Add rate-limit of TOTP authentication attempts at controller level (#28801)

spec/controllers/auth/sessions_controller_spec.rb

@@ -262,6 +262,26 @@ RSpec.describe Auth::SessionsController do
           end
         end
 
+        context 'when repeatedly using an invalid TOTP code before using a valid code' do
+          before do
+            stub_const('Auth::SessionsController::MAX_2FA_ATTEMPTS_PER_HOUR', 2)
+          end
+
+          it 'does not log the user in' do
+            # Travel to the beginning of an hour to avoid crossing rate-limit buckets
+            travel_to '2023-12-20T10:00:00Z'
+
+            Auth::SessionsController::MAX_2FA_ATTEMPTS_PER_HOUR.times do
+              post :create, params: { user: { otp_attempt: '1234' } }, session: { attempt_user_id: user.id, attempt_user_updated_at: user.updated_at.to_s }
+              expect(controller.current_user).to be_nil
+            end
+
+            post :create, params: { user: { otp_attempt: user.current_otp } }, session: { attempt_user_id: user.id, attempt_user_updated_at: user.updated_at.to_s }
+            expect(controller.current_user).to be_nil
+            expect(flash[:alert]).to match I18n.t('users.rate_limited')
+          end
+        end
+
         context 'when using a valid OTP' do
           before do
             post :create, params: { user: { otp_attempt: user.current_otp } }, session: { attempt_user_id: user.id, attempt_user_updated_at: user.updated_at.to_s }