~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, Will Grant

"""

This is a mod_python handler program. The correct way to call it is to have

Apache send all requests to be handled by the module 'dispatch'.

Top-level handler. Handles all requests to all pages in IVLE.

Handles authentication (not authorization).

Then passes the request along to the appropriate ivle app.

"""

import sys

import os

import os.path

import urllib

import cgi

import traceback

import logging

import socket

import time

import mod_python

import routes

from ivle import util

import ivle.conf

from ivle.dispatch.request import Request

import ivle.webapp.security

from ivle.webapp.base.plugins import ViewPlugin, PublicViewPlugin

from ivle.webapp.errors import HTTPError, Unauthorized

def generate_route_mapper(view_plugins, attr):

    """

    Build a Mapper object for doing URL matching using 'routes', based on the

    given plugin registry.

    """

    m = routes.Mapper(explicit=True)

    for plugin in view_plugins:

        # Establish a URL pattern for each element of plugin.urls

        assert hasattr(plugin, 'urls'), "%r does not have any urls" % plugin 

        for url in getattr(plugin, attr):

            routex = url[0]

            view_class = url[1]

            kwargs_dict = url[2] if len(url) >= 3 else {}

            m.connect(routex, view=view_class, **kwargs_dict)

    return m

def handler(req):

    """Handles a request which may be to anywhere in the site except media.

    Intended to be called by mod_python, as a handler.

    req: An Apache request object.

    """

    # Make the request object into an IVLE request which can be passed to apps

    apachereq = req

    try:

        req = Request(req)

    except Exception:

        # Pass the apachereq to error reporter, since ivle req isn't created

        # yet.

        handle_unknown_exception(apachereq, *sys.exc_info())

        # Tell Apache not to generate its own errors as well

        return mod_python.apache.OK

    # Run the main handler, and catch all exceptions

    try:

        return handler_(req, apachereq)

    except mod_python.apache.SERVER_RETURN:

        # An apache error. We discourage these, but they might still happen.

        # Just raise up.

        raise

    except Exception:

        handle_unknown_exception(req, *sys.exc_info())

        # Tell Apache not to generate its own errors as well

        return mod_python.apache.OK

def handler_(req, apachereq):

    """

    Nested handler function. May raise exceptions. The top-level handler is

    just used to catch exceptions.

    Takes both an IVLE request and an Apache req.

    """

    # Hack? Try and get the user login early just in case we throw an error

    # (most likely 404) to stop us seeing not logged in even when we are.

    if not req.publicmode:

        user = ivle.webapp.security.get_user_details(req)

        # Don't set the user if it is disabled or hasn't accepted the ToS.

        if user and user.valid:

            req.user = user

    conf = ivle.config.Config()

    req.config = conf

    if req.publicmode:

        req.mapper = generate_route_mapper(conf.plugin_index[PublicViewPlugin],

                                           'public_urls')

    else:

        req.mapper = generate_route_mapper(conf.plugin_index[ViewPlugin],

                                           'urls')

    matchdict = req.mapper.match(req.uri)

    if matchdict is not None:

        viewcls = matchdict['view']

        # Get the remaining arguments, less 'view', 'action' and 'controller'

        # (The latter two seem to be built-in, and we don't want them).

        kwargs = matchdict.copy()

        del kwargs['view']

        try:

            # Instantiate the view, which should be a BaseView class

            view = viewcls(req, **kwargs)

            # Check that the request (mainly the user) is permitted to access

            # the view.

            if not view.authorize(req):

                raise Unauthorized()

            # Render the output

            view.render(req)

        except HTTPError, e:

            # A view explicitly raised an HTTP error. Respect it.

            req.status = e.code

            # Try to find a custom error view.

            if hasattr(viewcls, 'get_error_view'):

                errviewcls = viewcls.get_error_view(e)

            else:

                errviewcls = None

            if errviewcls:

                errview = errviewcls(req, e)

                errview.render(req)

                return req.OK

            elif e.message:

                req.write(e.message)

                return req.OK

            else:

                return e.code

        except Exception, e:

            # A non-HTTPError appeared. We have an unknown exception. Panic.

            handle_unknown_exception(req, *sys.exc_info())

            return req.OK

        else:

            req.store.commit()

            return req.OK

    else:

        return req.HTTP_NOT_FOUND # TODO: Prettify.

def handle_unknown_exception(req, exc_type, exc_value, exc_traceback):

    """

    Given an exception that has just been thrown from IVLE, print its details

    to the request.

    This is a full handler. It assumes nothing has been written, and writes a

    complete HTML page.

    req: May be EITHER an IVLE req or an Apache req.

    The handler code may pass an apache req if an exception occurs before

    the IVLE request is created.

    """

    req.content_type = "text/html"

    logfile = os.path.join(ivle.conf.log_path, 'ivle_error.log')

    logfail = False

    # For some reason, some versions of mod_python have "_server" instead of

    # "main_server". So we check for both.

    try:

        admin_email = mod_python.apache.main_server.server_admin

    except AttributeError:

        try:

            admin_email = mod_python.apache._server.server_admin

        except AttributeError:

            admin_email = ""

    try:

        httpcode = exc_value.httpcode

        req.status = httpcode

    except AttributeError:

        httpcode = None

        req.status = mod_python.apache.HTTP_INTERNAL_SERVER_ERROR

    try:

        publicmode = req.publicmode

    except AttributeError:

        publicmode = True

    try:

        login = req.user.login

    except AttributeError:

        login = None

    try:

        role = req.user.role

    except AttributeError:

        role = None

    # Log File

    try:

        for h in logging.getLogger().handlers:

            logging.getLogger().removeHandler(h)

        logging.basicConfig(level=logging.INFO,

            format='%(asctime)s %(levelname)s: ' +

                '(HTTP: ' + str(req.status) +

                ', Ref: ' + str(login) + '@' +

                str(socket.gethostname()) + str(req.uri) +

                ') %(message)s',

            filename=logfile,

            filemode='a')

    except IOError:

        logfail = True

    logging.debug('Logging Unhandled Exception')

    # A "bad" error message. We shouldn't get here unless IVLE

    # misbehaves (which is currently very easy, if things aren't set up

    # correctly).

    # Write the traceback.

    # If this is a non-4xx IVLEError, get the message and httpcode and

    # make the error message a bit nicer (but still include the

    # traceback).

    # We also need to special-case IVLEJailError, as we can get another

    # almost-exception out of it.

    codename, msg = None, None

    if exc_type is util.IVLEJailError:

        msg = exc_value.type_str + ": " + exc_value.message

        tb = 'Exception information extracted from IVLEJailError:\n'

        tb += urllib.unquote(exc_value.info)

    else:

        try:

            codename, msg = req.get_http_codename(httpcode)

        except AttributeError:

            pass

        # Override the default message with the supplied one,

        # if available.

        if hasattr(exc_value, 'message') and exc_value.message is not None:

            msg = exc_value.message

            # Prepend the exception type

            if exc_type != util.IVLEError:

                msg = exc_type.__name__ + ": " + repr(msg)

        tb = ''.join(traceback.format_exception(exc_type, exc_value,

                                                exc_traceback))

    # Logging

    logging.error('%s\n%s'%(str(msg), tb))

    # Error messages are only displayed is the user is NOT a student,

    # or if there has been a problem logging the error message

    show_errors = (not publicmode) and ((login and \

                        str(role) != "student") or logfail)

    req.write("""<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"                 

	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">                                      

<html xmlns="http://www.w3.org/1999/xhtml">

<head><title>IVLE Internal Server Error</title></head>

<body>

<h1>IVLE Internal Server Error""")

    if (show_errors):

        if (codename is not None

                    and httpcode != mod_python.apache.HTTP_INTERNAL_SERVER_ERROR):

            req.write(": %s" % cgi.escape(codename))

    req.write("""</h1>

<p>An error has occured which is the fault of the IVLE developers or

administration. The developers have been notified.</p>

""")

    if (show_errors):

        if msg is not None:

            req.write("<p>%s</p>\n" % cgi.escape(msg))

        if httpcode is not None:

            req.write("<p>(HTTP error code %d)</p>\n" % httpcode)

        req.write("""

<p>Please report this to <a href="mailto:%s">%s</a> (the system

administrator). Include the following information:</p>

""" % (cgi.escape(admin_email), cgi.escape(admin_email)))

        req.write("<pre>\n%s\n</pre>\n"%cgi.escape(tb))

        if logfail:

            req.write("<p>Warning: Could not open Error Log: '%s'</p>\n"

                %cgi.escape(logfile))

    req.write("</body></html>")