DESCRIPTION

A user authentication and authorisation framework plugin for Dancer apps.

Makes it easy to require a user to be logged in to access certain routes, provides role-based access control, and supports various authentication methods/sources (config file, database, Unix system users, etc).

Designed to support multiple authentication realms and to be as extensible as possible, and to make secure password handling easy. The base class for auth providers makes handling "RFC2307"-style hashed passwords really simple, so you have no excuse for storing plain-text passwords. A simple script to generate RFC2307-style hashed passwords is included, or you can use Crypt::SaltedHash yourself to do so, or use the "slappasswd" utility if you have it installed.

SYNOPSIS

Configure the plugin to use the authentication provider class you wish to use:

plugins:
Auth::Extensible:
realms:
users:
provider: Example
....

The configuration you provide will depend on the authentication provider module in use. For a simple example, see Dancer::Plugin::Auth::Extensible::Provider::Config.

Define that a user must be logged in and have the proper permissions to access a route:

    get '/secret' => require_role Confidant => sub { tell_secrets(); };

Define that a user must be logged in to access a route - and find out who is logged in with the "logged_in_user" keyword:

    get '/users' => require_login sub {
        my $user = logged_in_user;
        return "Hi there, $user->{username}";
    };

AUTHENTICATION PROVIDERS

For flexibility, this authentication framework uses simple authentication provider classes, which implement a simple interface and do whatever is required to authenticate a user against the chosen source of authentication.

For an example of how simple provider classes are, so you can build your own if required or just try out this authentication framework plugin easily, see Dancer::Plugin::Auth::Extensible::Provider::Example.

This framework supplies the following providers out-of-the-box:

Dancer::Plugin::Auth::Extensible::Provider::Unix

Authenticates users using system accounts on Linux/Unix type boxes

Dancer::Plugin::Auth::Extensible::Provider::Database

Authenticates users stored in a database table

Dancer::Plugin::Auth::Extensible::Provider::Config

Authenticates users stored in the app's config

Need to write your own? Just subclass Dancer::Plugin::Auth::Extensible::Provider::Base and implement the required methods, and you're good to go!

CONTROLLING ACCESS TO ROUTES

Keywords are provided to check if a user is logged in / has appropriate roles.

require_login - require the user to be logged in

    get '/dashboard' => require_login sub { .... };

If the user is not logged in, they will be redirected to the login page URL to log in. The default URL is "/login" - this may be changed with the "login_page" option.

require_role - require the user to have a specified role

    get '/beer' => require_role BeerDrinker => sub { ... };

Requires that the user be logged in as a user who has the specified role. If the user is not logged in, they will be redirected to the login page URL. If they are logged in, but do not have the required role, they will be redirected to the access denied URL.

require_any_roles - require the user to have one of a list of roles

    get '/drink' => require_any_role [qw(BeerDrinker VodaDrinker)] => sub {
        ...
    };

Requires that the user be logged in as a user who has any one (or more) of the roles listed. If the user is not logged in, they will be redirected to the login page URL. If they are logged in, but do not have any of the specified roles, they will be redirected to the access denied URL.

require_all_roles - require the user to have all roles listed

    get '/foo' => require_all_roles [qw(Foo Bar)] => sub { ... };

Requires that the user be logged in as a user who has all of the roles listed. If the user is not logged in, they will be redirected to the login page URL. If they are logged in but do not have all of the specified roles, they will be redirected to the access denied URL.

Replacing the Default /login and /login/denied Routes

By default, the plugin adds a route to present a simple login form at that URL. If you would rather add your own, set the "no_default_pages" setting to a true value, and define your own route which responds to "/login" with a login page. Alternatively you can let DPAE add the routes and handle the status codes, etc. and simply define the setting "login_page_handler" and/or "permission_denied_page_handler" with the name of a subroutine to be called to handle the route. Note that it must be a fully qualified sub. E.g.

    plugins:
      Auth::Extensible:
        login_page_handler: 'My::App:login_page_handler'
        permission_denied_page_handler: 'My::App:permission_denied_page_handler'

Then in your code you might simply use a template:

    sub permission_denied_page_handler {
        template 'account/login';
    }

If the user is logged in, but tries to access a route which requires a specific role they don't have, they will be redirected to the ``permission denied'' page URL, which defaults to "/login/denied" but may be changed using the "denied_page" option.

Again, by default a route is added to respond to that URL with a default page; again, you can disable this by setting "no_default_pages" and creating your own.

This would still leave the routes "post '/login'" and "any '/logout'" routes in place. To disable them too, set the option "no_login_handler" to a true value. In this case, these routes should be defined by the user, and should do at least the following:

    post '/login' => sub {
        my ($success, $realm) = authenticate_user(
            params->{username}, params->{password}
        );
        if ($success) {
            session logged_in_user => params->{username};
            session logged_in_user_realm => $realm;
            # other code here
        } else {
            # authentication failed
        }
    };
    
    any '/logout' => sub {
        session->destroy;
    };

If you want to use the default "post '/login'" and "any '/logout'" routes you can configure them. See below.

Keywords

require_login

Used to wrap a route which requires a user to be logged in order to access it.

    get '/secret' => require_login sub { .... };

require_role

Used to wrap a route which requires a user to be logged in as a user with the specified role in order to access it.

    get '/beer' => require_role BeerDrinker => sub { ... };

You can also provide a regular expression, if you need to match the role using a regex - for example:

    get '/beer' => require_role qr/Drinker$/ => sub { ... };

require_any_role

Used to wrap a route which requires a user to be logged in as a user with any one (or more) of the specified roles in order to access it.

    get '/foo' => require_any_role [qw(Foo Bar)] => sub { ... };

require_all_roles

Used to wrap a route which requires a user to be logged in as a user with all of the roles listed in order to access it.

    get '/foo' => require_all_roles [qw(Foo Bar)] => sub { ... };

logged_in_user

Returns a hashref of details of the currently logged-in user, if there is one.

The details you get back will depend upon the authentication provider in use.

user_has_role

Check if a user has the role named.

By default, the currently-logged-in user will be checked, so you need only name the role you're looking for:

    if (user_has_role('BeerDrinker')) { pour_beer(); }

You can also provide the username to check;

    if (user_has_role($user, $role)) { .... }

user_roles

Returns a list of the roles of a user.

By default, roles for the currently-logged-in user will be checked; alternatively, you may supply a username to check.

Returns a list or arrayref depending on context.

authenticate_user

Usually you'll want to let the built-in login handling code deal with authenticating users, but in case you need to do it yourself, this keyword accepts a username and password, and optionally a specific realm, and checks whether the username and password are valid.

For example:

    if (authenticate_user($username, $password)) {
        ...
    }

If you are using multiple authentication realms, by default each realm will be consulted in turn. If you only wish to check one of them (for instance, you're authenticating an admin user, and there's only one realm which applies to them), you can supply the realm as an optional third parameter.

In boolean context, returns simply true or false; in list context, returns "($success, $realm)".

SAMPLE CONFIGURATION

In your application's configuation file:

    session: simple
    plugins:
        Auth::Extensible:
            # Set to 1 if you want to disable the use of roles (0 is default)
            disable_roles: 0
            # After /login: If no return_url is given: land here ('/' is default)
            user_home_page: '/user'
            # After /logout: If no return_url is given: land here (no default)
            exit_page: '/'
            
            # List each authentication realm, with the provider to use and the
            # provider-specific settings (see the documentation for the provider
            # you wish to use)
            realms:
                realm_one:
                    provider: Database
                        db_connection_name: 'foo'

Please note that you must have a session provider configured. The authentication framework requires sessions in order to track information about the currently logged in user. Please see Dancer::Session for information on how to configure session management within your application.

AUTHOR

David Precious, "<davidp at preshweb.co.uk>"

ACKNOWLEDGEMENTS

Valuable feedback on the early design of this module came from many people, including Matt S Trout (mst), David Golden (xdg), Damien Krotkine (dams), Daniel Perrett, and others.

Configurable login/logout URLs added by Rene (hertell)

Regex support for require_role by chenryn

Support for user_roles looking in other realms by Colin Ewen (casao)

LDAP provider added by Mark Meyer (ofosos)

Config options for default login/logout handlers by Henk van Oers (hvoers)

LICENSE AND COPYRIGHT

Copyright 2012-13 David Precious.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.