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|
//! A proxy that forwards data to another server and forwards that server's
//! responses back to clients.
//!
//! You can showcase this by running this in one terminal:
//!
//! cargo run --example proxy
//!
//! This in another terminal
//!
//! cargo run --example echo
//!
//! And finally this in another terminal
//!
//! cargo run --example connect 127.0.0.1:8081
//!
//! This final terminal will connect to our proxy, which will in turn connect to
//! the echo server, and you'll be able to see data flowing between them.
extern crate futures;
extern crate futures_cpupool;
extern crate tokio;
extern crate tokio_io;
use std::sync::Arc;
use std::env;
use std::net::{Shutdown, SocketAddr};
use std::io::{self, Read, Write};
use futures::stream::Stream;
use futures::{Future, Poll};
use futures::future::Executor;
use futures_cpupool::CpuPool;
use tokio::net::{TcpListener, TcpStream};
use tokio::reactor::Reactor;
use tokio_io::{AsyncRead, AsyncWrite};
use tokio_io::io::{copy, shutdown};
fn main() {
let listen_addr = env::args().nth(1).unwrap_or("127.0.0.1:8081".to_string());
let listen_addr = listen_addr.parse::<SocketAddr>().unwrap();
let server_addr = env::args().nth(2).unwrap_or("127.0.0.1:8080".to_string());
let server_addr = server_addr.parse::<SocketAddr>().unwrap();
// Create the event loop that will drive this server.
let mut l = Reactor::new().unwrap();
let handle = l.handle();
let pool = CpuPool::new(1);
// Create a TCP listener which will listen for incoming connections.
let socket = TcpListener::bind(&listen_addr, &l.handle()).unwrap();
println!("Listening on: {}", listen_addr);
println!("Proxying to: {}", server_addr);
let done = socket.incoming().for_each(move |(client, client_addr)| {
let server = TcpStream::connect(&server_addr, &handle);
let amounts = server.and_then(move |server| {
// Create separate read/write handles for the TCP clients that we're
// proxying data between. Note that typically you'd use
// `AsyncRead::split` for this operation, but we want our writer
// handles to have a custom implementation of `shutdown` which
// actually calls `TcpStream::shutdown` to ensure that EOF is
// transmitted properly across the proxied connection.
//
// As a result, we wrap up our client/server manually in arcs and
// use the impls below on our custom `MyTcpStream` type.
let client_reader = MyTcpStream(Arc::new(client));
let client_writer = client_reader.clone();
let server_reader = MyTcpStream(Arc::new(server));
let server_writer = server_reader.clone();
// Copy the data (in parallel) between the client and the server.
// After the copy is done we indicate to the remote side that we've
// finished by shutting down the connection.
let client_to_server = copy(client_reader, server_writer)
.and_then(|(n, _, server_writer)| {
shutdown(server_writer).map(move |_| n)
});
let server_to_client = copy(server_reader, client_writer)
.and_then(|(n, _, client_writer)| {
shutdown(client_writer).map(move |_| n)
});
client_to_server.join(server_to_client)
});
let msg = amounts.map(move |(from_client, from_server)| {
println!("client at {} wrote {} bytes and received {} bytes",
client_addr, from_client, from_server);
}).map_err(|e| {
// Don't panic. Maybe the client just disconnected too soon.
println!("error: {}", e);
});
pool.execute(msg).unwrap();
Ok(())
});
l.run(done).unwrap();
}
// This is a custom type used to have a custom implementation of the
// `AsyncWrite::shutdown` method which actually calls `TcpStream::shutdown` to
// notify the remote end that we're done writing.
#[derive(Clone)]
struct MyTcpStream(Arc<TcpStream>);
impl Read for MyTcpStream {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
(&*self.0).read(buf)
}
}
impl Write for MyTcpStream {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
(&*self.0).write(buf)
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl AsyncRead for MyTcpStream {}
impl AsyncWrite for MyTcpStream {
fn shutdown(&mut self) -> Poll<(), io::Error> {
try!(self.0.shutdown(Shutdown::Write));
Ok(().into())
}
}
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