $Id: rdataset.c,v 1.47 2000/07/27 09:46:29 tale Exp $ */

#include <config.h>

#include <stdlib.h>

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

#include <dns/name.h>
#include <dns/ncache.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->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.
		 */
		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);
}