Apache-AuthCookie
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lib/Apache/AuthCookie.pm view on Meta::CPAN
</Location>
# These documents don't require logging in, but allow it.
<FilesMatch "\.ok$">
AuthType Sample::Apache::AuthCookieHandler
AuthName WhatEver
PerlFixupHandler Sample::Apache::AuthCookieHandler->recognize_user
</FilesMatch>
# This is the action of the login.pl script above.
<Files LOGIN>
AuthType Sample::Apache::AuthCookieHandler
AuthName WhatEver
SetHandler perl-script
PerlHandler Sample::Apache::AuthCookieHandler->login
</Files>
=head1 DESCRIPTION
B<Apache::AuthCookie> allows you to intercept a user's first
unauthenticated access to a protected document. The user will be
presented with a custom form where they can enter authentication
credentials. The credentials are posted to the server where AuthCookie
verifies them and returns a session key.
The session key is returned to the user's browser as a cookie. As a
cookie, the browser will pass the session key on every subsequent
accesses. AuthCookie will verify the session key and re-authenticate
the user.
All you have to do is write a custom module that inherits from
AuthCookie. Your module is a class which implements two methods:
=over 4
=item C<authen_cred()>
Verify the user-supplied credentials and return a session key. The
session key can be any string - often you'll use some string
containing username, timeout info, and any other information you need
to determine access to documents, and append a one-way hash of those
values together with some secret key.
=item C<authen_ses_key()>
Verify the session key (previously generated by C<authen_cred()>,
possibly during a previous request) and return the user ID. This user
ID will be fed to C<$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>.
=item 5.
You can optionally specify the name of your cookie using the C<CookieName>
directive. For instance, if your AuthName is C<WhatEver>, you can put the
command
PerlSetVar WhatEverCookieName MyCustomName
into your server setup file and your cookies for this AuthCookie realm will be
named MyCustomName. Default is AuthType_AuthName.
=item 6.
By default users must satisfy ALL of the C<require> directives. If you
want authentication to succeed if ANY C<require> directives are met, use the
C<Satisfy> directive. For instance, if your AuthName is C<WhatEver>, you can
put the command
PerlSetVar WhatEverSatisfy Any
into your server startup file and authentication for this realm will succeed if
ANY of the C<require> directives are met.
=back
This is the flow of the authentication handler, less the details of the
redirects. Two REDIRECT's are used to keep the client from displaying
the user's credentials in the Location field. They don't really change
AuthCookie's model, but they do add another round-trip request to the
client.
(-----------------------) +---------------------------------+
( Request a protected ) | AuthCookie sets custom error |
( page, but user hasn't )---->| document and returns |
( authenticated (no ) | FORBIDDEN. Apache abandons |
( session key cookie) ) | current request and creates sub |
(-----------------------) | request for the error document. |<-+
| Error document is a script that | |
| generates a form where the user | |
return | enters authentication | |
^------------------->| credentials (login & password). | |
/ \ False +---------------------------------+ |
/ \ | |
/ \ | |
/ \ V |
/ \ +---------------------------------+ |
/ Pass \ | User's client submits this form | |
/ user's \ | to the LOGIN URL, which calls | |
| credentials |<------------| AuthCookie->login(). | |
\ to / +---------------------------------+ |
\authen_cred/ |
\ function/ |
\ / |
\ / |
\ / +------------------------------------+ |
\ / return | Authen cred returns a session | +--+
V------------->| key which is opaque to AuthCookie.*| |
True +------------------------------------+ |
| |
+--------------------+ | +---------------+
| | | | If we had a |
V | V | cookie, add |
+----------------------------+ r | ^ | a Set-Cookie |
| If we didn't have a session| e |T / \ | header to |
| key cookie, add a | t |r / \ | override the |
| Set-Cookie header with this| u |u / \ | invalid cookie|
| session key. Client then | r |e / \ +---------------+
| returns session key with | n | / pass \ ^
| successive requests | | / session \ |
+----------------------------+ | / key to \ return |
| +-| authen_ses_key|------------+
V \ / False
+-----------------------------------+ \ /
| Tell Apache to set Expires header,| \ /
| set user to user ID returned by | \ /
| authen_ses_key, set authentication| \ /
| to our type (e.g. AuthCookie). | \ /
+-----------------------------------+ \ /
V
(---------------------) ^
( Request a protected ) |
( page, user has a )--------------+
( session key cookie )
(---------------------)
* The session key that the client gets can be anything you want. For
example, encrypted information about the user, a hash of the
username and password (similar in function to Digest
authentication), or the user name and password in plain text
(similar in function to HTTP Basic authentication).
The only requirement is that the authen_ses_key function that you
create must be able to determine if this session_key is valid and
map it back to the originally authenticated user ID.
=head1 METHODS
=head2 authen_cred($r, @credentials)
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 ($$\@) {
my $self = shift; # Package name (same as AuthName directive)
my $r = shift; # Apache request object
my @cred = @_; # Credentials from login form
...blah blah blah, create a session key...
return $session_key;
}
The only limitation on the session key is that you should be able to
look at it later and determine the user's username. You are
responsible for implementing your own session key format. A typical
format is to make a string that contains the username, an expiration
time, whatever else you need, and an MD5 hash of all that data
together with a secret key. The hash will ensure that the user
doesn't tamper with the session key. More info in the Eagle book.
=head2 authen_ses_key($r, $session_key)
You must define this method yourself in your subclass of
Apache::AuthCookie. Its job is to look at a session key and determine
whether it is valid. If so, it returns the username of the
authenticated user.
sub authen_ses_key ($$$) {
my ($self, $r, $session_key) = @_;
...blah blah blah, check whether $session_key is valid...
return $ok ? $username : undef;
}
Optionally, return an array of 2 or more items that will be passed to method
custom_errors. It is the responsibility of this method to return the correct
response to the main Apache module.
=head2 custom_errors($r,@_)
Note: this interface is experimental.
This method handles the server response when you wish to access the Apache
custom_response method. Any suitable response can be used. this is
particularly useful when implementing 'by directory' access control using
the user authentication information. i.e.
/restricted
/one user is allowed access here
/two not here
lib/Apache/AuthCookie.pm view on Meta::CPAN
The Cookie name
=item *
value
the Cookie value
=item *
expires (optional)
When the cookie expires. See L<Apache::AuthCookie::Util/expires()>. Uses C<${auth_name}Expires> if not given.
=back
All other cookie settings come from C<PerlSetVar> settings.
=head2 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.
=head2 get_cookie_path(): string
Returns the value of C<PerlSetVar ${auth_name}Path>.
=head1 EXAMPLE
For an example of how to use Apache::AuthCookie, you may want to check
out the test suite, which runs AuthCookie through a few of its paces.
The documents are located in t/eg/, and you may want to peruse
t/real.t to see the generated httpd.conf file (at the bottom of
real.t) and check out what requests it's making of the server (at the
top of real.t).
=head1 THE LOGIN SCRIPT
You will need to create a login script (called login.pl above) that
generates an HTML form for the user to fill out. You might generate
the page using an Apache::Registry script, or an HTML::Mason
component, or perhaps even using a static HTML page. It's usually
useful to generate it dynamically so that you can define the
'destination' field correctly (see below).
The following fields must be present in the form:
=over 4
=item 1.
The ACTION of the form must be /LOGIN (or whatever you defined in your
server configuration as handled by the ->login() method - see example
in the SYNOPSIS section).
=item 2.
The various user input fields (username, passwords, etc.) must be
named 'credential_0', 'credential_1', etc. on the form. These will
get passed to your authen_cred() method.
=item 3.
You must define a form field called 'destination' that tells
AuthCookie where to redirect the request after successfully logging
in. Typically this value is obtained from C<$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 why
the user is being asked to log in. In other words, if the user sent
bad credentials, then it might be useful to display an error message
saying that the given username or password are invalid. Also, it
might be useful to determine the difference between a user that sent
an invalid auth cookie, and a user that sent no auth cookie at all. To
cope with these situations, B<AuthCookie> will set
C<$r-E<gt>subprocess_env('AuthCookieReason')> to one of the following values.
=over 4
=item I<no_cookie>
The user presented no cookie at all. Typically this means the user is
trying to log in for the first time.
=item I<bad_cookie>
The cookie the user presented is invalid. Typically this means that the user
is not allowed access to the given page.
=item I<bad_credentials>
The user tried to log in, but the credentials that were passed are invalid.
=back
You can examine this value in your login form by examining
C<$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<$r-E<gt>subprocess_env>.
=head1 THE LOGOUT SCRIPT
If you want to let users log themselves out (something that can't be
done using Basic Auth), you need to create a logout script. For an
example, see t/htdocs/docs/logout.pl. Logout scripts may want to take
advantage of AuthCookie's C<logout()> method, which will set the
proper cookie headers in order to clear the user's cookie. This
usually looks like C<$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 ENCODING AND CHARACTER SETS
=head2 Encoding
AuthCookie provides support for decoding POST/GET data if you tell it what the
client encoding is. You do this by setting the C<< ${auth_name}Encoding >>
setting in C<httpd.conf>. E.g.:
PerlSetVar WhateEverEncoding UTF-8
# and you also need to arrange for charset=UTF-8 at the end of the
# Content-Type header with something like:
AddDefaultCharset UTF-8
Note that you B<can> use charsets other than C<UTF-8>, however, you need to
arrange for the browser to send the right encoding back to the server.
lib/Apache/AuthCookie.pm view on Meta::CPAN
=item *
The value stored in C<< $r-E<gt>connection-E<gt>user >> will be encoded as
B<bytes>, not characters using the configured encoding name. This is because
the value stored by mod_perl is a C API string, and not a perl string. You can
use L</decoded_user()> to get user string encoded using B<character> semantics.
=back
This does has some caveats:
=over 4
=item *
your L</authen_cred()> and L</authen_ses_key()> function is expected to return
a decoded username, either by passing it through L<Encode/decode()>, or, by
turning on the UTF8 flag if appropriate.
=item *
Due to the way HTTP works, cookies cannot contain non-ASCII characters.
Because of this, if you are including the username in your generated session
key, you will need to escape any non-ascii characters in the session key
returned by L</authen_cred()>.
=item *
Similarly, you must reverse this escaping process in L</authen_ses_key()> and
return a L<Encode/decode()> decoded username. If your L</authen_cred()>
function already only generates ASCII-only session keys then you do not need to
worry about any of this.
=item *
The value stored in C<< $r-E<gt>connection-E<gt>user >> will be encoded using
bytes semantics using the configured B<Encoding>. If you want the decoded user
value, use L</decoded_user()> instead.
=back
=head2 Requires
You can also specify what the charset is of the Apache C<< $r-E<gt>requires >>
data is by setting C<< ${auth_name}RequiresEncoding >> in httpd.conf.
E.g.:
PerlSetVar WhatEverRequiresEncoding UTF-8
This will make it so that AuthCookie will decode your C<requires> directives
using the configured character set. You really only need to do this if you
have used non-ascii characters in any of your C<requires> directives in
httpd.conf. e.g.:
requires user programmør
=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.
=head2 TO DO
=over 4
=item *
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 HISTORY
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)>.
=head1 SOURCE
The development version is on github at L<https://github.com/mschout/apache-authcookie>
and may be cloned from L<https://github.com/mschout/apache-authcookie.git>
=head1 BUGS
Please report any bugs or feature requests on the bugtracker website
L<https://github.com/mschout/apache-authcookie/issues>
When submitting a bug or request, please include a test-file or a
patch to an existing test-file that illustrates the bug or desired
feature.
=head1 AUTHOR
Michael Schout <mschout@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2000 by Ken Williams.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut
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