pub async fn connect_tcp_local(ns: SocketAddr, connect_opts: &ConnectOpts) -> io::Result<Self> {
        let stream = ShadowTcpStream::connect_with_opts(&ns, connect_opts).await?;
        Ok(Self::TcpLocal { stream })
    }
Connect to local provided TCP DNS server
crates/shadowsocks-service/src/local/dns/upstream.rs