Refactor registration authorization logic

app/controllers/api/v1/accounts_controller.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class Api::V1::AccountsController < Api::BaseController
+  include RegistrationHelper
+
   before_action -> { authorize_if_got_token! :read, :'read:accounts' }, except: [:create, :follow, :unfollow, :remove_from_followers, :block, :unblock, :mute, :unmute]
   before_action -> { doorkeeper_authorize! :follow, :write, :'write:follows' }, only: [:follow, :unfollow, :remove_from_followers]
   before_action -> { doorkeeper_authorize! :follow, :write, :'write:mutes' }, only: [:mute, :unmute]
@@ -94,14 +96,6 @@ class Api::V1::AccountsController < Api::BaseController
   end
 
   def check_enabled_registrations
-    forbidden if single_user_mode? || omniauth_only? || !allowed_registrations?
+    forbidden unless allowed_registration?(request.remote_ip, nil)
-  end
-
-  def allowed_registrations?
-    Setting.registrations_mode != 'none'
-  end
-
-  def omniauth_only?
-    ENV['OMNIAUTH_ONLY'] == 'true'
   end
 end

app/controllers/auth/registrations_controller.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 class Auth::RegistrationsController < Devise::RegistrationsController
+  include RegistrationHelper
   include RegistrationSpamConcern
 
   layout :determine_layout
@@ -82,19 +83,7 @@ class Auth::RegistrationsController < Devise::RegistrationsController
   end
 
   def check_enabled_registrations
-    redirect_to root_path if single_user_mode? || omniauth_only? || !allowed_registrations? || ip_blocked?
+    redirect_to root_path unless allowed_registration?(request.remote_ip, @invite)
-  end
-
-  def allowed_registrations?
-    Setting.registrations_mode != 'none' || @invite&.valid_for_use?
-  end
-
-  def omniauth_only?
-    ENV['OMNIAUTH_ONLY'] == 'true'
-  end
-
-  def ip_blocked?
-    IpBlock.where(severity: :sign_up_block).where('ip >>= ?', request.remote_ip.to_s).exists?
   end
 
   def invite_code

app/helpers/registration_helper.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module RegistrationHelper
+  extend ActiveSupport::Concern
+
+  def allowed_registration?(remote_ip, invite)
+    !Rails.configuration.x.single_user_mode && !omniauth_only? && (registrations_open? || invite&.valid_for_use?) && !ip_blocked?(remote_ip)
+  end
+
+  def registrations_open?
+    Setting.registrations_mode != 'none'
+  end
+
+  def omniauth_only?
+    ENV['OMNIAUTH_ONLY'] == 'true'
+  end
+
+  def ip_blocked?(remote_ip)
+    IpBlock.where(severity: :sign_up_block).exists?(['ip >>= ?', remote_ip.to_s])
+  end
+end

app/services/app_sign_up_service.rb

@@ -1,12 +1,14 @@
 # frozen_string_literal: true
 
 class AppSignUpService < BaseService
+  include RegistrationHelper
+
   def call(app, remote_ip, params)
     @app       = app
     @remote_ip = remote_ip
     @params    = params
 
-    raise Mastodon::NotPermittedError unless allowed_registrations?
+    raise Mastodon::NotPermittedError unless allowed_registration?(remote_ip, nil)
 
     ApplicationRecord.transaction do
       create_user!
@@ -45,24 +47,4 @@ class AppSignUpService < BaseService
   def invite_request_params
     { text: @params[:reason] }
   end
-
-  def allowed_registrations?
-    registrations_open? && !single_user_mode? && !omniauth_only? && !ip_blocked?
-  end
-
-  def registrations_open?
-    Setting.registrations_mode != 'none'
-  end
-
-  def single_user_mode?
-    Rails.configuration.x.single_user_mode
-  end
-
-  def omniauth_only?
-    ENV['OMNIAUTH_ONLY'] == 'true'
-  end
-
-  def ip_blocked?
-    IpBlock.where(severity: :sign_up_block).where('ip >>= ?', @remote_ip.to_s).exists?
-  end
 end