StatusView: clear MSB on calculated conversation_id

This field seems to be a left-over from the StatusNet era.
If your application uses `pleroma.conversation_id`: this field is
deprecated.

It is currently stubbed instead by doing a CRC32 of the context, and
clearing the MSB to avoid overflow exceptions with signed integers on
the different clients using this field (Java/Kotlin code, mostly; see
Husky and probably other mobile clients.)

This should be removed in a future version of Pleroma. Pleroma-FE
currently depends on this field, as well.

1 files changed, 13 insertions, 2 deletions

diff --git a/lib/pleroma/web/mastodon_api/views/status_view.ex b/lib/pleroma/web/mastodon_api/views/status_view.ex
index 3ffe55c5d..5cb524f56 100644
--- a/lib/pleroma/web/mastodon_api/views/status_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/status_view.ex
@@ -57,8 +57,19 @@ defmodule Pleroma.Web.MastodonAPI.StatusView do
     end)
   end
 
-  defp get_context_id(%{data: %{"context" => context}}) when is_binary(context),
-    do: :erlang.crc32(context)
+  # DEPRECATED This field seems to be a left-over from the StatusNet era.
+  # If your application uses `pleroma.conversation_id`: this field is deprecated.
+  # It is currently stubbed instead by doing a CRC32 of the context, and
+  # clearing the MSB to avoid overflow exceptions with signed integers on the
+  # different clients using this field (Java/Kotlin code, mostly; see Husky.)
+  # This should be removed in a future version of Pleroma. Pleroma-FE currently
+  # depends on this field, as well.
+  defp get_context_id(%{data: %{"context" => context}}) when is_binary(context) do
+    use Bitwise
+
+    :erlang.crc32(context)
+    |> band(bnot(0x8000_0000))
+  end
 
   defp get_context_id(_), do: nil