net-ppp: Add it.

embassy-net-ppp/src/lib.rs

@@ -0,0 +1,165 @@
+#![no_std]
+#![warn(missing_docs)]
+#![doc = include_str!("../README.md")]
+
+// must be first
+mod fmt;
+
+use core::convert::Infallible;
+use core::mem::MaybeUninit;
+
+use embassy_futures::select::{select3, Either3};
+use embassy_net_driver_channel as ch;
+use embassy_net_driver_channel::driver::LinkState;
+use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+use embassy_sync::signal::Signal;
+use embedded_io_async::{BufRead, Write, WriteAllError};
+use ppproto::pppos::{BufferFullError, PPPoS, PPPoSAction};
+
+const MTU: usize = 1500;
+
+/// Type alias for the embassy-net driver.
+pub type Device<'d> = embassy_net_driver_channel::Device<'d, MTU>;
+
+/// Internal state for the embassy-net integration.
+pub struct State<const N_RX: usize, const N_TX: usize> {
+    ch_state: ch::State<MTU, N_RX, N_TX>,
+}
+
+impl<const N_RX: usize, const N_TX: usize> State<N_RX, N_TX> {
+    /// Create a new `State`.
+    pub const fn new() -> Self {
+        Self {
+            ch_state: ch::State::new(),
+        }
+    }
+}
+
+/// Background runner for the driver.
+///
+/// You must call `.run()` in a background task for the driver to operate.
+pub struct Runner<'d, R: BufRead, W: Write> {
+    ch: ch::Runner<'d, MTU>,
+    r: R,
+    w: W,
+}
+
+/// Error returned by [`Runner::run`].
+#[derive(Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum RunError<RE, WE> {
+    /// Reading from the serial port failed.
+    Read(RE),
+    /// Writing to the serial port failed.
+    Write(WE),
+    /// Writing to the serial port wrote zero bytes, indicating it can't accept more data.
+    WriteZero,
+    /// Writing to the serial got EOF.
+    Eof,
+}
+
+impl<'d, R: BufRead, W: Write> Runner<'d, R, W> {
+    /// You must call this in a background task for the driver to operate.
+    pub async fn run(mut self) -> Result<Infallible, RunError<R::Error, W::Error>> {
+        let config = ppproto::Config {
+            username: b"myuser",
+            password: b"mypass",
+        };
+        let mut ppp = PPPoS::new(config);
+        ppp.open().unwrap();
+
+        let (state_chan, mut rx_chan, mut tx_chan) = self.ch.split();
+        state_chan.set_link_state(LinkState::Down);
+        let _ondrop = OnDrop::new(|| state_chan.set_link_state(LinkState::Down));
+
+        let mut rx_buf = [0; 2048];
+        let mut tx_buf = [0; 2048];
+
+        let poll_signal: Signal<NoopRawMutex, ()> = Signal::new();
+        poll_signal.signal(());
+
+        loop {
+            let mut poll = false;
+            match select3(self.r.fill_buf(), tx_chan.tx_buf(), poll_signal.wait()).await {
+                Either3::First(r) => {
+                    let data = r.map_err(RunError::Read)?;
+                    if data.is_empty() {
+                        return Err(RunError::Eof);
+                    }
+                    let n = ppp.consume(data, &mut rx_buf);
+                    self.r.consume(n);
+                    poll = true;
+                }
+                Either3::Second(pkt) => {
+                    match ppp.send(pkt, &mut tx_buf) {
+                        Ok(n) => match self.w.write_all(&tx_buf[..n]).await {
+                            Ok(()) => {}
+                            Err(WriteAllError::WriteZero) => return Err(RunError::WriteZero),
+                            Err(WriteAllError::Other(e)) => return Err(RunError::Write(e)),
+                        },
+                        Err(BufferFullError) => unreachable!(),
+                    }
+                    tx_chan.tx_done();
+                }
+                Either3::Third(_) => poll = true,
+            }
+
+            if poll {
+                match ppp.poll(&mut tx_buf, &mut rx_buf) {
+                    PPPoSAction::None => {}
+                    PPPoSAction::Received(rg) => {
+                        let pkt = &rx_buf[rg];
+                        let buf = rx_chan.rx_buf().await; // TODO: fix possible deadlock
+                        buf[..pkt.len()].copy_from_slice(pkt);
+                        rx_chan.rx_done(pkt.len());
+
+                        poll_signal.signal(());
+                    }
+                    PPPoSAction::Transmit(n) => {
+                        match self.w.write_all(&tx_buf[..n]).await {
+                            Ok(()) => {}
+                            Err(WriteAllError::WriteZero) => return Err(RunError::WriteZero),
+                            Err(WriteAllError::Other(e)) => return Err(RunError::Write(e)),
+                        }
+                        poll_signal.signal(());
+                    }
+                }
+
+                match ppp.status().phase {
+                    ppproto::Phase::Open => state_chan.set_link_state(LinkState::Up),
+                    _ => state_chan.set_link_state(LinkState::Down),
+                }
+            }
+        }
+    }
+}
+
+/// Create a PPP embassy-net driver instance.
+///
+/// This returns two structs:
+/// - a `Device` that you must pass to the `embassy-net` stack.
+/// - a `Runner`. You must call `.run()` on it in a background task.
+pub fn new<'a, const N_RX: usize, const N_TX: usize, R: BufRead, W: Write>(
+    state: &'a mut State<N_RX, N_TX>,
+    r: R,
+    w: W,
+) -> (Device<'a>, Runner<'a, R, W>) {
+    let (runner, device) = ch::new(&mut state.ch_state, ch::driver::HardwareAddress::Ip);
+    (device, Runner { ch: runner, r, w })
+}
+
+struct OnDrop<F: FnOnce()> {
+    f: MaybeUninit<F>,
+}
+
+impl<F: FnOnce()> OnDrop<F> {
+    fn new(f: F) -> Self {
+        Self { f: MaybeUninit::new(f) }
+    }
+}
+
+impl<F: FnOnce()> Drop for OnDrop<F> {
+    fn drop(&mut self) {
+        unsafe { self.f.as_ptr().read()() }
+    }
+}