Drop routes when overflowing the route table.

route.c

@@ -309,6 +309,49 @@ update_network_metric(struct network *net)
     }
 }
 
+/* We're overflowing the route table.  Find some hopefully useless
+   routes and drop them. */
+static void
+drop_some_routes(void)
+{
+    int i;
+
+    i = 0;
+    while(i < numroutes) {
+        if(!routes[i].installed && routes[i].time < now.tv_sec - 90) {
+            flush_route(&routes[i]);
+            continue;
+        }
+        
+        if(routes[i].metric >= INFINITY && routes[i].time < now.tv_sec - 90) {
+            flush_route(&routes[i]);
+            continue;
+        }
+    }
+
+    if(numroutes < MAXROUTES)
+        return;
+
+    /* We didn't manage to free a table entry just by dropping useless
+       routes.  Let's take more drastic action. */
+
+    for(i = 0; i < numroutes; i++) {
+        if(!route_feasible(&routes[i])) {
+            flush_route(&routes[i]);
+            return;
+        }
+    }
+
+    for(i = 0; i < numroutes; i++) {
+        if(!routes[i].installed) {
+            flush_route(&routes[i]);
+            return;
+        }
+    }
+
+    return;
+}
+
 /* This is called whenever we receive an update. */
 struct route *
 update_route(const unsigned char *a, const unsigned char *p, unsigned char plen,
@@ -388,6 +431,8 @@ update_route(const unsigned char *a, const unsigned char *p, unsigned char plen,
         if(refmetric >= INFINITY)
             /* Somebody's retracting a route we never saw. */
             return NULL;
+        if(numroutes >= MAXROUTES)
+            drop_some_routes();
         if(numroutes >= MAXROUTES) {
             fprintf(stderr, "Too many routes -- ignoring update.\n");
             return NULL;