Add support for ads.txt redirect

config/locales/server.en.yml

@@ -51,6 +51,7 @@ en:
     adsense_post_bottom_ad_sizes: "Choose your ad size"
     adsense_mobile_post_bottom_ad_size: "Choose your ad size"
     adsense_nth_post_code: "Show an ad after every N posts, where N is this value."
+    adsense_ads_txt_url: "URL of ads.txt file."
 
     amazon_through_trust_level: "Show your ads to users based on trust levels. Users with trust level higher than this value will not see ads."
     amazon_topic_list_top_src_code: "Enter src code to display at topic list top location"

plugin.rb

@@ -176,3 +176,20 @@ and (max-width : 775px) {
 }
 
 CSS
+
+after_initialize do
+  require_dependency 'application_controller'
+  class ::AdstxtController < ::ApplicationController
+    skip_before_action :check_xhr
+
+    def index
+      raise Discourse::NotFound unless SiteSetting.adsense_ads_txt_url.present?
+
+      redirect_to SiteSetting.adsense_ads_txt_url
+    end
+  end
+
+  Discourse::Application.routes.append do
+    get '/ads.txt' => "adstxt#index"
+  end
+end