"Chesting up" to a shooting player

Originally posted by MattRef
I am curious about something. Here is my example: a player is making a drive for the basket. The defensive player, while his hands are in the air straight up, is bumping the driving offensive player with his chest. Is this a block, a push, or a no call? Thanks!
Matt

I guess I would need to know if legal guarding position was established, but i have a no-call as long as the defender doesn't displace the dribbler.