redirect to discovery page for unauthenticated deep links

refs #CNVS-2174

found the bit in the authorization sequence where
saml login was being initiated without checking
for a discovery url.  Fixed that, and also wrote
some unit tests around it.

ended up having to alter specs a bit to deal
with the extensions added by the
canvas_zendesk_plugin

TEST PLAN:
1) select an account that is authenticated with SAML
2) without logging in, attempt to hit a 'deep
  link' on that domain with the browser (any url
  that isn't the login page would be fine, as long
  as it's something you must be logged in to access)
3) you should be redirected to the SAML discovery page

Change-Id: Id9c21650d8c053178d4d40ff064051af79c5eb2f
Reviewed-on: https://gerrit.instructure.com/16355
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Ethan Vizitei <ethan@12spokes.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>
QA-Review: Clare Hetherington <clare@instructure.com>

lib/authentication_methods.rb

@@ -228,13 +228,19 @@ module AuthenticationMethods
 
   def initiate_delegated_login(current_host=nil)
     is_delegated = @domain_root_account.delegated_authentication? && !params[:canvas_login]
-    is_cas = @domain_root_account.cas_authentication? && is_delegated
-    is_saml = @domain_root_account.saml_authentication? && is_delegated
+    is_cas = is_delegated && @domain_root_account.cas_authentication?
+    is_saml = is_delegated && @domain_root_account.saml_authentication?
     if is_cas
       initiate_cas_login
       return true
     elsif is_saml
+
+      if @domain_root_account.auth_discovery_url
+        redirect_to @domain_root_account.auth_discovery_url
+      else
         initiate_saml_login(current_host)
+      end
+
       return true
     end
     false

spec/integration/pseudonym_sessions_controller_spec.rb

@@ -115,6 +115,18 @@ describe PseudonymSessionsController do
     end
   end
 
+  context "SAML" do
+    it 'redirects to the discovery page when hitting a deep link while unauthenticated' do
+      account = account_with_saml( :account => Account.default )
+      discovery_url = 'http://discovery-url.example.com'
+      account.auth_discovery_url = discovery_url
+      account.save!
+
+      get account_account_authorization_configs_url(account)
+      redirect_until(discovery_url)
+    end
+  end
+
   it "should redirect back for jobs controller" do
     user_with_pseudonym(:password => 'qwerty', :active_all => 1)
     Account.site_admin.add_user(@user)

spec/lib/authentication_methods_spec.rb

@@ -0,0 +1,120 @@
+require File.expand_path('../spec_helper', File.dirname(__FILE__))
+
+
+describe AuthenticationMethods do
+
+  describe '#initiate_delegated_login' do
+    let(:request) { stub(:host_with_port => '' ) }
+    let(:controller) { Spec::MockController.new(domain_root_account, request) }
+
+    describe 'when auth is not delegated' do
+      let(:domain_root_account) { stub(:delegated_authentication? => false) }
+
+      it 'returns false' do
+        controller.initiate_delegated_login.should be_false
+      end
+
+      it 'does not redirect anywhere' do
+        controller.initiate_delegated_login
+        controller.redirects.should == []
+      end
+    end
+
+    describe 'when auth is CAS' do
+      let(:domain_root_account) do
+        stub(
+          :delegated_authentication? => true,
+          :cas_authentication? => true,
+          :saml_authentication? => false,
+          :account_authorization_config => stub(:auth_base => 'base_url')
+        )
+      end
+
+      it 'returns true' do
+        controller.initiate_delegated_login.should be_true
+      end
+
+      it 'redirects to CAS client url' do
+        client = stub(:add_service_to_login_url => 'cas_login_url')
+        CASClient::Client.stubs(:new => client)
+        controller.initiate_delegated_login
+        controller.redirects.should == ['cas_login_url']
+      end
+
+      it 'can be overriden by passing the canvas_login parameter' do
+        controller = Spec::MockController.new(domain_root_account, request, :canvas_login => true)
+        controller.initiate_delegated_login.should be_false
+        controller.redirects.should == []
+      end
+    end
+
+    describe 'when auth is SAML' do
+      let(:domain_root_account) do
+        stub(
+          :delegated_authentication? => true,
+          :cas_authentication? => false,
+          :saml_authentication? => true,
+          :account_authorization_config => stub(:saml_settings => {}, :debugging? => false),
+          :auth_discovery_url => nil
+        )
+      end
+
+      let(:saml_request) { stub(:generate_request => 'saml_login_url') }
+
+      before do
+        Onelogin::Saml::AuthRequest.stubs(:new => saml_request)
+      end
+
+      it 'returns true' do
+        controller.initiate_delegated_login.should be_true
+      end
+
+      it 'redirects to SAML auth request url' do
+        controller.initiate_delegated_login
+        controller.redirects.should == ['saml_login_url']
+      end
+
+      it 'redirects to the discovery url if there is one' do
+        domain_root_account.stubs(:auth_discovery_url => 'discovery_url')
+        controller.initiate_delegated_login
+        controller.redirects.should == ['discovery_url']
+      end
+
+      it 'can be overriden by passing the canvas_login parameter' do
+        controller = Spec::MockController.new(domain_root_account, request, :canvas_login => true)
+        controller.initiate_delegated_login.should be_false
+        controller.redirects.should == []
+      end
+    end
+  end
+end
+
+class Spec::MockController
+  include AuthenticationMethods
+
+  attr_reader :redirects, :params, :session, :request
+
+  def initialize(root_account, req, params_hash = {})
+    @domain_root_account = root_account
+    @request = req
+    @redirects = []
+    @params = params_hash
+    reset_session
+  end
+
+  def reset_session
+    @session = {}
+  end
+
+  def redirect_to(url)
+    @redirects << url
+  end
+
+  def cas_login_url; ''; end
+
+  def zendesk_delegated_auth_pass_through_url(options)
+    options[:target]
+  end
+
+end
+