Retry 401 errors on replies fetching (#28788)

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

app/helpers/jsonld_helper.rb

@@ -157,7 +157,7 @@ module JsonLdHelper
     end
   end
 
-  def fetch_resource(uri, id, on_behalf_of = nil)
+  def fetch_resource(uri, id, on_behalf_of = nil, request_options: {})
     unless id
       json = fetch_resource_without_id_validation(uri, on_behalf_of)
 
@@ -166,14 +166,14 @@ module JsonLdHelper
       uri = json['id']
     end
 
-    json = fetch_resource_without_id_validation(uri, on_behalf_of)
+    json = fetch_resource_without_id_validation(uri, on_behalf_of, request_options: request_options)
     json.present? && json['id'] == uri ? json : nil
   end
 
-  def fetch_resource_without_id_validation(uri, on_behalf_of = nil, raise_on_temporary_error = false)
+  def fetch_resource_without_id_validation(uri, on_behalf_of = nil, raise_on_temporary_error = false, request_options: {})
     on_behalf_of ||= Account.representative
 
-    build_request(uri, on_behalf_of).perform do |response|
+    build_request(uri, on_behalf_of, options: request_options).perform do |response|
       raise Mastodon::UnexpectedResponseError, response unless response_successful?(response) || response_error_unsalvageable?(response) || !raise_on_temporary_error
 
       body_to_json(response.body_with_limit) if response.code == 200
@@ -206,8 +206,8 @@ module JsonLdHelper
     response.code == 501 || ((400...500).cover?(response.code) && ![401, 408, 429].include?(response.code))
   end
 
-  def build_request(uri, on_behalf_of = nil)
+  def build_request(uri, on_behalf_of = nil, options: {})
-    Request.new(:get, uri).tap do |request|
+    Request.new(:get, uri, **options).tap do |request|
       request.on_behalf_of(on_behalf_of) if on_behalf_of
       request.add_headers('Accept' => 'application/activity+json, application/ld+json')
     end

app/services/activitypub/fetch_replies_service.rb

@@ -36,7 +36,21 @@ class ActivityPub::FetchRepliesService < BaseService
     return collection_or_uri if collection_or_uri.is_a?(Hash)
     return unless @allow_synchronous_requests
     return if invalid_origin?(collection_or_uri)
-    fetch_resource_without_id_validation(collection_or_uri, nil, true)
+
+    # NOTE: For backward compatibility reasons, Mastodon signs outgoing
+    # queries incorrectly by default.
+    #
+    # While this is relevant for all URLs with query strings, this is
+    # the only code path where this happens in practice.
+    #
+    # Therefore, retry with correct signatures if this fails.
+    begin
+      fetch_resource_without_id_validation(collection_or_uri, nil, true)
+    rescue Mastodon::UnexpectedResponseError => e
+      raise unless e.response && e.response.code == 401 && Addressable::URI.parse(collection_or_uri).query.present?
+
+      fetch_resource_without_id_validation(collection_or_uri, nil, true, request_options: { with_query_string: true })
+    end
   end
 
   def filtered_replies