network_cmds-596.100.2.tar.gz

[apple/network_cmds.git] / unbound / validator / val_utils.c

/*
 * 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"

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 || subtype == VAL_CLASS_ANY) {
                /* 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_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)
{
        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);
        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)
{
        /* 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);
        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)
{
        enum sec_status sec = sec_status_bogus;
        size_t i, num, numchecked = 0, numhashok = 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++;
                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);
                if(sec == sec_status_secure) {
                        return sec;
                }
                /* If it didn't validate with the DNSKEY, try the next one! */
        }
        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)
{
        /* 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;
        }

        digest_algo = val_favorite_ds_algo(ds_rrset);
        if(sigalg)
                algo_needs_init_ds(&needs, ds_rrset, digest_algo, sigalg);
        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) ||
                        ds_get_digest_algo(ds_rrset, i) != digest_algo) {
                        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;

                sec = verify_dnskeys_with_ds_rr(env, ve, dnskey_rrset, 
                        ds_rrset, i, reason);
                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.");
                                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)
{
        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);

        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)
{
        /* 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;

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

                sec = verify_dnskeys_with_ds_rr(env, ve, dnskey_rrset, 
                        ta_ds, i, reason);
                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.");
                                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;

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

                sec = dnskey_verify_rrset(env, ve, dnskey_rrset,
                        ta_dnskey, i, reason);
                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.");
                                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)
{
        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);

        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;
        }
        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)
{
        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);
                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_check_nonsecure(struct val_env* ve, 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 consists of only 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 && rep->ns_numrrsets == 1 &&
                                ntohs(rep->rrsets[i]->rk.type) 
                                == LDNS_RR_TYPE_NS) {
                                verbose(VERB_ALGO, "truncate to minimal");
                                rep->ns_numrrsets = 0;
                                rep->ar_numrrsets = 0;
                                rep->rrset_count = rep->an_numrrsets;
                                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(!ve->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;
        /* 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);
        return msg;
}