NAME

Catalyst::Manual::Tutorial::Authentication - Catalyst Tutorial - Part 4: Authentication

OVERVIEW

This is Part 4 of 9 for the Catalyst tutorial.

DESCRIPTION

Now that we finally have a simple yet functional application, we can focus on providing authentication (with authorization coming next in Part 5).

This part of the tutorial is divided into two main sections: 1) basic, cleartext authentication and 2) hash-based authentication.

TIP: Note that all of the code for this part of the tutorial can be pulled from the Catalyst Subversion repository in one step with the following command:

    svn checkout http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/Tutorial@###
    IMPORTANT: Does not work yet.  Will be completed for final version.

BASIC AUTHENTICATION

This section explores how to add authentication logic to a Catalyst application.

Add Users and Roles to the Database

First, we add both user and role information to the database (we will add the role information here although it will not be used until the authorization section, Part 5). Create a new SQL script file by opening myapp02.sql in your editor and insert:

    --
    -- Add users and roles tables, along with a many-to-many join table
    --
    CREATE TABLE users (
            id            INTEGER PRIMARY KEY,
            username      TEXT,
            password      TEXT,
            email_address TEXT,
            first_name    TEXT,
            last_name     TEXT,
            active        INTEGER
    );
    CREATE TABLE roles (
            id   INTEGER PRIMARY KEY,
            role TEXT
    );
    CREATE TABLE user_roles (
            user_id INTEGER,
            role_id INTEGER,
            PRIMARY KEY (user_id, role_id)
    );
    --
    -- Load up some initial test data
    --
    INSERT INTO users VALUES (1, 'test01', 'mypass', 't01@na.com', 'Joe',  'Blow', 1);
    INSERT INTO users VALUES (2, 'test02', 'mypass', 't02@na.com', 'Jane', 'Doe',  1);
    INSERT INTO users VALUES (3, 'test03', 'mypass', 't03@na.com', 'No',   'Go',   0);
    INSERT INTO roles VALUES (1, 'user');
    INSERT INTO roles VALUES (2, 'admin');
    INSERT INTO user_roles VALUES (1, 1);
    INSERT INTO user_roles VALUES (1, 2);
    INSERT INTO user_roles VALUES (2, 1);
    INSERT INTO user_roles VALUES (3, 1);

Then load this into the myapp.db database with the following command:

    $ sqlite3 myapp.db < myapp02.sql

Add User and Role Information to DBIC Schema

This step adds DBIC-based classes for the user-related database tables (the role information will not be used until Part 5):

Edit lib/MyAppDB.pm and update the contents to match (only the MyAppDB => [qw/Book BookAuthor Author User UserRole Role/] line has changed):

    package MyAppDB;
    
    =head1 NAME 
    
    MyAppDB -- DBIC Schema Class
    
    =cut
    
    # Our schema needs to inherit from 'DBIx::Class::Schema'
    use base qw/DBIx::Class::Schema/;
    
    # Need to load the DB Model classes here.
    # You can use this syntax if you want:
    #    __PACKAGE__->load_classes(qw/Book BookAuthor Author User UserRole Role/);
    # Also, if you simply want to load all of the classes in a directory
    # of the same name as your schema class (as we do here) you can use:
    #    __PACKAGE__->load_classes(qw//);
    # But the variation below is more flexible in that it can be used to 
    # load from multiple namespaces.
    __PACKAGE__->load_classes({
        MyAppDB => [qw/Book BookAuthor Author User UserRole Role/]
    });
    
    1;

Create New "Result Source Objects"

Create the following three files with the content shown below.

lib/MyAppDB/User.pm:

    package MyAppDB::User;
    
    use base qw/DBIx::Class/;
    
    # Load required DBIC stuff
    __PACKAGE__->load_components(qw/PK::Auto Core/);
    # Set the table name
    __PACKAGE__->table('users');
    # Set columns in table
    __PACKAGE__->add_columns(qw/id username password email_address first_name last_name/);
    # Set the primary key for the table
    __PACKAGE__->set_primary_key('id');
    
    #
    # Set relationships:
    #
    
    # has_many():
    #   args:
    #     1) Name of relationship, DBIC will create accessor with this name
    #     2) Name of the model class referenced by this relationship
    #     3) Column name in *foreign* table
    __PACKAGE__->has_many(map_user_role => 'MyAppDB::UserRole', 'user_id');
    
    
    =head1 NAME
    
    MyAppDB::User - A model object representing a person with access to the system.
    
    =head1 DESCRIPTION
    
    This is an object that represents a row in the 'users' table of your application
    database.  It uses DBIx::Class (aka, DBIC) to do ORM.
    
    For Catalyst, this is designed to be used through MyApp::Model::MyAppDB.
    Offline utilities may wish to use this class directly.
    
    =cut
    
    1;

lib/MyAppDB/Role.pm:

    package MyAppDB::Role;
    
    use base qw/DBIx::Class/;
    
    # Load required DBIC stuff
    __PACKAGE__->load_components(qw/PK::Auto Core/);
    # Set the table name
    __PACKAGE__->table('roles');
    # Set columns in table
    __PACKAGE__->add_columns(qw/id role/);
    # Set the primary key for the table
    __PACKAGE__->set_primary_key('id');
    
    #
    # Set relationships:
    #
    
    # has_many():
    #   args:
    #     1) Name of relationship, DBIC will create accessor with this name
    #     2) Name of the model class referenced by this relationship
    #     3) Column name in *foreign* table
    __PACKAGE__->has_many(map_user_role => 'MyAppDB::UserRole', 'role_id');
    
    
    =head1 NAME
    
    MyAppDB::Role - A model object representing a class of access permissions to 
    the system.
    
    =head1 DESCRIPTION
    
    This is an object that represents a row in the 'roles' table of your 
    application database.  It uses DBIx::Class (aka, DBIC) to do ORM.
    
    For Catalyst, this is designed to be used through MyApp::Model::MyAppDB.
    "Offline" utilities may wish to use this class directly.
    
    =cut
    
    1;

lib/MyAppDB/UserRole.pm:

    package MyAppDB::UserRole;
    
    use base qw/DBIx::Class/;
    
    # Load required DBIC stuff
    __PACKAGE__->load_components(qw/PK::Auto Core/);
    # Set the table name
    __PACKAGE__->table('user_roles');
    # Set columns in table
    __PACKAGE__->add_columns(qw/user_id role_id/);
    # Set the primary key for the table
    __PACKAGE__->set_primary_key(qw/user_id role_id/);
    
    #
    # Set relationships:
    #
    
    # belongs_to():
    #   args:
    #     1) Name of relationship, DBIC will create accessor with this name
    #     2) Name of the model class referenced by this relationship
    #     3) Column name in *this* table
    __PACKAGE__->belongs_to(user => 'MyAppDB::User', 'user_id');
    
    # belongs_to():
    #   args:
    #     1) Name of relationship, DBIC will create accessor with this name
    #     2) Name of the model class referenced by this relationship
    #     3) Column name in *this* table
    __PACKAGE__->belongs_to(role => 'MyAppDB::Role', 'role_id');
    
    
    =head1 NAME
    
    MyAppDB::UserRole - A model object representing the JOIN between Users and Roles.
    
    =head1 DESCRIPTION
    
    This is an object that represents a row in the 'user_roles' table of your application
    database.  It uses DBIx::Class (aka, DBIC) to do ORM.
    
    You probably won't need to use this class directly -- it will be automatically
    used by DBIC where joins are needed.
    
    For Catalyst, this is designed to be used through MyApp::Model::MyAppDB.
    Offline utilities may wish to use this class directly.
    
    =cut
    
    1;

The code for these three result source classes is obviously very familiar to the Book, Author, and BookAuthor classes created in Part 2.

Sanity-Check Reload of Development Server

We aren't ready to try out the authentication just yet; we only want to do a quick check to be sure our model loads correctly. Press Ctrl-C to kill the previous server instance (if it's still running) and restart it:

    $ script/myapp_server.pl

Look for the three new model objects in the startup debug output:

    ...
     .-------------------------------------------------------------------+----------.
    | Class                                                             | Type     |
    +-------------------------------------------------------------------+----------+
    | MyApp::Controller::Books                                          | instance |
    | MyApp::Controller::Root                                           | instance |
    | MyApp::Model::MyAppDB                                             | instance |
    | MyApp::Model::MyAppDB::Author                                     | class    |
    | MyApp::Model::MyAppDB::Book                                       | class    |
    | MyApp::Model::MyAppDB::BookAuthor                                 | class    |
    | MyApp::Model::MyAppDB::Role                                       | class    |
    | MyApp::Model::MyAppDB::User                                       | class    |
    | MyApp::Model::MyAppDB::UserRole                                   | class    |
    | MyApp::View::TT                                                   | instance |
    '-------------------------------------------------------------------+----------'
    ...

Again, notice that your "result source" classes have been "re-loaded" by Catalyst under MyApp::Model.

Include Authentication and Session Plugins

Edit lib/MyApp.pm and update it as follows (everything below DefaultEnd is new):

    use Catalyst qw/
            -Debug
            ConfigLoader
            Static::Simple
            
            StackTrace
            DefaultEnd
            
            Authentication
            Authentication::Store::DBIC
            Authentication::Credential::Password
            
            Session
            Session::Store::FastMmap
            Session::State::Cookie
            /;

The three Authentication plugins work together to support Authentication while the Session plugins are required to maintain state across multiple HTTP requests. Note that there are several options for Session::Store (although Session::Store::FastMmap is generally a good choice if you are on Unix; try Cache::FileCache if you are on Win32) -- consult Session::Store and its subclasses for additional information.

Configure Authentication

Although __PACKAGE__->config(name => 'value'); is still supported, newer Catalyst applications tend to place all configuration information in myapp.yml and automatically load this information into MyApp->config using the ConfigLoader plugin.

Edit the myapp.yml YAML and update it to match:

    ---
    name: MyApp
    authentication:
        dbic:
            # Note this first definition would be the same as setting
            # __PACKAGE__->config->{authentication}->{dbic}->{user_class} = 'MyAppDB::User'
            # in lib/MyApp.pm (IOW, each hash key becomes a "name:" in the YAML file).
            #
            # This is the model object created by Catalyst::Model::DBIC from your
            # schema (you created 'MyAppDB::User' but as the Catalyst startup
            # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::User').
            # NOTE: Omit 'MyAppDB::Model' to avoid a component lookup issue in Catalyst 5.66
            user_class: MyAppDB::User
            # This is the name of the field in your 'users' table that contains the user's name
            user_field: username
            # This is the name of the field in your 'users' table that contains the password
            password_field: password
            # Other options can go here for hashed passwords

Inline comments in the code above explain how each field is being used.

TIP: Although YAML uses a very simple and easy-to-ready format, it does require the use of a consistent level of indenting. Be sure you line up everything on a given 'level' with the same number of indents. Also, be sure not to use tab characters (YAML does not support them because they are handled inconsistently across editors).

Use the Catalyst create script to create two stub controller files:

    $ script/myapp_create.pl controller Login
    $ script/myapp_create.pl controller Logout

NOTE: You could easily use a single controller here. For example, you could have a User controller with both login and logout actions. Remember, Catalyst is designed to be very flexible, and leaves such matters up to you, the designer and programmer.

Then open lib/MyApp/Controller/Login.pm and add:

    =head2 default
    
    Login logic
    
    =cut
    
    sub default : Private {
        my ($self, $c) = @_;
    
        # Get the username and password from form
        my $username = $c->request->params->{username} || "";
        my $password = $c->request->params->{password} || "";
    
        # If the username and password values were found in form
        if ($username && $password) {
            # Attempt to log the user in
            if ($c->login($username, $password)) {
                # If successful, then let them use the application
                $c->response->redirect($c->uri_for('/books/list'));
                return;
            } else {
                # Set an error message
                $c->stash->{error_msg} = "Bad username or password.";
            }
        }
    
        # If either of above don't work out, send to the login page
        $c->stash->{template} = 'login.tt2';
    }

This controller fetches the username and password values from the login form and attempts to perform a login. If successful, it redirects the user to the book list page. If the login fails, the user will stay at the login page but receive an error message. If the username and password values are not present in the form, the user will be taken to the empty login form.

Next, create a corresponding method in lib/MyApp/Controller/Logout.pm:

    =head2 default
    
    Logout logic
    
    =cut
    
    sub default : Private {
        my ($self, $c) = @_;
    
        # Clear the user's state
        $c->logout;
    
        # Send the user to the starting point
        $c->response->redirect($c->uri_for('/'));
    }

Create a login form by opening root/src/login.tt2 and inserting:

    [% META title = 'Login' %]
    
    <!-- Login form -->
    <form method="post" action=" [% Catalyst.uri_for('/login') %] ">
      <table>
        <tr>
          <td>Username:</td>
          <td><input type="text" name="username" size="40" /></td>
        </tr>
        <tr>
          <td>Password:</td>
          <td><input type="password" name="password" size="40" /></td>
        </tr>
        <tr>
          <td colspan="2"><input type="submit" name="submit" value="Submit" /></td>
        </tr>
      </table>
    </form>

Add Valid User Check

We need something that provides enforcement for the authentication mechanism -- a global mechanism that prevents users who have not passed authentication from reaching any pages except the login page. This is generally done via an auto action/method (prior to Catalyst v5.66, this sort of thing would go in MyApp.pm, but starting in v5.66, the preferred location is lib/MyApp/Controller/Root.pm).

Edit the existing lib/MyApp/Controller/Root.pm class file and insert the following method:

    =head2 auto
    
    Check if there is a user and, if not, forward to login page
    
    =cut
    
    # Note that 'auto' runs after 'begin' but before your actions and that
    # 'auto' "chain" (all from application path to most specific class are run)
    sub auto : Private {
        my ($self, $c) = @_;
    
        # Allow unauthenticated users to reach the login page
        if ($c->request->path =~ /login/) {
            return 1;
        }
    
        # If a user doesn't exist, force login
        if (!$c->user_exists) {
            # Dump a log message to the development server debug output
            $c->log->debug('***Root::auto User not found, forwarding to /login');
            # Redirect the user to the login page
            $c->response->redirect($c->uri_for('/login'));
            # Return 0 to cancel 'post-auto' processing and prevent use of application
            return 0;
        }
    
        # User found, so return 1 to continue with processing after this 'auto'
        return 1;
    }

Note: Catalyst provides a number of different types of actions, such as Local, Regex, and Private. You should refer to Catalyst::Manual::Intro for a more detailed explanation, but the following bullet points provide a quick introduction:

The majority of application use Local actions for items that respond to user requests and Private actions for those that do not directly respond to user input.
There are five types of Private actions: begin, end, default, index, and auto.
Unlike the other private Private actions where only a single method is called for each request, every auto action along the chain of namespaces will be called.

By placing the authentication enforcement code inside the auto method of lib/MyApp/Controller/Root.pm (or lib/MyApp.pm), it will be called for every request that is received by the entire application.

Displaying Content Only to Authenticated Users

Let's say you want to provide some information on the login page that changes depending on whether the user has authenticated yet. To do this, open root/src/login.tt2 in your editor and add the following lines to the bottom of the file:

    <p>
    [%
       # This code illustrates how certain parts of the TT 
       # template will only be shown to users who have logged in
    %]
    [% IF Catalyst.user %]
        Please Note: You are already logged in as '[% Catalyst.user.username %]'.
        You can <a href="[% Catalyst.uri_for('/logout') %]">logout</a> here.
    [% ELSE %]
        You need to log in to use this application.
    [% END %]
    [%#
       Note that this whole block is a comment because the "#" appears
       immediate after the "[%" (with no spaces in between).  Although it 
       can be a handy way to temporarily "comment out" a whole block of 
       TT code, it's probably a little too subtle for use in "normal" 
       comments.
    %]

Although most of the code is comments, the middle few lines provide a "you are already logged in" reminder if the user returns to the login page after they have already authenticated. For users who have not yet authenticated, a "You need to log in..." message is displayed (note the use of an IF-THEN-ELSE construct in TT).

Try Out Authentication

Press Ctrl-C to kill the previous server instance (if it's still running) and restart it:

    $ script/myapp_server.pl

IMPORTANT NOTE: If you happen to be using Internet Explorer, you may need to use the command script/myapp_server.pl -k to enable the keepalive feature in the development server. Otherwise, the HTTP redirect on successful login may not work correctly with IE (it seems to work without -k if you are running the web browser and development server on the same machine). If you are using browser a browser other than IE, it should work either way. If you want to make keepalive the default, you can edit script/myapp_server.pl and change the initialization value for $keepalive to 1. (You will need to do this every time you create a new Catalyst application or rebuild the myapp_server.pl script.)

Now trying going to http://localhost:3000/books/list and you should be redirected to the login page, hitting Shift+Reload if necessary (the "You are already logged in" message should not appear -- if it does, click the logout button and try again). Note the ***Root::auto User not found... debug message in the development server output. Enter username test01 and password mypass, and you should be taken to the Book List page.

Open root/src/books/list.tt2 and add the following lines to the bottom:

    <p>
      <a href="[% Catalyst.uri_for('/login') %]">Login</a>
      <a href="[% Catalyst.uri_for('form_create') %]">Create</a>
    </p>

Reload your browser and you should now see a "Login" link at the bottom of the page (as mentioned earlier, you can update template files without reloading the development server). Click this link to return to the login page. This time you should see the "You are already logged in" message.

Finally, click the You can logout here link on the /login page. You should stay at the login page, but the message should change to "You need to log in to use this application."

USING PASSWORD HASHES

In this section we increase the security of our system by converting from cleartext passwords to SHA-1 password hashes.

Note: This section is optional. You can skip it and the rest of the tutorial will function normally.

Note that even with the techniques shown in this section, the browser still transmits the passwords in cleartext to your application. We are just avoiding the storage of cleartext passwords in the database by using a SHA-1 hash. If you are concerned about cleartext passwords between the browser and your application, consider using SSL/TLS, made easy with the Catalyst plugin Catalyst::Plugin:RequireSSL.

Get a SHA-1 Hash for the Password

Catalyst uses the Digest module to support a variety of hashing algorithms. Here we will use SHA-1 (SHA = Secure Hash Algorithm). First, we should compute the SHA-1 hash for the "mypass" password we are using. The following command-line Perl script provides a "quick and dirty" way to do this:

    $ perl -MDigest::SHA -e 'print Digest::SHA::sha1_hex("mypass"), "\n"'
    e727d1464ae12436e899a726da5b2f11d8381b26
    $

Switch to SHA-1 Password Hashes in the Database

Next, we need to change the password column of our users table to store this hash value vs. the existing cleartext password. Open myapp03.sql in your editor and enter:

    --
    -- Convert passwords to SHA-1 hashes
    --
    UPDATE users SET password = 'e727d1464ae12436e899a726da5b2f11d8381b26' WHERE id = 1;
    UPDATE users SET password = 'e727d1464ae12436e899a726da5b2f11d8381b26' WHERE id = 2;
    UPDATE users SET password = 'e727d1464ae12436e899a726da5b2f11d8381b26' WHERE id = 3;

Then use the following command to update the SQLite database:

    $ sqlite3 myapp.db < myapp03.sql

Note: We are using SHA-1 hashes here, but many other hashing algorithms are supported. See Digest for more information.

Enable SHA-1 Hash Passwords in `Catalyst::Plugin::Authentication::Store::DBIC`

Edit myapp.yml and update it to match (the password_type and password_hash_type are new, everything else is the same):

    ---
    name: MyApp
    authentication:
        dbic:
            # Note this first definition would be the same as setting
            # __PACKAGE__->config->{authentication}->{dbic}->{user_class} = 'MyAppDB::User'
            # in lib/MyApp.pm (IOW, each hash key becomes a "name:" in the YAML file).
            #
            # This is the model object created by Catalyst::Model::DBIC from your
            # schema (you created 'MyAppDB::User' but as the Catalyst startup
            # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::User').
            # NOTE: Omit 'MyAppDB::Model' to avoid a component lookup issue in Catalyst 5.66
            user_class: MyAppDB::User
            # This is the name of the field in your 'users' table that contains the user's name
            user_field: username
            # This is the name of the field in your 'users' table that contains the password
            password_field: password
            # Other options can go here for hashed passwords
            # Enabled hashed passwords
            password_type: hashed
            # Use the SHA-1 hashing algorithm
            password_hash_type: SHA-1

Try Out the Hashed Passwords

Press Ctrl-C to kill the previous server instance (if it's still running) and restart it:

    $ script/myapp_server.pl

You should now be able to go to http://localhost:3000/books/list and login as before. When done, click the "Logout" link on the login page (or point your browser at http://localhost:3000/logout).

AUTHOR

Kennedy Clark, hkclark@gmail.com

Please report any errors, issues or suggestions to the author.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

Version: .94

To install Catalyst::Runtime, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Catalyst::Runtime

CPAN shell

perl -MCPAN -e shell
install Catalyst::Runtime

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

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