/*  Copyright (C) 2011 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <assert.h>

#include "updates/ddns.h"
#include "updates/changesets.h"
#include "util/debug.h"
#include "packet/packet.h"
#include "consts.h"

/*----------------------------------------------------------------------------*/
// Copied from XFR - maybe extract somewhere else
static int knot_ddns_prereq_check_rrsets(knot_rrset_t ***rrsets,
                                         size_t *count, size_t *allocated)
{
	int new_count = 0;
	if (*count == *allocated) {
		new_count = *allocated * 2;
	}

	knot_rrset_t **rrsets_new =
		(knot_rrset_t **)calloc(new_count, sizeof(knot_rrset_t *));
	if (rrsets_new == NULL) {
		return KNOT_ENOMEM;
	}

	memcpy(rrsets_new, *rrsets, (*count) * sizeof(knot_rrset_t *));
	*rrsets = rrsets_new;
	*allocated = new_count;

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_prereq_check_dnames(knot_dname_t ***dnames,
                                         size_t *count, size_t *allocated)
{
	int new_count = 0;
	if (*count == *allocated) {
		new_count = *allocated * 2;
	}

	knot_dname_t **dnames_new =
		(knot_dname_t **)calloc(new_count, sizeof(knot_dname_t *));
	if (dnames_new == NULL) {
		return KNOT_ENOMEM;
	}

	memcpy(dnames_new, *dnames, (*count) * sizeof(knot_dname_t *));
	*dnames = dnames_new;
	*allocated = new_count;

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_add_prereq_rrset(const knot_rrset_t *rrset,
                                      knot_rrset_t ***rrsets,
                                      size_t *count, size_t *allocd)
{
	// check if such RRSet is not already there and merge if needed
	int ret;
	for (int i = 0; i < *count; ++i) {
		if (knot_rrset_compare(rrset, (*rrsets)[i],
		                       KNOT_RRSET_COMPARE_HEADER) == 0) {
			ret = knot_rrset_merge((void **)&((*rrsets)[i]),
			                       (void **)&rrset);
			if (ret != KNOT_EOK) {
				return ret;
			} else {
				return KNOT_EOK;
			}
		}
	}

	// if we are here, the RRSet was not found
	ret = knot_ddns_prereq_check_rrsets(rrsets, count, allocd);
	if (ret != KNOT_EOK) {
		return ret;
	}

	knot_rrset_t *new_rrset = NULL;
	ret = knot_rrset_deep_copy(rrset, &new_rrset, 0);
	if (ret != KNOT_EOK) {
		return ret;
	}

	(*rrsets)[(*count)++] = new_rrset;

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_add_prereq_dname(const knot_dname_t *dname,
                                      knot_dname_t ***dnames,
                                      size_t *count, size_t *allocd)
{
	// we do not have to check if the name is not already there
	// if it is, we will just check it twice in the zone

	int ret = knot_ddns_prereq_check_dnames(dnames, count, allocd);
	if (ret != KNOT_EOK) {
		return ret;
	}

	knot_dname_t *dname_new = knot_dname_deep_copy(dname);
	if (dname_new == NULL) {
		return KNOT_ENOMEM;
	}

	(*dnames)[(*count)++] = dname_new;

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_add_prereq(knot_ddns_prereq_t *prereqs,
                                const knot_rrset_t *rrset, uint16_t qclass)
{
	assert(prereqs != NULL);
	assert(rrset != NULL);

	if (knot_rrset_ttl(rrset) != 0) {
		return KNOT_EMALF;
	}

	int ret;

	if (knot_rrset_class(rrset) == KNOT_CLASS_ANY) {
		if (knot_rrset_rdata(rrset) != NULL) {
			return KNOT_EMALF;
		}
		if (knot_rrset_type(rrset) == KNOT_RRTYPE_ANY) {
			ret = knot_ddns_add_prereq_dname(
				knot_rrset_owner(rrset), &prereqs->in_use,
				&prereqs->in_use_count,
				&prereqs->in_use_allocd);
		} else {
			ret = knot_ddns_add_prereq_rrset(rrset,
			                                &prereqs->exist,
			                                &prereqs->exist_count,
			                                &prereqs->exist_allocd);
		}
	} else if (knot_rrset_class(rrset) == KNOT_CLASS_NONE) {
		if (knot_rrset_rdata(rrset) != NULL) {
			return KNOT_EMALF;
		}
		if (knot_rrset_type(rrset) == KNOT_RRTYPE_ANY) {
			ret = knot_ddns_add_prereq_dname(
				knot_rrset_owner(rrset), &prereqs->not_in_use,
				&prereqs->not_in_use_count,
				&prereqs->not_in_use_allocd);
		} else {
			ret = knot_ddns_add_prereq_rrset(rrset,
			                            &prereqs->not_exist,
			                            &prereqs->not_exist_count,
			                            &prereqs->not_exist_allocd);
		}
	} else if (knot_rrset_class(rrset) == qclass) {
		ret = knot_ddns_add_prereq_rrset(rrset,
		                                 &prereqs->exist_full,
		                                 &prereqs->exist_full_count,
		                                 &prereqs->exist_full_allocd);
	} else {
		return KNOT_EMALF;
	}

	return ret;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_add_update(knot_changeset_t *changeset,
                         const knot_rrset_t *rrset, uint16_t qclass)
{
	assert(changeset != NULL);
	assert(rrset != NULL);

	int ret;

	// create a copy of the RRSet
	/*! \todo If the packet was not parsed all at once, we could save this
	 *        copy.
	 */
	knot_rrset_t *rrset_copy;
	ret = knot_rrset_deep_copy(rrset, &rrset_copy, 0);
	if (ret != KNOT_EOK) {
		return ret;
	}

	/*! \todo What about the SOAs? */

	if (knot_rrset_class(rrset) == qclass) {
		// this RRSet should be added to the zone
		ret = knot_changeset_add_rr(&changeset->add,
		                            &changeset->add_count,
		                            &changeset->add_allocated,
		                            rrset_copy);
	} else {
		// this RRSet marks removal of something from zone
		// what should be removed is distinguished when applying
		ret = knot_changeset_add_rr(&changeset->remove,
		                            &changeset->remove_count,
		                            &changeset->remove_allocated,
		                            rrset_copy);
	}

	return ret;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_check_exist(const knot_zone_contents_t *zone,
                                 const knot_rrset_t *rrset, uint8_t *rcode)
{
	assert(zone != NULL);
	assert(rrset != NULL);
	assert(rcode != NULL);
	assert(knot_rrset_rdata(rrset) == NULL);
	assert(knot_rrset_type(rrset) != KNOT_RRTYPE_ANY);
	assert(knot_rrset_ttl(rrset) == 0);
	assert(knot_rrset_class(rrset) == KNOT_CLASS_ANY);

	if (!knot_dname_is_subdomain(knot_rrset_owner(rrset),
	    knot_node_owner(knot_zone_contents_apex(zone)))) {
		*rcode = KNOT_RCODE_NOTZONE;
		return KNOT_EBADZONE;
	}

	const knot_node_t *node;
	node = knot_zone_contents_find_node(zone, knot_rrset_owner(rrset));
	if (node == NULL) {
		*rcode = KNOT_RCODE_NXRRSET;
		return KNOT_ENONODE;
	} else if (knot_node_rrset(node, knot_rrset_type(rrset)) == NULL) {
		*rcode = KNOT_RCODE_NXRRSET;
		return KNOT_ENORRSET;
	}

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_check_exist_full(const knot_zone_contents_t *zone,
                                      const knot_rrset_t *rrset, uint8_t *rcode)
{
	assert(zone != NULL);
	assert(rrset != NULL);
	assert(rcode != NULL);
	assert(knot_rrset_rdata(rrset) == NULL);
	assert(knot_rrset_type(rrset) != KNOT_RRTYPE_ANY);
	assert(knot_rrset_ttl(rrset) == 0);
	assert(knot_rrset_class(rrset) == KNOT_CLASS_ANY);

	if (!knot_dname_is_subdomain(knot_rrset_owner(rrset),
	    knot_node_owner(knot_zone_contents_apex(zone)))) {
		*rcode = KNOT_RCODE_NOTZONE;
		return KNOT_EBADZONE;
	}

	const knot_node_t *node;
	const knot_rrset_t *found;

	node = knot_zone_contents_find_node(zone, knot_rrset_owner(rrset));
	if (node == NULL) {
		*rcode = KNOT_RCODE_NXRRSET;
		return KNOT_EPREREQ;
	} else if ((found = knot_node_rrset(node, knot_rrset_type(rrset)))
	            == NULL) {
		*rcode = KNOT_RCODE_NXRRSET;
		return KNOT_EPREREQ;
	} else {
		// do not have to compare the header, it is already done
		assert(knot_rrset_type(found) == knot_rrset_type(rrset));
		assert(knot_dname_compare(knot_rrset_owner(found),
		                          knot_rrset_owner(rrset)) == 0);
		if (knot_rrset_compare_rdata(found, rrset) <= 0) {
			*rcode = KNOT_RCODE_NXRRSET;
			return KNOT_EPREREQ;
		}
	}

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_check_not_exist(const knot_zone_contents_t *zone,
                                     const knot_rrset_t *rrset, uint8_t *rcode)
{
	assert(zone != NULL);
	assert(rrset != NULL);
	assert(rcode != NULL);
	assert(knot_rrset_rdata(rrset) == NULL);
	assert(knot_rrset_type(rrset) != KNOT_RRTYPE_ANY);
	assert(knot_rrset_ttl(rrset) == 0);
	assert(knot_rrset_class(rrset) == KNOT_CLASS_NONE);

	if (!knot_dname_is_subdomain(knot_rrset_owner(rrset),
	    knot_node_owner(knot_zone_contents_apex(zone)))) {
		*rcode = KNOT_RCODE_NOTZONE;
		return KNOT_EBADZONE;
	}

	const knot_node_t *node;
	const knot_rrset_t *found;

	node = knot_zone_contents_find_node(zone, knot_rrset_owner(rrset));
	if (node == NULL) {
		return KNOT_EOK;
	} else if ((found = knot_node_rrset(node, knot_rrset_type(rrset)))
	            == NULL) {
		return KNOT_EOK;
	} else {
		// do not have to compare the header, it is already done
		assert(knot_rrset_type(found) == knot_rrset_type(rrset));
		assert(knot_dname_compare(knot_rrset_owner(found),
		                          knot_rrset_owner(rrset)) == 0);
		if (knot_rrset_compare_rdata(found, rrset) <= 0) {
			return KNOT_EOK;
		}
	}

	*rcode = KNOT_RCODE_YXRRSET;
	return KNOT_EPREREQ;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_check_in_use(const knot_zone_contents_t *zone,
                                  const knot_dname_t *dname, uint8_t *rcode)
{
	assert(zone != NULL);
	assert(dname != NULL);
	assert(rcode != NULL);

	if (!knot_dname_is_subdomain(dname,
	    knot_node_owner(knot_zone_contents_apex(zone)))) {
		*rcode = KNOT_RCODE_NOTZONE;
		return KNOT_EBADZONE;
	}

	const knot_node_t *node;

	node = knot_zone_contents_find_node(zone, dname);
	if (node == NULL) {
		*rcode = KNOT_RCODE_NXDOMAIN;
		return KNOT_EPREREQ;
	} else if (knot_node_rrset_count(node) == 0) {
		*rcode = KNOT_RCODE_NXDOMAIN;
		return KNOT_EPREREQ;
	}

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_check_not_in_use(const knot_zone_contents_t *zone,
                                      const knot_dname_t *dname, uint8_t *rcode)
{
	assert(zone != NULL);
	assert(dname != NULL);
	assert(rcode != NULL);

	if (!knot_dname_is_subdomain(dname,
	    knot_node_owner(knot_zone_contents_apex(zone)))) {
		*rcode = KNOT_RCODE_NOTZONE;
		return KNOT_EBADZONE;
	}

	const knot_node_t *node;

	node = knot_zone_contents_find_node(zone, dname);
	if (node == NULL) {
		return KNOT_EOK;
	} else if (knot_node_rrset_count(node) == 0) {
		return KNOT_EOK;
	}

	*rcode = KNOT_RCODE_YXDOMAIN;
	return KNOT_EPREREQ;
}

/*----------------------------------------------------------------------------*/
/* API functions                                                              */
/*----------------------------------------------------------------------------*/

int knot_ddns_check_zone(const knot_zone_t *zone, knot_packet_t *query,
                         uint8_t *rcode)
{
	if (zone == NULL || query == NULL || rcode == NULL) {
		return KNOT_EINVAL;
	}

	if (knot_packet_qtype(query) != KNOT_RRTYPE_SOA) {
		*rcode = KNOT_RCODE_FORMERR;
		return KNOT_EMALF;
	}

	if(!knot_zone_contents(zone)) {
		*rcode = KNOT_RCODE_REFUSED;
		return KNOT_ENOZONE;
	}

	// 1) check if the zone is master or slave
	if (!knot_zone_is_master(zone)) {
		return KNOT_EBADZONE;
	}

	// 2) check zone CLASS
	if (knot_zone_contents_class(knot_zone_contents(zone)) !=
	    knot_packet_qclass(query)) {
		*rcode = KNOT_RCODE_NOTAUTH;
		return KNOT_ENOZONE;
	}

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

int knot_ddns_process_prereqs(knot_packet_t *query,
                              knot_ddns_prereq_t **prereqs, uint8_t *rcode)
{
	/*! \todo Consider not parsing the whole packet at once, but
	 *        parsing one RR at a time - could save some memory and time.
	 */

	if (query == NULL || prereqs == NULL || rcode == NULL) {
		return KNOT_EINVAL;
	}

	// allocate space for the prerequisities
	*prereqs = (knot_ddns_prereq_t *)calloc(1, sizeof(knot_ddns_prereq_t));
	CHECK_ALLOC_LOG(*prereqs, KNOT_ENOMEM);

	int ret;

	for (int i = 0; i < knot_packet_answer_rrset_count(query); ++i) {
		// we must copy the RRSets, because all those stored in the
		// packet will be destroyed
		ret = knot_ddns_add_prereq(*prereqs,
		                           knot_packet_answer_rrset(query, i),
		                           knot_packet_qclass(query));
		if (ret != KNOT_EOK) {
			dbg_ddns("Failed to add prerequisity RRSet:%s\n",
			                knot_strerror(ret));
			*rcode = (ret == KNOT_EMALF) ? KNOT_RCODE_FORMERR
			                             : KNOT_RCODE_SERVFAIL;
			knot_ddns_prereqs_free(prereqs);
			return ret;
		}
	}

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

int knot_ddns_check_prereqs(const knot_zone_contents_t *zone,
                            knot_ddns_prereq_t **prereqs, uint8_t *rcode)
{
	int i, ret;

	for (i = 0; i < (*prereqs)->exist_count; ++i) {
		ret = knot_ddns_check_exist(zone, (*prereqs)->exist[i], rcode);
		if (ret != KNOT_EOK) {
			return ret;
		}
	}

	for (i = 0; i < (*prereqs)->exist_full_count; ++i) {
		ret = knot_ddns_check_exist_full(zone,
		                                (*prereqs)->exist_full[i],
		                                 rcode);
		if (ret != KNOT_EOK) {
			return ret;
		}
	}

	for (i = 0; i < (*prereqs)->not_exist_count; ++i) {
		ret = knot_ddns_check_not_exist(zone, (*prereqs)->not_exist[i],
		                                rcode);
		if (ret != KNOT_EOK) {
			return ret;
		}
	}

	for (i = 0; i < (*prereqs)->in_use_count; ++i) {
		ret = knot_ddns_check_in_use(zone, (*prereqs)->in_use[i],
		                             rcode);
		if (ret != KNOT_EOK) {
			return ret;
		}
	}

	for (i = 0; i < (*prereqs)->not_in_use_count; ++i) {
		ret = knot_ddns_check_not_in_use(zone,
		                                 (*prereqs)->not_in_use[i],
		                                 rcode);
		if (ret != KNOT_EOK) {
			return ret;
		}
	}

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

static int knot_ddns_check_update(const knot_rrset_t *rrset,
                                  const knot_packet_t *query, uint8_t *rcode)
{
	if (!knot_dname_is_subdomain(knot_rrset_owner(rrset),
	                             knot_packet_qname(query))) {
		*rcode = KNOT_RCODE_NOTZONE;
		return KNOT_EBADZONE;
	}

	if (knot_rrset_class(rrset) == knot_packet_qclass(query)) {
		if (knot_rrtype_is_metatype(knot_rrset_type(rrset))) {
			*rcode = KNOT_RCODE_FORMERR;
			return KNOT_EMALF;
		}
	} else if (knot_rrset_class(rrset) == KNOT_CLASS_ANY) {
		if (knot_rrset_rdata(rrset) != NULL
		    || (knot_rrtype_is_metatype(knot_rrset_type(rrset))
		        && knot_rrset_type(rrset) != KNOT_RRTYPE_ANY)) {
			*rcode = KNOT_RCODE_FORMERR;
			return KNOT_EMALF;
		}
	} else if (knot_rrset_class(rrset) == KNOT_CLASS_NONE) {
		if (knot_rrset_ttl(rrset) != 0
		    || knot_rrtype_is_metatype(knot_rrset_type(rrset))) {
			*rcode = KNOT_RCODE_FORMERR;
			return KNOT_EMALF;
		}
	} else {
		*rcode = KNOT_RCODE_FORMERR;
		return KNOT_EMALF;
	}

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

int knot_ddns_process_update(knot_packet_t *query,
                             knot_changeset_t **changeset, uint8_t *rcode)
{
	// just put all RRSets from query's Authority section
	// it will be distinguished when applying to the zone

	if (query == NULL || changeset == NULL || rcode == NULL) {
		return KNOT_EINVAL;
	}

	*changeset = (knot_changeset_t *)calloc(1, sizeof(knot_changeset_t));
	CHECK_ALLOC_LOG(*changeset, KNOT_ENOMEM);

	int ret;

	for (int i = 0; i < knot_packet_authority_rrset_count(query); ++i) {

		const knot_rrset_t *rrset =
				knot_packet_authority_rrset(query, i);

		ret = knot_ddns_check_update(rrset, query, rcode);
		if (ret != KNOT_EOK) {
			return ret;
		}

		ret = knot_ddns_add_update(*changeset, rrset,
		                          knot_packet_qclass(query));

		if (ret != KNOT_EOK) {
			dbg_ddns("Failed to add update RRSet:%s\n",
			                knot_strerror(ret));
			*rcode = (ret == KNOT_EMALF) ? KNOT_RCODE_FORMERR
			                             : KNOT_RCODE_SERVFAIL;
			knot_free_changeset(changeset);
			return ret;
		}
	}

	return KNOT_EOK;
}

/*----------------------------------------------------------------------------*/

void knot_ddns_prereqs_free(knot_ddns_prereq_t **prereq)
{
	int i;

	for (i = 0; i < (*prereq)->exist_count; ++i) {
		knot_rrset_deep_free(&(*prereq)->exist[i], 1, 1, 1);
	}

	for (i = 0; i < (*prereq)->exist_full_count; ++i) {
		knot_rrset_deep_free(&(*prereq)->exist_full[i], 1, 1, 1);
	}

	for (i = 0; i < (*prereq)->not_exist_count; ++i) {
		knot_rrset_deep_free(&(*prereq)->not_exist[i], 1, 1, 1);
	}

	for (i = 0; i < (*prereq)->in_use_count; ++i) {
		knot_dname_free(&(*prereq)->in_use[i]);
	}

	for (i = 0; i < (*prereq)->not_in_use_count; ++i) {
		knot_dname_free(&(*prereq)->not_in_use[i]);
	}

	free(*prereq);
	*prereq = NULL;
}