From f6753a0f1018133df552347a199e0362fc1dac68 Mon Sep 17 00:00:00 2001
From: "W.C.A. Wijngaards" <wouter@nlnetlabs.nl>
Date: Mon, 1 Aug 2022 13:24:40 +0200
Subject: [PATCH] - Fix the novel ghost domain issues CVE-2022-30698 and
 CVE-2022-30699.

---
 cachedb/cachedb.c                 |   2 +-
 daemon/cachedump.c                |   5 +-
 daemon/worker.c                   |   2 +-
 dns64/dns64.c                     |   4 +-
 ipsecmod/ipsecmod.c               |   2 +-
 iterator/iter_utils.c             |   4 +-
 iterator/iter_utils.h             |   3 +-
 iterator/iterator.c               |  19 +--
 pythonmod/interface.i             |   5 +-
 pythonmod/pythonmod_utils.c       |   3 +-
 services/cache/dns.c              | 111 +++++++++++++++---
 services/cache/dns.h              |  18 ++-
 services/mesh.c                   |   1 +
 testdata/iter_prefetch_change.rpl |  16 +--
 util/module.h                     |   6 +
 validator/validator.c             |   4 +-
 16 files changed, 157 insertions(+), 48 deletions(-)

diff --git a/cachedb/cachedb.c b/cachedb/cachedb.c
index af4ffe5..6e3dcfd 100644
--- a/cachedb/cachedb.c
+++ b/cachedb/cachedb.c
@@ -662,7 +662,7 @@ cachedb_intcache_store(struct module_qstate* qstate)
 		return;
 	(void)dns_cache_store(qstate->env, &qstate->qinfo,
 		qstate->return_msg->rep, 0, qstate->prefetch_leeway, 0,
-		qstate->region, store_flags);
+		qstate->region, store_flags, qstate->qstarttime);
 }
 
 /**
diff --git a/daemon/cachedump.c b/daemon/cachedump.c
index b1ce53b..908d2f9 100644
--- a/daemon/cachedump.c
+++ b/daemon/cachedump.c
@@ -677,7 +677,8 @@ load_msg(RES* ssl, sldns_buffer* buf, struct worker* worker)
 	if(!go_on) 
 		return 1; /* skip this one, not all references satisfied */
 
-	if(!dns_cache_store(&worker->env, &qinf, &rep, 0, 0, 0, NULL, flags)) {
+	if(!dns_cache_store(&worker->env, &qinf, &rep, 0, 0, 0, NULL, flags,
+		*worker->env.now)) {
 		log_warn("error out of memory");
 		return 0;
 	}
@@ -848,7 +849,7 @@ int print_deleg_lookup(RES* ssl, struct worker* worker, uint8_t* nm,
 	while(1) {
 		dp = dns_cache_find_delegation(&worker->env, nm, nmlen, 
 			qinfo.qtype, qinfo.qclass, region, &msg, 
-			*worker->env.now);
+			*worker->env.now, 0, NULL, 0);
 		if(!dp) {
 			return ssl_printf(ssl, "no delegation from "
 				"cache; goes to configured roots\n");
diff --git a/daemon/worker.c b/daemon/worker.c
index e9e163a..9c0263f 100644
--- a/daemon/worker.c
+++ b/daemon/worker.c
@@ -460,7 +460,7 @@ answer_norec_from_cache(struct worker* worker, struct query_info* qinfo,
 
 	dp = dns_cache_find_delegation(&worker->env, qinfo->qname, 
 		qinfo->qname_len, qinfo->qtype, qinfo->qclass,
-		worker->scratchpad, &msg, timenow);
+		worker->scratchpad, &msg, timenow, 0, NULL, 0);
 	if(!dp) { /* no delegation, need to reprime */
 		return 0;
 	}
diff --git a/dns64/dns64.c b/dns64/dns64.c
index c79bc9c..0546364 100644
--- a/dns64/dns64.c
+++ b/dns64/dns64.c
@@ -652,7 +652,7 @@ handle_event_moddone(struct module_qstate* qstate, int id)
 	if ( (!iq || !iq->started_no_cache_store) &&
 		qstate->return_msg && qstate->return_msg->rep &&
 		!dns_cache_store(qstate->env, &qstate->qinfo, qstate->return_msg->rep,
-		0, 0, 0, NULL, qstate->query_flags))
+		0, 0, 0, NULL, qstate->query_flags, qstate->qstarttime))
 		log_err("out of memory");
 
 	/* do nothing */
@@ -986,7 +986,7 @@ dns64_inform_super(struct module_qstate* qstate, int id,
 	/* Store the generated response in cache. */
 	if ( (!super_dq || !super_dq->started_no_cache_store) &&
 		!dns_cache_store(super->env, &super->qinfo, super->return_msg->rep,
-		0, 0, 0, NULL, super->query_flags))
+		0, 0, 0, NULL, super->query_flags, qstate->qstarttime))
 		log_err("out of memory");
 }
 
diff --git a/ipsecmod/ipsecmod.c b/ipsecmod/ipsecmod.c
index e42af6f..a35f6e6 100644
--- a/ipsecmod/ipsecmod.c
+++ b/ipsecmod/ipsecmod.c
@@ -456,7 +456,7 @@ ipsecmod_handle_query(struct module_qstate* qstate,
 	/* Store A/AAAA in cache. */
 	if(!dns_cache_store(qstate->env, &qstate->qinfo,
 		qstate->return_msg->rep, 0, qstate->prefetch_leeway,
-		0, qstate->region, qstate->query_flags)) {
+		0, qstate->region, qstate->query_flags, qstate->qstarttime)) {
 		log_err("ipsecmod: out of memory caching record");
 	}
 	qstate->ext_state[id] = module_finished;
diff --git a/iterator/iter_utils.c b/iterator/iter_utils.c
index 668f898..25060ab 100644
--- a/iterator/iter_utils.c
+++ b/iterator/iter_utils.c
@@ -656,10 +656,10 @@ dns_copy_msg(struct dns_msg* from, struct regional* region)
 void 
 iter_dns_store(struct module_env* env, struct query_info* msgqinf,
 	struct reply_info* msgrep, int is_referral, time_t leeway, int pside,
-	struct regional* region, uint16_t flags)
+	struct regional* region, uint16_t flags, time_t qstarttime)
 {
 	if(!dns_cache_store(env, msgqinf, msgrep, is_referral, leeway,
-		pside, region, flags))
+		pside, region, flags, qstarttime))
 		log_err("out of memory: cannot store data in cache");
 }
 
diff --git a/iterator/iter_utils.h b/iterator/iter_utils.h
index 509d292..6253b5f 100644
--- a/iterator/iter_utils.h
+++ b/iterator/iter_utils.h
@@ -132,6 +132,7 @@ struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional);
  * 	can be prefetch-updates.
  * @param region: to copy modified (cache is better) rrs back to.
  * @param flags: with BIT_CD for dns64 AAAA translated queries.
+ * @param qstarttime: time of query start.
  * return void, because we are not interested in alloc errors,
  * 	the iterator and validator can operate on the results in their
  * 	scratch space (the qstate.region) and are not dependent on the cache.
@@ -140,7 +141,7 @@ struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional);
  */
 void iter_dns_store(struct module_env* env, struct query_info* qinf,
 	struct reply_info* rep, int is_referral, time_t leeway, int pside,
-	struct regional* region, uint16_t flags);
+	struct regional* region, uint16_t flags, time_t qstarttime);
 
 /**
  * Select randomly with n/m probability.
diff --git a/iterator/iterator.c b/iterator/iterator.c
index f0105ad..40afbc8 100644
--- a/iterator/iterator.c
+++ b/iterator/iterator.c
@@ -370,7 +370,7 @@ error_response_cache(struct module_qstate* qstate, int id, int rcode)
 		err.security = sec_status_indeterminate;
 		verbose(VERB_ALGO, "store error response in message cache");
 		iter_dns_store(qstate->env, &qstate->qinfo, &err, 0, 0, 0, NULL,
-			qstate->query_flags);
+			qstate->query_flags, qstate->qstarttime);
 	}
 	return error_response(qstate, id, rcode);
 }
@@ -1477,7 +1477,8 @@ processInitRequest(struct module_qstate* qstate, struct iter_qstate* iq,
 		     iq->dp = dns_cache_find_delegation(qstate->env, delname, 
 			delnamelen, iq->qchase.qtype, iq->qchase.qclass, 
 			qstate->region, &iq->deleg_msg,
-			*qstate->env->now+qstate->prefetch_leeway);
+			*qstate->env->now+qstate->prefetch_leeway, 1,
+			dpname, dpnamelen);
 		else iq->dp = NULL;
 
 		/* If the cache has returned nothing, then we have a 
@@ -1799,7 +1800,8 @@ generate_parentside_target_query(struct module_qstate* qstate,
 			subiq->dp = dns_cache_find_delegation(qstate->env, 
 				name, namelen, qtype, qclass, subq->region,
 				&subiq->deleg_msg,
-				*qstate->env->now+subq->prefetch_leeway); 
+				*qstate->env->now+subq->prefetch_leeway,
+				1, NULL, 0);	
 			/* if no dp, then it's from root, refetch unneeded */
 			if(subiq->dp) { 
 				subiq->dnssec_expected = iter_indicates_dnssec(
@@ -2847,7 +2849,8 @@ processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
 			iter_dns_store(qstate->env, &iq->response->qinfo,
 				iq->response->rep, 0, qstate->prefetch_leeway,
 				iq->dp&&iq->dp->has_parent_side_NS,
-				qstate->region, qstate->query_flags);
+				qstate->region, qstate->query_flags,
+				qstate->qstarttime);
 		/* close down outstanding requests to be discarded */
 		outbound_list_clear(&iq->outlist);
 		iq->num_current_queries = 0;
@@ -2944,7 +2947,8 @@ processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
 			/* Store the referral under the current query */
 			/* no prefetch-leeway, since its not the answer */
 			iter_dns_store(qstate->env, &iq->response->qinfo,
-				iq->response->rep, 1, 0, 0, NULL, 0);
+				iq->response->rep, 1, 0, 0, NULL, 0,
+				qstate->qstarttime);
 			if(iq->store_parent_NS)
 				iter_store_parentside_NS(qstate->env, 
 					iq->response->rep);
@@ -3057,7 +3061,7 @@ processQueryResponse(struct module_qstate* qstate, struct iter_qstate* iq,
 			iter_dns_store(qstate->env, &iq->response->qinfo,
 				iq->response->rep, 1, qstate->prefetch_leeway,
 				iq->dp&&iq->dp->has_parent_side_NS, NULL,
-				qstate->query_flags);
+				qstate->query_flags, qstate->qstarttime);
 		/* set the current request's qname to the new value. */
 		iq->qchase.qname = sname;
 		iq->qchase.qname_len = snamelen;
@@ -3626,7 +3630,8 @@ processFinished(struct module_qstate* qstate, struct iter_qstate* iq,
 			iter_dns_store(qstate->env, &qstate->qinfo, 
 				iq->response->rep, 0, qstate->prefetch_leeway,
 				iq->dp&&iq->dp->has_parent_side_NS,
-				qstate->region, qstate->query_flags);
+				qstate->region, qstate->query_flags,
+				qstate->qstarttime);
 		}
 	}
 	qstate->return_rcode = LDNS_RCODE_NOERROR;
diff --git a/pythonmod/interface.i b/pythonmod/interface.i
index ce7dcde..bdd6906 100644
--- a/pythonmod/interface.i
+++ b/pythonmod/interface.i
@@ -1371,7 +1371,8 @@ int set_return_msg(struct module_qstate* qstate,
 /* Functions which we will need to lookup delegations */
 struct delegpt* dns_cache_find_delegation(struct module_env* env,
         uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass,
-        struct regional* region, struct dns_msg** msg, uint32_t timenow);
+        struct regional* region, struct dns_msg** msg, uint32_t timenow,
+        int noexpiredabove, uint8_t* expiretop, size_t expiretoplen);
 int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags,
         struct delegpt* dp);
 struct iter_hints_stub* hints_lookup_stub(struct iter_hints* hints,
@@ -1400,7 +1401,7 @@ struct delegpt* find_delegation(struct module_qstate* qstate, char *nm, size_t n
     qinfo.qclass = LDNS_RR_CLASS_IN;
 
     while(1) {
-        dp = dns_cache_find_delegation(qstate->env, (uint8_t*)nm, nmlen, qinfo.qtype, qinfo.qclass, region, &msg, timenow);
+        dp = dns_cache_find_delegation(qstate->env, (uint8_t*)nm, nmlen, qinfo.qtype, qinfo.qclass, region, &msg, timenow, 0, NULL, 0);
         if(!dp)
             return NULL;
         if(iter_dp_is_useless(&qinfo, BIT_RD, dp)) {
diff --git a/pythonmod/pythonmod_utils.c b/pythonmod/pythonmod_utils.c
index 21a16bb..05ce136 100644
--- a/pythonmod/pythonmod_utils.c
+++ b/pythonmod/pythonmod_utils.c
@@ -72,7 +72,8 @@ int storeQueryInCache(struct module_qstate* qstate, struct query_info* qinfo,
 	}
 
 	return dns_cache_store(qstate->env, qinfo, msgrep, is_referral,
-		qstate->prefetch_leeway, 0, NULL, qstate->query_flags);
+		qstate->prefetch_leeway, 0, NULL, qstate->query_flags,
+		qstate->qstarttime);
 }
 
 /* Invalidate the message associated with query_info stored in message cache */
diff --git a/services/cache/dns.c b/services/cache/dns.c
index 5b64fe4..c29b909 100644
--- a/services/cache/dns.c
+++ b/services/cache/dns.c
@@ -68,11 +68,16 @@
  * 	in a prefetch situation to be updated (without becoming sticky).
  * @param qrep: update rrsets here if cache is better
  * @param region: for qrep allocs.
+ * @param qstarttime: time when delegations were looked up, this is perhaps
+ *      earlier than the time in now. The time is used to determine if RRsets
+ *      of type NS have expired, so that they can only be updated using
+ *      lookups of delegation points that did not use them, since they had
+ *      expired then.
  */
 static void
 store_rrsets(struct module_env* env, struct reply_info* rep, time_t now,
 	time_t leeway, int pside, struct reply_info* qrep,
-	struct regional* region)
+	struct regional* region, time_t qstarttime)
 {
 	size_t i;
 	/* see if rrset already exists in cache, if not insert it. */
@@ -81,8 +86,8 @@ store_rrsets(struct module_env* env, struct reply_info* rep, time_t now,
 		rep->ref[i].id = rep->rrsets[i]->id;
 		/* update ref if it was in the cache */
 		switch(rrset_cache_update(env->rrset_cache, &rep->ref[i],
-				env->alloc, now + ((ntohs(rep->ref[i].key->rk.type)==
-				LDNS_RR_TYPE_NS && !pside)?0:leeway))) {
+				env->alloc, ((ntohs(rep->ref[i].key->rk.type)==
+				LDNS_RR_TYPE_NS && !pside)?qstarttime:now + leeway))) {
 		case 0: /* ref unchanged, item inserted */
 			break;
 		case 2: /* ref updated, cache is superior */
@@ -155,7 +160,8 @@ msg_del_servfail(struct module_env* env, struct query_info* qinfo,
 void 
 dns_cache_store_msg(struct module_env* env, struct query_info* qinfo,
 	hashvalue_type hash, struct reply_info* rep, time_t leeway, int pside,
-	struct reply_info* qrep, uint32_t flags, struct regional* region)
+	struct reply_info* qrep, uint32_t flags, struct regional* region,
+	time_t qstarttime)
 {
 	struct msgreply_entry* e;
 	time_t ttl = rep->ttl;
@@ -170,7 +176,8 @@ dns_cache_store_msg(struct module_env* env, struct query_info* qinfo,
 	/* there was a reply_info_sortref(rep) here but it seems to be
 	 * unnecessary, because the cache gets locked per rrset. */
 	reply_info_set_ttls(rep, *env->now);
-	store_rrsets(env, rep, *env->now, leeway, pside, qrep, region);
+	store_rrsets(env, rep, *env->now, leeway, pside, qrep, region,
+		qstarttime);
 	if(ttl == 0 && !(flags & DNSCACHE_STORE_ZEROTTL)) {
 		/* we do not store the message, but we did store the RRs,
 		 * which could be useful for delegation information */
@@ -194,10 +201,51 @@ dns_cache_store_msg(struct module_env* env, struct query_info* qinfo,
 	slabhash_insert(env->msg_cache, hash, &e->entry, rep, env->alloc);
 }
 
+/** see if an rrset is expired above the qname, return upper qname. */
+static int
+rrset_expired_above(struct module_env* env, uint8_t** qname, size_t* qnamelen,
+	uint16_t searchtype, uint16_t qclass, time_t now, uint8_t* expiretop,
+	size_t expiretoplen)
+{
+	struct ub_packed_rrset_key *rrset;
+	uint8_t lablen;
+
+	while(*qnamelen > 0) {
+		/* look one label higher */
+		lablen = **qname;
+		*qname += lablen + 1;
+		*qnamelen -= lablen + 1;
+		if(*qnamelen <= 0)
+			break;
+
+		/* looks up with a time of 0, to see expired entries */
+		if((rrset = rrset_cache_lookup(env->rrset_cache, *qname,
+			*qnamelen, searchtype, qclass, 0, 0, 0))) {
+			struct packed_rrset_data* data =
+				(struct packed_rrset_data*)rrset->entry.data;
+			if(now > data->ttl) {
+				/* it is expired, this is not wanted */
+				lock_rw_unlock(&rrset->entry.lock);
+				log_nametypeclass(VERB_ALGO, "this rrset is expired", *qname, searchtype, qclass);
+				return 1;
+			}
+			/* it is not expired, continue looking */
+			lock_rw_unlock(&rrset->entry.lock);
+		}
+
+		/* do not look above the expiretop. */
+		if(expiretop && *qnamelen == expiretoplen &&
+			query_dname_compare(*qname, expiretop)==0)
+			break;
+	}
+	return 0;
+}
+
 /** find closest NS or DNAME and returns the rrset (locked) */
 static struct ub_packed_rrset_key*
 find_closest_of_type(struct module_env* env, uint8_t* qname, size_t qnamelen, 
-	uint16_t qclass, time_t now, uint16_t searchtype, int stripfront)
+	uint16_t qclass, time_t now, uint16_t searchtype, int stripfront,
+	int noexpiredabove, uint8_t* expiretop, size_t expiretoplen)
 {
 	struct ub_packed_rrset_key *rrset;
 	uint8_t lablen;
@@ -212,8 +260,40 @@ find_closest_of_type(struct module_env* env, uint8_t* qname, size_t qnamelen,
 	/* snip off front part of qname until the type is found */
 	while(qnamelen > 0) {
 		if((rrset = rrset_cache_lookup(env->rrset_cache, qname, 
-			qnamelen, searchtype, qclass, 0, now, 0)))
-			return rrset;
+			qnamelen, searchtype, qclass, 0, now, 0))) {
+			uint8_t* origqname = qname;
+			size_t origqnamelen = qnamelen;
+			if(!noexpiredabove)
+				return rrset;
+			/* if expiretop set, do not look above it, but
+			 * qname is equal, so the just found result is also
+			 * the nonexpired above part. */
+			if(expiretop && qnamelen == expiretoplen &&
+				query_dname_compare(qname, expiretop)==0)
+				return rrset;
+			/* check for expiry, but we have to let go of the rrset
+			 * for the lock ordering */
+			lock_rw_unlock(&rrset->entry.lock);
+			/* the expired_above function always takes off one
+			 * label (if qnamelen>0) and returns the final qname
+			 * where it searched, so we can continue from there
+			 * turning the O N*N search into O N. */
+			if(!rrset_expired_above(env, &qname, &qnamelen,
+				searchtype, qclass, now, expiretop,
+				expiretoplen)) {
+				/* we want to return rrset, but it may be
+				 * gone from cache, if so, just loop like
+				 * it was not in the cache in the first place.
+				 */
+				if((rrset = rrset_cache_lookup(env->
+					rrset_cache, origqname, origqnamelen,
+					searchtype, qclass, 0, now, 0))) {
+					return rrset;
+				}
+			}
+			log_nametypeclass(VERB_ALGO, "ignoring rrset because expired rrsets exist above it", origqname, searchtype, qclass);
+			continue;
+		}
 
 		/* snip off front label */
 		lablen = *qname;
@@ -461,7 +541,8 @@ dns_msg_ansadd(struct dns_msg* msg, struct regional* region,
 struct delegpt* 
 dns_cache_find_delegation(struct module_env* env, uint8_t* qname, 
 	size_t qnamelen, uint16_t qtype, uint16_t qclass, 
-	struct regional* region, struct dns_msg** msg, time_t now)
+	struct regional* region, struct dns_msg** msg, time_t now,
+	int noexpiredabove, uint8_t* expiretop, size_t expiretoplen)
 {
 	/* try to find closest NS rrset */
 	struct ub_packed_rrset_key* nskey;
@@ -469,7 +550,7 @@ dns_cache_find_delegation(struct module_env* env, uint8_t* qname,
 	struct delegpt* dp;
 
 	nskey = find_closest_of_type(env, qname, qnamelen, qclass, now,
-		LDNS_RR_TYPE_NS, 0);
+		LDNS_RR_TYPE_NS, 0, noexpiredabove, expiretop, expiretoplen);
 	if(!nskey) /* hope the caller has hints to prime or something */
 		return NULL;
 	nsdata = (struct packed_rrset_data*)nskey->entry.data;
@@ -835,7 +916,7 @@ dns_cache_lookup(struct module_env* env,
 	 * consistent with the DNAME */
 	if(!no_partial &&
 		(rrset=find_closest_of_type(env, qname, qnamelen, qclass, now,
-		LDNS_RR_TYPE_DNAME, 1))) {
+		LDNS_RR_TYPE_DNAME, 1, 0, NULL, 0))) {
 		/* synthesize a DNAME+CNAME message based on this */
 		enum sec_status sec_status = sec_status_unchecked;
 		struct dns_msg* msg = synth_dname_msg(rrset, region, now, &k,
@@ -968,7 +1049,7 @@ dns_cache_lookup(struct module_env* env,
 int
 dns_cache_store(struct module_env* env, struct query_info* msgqinf,
         struct reply_info* msgrep, int is_referral, time_t leeway, int pside,
-	struct regional* region, uint32_t flags)
+	struct regional* region, uint32_t flags, time_t qstarttime)
 {
 	struct reply_info* rep = NULL;
 	/* alloc, malloc properly (not in region, like msg is) */
@@ -991,9 +1072,9 @@ dns_cache_store(struct module_env* env, struct query_info* msgqinf,
 			/*ignore ret: it was in the cache, ref updated */
 			/* no leeway for typeNS */
 			(void)rrset_cache_update(env->rrset_cache, &ref, 
-				env->alloc, *env->now + 
+				env->alloc,
 				((ntohs(ref.key->rk.type)==LDNS_RR_TYPE_NS
-				 && !pside) ? 0:leeway));
+				 && !pside) ? qstarttime:*env->now + leeway));
 		}
 		free(rep);
 		return 1;
@@ -1015,7 +1096,7 @@ dns_cache_store(struct module_env* env, struct query_info* msgqinf,
 		rep->flags &= ~(BIT_AA | BIT_CD);
 		h = query_info_hash(&qinf, (uint16_t)flags);
 		dns_cache_store_msg(env, &qinf, h, rep, leeway, pside, msgrep,
-			flags, region);
+			flags, region, qstarttime);
 		/* qname is used inside query_info_entrysetup, and set to 
 		 * NULL. If it has not been used, free it. free(0) is safe. */
 		free(qinf.qname);
diff --git a/services/cache/dns.h b/services/cache/dns.h
index bece837..6ae4514 100644
--- a/services/cache/dns.h
+++ b/services/cache/dns.h
@@ -88,11 +88,13 @@ struct dns_msg {
  * @param flags: flags with BIT_CD for AAAA queries in dns64 translation.
  *   The higher 16 bits are used internally to customize the cache policy.
  *   (See DNSCACHE_STORE_xxx flags).
+ * @param qstarttime: time when the query was started, and thus when the
+ *      delegations were looked up.
  * @return 0 on alloc error (out of memory).
  */
 int dns_cache_store(struct module_env* env, struct query_info* qinf,
         struct reply_info* rep, int is_referral, time_t leeway, int pside,
-	struct regional* region, uint32_t flags);
+	struct regional* region, uint32_t flags, time_t qstarttime);
 
 /**
  * Store message in the cache. Stores in message cache and rrset cache.
@@ -112,11 +114,14 @@ int dns_cache_store(struct module_env* env, struct query_info* qinf,
  * 	can be updated to full TTL even in prefetch situations.
  * @param qrep: message that can be altered with better rrs from cache.
  * @param flags: customization flags for the cache policy.
+ * @param qstarttime: time when the query was started, and thus when the
+ *      delegations were looked up.
  * @param region: to allocate into for qmsg.
  */
 void dns_cache_store_msg(struct module_env* env, struct query_info* qinfo,
 	hashvalue_type hash, struct reply_info* rep, time_t leeway, int pside,
-	struct reply_info* qrep, uint32_t flags, struct regional* region);
+	struct reply_info* qrep, uint32_t flags, struct regional* region,
+	time_t qstarttime);
 
 /**
  * Find a delegation from the cache.
@@ -129,11 +134,18 @@ void dns_cache_store_msg(struct module_env* env, struct query_info* qinfo,
  * @param msg: if not NULL, delegation message is returned here, synthesized
  *	from the cache.
  * @param timenow: the time now, for checking if TTL on cache entries is OK.
+ * @param noexpiredabove: if set, no expired NS rrsets above the one found
+ *      are tolerated. It only returns delegations where the delegations above
+ *      it are valid.
+ * @param expiretop: if not NULL, name where check for expiry ends for
+ *      noexpiredabove.
+ * @param expiretoplen: length of expiretop dname.
  * @return new delegation or NULL on error or if not found in cache.
  */
 struct delegpt* dns_cache_find_delegation(struct module_env* env, 
 	uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass, 
-	struct regional* region, struct dns_msg** msg, time_t timenow);
+	struct regional* region, struct dns_msg** msg, time_t timenow,
+	int noexpiredabove, uint8_t* expiretop, size_t expiretoplen);
 
 /**
  * generate dns_msg from cached message
diff --git a/services/mesh.c b/services/mesh.c
index 5679a8b..b9aac54 100644
--- a/services/mesh.c
+++ b/services/mesh.c
@@ -839,6 +839,7 @@ mesh_state_create(struct module_env* env, struct query_info* qinfo,
 	mstate->s.no_cache_store = 0;
 	mstate->s.need_refetch = 0;
 	mstate->s.was_ratelimited = 0;
+	mstate->s.qstarttime = *env->now;
 
 	/* init modules */
 	for(i=0; i<env->mesh->mods.num; i++) {
diff --git a/testdata/iter_prefetch_change.rpl b/testdata/iter_prefetch_change.rpl
index 007025a..1be9e6a 100644
--- a/testdata/iter_prefetch_change.rpl
+++ b/testdata/iter_prefetch_change.rpl
@@ -22,9 +22,9 @@ REPLY QR NOERROR
 SECTION QUESTION
 . IN NS
 SECTION ANSWER
-. IN NS	K.ROOT-SERVERS.NET.
+. 86400 IN NS	K.ROOT-SERVERS.NET.
 SECTION ADDITIONAL
-K.ROOT-SERVERS.NET.	IN	A	193.0.14.129
+K.ROOT-SERVERS.NET.	86400 IN	A	193.0.14.129
 ENTRY_END
 
 ENTRY_BEGIN
@@ -34,9 +34,9 @@ REPLY QR NOERROR
 SECTION QUESTION
 com. IN A
 SECTION AUTHORITY
-com.	IN NS	a.gtld-servers.net.
+com.	86400 IN NS	a.gtld-servers.net.
 SECTION ADDITIONAL
-a.gtld-servers.net.	IN 	A	192.5.6.30
+a.gtld-servers.net.	86400 IN 	A	192.5.6.30
 ENTRY_END
 RANGE_END
 
@@ -50,9 +50,9 @@ REPLY QR NOERROR
 SECTION QUESTION
 com. IN NS
 SECTION ANSWER
-com.	IN NS	a.gtld-servers.net.
+com.	86400 IN NS	a.gtld-servers.net.
 SECTION ADDITIONAL
-a.gtld-servers.net.	IN 	A	192.5.6.30
+a.gtld-servers.net.	86400 IN 	A	192.5.6.30
 ENTRY_END
 
 ENTRY_BEGIN
@@ -78,9 +78,9 @@ REPLY QR NOERROR
 SECTION QUESTION
 com. IN NS
 SECTION ANSWER
-com.	IN NS	a.gtld-servers.net.
+com.	86400 IN NS	a.gtld-servers.net.
 SECTION ADDITIONAL
-a.gtld-servers.net.	IN 	A	192.5.6.30
+a.gtld-servers.net.	86400 IN 	A	192.5.6.30
 ENTRY_END
 
 ENTRY_BEGIN
diff --git a/util/module.h b/util/module.h
index 81a31a9..09854a1 100644
--- a/util/module.h
+++ b/util/module.h
@@ -652,6 +652,12 @@ struct module_qstate {
 	int need_refetch;
 	/** whether the query (or a subquery) was ratelimited */
 	int was_ratelimited;
+	/** time when query was started. This is when the qstate is created.
+	 * This is used so that type NS data cannot be overwritten by them
+	 * expiring while the lookup is in progress, using data fetched from
+	 * those servers. By comparing expiry time with qstarttime for type NS.
+	 */
+	time_t qstarttime;
 
 	/**
 	 * Attributes of clients that share the qstate that may affect IP-based
diff --git a/validator/validator.c b/validator/validator.c
index d4d48d9..4b731f5 100644
--- a/validator/validator.c
+++ b/validator/validator.c
@@ -2145,7 +2145,7 @@ processFinished(struct module_qstate* qstate, struct val_qstate* vq,
 		if(!qstate->no_cache_store) {
 			if(!dns_cache_store(qstate->env, &vq->orig_msg->qinfo,
 				vq->orig_msg->rep, 0, qstate->prefetch_leeway, 0, NULL,
-				qstate->query_flags)) {
+				qstate->query_flags, qstate->qstarttime)) {
 				log_err("out of memory caching validator results");
 			}
 		}
@@ -2154,7 +2154,7 @@ processFinished(struct module_qstate* qstate, struct val_qstate* vq,
 		/* and this does not get prefetched, so no leeway */
 		if(!dns_cache_store(qstate->env, &vq->orig_msg->qinfo,
 			vq->orig_msg->rep, 1, 0, 0, NULL,
-			qstate->query_flags)) {
+			qstate->query_flags, qstate->qstarttime)) {
 			log_err("out of memory caching validator results");
 		}
 	}
-- 
2.33.0

