/*
 * validator/val_utils.c - validator utility functions.
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * This file contains helper functions for the validator module.
 */
#include "config.h"
#include "validator/val_utils.h"
#include "validator/validator.h"
#include "validator/val_kentry.h"
#include "validator/val_sigcrypt.h"
#include "validator/val_anchor.h"
#include "validator/val_nsec.h"
#include "validator/val_neg.h"
#include "services/cache/rrset.h"
#include "services/cache/dns.h"
#include "util/data/msgreply.h"
#include "util/data/packed_rrset.h"
#include "util/data/dname.h"
#include "util/net_help.h"
#include "util/module.h"
#include "util/regional.h"
#include "util/config_file.h"
#include "sldns/wire2str.h"
#include "sldns/parseutil.h"

enum val_classification 
val_classify_response(uint16_t query_flags, struct query_info* origqinf,
	struct query_info* qinf, struct reply_info* rep, size_t skip)
{
	int rcode = (int)FLAGS_GET_RCODE(rep->flags);
	size_t i;

	/* Normal Name Error's are easy to detect -- but don't mistake a CNAME
	 * chain ending in NXDOMAIN. */
	if(rcode == LDNS_RCODE_NXDOMAIN && rep->an_numrrsets == 0)
		return VAL_CLASS_NAMEERROR;

	/* check for referral: nonRD query and it looks like a nodata */
	if(!(query_flags&BIT_RD) && rep->an_numrrsets == 0 &&
		rcode == LDNS_RCODE_NOERROR) {
		/* SOA record in auth indicates it is NODATA instead.
		 * All validation requiring NODATA messages have SOA in 
		 * authority section. */
		/* uses fact that answer section is empty */
		int saw_ns = 0;
		for(i=0; i<rep->ns_numrrsets; i++) {
			if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_SOA)
				return VAL_CLASS_NODATA;
			if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_DS)
				return VAL_CLASS_REFERRAL;
			if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NS)
				saw_ns = 1;
		}
		return saw_ns?VAL_CLASS_REFERRAL:VAL_CLASS_NODATA;
	}
	/* root referral where NS set is in the answer section */
	if(!(query_flags&BIT_RD) && rep->ns_numrrsets == 0 &&
		rep->an_numrrsets == 1 && rcode == LDNS_RCODE_NOERROR &&
		ntohs(rep->rrsets[0]->rk.type) == LDNS_RR_TYPE_NS &&
		query_dname_compare(rep->rrsets[0]->rk.dname, 
			origqinf->qname) != 0)
		return VAL_CLASS_REFERRAL;

	/* dump bad messages */
	if(rcode != LDNS_RCODE_NOERROR && rcode != LDNS_RCODE_NXDOMAIN)
		return VAL_CLASS_UNKNOWN;
	/* next check if the skip into the answer section shows no answer */
	if(skip>0 && rep->an_numrrsets <= skip)
		return VAL_CLASS_CNAMENOANSWER;

	/* Next is NODATA */
	if(rcode == LDNS_RCODE_NOERROR && rep->an_numrrsets == 0)
		return VAL_CLASS_NODATA;
	
	/* We distinguish between CNAME response and other positive/negative
	 * responses because CNAME answers require extra processing. */

	/* We distinguish between ANY and CNAME or POSITIVE because 
	 * ANY responses are validated differently. */
	if(rcode == LDNS_RCODE_NOERROR && qinf->qtype == LDNS_RR_TYPE_ANY)
		return VAL_CLASS_ANY;
	
	/* Note that DNAMEs will be ignored here, unless qtype=DNAME. Unless
	 * qtype=CNAME, this will yield a CNAME response. */
	for(i=skip; i<rep->an_numrrsets; i++) {
		if(rcode == LDNS_RCODE_NOERROR &&
			ntohs(rep->rrsets[i]->rk.type) == qinf->qtype)
			return VAL_CLASS_POSITIVE;
		if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_CNAME)
			return VAL_CLASS_CNAME;
	}
	log_dns_msg("validator: error. failed to classify response message: ",
		qinf, rep);
	return VAL_CLASS_UNKNOWN;
}

/** Get signer name from RRSIG */
static void
rrsig_get_signer(uint8_t* data, size_t len, uint8_t** sname, size_t* slen)
{
	/* RRSIG rdata is not allowed to be compressed, it is stored
	 * uncompressed in memory as well, so return a ptr to the name */
	if(len < 21) {
		/* too short RRSig:
		 * short, byte, byte, long, long, long, short, "." is
		 * 2	1	1	4	4  4	2	1 = 19
		 * 			and a skip of 18 bytes to the name.
		 * +2 for the rdatalen is 21 bytes len for root label */
		*sname = NULL;
		*slen = 0;
		return;
	}
	data += 20; /* skip the fixed size bits */
	len -= 20;
	*slen = dname_valid(data, len);
	if(!*slen) {
		/* bad dname in this rrsig. */
		*sname = NULL;
		return;
	}
	*sname = data;
}

void 
val_find_rrset_signer(struct ub_packed_rrset_key* rrset, uint8_t** sname,
	size_t* slen)
{
	struct packed_rrset_data* d = (struct packed_rrset_data*)
		rrset->entry.data;
	/* return signer for first signature, or NULL */
	if(d->rrsig_count == 0) {
		*sname = NULL;
		*slen = 0;
		return;
	}
	/* get rrsig signer name out of the signature */
	rrsig_get_signer(d->rr_data[d->count], d->rr_len[d->count], 
		sname, slen);
}

/**
 * Find best signer name in this set of rrsigs.
 * @param rrset: which rrsigs to look through.
 * @param qinf: the query name that needs validation.
 * @param signer_name: the best signer_name. Updated if a better one is found.
 * @param signer_len: length of signer name.
 * @param matchcount: count of current best name (starts at 0 for no match).
 * 	Updated if match is improved.
 */
static void
val_find_best_signer(struct ub_packed_rrset_key* rrset, 
	struct query_info* qinf, uint8_t** signer_name, size_t* signer_len, 
	int* matchcount)
{
	struct packed_rrset_data* d = (struct packed_rrset_data*)
		rrset->entry.data;
	uint8_t* sign;
	size_t i;
	int m;
	for(i=d->count; i<d->count+d->rrsig_count; i++) {
		sign = d->rr_data[i]+2+18;
		/* look at signatures that are valid (long enough),
		 * and have a signer name that is a superdomain of qname,
		 * and then check the number of labels in the shared topdomain
		 * improve the match if possible */
		if(d->rr_len[i] > 2+19 && /* rdata, sig + root label*/
			dname_subdomain_c(qinf->qname, sign)) {
			(void)dname_lab_cmp(qinf->qname, 
				dname_count_labels(qinf->qname), 
				sign, dname_count_labels(sign), &m);
			if(m > *matchcount) {
				*matchcount = m;
				*signer_name = sign;
				(void)dname_count_size_labels(*signer_name,
					signer_len);
			}
		}
	}
}

void 
val_find_signer(enum val_classification subtype, struct query_info* qinf, 
	struct reply_info* rep, size_t skip, uint8_t** signer_name, 
	size_t* signer_len)
{
	size_t i;
	
	if(subtype == VAL_CLASS_POSITIVE) {
		/* check for the answer rrset */
		for(i=skip; i<rep->an_numrrsets; i++) {
			if(query_dname_compare(qinf->qname, 
				rep->rrsets[i]->rk.dname) == 0) {
				val_find_rrset_signer(rep->rrsets[i], 
					signer_name, signer_len);
				return;
			}
		}
		*signer_name = NULL;
		*signer_len = 0;
	} else if(subtype == VAL_CLASS_CNAME) {
		/* check for the first signed cname/dname rrset */
		for(i=skip; i<rep->an_numrrsets; i++) {
			val_find_rrset_signer(rep->rrsets[i], 
				signer_name, signer_len);
			if(*signer_name)
				return;
			if(ntohs(rep->rrsets[i]->rk.type) != LDNS_RR_TYPE_DNAME)
				break; /* only check CNAME after a DNAME */
		}
		*signer_name = NULL;
		*signer_len = 0;
	} else if(subtype == VAL_CLASS_NAMEERROR 
		|| subtype == VAL_CLASS_NODATA) {
		/*Check to see if the AUTH section NSEC record(s) have rrsigs*/
		for(i=rep->an_numrrsets; i<
			rep->an_numrrsets+rep->ns_numrrsets; i++) {
			if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NSEC
				|| ntohs(rep->rrsets[i]->rk.type) ==
				LDNS_RR_TYPE_NSEC3) {
				val_find_rrset_signer(rep->rrsets[i], 
					signer_name, signer_len);
				return;
			}
		}
	} else if(subtype == VAL_CLASS_CNAMENOANSWER) {
		/* find closest superdomain signer name in authority section
		 * NSEC and NSEC3s */
		int matchcount = 0;
		*signer_name = NULL;
		*signer_len = 0;
		for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->
			ns_numrrsets; i++) { 
			if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_NSEC
				|| ntohs(rep->rrsets[i]->rk.type) == 
				LDNS_RR_TYPE_NSEC3) {
				val_find_best_signer(rep->rrsets[i], qinf,
					signer_name, signer_len, &matchcount);
			}
		}
	} else if(subtype == VAL_CLASS_ANY) {
		/* check for one of the answer rrset that has signatures,
		 * or potentially a DNAME is in use with a different qname */
		for(i=skip; i<rep->an_numrrsets; i++) {
			if(query_dname_compare(qinf->qname, 
				rep->rrsets[i]->rk.dname) == 0) {
				val_find_rrset_signer(rep->rrsets[i], 
					signer_name, signer_len);
				if(*signer_name)
					return;
			}
		}
		/* no answer RRSIGs with qname, try a DNAME */
		if(skip < rep->an_numrrsets &&
			ntohs(rep->rrsets[skip]->rk.type) ==
			LDNS_RR_TYPE_DNAME) {
			val_find_rrset_signer(rep->rrsets[skip], 
				signer_name, signer_len);
			if(*signer_name)
				return;
		}
		*signer_name = NULL;
		*signer_len = 0;
	} else if(subtype == VAL_CLASS_REFERRAL) {
		/* find keys for the item at skip */
		if(skip < rep->rrset_count) {
			val_find_rrset_signer(rep->rrsets[skip], 
				signer_name, signer_len);
			return;
		}
		*signer_name = NULL;
		*signer_len = 0;
	} else {
		verbose(VERB_QUERY, "find_signer: could not find signer name"
			" for unknown type response");
		*signer_name = NULL;
		*signer_len = 0;
	}
}

/** return number of rrs in an rrset */
static size_t
rrset_get_count(struct ub_packed_rrset_key* rrset)
{
	struct packed_rrset_data* d = (struct packed_rrset_data*)
		rrset->entry.data;
	if(!d) return 0;
	return d->count;
}

/** return TTL of rrset */
static uint32_t
rrset_get_ttl(struct ub_packed_rrset_key* rrset)
{
	struct packed_rrset_data* d = (struct packed_rrset_data*)
		rrset->entry.data;
	if(!d) return 0;
	return d->ttl;
}

enum sec_status 
val_verify_rrset(struct module_env* env, struct val_env* ve,
        struct ub_packed_rrset_key* rrset, struct ub_packed_rrset_key* keys,
	uint8_t* sigalg, char** reason, sldns_pkt_section section,
	struct module_qstate* qstate)
{
	enum sec_status sec;
	struct packed_rrset_data* d = (struct packed_rrset_data*)rrset->
		entry.data;
	if(d->security == sec_status_secure) {
		/* re-verify all other statuses, because keyset may change*/
		log_nametypeclass(VERB_ALGO, "verify rrset cached", 
			rrset->rk.dname, ntohs(rrset->rk.type), 
			ntohs(rrset->rk.rrset_class));
		return d->security;
	}
	/* check in the cache if verification has already been done */
	rrset_check_sec_status(env->rrset_cache, rrset, *env->now);
	if(d->security == sec_status_secure) {
		log_nametypeclass(VERB_ALGO, "verify rrset from cache", 
			rrset->rk.dname, ntohs(rrset->rk.type), 
			ntohs(rrset->rk.rrset_class));
		return d->security;
	}
	log_nametypeclass(VERB_ALGO, "verify rrset", rrset->rk.dname,
		ntohs(rrset->rk.type), ntohs(rrset->rk.rrset_class));
	sec = dnskeyset_verify_rrset(env, ve, rrset, keys, sigalg, reason,
		section, qstate);
	verbose(VERB_ALGO, "verify result: %s", sec_status_to_string(sec));
	regional_free_all(env->scratch);

	/* update rrset security status 
	 * only improves security status 
	 * and bogus is set only once, even if we rechecked the status */
	if(sec > d->security) {
		d->security = sec;
		if(sec == sec_status_secure)
			d->trust = rrset_trust_validated;
		else if(sec == sec_status_bogus) {
			size_t i;
			/* update ttl for rrset to fixed value. */
			d->ttl = ve->bogus_ttl;
			for(i=0; i<d->count+d->rrsig_count; i++)
				d->rr_ttl[i] = ve->bogus_ttl;
			/* leave RR specific TTL: not used for determine
			 * if RRset timed out and clients see proper value. */
			lock_basic_lock(&ve->bogus_lock);
			ve->num_rrset_bogus++;
			lock_basic_unlock(&ve->bogus_lock);
		}
		/* if status updated - store in cache for reuse */
		rrset_update_sec_status(env->rrset_cache, rrset, *env->now);
	}

	return sec;
}

enum sec_status 
val_verify_rrset_entry(struct module_env* env, struct val_env* ve,
        struct ub_packed_rrset_key* rrset, struct key_entry_key* kkey,
	char** reason, sldns_pkt_section section, struct module_qstate* qstate)
{
	/* temporary dnskey rrset-key */
	struct ub_packed_rrset_key dnskey;
	struct key_entry_data* kd = (struct key_entry_data*)kkey->entry.data;
	enum sec_status sec;
	dnskey.rk.type = htons(kd->rrset_type);
	dnskey.rk.rrset_class = htons(kkey->key_class);
	dnskey.rk.flags = 0;
	dnskey.rk.dname = kkey->name;
	dnskey.rk.dname_len = kkey->namelen;
	dnskey.entry.key = &dnskey;
	dnskey.entry.data = kd->rrset_data;
	sec = val_verify_rrset(env, ve, rrset, &dnskey, kd->algo, reason,
		section, qstate);
	return sec;
}

/** verify that a DS RR hashes to a key and that key signs the set */
static enum sec_status
verify_dnskeys_with_ds_rr(struct module_env* env, struct val_env* ve, 
	struct ub_packed_rrset_key* dnskey_rrset, 
        struct ub_packed_rrset_key* ds_rrset, size_t ds_idx, char** reason,
	struct module_qstate* qstate)
{
	enum sec_status sec = sec_status_bogus;
	size_t i, num, numchecked = 0, numhashok = 0, numsizesupp = 0;
	num = rrset_get_count(dnskey_rrset);
	for(i=0; i<num; i++) {
		/* Skip DNSKEYs that don't match the basic criteria. */
		if(ds_get_key_algo(ds_rrset, ds_idx) 
		   != dnskey_get_algo(dnskey_rrset, i)
		   || dnskey_calc_keytag(dnskey_rrset, i)
		   != ds_get_keytag(ds_rrset, ds_idx)) {
			continue;
		}
		numchecked++;
		verbose(VERB_ALGO, "attempt DS match algo %d keytag %d",
			ds_get_key_algo(ds_rrset, ds_idx),
			ds_get_keytag(ds_rrset, ds_idx));

		/* Convert the candidate DNSKEY into a hash using the 
		 * same DS hash algorithm. */
		if(!ds_digest_match_dnskey(env, dnskey_rrset, i, ds_rrset, 
			ds_idx)) {
			verbose(VERB_ALGO, "DS match attempt failed");
			continue;
		}
		numhashok++;
		if(!dnskey_size_is_supported(dnskey_rrset, i)) {
			verbose(VERB_ALGO, "DS okay but that DNSKEY size is not supported");
			numsizesupp++;
			continue;
		}
		verbose(VERB_ALGO, "DS match digest ok, trying signature");

		/* Otherwise, we have a match! Make sure that the DNSKEY 
		 * verifies *with this key*  */
		sec = dnskey_verify_rrset(env, ve, dnskey_rrset, 
			dnskey_rrset, i, reason, LDNS_SECTION_ANSWER, qstate);
		if(sec == sec_status_secure) {
			return sec;
		}
		/* If it didn't validate with the DNSKEY, try the next one! */
	}
	if(numsizesupp != 0) {
		/* there is a working DS, but that DNSKEY is not supported */
		return sec_status_insecure;
	}
	if(numchecked == 0)
		algo_needs_reason(env, ds_get_key_algo(ds_rrset, ds_idx),
			reason, "no keys have a DS");
	else if(numhashok == 0)
		*reason = "DS hash mismatches key";
	else if(!*reason)
		*reason = "keyset not secured by DNSKEY that matches DS";
	return sec_status_bogus;
}

int val_favorite_ds_algo(struct ub_packed_rrset_key* ds_rrset)
{
	size_t i, num = rrset_get_count(ds_rrset);
	int d, digest_algo = 0; /* DS digest algo 0 is not used. */
	/* find favorite algo, for now, highest number supported */
	for(i=0; i<num; i++) {
		if(!ds_digest_algo_is_supported(ds_rrset, i) ||
			!ds_key_algo_is_supported(ds_rrset, i)) {
			continue;
		}
		d = ds_get_digest_algo(ds_rrset, i);
		if(d > digest_algo)
			digest_algo = d;
	}
	return digest_algo;
}

enum sec_status 
val_verify_DNSKEY_with_DS(struct module_env* env, struct val_env* ve,
	struct ub_packed_rrset_key* dnskey_rrset,
	struct ub_packed_rrset_key* ds_rrset, uint8_t* sigalg, char** reason,
	struct module_qstate* qstate)
{
	/* as long as this is false, we can consider this DS rrset to be
	 * equivalent to no DS rrset. */
	int has_useful_ds = 0, digest_algo, alg;
	struct algo_needs needs;
	size_t i, num;
	enum sec_status sec;

	if(dnskey_rrset->rk.dname_len != ds_rrset->rk.dname_len ||
		query_dname_compare(dnskey_rrset->rk.dname, ds_rrset->rk.dname)
		!= 0) {
		verbose(VERB_QUERY, "DNSKEY RRset did not match DS RRset "
			"by name");
		*reason = "DNSKEY RRset did not match DS RRset by name";
		return sec_status_bogus;
	}

	if(sigalg) {
		/* harden against algo downgrade is enabled */
		digest_algo = val_favorite_ds_algo(ds_rrset);
		algo_needs_init_ds(&needs, ds_rrset, digest_algo, sigalg);
	} else {
		/* accept any key algo, any digest algo */
		digest_algo = -1;
	}
	num = rrset_get_count(ds_rrset);
	for(i=0; i<num; i++) {
		/* Check to see if we can understand this DS. 
		 * And check it is the strongest digest */
		if(!ds_digest_algo_is_supported(ds_rrset, i) ||
			!ds_key_algo_is_supported(ds_rrset, i) ||
			(sigalg && (ds_get_digest_algo(ds_rrset, i) != digest_algo))) {
			continue;
		}

		sec = verify_dnskeys_with_ds_rr(env, ve, dnskey_rrset,
			ds_rrset, i, reason, qstate);
		if(sec == sec_status_insecure)
			continue;

		/* Once we see a single DS with a known digestID and 
		 * algorithm, we cannot return INSECURE (with a 
		 * "null" KeyEntry). */
		has_useful_ds = 1;

		if(sec == sec_status_secure) {
			if(!sigalg || algo_needs_set_secure(&needs,
				(uint8_t)ds_get_key_algo(ds_rrset, i))) {
				verbose(VERB_ALGO, "DS matched DNSKEY.");
				if(!dnskeyset_size_is_supported(dnskey_rrset)) {
					verbose(VERB_ALGO, "DS works, but dnskeyset contain keys that are unsupported, treat as insecure");
					return sec_status_insecure;
				}
				return sec_status_secure;
			}
		} else if(sigalg && sec == sec_status_bogus) {
			algo_needs_set_bogus(&needs,
				(uint8_t)ds_get_key_algo(ds_rrset, i));
		}
	}

	/* None of the DS's worked out. */

	/* If no DSs were understandable, then this is OK. */
	if(!has_useful_ds) {
		verbose(VERB_ALGO, "No usable DS records were found -- "
			"treating as insecure.");
		return sec_status_insecure;
	}
	/* If any were understandable, then it is bad. */
	verbose(VERB_QUERY, "Failed to match any usable DS to a DNSKEY.");
	if(sigalg && (alg=algo_needs_missing(&needs)) != 0) {
		algo_needs_reason(env, alg, reason, "missing verification of "
			"DNSKEY signature");
	}
	return sec_status_bogus;
}

struct key_entry_key* 
val_verify_new_DNSKEYs(struct regional* region, struct module_env* env, 
	struct val_env* ve, struct ub_packed_rrset_key* dnskey_rrset, 
	struct ub_packed_rrset_key* ds_rrset, int downprot, char** reason,
	struct module_qstate* qstate)
{
	uint8_t sigalg[ALGO_NEEDS_MAX+1];
	enum sec_status sec = val_verify_DNSKEY_with_DS(env, ve, 
		dnskey_rrset, ds_rrset, downprot?sigalg:NULL, reason, qstate);

	if(sec == sec_status_secure) {
		return key_entry_create_rrset(region, 
			ds_rrset->rk.dname, ds_rrset->rk.dname_len,
			ntohs(ds_rrset->rk.rrset_class), dnskey_rrset,
			downprot?sigalg:NULL, *env->now);
	} else if(sec == sec_status_insecure) {
		return key_entry_create_null(region, ds_rrset->rk.dname,
			ds_rrset->rk.dname_len, 
			ntohs(ds_rrset->rk.rrset_class),
			rrset_get_ttl(ds_rrset), *env->now);
	}
	return key_entry_create_bad(region, ds_rrset->rk.dname,
		ds_rrset->rk.dname_len, ntohs(ds_rrset->rk.rrset_class),
		BOGUS_KEY_TTL, *env->now);
}

enum sec_status 
val_verify_DNSKEY_with_TA(struct module_env* env, struct val_env* ve,
	struct ub_packed_rrset_key* dnskey_rrset,
	struct ub_packed_rrset_key* ta_ds,
	struct ub_packed_rrset_key* ta_dnskey, uint8_t* sigalg, char** reason,
	struct module_qstate* qstate)
{
	/* as long as this is false, we can consider this anchor to be
	 * equivalent to no anchor. */
	int has_useful_ta = 0, digest_algo = 0, alg;
	struct algo_needs needs;
	size_t i, num;
	enum sec_status sec;

	if(ta_ds && (dnskey_rrset->rk.dname_len != ta_ds->rk.dname_len ||
		query_dname_compare(dnskey_rrset->rk.dname, ta_ds->rk.dname)
		!= 0)) {
		verbose(VERB_QUERY, "DNSKEY RRset did not match DS RRset "
			"by name");
		*reason = "DNSKEY RRset did not match DS RRset by name";
		return sec_status_bogus;
	}
	if(ta_dnskey && (dnskey_rrset->rk.dname_len != ta_dnskey->rk.dname_len
	     || query_dname_compare(dnskey_rrset->rk.dname, ta_dnskey->rk.dname)
		!= 0)) {
		verbose(VERB_QUERY, "DNSKEY RRset did not match anchor RRset "
			"by name");
		*reason = "DNSKEY RRset did not match anchor RRset by name";
		return sec_status_bogus;
	}

	if(ta_ds)
		digest_algo = val_favorite_ds_algo(ta_ds);
	if(sigalg) {
		if(ta_ds)
			algo_needs_init_ds(&needs, ta_ds, digest_algo, sigalg);
		else	memset(&needs, 0, sizeof(needs));
		if(ta_dnskey)
			algo_needs_init_dnskey_add(&needs, ta_dnskey, sigalg);
	}
	if(ta_ds) {
	    num = rrset_get_count(ta_ds);
	    for(i=0; i<num; i++) {
		/* Check to see if we can understand this DS. 
		 * And check it is the strongest digest */
		if(!ds_digest_algo_is_supported(ta_ds, i) ||
			!ds_key_algo_is_supported(ta_ds, i) ||
			ds_get_digest_algo(ta_ds, i) != digest_algo)
			continue;

		sec = verify_dnskeys_with_ds_rr(env, ve, dnskey_rrset,
			ta_ds, i, reason, qstate);
		if(sec == sec_status_insecure)
			continue;

		/* Once we see a single DS with a known digestID and 
		 * algorithm, we cannot return INSECURE (with a 
		 * "null" KeyEntry). */
		has_useful_ta = 1;

		if(sec == sec_status_secure) {
			if(!sigalg || algo_needs_set_secure(&needs,
				(uint8_t)ds_get_key_algo(ta_ds, i))) {
				verbose(VERB_ALGO, "DS matched DNSKEY.");
				if(!dnskeyset_size_is_supported(dnskey_rrset)) {
					verbose(VERB_ALGO, "trustanchor works, but dnskeyset contain keys that are unsupported, treat as insecure");
					return sec_status_insecure;
				}
				return sec_status_secure;
			}
		} else if(sigalg && sec == sec_status_bogus) {
			algo_needs_set_bogus(&needs,
				(uint8_t)ds_get_key_algo(ta_ds, i));
		}
	    }
	}

	/* None of the DS's worked out: check the DNSKEYs. */
	if(ta_dnskey) {
	    num = rrset_get_count(ta_dnskey);
	    for(i=0; i<num; i++) {
		/* Check to see if we can understand this DNSKEY */
		if(!dnskey_algo_is_supported(ta_dnskey, i))
			continue;
		if(!dnskey_size_is_supported(ta_dnskey, i))
			continue;

		/* we saw a useful TA */
		has_useful_ta = 1;

		sec = dnskey_verify_rrset(env, ve, dnskey_rrset,
			ta_dnskey, i, reason, LDNS_SECTION_ANSWER, qstate);
		if(sec == sec_status_secure) {
			if(!sigalg || algo_needs_set_secure(&needs,
				(uint8_t)dnskey_get_algo(ta_dnskey, i))) {
				verbose(VERB_ALGO, "anchor matched DNSKEY.");
				if(!dnskeyset_size_is_supported(dnskey_rrset)) {
					verbose(VERB_ALGO, "trustanchor works, but dnskeyset contain keys that are unsupported, treat as insecure");
					return sec_status_insecure;
				}
				return sec_status_secure;
			}
		} else if(sigalg && sec == sec_status_bogus) {
			algo_needs_set_bogus(&needs,
				(uint8_t)dnskey_get_algo(ta_dnskey, i));
		}
	    }
	}

	/* If no DSs were understandable, then this is OK. */
	if(!has_useful_ta) {
		verbose(VERB_ALGO, "No usable trust anchors were found -- "
			"treating as insecure.");
		return sec_status_insecure;
	}
	/* If any were understandable, then it is bad. */
	verbose(VERB_QUERY, "Failed to match any usable anchor to a DNSKEY.");
	if(sigalg && (alg=algo_needs_missing(&needs)) != 0) {
		algo_needs_reason(env, alg, reason, "missing verification of "
			"DNSKEY signature");
	}
	return sec_status_bogus;
}

struct key_entry_key* 
val_verify_new_DNSKEYs_with_ta(struct regional* region, struct module_env* env,
	struct val_env* ve, struct ub_packed_rrset_key* dnskey_rrset, 
	struct ub_packed_rrset_key* ta_ds_rrset,
	struct ub_packed_rrset_key* ta_dnskey_rrset, int downprot,
	char** reason, struct module_qstate* qstate)
{
	uint8_t sigalg[ALGO_NEEDS_MAX+1];
	enum sec_status sec = val_verify_DNSKEY_with_TA(env, ve, 
		dnskey_rrset, ta_ds_rrset, ta_dnskey_rrset,
		downprot?sigalg:NULL, reason, qstate);

	if(sec == sec_status_secure) {
		return key_entry_create_rrset(region, 
			dnskey_rrset->rk.dname, dnskey_rrset->rk.dname_len,
			ntohs(dnskey_rrset->rk.rrset_class), dnskey_rrset,
			downprot?sigalg:NULL, *env->now);
	} else if(sec == sec_status_insecure) {
		return key_entry_create_null(region, dnskey_rrset->rk.dname,
			dnskey_rrset->rk.dname_len, 
			ntohs(dnskey_rrset->rk.rrset_class),
			rrset_get_ttl(dnskey_rrset), *env->now);
	}
	return key_entry_create_bad(region, dnskey_rrset->rk.dname,
		dnskey_rrset->rk.dname_len, ntohs(dnskey_rrset->rk.rrset_class),
		BOGUS_KEY_TTL, *env->now);
}

int 
val_dsset_isusable(struct ub_packed_rrset_key* ds_rrset)
{
	size_t i;
	for(i=0; i<rrset_get_count(ds_rrset); i++) {
		if(ds_digest_algo_is_supported(ds_rrset, i) &&
			ds_key_algo_is_supported(ds_rrset, i))
			return 1;
	}
	if(verbosity < VERB_ALGO)
		return 0;
	if(rrset_get_count(ds_rrset) == 0)
		verbose(VERB_ALGO, "DS is not usable");
	else {
		/* report usability for the first DS RR */
		sldns_lookup_table *lt;
		char herr[64], aerr[64];
		lt = sldns_lookup_by_id(sldns_hashes,
			(int)ds_get_digest_algo(ds_rrset, 0));
		if(lt) snprintf(herr, sizeof(herr), "%s", lt->name);
		else snprintf(herr, sizeof(herr), "%d",
			(int)ds_get_digest_algo(ds_rrset, 0));
		lt = sldns_lookup_by_id(sldns_algorithms,
			(int)ds_get_key_algo(ds_rrset, 0));
		if(lt) snprintf(aerr, sizeof(aerr), "%s", lt->name);
		else snprintf(aerr, sizeof(aerr), "%d",
			(int)ds_get_key_algo(ds_rrset, 0));
		verbose(VERB_ALGO, "DS unsupported, hash %s %s, "
			"key algorithm %s %s", herr,
			(ds_digest_algo_is_supported(ds_rrset, 0)?
			"(supported)":"(unsupported)"), aerr, 
			(ds_key_algo_is_supported(ds_rrset, 0)?
			"(supported)":"(unsupported)"));
	}
	return 0;
}

/** get label count for a signature */
static uint8_t
rrsig_get_labcount(struct packed_rrset_data* d, size_t sig)
{
	if(d->rr_len[sig] < 2+4)
		return 0; /* bad sig length */
	return d->rr_data[sig][2+3];
}

int 
val_rrset_wildcard(struct ub_packed_rrset_key* rrset, uint8_t** wc,
	size_t* wc_len)
{
	struct packed_rrset_data* d = (struct packed_rrset_data*)rrset->
		entry.data;
	uint8_t labcount;
	int labdiff;
	uint8_t* wn;
	size_t i, wl;
	if(d->rrsig_count == 0) {
		return 1;
	}
	labcount = rrsig_get_labcount(d, d->count + 0);
	/* check rest of signatures identical */
	for(i=1; i<d->rrsig_count; i++) {
		if(labcount != rrsig_get_labcount(d, d->count + i)) {
			return 0;
		}
	}
	/* OK the rrsigs check out */
	/* if the RRSIG label count is shorter than the number of actual 
	 * labels, then this rrset was synthesized from a wildcard.
	 * Note that the RRSIG label count doesn't count the root label. */
	wn = rrset->rk.dname;
	wl = rrset->rk.dname_len;
	/* skip a leading wildcard label in the dname (RFC4035 2.2) */
	if(dname_is_wild(wn)) {
		wn += 2;
		wl -= 2;
	}
	labdiff = (dname_count_labels(wn) - 1) - (int)labcount;
	if(labdiff > 0) {
		*wc = wn;
		dname_remove_labels(wc, &wl, labdiff);
		*wc_len = wl;
		return 1;
	}
	return 1;
}

int
val_chase_cname(struct query_info* qchase, struct reply_info* rep,
	size_t* cname_skip) {
	size_t i;
	/* skip any DNAMEs, go to the CNAME for next part */
	for(i = *cname_skip; i < rep->an_numrrsets; i++) {
		if(ntohs(rep->rrsets[i]->rk.type) == LDNS_RR_TYPE_CNAME &&
			query_dname_compare(qchase->qname, rep->rrsets[i]->
				rk.dname) == 0) {
			qchase->qname = NULL;
			get_cname_target(rep->rrsets[i], &qchase->qname,
				&qchase->qname_len);
			if(!qchase->qname)
				return 0; /* bad CNAME rdata */
			(*cname_skip) = i+1;
			return 1;
		}
	}
	return 0; /* CNAME classified but no matching CNAME ?! */
}

/** see if rrset has signer name as one of the rrsig signers */
static int
rrset_has_signer(struct ub_packed_rrset_key* rrset, uint8_t* name, size_t len)
{
	struct packed_rrset_data* d = (struct packed_rrset_data*)rrset->
		entry.data;
	size_t i;
	for(i = d->count; i< d->count+d->rrsig_count; i++) {
		if(d->rr_len[i] > 2+18+len) {
			/* at least rdatalen + signature + signame (+1 sig)*/
			if(!dname_valid(d->rr_data[i]+2+18, d->rr_len[i]-2-18))
				continue;
			if(query_dname_compare(name, d->rr_data[i]+2+18) == 0)
			{
				return 1;
			}
		}
	}
	return 0;
}

void 
val_fill_reply(struct reply_info* chase, struct reply_info* orig, 
	size_t skip, uint8_t* name, size_t len, uint8_t* signer)
{
	size_t i;
	int seen_dname = 0;
	chase->rrset_count = 0;
	chase->an_numrrsets = 0;
	chase->ns_numrrsets = 0;
	chase->ar_numrrsets = 0;
	/* ANSWER section */
	for(i=skip; i<orig->an_numrrsets; i++) {
		if(!signer) {
			if(query_dname_compare(name, 
				orig->rrsets[i]->rk.dname) == 0)
				chase->rrsets[chase->an_numrrsets++] = 
					orig->rrsets[i];
		} else if(seen_dname && ntohs(orig->rrsets[i]->rk.type) == 
			LDNS_RR_TYPE_CNAME) {
			chase->rrsets[chase->an_numrrsets++] = orig->rrsets[i];
			seen_dname = 0;
		} else if(rrset_has_signer(orig->rrsets[i], name, len)) {
			chase->rrsets[chase->an_numrrsets++] = orig->rrsets[i];
			if(ntohs(orig->rrsets[i]->rk.type) == 
				LDNS_RR_TYPE_DNAME) {
					seen_dname = 1;
			}
		}
	}	
	/* AUTHORITY section */
	for(i = (skip > orig->an_numrrsets)?skip:orig->an_numrrsets;
		i<orig->an_numrrsets+orig->ns_numrrsets; 
		i++) {
		if(!signer) {
			if(query_dname_compare(name, 
				orig->rrsets[i]->rk.dname) == 0)
				chase->rrsets[chase->an_numrrsets+
				    chase->ns_numrrsets++] = orig->rrsets[i];
		} else if(rrset_has_signer(orig->rrsets[i], name, len)) {
			chase->rrsets[chase->an_numrrsets+
				chase->ns_numrrsets++] = orig->rrsets[i];
		}
	}
	/* ADDITIONAL section */
	for(i= (skip>orig->an_numrrsets+orig->ns_numrrsets)?
		skip:orig->an_numrrsets+orig->ns_numrrsets; 
		i<orig->rrset_count; i++) {
		if(!signer) {
			if(query_dname_compare(name, 
				orig->rrsets[i]->rk.dname) == 0)
			    chase->rrsets[chase->an_numrrsets
				+orig->ns_numrrsets+chase->ar_numrrsets++] 
				= orig->rrsets[i];
		} else if(rrset_has_signer(orig->rrsets[i], name, len)) {
			chase->rrsets[chase->an_numrrsets+orig->ns_numrrsets+
				chase->ar_numrrsets++] = orig->rrsets[i];
		}
	}
	chase->rrset_count = chase->an_numrrsets + chase->ns_numrrsets + 
		chase->ar_numrrsets;
}

void val_reply_remove_auth(struct reply_info* rep, size_t index)
{
	log_assert(index < rep->rrset_count);
	log_assert(index >= rep->an_numrrsets);
	log_assert(index < rep->an_numrrsets+rep->ns_numrrsets);
	memmove(rep->rrsets+index, rep->rrsets+index+1,
		sizeof(struct ub_packed_rrset_key*)*
		(rep->rrset_count - index - 1));
	rep->ns_numrrsets--;
	rep->rrset_count--;
}

void
val_check_nonsecure(struct module_env* env, struct reply_info* rep) 
{
	size_t i;
	/* authority */
	for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->ns_numrrsets; i++) {
		if(((struct packed_rrset_data*)rep->rrsets[i]->entry.data)
			->security != sec_status_secure) {
			/* because we want to return the authentic original
			 * message when presented with CD-flagged queries,
			 * we need to preserve AUTHORITY section data.
			 * However, this rrset is not signed or signed
			 * with the wrong keys. Validation has tried to
			 * verify this rrset with the keysets of import.
			 * But this rrset did not verify.
			 * Therefore the message is bogus.
			 */

			/* check if authority has an NS record
			 * which is bad, and there is an answer section with
			 * data.  In that case, delete NS and additional to 
			 * be lenient and make a minimal response */
			if(rep->an_numrrsets != 0 &&
				ntohs(rep->rrsets[i]->rk.type) 
				== LDNS_RR_TYPE_NS) {
				verbose(VERB_ALGO, "truncate to minimal");
				rep->ar_numrrsets = 0;
				rep->rrset_count = rep->an_numrrsets +
					rep->ns_numrrsets;
				/* remove this unneeded authority rrset */
				memmove(rep->rrsets+i, rep->rrsets+i+1, 
					sizeof(struct ub_packed_rrset_key*)*
					(rep->rrset_count - i - 1));
				rep->ns_numrrsets--;
				rep->rrset_count--;
				i--;
				return;
			}

			log_nametypeclass(VERB_QUERY, "message is bogus, "
				"non secure rrset",
				rep->rrsets[i]->rk.dname, 
				ntohs(rep->rrsets[i]->rk.type),
				ntohs(rep->rrsets[i]->rk.rrset_class));
			rep->security = sec_status_bogus;
			return;
		}
	}
	/* additional */
	if(!env->cfg->val_clean_additional)
		return;
	for(i=rep->an_numrrsets+rep->ns_numrrsets; i<rep->rrset_count; i++) {
		if(((struct packed_rrset_data*)rep->rrsets[i]->entry.data)
			->security != sec_status_secure) {
			/* This does not cause message invalidation. It was
			 * simply unsigned data in the additional. The
			 * RRSIG must have been truncated off the message.
			 *
			 * However, we do not want to return possible bogus
			 * data to clients that rely on this service for
			 * their authentication.
			 */
			/* remove this unneeded additional rrset */
			memmove(rep->rrsets+i, rep->rrsets+i+1, 
				sizeof(struct ub_packed_rrset_key*)*
				(rep->rrset_count - i - 1));
			rep->ar_numrrsets--;
			rep->rrset_count--;
			i--;
		}
	}
}

/** check no anchor and unlock */
static int
check_no_anchor(struct val_anchors* anchors, uint8_t* nm, size_t l, uint16_t c)
{
	struct trust_anchor* ta;
	if((ta=anchors_lookup(anchors, nm, l, c))) {
		lock_basic_unlock(&ta->lock);
	}
	return !ta;
}

void 
val_mark_indeterminate(struct reply_info* rep, struct val_anchors* anchors, 
	struct rrset_cache* r, struct module_env* env)
{
	size_t i;
	struct packed_rrset_data* d;
	for(i=0; i<rep->rrset_count; i++) {
		d = (struct packed_rrset_data*)rep->rrsets[i]->entry.data;
		if(d->security == sec_status_unchecked &&
		   check_no_anchor(anchors, rep->rrsets[i]->rk.dname,
			rep->rrsets[i]->rk.dname_len, 
			ntohs(rep->rrsets[i]->rk.rrset_class))) 
		{ 	
			/* mark as indeterminate */
			d->security = sec_status_indeterminate;
			rrset_update_sec_status(r, rep->rrsets[i], *env->now);
		}
	}
}

void 
val_mark_insecure(struct reply_info* rep, uint8_t* kname,
	struct rrset_cache* r, struct module_env* env)
{
	size_t i;
	struct packed_rrset_data* d;
	for(i=0; i<rep->rrset_count; i++) {
		d = (struct packed_rrset_data*)rep->rrsets[i]->entry.data;
		if(d->security == sec_status_unchecked &&
		   dname_subdomain_c(rep->rrsets[i]->rk.dname, kname)) {
			/* mark as insecure */
			d->security = sec_status_insecure;
			rrset_update_sec_status(r, rep->rrsets[i], *env->now);
		}
	}
}

size_t 
val_next_unchecked(struct reply_info* rep, size_t skip)
{
	size_t i;
	struct packed_rrset_data* d;
	for(i=skip+1; i<rep->rrset_count; i++) {
		d = (struct packed_rrset_data*)rep->rrsets[i]->entry.data;
		if(d->security == sec_status_unchecked) {
			return i;
		}
	}
	return rep->rrset_count;
}

const char*
val_classification_to_string(enum val_classification subtype)
{
	switch(subtype) {
		case VAL_CLASS_UNTYPED: 	return "untyped";
		case VAL_CLASS_UNKNOWN: 	return "unknown";
		case VAL_CLASS_POSITIVE: 	return "positive";
		case VAL_CLASS_CNAME: 		return "cname";
		case VAL_CLASS_NODATA: 		return "nodata";
		case VAL_CLASS_NAMEERROR: 	return "nameerror";
		case VAL_CLASS_CNAMENOANSWER: 	return "cnamenoanswer";
		case VAL_CLASS_REFERRAL: 	return "referral";
		case VAL_CLASS_ANY: 		return "qtype_any";
		default:
			return "bad_val_classification";
	}
}

/** log a sock_list entry */
static void
sock_list_logentry(enum verbosity_value v, const char* s, struct sock_list* p)
{
	if(p->len)
		log_addr(v, s, &p->addr, p->len);
	else	verbose(v, "%s cache", s);
}

void val_blacklist(struct sock_list** blacklist, struct regional* region,
	struct sock_list* origin, int cross)
{
	/* debug printout */
	if(verbosity >= VERB_ALGO) {
		struct sock_list* p;
		for(p=*blacklist; p; p=p->next)
			sock_list_logentry(VERB_ALGO, "blacklist", p);
		if(!origin)
			verbose(VERB_ALGO, "blacklist add: cache");
		for(p=origin; p; p=p->next)
			sock_list_logentry(VERB_ALGO, "blacklist add", p);
	}
	/* blacklist the IPs or the cache */
	if(!origin) {
		/* only add if nothing there. anything else also stops cache*/
		if(!*blacklist)
			sock_list_insert(blacklist, NULL, 0, region);
	} else if(!cross)
		sock_list_prepend(blacklist, origin);
	else	sock_list_merge(blacklist, region, origin);
}

int val_has_signed_nsecs(struct reply_info* rep, char** reason)
{
	size_t i, num_nsec = 0, num_nsec3 = 0;
	struct packed_rrset_data* d;
	for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->ns_numrrsets; i++) {
		if(rep->rrsets[i]->rk.type == htons(LDNS_RR_TYPE_NSEC))
			num_nsec++;
		else if(rep->rrsets[i]->rk.type == htons(LDNS_RR_TYPE_NSEC3))
			num_nsec3++;
		else continue;
		d = (struct packed_rrset_data*)rep->rrsets[i]->entry.data;
		if(d && d->rrsig_count != 0) {
			return 1;
		}
	}
	if(num_nsec == 0 && num_nsec3 == 0)
		*reason = "no DNSSEC records";
	else if(num_nsec != 0)
		*reason = "no signatures over NSECs";
	else	*reason = "no signatures over NSEC3s";
	return 0;
}

struct dns_msg* 
val_find_DS(struct module_env* env, uint8_t* nm, size_t nmlen, uint16_t c, 
	struct regional* region, uint8_t* topname)
{
	struct dns_msg* msg;
	struct query_info qinfo;
	struct ub_packed_rrset_key *rrset = rrset_cache_lookup(
		env->rrset_cache, nm, nmlen, LDNS_RR_TYPE_DS, c, 0, 
		*env->now, 0);
	if(rrset) {
		/* DS rrset exists. Return it to the validator immediately*/
		struct ub_packed_rrset_key* copy = packed_rrset_copy_region(
			rrset, region, *env->now);
		lock_rw_unlock(&rrset->entry.lock);
		if(!copy)
			return NULL;
		msg = dns_msg_create(nm, nmlen, LDNS_RR_TYPE_DS, c, region, 1);
		if(!msg)
			return NULL;
		msg->rep->rrsets[0] = copy;
		msg->rep->rrset_count++;
		msg->rep->an_numrrsets++;
		return msg;
	}
	/* lookup in rrset and negative cache for NSEC/NSEC3 */
	qinfo.qname = nm;
	qinfo.qname_len = nmlen;
	qinfo.qtype = LDNS_RR_TYPE_DS;
	qinfo.qclass = c;
	qinfo.local_alias = NULL;
	/* do not add SOA to reply message, it is going to be used internal */
	msg = val_neg_getmsg(env->neg_cache, &qinfo, region, env->rrset_cache,
		env->scratch_buffer, *env->now, 0, topname, env->cfg);
	return msg;
}
