| 1 | Filesystem, RCS and CVS client and server classes
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| 2 | =================================================
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| 3 |
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| 4 | *** See the security warning at the end of this file! ***
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| 5 |
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| 6 | This directory contains various modules and classes that support
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| 7 | remote file system operations.
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| 8 |
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| 9 | CVS stuff
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| 10 | ---------
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| 11 |
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| 12 | rcvs Script to put in your bin directory
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| 13 | rcvs.py Remote CVS client command line interface
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| 14 |
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| 15 | cvslib.py CVS admin files classes (used by rrcs)
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| 16 | cvslock.py CVS locking algorithms
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| 17 |
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| 18 | RCS stuff
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| 19 | ---------
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| 20 |
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| 21 | rrcs Script to put in your bin directory
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| 22 | rrcs.py Remote RCS client command line interface
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| 23 |
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| 24 | rcsclient.py Return an RCSProxyClient instance
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| 25 | (has reasonable default server/port/directory)
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| 26 |
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| 27 | RCSProxy.py RCS proxy and server classes (on top of rcslib.py)
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| 28 |
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| 29 | rcslib.py Local-only RCS base class (affects stdout &
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| 30 | local work files)
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| 31 |
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| 32 | FSProxy stuff
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| 33 | -------------
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| 34 |
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| 35 | sumtree.py Old demo for FSProxy
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| 36 | cmptree.py First FSProxy client (used to sync from the Mac)
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| 37 | FSProxy.py Filesystem interface classes
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| 38 |
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| 39 | Generic client/server stuff
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| 40 | ---------------------------
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| 41 |
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| 42 | client.py Client class
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| 43 | server.py Server class
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| 44 |
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| 45 | security.py Security mix-in class (not very secure I think)
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| 46 |
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| 47 | Other generic stuff
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| 48 | -------------------
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| 49 |
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| 50 | cmdfw.py CommandFrameWork class
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| 51 | (used by rcvs, should be used by rrcs as well)
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| 52 |
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| 53 |
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| 54 | Client/Server operation
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| 55 | -----------------------
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| 56 |
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| 57 | The Client and Server classes implement a simple-minded RPC protocol,
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| 58 | using Python's pickle module to transfer arguments, return values and
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| 59 | exceptions with the most generality. The Server class is instantiated
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| 60 | with a port number on which it should listen for requests; the Client
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| 61 | class is instantiated with a host name and a port number where it
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| 62 | should connect to. Once a client is connected, a TCP connection is
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| 63 | maintained between client and server.
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| 64 |
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| 65 | The Server class currently handles only one connection at a time;
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| 66 | however it could be rewritten to allow various modes of operations,
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| 67 | using multiple threads or processes or the select() system call as
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| 68 | desired to serve multiple clients simultaneously (when using select(),
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| 69 | still handling one request at a time). This would not require
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| 70 | rewriting of the Client class. It may also be possible to adapt the
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| 71 | code to use UDP instead of TCP, but then both classes will have to be
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| 72 | rewritten (and unless extensive acknowlegements and request serial
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| 73 | numbers are used, the server should handle duplicate requests, so its
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| 74 | semantics should be idempotent -- shrudder).
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| 75 |
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| 76 | Even though the FSProxy and RCSProxy modules define client classes,
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| 77 | the client class is fully generic -- what methods it supports is
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| 78 | determined entirely by the server. The server class, however, must be
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| 79 | derived from. This is generally done as follows:
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| 80 |
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| 81 | from server import Server
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| 82 | from client import Client
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| 83 |
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| 84 | # Define a class that performs the operations locally
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| 85 | class MyClassLocal:
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| 86 | def __init__(self): ...
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| 87 | def _close(self): ...
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| 88 |
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| 89 | # Derive a server class using multiple inheritance
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| 90 | class MyClassServer(MyClassLocal, Server):
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| 91 | def __init__(self, address):
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| 92 | # Must initialize MyClassLocal as well as Server
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| 93 | MyClassLocal.__init__(self)
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| 94 | Server.__init__(self, address)
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| 95 | def _close(self):
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| 96 | Server._close()
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| 97 | MyClassLocal._close()
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| 98 |
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| 99 | # A dummy client class
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| 100 | class MyClassClient(Client): pass
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| 101 |
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| 102 | Note that because MyClassLocal isn't used in the definition of
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| 103 | MyClassClient, it would actually be better to place it in a separate
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| 104 | module so the definition of MyClassLocal isn't executed when we only
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| 105 | instantiate a client.
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| 106 |
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| 107 | The modules client and server should probably be renamed to Client and
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| 108 | Server in order to match the class names.
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| 109 |
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| 110 |
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| 111 | *** Security warning: this version requires that you have a file
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| 112 | $HOME/.python_keyfile at the server and client side containing two
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| 113 | comma- separated numbers. The security system at the moment makes no
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| 114 | guarantees of actuallng being secure -- however it requires that the
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| 115 | key file exists and contains the same numbers at both ends for this to
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| 116 | work. (You can specify an alternative keyfile in $PYTHON_KEYFILE).
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| 117 | Have a look at the Security class in security.py for details;
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| 118 | basically, if the key file contains (x, y), then the security server
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| 119 | class chooses a random number z (the challenge) in the range
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| 120 | 10..100000 and the client must be able to produce pow(z, x, y)
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| 121 | (i.e. z**x mod y).
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