~azzar1/unity/add-show-desktop-key

# IVLE - Informatics Virtual Learning Environment

# Copyright (C) 2007-2009 The University of Melbourne

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

# Author: Matt Giuca, Tom Conway, Will Grant

'''Python console RPC service.

Provides an HTTP RPC interface to a Python console process.

'''

import os

import socket

import cjson

import errno

import ivle.console

import ivle.chat

import ivle.conf

from ivle.webapp.base.rest import JSONRESTView, named_operation

from ivle.webapp.errors import BadRequest

# XXX: Should be RPC view, with actions in URL?

class ConsoleServiceRESTView(JSONRESTView):

    '''An RPC interface to a Python console.'''

    def get_permissions(self, user):

        if user is not None:

            return set(['use'])

        else:

            return set()

    @named_operation('use')

    def start(self, req, cwd=''):

        working_dir = os.path.join("/home", req.user.login, cwd)

        uid = req.user.unixid

        # Start the server

        jail_path = os.path.join(ivle.conf.jail_base, req.user.login)

        cons = ivle.console.Console(uid, jail_path, working_dir)

        # Assemble the key and return it. Yes, it is double-encoded.

        return {'key': cjson.encode({"host": cons.host,

                                     "port": cons.port,

                                     "magic": cons.magic}).encode('hex')}

    @named_operation('use')

    def chat(self, req, key, text='', kind="chat"):

        # The request *should* have the following four fields:

        # key: Hex JSON dict of host and port where the console server lives,

        # and the secret to use to digitally sign the communication with the

        # console server.

        # text: Fields to pass along to the console server

        # It simply acts as a proxy to the console server

        try:

            keydict = cjson.decode(key.decode('hex'))

            host = keydict['host']

            port = keydict['port']

            magic = keydict['magic']

        except KeyError:

            raise BadRequest("Invalid console key.")

        jail_path = os.path.join(ivle.conf.jail_base, req.user.login)

        working_dir = os.path.join("/home", req.user.login)   # Within jail

        uid = req.user.unixid

        msg = {'cmd':kind, 'text':text}

        try:

            json_response = ivle.chat.chat(host, port, msg, magic,decode=False)

            # Snoop the response from python-console to check that it's valid

            try:

                response = cjson.decode(json_response)

            except cjson.DecodeError:

                # Could not decode the reply from the python-console server

                response = {"terminate":

                    "Communication to console process lost"}

            if "terminate" in response:

                response = restart_console(uid, jail_path, working_dir,

                    response["terminate"])

        except socket.error, (enumber, estring):

            if enumber == errno.ECONNREFUSED:

                # Timeout: Restart the session

                response = restart_console(uid, jail_path, working_dir,

                    "The IVLE console has timed out due to inactivity")

            elif enumber == errno.ECONNRESET:

                # Communication issue: Restart the session

                response = restart_console(uid, jail_path, working_dir,

                    "Connection with the console has been reset")

            else:

                # Some other error - probably serious

                raise socket.error, (enumber, estring)

        return response

def restart_console(uid, jail_path, working_dir, reason):

    """Tells the client that it must be issued a new console since the old 

    console is no longer availible. The client must accept the new key.

    Returns the JSON response to be given to the client.

    """

    # Start a new console server console

    cons = ivle.console.Console(uid, jail_path, working_dir)

    # Make a JSON object to tell the browser to restart its console client

    new_key = cjson.encode(

        {"host": cons.host, "port": cons.port, "magic": cons.magic})

    return {"restart": reason, "key": new_key.encode("hex")}