NAME

Dancer2::Plugin::Auth::Extensible - extensible authentication framework for Dancer2 apps

DESCRIPTION

A user authentication and authorisation framework plugin for Dancer2 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 called generate-crypted-password 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: Config
                  ....

The configuration you provide will depend on the authentication provider module in use. For a simple example, see Dancer2::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 Dancer2::Plugin::Auth::Extensible::Provider::Config.

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

Dancer2::Plugin::Auth::Extensible::Provider::Unix: Authenticates users using system accounts on Linux/Unix type boxes
Dancer2::Plugin::Auth::Extensible::Provider::Config: Authenticates users stored in the app's config

The following external providers are also available on the CPAN:

Dancer2::Plugin::Auth::Extensible::Provider::DBIC: Authenticates users stored in a database table using Dancer2::Plugin::DBIC
Dancer2::Plugin::Auth::Extensible::Provider::Database: Authenticates users stored in a database table
Dancer2::Plugin::Auth::Extensible::Provider::IMAP: Authenticates users via in an IMAP server.
Dancer2::Plugin::Auth::Extensible::Provider::LDAP: Authenticates users stored in an LDAP directory.
Dancer2::Plugin::Auth::Extensible::Provider::Usergroup: An alternative Dancer2::Plugin::DBIC-based provider.

Need to write your own? Just create a new provider class which consumes Dancer2::Plugin::Auth::Extensible::Role::Provider and implements 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.

If disable_roles configuration option is set to a true value then using "require_role" will cause the application to croak on load.

require_any_role - 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.

If disable_roles configuration option is set to a true value then using "require_any_roles" will cause the application to croak on load.

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.

If disable_roles configuration option is set to a true value then using "require_all_roles" will cause the application to croak on load.

By default when a page is requested that requires login and the user is not logged in then the plugin redirects the user to the "login_page" and sets return_url to the page originally requested. After successful login the user is redirected to the originally-requested page.

As an alternative if "login_without_redirect" is true then the login process happens with no redirects. Instead a 401 Unauthorized code is returned and a login page is displayed. This login page is posted to the original URI and on successful login an internal "forward" in Dancer2::Manual is performed so that the originally requested page is displayed. Any "params" in Dancer2::Manual from the original request are added to the forward so that they are available to the page's route handler either using "params" in Dancer2::Manual or "query_parameters" in Dancer2::Manual.

This relies on the login form having no action set and also it must use __auth_extensible_username and __auth_extensible_password input names. Optionally __auth_extensible_realm can also be used in a custom login page.

See http://shadow.cat/blog/matt-s-trout/humane-login-screens/ for the original idea for this functionality.

CUSTOMISING `/login` AND `/login/denied`

login_template

The "login_template" setting determines the name of the view you use for your custom login page. If this view exists in your application then it will be used instead of the default login template.

If you are using "login_without_redirect" and assuming you are using Template::Toolkit then your custom login page should be something like this:

<h1>Login Required</h1>

<p>You need to log in to continue.</p>

[%- IF login_failed -%]
    <p>LOGIN FAILED</p>
[%- END -%]

<form method="post">
    <label for="username">Username:</label>
    <input type="text" name="__auth_extensible_username" id="username">
    <br />
    <label for="password">Password:</label>
    <input type="password" name="__auth_extensible_password" id="password">
    <br />
    <input type="submit" value="Login">
</form>

[%- IF reset_password_handler -%]
<form method="post" action="[% login_page %]">
    <h2>Password reset</h2>
    <p>Enter your username to obtain an email to reset your password</p>
    <label for="username_reset">Username:</label>
    <input type="text" name="username_reset" id="username_reset">
    <input type="submit" name="submit_reset" value="Submit">
</form>
[%- END -%]

If you are not using "login_without_redirect" and assuming you are using Template::Toolkit then your custom login page should be something like this:

<h1>Login Required</h1>

<p>You need to log in to continue.</p>

[%- IF login_failed -%]
    <p>LOGIN FAILED</p>
[%- END -%]

<form method="post">
    <label for="username">Username:</label>
    <input type="text" name="username" id="username">
    <br />
    <label for="password">Password:</label>
    <input type="password" name="password" id="password">
    <br />
    <input type="submit" value="Login">

    [%- IF return_url -%]
        <input type="hidden" name="return_url" value="[% return_url %]">
    [%- END -%]

    [%- IF reset_password_handler -%]
        <h2>Password reset</h2>
        <p>Enter your username to obtain an email to reset your password</p>
        <label for="username_reset">Username:</label>
        <input type="text" name="username_reset" id="username_reset">
        <input type="submit" name="submit_reset" value="Submit">
    [%- END -%]

</form>

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) {
        # change session ID if we have a new enough D2 version with support
        # (security best practice on privilege level change)
        app->change_session_id
            if app->can('change_session_id');
        session logged_in_user => params->{username};
        session logged_in_user_realm => $realm;
        # other code here
    } else {
        # authentication failed
    }
};

any '/logout' => sub {
    app->destroy_session;
};

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

The default routes also contain functionality for a user to perform password resets. See the "PASSWORD RESETS" documentation for more details.

KEYWORDS

The following keywords are provided in additional to the route decorators specified in "CONTROLLING ACCESS TO ROUTES":

logged_in_user

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

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

get_user_details

Returns a hashref of details of the specified user. The realm can optionally be specified as the second parameter. If the realm is not specified, each realm will be checked, and the first matching user will be returned.

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)) { .... }

If disable_roles configuration option is set to a true value then using "user_has_role" will cause the application to croak at runtime.

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.

If disable_roles configuration option is set to a true value then using "user_roles" will cause the application to croak at runtime.

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).

logged_in_user_lastlogin

Returns (as a DateTime object) the time of the last successful login of the current logged in user.

To enable this functionality, set the configuration key record_lastlogin to a true value. The backend provider must support write access for a user and have lastlogin functionality implemented.

update_user

Updates a user's details. If the authentication provider supports it, this keyword allows a user's details to be updated within the backend data store.

In order to update the user's details, the keyword should be called with the username to be updated, followed by a hash of the values to be updated. Note that whilst the password can be updated using this method, any new value will be stored directly into the provider as-is, not encrypted. It is recommended to use "user_password" instead.

If only one realm is configured then this will be used to search for the user. Otherwise, the realm must be specified with the realm key.

# Update user, only one realm configured
update_user "jsmith", surname => "Smith"

# Update a user's username, more than one realm
update_user "jsmith", realm => "dbic", username => "jjones"

The updated user's details are returned, as per logged_in_user.

update_current_user

The same as update_user, but does not take a username as the first parameter, instead updating the currently logged-in user.

# Update user, only one realm configured
update_current_user surname => "Smith"

The updated user's details are returned, as per logged_in_user.

create_user

Creates a new user, if the authentication provider supports it. Optionally sends a welcome message with a password reset request, in which case an email key must be provided.

This function works in the same manner as update_user, except that the username key is mandatory. As with update_user, it is recommended not to set a password directly using this method, otherwise it will be stored in plain text.

The realm to use must be specified with the key realm if there is more than one realm configured.

# Create new user
create_user username => "jsmith", realm => "dbic", surname => "Smith"

# Create new user and send welcome email
create_user username => "jsmith", email => "john@you.com", email_welcome => 1

On success, the created user's details are returned, as per logged_in_user.

The text sent in the welcome email can be customised in 2 ways, in the same way as password_reset_send:

welcome_send

This can be used to specify a subroutine that will be called to perform the entire message construction and email sending. Note that it must be a fully-qualified sub such as My::App:email_welcome_send. The subroutine will be passed the dsl as the first parameter, followed by a hash with the keys code, email and user, which contain the generated reset code, user email address, and user hashref respectively. For example:

sub reset_send_handler {
    my ($dsl, %params) = @_;
    my $user_email = $params{email};
    my $reset_code = $params{code};
    # Send email
    return $result;
}

welcome_text

This can be used to generate the text for the welcome email, with this module sending the actual email itself. It must be a fully-qualified sub, as per the previous option. It will be passed the same parameters as welcome_send, and should return a hash with the same keys as password_reset_send_email.

password_reset_send

"password_reset_send" sends a user an email with a password reset link. Along with "user_password", it allows a user to reset their password.

The function must be called with the key username and a value that is the username. The username specified will be sent an email with a link to reset their password. Note that the provider being used must return the email address in the key email, which in the case of a database will normally require that column to exist in the user's table. The provider must be able to write values to the user in order for this function to store the generated code.

If the username is not found, a value of 0 is returned. If the username is found and the email is sent successfully, 1 is returned. Otherwise undef is returned. Note: if you are displaying a success message, and you do not want people to be able to check the existance of a user on your system, then you should check for the return value being defined, not true. For example:

say "Success" if defined password_reset_send username => username;

Note that this still leaves the possibility of checking the existance of a user if the email send mechanism is failing.

The realm can also be specified using the key realm:

password_reset_send username => 'jsmith', realm => 'dbic'

Default text for the email is automatically produced and emailed. This can be customized with one of 2 config parameters:

password_reset_send_email

This can be used to specify a subroutine that will be called to perform the entire message construction and email sending. Note that it must be a fully-qualified sub such as My::App:reset_send_handler. The subroutine will be passed the dsl as the first parameter, followed by a hash with the keys code and email, which contain the generated reset code and user email address respectively. For example:

sub reset_send_handler {
    my ($dsl, %params) = @_;
    my $user_email = $params{email};
    my $reset_code = $params{code};
    # Send email
    return $result;
}

password_reset_text

This can be used to generate the text for the email, with this module sending the actual email itself. It must be a fully-qualified sub, as per the previous option. It will be passed the same parameters as password_reset_send_email, and should return a hash with the following keys:

subject: The subject of the email message.
from: The sender of the email message (optional, can also be specified using mail_from.
plain: Plain text for the email. Either this, or html, or both should be returned.
html: HTML text for the email (optional, as per plain).

Here is an example subroutine:

sub reset_text_handler {
    my ($dsl, %params) = @_;
    return (
        from    => '"My name" <myapp@example.com',
        subject => 'the subject',
        plain   => "reset here: $params{code}",
    );
}

# Example configuration

Auth::Extensible:
    mailer:
        module: Mail::Message # Module to send email with
        options:              # Module options
            via: sendmail
    mail_from: '"My app" <myapp@example.com>'
    password_reset_text: MyApp::reset_send

user_password

This provides various functions to check or reset a user's password, either from a reset code that was previously send by password_reset_send or directly by specifying a username and password. Functions that update a password rely on a provider that has write access to a user's details.

By default, the user to update is the currently logged-in user. A specific user can be specified with the key username for a certain username, or code for a previously sent reset code. Using these parameters on their own will return the username if it is a valid request.

If the above parameters are specified with the additional parameter new_password, then the password will be set to that value, assuming that it is a valid request.

The realm can be optionally specified with the keyword realm.

Examples:

Check the logged-in user's password:

user_password password => 'mysecret'

Check a specific user's password:

user_password username => 'jsmith', password => 'bigsecret'

Check a previously sent reset code:

user_password code => 'XXXX'

Reset a password with a previously sent code:

user_password code => 'XXXX', new_password => 'newsecret'

Change a user's password (username optional)

user_password username => 'jbloggs', password => 'old', new_password => 'secret'

Force set a specific user's password, without checking existing password:

user_password username => 'jbloggs', new_password => 'secret'

logged_in_user_password_expired

Returns true if the password of the currently logged in user has expired. To use this functionality, the provider must support the password_expired function, and must be configured accordingly. See the relevant provider for full configuration details.

Note that this functionality does not prevent the user accessing any protected pages, even if the password has expired. This is so that the developer can still leave some protected routes available, such as a page to change the password. Therefore, if using this functionality, it is suggested that a check is done in the before hook:

hook before => sub {
    if (logged_in_user_password_expired)
    {
        # Redirect to user details page if password expired, but only if that
        # is not the currently request page to prevent redirect loops
        redirect '/password_update' unless request->uri eq '/password_update';
    }
}

PASSWORD RESETS

A variety of functionality is provided to make it easier to manage requests from users to reset their passwords. The keywords password_reset_send and user_password form the core of this functionality - see the documentation of these keywords for full details. This functionality can only be used with a provider that supports write access.

When utilising this functionality, it is wise to only allow passwords to be reset with a POST request. This is because some email scanners "open" links before delivering the email to the end user. With only a single-use GET request, this will result in the link being "used" by the time it reaches the end user, thus rendering it invalid.

Password reset functionality is also built-in to the default route handlers. To enable this, set the configuration value reset_password_handler to a true value (having already configured the mail handler, as per the keyword documentation above). Once this is done, the default login page will contain additional form controls to allow the user to enter their username and request a reset password link.

By default, the default handlers will generate a random 8 character password using Session::Token. To use your own function, set password_generator in your configuration. See the "SAMPLE CONFIGURATION" for an example.

If using login_page_handler to replace the default login page, you can still use the default password reset handlers. Add 2 controls to your form for submitting a password reset request: a text input called username_reset for the username, and submit_reset to submit the request. Your login_page_handler is then passed the following additional params:

new_password

Contains the new automatically-generated password, once the password reset has been performed successfully.

reset_sent

Is true when a password reset has been emailed to the user.

password_code_valid

Is true when a valid password reset code has been submitted with a GET request. In this case, the user should be given the chance to confirm with a POST request, with a form control called confirm_reset.

For a full example, see the default handler in this module's code.

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)
        # If roles are disabled then any use of role-based route decorators
        # will cause app to croak on load. Use of 'user_roles' and
        # 'user_has_role' will croak at runtime.
        disable_roles: 0
        # Set to 1 to use the no-redirect login functionality
        login_without_redirect: 0
        # Set the view name for a custom login page, defaults to 'login'
        login_template: login
        # 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: '/'

        # Mailer options for reset password and welcome emails
        mailer:
            module: Mail::Message # Email module to use
            options:              # Options for module
                via: sendmail     # Options passed to $msg->send
        mail_from: '"App name" <myapp@example.com>' # From email address

        # Set to true to enable password reset code in the default handlers
        reset_password_handler: 1
        password_generator: My::App::random_pw # Optional random password generator

        # Set to a true value to enable recording of successful last login times
        record_lastlogin: 1

        # Password reset functionality
        password_reset_send_email: My::App::reset_send # Customise sending sub
        password_reset_text: My::App::reset_text # Customise reset text

        # create_user options
        welcome_send: My::App::welcome_send # Customise welcome email sub
        welcome_text: My::App::welcome_text # Customise welcome email text

        # 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:
                priority: 3 # Defaults to 0. Realms are checked in descending order
                provider: Database
                    db_connection_name: 'foo'
            realm_two:
                priority: 0 # Will be checked after realm_one
                provider: Config

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 Dancer2::Core::Session for information on how to configure session management within your application.

METHODS

auth_provider($dsl, $realm)

Given a realm, returns a configured and ready to use instance of the provider specified by that realm's config.

HOOKS

This plugin provides the following hooks:

before_authenticate_user

Called at the start of "authenticate_user".

Receives a hash reference of username, password and realm.

after_authenticate_user

Called at the end of "authenticate_user".

Receives a hash reference of username, password, realm, errors and success.

realm is the realm that the user authenticated against of undef if auth failed.

The value of errors is an array reference of any errors thrown by authentication providers (if any).

The value of success is either 1 or 0 to show whether or not authentication was successful.

before_create_user

Called at the start of "create_user".

Receives a hash reference of the arguments passed to "create_user".

after_create_user

Called at the end of "create_user".

Receives the requested username, the created user (or undef) and an array reference of any errors from the main method or from the provider.

login_required

permission_denied

after_login_success

Called after successful login just before redirect is called.

AUTHOR

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

Dancer2 port of Dancer::Plugin::Auth::Extensible by:

Stefan Hornburg (Racke), <racke at linuxia.de>

Conversion to Dancer2's new plugin system plus much cleanup & reorg:

Peter Mottram (SysPete), <peter at sysnix.com>

BUGS / FEATURE REQUESTS

This is an early version; there may still be bugs present or features missing.

This is developed on GitHub - please feel free to raise issues or pull requests against the repo at: https://github.com/PerlDancer/Dancer2-Plugin-Auth-Extensible

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)

Documentation fix by Vince Willems.

Henk van Oers (GH #8, #13, #55).

Andrew Beverly (GH #6, #7, #10, #17, #22, #24, #25, #26, #54). This includes support for creating and editing users and manage user passwords.

Gabor Szabo (GH #11, #16, #18).

Evan Brown (GH #20, #32).

Jason Lewis (Unix provider problem).

Matt S. Trout (mst) for Zero redirect login the easy and friendly way.

LICENSE AND COPYRIGHT

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.

To install Dancer2::Plugin::Auth::Extensible, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Dancer2::Plugin::Auth::Extensible

CPAN shell

perl -MCPAN -e shell
install Dancer2::Plugin::Auth::Extensible

For more information on module installation, please visit the detailed CPAN module installation guide.

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