Is server the sender of RPC?

I need to perform a check to see if the RPC has been sent by the server itself. Never trust s client y'know.

Normally to test the RPC sender against a player i'd do this:

 [RPC]
 public void DisablePhysics(NetworkMessageInfo info) {
     if (info.sender == networkView.owner) RigidbodyConstraints.FreezeAll;
 }

But how do I test to see if the sender is the server? Passing a bool won't do as any client would be able to do so as well.