object containment: handle all cases where ID is invalid (missing, nil, non-string)

lib/pleroma/object/containment.ex

@@ -51,9 +51,7 @@ def contain_origin(id, %{"actor" => _actor} = params) do
   def contain_origin(id, %{"attributedTo" => actor} = params),
     do: contain_origin(id, Map.put(params, "actor", actor))
 
-  def contain_origin_from_id(_id, %{"id" => nil}), do: :error
+  def contain_origin_from_id(id, %{"id" => other_id} = _params) when is_binary(other_id) do
-
-  def contain_origin_from_id(id, %{"id" => other_id} = _params) do
     id_uri = URI.parse(id)
     other_uri = URI.parse(other_id)
 
@@ -64,6 +62,8 @@ def contain_origin_from_id(id, %{"id" => other_id} = _params) do
     end
   end
 
+  def contain_origin_from_id(_id, _data), do: :error
+
   def contain_child(%{"object" => %{"id" => id, "attributedTo" => _} = object}),
     do: contain_origin(id, object)
 

test/object/containment_test.exs

@@ -67,6 +67,20 @@ test "users cannot be collided through fake direction spoofing attempts" do
              end) =~
                "[error] Could not decode user at fetch https://n1u.moe/users/rye, {:error, :error}"
     end
+
+    test "contain_origin_from_id() gracefully handles cases where no ID is present" do
+      data = %{
+        "type" => "Create",
+        "object" => %{
+          "id" => "http://example.net/~alyssa/activities/1234",
+          "attributedTo" => "http://example.org/~alyssa"
+        },
+        "actor" => "http://example.com/~bob"
+      }
+
+      :error =
+        Containment.contain_origin_from_id("http://example.net/~alyssa/activities/1234", data)
+    end
   end
 
   describe "containment of children" do