Move signature verification stoplight to the requests themselves (mastodon#10813)

* Move signature verification stoplight to the requests themselves

This avoids blocking messages from known keys for 5 minutes when only one fails…

* Put the stoplight on the actual client IP, not a potential reverse proxy

Author: ClearlyClaire

app/controllers/concerns/signature_verification.rb

@@ -43,13 +43,7 @@ def signed_request_account
       return
     end
 
-    account_stoplight = Stoplight("source:#{request.ip}") { account_from_key_id(signature_params['keyId']) }
-      .with_fallback { nil }
-      .with_threshold(1)
-      .with_cool_off_time(5.minutes.seconds)
-      .with_error_handler { |error, handle| error.is_a?(HTTP::Error) ? handle.call(error) : raise(error) }
-
-    account = account_stoplight.run
+    account = account_from_key_id(signature_params['keyId'])
 
     if account.nil?
       @signature_verification_failure_reason = "Public key not found for key #{signature_params['keyId']}"
@@ -62,13 +56,7 @@ def signed_request_account
 
     return account unless verify_signature(account, signature, compare_signed_string).nil?
 
-    account_stoplight = Stoplight("source:#{request.ip}") { account.possibly_stale? ? account.refresh! : account_refresh_key(account) }
-      .with_fallback { nil }
-      .with_threshold(1)
-      .with_cool_off_time(5.minutes.seconds)
-      .with_error_handler { |error, handle| error.is_a?(HTTP::Error) ? handle.call(error) : raise(error) }
-
-    account = account_stoplight.run
+    account = stoplight_wrap_request { account.possibly_stale? ? account.refresh! : account_refresh_key(account) }
 
     if account.nil?
       @signature_verification_failure_reason = "Public key not found for key #{signature_params['keyId']}"
@@ -136,14 +124,23 @@ def incompatible_signature?(signature_params)
 
   def account_from_key_id(key_id)
     if key_id.start_with?('acct:')
-      ResolveAccountService.new.call(key_id.gsub(/\Aacct:/, ''))
+      stoplight_wrap_request { ResolveAccountService.new.call(key_id.gsub(/\Aacct:/, '')) }
     elsif !ActivityPub::TagManager.instance.local_uri?(key_id)
       account   = ActivityPub::TagManager.instance.uri_to_resource(key_id, Account)
-      account ||= ActivityPub::FetchRemoteKeyService.new.call(key_id, id: false)
+      account ||= stoplight_wrap_request { ActivityPub::FetchRemoteKeyService.new.call(key_id, id: false) }
       account
     end
   end
 
+  def stoplight_wrap_request(&block)
+    Stoplight("source:#{request.remote_ip}", &block)
+      .with_fallback { nil }
+      .with_threshold(1)
+      .with_cool_off_time(5.minutes.seconds)
+      .with_error_handler { |error, handle| error.is_a?(HTTP::Error) ? handle.call(error) : raise(error) }
+      .run
+  end
+
   def account_refresh_key(account)
     return if account.local? || !account.activitypub?
     ActivityPub::FetchRemoteAccountService.new.call(account.uri, only_key: true)