conn_update(struct conn *conn, struct conntrack_bucket *ctb,
            struct dp_packet *pkt, bool reply, long long now)
{
    return l4_protos[conn->key.nw_proto]->conn_update(conn, ctb, pkt,
                                                      reply, now);
}
conn_update(struct conn *conn, struct conntrack_bucket *ctb,
            struct dp_packet *pkt, bool reply, long long now)
{
    return l4_protos[conn->key.nw_proto]->conn_update(conn, ctb, pkt,
                                                      reply, now);
}