function involving sending and receiving ICP

[Lan Bin]

Hi! 
IN squid 1.x, we know that
protoDispatch() in proto.c 
involves sending IP queries
and receiving ICP replies.

However, in squid 2.x,
there is not proto.c and
function protoDispatch(),
SO WHAT IS THE FUNCTION(
IN WHICH FILE) TO DO THIS
JOB?

Thanx!