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Diffstat (limited to 'examples/tcp_listenfd_server.rs')
| -rw-r--r-- | examples/tcp_listenfd_server.rs | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/examples/tcp_listenfd_server.rs b/examples/tcp_listenfd_server.rs new file mode 100644 index 0000000..941d7f0 --- /dev/null +++ b/examples/tcp_listenfd_server.rs @@ -0,0 +1,209 @@ +// You can run this example from the root of the mio repo: +// cargo run --example tcp_listenfd_server --features="os-poll net" +// or with wasi: +// cargo +nightly build --target wasm32-wasi --example tcp_listenfd_server --features="os-poll net" +// wasmtime run --tcplisten 127.0.0.1:9000 --env 'LISTEN_FDS=1' target/wasm32-wasi/debug/examples/tcp_listenfd_server.wasm + +use mio::event::Event; +use mio::net::{TcpListener, TcpStream}; +use mio::{Events, Interest, Poll, Registry, Token}; +use std::collections::HashMap; +use std::io::{self, Read, Write}; +use std::str::from_utf8; + +// Setup some tokens to allow us to identify which event is for which socket. +const SERVER: Token = Token(0); + +// Some data we'll send over the connection. +const DATA: &[u8] = b"Hello world!\n"; + +#[cfg(not(windows))] +fn get_first_listen_fd_listener() -> Option<std::net::TcpListener> { + #[cfg(unix)] + use std::os::unix::io::FromRawFd; + #[cfg(target_os = "wasi")] + use std::os::wasi::io::FromRawFd; + + let stdlistener = unsafe { std::net::TcpListener::from_raw_fd(3) }; + stdlistener.set_nonblocking(true).unwrap(); + Some(stdlistener) +} + +#[cfg(windows)] +fn get_first_listen_fd_listener() -> Option<std::net::TcpListener> { + // Windows does not support `LISTEN_FDS` + None +} + +fn main() -> io::Result<()> { + env_logger::init(); + + std::env::var("LISTEN_FDS").expect("LISTEN_FDS environment variable unset"); + + // Create a poll instance. + let mut poll = Poll::new()?; + // Create storage for events. + let mut events = Events::with_capacity(128); + + // Setup the TCP server socket. + let mut server = { + let stdlistener = get_first_listen_fd_listener().unwrap(); + println!("Using preopened socket FD 3"); + println!("You can connect to the server using `nc`:"); + match stdlistener.local_addr() { + Ok(a) => println!(" $ nc {} {}", a.ip(), a.port()), + Err(_) => println!(" $ nc <IP> <PORT>"), + } + println!("You'll see our welcome message and anything you type will be printed here."); + TcpListener::from_std(stdlistener) + }; + + // Register the server with poll we can receive events for it. + poll.registry() + .register(&mut server, SERVER, Interest::READABLE)?; + + // Map of `Token` -> `TcpStream`. + let mut connections = HashMap::new(); + // Unique token for each incoming connection. + let mut unique_token = Token(SERVER.0 + 1); + + loop { + poll.poll(&mut events, None)?; + + for event in events.iter() { + match event.token() { + SERVER => loop { + // Received an event for the TCP server socket, which + // indicates we can accept an connection. + let (mut connection, address) = match server.accept() { + Ok((connection, address)) => (connection, address), + Err(ref e) if would_block(e) => { + // If we get a `WouldBlock` error we know our + // listener has no more incoming connections queued, + // so we can return to polling and wait for some + // more. + break; + } + Err(e) => { + // If it was any other kind of error, something went + // wrong and we terminate with an error. + return Err(e); + } + }; + + println!("Accepted connection from: {}", address); + + let token = next(&mut unique_token); + poll.registry() + .register(&mut connection, token, Interest::WRITABLE)?; + + connections.insert(token, connection); + }, + token => { + // Maybe received an event for a TCP connection. + let done = if let Some(connection) = connections.get_mut(&token) { + handle_connection_event(poll.registry(), connection, event)? + } else { + // Sporadic events happen, we can safely ignore them. + false + }; + if done { + if let Some(mut connection) = connections.remove(&token) { + poll.registry().deregister(&mut connection)?; + } + } + } + } + } + } +} + +fn next(current: &mut Token) -> Token { + let next = current.0; + current.0 += 1; + Token(next) +} + +/// Returns `true` if the connection is done. +fn handle_connection_event( + registry: &Registry, + connection: &mut TcpStream, + event: &Event, +) -> io::Result<bool> { + if event.is_writable() { + // We can (maybe) write to the connection. + match connection.write(DATA) { + // We want to write the entire `DATA` buffer in a single go. If we + // write less we'll return a short write error (same as + // `io::Write::write_all` does). + Ok(n) if n < DATA.len() => return Err(io::ErrorKind::WriteZero.into()), + Ok(_) => { + // After we've written something we'll reregister the connection + // to only respond to readable events. + registry.reregister(connection, event.token(), Interest::READABLE)? + } + // Would block "errors" are the OS's way of saying that the + // connection is not actually ready to perform this I/O operation. + Err(ref err) if would_block(err) => {} + // Got interrupted (how rude!), we'll try again. + Err(ref err) if interrupted(err) => { + return handle_connection_event(registry, connection, event) + } + // Other errors we'll consider fatal. + Err(err) => return Err(err), + } + } + + if event.is_readable() { + let mut connection_closed = false; + let mut received_data = vec![0; 4096]; + let mut bytes_read = 0; + // We can (maybe) read from the connection. + loop { + match connection.read(&mut received_data[bytes_read..]) { + Ok(0) => { + // Reading 0 bytes means the other side has closed the + // connection or is done writing, then so are we. + connection_closed = true; + break; + } + Ok(n) => { + bytes_read += n; + if bytes_read == received_data.len() { + received_data.resize(received_data.len() + 1024, 0); + } + } + // Would block "errors" are the OS's way of saying that the + // connection is not actually ready to perform this I/O operation. + Err(ref err) if would_block(err) => break, + Err(ref err) if interrupted(err) => continue, + // Other errors we'll consider fatal. + Err(err) => return Err(err), + } + } + + if bytes_read != 0 { + let received_data = &received_data[..bytes_read]; + if let Ok(str_buf) = from_utf8(received_data) { + println!("Received data: {}", str_buf.trim_end()); + } else { + println!("Received (none UTF-8) data: {:?}", received_data); + } + } + + if connection_closed { + println!("Connection closed"); + return Ok(true); + } + } + + Ok(false) +} + +fn would_block(err: &io::Error) -> bool { + err.kind() == io::ErrorKind::WouldBlock +} + +fn interrupted(err: &io::Error) -> bool { + err.kind() == io::ErrorKind::Interrupted +} |