net: move tuntap from std example to separate crate. (#1737)

1 files changed, 225 insertions, 0 deletions

diff --git a/embassy-net-tuntap/src/lib.rs b/embassy-net-tuntap/src/lib.rs
new file mode 100644
index 000000000..75c54c487
--- /dev/null
+++ b/embassy-net-tuntap/src/lib.rs
@@ -0,0 +1,225 @@
+use std::io;
+use std::io::{Read, Write};
+use std::os::unix::io::{AsRawFd, RawFd};
+use std::task::Context;
+
+use async_io::Async;
+use embassy_net_driver::{self, Capabilities, Driver, HardwareAddress, LinkState};
+use log::*;
+
+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;
+
+const ETHERNET_HEADER_LEN: usize = 14;
+
+#[repr(C)]
+#[derive(Debug)]
+#[allow(non_camel_case_types)]
+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,
+    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;
+
+            Ok(TunTap { fd, mtu })
+        }
+    }
+}
+
+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>,
+}
+
+impl TunTapDevice {
+    pub fn new(name: &str) -> io::Result<TunTapDevice> {
+        Ok(Self {
+            device: Async::new(TunTap::new(name)?)?,
+        })
+    }
+}
+
+impl Driver for TunTapDevice {
+    type RxToken<'a> = RxToken where Self: 'a;
+    type TxToken<'a> = TxToken<'a> where Self: 'a;
+
+    fn receive(&mut self, cx: &mut Context) -> Option<(Self::RxToken<'_>, Self::TxToken<'_>)> {
+        let mut buf = vec![0; self.device.get_ref().mtu];
+        loop {
+            match self.device.get_mut().read(&mut buf) {
+                Ok(n) => {
+                    buf.truncate(n);
+                    return Some((
+                        RxToken { buffer: buf },
+                        TxToken {
+                            device: &mut self.device,
+                        },
+                    ));
+                }
+                Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                    if !self.device.poll_readable(cx).is_ready() {
+                        return None;
+                    }
+                }
+                Err(e) => panic!("read error: {:?}", e),
+            }
+        }
+    }
+
+    fn transmit(&mut self, _cx: &mut Context) -> Option<Self::TxToken<'_>> {
+        Some(TxToken {
+            device: &mut self.device,
+        })
+    }
+
+    fn capabilities(&self) -> Capabilities {
+        let mut caps = Capabilities::default();
+        caps.max_transmission_unit = self.device.get_ref().mtu;
+        caps
+    }
+
+    fn link_state(&mut self, _cx: &mut Context) -> LinkState {
+        LinkState::Up
+    }
+
+    fn hardware_address(&self) -> HardwareAddress {
+        HardwareAddress::Ethernet([0x02, 0x03, 0x04, 0x05, 0x06, 0x07])
+    }
+}
+
+#[doc(hidden)]
+pub struct RxToken {
+    buffer: Vec<u8>,
+}
+
+impl embassy_net_driver::RxToken for RxToken {
+    fn consume<R, F>(mut self, f: F) -> R
+    where
+        F: FnOnce(&mut [u8]) -> R,
+    {
+        f(&mut self.buffer)
+    }
+}
+
+#[doc(hidden)]
+pub struct TxToken<'a> {
+    device: &'a mut Async<TunTap>,
+}
+
+impl<'a> embassy_net_driver::TxToken for TxToken<'a> {
+    fn consume<R, F>(self, len: usize, f: F) -> R
+    where
+        F: FnOnce(&mut [u8]) -> R,
+    {
+        let mut buffer = vec![0; len];
+        let result = f(&mut buffer);
+
+        // todo handle WouldBlock with async
+        match self.device.get_mut().write(&buffer) {
+            Ok(_) => {}
+            Err(e) if e.kind() == io::ErrorKind::WouldBlock => info!("transmit WouldBlock"),
+            Err(e) => panic!("transmit error: {:?}", e),
+        }
+
+        result
+    }
+}