embassy/examples/std/src/tuntap.rs

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use std::io;
use std::io::{Read, Write};
use std::os::unix::io::{AsRawFd, RawFd};
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use async_io::Async;
use log::*;
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pub const SIOCGIFMTU: libc::c_ulong = 0x8921;
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pub const _SIOCGIFINDEX: libc::c_ulong = 0x8933;
pub const _ETH_P_ALL: libc::c_short = 0x0003;
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pub const TUNSETIFF: libc::c_ulong = 0x400454CA;
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pub const _IFF_TUN: libc::c_int = 0x0001;
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pub const IFF_TAP: libc::c_int = 0x0002;
pub const IFF_NO_PI: libc::c_int = 0x1000;
const ETHERNET_HEADER_LEN: usize = 14;
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#[repr(C)]
#[derive(Debug)]
struct ifreq {
ifr_name: [libc::c_char; libc::IF_NAMESIZE],
ifr_data: libc::c_int, /* ifr_ifindex or ifr_mtu */
}
fn ifreq_for(name: &str) -> ifreq {
let mut ifreq = ifreq {
ifr_name: [0; libc::IF_NAMESIZE],
ifr_data: 0,
};
for (i, byte) in name.as_bytes().iter().enumerate() {
ifreq.ifr_name[i] = *byte as libc::c_char
}
ifreq
}
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fn ifreq_ioctl(lower: libc::c_int, ifreq: &mut ifreq, cmd: libc::c_ulong) -> io::Result<libc::c_int> {
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unsafe {
let res = libc::ioctl(lower, cmd as _, ifreq as *mut ifreq);
if res == -1 {
return Err(io::Error::last_os_error());
}
}
Ok(ifreq.ifr_data)
}
#[derive(Debug)]
pub struct TunTap {
fd: libc::c_int,
mtu: usize,
}
impl AsRawFd for TunTap {
fn as_raw_fd(&self) -> RawFd {
self.fd
}
}
impl TunTap {
pub fn new(name: &str) -> io::Result<TunTap> {
unsafe {
let fd = libc::open(
"/dev/net/tun\0".as_ptr() as *const libc::c_char,
libc::O_RDWR | libc::O_NONBLOCK,
);
if fd == -1 {
return Err(io::Error::last_os_error());
}
let mut ifreq = ifreq_for(name);
ifreq.ifr_data = IFF_TAP | IFF_NO_PI;
ifreq_ioctl(fd, &mut ifreq, TUNSETIFF)?;
let socket = libc::socket(libc::AF_INET, libc::SOCK_DGRAM, libc::IPPROTO_IP);
if socket == -1 {
return Err(io::Error::last_os_error());
}
let ip_mtu = ifreq_ioctl(socket, &mut ifreq, SIOCGIFMTU);
libc::close(socket);
let ip_mtu = ip_mtu? as usize;
// SIOCGIFMTU returns the IP MTU (typically 1500 bytes.)
// smoltcp counts the entire Ethernet packet in the MTU, so add the Ethernet header size to it.
let mtu = ip_mtu + ETHERNET_HEADER_LEN;
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Ok(TunTap { fd, mtu })
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}
}
}
impl Drop for TunTap {
fn drop(&mut self) {
unsafe {
libc::close(self.fd);
}
}
}
impl io::Read for TunTap {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let len = unsafe { libc::read(self.fd, buf.as_mut_ptr() as *mut libc::c_void, buf.len()) };
if len == -1 {
Err(io::Error::last_os_error())
} else {
Ok(len as usize)
}
}
}
impl io::Write for TunTap {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
let len = unsafe { libc::write(self.fd, buf.as_ptr() as *mut libc::c_void, buf.len()) };
if len == -1 {
Err(io::Error::last_os_error())
} else {
Ok(len as usize)
}
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
pub struct TunTapDevice {
device: Async<TunTap>,
waker: Option<Waker>,
}
impl TunTapDevice {
pub fn new(name: &str) -> io::Result<TunTapDevice> {
Ok(Self {
device: Async::new(TunTap::new(name)?)?,
waker: None,
})
}
}
use core::task::Waker;
use std::task::Context;
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use embassy_net::{Device, DeviceCapabilities, LinkState, Packet, PacketBox, PacketBoxExt, PacketBuf};
impl Device for TunTapDevice {
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fn is_transmit_ready(&mut self) -> bool {
true
}
fn transmit(&mut self, pkt: PacketBuf) {
// todo handle WouldBlock
match self.device.get_mut().write(&pkt) {
Ok(_) => {}
Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
info!("transmit WouldBlock");
}
Err(e) => panic!("transmit error: {:?}", e),
}
}
fn receive(&mut self) -> Option<PacketBuf> {
let mut pkt = PacketBox::new(Packet::new()).unwrap();
loop {
match self.device.get_mut().read(&mut pkt[..]) {
Ok(n) => {
return Some(pkt.slice(0..n));
}
Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
let ready = if let Some(w) = self.waker.as_ref() {
let mut cx = Context::from_waker(w);
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self.device.poll_readable(&mut cx).is_ready()
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} else {
false
};
if !ready {
return None;
}
}
Err(e) => panic!("read error: {:?}", e),
}
}
}
fn register_waker(&mut self, w: &Waker) {
match self.waker {
// Optimization: If both the old and new Wakers wake the same task, we can simply
// keep the old waker, skipping the clone. (In most executor implementations,
// cloning a waker is somewhat expensive, comparable to cloning an Arc).
Some(ref w2) if (w2.will_wake(w)) => {}
_ => {
// clone the new waker and store it
if let Some(old_waker) = core::mem::replace(&mut self.waker, Some(w.clone())) {
// We had a waker registered for another task. Wake it, so the other task can
// reregister itself if it's still interested.
//
// If two tasks are waiting on the same thing concurrently, this will cause them
// to wake each other in a loop fighting over this WakerRegistration. This wastes
// CPU but things will still work.
//
// If the user wants to have two tasks waiting on the same thing they should use
// a more appropriate primitive that can store multiple wakers.
old_waker.wake()
}
}
}
}
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fn capabilities(&self) -> DeviceCapabilities {
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let mut caps = DeviceCapabilities::default();
caps.max_transmission_unit = self.device.get_ref().mtu;
caps
}
fn link_state(&mut self) -> LinkState {
LinkState::Up
}
fn ethernet_address(&self) -> [u8; 6] {
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[0x02, 0x03, 0x04, 0x05, 0x06, 0x07]
}
}