lib/pleroma/object/fetcher.ex

@@ -317,7 +317,7 @@ def fetch_and_contain_remote_object_from_id(id, is_ap_id) when is_binary(id) do
 
       {:containment, reason} ->
         log_fetch_error(id, reason)
-        {:error, reason}
+        {:error, {:containment, reason}}
 
       {:error, e} ->
         {:error, e}
@@ -330,22 +330,10 @@ def fetch_and_contain_remote_object_from_id(id, is_ap_id) when is_binary(id) do
   def fetch_and_contain_remote_object_from_id(_id, _is_ap_id),
     do: {:error, :invalid_id}
 
-  defp check_crossdomain_redirect(final_host, original_url)
-
   # HOPEFULLY TEMPORARY
   # Basically none of our Tesla mocks in tests set the (supposed to
   # exist for Tesla proper) url parameter for their responses
   # causing almost every fetch in test to fail otherwise
-  if @mix_env == :test do
-    defp check_crossdomain_redirect(nil, _) do
-      {:cross_domain_redirect, false}
-    end
-  end
-
-  defp check_crossdomain_redirect(final_host, original_url) do
-    {:cross_domain_redirect, final_host != URI.parse(original_url).host}
-  end
-
   if @mix_env == :test do
     defp get_final_id(nil, initial_url), do: initial_url
     defp get_final_id("", initial_url), do: initial_url
@@ -371,10 +359,6 @@ def get_object(id) do
     with {:ok, %{body: body, status: code, headers: headers, url: final_url}}
          when code in 200..299 <-
            HTTP.Backoff.get(id, headers),
-         remote_host <-
-           URI.parse(final_url).host,
-         {:cross_domain_redirect, false} <-
-           check_crossdomain_redirect(remote_host, id),
          {:has_content_type, {_, content_type}} <-
            {:has_content_type, List.keyfind(headers, "content-type", 0)},
          {:parse_content_type, {:ok, "application", subtype, type_params}} <-

test/pleroma/object/fetcher_test.exs

@@ -22,6 +22,7 @@ defp spoofed_object_with_ids(
     |> Jason.decode!()
     |> Map.put("id", id)
     |> Map.put("actor", actor_id)
+    |> Map.put("attributedTo", actor_id)
     |> Jason.encode!()
   end
 
@@ -109,7 +110,7 @@ defp spoofed_object_with_ids(
           body: spoofed_object_with_ids("https://patch.cx/objects/spoof_media_redirect1")
         }
 
-      # Spoof: cross-domain redirect with final domain id
+      # Spoof: cross-domain redirect with final domain id, but original id actor
       %{method: :get, url: "https://patch.cx/objects/spoof_media_redirect2"} ->
         %Tesla.Env{
           status: 200,
@@ -118,6 +119,19 @@ defp spoofed_object_with_ids(
           body: spoofed_object_with_ids("https://media.patch.cx/objects/spoof_media_redirect2")
         }
 
+      # No-Spoof: cross-domain redirect with id and actor from final domain
+      %{method: :get, url: "https://patch.cx/objects/spoof_media_redirect3"} ->
+        %Tesla.Env{
+          status: 200,
+          url: "https://media.patch.cx/objects/spoof_media_redirect3",
+          headers: [{"content-type", "application/activity+json"}],
+          body:
+            spoofed_object_with_ids(
+              "https://media.patch.cx/objects/spoof_media_redirect3",
+              "https://media.patch.cx/users/rin"
+            )
+        }
+
       # No-Spoof: same domain redirect
       %{method: :get, url: "https://patch.cx/objects/spoof_redirect"} ->
         %Tesla.Env{
@@ -264,19 +278,29 @@ test "it does not fetch a spoofed object with id different from URL" do
     end
 
     test "it does not fetch an object via cross-domain redirects (initial id)" do
-      assert {:error, {:cross_domain_redirect, true}} =
+      assert {:error, {:containment, _}} =
                Fetcher.fetch_and_contain_remote_object_from_id(
                  "https://patch.cx/objects/spoof_media_redirect1"
                )
     end
 
-    test "it does not fetch an object via cross-domain redirects (final id)" do
-      assert {:error, {:cross_domain_redirect, true}} =
+    test "it does not fetch an object via cross-domain redirect if the actor is from the original domain" do
+      assert {:error, {:containment, :error}} =
                Fetcher.fetch_and_contain_remote_object_from_id(
                  "https://patch.cx/objects/spoof_media_redirect2"
                )
     end
 
+    test "it allows cross-domain redirects when id and author are from final domain" do
+      assert {:ok, %{"id" => id, "attributedTo" => author}} =
+               Fetcher.fetch_and_contain_remote_object_from_id(
+                 "https://patch.cx/objects/spoof_media_redirect3"
+               )
+
+      assert URI.parse(id).host == "media.patch.cx"
+      assert URI.parse(author).host == "media.patch.cx"
+    end
+
     test "it accepts same-domain redirects" do
       assert {:ok, %{"id" => id} = _object} =
                Fetcher.fetch_and_contain_remote_object_from_id(