Add async send and recv functions to AsyncSession

src/async_session.rs

@@ -57,6 +57,33 @@ impl AsyncSession {
             e => panic!("WaitForMultipleObjects returned unexpected value {:?}", e),
         }
     }
+
+    pub async fn recv(&self, buf: &mut [u8]) -> std::io::Result<usize> {
+        loop {
+            match self.session.try_receive() {
+                Ok(Some(packet)) => {
+                    // it seems to be standard practice to truncate rather than return an error,
+                    // in the context of TUN/TAP the packet lengths can be read anyway
+                    let size = packet.bytes.len().min(buf.len());
+                    buf[..size].copy_from_slice(&packet.bytes[..size]);
+                    return Ok(size);
+                }
+                Ok(None) => {
+                    let read_event = self.session.get_read_wait_event()?;
+                    let shutdown_event = self.session.shutdown_event.get_handle();
+                    blocking::unblock(move || Self::wait_for_read(read_event, shutdown_event)).await;
+                }
+                Err(err) => return Err(std::io::Error::new(std::io::ErrorKind::Other, err)),
+            }
+        }
+    }
+
+    pub async fn send(&self, buf: &[u8]) -> std::io::Result<usize> {
+        let packet = self.session.allocate_send_packet(buf.len() as _)?;
+        packet.bytes.copy_from_slice(buf);
+        self.session.send_packet(packet);
+        Ok(buf.len())
+    }
 }
 
 impl AsyncRead for AsyncSession {