XML RPC call 1 method before all others

[eluser]asciiCode[/eluser]
I have xml rpc working fine with code igniter.

What I want to do is call one method at the start of any xml rpc method.

This new special method would validate if the version number of the xml rpc call is valid.

Please note that I pass in the version number as the first variable to all of my xmlrpc calls.

Is there an easy way to validate this information other than doing it in each individual method?