From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Tue,  9 Apr 1996 09:39:45 -0400
From: Hans-Peter Bischof bischof@informatik.Uni-Osnabrueck.DE
Subject: 9P & spy
Topicbox-Message-UUID: 42b2251a-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19960409133945.hhqwKXkVd7-33gXbdt5VviyoHOawmhiE-EGzluYjwsA@z>



                               Old spies revisited

        The Tee

        With the same strategy as inserting tee in a shell  pipeline  one
        can track the 9P data stream between server and kernel.

        Our programm, spy, receives the  9P  messages  from  the  kernel,
        displays  them  for modification and sends the resulting messages
        to the intended server.  In the same way  spy  transmits  the  9P
        replies of the server.  Data spied out in this manner can be used
        in many different ways.

        The entire approach is transparent to both, the  client  and  the
        server.   spy  is  mounted onto the dormant server connection and
        offers its own connection to  the  client  instead.   The  client
        believes  it  is  mounting  the  server,  when,  in  fact,  it is
        connecting to spy.  The server views spy as its client.

        Spy

        Spy realizes a tee in form of a 9P  information  flow  inspector.
        It displays the flow of the 9P messages between server and client
        in a graphic representation.  The user is able to  specify  in  a
        filter  language,  which  9P  messages should be observed.  It is
        possible to watch seperatly each request and reply message or  to
        set  watch points on the arrival of dedicated messages.  Moreover
        it is possible to modify each message or pass own  messages  into
        the 9P data stream.

        A graphical user interface helps the user with the modifications.

        If you are interessted: ftp.informatik.uni-osnabrueck.de
                                pub/plan/spy.tar   (includes [28kv].spy)

        Hans-Peter Bischof, Bernd Kuehl
        University of Osnabrueck
        bischof@informatik.Uni-Osnabrueck.DE