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123 lines
4.7 KiB
123 lines
4.7 KiB
//! A chat server that broadcasts a message to all connections.
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//!
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//! This is a simple line-based server which accepts WebSocket connections,
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//! reads lines from those connections, and broadcasts the lines to all other
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//! connected clients.
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//!
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//! You can test this out by running:
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//!
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//! cargo run --example server
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//!
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//! And then in another window run:
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//!
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//! cargo run --example client ws://127.0.0.1:12345/
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//!
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//! You can run the second command in multiple windows and then chat between the
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//! two, seeing the messages from the other client as they're received. For all
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//! connected clients they'll all join the same room and see everyone else's
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//! messages.
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extern crate futures;
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extern crate tokio_core;
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extern crate tokio_tungstenite;
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extern crate tungstenite;
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use std::cell::RefCell;
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use std::collections::HashMap;
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use std::env;
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use std::io::{Error, ErrorKind};
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use std::rc::Rc;
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use futures::stream::Stream;
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use futures::{Future};
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use tokio_core::net::{TcpListener, TcpStream};
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use tokio_core::reactor::Core;
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use tokio_tungstenite::ServerHandshakeExt;
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use tungstenite::handshake::server::ServerHandshake;
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use tungstenite::protocol::Message;
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fn main() {
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let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
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let addr = addr.parse().unwrap();
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// Create the event loop and TCP listener we'll accept connections on.
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let mut core = Core::new().unwrap();
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let handle = core.handle();
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let socket = TcpListener::bind(&addr, &handle).unwrap();
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println!("Listening on: {}", addr);
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// This is a single-threaded server, so we can just use Rc and RefCell to
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// store the map of all connections we know about.
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let connections = Rc::new(RefCell::new(HashMap::new()));
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let srv = socket.incoming().for_each(|(stream, addr)| {
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// We have to clone both of these values, because the `and_then`
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// function billow constructs a new future, `and_then` requires
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// `FnOnce`, so we construct a move closure to move the
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// environment inside the future (AndThen future may overlive our
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// `for_each` future).
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let connections_inner = connections.clone();
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let handle_inner = handle.clone();
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ServerHandshake::<TcpStream>::new_async(stream).and_then(move |ws_stream| {
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println!("New WebSocket connection: {}", addr);
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// Create a channel for our stream, which other sockets will use to
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// send us messages. Then register our address with the stream to send
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// data to us.
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let (tx, rx) = futures::sync::mpsc::unbounded();
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connections_inner.borrow_mut().insert(addr, tx);
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// Let's split the WebSocket stream, so we can work with the
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// reading and writing halves separately.
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let (sink, stream) = ws_stream.split();
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// Whenever we receive a message from the client, we print it and
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// send to other clients, excluding the sender.
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let connections = connections_inner.clone();
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let ws_reader = stream.for_each(move |message: Message| {
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println!("Received a message from {}: {}", addr, message);
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// For each open connection except the sender, send the
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// string via the channel.
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let mut conns = connections.borrow_mut();
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let iter = conns.iter_mut()
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.filter(|&(&k, _)| k != addr)
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.map(|(_, v)| v);
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for tx in iter {
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tx.send(message.clone()).unwrap();
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}
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Ok(())
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});
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// Whenever we receive a string on the Receiver, we write it to
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// `WriteHalf<WebSocketStream>`.
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let ws_writer = rx.fold(sink, |mut sink, msg| {
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use futures::Sink;
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sink.start_send(msg).unwrap();
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Ok(sink)
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});
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// Now that we've got futures representing each half of the socket, we
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// use the `select` combinator to wait for either half to be done to
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// tear down the other. Then we spawn off the result.
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let connection = ws_reader.map(|_| ()).map_err(|_| ())
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.select(ws_writer.map(|_| ()).map_err(|_| ()));
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handle_inner.spawn(connection.then(move |_| {
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connections_inner.borrow_mut().remove(&addr);
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println!("Connection {} closed.", addr);
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Ok(())
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}));
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Ok(())
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}).map_err(|e| {
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println!("Error during the websocket handshake occurred: {}", e);
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Error::new(ErrorKind::Other, e)
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})
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});
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// Execute server.
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core.run(srv).unwrap();
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}
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