There are a couple of new packet types in the frisbee protocol which are
exchanged via TCP with the master server: GETREQUEST and GETREPLY.  The
client passes to the master server an opaque imageid and a couple of options
and gets back the addr/port to use to actually download the image.  The
implementation of the master server is fragile and is more of a test
framework, Grant is working on a more robust master server.  I am mostly
doing a backend that communicates with the Emulab DB to do its authentication
and making the client changes.

The client now uses the -S option to specify the IP address of the master
server and the -F option to specify an imageid.  If no error is returned,
the image is downloaded using the returned addr/port.  If -Q is used in place
of -F, then the client makes a "status only" call getting back info about
whether the named image is accessible to the client and whether a server is
currently running.
...