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# 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
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, config):
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(req.config['paths']['jails']['mounts'],
req.user.login)
cons = ivle.console.Console(req.config, 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='', cwd='', 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(req.config['paths']['jails']['mounts'],
req.user.login)
# Within Jail
working_dir = os.path.join("/home", req.user.login, cwd)
uid = req.user.unixid
# XXX: JSONRESTView should do this for us.
text = text.decode('utf-8')
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(req.config, uid, jail_path,
working_dir, response["terminate"])
except socket.error, (enumber, estring):
if enumber == errno.ECONNREFUSED:
# Timeout: Restart the session
response = restart_console(req.config, 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(req.config, 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(config, 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(config, 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")}
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