/*
 * nsec3.c -- nsec3 handling.
 *
 * Copyright (c) 2001-2011, NLnet Labs. All rights reserved.
 *
 * See LICENSE for the license.
 *
 */
#include <config.h>
#ifdef NSEC3
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

#include "nsec3.h"
#include "iterated_hash.h"
#include "namedb.h"
#include "nsd.h"
#include "answer.h"

#define NSEC3_SHA1_HASH 1 /* same type code as DS hash */


static void
detect_nsec3_params(rr_type* nsec3_apex,
	const unsigned char** salt, int* salt_len, int* iter)
{
	/* always uses first NSEC3 record with SOA bit set */
	assert(salt && salt_len && iter);
	assert(nsec3_apex);
	*salt_len = rdata_atom_data(nsec3_apex->rdatas[3])[0];
	*salt = (unsigned char*)(rdata_atom_data(nsec3_apex->rdatas[3])+1);
	*iter = read_uint16(rdata_atom_data(nsec3_apex->rdatas[2]));
}

static const dname_type *
nsec3_hash_dname_param(region_type *region, zone_type *zone,
	const dname_type *dname, rr_type* param_rr)
{
	unsigned char hash[SHA_DIGEST_LENGTH];
	char b32[SHA_DIGEST_LENGTH*2+1];
	const unsigned char* nsec3_salt = NULL;
	int nsec3_saltlength = 0;
	int nsec3_iterations = 0;

	detect_nsec3_params(param_rr, &nsec3_salt,
		&nsec3_saltlength, &nsec3_iterations);
	iterated_hash(hash, nsec3_salt, nsec3_saltlength, dname_name(dname),
		dname->name_size, nsec3_iterations);
	b32_ntop(hash, sizeof(hash), b32, sizeof(b32));
	dname=dname_parse(region, b32);
	dname=dname_concatenate(region, dname, domain_dname(zone->apex));
	return dname;
}

const dname_type *
nsec3_hash_dname(region_type *region, zone_type *zone,
	const dname_type *dname)
{
	return nsec3_hash_dname_param(region, zone,
		dname, zone->nsec3_soa_rr);
}

static int
nsec3_has_soa(rr_type* rr)
{
	if(rdata_atom_size(rr->rdatas[5]) >= 3 && /* has types in bitmap */
		rdata_atom_data(rr->rdatas[5])[0] == 0 && /* first window = 0, */
						/* [1]: windowlen must be >= 1 */
		rdata_atom_data(rr->rdatas[5])[2]&0x02)  /* SOA bit set */
		return 1;
	return 0;
}

static rr_type*
find_zone_nsec3(namedb_type* namedb, zone_type *zone)
{
	size_t i;
	domain_type* domain;
	region_type* tmpregion;
	/* Check settings in NSEC3PARAM.
	   Hash algorithm must be OK. And a NSEC3 with soa bit
	   must map to the zone apex.  */
	rrset_type* paramset = domain_find_rrset(zone->apex, zone, TYPE_NSEC3PARAM);
	if(!paramset || !paramset->rrs || !paramset->rr_count)
		return NULL;
	tmpregion = region_create(xalloc, free);
	for(i=0; i < paramset->rr_count; i++) {
		rr_type* rr = &paramset->rrs[i];
		const dname_type* hashed_apex;
		rrset_type* nsec3_rrset;
		size_t j;
		const unsigned char *salt1;
		int saltlen1, iter1;

		if(rdata_atom_data(rr->rdatas[0])[0] != NSEC3_SHA1_HASH) {
			log_msg(LOG_ERR, "%s NSEC3PARAM entry %d has unknown hash algo %d",
				dname_to_string(domain_dname(zone->apex), NULL), (int)i,
				rdata_atom_data(rr->rdatas[0])[0]);
			continue;
		}
		if(rdata_atom_data(rr->rdatas[1])[0] != 0) {
			/* draft-nsec3-09: NSEC3PARAM records with flags
			   field value other than zero MUST be ignored. */
			continue;
		}
		/* check hash of apex -> NSEC3 with soa bit on */
		hashed_apex = nsec3_hash_dname_param(tmpregion,
			zone, domain_dname(zone->apex), &paramset->rrs[i]);
		domain = domain_table_find(namedb->domains, hashed_apex);
		if(!domain) {
			log_msg(LOG_ERR, "%s NSEC3PARAM entry %d has no hash(apex).",
				dname_to_string(domain_dname(zone->apex), NULL), (int)i);
			log_msg(LOG_ERR, "hash(apex)= %s",
				dname_to_string(hashed_apex, NULL));
			continue;
		}
		nsec3_rrset = domain_find_rrset(domain, zone, TYPE_NSEC3);
		if(!nsec3_rrset) {
			log_msg(LOG_ERR, "%s NSEC3PARAM entry %d: hash(apex) has no NSEC3 RRset",
				dname_to_string(domain_dname(zone->apex), NULL), (int)i);
			continue;
		}
		detect_nsec3_params(rr, &salt1, &saltlen1, &iter1);
		/* find SOA bit enabled nsec3, with the same settings */
		for(j=0; j < nsec3_rrset->rr_count; j++) {
			const unsigned char *salt2;
			int saltlen2, iter2;
			if(!nsec3_has_soa(&nsec3_rrset->rrs[j]))
				continue;
			/* check params OK. Ignores the optout bit. */
			detect_nsec3_params(&nsec3_rrset->rrs[j],
				&salt2, &saltlen2, &iter2);
			if(saltlen1 == saltlen2 && iter1 == iter2 &&
				rdata_atom_data(rr->rdatas[0])[0] == /* algo */
				rdata_atom_data(nsec3_rrset->rrs[j].rdatas[0])[0]
				&& memcmp(salt1, salt2, saltlen1) == 0) {
				/* found it */
				DEBUG(DEBUG_QUERY, 1, (LOG_INFO,
					"detected NSEC3 for zone %s saltlen=%d iter=%d",
					dname_to_string(domain_dname(
					zone->apex),0), saltlen2, iter2));
				region_destroy(tmpregion);
				return &nsec3_rrset->rrs[j];
			}
		}
		log_msg(LOG_ERR, "%s NSEC3PARAM entry %d: hash(apex) no NSEC3 with SOAbit",
			dname_to_string(domain_dname(zone->apex), NULL), (int)i);
	}
	region_destroy(tmpregion);
	return NULL;
}

/* check that the rrset has an NSEC3 that uses the same parameters as the
   zone is using. Pass NSEC3 rrset, and zone must have nsec3_rrset set.
   if you pass NULL then 0 is returned. */
static int
nsec3_rrset_params_ok(rr_type* base, rrset_type* rrset)
{
	rdata_atom_type* prd;
	size_t i;
	if(!rrset)
		return 0; /* without rrset, no matching params either */
	assert(rrset && rrset->zone && (base || rrset->zone->nsec3_soa_rr));
	if(!base)
		base = rrset->zone->nsec3_soa_rr;
	prd = base->rdatas;
	for(i=0; i < rrset->rr_count; ++i) {
		rdata_atom_type* rd = rrset->rrs[i].rdatas;
		assert(rrset->rrs[i].type == TYPE_NSEC3);
		if(rdata_atom_data(rd[0])[0] ==
			rdata_atom_data(prd[0])[0] && /* hash algo */
		   rdata_atom_data(rd[2])[0] ==
			rdata_atom_data(prd[2])[0] && /* iterations 0 */
		   rdata_atom_data(rd[2])[1] ==
			rdata_atom_data(prd[2])[1] && /* iterations 1 */
		   rdata_atom_data(rd[3])[0] ==
			rdata_atom_data(prd[3])[0] && /* salt length */
		   memcmp(rdata_atom_data(rd[3])+1,
			rdata_atom_data(prd[3])+1, rdata_atom_data(rd[3])[0])
			== 0 )
		{
			/* this NSEC3 matches nsec3 parameters from zone */
			return 1;
		}
	}
	return 0;
}

#ifdef FULL_PREHASH

int
nsec3_find_cover(namedb_type* db, zone_type* zone,
	const dname_type* hashname, domain_type** result)
{
	rrset_type *rrset;
	domain_type *walk;
	domain_type *closest_match;
	domain_type *closest_encloser;
	int exact;

	assert(result);
	assert(zone->nsec3_soa_rr);

	exact = domain_table_search(
		db->domains, hashname, &closest_match, &closest_encloser);
	/* exact match of hashed domain name + it has an NSEC3? */
	if(exact &&
	   nsec3_rrset_params_ok(NULL,
	   	domain_find_rrset(closest_encloser, zone, TYPE_NSEC3))) {
		*result = closest_encloser;
		assert(*result != 0);
		return 1;
	}

	/* find covering NSEC3 record, lexicographically before the closest match */
	/* use nsec3_lookup to jumpstart the search */
	walk = closest_match->nsec3_lookup;
	rrset = 0;
	while(walk && dname_is_subdomain(domain_dname(walk), domain_dname(zone->apex)))
	{
		if(nsec3_rrset_params_ok(NULL,
			domain_find_rrset(walk, zone, TYPE_NSEC3))) {
			/* this rrset is OK NSEC3, exit while */
			rrset = domain_find_rrset(walk, zone, TYPE_NSEC3);
			break;
		}
		walk = domain_previous(walk);
	}
	if(rrset)
		*result = walk;
	else 	{
		/*
		 * There are no NSEC3s before the closest match.
		 * so the hash name is before the first NSEC3 record in the zone.
		 * use last NSEC3, which covers the wraparound in hash space
		 *
		 * Since the zone has an NSEC3 with the SOA bit set for NSEC3 to turn on,
		 * there is also a last nsec3, so find_cover always assigns *result!=0.
		 */
		*result = zone->nsec3_last;
	}
	assert(*result != 0);
	return 0;
}

#else

int
nsec3_find_cover(namedb_type* ATTR_UNUSED(db), zone_type* zone,
	const dname_type* hashname, struct nsec3_domain **result)
{
	rbnode_t *node;
	int exact;

	assert(result);
	if (!zone->nsec3_domains)
		return 0;

	exact = rbtree_find_less_equal(zone->nsec3_domains, hashname, &node);
	if (!node) {
		exact = 0;
		node = rbtree_last(zone->nsec3_domains);
	}

	while (node != RBTREE_NULL) {
		struct rrset *nsec3_rrset;
		struct nsec3_domain *nsec3_domain =
			(struct nsec3_domain *) node;
		nsec3_rrset = domain_find_rrset(nsec3_domain->nsec3_domain,
			zone, TYPE_NSEC3);
		if (!nsec3_rrset) {
			/*
			 * RRset in zone->nsec3_domains whose type != NSEC3
			 * If we get here, something is seriously wrong!
			 */
			return 0;
		}
		if (nsec3_rrset_params_ok(NULL, nsec3_rrset) != 0) {
			*result = nsec3_domain;
			return exact;
                }
		exact = 0; /* No match, so we're looking for closest match */
		node = rbtree_previous(node);
	}
	/*
	 * If we reach this point, *result == NULL.  This should
	 * never happen since the zone should have one NSEC3 record with
	 * the SOA bit set, which matches a NSEC3PARAM RR in the zone.
	 */
	return exact;
}
#endif

#ifdef FULL_PREHASH
static void
prehash_domain_r(namedb_type* db, zone_type* zone,
	domain_type* domain, region_type* region)
{
	int exact;
	const dname_type *wcard, *wcard_child, *hashname;
	domain_type* result = 0;
	if(!zone->nsec3_soa_rr)
	{
		/* set to 0 (in case NSEC3 removed after an update) */
		domain->nsec3_is_exact = 0;
		domain->nsec3_cover = NULL;
		domain->nsec3_wcard_child_cover = NULL;
		return;
	}

	hashname = nsec3_hash_dname(region, zone, domain_dname(domain));
	exact = nsec3_find_cover(db, zone, hashname, &result);
	domain->nsec3_cover = result;
	if(exact)
		domain->nsec3_is_exact = 1;
	else	domain->nsec3_is_exact = 0;

	/* find cover for *.domain for wildcard denial */
	wcard = dname_parse(region, "*");
	wcard_child = dname_concatenate(region, wcard, domain_dname(domain));
	hashname = nsec3_hash_dname(region, zone, wcard_child);
	exact = nsec3_find_cover(db, zone, hashname, &result);
	domain->nsec3_wcard_child_cover = result;

	if(exact && !domain_wildcard_child(domain))
	{
		/* We found an exact match for the *.domain NSEC3 hash,
		 * but the domain wildcard child (*.domain) does not exist.
		 * Thus there is a hash collision. It will cause servfail
		 * for NXdomain queries below this domain.
		 */
		log_msg(LOG_WARNING, "prehash: collision of wildcard "
			"denial for %s. Sign zone with different salt "
			"to remove collision.",
			dname_to_string(domain_dname(domain),0));
	}
}

#else

static void
prehash_domain_r(namedb_type* db, zone_type* zone,
	domain_type* domain, region_type* region)
{
	int exact;
	const dname_type *hashname;
	struct nsec3_domain* result = NULL;

	domain->nsec3_cover = NULL;
	hashname = nsec3_hash_dname(region, zone, domain_dname(domain));
	exact = nsec3_find_cover(db, zone, hashname, &result);
	if (result && exact)
    {
		result->covers = domain;
		domain->nsec3_cover = result->nsec3_domain;
	}
	return;
}
#endif

static void
prehash_domain(namedb_type* db, zone_type* zone,
	domain_type* domain, region_type* region)
{
    prehash_domain_r(db, zone, domain, region);
}

#ifdef FULL_PREHASH
static void
prehash_ds(namedb_type* db, zone_type* zone,
	domain_type* domain, region_type* region)
{
	domain_type* result = 0;
	const dname_type* hashname;
	int exact;

	if(!zone->nsec3_soa_rr) {
		domain->nsec3_ds_parent_is_exact = 0;
		domain->nsec3_ds_parent_cover = NULL;
		return;
	}

	/* hash again, other zone could have different hash parameters */
	hashname = nsec3_hash_dname(region, zone, domain_dname(domain));
	exact = nsec3_find_cover(db, zone, hashname, &result);
	if(exact)
		domain->nsec3_ds_parent_is_exact = 1;
	else 	domain->nsec3_ds_parent_is_exact = 0;
	domain->nsec3_ds_parent_cover = result;
}
#endif

#ifndef FULL_PREHASH
struct domain *
find_last_nsec3_domain(struct zone *zone)
{
	rbnode_t *node;
	if (zone->nsec3_domains == NULL) {
		return NULL;
	}
	node = rbtree_last(zone->nsec3_domains);
        if (node == RBTREE_NULL) {
                return NULL;
        }
	return ((struct nsec3_domain *) node)->nsec3_domain;
}

void
prehash_zone_incremental(struct namedb *db, struct zone *zone)
{
	region_type *temp_region;
	rbnode_t *node;
	/* find zone NSEC3PARAM settings */
	zone->nsec3_soa_rr = find_zone_nsec3(db, zone);
        if (zone->nsec3_soa_rr == NULL) {
                zone->nsec3_last = NULL;
                return;
        }
        if (db->nsec3_mod_domains == NULL) {
                return;
        }
	zone->nsec3_last = find_last_nsec3_domain(zone);
        temp_region = region_create(xalloc, free);
	node = rbtree_first(db->nsec3_mod_domains);
	while (node != RBTREE_NULL) {
		struct nsec3_mod_domain *nsec3_mod_domain =
			(struct nsec3_mod_domain *) node;
		struct domain *walk = nsec3_mod_domain->domain;
		struct domain *domain_zone_apex;

		if (!walk ||
			(dname_is_subdomain(domain_dname(walk),
				domain_dname(zone->apex)) == 0)) {
			node = rbtree_next(node);
			continue;
		}
		if (walk->nsec3_cover != NULL) {
			node = rbtree_next(node);
			continue;
		}
		/* Empty Terminal */
		if (!walk->is_existing) {
			walk->nsec3_cover = NULL;
			node = rbtree_next(node);
			continue;
		}

		/*
		 * Don't hash NSEC3 only nodes, unless possibly
		 * part of a weird case where node is empty nonterminal
		 * requiring NSEC3 but node name also is the hashed
		 * node name of another node requiring NSEC3.
		 * NSEC3 Empty Nonterminal with NSEC3 RRset present.
		 */
		if (domain_has_only_NSEC3(walk, zone) != 0) {
			struct domain *next_domain = domain_next(walk);
			if ((next_domain == NULL) ||
			    (next_domain->parent != walk)) {
				walk->nsec3_cover = NULL;
				node = rbtree_next(node);
				continue;
			}
		}

		/*
		 * Identify domain nodes that belong to the zone
		 * which are not glue records.  What if you hit a
		 * record that's in two zones but which has no
		 * cut point between the zones. Not valid but
		 * someone is gonna try it sometime.
		 * This implementation doesn't link an NSEC3
		 * record to the domain.
		 */
		domain_zone_apex = domain_find_zone_apex(walk);
		if ((domain_zone_apex != NULL) &&
		    (domain_zone_apex == zone->apex) &&
		    (domain_is_glue(walk, zone) == 0)) {

                        prehash_domain(db, zone, walk, temp_region);
			region_free_all(temp_region);
		}

		node = rbtree_next(node);
	}
	namedb_nsec3_mod_domains_destroy(db);
	region_destroy(temp_region);
}

void
prehash_zone(struct namedb* db, struct zone* zone)
{
	domain_type *walk;
	domain_type *last_nsec3_node;
	region_type *temp_region;
	assert(db && zone);

	/* find zone settings */
	zone->nsec3_soa_rr = find_zone_nsec3(db, zone);
	if(!zone->nsec3_soa_rr) {
		zone->nsec3_last = NULL;
		return;
	}
	temp_region = region_create(xalloc, free);

	/* go through entire zone and setup nsec3_lookup speedup */
	walk = zone->apex;
	last_nsec3_node = NULL;
	/* since we walk in sorted order, we pass all NSEC3s in sorted
	   order and we can set the lookup ptrs */
	while(walk && dname_is_subdomain(
		domain_dname(walk), domain_dname(zone->apex)))
	{
		struct domain *domain_zone_apex;

		if (walk->nsec3_cover != NULL) {
			walk = domain_next(walk);
			continue;
		}
		/* Empty Terminal */
		if (walk->is_existing == 0) {
			walk->nsec3_cover = NULL;
			walk = domain_next(walk);
			continue;
		}

		/*
		 * Don't hash NSEC3 only nodes, unless possibly
		 * part of a weird case where node is empty nonterminal
		 * requiring NSEC3 but node name also is the hashed
		 * node name of another node requiring NSEC3.
		 * NSEC3 Empty Nonterminal with NSEC3 RRset present.
		 */
		if (domain_has_only_NSEC3(walk, zone)) {
			struct domain *next_domain = domain_next(walk);
			if ((next_domain == NULL) ||
			    (next_domain->parent != walk)) {
				walk->nsec3_cover = NULL;
				walk = domain_next(walk);
				continue;
			}
		}

		/*
		 * Identify domain nodes that belong to the zone
		 * which are not glue records.  What if you hit a
		 * record that's in two zones but which has no
		 * cut point between the zones. Not valid but
		 * someone is gonna try it sometime.
		 * This implementation doesn't link an NSEC3
		 * record to the domain.
		 */
		domain_zone_apex = domain_find_zone_apex(walk);
		if ((domain_zone_apex != NULL) &&
		    (domain_zone_apex == zone->apex) &&
		    (domain_is_glue(walk, zone) == 0))
		{
			prehash_domain(db, zone, walk, temp_region);
			region_free_all(temp_region);
		}
		walk = domain_next(walk);
	}
	region_destroy(temp_region);
}

#else

static void
prehash_zone(struct namedb* db, struct zone* zone)
{
	domain_type *walk;
	domain_type *last_nsec3_node;
	region_type *temp_region;
	assert(db && zone);

	/* find zone settings */
	zone->nsec3_soa_rr = find_zone_nsec3(db, zone);
	if(!zone->nsec3_soa_rr) {
		zone->nsec3_last = NULL;
		return;
	}
	temp_region = region_create(xalloc, free);

	/* go through entire zone and setup nsec3_lookup speedup */
	walk = zone->apex;
	last_nsec3_node = NULL;
	/* since we walk in sorted order, we pass all NSEC3s in sorted
	   order and we can set the lookup ptrs */
	while(walk && dname_is_subdomain(
		domain_dname(walk), domain_dname(zone->apex)))
	{
		zone_type* z = domain_find_zone(walk);
		if(z && z==zone)
		{
			if(domain_find_rrset(walk, zone, TYPE_NSEC3))
				last_nsec3_node = walk;
			walk->nsec3_lookup = last_nsec3_node;
		}
		walk = domain_next(walk);
	}
	zone->nsec3_last = last_nsec3_node;

	/* go through entire zone */
	walk = zone->apex;
	while(walk && dname_is_subdomain(
		domain_dname(walk), domain_dname(zone->apex)))
	{
		zone_type* z;
		if(!walk->is_existing && domain_has_only_NSEC3(walk, zone)) {
			walk->nsec3_cover = NULL;
			walk->nsec3_wcard_child_cover = NULL;
			walk = domain_next(walk);
			continue;
		}
		z = domain_find_zone(walk);
		if(z && z==zone && !domain_is_glue(walk, zone))
		{
			prehash_domain(db, zone, walk, temp_region);
			region_free_all(temp_region);
		}
		/* prehash the DS (parent zone) */
		if(domain_find_rrset(walk, zone, TYPE_DS) ||
			(domain_find_rrset(walk, zone, TYPE_NS) &&
			 walk != zone->apex))
		{
			assert(walk != zone->apex /* DS must be above zone cut */);
			prehash_ds(db, zone, walk, temp_region);
			region_free_all(temp_region);
		}
		walk = domain_next(walk);
	}
	region_destroy(temp_region);
}
#endif

void
prehash(struct namedb* db, int updated_only)
{
	zone_type *z;
	time_t end, start = time(NULL);
	int count = 0;
	for(z = db->zones; z; z = z->next)
	{
		if(!updated_only || z->updated) {
			prehash_zone(db, z);
			if(z->nsec3_soa_rr)
				count++;
		}
	}
	end = time(NULL);
	if(count > 0)
		VERBOSITY(1, (LOG_INFO, "nsec3-prepare took %lld "
		"seconds for %d zones.", (long long)(end-start), count));
}


#ifndef FULL_PREHASH
static void
nsec3_hash_and_find_cover(struct region *region,
	struct namedb *db, const struct dname *domain_dname,
	struct zone *zone, int *exact, struct domain **result)
{
	dname_type const *hash_dname;
	struct nsec3_domain *nsec3_domain;

	*result = NULL;
	*exact = 0;
	hash_dname = nsec3_hash_dname(region, zone, domain_dname);
	*exact = nsec3_find_cover(db, zone, hash_dname, &nsec3_domain);
        if (nsec3_domain != NULL) {
                *result = nsec3_domain->nsec3_domain;
        }
        return;
}

static void
nsec3_hash_and_find_wild_cover(struct region *region,
	struct namedb *db, struct domain *domain,
	struct zone *zone, int *exact, struct domain **result)
{
	struct dname const *wcard_child;
	/* find cover for *.domain for wildcard denial */
	(void) dname_make_wildcard(region, domain_dname(domain),
		&wcard_child);
        nsec3_hash_and_find_cover(region, db, wcard_child, zone, exact,
		result);
	if ((*exact != 0) &&
		(domain_wildcard_child(domain) == NULL)) {
		/* We found an exact match for the *.domain NSEC3 hash,
		 * but the domain wildcard child (*.domain) does not exist.
		 * Thus there is a hash collision. It will cause servfail
		 * for NXdomain queries below this domain.
		 */
		log_msg(LOG_WARNING,
			"collision of wildcard denial for %s. "
			"Sign zone with different salt to remove collision.",
			dname_to_string(domain_dname(domain), NULL));
	}
}
#endif


/* add the NSEC3 rrset to the query answer at the given domain */
static void
nsec3_add_rrset(struct query *query, struct answer *answer,
	rr_section_type section, struct domain* domain)
{
	if(domain) {
		rrset_type* rrset = domain_find_rrset(domain, query->zone, TYPE_NSEC3);
		if(rrset)
			answer_add_rrset(answer, section, domain, rrset);
	}
}

/* this routine does hashing at query-time. slow. */
static void
nsec3_add_nonexist_proof(struct query *query, struct answer *answer,
        struct domain *encloser, struct namedb* db, const dname_type* qname)
{
	const dname_type *to_prove;
#ifdef FULL_PREHASH
	const dname_type *hashed;
#else
	int exact = 0;
#endif
	domain_type *cover = NULL;
	assert(encloser);
	/* if query=a.b.c.d encloser=c.d. then proof needed for b.c.d. */
	/* if query=a.b.c.d encloser=*.c.d. then proof needed for b.c.d. */
	to_prove = dname_partial_copy(query->region, qname,
		dname_label_match_count(qname, domain_dname(encloser))+1);
	/* generate proof that one label below closest encloser does not exist */
#ifdef FULL_PREHASH
	hashed = nsec3_hash_dname(query->region, query->zone, to_prove);
	if(nsec3_find_cover(db, query->zone, hashed, &cover))
#else
	nsec3_hash_and_find_cover(query->region, db, to_prove, query->zone,
		&exact, &cover);
	if (exact)
#endif
	{
		/* exact match, hash collision */
		/* the hashed name of the query corresponds to an existing name. */
		log_msg(LOG_ERR, "nsec3 hash collision for name=%s",
			dname_to_string(to_prove, NULL));
		RCODE_SET(query->packet, RCODE_SERVFAIL);
		return;
	}
	else if (cover) {
		/* cover proves the qname does not exist */
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION, cover);
	}
}

static void
nsec3_add_closest_encloser_proof(
	struct query *query, struct answer *answer,
	struct domain *closest_encloser, struct namedb* db,
	const dname_type* qname)
{
	if(!closest_encloser)
		return;
	/* prove that below closest encloser nothing exists */
	nsec3_add_nonexist_proof(query, answer, closest_encloser, db, qname);
	/* proof that closest encloser exists */
#ifdef FULL_PREHASH
	if(closest_encloser->nsec3_is_exact)
#else
	if(closest_encloser->nsec3_cover)
#endif
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
			closest_encloser->nsec3_cover);
}


void
nsec3_answer_wildcard(struct query *query, struct answer *answer,
        struct domain *wildcard, struct namedb* db, const dname_type* qname)
{
	if(!wildcard)
		return;
	if(!query->zone->nsec3_soa_rr)
		return;
	nsec3_add_nonexist_proof(query, answer, wildcard, db, qname);
}


static void
nsec3_add_ds_proof(struct query *query, struct answer *answer,
	struct domain *domain, int delegpt)
{
#ifndef FULL_PREHASH
	struct domain * ds_parent_cover = NULL;
	int exact = 0;
#endif
	/* assert we are above the zone cut */
	assert(domain != query->zone->apex);

#ifdef FULL_PREHASH
	if(domain->nsec3_ds_parent_is_exact) {
		/* use NSEC3 record from above the zone cut. */
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
			domain->nsec3_ds_parent_cover);
	} else if (!delegpt && domain->nsec3_is_exact) {
#else
	nsec3_hash_and_find_cover(query->region, NULL, domain_dname(domain),
		query->zone, &exact, &ds_parent_cover);
	if (exact) {
		/* use NSEC3 record from above the zone cut. */
		if (ds_parent_cover) {
			nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
				ds_parent_cover);
		}
	} else if (!delegpt && domain->nsec3_cover) {
#endif
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
			domain->nsec3_cover);
	} else {
		/* prove closest provable encloser */
		domain_type* par = domain->parent;
		domain_type* prev_par = NULL;
		assert(par); /* must be provable, thus there must be a parent */

#ifdef FULL_PREHASH
		while(!par->nsec3_is_exact)
#else
		while(!par->nsec3_cover)
#endif
		{
			prev_par = par;
			par = par->parent;
			assert(par); /* parent zone apex must be provable, thus this ends */
		}
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
			par->nsec3_cover);
		/* we took several steps to go to the provable parent, so
		   the one below it has no exact nsec3, disprove it.
		   disprove is easy, it has a prehashed cover ptr. */
		if(prev_par) {
#ifdef FULL_PREHASH
			assert(prev_par != domain && !prev_par->nsec3_is_exact);
			nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
				prev_par->nsec3_cover);
#else
			struct domain *prev_parent_cover = NULL;
			nsec3_hash_and_find_cover(query->region, NULL,
				domain_dname(prev_par), query->zone,
				&exact, &prev_parent_cover);
			if (prev_parent_cover) {
				nsec3_add_rrset(query, answer,
					AUTHORITY_SECTION, prev_parent_cover);
			}
#endif
		}

		/* use NSEC3 record from above the zone cut. */
		/* add optout range from parent zone */
		/* note: no check of optout bit, resolver checks it */
#ifdef FULL_PREHASH
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
			domain->nsec3_ds_parent_cover);
#else
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
			ds_parent_cover);
#endif
	}
}


void
nsec3_answer_nodata(struct query *query, struct answer *answer,
	struct domain *original)
{
	if(!query->zone->nsec3_soa_rr)
		return;

	/* nodata when asking for secure delegation */
	if(query->qtype == TYPE_DS)
	{
		if(original == query->zone->apex) {
			/* DS at zone apex, but server not authoritative for parent zone */
			/* so answer at the child zone level */
#ifdef FULL_PREHASH
			if(original->nsec3_is_exact)
#else
			if(original->nsec3_cover)
#endif
				nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
					original->nsec3_cover);
			return;
		}
		/* query->zone must be the parent zone */
		nsec3_add_ds_proof(query, answer, original, 0);
	}
	/* the nodata is result from a wildcard match */
	else if (original==original->wildcard_child_closest_match
		&& label_is_wildcard(dname_name(domain_dname(original)))) {
#ifndef FULL_PREHASH
		struct domain* original_cover;
		int exact;
#endif
		/* denial for wildcard is already there */

		/* add parent proof to have a closest encloser proof for wildcard parent */
		/* in other words: nsec3 matching closest encloser */
#ifdef FULL_PREHASH
		if(original->parent && original->parent->nsec3_is_exact)
#else
		if(original->parent && original->parent->nsec3_cover)
#endif
			nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
				original->parent->nsec3_cover);

		/* proof for wildcard itself */
		/* in other words: nsec3 matching source of synthesis */
#ifdef FULL_PREHASH
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
			original->nsec3_cover);
#else
		original_cover = original->nsec3_cover;
		if (!original_cover) { /* not exact */
			nsec3_hash_and_find_cover(query->region, NULL,
				domain_dname(original), query->zone,
				&exact, &original_cover);
                }
		if (original_cover) {
	                nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
				original_cover);
		}
#endif

	}
	else { /* add nsec3 to prove rrset does not exist */
#ifdef FULL_PREHASH
		if(original->nsec3_is_exact)
#else
		if (original->nsec3_cover != NULL)
#endif
			nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
				original->nsec3_cover);
	}
}

void
nsec3_answer_delegation(struct query *query, struct answer *answer)
{
	if(!query->zone->nsec3_soa_rr)
		return;
	nsec3_add_ds_proof(query, answer, query->delegation_domain, 1);
}

int
domain_has_only_NSEC3(struct domain* domain, struct zone* zone)
{
	/* check for only NSEC3/RRSIG */
	rrset_type* rrset = domain->rrsets;
	int nsec3_seen = 0;
	while(rrset)
	{
		if(!zone || rrset->zone == zone)
		{
			if(rrset->rrs[0].type == TYPE_NSEC3)
				nsec3_seen = 1;
			else if(rrset->rrs[0].type != TYPE_RRSIG)
				return 0;
		}
		rrset = rrset->next;
	}
	return nsec3_seen;
}

void
nsec3_answer_authoritative(struct domain** match, struct query *query,
	struct answer *answer, struct domain* closest_encloser,
	struct namedb* db, const dname_type* qname)
{
#ifndef FULL_PREHASH
	struct domain *cover_domain = NULL;
	int exact = 0;
#endif

	if(!query->zone->nsec3_soa_rr)
		return;
	assert(match);
	/* there is a match, this has 1 RRset, which is NSEC3, but qtype is not. */
        /* !is_existing: no RR types exist at the QNAME, nor at any descendant of QNAME */
	if(*match && !(*match)->is_existing &&
#if 0
		query->qtype != TYPE_NSEC3 &&
#endif
		domain_has_only_NSEC3(*match, query->zone))
	{
		/* act as if the NSEC3 domain did not exist, name error */
		*match = 0;
		/* all nsec3s are directly below the apex, that is closest encloser */
#ifdef FULL_PREHASH
		if(query->zone->apex->nsec3_is_exact)
#else
		if(query->zone->apex->nsec3_cover)
#endif
			nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
				query->zone->apex->nsec3_cover);

		/* disprove the nsec3 record. */
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
			closest_encloser->nsec3_cover);
		/* disprove a wildcard */
#ifdef FULL_PREHASH
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
            query->zone->apex->nsec3_wcard_child_cover);
#else
		cover_domain = NULL;
		nsec3_hash_and_find_cover(query->region, db,
			domain_dname(closest_encloser),
			query->zone, &exact, &cover_domain);
		if (cover_domain)
	                nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
				cover_domain);
#endif
		if (domain_wildcard_child(query->zone->apex)) {
			/* wildcard exists below the domain */
			/* wildcard and nsec3 domain clash. server failure. */
			RCODE_SET(query->packet, RCODE_SERVFAIL);
		}
		return;
	}
	else if(*match && (*match)->is_existing &&
#if 0
		query->qtype != TYPE_NSEC3 &&
#endif
		domain_has_only_NSEC3(*match, query->zone))
	{
		/* this looks like a NSEC3 domain, but is actually an empty non-terminal. */
		nsec3_answer_nodata(query, answer, *match);
		return;
	}
	if(!*match) {
		/* name error, domain does not exist */
		nsec3_add_closest_encloser_proof(query, answer,
			closest_encloser, db, qname);
#ifdef FULL_PREHASH
		nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
			closest_encloser->nsec3_wcard_child_cover);
#else
		cover_domain = NULL;
		nsec3_hash_and_find_wild_cover(query->region, db,
			closest_encloser, query->zone, &exact, &cover_domain);
		if (cover_domain)
			nsec3_add_rrset(query, answer, AUTHORITY_SECTION,
				cover_domain);
#endif
	}
}

#endif /* NSEC3 */