'Perform authorization for access that does not require a
confirmed identity.
:returns: A boolean if authorization is granted or denied.  None if
a determination could not be made.'

def _authorize_unconfirmed_identity(self, req, obj, referrers, roles):

    if (req.environ.get('swift_sync_key') and (req.environ['swift_sync_key'] == req.headers.get('x-container-sync-key', None)) and ('x-timestamp' in req.headers)):
        log_msg = 'allowing    proxy    %s    for    container-sync'
        self.logger.debug(log_msg, req.remote_addr)
        return True
    if swift_acl.referrer_allowed(req.referer, referrers):
        if (obj or ('.rlistings' in roles)):
            log_msg = 'authorizing    %s    via    referer    ACL'
            self.logger.debug(log_msg, req.referrer)
            return True
        return False
