| //! A simple example of hooking up stdin/stdout to a TCP stream. |
| //! |
| //! This example will connect to a server specified in the argument list and |
| //! then forward all data read on stdin to the server, printing out all data |
| //! received on stdout. |
| //! |
| //! Note that this is not currently optimized for performance, especially around |
| //! buffer management. Rather it's intended to show an example of working with a |
| //! client. |
| |
| extern crate futures; |
| extern crate tokio_core; |
| extern crate tokio_io; |
| extern crate bytes; |
| |
| use std::env; |
| use std::io::{self, Read, Write}; |
| use std::net::SocketAddr; |
| use std::thread; |
| |
| use bytes::{BufMut, BytesMut}; |
| use futures::sync::mpsc; |
| use futures::{Sink, Future, Stream}; |
| use tokio_core::net::TcpStream; |
| use tokio_core::reactor::Core; |
| use tokio_io::AsyncRead; |
| use tokio_io::codec::{Encoder, Decoder}; |
| |
| fn main() { |
| // Parse what address we're going to connect to |
| let addr = env::args().nth(1).unwrap_or_else(|| { |
| panic!("this program requires at least one argument") |
| }); |
| let addr = addr.parse::<SocketAddr>().unwrap(); |
| |
| // Create the event loop and initiate the connection to the remote server |
| let mut core = Core::new().unwrap(); |
| let handle = core.handle(); |
| let tcp = TcpStream::connect(&addr, &handle); |
| |
| // Right now Tokio doesn't support a handle to stdin running on the event |
| // loop, so we farm out that work to a separate thread. This thread will |
| // read data from stdin and then send it to the event loop over a standard |
| // futures channel. |
| let (stdin_tx, stdin_rx) = mpsc::channel(0); |
| thread::spawn(|| read_stdin(stdin_tx)); |
| let stdin_rx = stdin_rx.map_err(|_| panic!()); // errors not possible on rx |
| |
| // After the TCP connection has been established, we set up our client to |
| // start forwarding data. |
| // |
| // First we use the `Io::framed` method with a simple implementation of a |
| // `Codec` (listed below) that just ships bytes around. We then split that |
| // in two to work with the stream and sink separately. |
| // |
| // Half of the work we're going to do is to take all data we receive on |
| // stdin (`stdin_rx`) and send that along the TCP stream (`sink`). The |
| // second half is to take all the data we receive (`stream`) and then write |
| // that to stdout. Currently we just write to stdout in a synchronous |
| // fashion. |
| // |
| // Finally we set the client to terminate once either half of this work |
| // finishes. If we don't have any more data to read or we won't receive any |
| // more work from the remote then we can exit. |
| let mut stdout = io::stdout(); |
| let client = tcp.and_then(|stream| { |
| let (sink, stream) = stream.framed(Bytes).split(); |
| let send_stdin = stdin_rx.forward(sink); |
| let write_stdout = stream.for_each(move |buf| { |
| stdout.write_all(&buf) |
| }); |
| |
| send_stdin.map(|_| ()) |
| .select(write_stdout.map(|_| ())) |
| .then(|_| Ok(())) |
| }); |
| |
| // And now that we've got our client, we execute it in the event loop! |
| core.run(client).unwrap(); |
| } |
| |
| /// A simple `Codec` implementation that just ships bytes around. |
| /// |
| /// This type is used for "framing" a TCP stream of bytes but it's really just a |
| /// convenient method for us to work with streams/sinks for now. This'll just |
| /// take any data read and interpret it as a "frame" and conversely just shove |
| /// data into the output location without looking at it. |
| struct Bytes; |
| |
| impl Decoder for Bytes { |
| type Item = BytesMut; |
| type Error = io::Error; |
| |
| fn decode(&mut self, buf: &mut BytesMut) -> io::Result<Option<BytesMut>> { |
| if buf.len() > 0 { |
| let len = buf.len(); |
| Ok(Some(buf.split_to(len))) |
| } else { |
| Ok(None) |
| } |
| } |
| |
| fn decode_eof(&mut self, buf: &mut BytesMut) -> io::Result<Option<BytesMut>> { |
| self.decode(buf) |
| } |
| } |
| |
| impl Encoder for Bytes { |
| type Item = Vec<u8>; |
| type Error = io::Error; |
| |
| fn encode(&mut self, data: Vec<u8>, buf: &mut BytesMut) -> io::Result<()> { |
| buf.put(&data[..]); |
| Ok(()) |
| } |
| } |
| |
| // Our helper method which will read data from stdin and send it along the |
| // sender provided. |
| fn read_stdin(mut tx: mpsc::Sender<Vec<u8>>) { |
| let mut stdin = io::stdin(); |
| loop { |
| let mut buf = vec![0; 1024]; |
| let n = match stdin.read(&mut buf) { |
| Err(_) | |
| Ok(0) => break, |
| Ok(n) => n, |
| }; |
| buf.truncate(n); |
| tx = tx.send(buf).wait().unwrap(); |
| } |
| } |