Merge commit from fork

app/helpers/json_ld_helper.rb

@@ -3,6 +3,8 @@
 module JsonLdHelper
   include ContextHelper
 
+  UNSUPPORTED_JSONLD_KEYWORDS = %w(@graph @included @reverse).freeze
+
   def equals_or_includes?(haystack, needle)
     haystack.is_a?(Array) ? haystack.include?(needle) : haystack == needle
   end
@@ -110,6 +112,16 @@ module JsonLdHelper
     compacted
   end
 
+  def unsupported_jsonld_features?(json)
+    if json.is_a?(Hash)
+      json.any? { |key, value| UNSUPPORTED_JSONLD_KEYWORDS.include?(key) || unsupported_jsonld_features?(value) }
+    elsif json.is_a?(Array)
+      json.any? { |value| unsupported_jsonld_features?(value) }
+    else
+      false
+    end
+  end
+
   # Patches a JSON-LD document to avoid compatibility issues on redistribution
   #
   # Since compacting a JSON-LD document against Mastodon's built-in vocabulary

app/lib/activitypub/linked_data_signature.rb

@@ -12,6 +12,7 @@ class ActivityPub::LinkedDataSignature
 
   def verify_actor!
     return unless @json['signature'].is_a?(Hash)
+    return if unsupported_jsonld_features?(@json)
 
     type        = @json['signature']['type']
     creator_uri = @json['signature']['creator']

app/services/activitypub/process_collection_service.rb

@@ -13,6 +13,10 @@ class ActivityPub::ProcessCollectionService < BaseService
 
     begin
       @json = compact(@json) if @json['signature'].is_a?(Hash)
+      if unsupported_jsonld_features?(@json)
+        Rails.logger.debug { "JSON-LD document for #{value_or_id(@json['actor'])} contains unsupported JSON-LD features" }
+        @json = original_json.without('signature')
+      end
     rescue JSON::LD::JsonLdError => e
       Rails.logger.debug { "Error when compacting JSON-LD document for #{value_or_id(@json['actor'])}: #{e.message}" }
       @json = original_json.without('signature')