Be smarter about forwarding requests.

If our currently selected nexthop sends us a request, we should not
forward it back, but rather try a different route.

message.c

@@ -267,7 +267,10 @@ handle_request(struct neighbour *neigh, const unsigned char *prefix,
     }
 
     route = find_installed_route(prefix, plen);
-    if(route && route->metric < INFINITY) {
+    if(!route || route->metric >= INFINITY || route->neigh == neigh)
+        route = find_best_route(prefix, plen, 0);
+    if(!route || route->metric >= INFINITY || route->neigh == neigh)
+        return;
     if(router_hash == hash_id(route->src->address) &&
        seqno_compare(seqno, route->seqno) > 0) {
         if(hop_count > 1) {
@@ -280,7 +283,6 @@ handle_request(struct neighbour *neigh, const unsigned char *prefix,
         send_update(neigh->network, 1, prefix, plen);
     }
     return;
-    }
 }