~azzar1/unity/add-show-desktop-key

# IVLE - Informatics Virtual Learning Environment

# 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

# Module: common.studpath

# Author: Matt Giuca

# Date:   14/12/2007

# Provides functions for translating URLs into physical locations in the

# student directories in the local file system.

# Also performs common authorization, disallowing students from visiting paths

# they dont own.

import os

import pysvn

import conf

from common import util

# Make a Subversion client object (for published)

svnclient = pysvn.Client()

def url_to_local(urlpath):

    """Given a URL path (part of a URL query string, see below), returns a

    tuple of

        * the username of the student whose directory is being browsed

        * the absolute path in the file system where that file will be

            found within the student directories.

    urlpath: Part of the URL, but only the part *after* the application. For

    instance, given the URL "/ivle/browse/joe/home/mydir/myfile", urlpath will

    be just "joe/home/mydir/myfile". The expected result is something like

    ("joe", "/home/informatics/jails/joe/home/joe/home/mydir/myfile").

    Note that the actual location is not guaranteed by this interface (this

    function serves as a single point of control as to how URLs map onto

    student directories).

    Returns (None, None) if the path is empty.

    See also: conf.jail_base

    """

    # First normalise the path

    urlpath = os.path.normpath(urlpath)

    # Now if it begins with ".." or separator, then it's illegal

    if urlpath.startswith("..") or urlpath.startswith(os.sep):

        return (None, None)

    # Note: User can be a group name. There is absolutely no difference in our

    # current directory scheme.

    (user, subpath) = util.split_path(urlpath)

    if user is None: return (None, None)

    # Join the user onto 'home' then the full path specified.

    # This results in the user's name being repeated twice, which is in

    # accordance with our directory scheme.

    # (The first time is the name of the jail, the second is the user's home

    # directory within the jail).

    path = os.path.join(conf.jail_base, user, 'home', urlpath)

    return (user, path)

def url_to_jailpaths(urlpath):

    """Given a URL path (part of a URL query string), returns a tuple of

        * the username of the student whose directory is being browsed

        * the absolute path where the jail will be located.

        * the path of the file relative to the jail.

    urlpath: See urlpath in url_to_local.

    >>> url_to_jailpaths("joe/home/mydir/myfile")

    ("joe", "/home/informatics/jails/joe", "home/joe/home/mydir/myfile")

    >>> url_to_jailpaths("")

    (None, None, None)

    """

    # First normalise the path

    urlpath = os.path.normpath(urlpath)

    # Now if it begins with ".." then it's illegal

    if urlpath.startswith(".."):

        return (None, None, None)

    # Note: User can be a group name. There is absolutely no difference in our

    # current directory scheme.

    (user, subpath) = util.split_path(urlpath)

    if user is None: return (None, None, None)

    jail = os.path.join(conf.jail_base, user)

    path = os.path.join('home', urlpath)

    return (user, jail, path)

def published(path):

    """Given a path on the LOCAL file system, determines whether the path has

    its "ivle:published" property active (in subversion). Returns True

    or False."""

    # Read SVN properties for this path

    try:

        props = svnclient.propget("ivle:published", path, recurse=False)

    except pysvn.ClientError:

        # Not under version control? Then it isn't published.

        return False

    return len(props) > 0

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.

    This is for general authorization (assuming not in public mode; this is

    the standard auth code for fileservice, download and serve).

    """

    # TODO: Groups

    # First normalise the path

    urlpath = os.path.normpath(req.path)

    # Now if it begins with ".." or separator, then it's illegal

    if urlpath.startswith("..") or urlpath.startswith(os.sep):

        req.throw_error(req.HTTP_FORBIDDEN)

    (owner, _) = util.split_path(urlpath)

    if req.username != owner:

        req.throw_error(req.HTTP_FORBIDDEN)

def authorize_public(req):

    """A different kind of authorization. Rather than making sure the

    logged-in user owns the file, this checks if the file is in a published

    directory.

    This is for the "public mode" of the serve app.

    Same interface as "authorize" - None on success, HTTP_FORBIDDEN exception

    raised on failure.

    """

    _, path = url_to_local(req.path)

    dirpath, _ = os.path.split(path)

    if not published(dirpath):

        req.throw_error(req.HTTP_FORBIDDEN)