1 files changed, 225 insertions, 0 deletions

diff --git a/embassy-net-examples/src/tuntap.rs b/embassy-net-examples/src/tuntap.rs
new file mode 100644
index 000000000..dd453deb3
--- /dev/null
+++ b/embassy-net-examples/src/tuntap.rs
@@ -0,0 +1,225 @@
+use async_io::Async;
+use libc;
+use log::*;
+use smoltcp::wire::EthernetFrame;
+use std::io;
+use std::io::{Read, Write};
+use std::os::unix::io::{AsRawFd, RawFd};
+
+pub const SIOCGIFMTU: libc::c_ulong = 0x8921;
+pub const SIOCGIFINDEX: libc::c_ulong = 0x8933;
+pub const ETH_P_ALL: libc::c_short = 0x0003;
+pub const TUNSETIFF: libc::c_ulong = 0x400454CA;
+pub const IFF_TUN: libc::c_int = 0x0001;
+pub const IFF_TAP: libc::c_int = 0x0002;
+pub const IFF_NO_PI: libc::c_int = 0x1000;
+
+#[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
+}
+
+fn ifreq_ioctl(
+    lower: libc::c_int,
+    ifreq: &mut ifreq,
+    cmd: libc::c_ulong,
+) -> io::Result<libc::c_int> {
+    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,
+    ifreq: ifreq,
+    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 + EthernetFrame::<&[u8]>::header_len();
+
+            Ok(TunTap { fd, mtu, ifreq })
+        }
+    }
+}
+
+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 embassy_net::{DeviceCapabilities, LinkState, Packet, PacketBox, PacketBoxExt, PacketBuf};
+use std::task::Context;
+
+impl crate::Device for TunTapDevice {
+    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);
+                        let ready = self.device.poll_readable(&mut cx).is_ready();
+                        ready
+                    } 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()
+                }
+            }
+        }
+    }
+
+    fn capabilities(&mut self) -> DeviceCapabilities {
+        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(&mut self) -> [u8; 6] {
+        [0x02, 0x03, 0x04, 0x05, 0x06, 0x07]
+    }
+}