view release on metacpan or  search on metacpan

AuthCookie.pm  view on Meta::CPAN

Apache::AuthCookie - Perl Authentication and Authorization via cookies

=head1 SYNOPSIS

Make sure your mod_perl is at least 1.24, with StackedHandlers,
MethodHandlers, Authen, and Authz compiled in.

 # In httpd.conf or .htaccess:
 PerlModule Sample::AuthCookieHandler
 PerlSetVar WhatEverPath /
 PerlSetVar WhatEverLoginScript /login.pl
 
 # The following line is optional - it allows you to set the domain
 # scope of your cookie.  Default is the current domain.
 PerlSetVar WhatEverDomain .yourdomain.com

 # Use this to only send over a secure connection
 PerlSetVar WhatEverSecure 1

 # Usually documents are uncached - turn off here
 PerlSetVar WhatEverCache 1

 # Use this to make your cookies persistent (+2 hours here)
 PerlSetVar WhatEverExpires +2h

 # These documents require user to be logged in.
 <Location /protected>
  AuthType Sample::AuthCookieHandler
  AuthName WhatEver
  PerlAuthenHandler Sample::AuthCookieHandler->authenticate
  PerlAuthzHandler Sample::AuthCookieHandler->authorize
  require valid-user
 </Location>

 # These documents don't require logging in, but allow it.
 <FilesMatch "\.ok$">
  AuthType Sample::AuthCookieHandler
  AuthName WhatEver
  PerlFixupHandler Sample::AuthCookieHandler->recognize_user
 </FilesMatch>

 # This is the action of the login.pl script above.
 <Files LOGIN>
  AuthType Sample::AuthCookieHandler
  AuthName WhatEver
  SetHandler perl-script
  PerlHandler Sample::AuthCookieHandler->login
 </Files>

=head1 DESCRIPTION

B<Apache::AuthCookie> allows you to intercept a user's first
unauthenticated access to a protected document. The user will be
presented with a custom form where they can enter authentication
credentials. The credentials are posted to the server where AuthCookie
verifies them and returns a session key.

The session key is returned to the user's browser as a cookie. As a
cookie, the browser will pass the session key on every subsequent
accesses. AuthCookie will verify the session key and re-authenticate
the user.

All you have to do is write a custom module that inherits from
AuthCookie.  Your module is a class which implements two methods:

=over 4

=item C<authen_cred()>

Verify the user-supplied credentials and return a session key.  The
session key can be any string - often you'll use some string
containing username, timeout info, and any other information you need
to determine access to documents, and append a one-way hash of those
values together with some secret key.

=item C<authen_ses_key()>

Verify the session key (previously generated by C<authen_cred()>,
possibly during a previous request) and return the user ID.  This user
ID will be fed to C<$r-E<gt>connection-E<gt>user()> to set Apache's
idea of who's logged in.

=back

By using AuthCookie versus Apache's built-in AuthBasic you can design
your own authentication system.  There are several benefits.

=over 4

=item 1.

The client doesn't *have* to pass the user credentials on every
subsequent access.  If you're using passwords, this means that the
password can be sent on the first request only, and subsequent
requests don't need to send this (potentially sensitive) information.
This is known as "ticket-based" authentication.

=item 2.

When you determine that the client should stop using the
credentials/session key, the server can tell the client to delete the
cookie.  Letting users "log out" is a notoriously impossible-to-solve
problem of AuthBasic.

=item 3.

AuthBasic dialog boxes are ugly.  You can design your own HTML login
forms when you use AuthCookie.

=item 4.

You can specify the domain of a cookie using PerlSetVar commands.  For
instance, if your AuthName is C<WhatEver>, you can put the command 

 PerlSetVar WhatEverDomain .yourhost.com

into your server setup file and your access cookies will span all
hosts ending in C<.yourhost.com>.

=back

AuthCookie.pm  view on Meta::CPAN

useful to generate it dynamically so that you can define the
'destination' field correctly (see below).

The following fields must be present in the form:

=over 4

=item 1.

The ACTION of the form must be /LOGIN (or whatever you defined in your
server configuration as handled by the ->login() method - see example
in the SYNOPSIS section).

=item 2.

The various user input fields (username, passwords, etc.) must be
named 'credential_0', 'credential_1', etc. on the form.  These will
get passed to your authen_cred() method.

=item 3.

You must define a form field called 'destination' that tells
AuthCookie where to redirect the request after successfully logging
in.  Typically this value is obtained from C<$r-E<gt>prev-E<gt>uri>.
See the login.pl script in t/eg/.

=back

In addition, you might want your login page to be able to tell the
difference between a user that sent an incorrect auth cookie, and a
user that sent no auth cookie at all.  These typically correspond,
respectively, to users who logged in incorrectly or aren't allowed to
access the given page, and users who are trying to log in for the
first time.  To help you differentiate between the two, B<AuthCookie>
will set C<$r-E<gt>subprocess_env('AuthCookieReason')> to either
C<bad_cookie> or C<no_cookie>.  You can examine this value in your
login form by examining
C<$r-E<gt>prev-E<gt>subprocess_env('AuthCookieReason')> (because it's
a sub-request).

Of course, if you want to give more specific information about why
access failed when a cookie is present, your C<authen_ses_key()>
method can set arbitrary entries in C<$r-E<gt>subprocess_env>.

=head1 THE LOGOUT SCRIPT

If you want to let users log themselves out (something that can't be
done using Basic Auth), you need to create a logout script.  For an
example, see t/eg/logout.pl.  Logout scripts may want to take
advantage of AuthCookie's C<logout()> method, which will set the
proper cookie headers in order to clear the user's cookie.  This
usually looks like C<$r-E<gt>auth_type-E<gt>logout($r);>.

Note that if you don't necessarily trust your users, you can't count
on cookie deletion for logging out.  You'll have to expire some
server-side login information too.  AuthCookie doesn't do this for
you, you have to handle it yourself.

=head1 ABOUT SESSION KEYS

Unlike the sample AuthCookieHandler, you have you verify the user's
login and password in C<authen_cred()>, then you do something
like:

    my $date = localtime;
    my $ses_key = MD5->hexhash(join(';', $date, $PID, $PAC));

save C<$ses_key> along with the user's login, and return C<$ses_key>.

Now C<authen_ses_key()> looks up the C<$ses_key> passed to it and
returns the saved login.  I use Oracle to store the session key and
retrieve it later, see the ToDo section below for some other ideas.

=head1 KNOWN LIMITATIONS

If the first unauthenticated request is a POST, it will be changed to
a GET after the user fills out the login forms, and POSTed data will
be lost.

=head2 TO DO

=over 4

=item *

There ought to be a way to solve the POST problem in the LIMITATIONS
section.  It involves being able to re-insert the POSTed content into
the request stream after the user authenticates.

It might be nice if the logout method could accept some parameters
that could make it easy to redirect the user to another URI, or
whatever.  I'd have to think about the options needed before I
implement anything, though.

=back

=head1 CVS REVISION

$Id: AuthCookie.pm,v 2.16 2001/06/01 15:50:27 mschout Exp $

=head1 AUTHOR

Michael Schout <mschout@gkg.net>

Originally written by Eric Bartley <bartley@purdue.edu>

versions 2.x were written by Ken Williams <ken@forum.swarthmore.edu>

=head1 SEE ALSO

L<perl(1)>, L<mod_perl(1)>, L<Apache(1)>.

=cut