Index: contrib/unbound/iterator/iterator.c
===================================================================
--- contrib/unbound/iterator/iterator.c.orig
+++ contrib/unbound/iterator/iterator.c
@@ -117,6 +117,7 @@
 	iq->query_restart_count = 0;
 	iq->referral_count = 0;
 	iq->sent_count = 0;
+	iq->target_count = NULL;
 	iq->wait_priming_stub = 0;
 	iq->refetch_glue = 0;
 	iq->dnssec_expected = 0;
@@ -442,6 +443,26 @@
 	return 1;
 }
 
+/** create target count structure for this query */
+static void
+target_count_create(struct iter_qstate* iq)
+{
+	if(!iq->target_count) {
+		iq->target_count = (int*)calloc(2, sizeof(int));
+		/* if calloc fails we simply do not track this number */
+		if(iq->target_count)
+			iq->target_count[0] = 1;
+	}
+}
+
+static void
+target_count_increase(struct iter_qstate* iq, int num)
+{
+	target_count_create(iq);
+	if(iq->target_count)
+		iq->target_count[1] += num;
+}
+
 /**
  * Generate a subrequest.
  * Generate a local request event. Local events are tied to this module, and
@@ -513,6 +534,10 @@
 		subiq = (struct iter_qstate*)subq->minfo[id];
 		memset(subiq, 0, sizeof(*subiq));
 		subiq->num_target_queries = 0;
+		target_count_create(iq);
+		subiq->target_count = iq->target_count;
+		if(iq->target_count)
+			iq->target_count[0] ++; /* extra reference */
 		subiq->num_current_queries = 0;
 		subiq->depth = iq->depth+1;
 		outbound_list_init(&subiq->outlist);
@@ -1339,6 +1364,12 @@
 
 	if(iq->depth == ie->max_dependency_depth)
 		return 0;
+	if(iq->depth > 0 && iq->target_count &&
+		iq->target_count[1] > MAX_TARGET_COUNT) {
+		verbose(VERB_QUERY, "request has exceeded the maximum "
+			"number of glue fetches %d", iq->target_count[1]);
+		return 0;
+	}
 
 	iter_mark_cycle_targets(qstate, iq->dp);
 	missing = (int)delegpt_count_missing_targets(iq->dp);
@@ -1487,6 +1518,7 @@
 			return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
 		}
 		iq->num_target_queries += qs;
+		target_count_increase(iq, qs);
 		if(qs != 0) {
 			qstate->ext_state[id] = module_wait_subquery;
 			return 0; /* and wait for them */
@@ -1496,6 +1528,12 @@
 		verbose(VERB_QUERY, "maxdepth and need more nameservers, fail");
 		return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
 	}
+	if(iq->depth > 0 && iq->target_count &&
+		iq->target_count[1] > MAX_TARGET_COUNT) {
+		verbose(VERB_QUERY, "request has exceeded the maximum "
+			"number of glue fetches %d", iq->target_count[1]);
+		return error_response_cache(qstate, id, LDNS_RCODE_SERVFAIL);
+	}
 	/* mark cycle targets for parent-side lookups */
 	iter_mark_pside_cycle_targets(qstate, iq->dp);
 	/* see if we can issue queries to get nameserver addresses */
@@ -1525,6 +1563,7 @@
 		if(query_count != 0) { /* suspend to await results */
 			verbose(VERB_ALGO, "try parent-side glue lookup");
 			iq->num_target_queries += query_count;
+			target_count_increase(iq, query_count);
 			qstate->ext_state[id] = module_wait_subquery;
 			return 0;
 		}
@@ -1680,6 +1719,7 @@
 			return error_response(qstate, id, LDNS_RCODE_SERVFAIL);
 		}
 		iq->num_target_queries += extra;
+		target_count_increase(iq, extra);
 		if(iq->num_target_queries > 0) {
 			/* wait to get all targets, we want to try em */
 			verbose(VERB_ALGO, "wait for all targets for fallback");
@@ -1720,6 +1760,7 @@
 		/* errors ignored, these targets are not strictly necessary for
 		 * this result, we do not have to reply with SERVFAIL */
 		iq->num_target_queries += extra;
+		target_count_increase(iq, extra);
 	}
 
 	/* Add the current set of unused targets to our queue. */
@@ -1765,6 +1806,7 @@
 					return 1;
 				}
 				iq->num_target_queries += qs;
+				target_count_increase(iq, qs);
 			}
 			/* Since a target query might have been made, we 
 			 * need to check again. */
@@ -2847,6 +2889,8 @@
 	iq = (struct iter_qstate*)qstate->minfo[id];
 	if(iq) {
 		outbound_list_clear(&iq->outlist);
+		if(iq->target_count && --iq->target_count[0] == 0)
+			free(iq->target_count);
 		iq->num_current_queries = 0;
 	}
 	qstate->minfo[id] = NULL;
Index: contrib/unbound/iterator/iterator.h
===================================================================
--- contrib/unbound/iterator/iterator.h.orig
+++ contrib/unbound/iterator/iterator.h
@@ -52,6 +52,8 @@
 struct iter_prep_list;
 struct iter_priv;
 
+/** max number of targets spawned for a query and its subqueries */
+#define MAX_TARGET_COUNT	32
 /** max number of query restarts. Determines max number of CNAME chain. */
 #define MAX_RESTART_COUNT       8
 /** max number of referrals. Makes sure resolver does not run away */
@@ -254,6 +256,10 @@
 
 	/** number of queries fired off */
 	int sent_count;
+	
+	/** number of target queries spawned in [1], for this query and its
+	 * subqueries, the malloced-array is shared, [0] refcount. */
+	int* target_count;
 
 	/**
 	 * The query must store NS records from referrals as parentside RRs
