~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: server

# Author: Tom Conway, Matt Giuca

# Date: 13/12/2007

# Serves content to the user (acting as a web server for students files).

# For most file types we just serve the static file, but

# for python files, we evaluate the python script inside

# our safe execution environment.

from common import (util, studpath, interpret)

import conf

import conf.app.server

import os

import mimetypes

def handle(req):

    """Handler for the Server application which serves pages."""

    req.write_html_head_foot = False

    # Get the username of the student whose work we are browsing, and the path

    # on the local machine where the file is stored.

    (user, path) = studpath.url_to_local(req.path)

    if user is None:

        # TODO: Nicer 404 message?

        req.throw_error(req.HTTP_NOT_FOUND)

    serve_file(req, user, path)

def authorize(req):

    """Given a request, checks whether req.username is allowed to

    access req.path. Returns None on authorization success. Raises

    HTTP_FORBIDDEN on failure.

    """

    if req.publicmode:

        # Public mode authorization: any user can access any other user's

        # files, BUT the accessed file needs to have its "ivle:published" flag

        # turned on in the SVN status.

        studpath.authorize_public(req)

    else:

        # Private mode authorization: standard (only logged in user can access

        # their own files, and can access all of them).

        studpath.authorize(req)

def serve_file(req, owner, filename):

    """Serves a file, using one of three possibilities: interpreting the file,

    serving it directly, or denying it and returning a 403 Forbidden error.

    No return value. Writes to req (possibly throwing a server error exception

    using req.throw_error).

    req: An IVLE request object.

    owner: Username of the user who owns the file being served.

    filename: Filename in the local file system.

    """

    # Authorize access. If failure, this throws a HTTP_FORBIDDEN error.

    authorize(req)

    # First get the mime type of this file

    # (Note that importing common.util has already initialised mime types)

    (type, _) = mimetypes.guess_type(filename)

    if type is None:

        type = conf.mimetypes.default_mimetype

    # If this type is to be interpreted

    if os.path.isdir(filename):

        # 403 Forbidden error for visiting a directory

        # (Not giving a directory listing, since this can be seen by

        # the world at large. Directory contents are private).

        req.throw_error(req.HTTP_FORBIDDEN)

    elif type in conf.app.server.interpreters:

        interp_name = conf.app.server.interpreters[type]

        try:

            # Get the interpreter function object

            interp_object = interpret.interpreter_objects[interp_name]

        except KeyError:

            # TODO: Nicer 500 message (this is due to bad configuration in

            # conf/app/server.py)

            req.throw_error(req.HTTP_INTERNAL_SERVER_ERROR)

        interpret.interpret_file(req, owner, filename, interp_object)

    else:

        # Otherwise, use the blacklist/whitelist to see if this file should be

        # served or disallowed

        if conf.app.server.blacklist_served_filetypes:

            toserve = type not in conf.app.server.served_filetypes_blacklist

        else:

            toserve = type in conf.app.server.served_filetypes_whitelist

        # toserve or not toserve

        if not toserve:

            # TODO: Nicer 403 message

            req.throw_error(req.HTTP_FORBIDDEN)

        else:

            serve_file_direct(req, filename, type)

def serve_file_direct(req, filename, type):

    """Serves a file by directly writing it out to the response.

    req: An IVLE request object.

    filename: Filename in the local file system.

    type: String. Mime type to serve the file with.

    """

    if not os.access(filename, os.R_OK):

        req.throw_error(req.HTTP_NOT_FOUND)

    req.content_type = type

    req.sendfile(filename)