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// Note: `hyper::upgrade` docs link to this upgrade.
extern crate futures;
extern crate hyper;
extern crate tokio;
use std::str;
use futures::sync::oneshot;
use hyper::{Body, Client, Request, Response, Server, StatusCode};
use hyper::header::{UPGRADE, HeaderValue};
use hyper::rt::{self, Future};
use hyper::service::service_fn_ok;
/// Our server HTTP handler to initiate HTTP upgrades.
fn server_upgrade(req: Request<Body>) -> Response<Body> {
let mut res = Response::new(Body::empty());
// Send a 400 to any request that doesn't have
// an `Upgrade` header.
if !req.headers().contains_key(UPGRADE) {
*res.status_mut() = StatusCode::BAD_REQUEST;
return res;
// Setup a future that will eventually receive the upgraded
// connection and talk a new protocol, and spawn the future
// into the runtime.
// Note: This can't possibly be fulfilled until the 101 response
// is returned below, so it's better to spawn this future instead
// waiting for it to complete to then return a response.
let on_upgrade = req
.map_err(|err| eprintln!("upgrade error: {}", err))
.and_then(|upgraded| {
// We have an upgraded connection that we can read and
// write on directly.
// Since we completely control this example, we know exactly
// how many bytes the client will write, so just read exact...
tokio::io::read_exact(upgraded, vec![0; 7])
.and_then(|(upgraded, vec)| {
println!("server[foobar] recv: {:?}", str::from_utf8(&vec));
// And now write back the server 'foobar' protocol's
// response...
tokio::io::write_all(upgraded, b"bar=foo")
.map(|_| println!("server[foobar] sent"))
.map_err(|e| eprintln!("server foobar io error: {}", e))
// Now return a 101 Response saying we agree to the upgrade to some
// made-up 'foobar' protocol.
*res.status_mut() = StatusCode::SWITCHING_PROTOCOLS;
res.headers_mut().insert(UPGRADE, HeaderValue::from_static("foobar"));
fn main() {
// For this example, we just make a server and our own client to talk to
// it, so the exact port isn't important. Instead, let the OS give us an
// unused port.
let addr = ([127, 0, 0, 1], 0).into();
let server = Server::bind(&addr)
.serve(|| service_fn_ok(server_upgrade));
// We need the assigned address for the client to send it messages.
let addr = server.local_addr();
// For this example, a oneshot is used to signal that after 1 request,
// the server should be shutdown.
let (tx, rx) = oneshot::channel();
let server = server
.map_err(|e| eprintln!("server error: {}", e))
.then(|_| Ok(()));
rt::run(rt::lazy(move || {
let req = Request::builder()
.uri(format!("http://{}/", addr))
.header(UPGRADE, "foobar")
.and_then(|res| {
if res.status() != StatusCode::SWITCHING_PROTOCOLS {
panic!("Our server didn't upgrade: {}", res.status());
.map_err(|e| eprintln!("client error: {}", e))
.and_then(|upgraded| {
// We've gotten an upgraded connection that we can read
// and write directly on. Let's start out 'foobar' protocol.
tokio::io::write_all(upgraded, b"foo=bar")
.and_then(|(upgraded, _)| {
println!("client[foobar] sent");
tokio::io::read_to_end(upgraded, Vec::new())
.map(|(_upgraded, vec)| {
println!("client[foobar] recv: {:?}", str::from_utf8(&vec));
// Complete the oneshot so that the server stops
// listening and the process can close down.
let _ = tx.send(());
.map_err(|e| eprintln!("client foobar io error: {}", e))
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