'Query router interfaces that relate to list of router_ids.'

def _get_snat_sync_interfaces(self, context, router_ids):

    if (not router_ids):
        return []
    objs = l3_obj.RouterPort.get_objects(context, router_id=router_ids, port_type=const.DEVICE_OWNER_ROUTER_SNAT)
    interfaces = collections.defaultdict(list)
    for rp in objs:
        interfaces[rp.router_id].append(self._core_plugin._make_port_dict(rp.db_obj.port))
    LOG.debug('Return    the    SNAT    ports:    %s', interfaces)
    return interfaces
