Protect expiration against clock stepping.

neighbour.c

@@ -247,6 +247,7 @@ check_neighbours()
         changed = update_neighbour(&neighs[i], -1, 0);
 
         if(neighs[i].reach == 0 ||
+           neighs[i].hello_time.tv_sec > now.tv_sec || /* clock stepped */
            timeval_minus_msec(&now, &neighs[i].hello_time) > 300000) {
             flush_neighbour(&neighs[i]);
             continue;

route.c

@@ -636,7 +636,8 @@ expire_routes(void)
     while(i < numroutes) {
         struct route *route = &routes[i];
 
-        if(route->time < now.tv_sec - route_gc_delay) {
+        if(route->time > now.tv_sec || /* clock stepped */
+           route->time < now.tv_sec - route_gc_delay) {
             flush_route(route);
             continue;
         }

source.c

@@ -166,6 +166,9 @@ expire_sources()
     for(i = 0; i < numsrcs; i++) {
         if(!srcs[i].valid)
             continue;
+        if(srcs[i].time > now.tv_sec)
+            /* clock stepped */
+            srcs[i].time = now.tv_sec;
         if(srcs[i].time < now.tv_sec - SOURCE_GC_TIME)
             continue;
         rc = flush_source(&srcs[i]);