hi,
I'm a new guy in this forum.these days I have been
learning the code for a deep understading of the
BT-Kademlia net.
the question is:
what the interface of search? I do know a function"FindNode(Key)"
in dht.h, but I didn't see which class used it?

To find peers for a torrent the announce function is used. This is called from DHTTrackerBackend::doRequest.