message: docs(example): support requests to domain names in example http_proxy
diff: use std::convert::Infallible;
  use std::net::SocketAddr;
  -use futures_util::future::try_join;
  -
  use hyper::service::{make_service_fn, service_fn};
  use hyper::upgrade::Upgraded;
  use hyper::{Body, Client, Method, Request, Response, Server};
  @@ -18,8 +16,8 @@ type HttpClient = Client<hyper::client::HttpConnector>;
  // 2. config http_proxy in command line
  // $ export http_proxy=http://127.0.0.1:8100
  // $ export https_proxy=http://127.0.0.1:8100
  -// 3. send requests (don't use a domain name)
  -// $ curl -i https://8.8.8.8
  +// 3. send requests
  +// $ curl -i https://www.some_domain.com/
  #[tokio::main]
  async fn main() {
  let addr = SocketAddr::from(([127, 0, 0, 1], 8100));
  @@ -88,38 +86,25 @@ async fn proxy(client: HttpClient, req: Request<Body>) -> Result<Response<Body>,
  }
  }
  -fn host_addr(uri: &http::Uri) -> Option<SocketAddr> {
  - uri.authority().and_then(|auth| auth.as_str().parse().ok())
  +fn host_addr(uri: &http::Uri) -> Option<String> {
  + uri.authority().and_then(|auth| Some(auth.to_string()))
  }
  // Create a TCP connection to host:port, build a tunnel between the connection and
  // the upgraded connection
  -async fn tunnel(upgraded: Upgraded, addr: SocketAddr) -> std::io::Result<()> {
  +async fn tunnel(mut upgraded: Upgraded, addr: String) -> std::io::Result<()> {
  // Connect to remote server
  let mut server = TcpStream::connect(addr).await?;
  // Proxying data
  - let amounts = {
  - let (mut server_rd, mut server_wr) = server.split();
  - let (mut client_rd, mut client_wr) = tokio::io::split(upgraded);
  -
  - let client_to_server = tokio::io::copy(&mut client_rd, &mut server_wr);
  - let server_to_client = tokio::io::copy(&mut server_rd, &mut client_wr);
  -
  - try_join(client_to_server, server_to_client).await
  - };
  + let (from_client, from_server) =
  + tokio::io::copy_bidirectional(&mut upgraded, &mut server).await?;
  // Print message when done
  - match amounts {
  - Ok((from_client, from_server)) => {
  println!(
  "client wrote {} bytes and received {} bytes",
  from_client, from_server
  );
  - }
  - Err(e) => {
  - println!("tunnel error: {}", e);
  - }
  - };
  +
  Ok(())
  }
  