feat: configurable trusted proxies for web requests

config/initializers/trusted_proxies.rb

@@ -1,15 +1,10 @@
 # frozen_string_literal: true
 
-module Rack
-  class Request
-
-    module Helpers
-
-      def trusted_proxy?(ip)
-        ip =~ /^127\.0\.0\.1$|^localhost$|^unix$$/i
-      end
-
-    end
-
+Rack::Request.ip_filter = lambda { |ip|
+  if Postal::Config.postal.trusted_proxies.any? { |net| net.include?(ip) } ||
+     ip.match(/\A127\.0\.0\.1\Z|\A::1\Z|\Afd[0-9a-f]{2}:.+|\Alocalhost\Z|\Aunix\Z|\Aunix:/i)
+    true
+  else
+    false
   end
-end
+}