Implement embedded-nal-async traits for embassy-net

3 files changed, 171 insertions, 1 deletions

diff --git a/embassy-net/Cargo.toml b/embassy-net/Cargo.toml
index 64cb5bd8f..fface207b 100644
--- a/embassy-net/Cargo.toml
+++ b/embassy-net/Cargo.toml
@@ -31,6 +31,7 @@ pool-16 = []
 pool-32 = []
 pool-64 = []
 pool-128 = []
+unstable-traits = []
 
 [dependencies]
 
@@ -48,6 +49,8 @@ generic-array       = { version = "0.14.4", default-features = false }
 stable_deref_trait  = { version = "1.2.0", default-features = false }
 futures             = { version = "0.3.17", default-features = false, features = [ "async-await" ] }
 atomic-pool = "0.2.1"
+atomic-polyfill = "0.1.5"
+embedded-nal-async = "0.2.0"
 
 [dependencies.smoltcp]
 version = "0.8.0"
diff --git a/embassy-net/src/tcp.rs b/embassy-net/src/tcp.rs
index c18391ace..96a6dfe28 100644
--- a/embassy-net/src/tcp.rs
+++ b/embassy-net/src/tcp.rs
@@ -328,3 +328,170 @@ impl<'d> embedded_io::asynch::Write for TcpWriter<'d> {
         self.io.flush()
     }
 }
+
+#[cfg(feature = "unstable-traits")]
+pub mod client {
+    use core::mem::MaybeUninit;
+    use core::ptr::NonNull;
+
+    use atomic_polyfill::{AtomicBool, Ordering};
+    use embedded_nal_async::IpAddr;
+
+    use super::*;
+
+    pub struct TcpClient<'d, D: Device, const N: usize, const TX_SZ: usize = 1024, const RX_SZ: usize = 1024> {
+        stack: &'d Stack<D>,
+        tx: &'d BufferPool<TX_SZ, N>,
+        rx: &'d BufferPool<RX_SZ, N>,
+    }
+
+    impl<'d, D: Device, const N: usize, const TX_SZ: usize, const RX_SZ: usize> TcpClient<'d, D, N, TX_SZ, RX_SZ> {
+        pub fn new(stack: &'d Stack<D>, tx: &'d BufferPool<TX_SZ, N>, rx: &'d BufferPool<RX_SZ, N>) -> Self {
+            Self { stack, tx, rx }
+        }
+    }
+
+    impl<'d, D: Device, const N: usize, const TX_SZ: usize, const RX_SZ: usize> embedded_nal_async::TcpConnect
+        for TcpClient<'d, D, N, TX_SZ, RX_SZ>
+    {
+        type Error = Error;
+        type Connection<'m> = TcpConnection<'m, N, TX_SZ, RX_SZ> where Self: 'm;
+        type ConnectFuture<'m> = impl Future<Output = Result<Self::Connection<'m>, Self::Error>> + 'm
+    where
+        Self: 'm;
+
+        fn connect<'m>(&'m self, remote: embedded_nal_async::SocketAddr) -> Self::ConnectFuture<'m> {
+            async move {
+                let addr: crate::IpAddress = match remote.ip() {
+                    IpAddr::V4(addr) => crate::IpAddress::Ipv4(crate::Ipv4Address::from_bytes(&addr.octets())),
+                    #[cfg(feature = "proto-ipv6")]
+                    IpAddr::V6(addr) => crate::IpAddress::Ipv6(crate::Ipv6Address::from_bytes(&addr.octets())),
+                    #[cfg(not(feature = "proto-ipv6"))]
+                    IpAddr::V6(_) => panic!("ipv6 support not enabled"),
+                };
+                let remote_endpoint = (addr, remote.port());
+                let mut socket = TcpConnection::new(&self.stack, self.tx, self.rx)?;
+                socket
+                    .socket
+                    .connect(remote_endpoint)
+                    .await
+                    .map_err(|_| Error::ConnectionReset)?;
+                Ok(socket)
+            }
+        }
+    }
+
+    pub struct TcpConnection<'d, const N: usize, const TX_SZ: usize, const RX_SZ: usize> {
+        socket: TcpSocket<'d>,
+        tx: &'d BufferPool<TX_SZ, N>,
+        rx: &'d BufferPool<RX_SZ, N>,
+        txb: NonNull<[u8; TX_SZ]>,
+        rxb: NonNull<[u8; RX_SZ]>,
+    }
+
+    impl<'d, const N: usize, const TX_SZ: usize, const RX_SZ: usize> TcpConnection<'d, N, TX_SZ, RX_SZ> {
+        fn new<D: Device>(
+            stack: &'d Stack<D>,
+            tx: &'d BufferPool<TX_SZ, N>,
+            rx: &'d BufferPool<RX_SZ, N>,
+        ) -> Result<Self, Error> {
+            let mut txb = tx.alloc().ok_or(Error::ConnectionReset)?;
+            let mut rxb = rx.alloc().ok_or(Error::ConnectionReset)?;
+            Ok(Self {
+                socket: unsafe { TcpSocket::new(stack, rxb.as_mut(), txb.as_mut()) },
+                tx,
+                rx,
+                txb,
+                rxb,
+            })
+        }
+    }
+
+    impl<'d, const N: usize, const TX_SZ: usize, const RX_SZ: usize> Drop for TcpConnection<'d, N, TX_SZ, RX_SZ> {
+        fn drop(&mut self) {
+            unsafe {
+                self.socket.close();
+                self.rx.free(self.rxb);
+                self.tx.free(self.txb);
+            }
+        }
+    }
+
+    impl<'d, const N: usize, const TX_SZ: usize, const RX_SZ: usize> embedded_io::Io
+        for TcpConnection<'d, N, TX_SZ, RX_SZ>
+    {
+        type Error = Error;
+    }
+
+    impl<'d, const N: usize, const TX_SZ: usize, const RX_SZ: usize> embedded_io::asynch::Read
+        for TcpConnection<'d, N, TX_SZ, RX_SZ>
+    {
+        type ReadFuture<'a> = impl Future<Output = Result<usize, Self::Error>>
+    where
+        Self: 'a;
+
+        fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Self::ReadFuture<'a> {
+            self.socket.read(buf)
+        }
+    }
+
+    impl<'d, const N: usize, const TX_SZ: usize, const RX_SZ: usize> embedded_io::asynch::Write
+        for TcpConnection<'d, N, TX_SZ, RX_SZ>
+    {
+        type WriteFuture<'a> = impl Future<Output = Result<usize, Self::Error>>
+    where
+        Self: 'a;
+
+        fn write<'a>(&'a mut self, buf: &'a [u8]) -> Self::WriteFuture<'a> {
+            self.socket.write(buf)
+        }
+
+        type FlushFuture<'a> = impl Future<Output = Result<(), Self::Error>>
+    where
+        Self: 'a;
+
+        fn flush<'a>(&'a mut self) -> Self::FlushFuture<'a> {
+            self.socket.flush()
+        }
+    }
+
+    pub type BufferPool<const BUFSZ: usize, const N: usize> = Pool<[u8; BUFSZ], N>;
+
+    pub struct Pool<T, const N: usize> {
+        used: [AtomicBool; N],
+        data: [UnsafeCell<MaybeUninit<T>>; N],
+    }
+
+    impl<T, const N: usize> Pool<T, N> {
+        const VALUE: AtomicBool = AtomicBool::new(false);
+        const UNINIT: UnsafeCell<MaybeUninit<T>> = UnsafeCell::new(MaybeUninit::uninit());
+
+        pub const fn new() -> Self {
+            Self {
+                used: [Self::VALUE; N],
+                data: [Self::UNINIT; N],
+            }
+        }
+    }
+
+    impl<T, const N: usize> Pool<T, N> {
+        fn alloc(&self) -> Option<NonNull<T>> {
+            for n in 0..N {
+                if self.used[n].swap(true, Ordering::SeqCst) == false {
+                    let p = self.data[n].get() as *mut T;
+                    return Some(unsafe { NonNull::new_unchecked(p) });
+                }
+            }
+            None
+        }
+
+        /// safety: p must be a pointer obtained from self.alloc that hasn't been freed yet.
+        unsafe fn free(&self, p: NonNull<T>) {
+            let origin = self.data.as_ptr() as *mut T;
+            let n = p.as_ptr().offset_from(origin);
+            assert!(n >= 0);
+            assert!((n as usize) < N);
+            self.used[n as usize].store(false, Ordering::SeqCst);
+        }
+    }
+}
diff --git a/examples/stm32h7/Cargo.toml b/examples/stm32h7/Cargo.toml
index 8b1999b30..07b7e4931 100644
--- a/examples/stm32h7/Cargo.toml
+++ b/examples/stm32h7/Cargo.toml
@@ -7,7 +7,7 @@ version = "0.1.0"
 embassy-util = { version = "0.1.0", path = "../../embassy-util", features = ["defmt"] }
 embassy-executor = { version = "0.1.0", path = "../../embassy-executor", features = ["defmt", "defmt-timestamp-uptime", "unstable-traits", "time-tick-32768hz"] }
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "stm32h743bi", "net", "time-driver-any", "exti", "unstable-pac", "unstable-traits"] }
-embassy-net = { path = "../../embassy-net", features = ["defmt", "tcp", "dhcpv4", "medium-ethernet", "pool-16"] }
+embassy-net = { path = "../../embassy-net", features = ["defmt", "tcp", "dhcpv4", "medium-ethernet", "pool-16", "unstable-traits"] }
 embedded-io = { version = "0.3.0", features = ["async"] }
 
 defmt = "0.3"