如何使用rustls库建立TLS连接？

[dependencies]
rustls = "0.20"

use rustls::ClientConfig;
use rustls::Session;

let mut config = ClientConfig::new();
config.root_store.add_server_trust_anchors(&webpki_roots::TLS_SERVER_ROOTS);

let dns_name = webpki::DNSNameRef::try_from_ascii_str("example.com").unwrap();
let mut session = rustls::ClientSession::new(&std::sync::Arc::new(config), dns_name);
let mut socket = TcpStream::connect("example.com:443").unwrap();
let mut tls = rustls::Stream::new(&mut session, &mut socket);

tls.write(b"Hello, server!").unwrap();
let mut buf = [0; 1024];
let size = tls.read(&mut buf).unwrap();