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Rust: update network stack to provide blocking impls.

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This commit is contained in:
whitequark 2016-09-20 14:03:31 +00:00
parent dec394bc13
commit 9a24a81f14
5 changed files with 266 additions and 93 deletions
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6
artiq/runtime.rs/Cargo.lock generated
View File

@ -2,7 +2,7 @@
name = "runtime"
version = "0.0.0"
dependencies = [
"fringe 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
"fringe 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
"lwip 0.0.0",
"std_artiq 0.0.0",
]
@ -13,7 +13,7 @@ version = "0.0.0"
[[package]]
name = "fringe"
version = "1.0.5"
version = "1.1.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
"libc 0.2.15 (registry+https://github.com/rust-lang/crates.io-index)",
@ -44,5 +44,5 @@ dependencies = [
]
[metadata]
"checksum fringe 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)" = "c5257685076edffc8f1a85a382135cdf27ba915ac74e47ae55aba19945c17955"
"checksum fringe 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "987689dcfad85eee8d76b477865641ec483e63fb86d52966bfc350c4a647d78a"
"checksum libc 0.2.15 (registry+https://github.com/rust-lang/crates.io-index)" = "23e3757828fa702a20072c37ff47938e9dd331b92fac6e223d26d4b7a55f7ee2"

2
artiq/runtime.rs/Cargo.toml
View File

@ -10,7 +10,7 @@ path = "src/lib.rs"
[dependencies]
std_artiq = { path = "libstd_artiq" }
fringe = { version = "1.0.5", default-features = false, features = ["alloc"] }
fringe = { version = "= 1.1.0", default-features = false, features = ["alloc"] }
lwip = { path = "liblwip" }
[profile.dev]

150
artiq/runtime.rs/liblwip/lib.rs
View File

@ -5,8 +5,10 @@ extern crate alloc;
extern crate collections;
extern crate libc;
extern crate lwip_sys;
extern crate std_artiq as std;
use core::marker::PhantomData;
use core::cell::RefCell;
use alloc::boxed::Box;
use collections::LinkedList;
use libc::c_void;
@ -31,6 +33,47 @@ pub enum Error {
IllegalArgument,
}
impl Error {
fn as_str(&self) -> &str {
match *self {
Error::OutOfMemory => "out of memory error",
Error::Buffer => "buffer error",
Error::Timeout => "timeout",
Error::Routing => "routing error",
Error::InProgress => "operation in progress",
Error::IllegalValue => "illegal value",
Error::WouldBlock => "operation would block",
Error::AddressInUse => "address in use",
Error::AlreadyConnecting => "already connecting",
Error::AlreadyConnected => "already connected",
Error::NotConnected => "not connected",
Error::Interface => "low-level netif error",
Error::ConnectionAborted => "connection aborted",
Error::ConnectionReset => "connection reset",
Error::ConnectionClosed => "connection closed",
Error::IllegalArgument => "illegal argument",
}
}
}
impl std::fmt::Display for Error {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
write!(f, "{}", self.as_str())
}
}
impl std::error::Error for Error {
fn description(&self) -> &str {
self.as_str()
}
}
impl From<Error> for std::io::Error {
fn from(lower: Error) -> std::io::Error {
std::io::Error::new(std::io::ErrorKind::Other, lower)
}
}
pub type Result<T> = core::result::Result<T, Error>;
fn result_from<T, F>(err: lwip_sys::err, f: F) -> Result<T>
@ -165,6 +208,10 @@ impl<'payload> Pbuf<'payload> {
Self::from_slice_with_type(slice, lwip_sys::PBUF_ROM)
}
pub fn len(&self) -> usize {
unsafe { (*self.raw).len as usize }
}
pub fn as_slice(&self) -> &'payload [u8] {
unsafe {
core::slice::from_raw_parts((*self.raw).payload as *const u8,
@ -196,7 +243,7 @@ impl<'a> Drop for Pbuf<'a> {
#[derive(Debug)]
pub struct UdpSocketState {
recv_buffer: LinkedList<(SocketAddr, Pbuf<'static>)>
recv_buffer: LinkedList<(Pbuf<'static>, SocketAddr)>
}
impl UdpSocketState {
@ -208,7 +255,7 @@ impl UdpSocketState {
#[derive(Debug)]
pub struct UdpSocket {
raw: *mut lwip_sys::udp_pcb,
state: Box<UdpSocketState>
state: Box<RefCell<UdpSocketState>>
}
impl UdpSocket {
@ -217,9 +264,9 @@ impl UdpSocket {
pbuf: *mut lwip_sys::pbuf,
addr: *mut lwip_sys::ip_addr, port: u16) {
unsafe {
let state = arg as *mut UdpSocketState;
let state = arg as *mut RefCell<UdpSocketState>;
let socket_addr = SocketAddr { ip: IpAddr::from_raw(addr), port: port };
(*state).recv_buffer.push_back((socket_addr, Pbuf::from_raw(pbuf)));
(*state).borrow_mut().recv_buffer.push_back((Pbuf::from_raw(pbuf), socket_addr));
}
}
@ -227,54 +274,52 @@ impl UdpSocket {
let raw = lwip_sys::udp_new();
if raw.is_null() { return Err(Error::OutOfMemory) }
let mut state = Box::new(UdpSocketState { recv_buffer: LinkedList::new() });
let arg = &mut *state as *mut UdpSocketState as *mut _;
let mut state = Box::new(RefCell::new(UdpSocketState {
recv_buffer: LinkedList::new()
}));
let arg = &mut *state as *mut RefCell<UdpSocketState> as *mut _;
lwip_sys::udp_recv(raw, recv, arg);
Ok(UdpSocket { raw: raw, state: state })
}
}
pub fn state(&self) -> *const UdpSocketState {
pub fn state(&self) -> *const RefCell<UdpSocketState> {
&*self.state
}
pub fn bind(&mut self, addr: SocketAddr) -> Result<()> {
pub fn bind(&self, addr: SocketAddr) -> Result<()> {
result_from(unsafe {
lwip_sys::udp_bind(self.raw, &mut addr.ip.into_raw(), addr.port)
}, || ())
}
pub fn connect(&mut self, addr: SocketAddr) -> Result<()> {
pub fn connect(&self, addr: SocketAddr) -> Result<()> {
result_from(unsafe {
lwip_sys::udp_connect(self.raw, &mut addr.ip.into_raw(), addr.port)
}, || ())
}
pub fn disconnect(&mut self) -> Result<()> {
pub fn disconnect(&self) -> Result<()> {
result_from(unsafe {
lwip_sys::udp_disconnect(self.raw)
}, || ())
}
pub fn send<'a>(&'a mut self, pbuf: Pbuf<'a>) -> Result<()> {
pub fn send<'a>(&'a self, pbuf: Pbuf<'a>) -> Result<()> {
result_from(unsafe {
lwip_sys::udp_send(self.raw, pbuf.as_raw())
}, || ())
}
pub fn send_to<'a>(&'a mut self, addr: SocketAddr, pbuf: Pbuf<'a>) -> Result<()> {
pub fn send_to<'a>(&'a self, pbuf: Pbuf<'a>, addr: SocketAddr) -> Result<()> {
result_from(unsafe {
lwip_sys::udp_sendto(self.raw, pbuf.as_raw(),
&mut addr.ip.into_raw(), addr.port)
}, || ())
}
pub fn try_recv(&mut self) -> Option<(SocketAddr, Pbuf<'static>)> {
self.state.recv_buffer.pop_front()
}
pub fn close(self) {
// just drop
pub fn try_recv(&self) -> Option<(Pbuf<'static>, SocketAddr)> {
self.state.borrow_mut().recv_buffer.pop_front()
}
}
@ -298,7 +343,7 @@ impl TcpListenerState {
#[derive(Debug)]
pub struct TcpListener {
raw: *mut lwip_sys::tcp_pcb,
state: Box<TcpListenerState>
state: Box<RefCell<TcpListenerState>>
}
impl TcpListener {
@ -307,8 +352,8 @@ impl TcpListener {
err: lwip_sys::err) -> lwip_sys::err {
if err != lwip_sys::ERR_OK { return err }
unsafe {
let state = arg as *mut TcpListenerState;
(*state).backlog.push_back(TcpStream::from_raw(newpcb));
let state = arg as *mut RefCell<TcpListenerState>;
(*state).borrow_mut().backlog.push_back(TcpStream::from_raw(newpcb));
}
lwip_sys::ERR_OK
}
@ -325,26 +370,22 @@ impl TcpListener {
return Err(Error::OutOfMemory)
}
let mut state = Box::new(TcpListenerState {
let mut state = Box::new(RefCell::new(TcpListenerState {
backlog: LinkedList::new()
});
let arg = &mut *state as *mut TcpListenerState as *mut _;
}));
let arg = &mut *state as *mut RefCell<TcpListenerState> as *mut _;
lwip_sys::tcp_arg(raw, arg);
lwip_sys::tcp_accept(raw2, accept);
Ok(TcpListener { raw: raw2, state: state })
}
}
pub fn state(&self) -> *const TcpListenerState {
pub fn state(&self) -> *const RefCell<TcpListenerState> {
&*self.state
}
pub fn try_accept(&mut self) -> Option<TcpStream> {
self.state.backlog.pop_front()
}
pub fn close(self) {
// just drop
pub fn try_accept(&self) -> Option<TcpStream> {
self.state.borrow_mut().backlog.pop_front()
}
}
@ -383,7 +424,7 @@ impl TcpStreamState {
#[derive(Debug)]
pub struct TcpStream {
raw: *mut lwip_sys::tcp_pcb,
state: Box<TcpStreamState>
state: Box<RefCell<TcpStreamState>>
}
impl TcpStream {
@ -392,11 +433,11 @@ impl TcpStream {
pbuf: *mut lwip_sys::pbuf, err: lwip_sys::err) -> lwip_sys::err {
if err != lwip_sys::ERR_OK { return err }
unsafe {
let state = arg as *mut TcpStreamState;
let state = arg as *mut RefCell<TcpStreamState>;
if pbuf.is_null() {
(*state).recv_buffer.push_back(Err(Error::ConnectionClosed))
(*state).borrow_mut().recv_buffer.push_back(Err(Error::ConnectionClosed))
} else {
(*state).recv_buffer.push_back(Ok(Pbuf::from_raw(pbuf)))
(*state).borrow_mut().recv_buffer.push_back(Ok(Pbuf::from_raw(pbuf)))
}
}
lwip_sys::ERR_OK
@ -405,25 +446,25 @@ impl TcpStream {
extern fn sent(arg: *mut c_void, raw: *mut lwip_sys::tcp_pcb,
_len: u16) -> lwip_sys::err {
unsafe {
let state = arg as *mut TcpStreamState;
(*state).send_avail = lwip_sys::tcp_sndbuf_(raw) as usize;
let state = arg as *mut RefCell<TcpStreamState>;
(*state).borrow_mut().send_avail = lwip_sys::tcp_sndbuf_(raw) as usize;
}
lwip_sys::ERR_OK
}
extern fn err(arg: *mut c_void, err: lwip_sys::err) {
unsafe {
let state = arg as *mut TcpStreamState;
(*state).recv_buffer.push_back(result_from(err, || unreachable!()))
let state = arg as *mut RefCell<TcpStreamState>;
(*state).borrow_mut().recv_buffer.push_back(result_from(err, || unreachable!()))
}
}
unsafe {
let mut state = Box::new(TcpStreamState {
let mut state = Box::new(RefCell::new(TcpStreamState {
recv_buffer: LinkedList::new(),
send_avail: lwip_sys::tcp_sndbuf_(raw) as usize
});
let arg = &mut *state as *mut TcpStreamState as *mut _;
}));
let arg = &mut *state as *mut RefCell<TcpStreamState> as *mut _;
lwip_sys::tcp_arg(raw, arg);
lwip_sys::tcp_recv(raw, recv);
lwip_sys::tcp_sent(raw, sent);
@ -432,34 +473,43 @@ impl TcpStream {
}
}
pub fn state(&self) -> *const TcpStreamState {
pub fn state(&self) -> *const RefCell<TcpStreamState> {
&*self.state
}
pub fn write(&mut self, data: &[u8]) -> Result<usize> {
pub fn write(&self, data: &[u8]) -> Result<usize> {
let sndbuf = unsafe { lwip_sys::tcp_sndbuf_(self.raw) } as usize;
let len = if data.len() < sndbuf { data.len() } else { sndbuf };
let result = result_from(unsafe {
lwip_sys::tcp_write(self.raw, data as *const [u8] as *const _, len as u16,
lwip_sys::TCP_WRITE_FLAG_COPY)
lwip_sys::TCP_WRITE_FLAG_COPY |
lwip_sys::TCP_WRITE_FLAG_MORE)
}, || len);
self.state.send_avail = unsafe { lwip_sys::tcp_sndbuf_(self.raw) } as usize;
self.state.borrow_mut().send_avail = unsafe { lwip_sys::tcp_sndbuf_(self.raw) } as usize;
result
}
pub fn try_read(&mut self) -> Result<Option<Pbuf<'static>>> {
match self.state.recv_buffer.front() {
pub fn flush(&self) -> Result<()> {
const EMPTY_DATA: [u8; 0] = [];
result_from(unsafe {
lwip_sys::tcp_write(self.raw, &EMPTY_DATA as *const [u8] as *const _, 0, 0)
}, || ())
}
pub fn try_read(&self) -> Result<Option<Pbuf<'static>>> {
let mut state = self.state.borrow_mut();
match state.recv_buffer.front() {
None => return Ok(None),
Some(&Err(err)) => return Err(err),
Some(_) => ()
}
match self.state.recv_buffer.pop_front() {
match state.recv_buffer.pop_front() {
Some(Ok(pbuf)) => return Ok(Some(pbuf)),
_ => unreachable!()
}
}
pub fn shutdown(&mut self, how: Shutdown) -> Result<()> {
pub fn shutdown(&self, how: Shutdown) -> Result<()> {
let (shut_rx, shut_tx) = match how {
Shutdown::Read => (1, 0),
Shutdown::Write => (0, 1),

181
artiq/runtime.rs/src/io.rs
View File

@ -1,8 +1,10 @@
extern crate fringe;
extern crate lwip;
use std::cell::RefCell;
use std::vec::Vec;
use std::time::{Instant, Duration};
use std::io::{Read, Write, Result, Error, ErrorKind};
use self::fringe::OwnedStack;
use self::fringe::generator::{Generator, Yielder};
@ -37,7 +39,7 @@ impl Scheduler {
Scheduler { threads: Vec::new(), index: 0 }
}
pub unsafe fn spawn<F: FnOnce(Waiter) + Send>(&mut self, stack_size: usize, f: F) {
pub unsafe fn spawn<F: FnOnce(Waiter) + Send + 'static>(&mut self, stack_size: usize, f: F) {
let stack = OwnedStack::new(stack_size);
let thread = Thread {
generator: Generator::unsafe_new(stack, move |yielder, _| {
@ -104,43 +106,34 @@ impl Scheduler {
#[derive(Debug)]
enum WaitEvent {
UdpReadable(*const lwip::UdpSocketState),
TcpAcceptable(*const lwip::TcpListenerState),
TcpWriteable(*const lwip::TcpStreamState),
TcpReadable(*const lwip::TcpStreamState),
UdpReadable(*const RefCell<lwip::UdpSocketState>),
TcpAcceptable(*const RefCell<lwip::TcpListenerState>),
TcpWriteable(*const RefCell<lwip::TcpStreamState>),
TcpReadable(*const RefCell<lwip::TcpStreamState>),
}
impl WaitEvent {
fn completed(&self) -> bool {
match *self {
WaitEvent::UdpReadable(state) =>
unsafe { (*state).readable() },
unsafe { (*state).borrow().readable() },
WaitEvent::TcpAcceptable(state) =>
unsafe { (*state).acceptable() },
unsafe { (*state).borrow().acceptable() },
WaitEvent::TcpWriteable(state) =>
unsafe { (*state).writeable() },
unsafe { (*state).borrow().writeable() },
WaitEvent::TcpReadable(state) =>
unsafe { (*state).readable() },
unsafe { (*state).borrow().readable() },
}
}
}
unsafe impl Send for WaitEvent {}
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub enum Error {
Lwip(lwip::Error),
TimedOut,
Interrupted
}
pub type Result<T> = ::std::result::Result<T, Error>;
#[derive(Debug)]
pub struct Waiter<'a>(&'a mut Yielder<WaitResult, WaitRequest, OwnedStack>);
#[derive(Debug, Clone, Copy)]
pub struct Waiter<'a>(&'a Yielder<WaitResult, WaitRequest, OwnedStack>);
impl<'a> Waiter<'a> {
pub fn sleep(&mut self, duration: Duration) -> Result<()> {
pub fn sleep(&self, duration: Duration) -> Result<()> {
let request = WaitRequest {
timeout: Some(Instant::now() + duration),
event: None
@ -148,44 +141,174 @@ impl<'a> Waiter<'a> {
match self.0.suspend(request) {
WaitResult::TimedOut => Ok(()),
WaitResult::Interrupted => Err(Error::Interrupted),
WaitResult::Interrupted => Err(Error::new(ErrorKind::Interrupted, "")),
_ => unreachable!()
}
}
fn suspend(&mut self, request: WaitRequest) -> Result<()> {
fn suspend(&self, request: WaitRequest) -> Result<()> {
match self.0.suspend(request) {
WaitResult::Completed => Ok(()),
WaitResult::TimedOut => Err(Error::TimedOut),
WaitResult::Interrupted => Err(Error::Interrupted)
WaitResult::TimedOut => Err(Error::new(ErrorKind::TimedOut, "")),
WaitResult::Interrupted => Err(Error::new(ErrorKind::Interrupted, ""))
}
}
pub fn udp_readable(&mut self, socket: &lwip::UdpSocket) -> Result<()> {
pub fn udp_readable(&self, socket: &lwip::UdpSocket) -> Result<()> {
self.suspend(WaitRequest {
timeout: None,
event: Some(WaitEvent::UdpReadable(socket.state()))
})
}
pub fn tcp_acceptable(&mut self, socket: &lwip::TcpListener) -> Result<()> {
pub fn tcp_acceptable(&self, socket: &lwip::TcpListener) -> Result<()> {
self.suspend(WaitRequest {
timeout: None,
event: Some(WaitEvent::TcpAcceptable(socket.state()))
})
}
pub fn tcp_writeable(&mut self, socket: &lwip::TcpStream) -> Result<()> {
pub fn tcp_writeable(&self, socket: &lwip::TcpStream) -> Result<()> {
self.suspend(WaitRequest {
timeout: None,
event: Some(WaitEvent::TcpWriteable(socket.state()))
})
}
pub fn tcp_readable(&mut self, socket: &lwip::TcpStream) -> Result<()> {
pub fn tcp_readable(&self, socket: &lwip::TcpStream) -> Result<()> {
self.suspend(WaitRequest {
timeout: None,
event: Some(WaitEvent::TcpReadable(socket.state()))
})
}
}
// Wrappers around lwip
pub use self::lwip::{IpAddr, IP4_ANY, IP6_ANY, IP_ANY, SocketAddr};
#[derive(Debug)]
pub struct UdpSocket<'a> {
waiter: Waiter<'a>,
lower: lwip::UdpSocket
}
impl<'a> UdpSocket<'a> {
pub fn new(waiter: Waiter<'a>) -> Result<UdpSocket> {
Ok(UdpSocket {
waiter: waiter,
lower: try!(lwip::UdpSocket::new())
})
}
pub fn bind(&self, addr: SocketAddr) -> Result<()> {
Ok(try!(self.lower.bind(addr)))
}
pub fn connect(&self, addr: SocketAddr) -> Result<()> {
Ok(try!(self.lower.connect(addr)))
}
pub fn disconnect(&self) -> Result<()> {
Ok(try!(self.lower.disconnect()))
}
pub fn send_to(&self, buf: &[u8], addr: SocketAddr) -> Result<usize> {
try!(self.lower.send_to(lwip::Pbuf::from_slice(buf), addr));
Ok(buf.len())
}
pub fn recv_from(&self, buf: &mut [u8]) -> Result<(usize, SocketAddr)> {
try!(self.waiter.udp_readable(&self.lower));
let (pbuf, addr) = self.lower.try_recv().unwrap();
let len = ::std::cmp::min(buf.len(), pbuf.len());
(&mut buf[..len]).copy_from_slice(&pbuf.as_slice()[..len]);
Ok((len, addr))
}
pub fn send(&self, buf: &[u8]) -> Result<usize> {
try!(self.lower.send(lwip::Pbuf::from_slice(buf)));
Ok(buf.len())
}
pub fn recv(&self, buf: &mut [u8]) -> Result<usize> {
try!(self.waiter.udp_readable(&self.lower));
let (pbuf, _addr) = self.lower.try_recv().unwrap();
// lwip checks that addr matches the bind/connect call
let len = ::std::cmp::min(buf.len(), pbuf.len());
(&mut buf[..len]).copy_from_slice(&pbuf.as_slice()[..len]);
Ok(len)
}
}
#[derive(Debug)]
pub struct TcpListener<'a> {
waiter: Waiter<'a>,
lower: lwip::TcpListener
}
impl<'a> TcpListener<'a> {
pub fn bind(waiter: Waiter<'a>, addr: SocketAddr) -> Result<TcpListener> {
Ok(TcpListener {
waiter: waiter,
lower: try!(lwip::TcpListener::bind(addr))
})
}
pub fn accept(&self) -> Result<(TcpStream, SocketAddr)> {
try!(self.waiter.tcp_acceptable(&self.lower));
loop {}
let stream_lower = self.lower.try_accept().unwrap();
let addr = SocketAddr::new(IP_ANY, 0); // FIXME: coax lwip into giving real addr here
Ok((TcpStream {
waiter: self.waiter,
lower: stream_lower,
buffer: None
}, addr))
}
}
pub use self::lwip::Shutdown;
#[derive(Debug)]
pub struct TcpStream<'a> {
waiter: Waiter<'a>,
lower: lwip::TcpStream,
buffer: Option<(lwip::Pbuf<'static>, usize)>
}
impl<'a> TcpStream<'a> {
pub fn shutdown(&self, how: Shutdown) -> Result<()> {
Ok(try!(self.lower.shutdown(how)))
}
}
impl<'a> Read for TcpStream<'a> {
fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
if self.buffer.is_none() {
try!(self.waiter.tcp_readable(&self.lower));
let pbuf = try!(self.lower.try_read()).unwrap();
self.buffer = Some((pbuf, 0))
}
let (pbuf, pos) = self.buffer.take().unwrap();
let slice = &pbuf.as_slice()[pos..];
let len = ::std::cmp::min(buf.len(), slice.len());
buf.copy_from_slice(&slice[..len]);
if len < slice.len() {
self.buffer = Some((pbuf, pos + len))
}
Ok(len)
}
}
impl<'a> Write for TcpStream<'a> {
fn write(&mut self, buf: &[u8]) -> Result<usize> {
try!(self.waiter.tcp_writeable(&self.lower));
Ok(try!(self.lower.write(buf)))
}
fn flush(&mut self) -> Result<()> {
Ok(try!(self.lower.flush()))
}
}

20
artiq/runtime.rs/src/lib.rs
View File

@ -2,8 +2,6 @@
#[macro_use]
extern crate std_artiq as std;
extern crate fringe;
extern crate lwip;
use std::prelude::v1::*;
@ -14,21 +12,23 @@ extern {
fn lwip_service();
}
fn timer(mut waiter: io::Waiter) {
fn timer(waiter: io::Waiter) {
loop {
println!("tick");
waiter.sleep(std::time::Duration::from_millis(1000)).unwrap();
}
}
fn echo(mut waiter: io::Waiter) {
let mut socket = lwip::UdpSocket::new().unwrap();
socket.bind(lwip::SocketAddr::new(lwip::IP_ANY, 1234)).unwrap();
fn echo(waiter: io::Waiter) {
let addr = io::SocketAddr::new(io::IP_ANY, 1234);
let listener = io::TcpListener::bind(waiter, addr).unwrap();
loop {
waiter.udp_readable(&socket).unwrap();
let (addr, pbuf) = socket.try_recv().unwrap();
println!("{:?}", core::str::from_utf8(pbuf.as_slice()));
socket.send_to(addr, pbuf).unwrap();
let (mut stream, _addr) = listener.accept().unwrap();
loop {
let mut buf = [0];
stream.read(&mut buf).unwrap();
stream.write(&buf).unwrap();
}
}
}