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

# IVLE

# Copyright (C) 2007-2008 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

# App: consoleservice

# Author: Matt Giuca, Tom Conway

# Date: 14/1/2008

import cStringIO

import md5

import os

import random

import socket

import sys

import uuid

import cjson

from ivle import (util, studpath, chat, console)

import ivle.conf

import errno

def handle(req):

    """Handler for the Console Service AJAX backend application."""

    if len(req.path) > 0 and req.path[-1] == os.sep:

        path = req.path[:-1]

    else:

        path = req.path

    # The path determines which "command" we are receiving

    if req.path == "start":

        handle_start(req)

    elif req.path == "interrupt":

        handle_chat(req, kind='interrupt')

    elif req.path == "restart":

        handle_chat(req, kind='terminate')

    elif req.path == "chat":

        handle_chat(req)

    elif req.path == "block":

        handle_chat(req, kind="block")

    elif req.path == "flush":

        handle_chat(req, kind="flush")

    elif req.path == "inspect":

        handle_chat(req, kind="inspect")

    else:

        req.throw_error(req.HTTP_BAD_REQUEST)

def handle_start(req):

    # Changes the state on the server - must be POST

    if req.method != "POST":

        req.throw_error(req.HTTP_BAD_REQUEST)

    # See if we have been given extra params

    fields = req.get_fieldstorage()

    try:

        startdir = fields.getfirst("startdir").value

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

    except AttributeError:

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

    # Get the UID of the logged-in user

    uid = req.user.unixid

    # Set request attributes

    req.content_type = "text/plain"

    req.write_html_head_foot = False

    # Start the server

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

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

    # Assemble the key and return it.

    key = cjson.encode(

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

    req.write(cjson.encode({"key": key.encode("hex")}))

def handle_chat(req, kind = "chat"):

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

    # host, port, magic: 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

    if req.method != "POST":

        req.throw_error(req.HTTP_BAD_REQUEST)

    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

    fields = req.get_fieldstorage()

    try:

        key = cjson.decode(fields.getfirst("key").value.decode("hex"))

        host = key['host']

        port = key['port']

        magic = key['magic']

    except AttributeError:

        # Any of the getfirsts returned None

        req.throw_error(req.HTTP_BAD_REQUEST)

    # If text is None, it was probably just an empty line

    try:

        text = fields.getfirst("text").value.decode('utf-8')

    except AttributeError:

        text = ""

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

    try:

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

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

        try:

            decoded_response = cjson.decode(response)

        except cjson.DecodeError:

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

            decoded_response = {"terminate":

                "Communication to console process lost"}

        if "terminate" in decoded_response:

            response = restart_console(uid, jail_path, working_dir,

                decoded_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)

    req.content_type = "text/plain"

    req.write(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 = 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})

    json_restart = {

        "restart": reason,

        "key": new_key.encode("hex"),

    }

    return cjson.encode(json_restart)