cpython/Demo/rpc/mountclient.py

# Mount RPC client -- RFC 1094 (NFS), Appendix A

# This module demonstrates how to write your own RPC client in Python.
# When this example was written, there was no RPC compiler for
# Python. Without such a compiler, you must first create classes
# derived from Packer and Unpacker to handle the data types for the
# server you want to interface to.  You then write the client class.
# If you want to support both the TCP and the UDP version of a
# protocol, use multiple inheritance as shown below.


import rpc
from rpc import Packer, Unpacker, TCPClient, UDPClient


# Program number and version for the mount protocol
MOUNTPROG = 100005
MOUNTVERS = 1

# Size of the 'fhandle' opaque structure
FHSIZE = 32


# Packer derived class for Mount protocol clients.
# The only thing we need to pack beyond basic types is an 'fhandle'

class MountPacker(Packer):

    def pack_fhandle(self, fhandle):
        self.pack_fopaque(FHSIZE, fhandle)


# Unpacker derived class for Mount protocol clients.
# The important types we need to unpack are fhandle, fhstatus,
# mountlist and exportlist; mountstruct, exportstruct and groups are
# used to unpack components of mountlist and exportlist and the
# corresponding functions are passed as function argument to the
# generic unpack_list function.

class MountUnpacker(Unpacker):

    def unpack_fhandle(self):
        return self.unpack_fopaque(FHSIZE)

    def unpack_fhstatus(self):
        status = self.unpack_uint()
        if status == 0:
            fh = self.unpack_fhandle()
        else:
            fh = None
        return status, fh

    def unpack_mountlist(self):
        return self.unpack_list(self.unpack_mountstruct)

    def unpack_mountstruct(self):
        hostname = self.unpack_string()
        directory = self.unpack_string()
        return (hostname, directory)

    def unpack_exportlist(self):
        return self.unpack_list(self.unpack_exportstruct)

    def unpack_exportstruct(self):
        filesys = self.unpack_string()
        groups = self.unpack_groups()
        return (filesys, groups)

    def unpack_groups(self):
        return self.unpack_list(self.unpack_string)


# These are the procedures specific to the Mount client class.
# Think of this as a derived class of either TCPClient or UDPClient.

class PartialMountClient:

    # This method is called by Client.__init__ to initialize
    # self.packer and self.unpacker
    def addpackers(self):
        self.packer = MountPacker()
        self.unpacker = MountUnpacker('')

    # This method is called by Client.__init__ to bind the socket
    # to a particular network interface and port.  We use the
    # default network interface, but if we're running as root,
    # we want to bind to a reserved port
    def bindsocket(self):
        import os
        try:
            uid = os.getuid()
        except AttributeError:
            uid = 1
        if uid == 0:
            port = rpc.bindresvport(self.sock, '')
            # 'port' is not used
        else:
            self.sock.bind(('', 0))

    # This function is called to cough up a suitable
    # authentication object for a call to procedure 'proc'.
    def mkcred(self):
        if self.cred == None:
            self.cred = rpc.AUTH_UNIX, rpc.make_auth_unix_default()
        return self.cred

    # The methods Mnt, Dump etc. each implement one Remote
    # Procedure Call.  This is done by calling self.make_call()
    # with as arguments:
    #
    # - the procedure number
    # - the arguments (or None)
    # - the "packer" function for the arguments (or None)
    # - the "unpacker" function for the return value (or None)
    #
    # The packer and unpacker function, if not None, *must* be
    # methods of self.packer and self.unpacker, respectively.
    # A value of None means that there are no arguments or is no
    # return value, respectively.
    #
    # The return value from make_call() is the return value from
    # the remote procedure call, as unpacked by the "unpacker"
    # function, or None if the unpacker function is None.
    #
    # (Even if you expect a result of None, you should still
    # return the return value from make_call(), since this may be
    # needed by a broadcasting version of the class.)
    #
    # If the call fails, make_call() raises an exception
    # (this includes time-outs and invalid results).
    #
    # Note that (at least with the UDP protocol) there is no
    # guarantee that a call is executed at most once.  When you do
    # get a reply, you know it has been executed at least once;
    # when you don't get a reply, you know nothing.

    def Mnt(self, directory):
        return self.make_call(1, directory, \
                self.packer.pack_string, \
                self.unpacker.unpack_fhstatus)

    def Dump(self):
        return self.make_call(2, None, \
                None, self.unpacker.unpack_mountlist)

    def Umnt(self, directory):
        return self.make_call(3, directory, \
                self.packer.pack_string, None)

    def Umntall(self):
        return self.make_call(4, None, None, None)

    def Export(self):
        return self.make_call(5, None, \
                None, self.unpacker.unpack_exportlist)


# We turn the partial Mount client into a full one for either protocol
# by use of multiple inheritance.  (In general, when class C has base
# classes B1...Bn, if x is an instance of class C, methods of x are
# searched first in C, then in B1, then in B2, ..., finally in Bn.)

class TCPMountClient(PartialMountClient, TCPClient):

    def __init__(self, host):
        TCPClient.__init__(self, host, MOUNTPROG, MOUNTVERS)


class UDPMountClient(PartialMountClient, UDPClient):

    def __init__(self, host):
        UDPClient.__init__(self, host, MOUNTPROG, MOUNTVERS)


# A little test program for the Mount client.  This takes a host as
# command line argument (default the local machine), prints its export
# list, and attempts to mount and unmount each exported files system.
# An optional first argument of -t or -u specifies the protocol to use
# (TCP or UDP), default is UDP.

def test():
    import sys
    if sys.argv[1:] and sys.argv[1] == '-t':
        C = TCPMountClient
        del sys.argv[1]
    elif sys.argv[1:] and sys.argv[1] == '-u':
        C = UDPMountClient
        del sys.argv[1]
    else:
        C = UDPMountClient
    if sys.argv[1:]: host = sys.argv[1]
    else: host = ''
    mcl = C(host)
    list = mcl.Export()
    for item in list:
        print item
        try:
            mcl.Mnt(item[0])
        except:
            print 'Sorry'
            continue
        mcl.Umnt(item[0])