gen_server and gen_tcp messages

[Andrew Lentvorski]

How do I make a gen_server compatible with receiving messages from gen_tcp?

What I would like to do is packetize a TCP stream.  I want this to be 
encapsulated into a server so that I just send packets and receive 
packets to the server which handles the rest of the underlying issues.

The problem I have is that I need a receive loop in the gen_server in 
order to grab the gen_tcp messages.  Currently, I wind up with a 
gen_server which the spawns off another process solely to handle the 
gen_tcp messages.  The gen_server and the tcp grab process then have to 
handle bidi coordination messages just like are already implemented by 
gen_server.  This seems ... wrong.  I have almost certainly made a poor 
architectural decision somewhere.

Is there a way to convince the gen_server to call some code when it gets 
a gen_tcp message or message which it doesn't recognize?  Basically I 
need to splice some extra message handling code into the existing 
gen_server receive loop.

Thanks,
-a