~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 inspect

import mod_python

import routes

from ivle import util

import ivle.conf

import ivle.conf.apps

from ivle.dispatch.request import Request

from ivle.dispatch import login

from ivle.webapp.base.plugins import ViewPlugin

from ivle.webapp.errors import HTTPError

import apps

import html

# XXX List of plugins, which will eventually be read in from conf

plugins_HACK = [

    'ivle.webapp.core#Plugin',

    'ivle.webapp.admin.user#Plugin',

    'ivle.webapp.tutorial#Plugin',

    'ivle.webapp.admin.subject#Plugin',

    'ivle.webapp.filesystem.browser#Plugin',

    'ivle.webapp.filesystem.diff#Plugin',

    'ivle.webapp.filesystem.svnlog#Plugin',

    'ivle.webapp.groups#Plugin',

    'ivle.webapp.console#Plugin',

    'ivle.webapp.security#Plugin',

    'ivle.webapp.media#Plugin',

    'ivle.webapp.forum#Plugin',

] 

def generate_route_mapper(view_plugins):

    """

    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 plugin.urls:

            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 get_plugin(pluginstr):

    plugin_path, classname = pluginstr.split('#')

    # Load the plugin module from somewhere in the Python path

    # (Note that plugin_path is a fully-qualified Python module name).

    return (plugin_path,

            getattr(__import__(plugin_path, fromlist=[classname]), classname))

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, html.write_html_head)

    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:

        req.user = login.get_user_details(req)

    ### BEGIN New plugins framework ###

    # XXX This should be done ONCE per Python process, not per request.

    # (Wait till WSGI)

    # XXX No authentication is done here

    req.plugins = dict([get_plugin(pluginstr) for pluginstr in plugins_HACK])

    # Index the plugins by base class

    req.plugin_index = {}

    for plugin in req.plugins.values():

        # Getmro returns a tuple of all the super-classes of the plugin

        for base in inspect.getmro(plugin):

            if base not in req.plugin_index:

                req.plugin_index[base] = []

            req.plugin_index[base].append(plugin)

    req.reverse_plugins = dict([(v, k) for (k, v) in req.plugins.items()])

    req.mapper = generate_route_mapper(req.plugin_index[ViewPlugin])

    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)

            # 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

            else:

                req.write(e.message)

                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

    ### END New plugins framework ###

    # Check req.app to see if it is valid. 404 if not.

    if req.app is not None and req.app not in ivle.conf.apps.app_url:

        req.throw_error(Request.HTTP_NOT_FOUND,

            "There is no application called %s." % repr(req.app))

    # Special handling for public mode - only allow the public app, call it

    # and get out.

    # NOTE: This will not behave correctly if the public app uses

    # write_html_head_foot, but "serve" does not.

    if req.publicmode:

        if req.app != ivle.conf.apps.public_app:

            req.throw_error(Request.HTTP_FORBIDDEN,

                "This application is not available on the public site.")

        app = ivle.conf.apps.app_url[ivle.conf.apps.public_app]

        apps.call_app(app.dir, req)

        return req.OK

    # app is the App object for the chosen app

    if req.app is None:

        app = ivle.conf.apps.app_url[ivle.conf.apps.default_app]

    else:

        app = ivle.conf.apps.app_url[req.app]

    # Check if app requires auth. If so, perform authentication and login.

    # This will either return a User object, None, or perform a redirect

    # which we will not catch here.

    if app.requireauth:

        req.user = login.login(req)

        logged_in = req.user is not None

    else:

        req.user = login.get_user_details(req)

        logged_in = True

    if logged_in:

        # Keep the user's session alive by writing to the session object.

        # req.get_session().save()

        # Well, it's a fine idea, but it creates considerable grief in the

        # concurrent update department, so instead, we'll just make the

        # sessions not time out.

        req.get_session().unlock()

        # If user did not specify an app, HTTP redirect to default app and

        # exit.

        if req.app is None:

            req.throw_redirect(util.make_path(ivle.conf.apps.default_app))

        # Set the default title to the app's tab name, if any. Otherwise URL

        # name.

        if app.name is not None:

            req.title = app.name

        else:

            req.title = req.app

        # Call the specified app with the request object

        apps.call_app(app.dir, req)

    # if not logged in, login.login will have written the login box.

    # Just clean up and exit.

    # MAKE SURE we write the HTTP (and possibly HTML) header. This

    # wouldn't happen if nothing else ever got written, so we have to make

    # sure.

    req.ensure_headers_written()

    # When done, write out the HTML footer if the app has requested it

    if req.write_html_head_foot:

        html.write_html_foot(req)

    # Note: Apache will not write custom HTML error messages here.

    # Use req.throw_error to do that.

    return req.OK

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.

    IVLE reqs may have the HTML head/foot written (on a 400 error), but

    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')

    # We handle 3 types of error.

    # IVLEErrors with 4xx response codes (client error).

    # IVLEErrors with 5xx response codes (handled server error).

    # Other exceptions (unhandled server error).

    # IVLEErrors should not have other response codes than 4xx or 5xx

    # (eg. throw_redirect should have been used for 3xx codes).

    # Therefore, that is treated as an unhandled error.

    if (exc_type == util.IVLEError and httpcode >= 400

        and httpcode <= 499):

        # IVLEErrors with 4xx response codes are client errors.

        # Therefore, these have a "nice" response (we even coat it in the IVLE

        # HTML wrappers).

        req.write_html_head_foot = True

        req.write_javascript_settings = False

        req.write('<div id="ivle_padding">\n')

        try:

            codename, msg = req.get_http_codename(httpcode)

        except AttributeError:

            codename, msg = None, None

        # Override the default message with the supplied one,

        # if available.

        if exc_value.message is not None:

            msg = exc_value.message

        if codename is not None:

            req.write("<h1>Error: %s</h1>\n" % cgi.escape(codename))

        else:

            req.write("<h1>Error</h1>\n")

        if msg is not None:

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

        else:

            req.write("<p>An unknown error occured.</p>\n")

        # Logging

        logging.info(str(msg))

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

        if logfail:

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

                %cgi.escape(logfile))

        req.write('</div>\n')

        html.write_html_foot(req)

    else:

        # 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__ + ": " + 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>")