From 6f9db37ca3946cdfe792f9a913e333b30b34a68d Mon Sep 17 00:00:00 2001
From: Thomas Citharel <tcit@tcit.fr>
Date: Tue, 10 Aug 2021 20:32:50 +0200
Subject: [PATCH] Fix checking origin from a tombstone

When comparing an activity with their origin, only compare the ID
directly, as Tombstones don't have actors anymore

Signed-off-by: Thomas Citharel <tcit@tcit.fr>
---
 lib/federation/activity_pub/fetcher.ex      |  2 +-
 lib/federation/activity_pub/utils.ex        |  2 ++
 test/federation/activity_pub/utils_test.exs | 10 ++++++++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/federation/activity_pub/fetcher.ex b/lib/federation/activity_pub/fetcher.ex
index 7bac0fee3..71a7cfc1c 100644
--- a/lib/federation/activity_pub/fetcher.ex
+++ b/lib/federation/activity_pub/fetcher.ex
@@ -142,7 +142,7 @@ defmodule Mobilizon.Federation.ActivityPub.Fetcher do
       true
     else
       Sentry.capture_message("Object origin check failed", extra: %{url: url, data: data})
-      Logger.debug("Object origin check failed")
+      Logger.debug("Object origin check failed between #{inspect(url)} and #{inspect(data)}")
       false
     end
   end
diff --git a/lib/federation/activity_pub/utils.ex b/lib/federation/activity_pub/utils.ex
index 7a7af94a1..86252e255 100644
--- a/lib/federation/activity_pub/utils.ex
+++ b/lib/federation/activity_pub/utils.ex
@@ -239,6 +239,8 @@ defmodule Mobilizon.Federation.ActivityPub.Utils do
 
   Takes the actor or attributedTo attributes (considers only the first elem if they're an array)
   """
+  def origin_check?(id, %{"type" => "Tombstone", "id" => tombstone_id}), do: id == tombstone_id
+
   def origin_check?(id, %{"actor" => actor, "attributedTo" => _attributed_to} = params)
       when not is_nil(actor) and actor != "" do
     params = Map.delete(params, "attributedTo")
diff --git a/test/federation/activity_pub/utils_test.exs b/test/federation/activity_pub/utils_test.exs
index d62f00d5e..4aff20089 100644
--- a/test/federation/activity_pub/utils_test.exs
+++ b/test/federation/activity_pub/utils_test.exs
@@ -5,6 +5,7 @@ defmodule Mobilizon.Federation.ActivityPub.UtilsTest do
 
   import Mobilizon.Factory
 
+  alias Mobilizon.Federation.ActivityPub.Utils
   alias Mobilizon.Federation.ActivityStream.Converter
 
   alias Mobilizon.Web.Endpoint
@@ -51,4 +52,13 @@ defmodule Mobilizon.Federation.ActivityPub.UtilsTest do
       assert comment_data["inReplyTo"] == comment.url
     end
   end
+
+  describe "origin_check?" do
+    test "origin_check? with a tombstone" do
+      assert Utils.origin_check?("http://an_uri", %{
+               "type" => "Tombstone",
+               "id" => "http://an_uri"
+             })
+    end
+  end
 end