src/transport/mod.rs

@@ -5,6 +5,7 @@
 //! something like CCSDS space packets over different transport mechanisms.
 pub mod serial;
 pub mod tcp;
+pub mod udp;
 
 /// Generic send error.
 #[derive(Debug, thiserror::Error)]

src/transport/tcp.rs

@@ -7,6 +7,8 @@ use std::{
 use crate::transport::PacketTransport;
 
 /// Packet transport via TCP with COBS encoding.
+///
+/// Currently only allows a maxium packet size of 4096.
 pub struct PacketTransportTcpWithCobs {
     /// Underlying TCP stream.
     pub tcp_stream: std::net::TcpStream,
@@ -14,7 +16,7 @@ pub struct PacketTransportTcpWithCobs {
     pub log_decoding_errors: bool,
     /// Decoder object.
     decoder: cobs::CobsDecoderOwned,
-    reception_buffer: [u8; 1024],
+    reception_buffer: [u8; 4096],
 }
 
 impl PacketTransportTcpWithCobs {
@@ -30,7 +32,7 @@ impl PacketTransportTcpWithCobs {
         Ok(Self {
             tcp_stream,
             decoder,
-            reception_buffer: [0u8; 1024],
+            reception_buffer: [0u8; 4096],
             log_decoding_errors: true,
         })
     }

src/transport/udp.rs

@@ -0,0 +1,175 @@
+//! # Packet transport via UDP
+
+use std::io::ErrorKind;
+
+use crate::transport::PacketTransport;
+
+/// Generic packet transport via UDP.
+///
+/// Currently only allows a maxium packet size of 4096.
+pub struct PacketTransportUdp {
+    /// Underlying UDP socket.
+    pub socket: std::net::UdpSocket,
+    reception_buffer: [u8; 4096],
+}
+
+impl PacketTransportUdp {
+    /// Generic constructor.
+    ///
+    /// The `socket` parameter is the underlying UDP stream which should already be connected.
+    /// It will be set non-blocking by the construtor.
+    pub fn new(socket: std::net::UdpSocket) -> Result<Self, std::io::Error> {
+        socket.set_nonblocking(true)?;
+        Ok(Self {
+            socket,
+            reception_buffer: [0u8; 4096],
+        })
+    }
+}
+
+impl PacketTransport for PacketTransportUdp {
+    fn send(&mut self, packet: &[u8]) -> Result<(), super::SendError> {
+        self.socket.send(packet).map_err(super::SendError::Io)?;
+        Ok(())
+    }
+
+    fn receive<F: FnMut(&[u8])>(&mut self, mut f: F) -> Result<usize, super::ReceiveError> {
+        let mut packets_received = 0;
+        loop {
+            match self.socket.recv_from(&mut self.reception_buffer) {
+                Ok((bytes, _)) => {
+                    packets_received += 1;
+                    f(&self.reception_buffer[..bytes]);
+                }
+                Err(e) => {
+                    if e.kind() == ErrorKind::WouldBlock || e.kind() == ErrorKind::TimedOut {
+                        break;
+                    }
+                    log::error!("UDP reception error: {e}");
+                }
+            }
+        }
+        Ok(packets_received)
+    }
+
+    fn close(&mut self) {}
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn basic_send_test() {
+        let receiver = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+        let sender = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+
+        let receiver_addr = receiver.local_addr().unwrap();
+        sender.connect(receiver_addr).unwrap();
+
+        let mut transport = PacketTransportUdp::new(sender).unwrap();
+        let payload = [1u8, 2, 3, 4];
+
+        transport.send(&payload).unwrap();
+
+        let mut buf = [0u8; 16];
+        let (len, from) = receiver.recv_from(&mut buf).unwrap();
+
+        assert_eq!(&buf[..len], &payload);
+        assert_eq!(from, transport.socket.local_addr().unwrap());
+    }
+
+    #[test]
+    fn receive_is_non_blocking_when_no_data_is_available() {
+        let receiver = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+        let mut transport = PacketTransportUdp::new(receiver).unwrap();
+
+        let start = std::time::Instant::now();
+        let mut callback_called = false;
+
+        let packets_received = transport
+            .receive(|_| {
+                callback_called = true;
+            })
+            .unwrap();
+
+        let elapsed = start.elapsed();
+
+        assert_eq!(packets_received, 0);
+        assert!(!callback_called);
+        assert!(
+            elapsed < std::time::Duration::from_millis(50),
+            "receive() took too long for a non-blocking socket: {:?}",
+            elapsed
+        );
+    }
+
+    #[test]
+    fn basic_receive_test_single() {
+        let receiver = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+        let sender = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+
+        let receiver_addr = receiver.local_addr().unwrap();
+        sender.send_to(&[1u8, 2, 3, 4], receiver_addr).unwrap();
+
+        let mut transport = PacketTransportUdp::new(receiver).unwrap();
+
+        let mut received_packets: Vec<Vec<u8>> = Vec::new();
+        let packets_received = transport
+            .receive(|packet| received_packets.push(packet.to_vec()))
+            .unwrap();
+
+        assert_eq!(packets_received, 1);
+        assert_eq!(received_packets.len(), 1);
+        assert_eq!(received_packets[0], vec![1u8, 2, 3, 4]);
+    }
+
+    #[test]
+    fn multi_packet_receive_test() {
+        let receiver = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+        let sender = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+
+        let receiver_addr = receiver.local_addr().unwrap();
+        sender.send_to(&[1u8, 2, 3, 4], receiver_addr).unwrap();
+        sender.send_to(&[5u8, 6, 7, 8], receiver_addr).unwrap();
+        sender.send_to(&[9u8, 10, 11, 12], receiver_addr).unwrap();
+
+        let mut transport = PacketTransportUdp::new(receiver).unwrap();
+
+        let mut received_packets: Vec<Vec<u8>> = Vec::new();
+        let packets_received = transport
+            .receive(|packet| received_packets.push(packet.to_vec()))
+            .unwrap();
+
+        assert_eq!(packets_received, 3);
+        assert_eq!(received_packets.len(), 3);
+        assert_eq!(received_packets[0], vec![1u8, 2, 3, 4]);
+        assert_eq!(received_packets[1], vec![5u8, 6, 7, 8]);
+        assert_eq!(received_packets[2], vec![9u8, 10, 11, 12]);
+    }
+
+    #[test]
+    fn send_and_receive_test() {
+        let receiver = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+        let sender = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+
+        let receiver_addr = receiver.local_addr().unwrap();
+        sender.connect(receiver_addr).unwrap();
+
+        let mut send_transport = PacketTransportUdp::new(sender).unwrap();
+        let payload = [1u8, 2, 3, 4];
+
+        send_transport.send(&payload).unwrap();
+
+        let mut receive_transport = PacketTransportUdp::new(receiver).unwrap();
+        let mut received_packets: Vec<Vec<u8>> = Vec::new();
+
+        let packets_received = receive_transport
+            .receive(|packet| received_packets.push(packet.to_vec()))
+            .unwrap();
+
+        assert_eq!(packets_received, 1);
+        assert_eq!(received_packets.len(), 1);
+        assert_eq!(received_packets[0], payload.to_vec());
+    }
+}