[clusterer] Added enable_rerouting parameter

 When "enable_rerouting" is set to 0, packet will never be rerouted via other nodes.
 This is useful for situations where network issues are unlikely (LAN) or when only
 two nodes are present.

modules/clusterer/clusterer.c

@@ -56,6 +56,7 @@ extern int node_timeout;
 extern int ping_timeout;
 extern int seed_fb_interval;
 extern int sync_timeout;
+extern int clusterer_enable_rerouting;
 
 int dispatch_jobs = 1;
 
@@ -1076,6 +1077,10 @@ void bin_rcv_cl_extra_packets(bin_packet_t *packet, int packet_type,
 		lock_release(node->lock);
 
 	if (dest_id != current_id) {
+		if (clusterer_enable_rerouting == 0) {
+			LM_WARN("Received message for destination id [%d] but rerouting disabled\n", dest_id);
+			goto exit;
+		}
 		/* route the message */
 		bin_push_int(packet, cluster_id);
 		bin_push_int(packet, source_id);

modules/clusterer/clusterer_mod.c

@@ -48,6 +48,7 @@ int seed_fb_interval = DEFAULT_SEED_FB_INTERVAL;
 int sync_timeout = DEFAULT_SYNC_TIMEOUT;
 int current_id = -1;
 int db_mode = 1;
+int clusterer_enable_rerouting = 1;
 
 str clusterer_db_url = {NULL, 0};
 str db_table = str_init("clusterer");
@@ -171,6 +172,7 @@ static const param_export_t params[] = {
 		(void*)&shtag_modparam_func},
 	{"sync_packet_size",	INT_PARAM,	&sync_packet_size	},
 	{"dispatch_jobs",		INT_PARAM,	&dispatch_jobs		},
+	{"enable_rerouting",		INT_PARAM,	&clusterer_enable_rerouting	},
 	{0, 0, 0}
 };
 

modules/clusterer/doc/clusterer_admin.xml

@@ -639,6 +639,29 @@ modparam("clusterer", "description_col", "description")
 				<programlisting format="linespecific">
 ...
 modparam("clusterer", "enable_stats", 0)
+...
+				</programlisting>
+			</example>
+		</section>
+
+		<section id="param_enable_rerouting" xreflabel="enable_rerouting">
+			<title><varname>enable_rerouting</varname> (integer)</title>
+			<para>
+				If packets should be rerouted via another node if a direct route
+				to destination is unavailible. Disabling may improve stability in
+				two-node topologies.
+				Set it to zero to disable or to non-zero to enable it.
+			</para>
+			<para>
+				<emphasis>
+					Default value is <quote>1 (enabled)</quote>.
+				</emphasis>
+			</para>
+			<example>
+				<title>Set <varname>enable_rerouting</varname> parameter</title>
+				<programlisting format="linespecific">
+...
+modparam("clusterer", "enable_rerouting", 0)
 ...
 				</programlisting>
 			</example>

modules/clusterer/topology.c

@@ -29,6 +29,7 @@
 extern int ping_interval;
 extern int node_timeout;
 extern int ping_timeout;
+extern int clusterer_enable_rerouting;
 
 #define PING_REPLY_INTERVAL(_node) \
 	((_node)->last_pong.tv_sec*1000000 + (_node)->last_pong.tv_usec \
@@ -313,12 +314,16 @@ node_info_t *get_next_hop_2(node_info_t *dest)
 {
 	node_info_t *n, *next_hop;
 	struct node_search_info *queue_front;
-    struct node_search_info *root, *curr;
-    struct neighbour *neigh;
+	struct node_search_info *root, *curr;
+	struct neighbour *neigh;
+
+	if (clusterer_enable_rerouting == 0) {
+		return NULL;
+	}
 
-    lock_get(dest->cluster->lock);
+	lock_get(dest->cluster->lock);
 
-    /* run BFS */
+	/* run BFS */
 	if (dest->cluster->top_version != dest->sp_top_version) {
 		lock_get(dest->lock);
 		dest->next_hop = NULL;
@@ -398,6 +403,10 @@ int get_next_hop(node_info_t *dest)
 {
 	node_info_t *nhop;
 
+	if (clusterer_enable_rerouting == 0) {
+		return 0;
+	}
+
 	lock_get(dest->lock);
 
 	if (dest->link_state == LS_UP) {
@@ -909,7 +918,9 @@ int set_link_w_neigh(clusterer_link_state new_ls, node_info_t *neigh)
 			check_node_events(neigh, CLUSTER_NODE_UP);
 			lock_get(neigh->lock);
 		}
-		neigh->next_hop = neigh;
+		if (clusterer_enable_rerouting) {
+			neigh->next_hop = neigh;
+		}
 
 	}