cycle detection

git-svn-id: file:///svn/unbound/trunk@452 be551aaa-1e26-0410-a405-d3ace91eadb9

daemon/worker.c

@@ -712,6 +712,7 @@ worker_init(struct worker* worker, struct config_file *cfg,
 	worker->env.kill_sub = &mesh_state_delete;
 	worker->env.query_done = &mesh_query_done;
 	worker->env.walk_supers = &mesh_walk_supers;
+	worker->env.detect_cycle = &mesh_detect_cycle;
 	if(!worker->env.mesh) {
 		worker_delete(worker);
 		return 0;

doc/Changelog

@@ -1,3 +1,7 @@
+26 July 2007: Wouter
+	- cycle detection, for query state dependencies. Will attempt to
+	  circumvent the cycle, but if no other targets available fails.
+
 25 July 2007: Wouter
 	- testbound read ADDRESS and check it.
 	- test for version.bind and friends.

iterator/iter_utils.c

@@ -354,3 +354,32 @@ iter_ns_probability(struct ub_randstate* rnd, int n, int m)
 	sel = ub_random(rnd) % m; 
 	return (sel < n);
 }
+
+/** detect dependency cycle for query and target */
+static int
+causes_cycle(struct module_qstate* qstate, uint8_t* name, size_t namelen,
+	uint16_t t, uint16_t c)
+{
+	struct query_info qinf;
+	qinf.qname = name;
+	qinf.qname_len = namelen;
+	qinf.qtype = t;
+	qinf.qclass = c;
+	return (*qstate->env->detect_cycle)(qstate, &qinf);
+}
+
+void 
+iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp)
+{
+	struct delegpt_ns* ns;
+	for(ns = dp->nslist; ns; ns = ns->next) {
+		if(ns->resolved)
+			continue;
+		/* see if this ns as target causes dependency cycle */
+		if(causes_cycle(qstate, ns->name, ns->namelen, 
+			LDNS_RR_TYPE_AAAA, qstate->qinfo.qclass) ||
+		   causes_cycle(qstate, ns->name, ns->namelen, 
+			LDNS_RR_TYPE_A, qstate->qinfo.qclass))
+			ns->resolved = 1;
+	}
+}

iterator/iter_utils.h

@@ -52,6 +52,7 @@ struct msg_parse;
 struct ub_randstate;
 struct query_info;
 struct reply_info;
+struct module_qstate;
 
 /**
  * Process config options and set iterator module state.
@@ -119,4 +120,12 @@ int iter_dns_store(struct module_env* env, struct query_info* qinf,
  */
 int iter_ns_probability(struct ub_randstate* rnd, int n, int m);
 
+/**
+ * Mark targets that result in a dependency cycle as done, so they
+ * will not get selected as targets.
+ * @param qstate: query state.
+ * @param dp: delegpt to mark ns in.
+ */
+void iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp);
+
 #endif /* ITERATOR_ITER_UTILS_H */

iterator/iterator.c

@@ -811,8 +811,11 @@ query_for_targets(struct module_qstate* qstate, struct iter_qstate* iq,
 {
 	int query_count = 0;
 	struct delegpt_ns* ns = iq->dp->nslist;
-	int missing = (int)delegpt_count_missing_targets(iq->dp);
+	int missing;
 	int toget = 0;
+
+	iter_mark_cycle_targets(qstate, iq->dp);
+	missing = (int)delegpt_count_missing_targets(iq->dp);
 	log_assert(maxtargets != 0); /* that would not be useful */
 
 	/* Generate target requests. Basically, any missing targets 
@@ -840,13 +843,6 @@ query_for_targets(struct module_qstate* qstate, struct iter_qstate* iq,
 			missing --;
 			continue;
 		}
-		if(iq->refetch_glue && dname_subdomain_c(ns->name, 
-			iq->dp->name)) {
-			log_nametypeclass(VERB_DETAIL, "skip double glue "
-				"refetch", ns->name, LDNS_RR_TYPE_A, 
-				iq->qchase.qclass);
-			continue;
-		}
 
 		if(ie->supports_ipv6) {
 			/* Send the AAAA request. */

services/mesh.c

@@ -588,3 +588,28 @@ mesh_get_mem(struct mesh_area* mesh)
 	}
 	return s;
 }
+
+/** helper recursive rbtree find routine */
+static int
+find_in_subsub(struct mesh_state* m, struct mesh_state* tofind)
+{
+	struct mesh_state_ref* r;
+	RBTREE_FOR(r, struct mesh_state_ref*, &m->sub_set) {
+		if(r->s == tofind || find_in_subsub(r->s, tofind))
+			return 1;
+	}
+	return 0;
+}
+
+int 
+mesh_detect_cycle(struct module_qstate* qstate, struct query_info* qinfo)
+{
+	struct mesh_area* mesh = qstate->env->mesh;
+	struct mesh_state* cyc_m = qstate->mesh_info;
+	struct mesh_state* dep_m = mesh_area_find(mesh, qinfo, BIT_RD, 0);
+	if(!dep_m)
+		return 0;
+	if(dep_m == cyc_m || find_in_subsub(dep_m, cyc_m))
+		return 1;
+	return 0;
+}

services/mesh.h

@@ -357,4 +357,15 @@ void mesh_stats(struct mesh_area* mesh, const char* str);
  */
 size_t mesh_get_mem(struct mesh_area* mesh);
 
+/**
+ * Find cycle; see if the given mesh is in the targets sub, or sub-sub, ...
+ * trees.
+ * @param qstate: given mesh querystate.
+ * @param qinfo: query info for dependency.
+ * @return true if the name,type,class exists and the given qstate mesh exists
+ * 	as a dependency of that name. Thus if qstate becomes dependent on
+ * 	name,type,class then a cycle is created.
+ */
+int mesh_detect_cycle(struct module_qstate* qstate, struct query_info* qinfo);
+
 #endif /* SERVICES_MESH_H */

util/module.h

@@ -196,6 +196,20 @@ struct module_env {
 	void (*walk_supers)(struct module_qstate* qstate, int id, 
 		void (*cb)(struct module_qstate*, int, struct module_qstate*));
 
+	/**
+	 * Detect if adding a dependency for qstate on name,type,class will
+	 * create a dependency cycle.
+	 * @param qstate: given mesh querystate.
+	 * @param qinfo: query info for dependency. Assumed RDflag and not
+	 * 	priming.
+	 * @return true if the name,type,class exists and the given 
+	 * 	qstate mesh exists as a dependency of that name. Thus 
+	 * 	if qstate becomes dependent on name,type,class then a 
+	 * 	cycle is created.
+	 */
+	int (*detect_cycle)(struct module_qstate* qstate, 
+		struct query_info* qinfo);
+
 	/** region for temporary usage. May be cleared after operate() call. */
 	struct region* scratch;
 	/** internal data for daemon - worker thread. */