~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: dispatch.login

# Author: Matt Giuca

# Date: 21/12/2007

# Provides services for checking logins and presenting the login page.

from mod_python import (util, Session)

from auth import authenticate

def login(req):

    """Determines whether the user is logged in or not (looking at sessions),

    and if not, presents the login page. Returns a String username, or None

    if not logged in.

    If the user was already logged in, nothing is written to req. Returns

    a string of the username.

    If the user was not logged in, but manages to authenticate due to

    included postdata with a valid username/password, throws a redirect

    back to the same page (to avoid leaving POSTDATA in the browser).

    If the user is not logged in, or fails to authenticate, a full page is

    written to req. Returns None. The caller should immediately terminate.

    """

    session = req.get_session()

    # Check the session to see if someone is logged in. If so, go with it.

    # No security is required here. You must have already been authenticated

    # in order to get a 'login_name' variable in the session.

    try:

        return session['login_name']

    except KeyError:

        pass

    badlogin = False

    # Check if there is any postdata containing login information

    if req.method == 'POST':

        fields = req.get_fieldstorage()

        username = fields.getfirst('user')

        password = fields.getfirst('pass')

        if username is not None:

            # From this point onwards, we will be showing an error message

            # if unsuccessful.

            # Authenticate

            if (password is not None and

                authenticate.authenticate(username.value, password.value)):

                # Success - Set the session and redirect to avoid POSTDATA

                session['login_name'] = username.value

                session.save()

                req.throw_redirect(req.uri)

            else:

                badlogin = True

    # User is not logged in. Present the login box.

    # Give a 403 Forbidden status, but present a full HTML login page

    # instead of the usual 403 error.

    req.status = req.HTTP_FORBIDDEN

    req.content_type = "text/html"

    req.title = "Login"

    req.write_html_head_foot = True

    # Write the HTML for the login page

    # If badlogin, display an error message indicating a failed login

    if badlogin:

        req.write("""<p class="error">Invalid username or password.</p>""")

    req.write("""<form action="" method="post">

  <table>

    <tr><td>Username:</td><td><input name="user" type="text" /></td></tr>

    <tr><td>Password:</td><td><input name="pass" type="password" /></td></tr>

    <tr><td colspan="2"><input type="submit" value="Login" /></td></tr>

  </table>

</form>

""")

    return None

def get_username(req):

    """Gets the name of the logged in user, without presenting a login box

    or attempting to authenticate.

    Returns None if there is no user logged in.

    """

    session = req.get_session()

    # Check the session to see if someone is logged in. If so, go with it.

    # No security is required here. You must have already been authenticated

    # in order to get a 'login_name' variable in the session.

    try:

        return session['login_name']

    except KeyError:

        return None