Add Discourse SSO to allow login into Discourse via Foodsoft

app/controllers/application_controller.rb

@@ -142,15 +142,19 @@ class ApplicationController < ActionController::Base
   #     end
   #
   def require_plugin_enabled(plugin)
-    unless plugin.enabled?
+    redirect_to_root_with_feature_disabled_alert unless plugin.enabled?
-      redirect_to root_path, alert: I18n.t('application.controller.error_feature_disabled')
   end
+
+  def require_config_enabled(config)
+    redirect_to_root_with_feature_disabled_alert unless FoodsoftConfig[config]
   end
 
   def require_config_disabled(config)
-    if FoodsoftConfig[config]
+    redirect_to_root_with_feature_disabled_alert if FoodsoftConfig[config]
-      redirect_to root_path, alert: I18n.t('application.controller.error_feature_disabled')
   end
+
+  def redirect_to_root_with_feature_disabled_alert
+    redirect_to root_path, alert: I18n.t('application.controller.error_feature_disabled')
   end
 
   # Redirect to the login page, used in authenticate, plugins can override this.

plugins/discourse/README.md

@@ -1,8 +1,8 @@
 FoodsoftDiscourse
 =================
 
-This plugin adds the possibility to log in via Discourse. A new button is added
+This plugin adds the possibility to log in via Discourse or act as and SSO
-to the login screen.
+provider for Discourse. A new button is added to the login screen if enabled.
 
 This plugin is enabled by default in foodsoft, so you don't need to do anything
 to install it. If you still want to, for example when it has been disabled,
@@ -13,10 +13,14 @@ gem 'foodsoft_discourse', path: 'plugins/foodsoft_discourse'
 ```
 
 This plugin introduces the foodcoop config option `discourse_url`, which takes
-the URL fo the Discourse installation (e.g. `https://forum.example.com`) and the
+the URL for the Discourse installation (e.g. `https://forum.example.com`) and
-config option `discourse_sso_secret`, which must be set to the same values as
+the config option `discourse_sso_secret`, which must be set to the same values
-configured in the `sso secret` setting of the Discourse installation. The plugin
+as configured in the `sso secret` setting of the Discourse installation. The
-will be disabled if not both config options are set.
+plugin will be disabled if not both config options are set.
+
+If `discourse_sso` is set to `true` Foodsoft will act as an SSO provider for
+Discourse. The `sso url` for Discourse is `/discourse/sso` relative to root url
+of Foodsoft (e.g. `https://foodsoft.example.com/f/discourse/sso`).
 
 This plugin is part of the foodsoft package and uses the GPL-3 license (see
 foodsoft's LICENSE for the full license text).

plugins/discourse/app/controllers/discourse_controller.rb

@@ -1,49 +1,25 @@
 class DiscourseController < ApplicationController
 
   before_filter -> { require_plugin_enabled FoodsoftDiscourse }
-  skip_before_filter :authenticate
 
-  def initiate
+  protected
-    discourse_url = FoodsoftConfig[:discourse_url]
 
-    nonce = SecureRandom.hex()
+  def valid_signature?
-    return_sso_url = url_for(action: :callback, only_path: false)
+    return false if params[:sso].blank? || params[:sig].blank?
-    payload = "nonce=#{nonce}&return_sso_url=#{return_sso_url}"
+    get_hmac_hex_string(params[:sso]) == params[:sig]
-    base64_payload = Base64.encode64 payload
+  end
-    sso = URI.escape base64_payload
+
+  def redirect_to_with_payload(url, payload)
+    base64_payload = Base64.encode64 payload.to_query
+    sso = CGI::escape base64_payload
     sig = get_hmac_hex_string base64_payload
-
+    redirect_to "#{url}#{url.include?('?') ? '&' : '?'}sso=#{sso}&sig=#{sig}"
-    session[:discourse_sso_nonce] = nonce
-    redirect_to "#{discourse_url}/session/sso_provider?sso=#{sso}&sig=#{sig}"
   end
 
-  def callback
+  def parse_payload
-    raise I18n.t('discourse.callback.invalid_signature') if get_hmac_hex_string(params[:sso]) != params[:sig]
+    payload = Rack::Utils.parse_query Base64.decode64(params[:sso])
-
+    payload.symbolize_keys!
-    info = Rack::Utils.parse_query(Base64.decode64(params[:sso]))
-    info.symbolize_keys!
-
-    raise I18n.t('discourse.callback.invalid_nonce') if info[:nonce] != session[:discourse_sso_nonce]
-    session[:discourse_sso_nonce] = nil
-
-    id = info[:external_id].to_i
-    user = User.find_or_initialize_by(id: id) do |user|
-      user.id = id
-      user.password = SecureRandom.random_bytes(25)
   end
-    user.nick = info[:username]
-    user.email = info[:email]
-    user.first_name = info[:name]
-    user.last_name = ''
-    user.last_login = Time.now
-    user.save!
-
-    login_and_redirect_to_return_to user, :notice => I18n.t('discourse.callback.logged_in')
-  rescue => error
-    redirect_to login_url, :alert => error.to_s
-  end
-
-  private
 
   def get_hmac_hex_string payload
     discourse_sso_secret = FoodsoftConfig[:discourse_sso_secret]

plugins/discourse/app/controllers/discourse_login_controller.rb

@@ -0,0 +1,43 @@
+class DiscourseLoginController < DiscourseController
+
+  before_filter -> { require_config_disabled :discourse_sso }
+  skip_before_filter :authenticate
+
+  def initiate
+    discourse_url = FoodsoftConfig[:discourse_url]
+
+    nonce = SecureRandom.hex()
+    return_sso_url = url_for(action: :callback, only_path: false)
+
+    session[:discourse_sso_nonce] = nonce
+    redirect_to_with_payload "#{discourse_url}/session/sso_provider",
+      nonce: nonce,
+      return_sso_url: return_sso_url
+  end
+
+  def callback
+    raise I18n.t('discourse.callback.invalid_signature') unless valid_signature?
+
+    payload = parse_payload
+
+    raise I18n.t('discourse.callback.invalid_nonce') if payload[:nonce] != session[:discourse_sso_nonce]
+    session[:discourse_sso_nonce] = nil
+
+    id = payload[:external_id].to_i
+    user = User.find_or_initialize_by(id: id) do |user|
+      user.id = id
+      user.password = SecureRandom.random_bytes(25)
+    end
+    user.nick = payload[:username]
+    user.email = payload[:email]
+    user.first_name = payload[:name]
+    user.last_name = ''
+    user.last_login = Time.now
+    user.save!
+
+    login_and_redirect_to_return_to user, notice: I18n.t('discourse.callback.logged_in')
+  rescue => error
+    redirect_to login_url, alert: error.to_s
+  end
+
+end

plugins/discourse/app/controllers/discourse_sso_controller.rb

@@ -0,0 +1,25 @@
+class DiscourseSsoController < DiscourseController
+
+  before_filter -> { require_config_enabled :discourse_sso }
+
+  def sso
+    raise I18n.t('discourse.sso.invalid_signature') unless valid_signature?
+
+    payload = parse_payload
+    nonce = payload[:nonce]
+    return_sso_url = payload[:return_sso_url] || "#{discourse_url}/session/sso_login"
+
+    raise I18n.t('discourse.sso.nonce_missing') if nonce.blank?
+
+    redirect_to_with_payload return_sso_url,
+      nonce: nonce,
+      email: current_user.email,
+      require_activation: true,
+      external_id: "#{FoodsoftConfig.scope}/#{current_user.id}",
+      username: current_user.nick,
+      name: current_user.name
+  rescue => error
+    redirect_to root_url, alert: error.to_s
+  end
+
+end

plugins/discourse/app/overrides/sessions/new/insert_link.html.haml.deface

@@ -1,5 +1,5 @@
 / insert_after 'noscript'
-- if FoodsoftDiscourse.enabled?
+- if FoodsoftDiscourse.enabled? && !FoodsoftConfig[:discourse_sso]
   .center
     = link_to t('.discourse_login'), discourse_initiate_path, class: 'btn btn-primary'
   %hr

plugins/discourse/config/routes.rb

@@ -2,8 +2,9 @@ Rails.application.routes.draw do
 
   scope '/:foodcoop' do
 
-    get '/discourse/callback' => 'discourse#callback'
+    get '/discourse/callback' => 'discourse_login#callback'
-    get '/discourse/initiate' => 'discourse#initiate'
+    get '/discourse/initiate' => 'discourse_login#initiate'
+    get '/discourse/sso' => 'discourse_sso#sso'
 
   end
 

plugins/discourse/lib/foodsoft_discourse/redirect_to_login.rb

@@ -7,8 +7,11 @@ module FoodsoftDiscourse
         alias orig_redirect_to_login redirect_to_login
 
         def redirect_to_login(options={})
-          return orig_redirect_to_login(options) unless FoodsoftDiscourse.enabled?
+          if FoodsoftDiscourse.enabled? && !FoodsoftConfig[:discourse_sso]
             redirect_to discourse_initiate_path
+          else
+            orig_redirect_to_login(options)
+          end
         end
 
       end