1.2.1 feature: stop AAAA queries that are not needed.

git-svn-id: file:///svn/unbound/trunk@1431 be551aaa-1e26-0410-a405-d3ace91eadb9

doc/Changelog

@@ -3,6 +3,8 @@
 	- find NS rrset more cleanly for qtype NS.
 	- Moved changes to 1.2.0 for release. Thanks to Mark Zealey for
 	  reporting and logs.
+	- 1.2.1 feature: stops resolving AAAAs promiscuously when they
+	  are in the negative cache.
 
 12 January 2009: Wouter
 	- fixed bug in infrastructure lameness cache, did not lowercase

iterator/iter_delegpt.c

@@ -423,3 +423,23 @@ delegpt_add_rrset(struct delegpt* dp, struct regional* region,
 	log_warn("Unknown rrset type added to delegpt");
 	return 1;
 }
+
+void delegpt_add_neg_msg(struct delegpt* dp, struct msgreply_entry* msg)
+{
+	struct reply_info* rep = (struct reply_info*)msg->entry.data;
+	if(!rep) return;
+
+	/* if error or no answers */
+	if(FLAGS_GET_RCODE(rep->flags) != 0 || rep->an_numrrsets == 0) {
+		struct delegpt_ns* ns = delegpt_find_ns(dp, msg->key.qname, 
+			msg->key.qname_len);
+		if(ns) {
+			if(msg->key.qtype == LDNS_RR_TYPE_A)
+				ns->got4 = 1;
+			else if(msg->key.qtype == LDNS_RR_TYPE_AAAA)
+				ns->got6 = 1;
+			if(ns->got4 && ns->got6)
+				ns->resolved = 1;
+		}
+	}
+}

iterator/iter_delegpt.h

@@ -48,6 +48,7 @@ struct delegpt_ns;
 struct delegpt_addr;
 struct dns_msg;
 struct ub_packed_rrset_key;
+struct msgreply_entry;
 
 /**
  * Delegation Point.
@@ -299,4 +300,11 @@ size_t delegpt_count_missing_targets(struct delegpt* dp);
 struct delegpt* delegpt_from_message(struct dns_msg* msg, 
 	struct regional* regional);
 
+/**
+ * Add negative message to delegation point.
+ * @param dp: delegation point.
+ * @param msg: the message added, marks off A or AAAA from an NS entry.
+ */
+void delegpt_add_neg_msg(struct delegpt* dp, struct msgreply_entry* msg);
+
 #endif /* ITERATOR_ITER_DELEGPT_H */

services/cache/dns.c

@@ -142,6 +142,30 @@ addr_to_additional(struct ub_packed_rrset_key* rrset, struct regional* region,
 	}
 }
 
+/** lookup message in message cache */
+static struct msgreply_entry* 
+msg_cache_lookup(struct module_env* env, uint8_t* qname, size_t qnamelen, 
+	uint16_t qtype, uint16_t qclass, uint32_t now, int wr)
+{
+	struct lruhash_entry* e;
+	struct query_info k;
+	hashvalue_t h;
+
+	k.qname = qname;
+	k.qname_len = qnamelen;
+	k.qtype = qtype;
+	k.qclass = qclass;
+	h = query_info_hash(&k);
+	e = slabhash_lookup(env->msg_cache, h, &k, wr);
+
+	if(!e) return NULL;
+	if( now > ((struct reply_info*)e->data)->ttl ) {
+		lock_rw_unlock(&e->lock);
+		return NULL;
+	}
+	return (struct msgreply_entry*)e->key;
+}
+
 /** find and add A and AAAA records for nameservers in delegpt */
 static int
 find_add_addrs(struct module_env* env, uint16_t qclass, 
@@ -149,6 +173,7 @@ find_add_addrs(struct module_env* env, uint16_t qclass,
 	struct dns_msg** msg)
 {
 	struct delegpt_ns* ns;
+	struct msgreply_entry* neg;
 	struct ub_packed_rrset_key* akey;
 	for(ns = dp->nslist; ns; ns = ns->next) {
 		akey = rrset_cache_lookup(env->rrset_cache, ns->name, 
@@ -161,6 +186,13 @@ find_add_addrs(struct module_env* env, uint16_t qclass,
 			if(msg)
 				addr_to_additional(akey, region, *msg, now);
 			lock_rw_unlock(&akey->entry.lock);
+		} else {
+			neg = msg_cache_lookup(env, ns->name, ns->namelen,
+				LDNS_RR_TYPE_A, qclass, now, 0);
+			if(neg) {
+				delegpt_add_neg_msg(dp, neg);
+				lock_rw_unlock(&neg->entry.lock);
+			}
 		}
 		akey = rrset_cache_lookup(env->rrset_cache, ns->name, 
 			ns->namelen, LDNS_RR_TYPE_AAAA, qclass, 0, now, 0);
@@ -172,6 +204,13 @@ find_add_addrs(struct module_env* env, uint16_t qclass,
 			if(msg)
 				addr_to_additional(akey, region, *msg, now);
 			lock_rw_unlock(&akey->entry.lock);
+		} else {
+			neg = msg_cache_lookup(env, ns->name, ns->namelen,
+				LDNS_RR_TYPE_AAAA, qclass, now, 0);
+			if(neg) {
+				delegpt_add_neg_msg(dp, neg);
+				lock_rw_unlock(&neg->entry.lock);
+			}
 		}
 	}
 	return 1;
@@ -183,6 +222,7 @@ cache_fill_missing(struct module_env* env, uint16_t qclass,
 	struct regional* region, struct delegpt* dp)
 {
 	struct delegpt_ns* ns;
+	struct msgreply_entry* neg;
 	struct ub_packed_rrset_key* akey;
 	uint32_t now = *env->now;
 	for(ns = dp->nslist; ns; ns = ns->next) {
@@ -198,6 +238,13 @@ cache_fill_missing(struct module_env* env, uint16_t qclass,
 			log_nametypeclass(VERB_ALGO, "found in cache",
 				ns->name, LDNS_RR_TYPE_A, qclass);
 			lock_rw_unlock(&akey->entry.lock);
+		} else {
+			neg = msg_cache_lookup(env, ns->name, ns->namelen,
+				LDNS_RR_TYPE_A, qclass, now, 0);
+			if(neg) {
+				delegpt_add_neg_msg(dp, neg);
+				lock_rw_unlock(&neg->entry.lock);
+			}
 		}
 		akey = rrset_cache_lookup(env->rrset_cache, ns->name, 
 			ns->namelen, LDNS_RR_TYPE_AAAA, qclass, 0, now, 0);
@@ -209,6 +256,13 @@ cache_fill_missing(struct module_env* env, uint16_t qclass,
 			log_nametypeclass(VERB_ALGO, "found in cache",
 				ns->name, LDNS_RR_TYPE_AAAA, qclass);
 			lock_rw_unlock(&akey->entry.lock);
+		} else {
+			neg = msg_cache_lookup(env, ns->name, ns->namelen,
+				LDNS_RR_TYPE_AAAA, qclass, now, 0);
+			if(neg) {
+				delegpt_add_neg_msg(dp, neg);
+				lock_rw_unlock(&neg->entry.lock);
+			}
 		}
 	}
 	return 1;