Provided by: libapache2-authcookie-perl_3.20-1_all 
NAME
Apache::AuthCookie - Perl Authentication and Authorization via cookies
VERSION
version 3.20
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::Apache::AuthCookieHandler
PerlSetVar WhatEverPath /
PerlSetVar WhatEverLoginScript /login.pl
# use to alter how "require" directives are matched. Can be "Any" or "All".
# If its "Any", then you must only match Any of the "require" directives. If
# its "All", then you must match All of the require directives.
#
# Default: All
PerlSetVar WhatEverSatisfy Any
# 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
# Use this if you want user session cookies to expire if the user
# doesn't request a auth-required or recognize_user page for some
# time period. If set, a new cookie (with updated expire time)
# is set on every request.
PerlSetVar WhatEverSessionTimeout +30m
# to enable the HttpOnly cookie property, use HttpOnly.
# this is an MS extension. See
# http://msdn.microsoft.com/workshop/author/dhtml/httponly_cookies.asp
PerlSetVar WhatEverHttpOnly 1
# Usually documents are uncached - turn off here
PerlSetVar WhatEverCache 1
# Use this to make your cookies persistent (+2 hours here)
PerlSetVar WhatEverExpires +2h
# Use to make AuthCookie send a P3P header with the cookie
# see http://www.w3.org/P3P/ for details about what the value
# of this should be
PerlSetVar WhatEverP3P "CP=\"...\""
# These documents require user to be logged in.
<Location /protected>
AuthType Sample::Apache::AuthCookieHandler
AuthName WhatEver
PerlAuthenHandler Sample::Apache::AuthCookieHandler->authenticate
PerlAuthzHandler Sample::Apache::AuthCookieHandler->authorize
require valid-user
</Location>
# These documents don't require logging in, but allow it.
<FilesMatch "\.ok$">
AuthType Sample::Apache::AuthCookieHandler
AuthName WhatEver
PerlFixupHandler Sample::Apache::AuthCookieHandler->recognize_user
</FilesMatch>
# This is the action of the login.pl script above.
<Files LOGIN>
AuthType Sample::Apache::AuthCookieHandler
AuthName WhatEver
SetHandler perl-script
PerlHandler Sample::Apache::AuthCookieHandler->login
</Files>
DESCRIPTION
Apache::AuthCookie allows you to intercept a user's first unauthenticated access to a
protected document. The user will be presented with a custom form where they can enter
authentication credentials. The credentials are posted to the server where AuthCookie
verifies them and returns a session key.
The session key is returned to the user's browser as a cookie. As a cookie, the browser
will pass the session key on every subsequent accesses. AuthCookie will verify the session
key and re-authenticate the user.
All you have to do is write a custom module that inherits from AuthCookie. Your module is
a class which implements two methods:
"authen_cred()"
Verify the user-supplied credentials and return a session key. The session key can be
any string - often you'll use some string containing username, timeout info, and any
other information you need to determine access to documents, and append a one-way hash
of those values together with some secret key.
"authen_ses_key()"
Verify the session key (previously generated by "authen_cred()", possibly during a
previous request) and return the user ID. This user ID will be fed to
"$r->connection->user()" to set Apache's idea of who's logged in.
By using AuthCookie versus Apache's built-in AuthBasic you can design your own
authentication system. There are several benefits.
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.
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.
3. AuthBasic dialog boxes are ugly. You can design your own HTML login forms when you
use AuthCookie.
4. You can specify the domain of a cookie using PerlSetVar commands. For instance, if
your AuthName is "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
".yourhost.com".
5. You can optionally specify the name of your cookie using the "CookieName" directive.
For instance, if your AuthName is "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.
6. By default users must satisfy ALL of the "require" directives. If you want
authentication to succeed if ANY "require" directives are met, use the "Satisfy"
directive. For instance, if your AuthName is "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 "require" directives are met.
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.
METHODS
"Apache::AuthCookie" has several methods you should know about. Here is the documentation
for each. =)
• authenticate()
This method is one you'll use in a server config file (httpd.conf, .htaccess, ...) as
a PerlAuthenHandler. If the user provided a session key in a cookie, the
"authen_ses_key()" method will get called to check whether the key is valid. If not,
or if there is no key provided, we redirect to the login form.
• authorize()
This will step through the "require" directives you've given for protected documents
and make sure the user passes muster. The "require valid-user" and "require user
joey-jojo" directives are handled for you. You can implement custom directives, such
as "require species hamster", by defining a method called "species()" in your
subclass, which will then be called. The method will be called as "$r->species($r,
$args)", where $args is everything on your "require" line after the word "species".
The method should return OK on success and FORBIDDEN on failure.
• authen_cred()
You must define this method yourself in your subclass of "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 ($$\@) {
my $self = shift; # Package name (same as AuthName directive)
my $r = shift; # Apache request object
my @cred = @_; # Credentials from login form
...blah blah blah, create a session key...
return $session_key;
}
The only limitation on the session key is that you should be able to look at it later
and determine the user's username. You are responsible for implementing your own
session key format. A typical format is to make a string that contains the username,
an expiration time, whatever else you need, and an MD5 hash of all that data together
with a secret key. The hash will ensure that the user doesn't tamper with the session
key. More info in the Eagle book.
• authen_ses_key()
You must define this method yourself in your subclass of Apache::AuthCookie. Its job
is to look at a session key and determine whether it is valid. If so, it returns the
username of the authenticated user.
sub authen_ses_key ($$$) {
my ($self, $r, $session_key) = @_;
...blah blah blah, check whether $session_key is valid...
return $ok ? $username : undef;
}
Optionally, return an array of 2 or more items that will be passed to method
custom_errors. It is the responsibility of this method to return the correct response
to the main Apache module.
• custom_errors($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
/three AND here
The authen_ses_key method would return a normal response when the user attempts to
access 'one' or 'three' but return (NOT_FOUND, 'File not found') if an attempt was
made to access subdirectory 'two'. Or, in the case of expired credentials,
(AUTH_REQUIRED,'Your session has timed out, you must login again').
example 'custom_errors'
sub custom_errors {
my ($self,$r,$CODE,$msg) = @_;
# return custom message else use the server's standard message
$r->custom_response($CODE, $msg) if $msg;
return($CODE);
}
where CODE is a valid code from Apache::Constants
• login()
This method handles the submission of the login form. It will call the
"authen_cred()" method, passing it $r and all the submitted data with names like
"credential_#", where # is a number. These will be passed in a simple array, so the
prototype is "$self->authen_cred($r, @credentials)". After calling "authen_cred()",
we set the user's cookie and redirect to the URL contained in the "destination"
submitted form field.
• login_form()
This method is responsible for displaying the login form. The default implementation
will make an internal redirect and display the URL you specified with the "PerlSetVar
WhatEverLoginScript" configuration directive. You can overwrite this method to provide
your own mechanism.
• login_form_status($r)
This method returns the HTTP status code that will be returned with the login form
response. The default behaviour is to return FORBIDDEN, except for some known
browsers which ignore HTML content for FORBIDDEN responses (e.g.: SymbianOS). You can
override this method to return custom codes.
Note that FORBIDDEN is the most correct code to return as the given request was not
authorized to view the requested page. You should only change this if FORBIDDEN does
not work.
• 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 "$r->auth_type->logout($r);".
• send_cookie($session_key)
By default this method simply sends out the session key you give it. If you need to
change the default behavior (perhaps to update a timestamp in the key) you can
override this method.
• recognize_user()
If the user has provided a valid session key but the document isn't protected, this
method will set "$r->connection->user" anyway. Use it as a PerlFixupHandler, unless
you have a better idea.
• key()
This method will return the current session key, if any. This can be handy inside a
method that implements a "require" directive check (like the "species" method
discussed above) if you put any extra information like clearances or whatever into the
session key.
• untaint_destination($self, $uri)
This method returns a modified version of the destination parameter before embedding
it into the response header. Per default it escapes CR, LF and TAB characters of the
uri to avoid certain types of security attacks. You can override it to more limit the
allowed destinations, e.g., only allow relative uris, only special hosts or only
limited set of characters.
EXAMPLE
For an example of how to use Apache::AuthCookie, you may want to check out the test suite,
which runs AuthCookie through a few of its paces. The documents are located in t/eg/, and
you may want to peruse t/real.t to see the generated httpd.conf file (at the bottom of
real.t) and check out what requests it's making of the server (at the top of real.t).
THE LOGIN SCRIPT
You will need to create a login script (called login.pl above) that generates an HTML form
for the user to fill out. You might generate the page using an Apache::Registry script,
or an HTML::Mason component, or perhaps even using a static HTML page. It's usually
useful to generate it dynamically so that you can define the 'destination' field correctly
(see below).
The following fields must be present in the form:
1. The ACTION of the form must be /LOGIN (or whatever you defined in your server
configuration as handled by the ->login() method - see example in the SYNOPSIS
section).
2. The various user input fields (username, passwords, etc.) must be named
'credential_0', 'credential_1', etc. on the form. These will get passed to your
authen_cred() method.
3. You must define a form field called 'destination' that tells AuthCookie where to
redirect the request after successfully logging in. Typically this value is obtained
from "$r->prev->uri". See the login.pl script in t/eg/.
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,
AuthCookie will set "$r->subprocess_env('AuthCookieReason')" to one of the following
values.
no_cookie
The user presented no cookie at all. Typically this means the user is trying to log
in for the first time.
bad_cookie
The cookie the user presented is invalid. Typically this means that the user is not
allowed access to the given page.
bad_credentials
The user tried to log in, but the credentials that were passed are invalid.
You can examine this value in your login form by examining
"$r->prev->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 "authen_ses_key()" method can set arbitrary entries in
"$r->subprocess_env".
THE LOGOUT SCRIPT
If you want to let users log themselves out (something that can't be done using Basic
Auth), you need to create a logout script. For an example, see t/htdocs/docs/logout.pl.
Logout scripts may want to take advantage of AuthCookie's "logout()" method, which will
set the proper cookie headers in order to clear the user's cookie. This usually looks
like "$r->auth_type->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.
ABOUT SESSION KEYS
Unlike the sample AuthCookieHandler, you have you verify the user's login and password in
"authen_cred()", then you do something like:
my $date = localtime;
my $ses_key = MD5->hexhash(join(';', $date, $PID, $PAC));
save $ses_key along with the user's login, and return $ses_key.
Now "authen_ses_key()" looks up the $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.
TO DO
• 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.
HISTORY
Originally written by Eric Bartley <bartley@purdue.edu>
versions 2.x were written by Ken Williams <ken@forum.swarthmore.edu>
SEE ALSO
perl(1), mod_perl(1), Apache(1).
SOURCE
The development version is on github at <http://github.com/mschout/apache-authcookie> and
may be cloned from <git://github.com/mschout/apache-authcookie.git>
BUGS
Please report any bugs or feature requests to bug-apache-authcookie@rt.cpan.org or through
the web interface at:
http://rt.cpan.org/Public/Dist/Display.html?Name=Apache-AuthCookie
AUTHOR
Michael Schout <mschout@cpan.org>
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.