fix: Conditionally allow for ignoring unknown media for profile avatars when propagating membership events

Borrow the experimental setting that disables legacy media uploads

Author: jason-famedly

synapse/handlers/room_member.py

@@ -110,6 +110,8 @@ def __init__(self, hs: "HomeServer"):
         self.event_auth_handler = hs.get_event_auth_handler()
         self._worker_lock_handler = hs.get_worker_locks_handler()
         self.enable_restricted_media = hs.config.experimental.msc3911_enabled
+        # This is technically wrong, but works for proof of concept
+        self.allow_legacy_media = not hs.config.experimental.msc3911_unrestricted_media_upload_disabled
 
         self._membership_types_to_include_profile_data_in = {
             Membership.JOIN,
@@ -869,15 +871,24 @@ async def update_membership_locked(
                     # Something about the MediaRepository does not like being part of
                     # the initialization code of the RoomMemberHandler, so just import
                     # it on the spot instead.
-                    media_repo = self.hs.get_media_repository()
+                    media_repo = self.hs.get_media_repository() #
 
-                    new_mxc_uri = await media_repo.copy_media(
-                        MXCUri.from_str(avatar_url), requester.user, 20_000
-                    )
-                    media_object = await media_repo.get_media_info(new_mxc_uri)
-                    assert isinstance(media_object, LocalMedia)
-                    media_info_for_attachment = {media_object}
-                    content[EventContentFields.MEMBERSHIP_AVATAR_URL] = str(new_mxc_uri)
+                    try:
+                        new_mxc_uri = await media_repo.copy_media(
+                            MXCUri.from_str(avatar_url), requester.user, 20_000
+                        )
+                    except SynapseError:
+                        # The copy command can fail if the media doesn't already exist.
+                        # In this case, if legacy media is allowed, ignore it. Otherwise, deny it and re-raise
+                        if self.allow_legacy_media:
+                            pass
+                        else:
+                            raise
+                    else:
+                        media_object = await media_repo.get_media_info(new_mxc_uri)
+                        assert isinstance(media_object, LocalMedia)
+                        media_info_for_attachment = {media_object}
+                        content[EventContentFields.MEMBERSHIP_AVATAR_URL] = str(new_mxc_uri)
 
         # if this is a join with a 3pid signature, we may need to turn a 3pid
         # invite into a normal invite before we can handle the join.