Bug 914

Reported by Ken Renard:

In ns3::olsr::RoutingProtocol::RouteInput(), the 'LocalDeliverCallback lcb' parameter might be passed in as a NULL callback if the higher level routing protocol (such as ListRouting) has already delivered this packet locally as a multicast packet.  My 'fix' is simply to check to make sure that lcb.IsNull() is false before trying to call it.  Attached is a simple program that demonstrates this.

Here is a simple patch for addressing this

> --- olsr-routing-protocol.cc    (revision 468)
> +++ olsr-routing-protocol.cc    (revision 469)
> @@ -3004,7 +3004,10 @@
>   if (m_ipv4->IsDestinationAddress (dst, iif))
>     {
>         NS_LOG_LOGIC ("Local delivery to " << dst);
> -        lcb (p, header, iif);
> +        if (lcb.IsNull() == false)
> +          {
> +            lcb (p, header, iif);
> +          }
>         return true;
>     } 

The method Ipv4L3Protocol::IsDestinationAddress() is undocumented, but it clearly returns true for any multicast or broadcast; it may be better to handle unicast, broadcast, and multicast with separate methods.