add handover window to router contact updating

llarp/router/router.cpp

@@ -1266,7 +1266,7 @@ namespace llarp
     // remove stale routers
     nodedb()->VisitInsertedAfter(
         [&](const RouterContact &rc) { removeStale.insert(rc.pubkey); },
-        ((RouterContact::UpdateInterval * 3) / 2) + now);
+        (RouterContact::UpdateInterval + now + RouterContact::UpdateWindow));
     nodedb()->RemoveIf([removeStale](const RouterContact &rc) -> bool {
       return removeStale.count(rc.pubkey) > 0;
     });

llarp/router_contact.cpp

@@ -33,6 +33,8 @@ namespace llarp
 #endif
   /// every 30 minutes an RC is stale and needs updating
   llarp_time_t RouterContact::UpdateInterval = 30 * 60 * 1000;
+  // 1 minute window for update
+  llarp_time_t RouterContact::UpdateWindow = 60 * 1000;
 
   NetID::NetID(const byte_t *val) : AlignedBuffer< 8 >()
   {

llarp/router_contact.hpp

@@ -70,6 +70,7 @@ namespace llarp
 
     static llarp_time_t Lifetime;
     static llarp_time_t UpdateInterval;
+    static llarp_time_t UpdateWindow;
 
     RouterContact()
     {