Hopefully i understand your question correctly.
There are 2 ways to answer your question:
1) Your openvpn-server is listening on some UDP port, say 1194. TCP packets send to port 1194 (that is, external ip-address of the server and TCP port 1194) are rejected by the ip-stack of the server: There's nobody listeing on TCP-1194. No wrapping or whatsoever is done.
2) Inside the tunnel is a different situation. I wrote
an explaination some time ago how that works.
Hope this helps