view release on metacpan or  search on metacpan

AuthCookie.pm  view on Meta::CPAN

any Apache docs on the matter.  If you need one behavior or the other,
be careful.  I may change it if I discover that ANY is correct.

=item * authen_cred()

You must define this method yourself in your subclass of
C<Apache::AuthCookie>.  Its job is to create the session key that will
be preserved in the user's cookie.  The arguments passed to it are:

 sub authen_cred ($$\@) {
   my $self = shift;  # Package name (same as AuthName directive)
   my $r    = shift;  # Apache request object
   my @cred = @_;     # Credentials from login form

   ...blah blah blah, create a session key...
   return $session_key;
 }

The only limitation on the session key is that you should be able to
look at it later and determine the user's username.  You are
responsible for implementing your own session key format.  A typical
format is to make a string that contains the username, an expiration
time, whatever else you need, and an MD5 hash of all that data
together with a secret key.  The hash will ensure that the user
doesn't tamper with the session key.  More info in the Eagle book.

=item * authen_ses_key()

You must define this method yourself in your subclass of
Apache::AuthCookie.  Its job is to look at a session key and determine
whether it is valid.  If so, it returns the username of the
authenticated user.

 sub authen_ses_key ($$$) {
   my ($self, $r, $session_key) = @_;
   ...blah blah blah, check whether $session_key is valid...
   return $ok ? $username : undef;
 }

=item * login()

This method handles the submission of the login form.  It will call
the C<authen_cred()> method, passing it C<$r> and all the submitted
data with names like C<"credential_#">, where # is a number.  These will
be passed in a simple array, so the prototype is
C<$self-E<gt>authen_cred($r, @credentials)>.  After calling
C<authen_cred()>, we set the user's cookie and redirect to the
URL contained in the C<"destination"> submitted form field.

=item * login_form()

This method is responsible for displaying the login form. The default
implementation will make an internal redirect and display the URL you
specified with the C<PerlSetVar WhatEverLoginForm> configuration
directive. You can overwrite this method to provide your own
mechanism.

=item * logout()

This is simply a convenience method that unsets the session key for
you.  You can call it in your logout scripts.  Usually this looks like
C<$r-E<gt>auth_type-E<gt>logout($r);>.

=item * send_cookie($session_key)

By default this method simply sends out the session key you give it.
If you need to change the default behavior (perhaps to update a
timestamp in the key) you can override this method.

=item * recognize_user()

If the user has provided a valid session key but the document isn't
protected, this method will set C<$r-E<gt>connection-E<gt>user>
anyway.  Use it as a PerlFixupHandler, unless you have a better idea.

=item * key()

This method will return the current session key, if any.  This can be
handy inside a method that implements a C<require> directive check
(like the C<species> method discussed above) if you put any extra
information like clearances or whatever into the session key.

=back

=head1 UPGRADING FROM VERSION 1.4

There are a few interface changes that you need to be aware of
when migrating from version 1.x to 2.x.  First, the authen() and
authz() methods are now deprecated, replaced by the new authenticate()
and authorize() methods.  The old methods will go away in a couple
versions, but are maintained intact in this version to ease the task
of upgrading.  The use of these methods is essentially the same, though.

Second, when you change to the new method names (see previous
paragraph), you must change the action of your login forms to the
location /LOGIN (or whatever URL will call your module's login()
method).  You may also want to change their METHOD to POST instead of
GET, since that's much safer and nicer to look at (but you can leave
it as GET if you bloody well want to, for some god-unknown reason).

Third, you must change your login forms (see L<THE LOGIN SCRIPT>
below) to indicate how requests should be redirected after a
successful login.

Fourth, you might want to take advantage of the new C<logout()>
method, though you certainly don't have to.

=head1 EXAMPLE

For an example of how to use Apache::AuthCookie, you may want to check
out the test suite, which runs AuthCookie through a few of its paces.
The documents are located in t/eg/, and you may want to peruse
t/real.t to see the generated httpd.conf file (at the bottom of
real.t) and check out what requests it's making of the server (at the
top of real.t).

=head1 THE LOGIN SCRIPT

You will need to create a login script (called login.pl above) that
generates an HTML form for the user to fill out.  You might generate
the page using an Apache::Registry script, or an HTML::Mason
component, or perhaps even using a static HTML page.  It's usually
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