Catalyst::Plugin::Authentication(3p)

NAME
Catalyst::Plugin::Authentication - Infrastructure plugin for the Catalyst authentication framework.

SYNOPSIS
    use Catalyst qw/
        Authentication
    /;

    # later on ...
    $c->authenticate({ username => 'myusername',
                       password => 'mypassword' });
    my $age = $c->user->get('age');
    $c->logout;

DESCRIPTION
The authentication plugin provides generic user support for Catalyst apps. It is the basis for both authentication (checking the user is who they claim to be), and authorization (allowing the user to do what the system authorises them to do).

Using authentication is split into two parts. A Store is used to actually store the user information, and can store any amount of data related to the user. Credentials are used to verify users, using information from the store, given data from the frontend. A Credential and a Store are paired to form a 'Realm'. A Catalyst application using the authentication framework must have at least one realm, and may have several.

To implement authentication in a Catalyst application you need to add this module, and specify at least one realm in the configuration.

Authentication data can also be stored in a session, if the application is using the Catalyst::Plugin::Session module.

NOTE in version 0.10 of this module, the interface to this module changed. Please see "COMPATIBILITY ROUTINES" for more information.

INTRODUCTION

  The Authentication/Authorization Process
Web applications typically need to identify a user - to tell the user apart from other users. This is usually done in order to display private information that is only that user's business, or to limit access to the application so that only certain entities can access certain parts.

This process is split up into several steps. First you ask the user to identify themselves. At this point you can't be sure that the user is really who they claim to be.

Then the user tells you who they are, and backs this claim with some piece of information that only the real user could give you. For example, a password is a secret that is known to both the user and you. When the user tells you this password you can assume they're in on the secret and can be trusted (ignore identity theft for now). Checking the password, or any other proof is called credential verification.

By this time you know exactly who the user is - the user's identity is authenticated. This is where this module's job stops, and your application or other plugins step in.

The next logical step is authorization, the process of deciding what a user is (or isn't) allowed to do. For example, say your users are split into two main groups - regular users and administrators. You want to verify that the currently logged in user is indeed an administrator before performing the actions in an administrative part of your application. These decisions may be made within your application code using just the information available after authentication, or it may be facilitated by a number of plugins.

  The Components In This Framework
Realms

Configuration of the Catalyst::Plugin::Authentication framework is done in terms of realms. In simplest terms, a realm is a pairing of a Credential verifier and a User storage (Store) backend. As of version 0.10003, realms are now objects that you can create and customize.

An application can have any number of Realms, each of which operates independant of the others. Each realm has a name, which is used to identify it as the target of an authentication request. This name can be anything, such as 'users' or 'members'. One realm must be defined as the default_realm, which is used when no realm name is specified. More information about configuring realms is available in the configuration section.

Credential Verifiers

When user input is transferred to the Catalyst application (typically via form inputs) the application may pass this information into the authentication system through the "<$c-"authenticate()>> method. From there, it is passed to the appropriate Credential verifier.

These plugins check the data, and ensure that it really proves the user is who they claim to be.

Credential verifiers compatible with versions of this module 0.10x and upwards should be in the namespace "Catalyst::Authentication::Credential".

Storage Backends

The authentication data also identifies a user, and the Storage backend modules use this data to locate and return a standardized object-oriented representation of a user.

When a user is retrieved from a store it is not necessarily authenticated. Credential verifiers accept a set of authentication data and use this information to retrieve the user from the store they are paired with.

storage backends compatible with versions of this module 0.10x and upwards should be in the namespace "Catalyst::Authentication::Store".

The Core Plugin

This plugin on its own is the glue, providing realm configuration, session integration, and other goodness for the other plugins.

Other Plugins

More layers of plugins can be stacked on top of the authentication code. For example, Catalyst::Plugin::Session::PerUser provides an abstraction of browser sessions that is more persistent per user. Catalyst::Plugin::Authorization::Roles provides an accepted way to separate and group users into categories, and then check which categories the current user belongs to.

EXAMPLE
Let's say we were storing users in a simple perl hash. Users are verified by supplying a password which is matched within the hash.

This means that our application will begin like this:

    package MyApp;

    use Catalyst qw/
        Authentication
    /;

    __PACKAGE__->config->{'Plugin::Authentication'} =
                {
                    default_realm => 'members',
                    realms => {
                        members => {
                            credential => {
                                class => 'Password',
                                password_field => 'password',
                                password_type => 'clear'
                            },
                            store => {
                                class => 'Minimal',
                                users => {
                                    bob => {
                                        password => "s00p3r",
                                        editor => 'yes',
                                        roles => [qw/edit delete/],
                                    },
                                    william => {
                                        password => "s3cr3t",
                                        roles => [qw/comment/],
                                    }
                                }
                            }
                        }
                        }
                };

This tells the authentication plugin what realms are available, which credential and store modules are used, and the configuration of each. With this code loaded, we can now attempt to authenticate users.

To show an example of this, let's create an authentication controller:

    package MyApp::Controller::Auth;

    sub login : Local {
        my ( $self, $c ) = @_;

        if (    my $user     = $c->req->params->{user}
            and my $password = $c->req->params->{password"} )
        {
            if ( $c->authenticate( { username => $user,
                                     password => $password } ) ) {
                $c->res->body( "hello " . $c->user->get("name") );
            } else {
                # login incorrect
            }
        }
        else {
            # invalid form input
        }
    }

This code should be self-explanatory. If all the necessary fields are supplied, call the "authenticate" method on the context object. If it succeeds the user is logged in.

The credential verifier will attempt to retrieve the user whose details match the authentication information provided to "<$c-"authenticate()>>. Once it fetches the user the password is checked and if it matches the user will be authenticated and "<$c-"user>> will contain the user object retrieved from the store.

In the above case, the default realm is checked, but we could just as easily check an alternate realm. If this were an admin login, for example, we could authenticate on the admin realm by simply changing the "<$c-"authenticate()>> call:

    if ( $c->authenticate( { username => $user,
                             password => $password }, 'admin' ) ) {
        $c->res->body( "hello " . $c->user->get("name") );
    } ...

Now suppose we want to restrict the ability to edit to a user with an 'editor' value of yes.

The restricted action might look like this:

    sub edit : Local {
        my ( $self, $c ) = @_;

        $c->detach("unauthorized")
          unless $c->user_exists
          and $c->user->get('editor') eq 'yes';

        # do something restricted here
    }

(Note that if you have multiple realms, you can use "<$c-"user_in_realm('realmname')>>) in place of "<$c-"user_exists();>> This will essentially perform the same verification as user_exists, with the added requirement that if there is a user, it must have come from the realm specified.)

The above example is somewhat similar to role based access control. Catalyst::Authentication::Store::Minimal treats the roles field as an array of role names. Let's leverage this. Add the role authorization plugin:

    use Catalyst qw/
        ...
        Authorization::Roles
    /;

    sub edit : Local {
        my ( $self, $c ) = @_;

        $c->detach("unauthorized") unless $c->check_user_roles("edit");

        # do something restricted here
    }

This is somewhat simpler and will work if you change your store, too, since the role interface is consistent.

Let's say your app grew, and you now have 10000 users. It's no longer efficient to maintain a hash of users, so you move this data to a database. You can accomplish this simply by installing the DBIx::Class Store and changing your config:

    __PACKAGE__->config->{'Plugin::Authentication'} =
                    {
                        default_realm => 'members',
                        realms => {
                            members => {
                                credential => {
                                    class => 'Password',
                                    password_field => 'password',
                                    password_type => 'clear'
                                },
                                store => {
                                    class => 'DBIx::Class',
                                    user_class => 'MyApp::Users',
                                    role_column => 'roles'
                                }
                                }
                        }
                    };

The authentication system works behind the scenes to load your data from the new source. The rest of your application is completely unchanged.

CONFIGURATION
    # example
    __PACKAGE__->config->{'Plugin::Authentication'} =
                {
                    default_realm => 'members',
                    realms => {
                        members => {
                            credential => {
                                class => 'Password',
                                password_field => 'password',
                                password_type => 'clear'
                            },
                            store => {
                                class => 'DBIx::Class',
                                    user_class => 'MyApp::Users',
                                    role_column => 'roles'
                                }
                        },
                        admins => {
                            credential => {
                                class => 'Password',
                                password_field => 'password',
                                password_type => 'clear'
                            },
                            store => {
                                class => '+MyApp::Authentication::Store::NetAuth',
                                authserver => '192.168.10.17'
                            }
                        }

                        }
                };

use_session
    Whether or not to store the user's logged in state in the session, if the application is also using Catalyst::Plugin::Session. This value is set to true per default.

default_realm
    This defines which realm should be used as when no realm is provided to methods that require a realm such as authenticate or find_user.

realms
    This contains the series of realm configurations you want to use for your app. The only rule here is that there must be at least one. A realm consists of a name, which is used to reference the realm, a credential and a store.

    You can also specify a realm class to instantiate instead of the default Catalyst::Authentication::Realm class using the 'class' element within the realm config.

    Each realm config contains two hashes, one called 'credential' and one called 'store', each of which provide configuration details to the respective modules. The contents of these hashes is specific to the module being used, with the exception of the 'class' element, which tells the core Authentication module the classname to instantiate.

    The 'class' element follows the standard Catalyst mechanism of class specification. If a class is prefixed with a +, it is assumed to be a complete class name. Otherwise it is considered to be a portion of the class name. For credentials, the classname 'Password', for example, is expanded to Catalyst::Authentication::Credential::Password. For stores, the classname 'storename' is expanded to: Catalyst::Authentication::Store::storename.

METHODS

  $c->authenticate( $userinfo, [ $realm ])
Attempts to authenticate the user using the information in the $userinfo hash reference using the realm $realm. $realm may be omitted, in which case the default realm is checked.

  $c->user( )
Returns the currently logged in user or undef if there is none.

  $c->user_exists( )
Returns true if a user is logged in right now. The difference between user_exists and user is that user_exists will return true if a user is logged in, even if it has not been yet retrieved from the storage backend. If you only need to know if the user is logged in, depending on the storage mechanism this can be much more efficient.

  $c->user_in_realm( $realm )
Works like user_exists, except that it only returns true if a user is both logged in right now and was retrieved from the realm provided.

  $c->logout( )
Logs the user out, Deletes the currently logged in user from "<$c-"user>> and the session.

  $c->find_user( $userinfo, $realm )
Fetch a particular users details, matching the provided user info, from the realm specified in $realm.

  persist_user()
Under normal circumstances the user data is only saved to the session during initial authentication. This call causes the auth system to save the currently authenticated users data across requests. Useful if you have changed the user data and want to ensure that future requests reflect the most current data. Assumes that at the time of this call, $c->user contains the most current data.

INTERNAL METHODS
These methods are for Catalyst::Plugin::Authentication INTERNAL USE only. Please do not use them in your own code, whether application or credential / store modules. If you do, you will very likely get the nasty shock of having to fix / rewrite your code when things change. They are documented here only for reference.

  $c->set_authenticated( $user, $realmname )
Marks a user as authenticated. This is called from within the authenticate routine when a credential returns a user. $realmname defaults to 'default'

  $c->auth_restore_user( $user, $realmname )
Used to restore a user from the session. In most cases this is called without arguments to restore the user via the session. Can be called with arguments when restoring a user from some other method. Currently not used in this way.

  $c->auth_realms( )
Returns a hashref containing realmname -> realm instance pairs. Realm instances contain an instantiated store and credential object as the 'store' and 'credential' elements, respectively

  $c->get_auth_realm( $realmname )
Retrieves the realm instance for the realmname provided.

  $c->update_user_in_session
This was a short lived method to update user information - you should use persist_user instead.

SEE ALSO
This list might not be up to date. Below are modules known to work with the updated API of 0.10 and are therefore compatible with realms.

  Realms
Catalyst::Authentication::Realm

  User Storage Backends
Catalyst::Authentication::Store::Minimal, Catalyst::Authentication::Store::DBIx::Class,

  Credential verification
Catalyst::Authentication::Credential::Password,

  Authorization
Catalyst::Plugin::Authorization::ACL, Catalyst::Plugin::Authorization::Roles

  Internals Documentation
Catalyst::Plugin::Authentication::Internals

  Misc
Catalyst::Plugin::Session, Catalyst::Plugin::Session::PerUser

DON'T SEE ALSO
This module along with its sub plugins deprecate a great number of other modules. These include Catalyst::Plugin::Authentication::Simple, Catalyst::Plugin::Authentication::CDBI.

At the time of writing these plugins have not yet been replaced or updated, but should be eventually: Catalyst::Plugin::Authentication::OpenID, Catalyst::Plugin::Authentication::LDAP, Catalyst::Plugin::Authentication::CDBI::Basic, Catalyst::Plugin::Authentication::Basic::Remote.

INCOMPATABILITIES
The realms based configuration and functionality of the 0.10 update of Catalyst::Plugin::Authentication required a change in the API used by credentials and stores. It has a compatibility mode which allows use of modules that have not yet been updated. This, however, completely mimics the older api and disables the new realm-based features. In other words you can not mix the older credential and store modules with realms, or realm-based configs. The changes required to update modules are relatively minor and are covered in Catalyst::Plugin::Authentication::Internals. We hope that most modules will move to the compatible list above very quickly.

COMPATIBILITY ROUTINES
In version 0.10 of Catalyst::Plugin::Authentication, the API changed. For app developers, this change is fairly minor, but for Credential and Store authors, the changes are significant.

Please see the documentation in version 0.09 of Catalyst::Plugin::Authentication for a better understanding of how the old API functioned.

The items below are still present in the plugin, though using them is deprecated. They remain only as a transition tool, for those sites which can not yet be upgraded to use the new system due to local customizations or use of Credential / Store modules that have not yet been updated to work with the new API.

These routines should not be used in any application using realms functionality or any of the methods described above. These are for reference purposes only.

  $c->login( )
This method is used to initiate authentication and user retrieval. Technically this is part of the old Password credential module and it still resides in the Password class. It is included here for reference only.

  $c->default_auth_store( )
Return the store whose name is 'default'.

This is set to "$c->config->{'Plugin::Authentication'}{store}" if that value exists, or by using a Store plugin:

    # load the Minimal authentication store.
        use Catalyst qw/Authentication Authentication::Store::Minimal/;

Sets the default store to Catalyst::Plugin::Authentication::Store::Minimal.

  $c->get_auth_store( $name )
Return the store whose name is $name.

  $c->get_auth_store_name( $store )
Return the name of the store $store.

  $c->auth_stores( )
A hash keyed by name, with the stores registered in the app.

  $c->register_auth_stores( %stores_by_name )
Register stores into the application.

  $c->auth_store_names( )

  $c->get_user( )

  $c->setup( )

  $c->setup_auth_realm( )

AUTHORS
Yuval Kogman, "nothingmuch@woobling.org"

Jay Kuri, "jayk@cpan.org"

Jess Robinson

David Kamholz

COPYRIGHT & LICENSE
        Copyright (c) 2005 the aforementioned authors. All rights
        reserved. This program is free software; you can redistribute
        it and/or modify it under the same terms as Perl itself.