Wireshark dissector : conversion of string into userdata

["Segreto, Ingrid" <Ingrid.Segreto@...>]

Hi, 

I'm working on a wireshark dissector and I have a part of my dissector that uses a C#.net dll. The objective is to decipher a part of the frame (this is done by the dll) captured by wireshark and to dissect the deciphered frame obtained. The problem is that all my dissectors functions uses a parameter called "buffer" which has a "userdata" type coming from Wireshark, and my dll returns a string.
Is there a way to convert the string into a userdata ? 

I tried to modify my dll to return a byte[] type but I was not able to use this variable like "buffer".

I also tried to send back my result on the network on localhost using (luasocket) but wireshark doesn't capture the packets in localhost. 

Thanks,

Best regards

Ingrid