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# 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 httplib
import md5
import os
import pwd
import random
import socket
import sys
import urllib
import uuid
import cjson
from common import (util, studpath)
import conf
trampoline_path = os.path.join(conf.ivle_install_dir, "bin/trampoline")
python_path = "/usr/bin/python" # Within jail
console_dir = "/opt/ivle/scripts" # Within jail
console_path = "/opt/ivle/scripts/python-console" # Within jail
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 == "chat":
handle_chat(req)
elif req.path == "block":
handle_chat(req, kind="block")
else:
req.throw_error(req.HTTP_BAD_REQUEST)
def handle_start(req):
jail_path = os.path.join(conf.jail_base, req.username)
working_dir = os.path.join("/home", req.username) # Within jail
# Get the UID of the logged-in user
try:
(_,_,uid,_,_,_,_) = pwd.getpwnam(req.username)
except KeyError:
# The user does not exist. This should have already failed the
# previous test.
req.throw_error(req.HTTP_INTERNAL_SERVER_ERROR)
# Set request attributes
req.content_type = "text/plain"
req.write_html_head_foot = False
# TODO: Figure out the host name the console server is running on.
host = socket.gethostname()
# Create magic
# TODO
magic = md5.new(uuid.uuid4().bytes).digest().encode('hex')
# Try to find a free port on the server.
# Just try some random ports in the range [3000,8000)
# until we either succeed, or give up. If you think this
# sounds risky, it isn't:
# For N ports (e.g. 5000) with k (e.g. 100) in use, the
# probability of failing to find a free port in t (e.g. 5) tries
# is (k / N) ** t (e.g. 3.2*10e-9).
tries = 0
while tries < 5:
port = int(random.uniform(3000, 8000))
# Start the console server (port, magic)
# trampoline usage: tramp uid jail_dir working_dir script_path args
# console usage: python-console port magic
# TODO: Pass working_dir as argument, let console cd to it
cmd = ' '.join([trampoline_path, str(uid), jail_path,
console_dir, python_path, console_path,
str(port), str(magic)])
print >> sys.stderr, cmd
res = os.system(cmd)
print >> sys.stderr, res
if res == 0:
# success
break;
tries += 1
if tries == 5:
raise Exception, "unable to find a free port!"
# Return port, magic
req.write(cjson.encode({"host": host, "port": port, "magic": magic}))
def handle_chat(req, kind = "chat"):
# The request *should* have the following four fields:
# host, port: Host and port where the console server apparently lives
# digest, 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)
fields = req.get_fieldstorage()
try:
host = fields.getfirst("host").value
port = int(fields.getfirst("port").value)
digest = fields.getfirst("digest").value
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
except AttributeError:
text = ""
msg = {'cmd':kind, 'text':text, 'digest':digest}
sok = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sok.connect((host, port))
sok.send(cjson.encode(msg))
buf = cStringIO.StringIO()
blk = sok.recv(1024)
while blk:
buf.write(blk)
try:
blk = conn.recv(1024, socket.MSG_DONTWAIT)
except:
# Exception thrown if it WOULD block (but we
# told it not to wait) - ie. we are done
blk = None
inp = buf.getvalue()
sok.close()
req.content_type = "text/plain"
req.write(inp)
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