def check_valid_restricted_column(column):
    if column != "0":
        if not calibre_db.session.query(db.Custom_Columns).filter(db.Custom_Columns.id == column) \
              .filter(and_(db.Custom_Columns.datatype == 'text', db.Custom_Columns.mark_for_delete == 0)).all():
            return False
    return True
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.