pub async fn recv(&self, recv_buf: &mut [u8]) -> ProxySocketResult<(usize, Address, usize)> {
        self.recv_with_ctrl(recv_buf).await.map(|(n, a, rn, _)| (n, a, rn))
    }
Receive packet from Shadowsocks' UDP server

This function will use `recv_buf` to store intermediate data, so it has to be big enough to store the whole shadowsocks' packet

It is recommended to allocate a buffer to have at least 65536 bytes.
crates/shadowsocks/src/relay/udprelay/proxy_socket.rs