oa-casport-rails3

So you want to authenticate with CASPORT in a Rails 3 app eh?

This simple site will show you how easy it is to use the oa-casport gem for CASPORT authentication.

Install the oa-casport Gem

First start by adding the following gem to your Gemfile:

gem 'oa-casport'

Then update your gems with Bundler:

$ bundle

Configure oa-casport and Initialize

Next you'll need to load oa-casport into your Rails application as a Rack middleware application via an initializer.

#config/initializers/omniauth.rb
Rails.application.config.middleware.use OmniAuth::Builder do
  provider :casport, {
    :setup       => true,
    :cas_server  => 'http://cas.slkdemos.com/users/',
    :ssl_ca_file => '/path/to/your/server/Apache_bundle_file.crt',
    :pem_cert    => '/path/to/your/server/pem_certificate_file.pem'
  }
end

Setup the OmniAuth Infrastructure

In order to use custom OmniAuth strategies (like oa-casport) you'll need to create a User model with at least two attributes provider and uid. You can add in any extra fields that the CASPORT server returns for users which you might want to store in your database as well. Here's an example using the Rails model generator along with all fields provided by the sample CASPORT server:

$ rails g model user provider:string uid:string email:string first_name:string last_name:string phone:string cell:string address:string address2:string city:string state:string country:string
$ rake db:migrate

After you've created your user model you'll need to create a sessions controller for OmniAuth routes:

$ rails g controller sessions

Lastly, we need to map some routes for OmniAuth:

#config/routes.rb
match '/auth/:provider/setup', :to => 'sessions#setup'
match '/auth/:provider/callback', :to => 'sessions#create'
match '/signout' => 'sessions#destroy', :as => :signout

Configure Sessions for oa-casport

Next we need to create the sessions controller to handle user authentication via CASPORT.

#app/controllers/sessions_controller.rb
class SessionsController < ApplicationController

  def setup
    # replace request.env['SSL_CLIENT_S_DN'] with your web server's user DN string from SSL
    request.env['omniauth.strategy'].options[:uid] = request.env['SSL_CLIENT_S_DN']
    render :text => 'Setup complete', :status => 404
  end
  
  def create
    auth_hash = request.env['omniauth.auth']
    user = User.find_by_provider_and_uid(auth_hash['provider'], auth_hash['uid']) || User.create_with_omniauth(auth_hash)
    session[:user_id] = user.id
    redirect_to root_url, :notice => 'Thanks for logging in with CASPORT'
  end
  
  def destroy
    session[:user_id] = nil
    redirect_to root_url, :notice => 'You have signed out'
  end

end

Creating the User Model

Since we've received data back from CASPORT now it's time to store that data to our database. Add the following to the user model:

#app/models/user.rb
class User < ActiveRecord::Base
  attr_protected :id, :uid, :provider

  private
  def self.create_with_omniauth(auth_hash)
    create! do |user|
      user.provider   = auth_hash['provider']
      user.uid        = auth_hash['uid']
      user.email      = auth_hash['user_info']['email']
      user.first_name = auth_hash['extra']['user_hash']['first_name']
      user.last_name  = auth_hash['extra']['user_hash']['last_name']
      user.phone      = auth_hash['extra']['user_hash']['phone']
      user.cell       = auth_hash['extra']['user_hash']['cell']
      user.address    = auth_hash['extra']['user_hash']['address']
      user.address2   = auth_hash['extra']['user_hash']['address2']
      user.city       = auth_hash['extra']['user_hash']['city']
      user.state      = auth_hash['extra']['user_hash']['state']
      user.country    = auth_hash['extra']['user_hash']['country']
    end
  end

end

Configure User Login

Now that you have the ability to get a user's details from CASPORT and have saved them to your database, let's setup a current_user like most Rails applications:

#app/controllers/application_controller.rb
before_filter :current_user
helper_method :current_user

private
def current_user
  @current_user ||= User.find(session[:user_id]) if session[:user_id]
  #To force automatic login uncomment the following line:
  redirect_to '/auth/casport' unless @current_user or (params[:controller] == 'sessions' && params[:provider] == 'casport')
end