nal: Fix read/write not pushing erroneous socket back to the stack

* Based on quartiq's minimq as of 933687c2e4
* In minimq applications, a socket is expected to be returned when `nal::TcpStack::open()` is called
  * `MqttClient::read()`/`write()` takes away the TCP socket handle (wrapped as an `Option`) from its `RefCell`, and then calls `nal::TcpStack::read()`/`write()`; if NAL returns `nb::Error`, then the MQTT client will propagate and return the error, leaving `None` behind
  * Afterwards, when `MqttClient::socket_is_connected()` gets called (e.g. while polling the interface), it will detect that the socket handle is `None`, and attempt to call `nal::TcpStack::open()`
  * Since `open()` pops a socket from the array (`unused_handles`), when implementing this NAL the socket should have been pushed back to the stack, i.e. by `close()`; this prevents any future calls of `open()` from returning `NetworkError::NoSocket` due to emptiness of the array of socket handles
This commit is contained in:
Harry Ho 2021-03-11 17:15:39 +08:00
parent d9e50bbcb6
commit 99899e6657

View File

@ -236,6 +236,7 @@ where
}
fn write(&self, socket: &mut Self::TcpSocket, buffer: &[u8]) -> nb::Result<usize, Self::Error> {
let mut write_error = false;
let mut non_queued_bytes = &buffer[..];
while non_queued_bytes.len() != 0 {
let result = {
@ -254,9 +255,18 @@ where
// Process the unwritten bytes again, if any
non_queued_bytes = &non_queued_bytes[num_bytes..]
}
Err(_) => return Err(nb::Error::Other(NetworkError::WriteFailure)),
Err(_) => {
write_error = true;
break;
}
}
}
if write_error {
// Close the socket to push it back to the array, for
// re-opening the socket in the future
self.close(*socket)?;
return Err(nb::Error::Other(NetworkError::WriteFailure))
}
Ok(buffer.len())
}
@ -268,13 +278,19 @@ where
// Enqueue received bytes into the TCP socket buffer
self.update()?;
self.poll()?;
let mut sockets = self.sockets.borrow_mut();
let socket: &mut net::socket::TcpSocket = &mut *sockets.get(*socket);
let result = socket.recv_slice(buffer);
match result {
Ok(num_bytes) => Ok(num_bytes),
Err(_) => Err(nb::Error::Other(NetworkError::ReadFailure)),
{
let mut sockets = self.sockets.borrow_mut();
let socket: &mut net::socket::TcpSocket = &mut *sockets.get(*socket);
let result = socket.recv_slice(buffer);
match result {
Ok(num_bytes) => { return Ok(num_bytes) },
Err(_) => {},
}
}
// Close the socket to push it back to the array, for
// re-opening the socket in the future
self.close(*socket)?;
Err(nb::Error::Other(NetworkError::ReadFailure))
}
fn close(&self, socket: Self::TcpSocket) -> Result<(), Self::Error> {