public Try <bool> Send(byte unitId, List <byte> adu)
{
if (!_socket.Connected)
{
return(Try.Failure <bool>(new SocketException((int)SocketError.NotConnected)));
}
if (_socket.Poll(0, SelectMode.SelectRead))
{
/* at this point we assume that there can't be anything to read,
* so socket received FINACK some time ago
* http://stackoverflow.com/questions/23665917/is-it-possible-to-detect-if-a-socket-is-in-the-close-wait-state/ */
_socket.Close();
return(Try.Failure <bool>(new SocketException((int)SocketError.NotConnected)));
}
async Task <int> send(ArraySegment <byte> segment) => await _socket.SendAsync(segment, SocketFlags.None);
var result =
from pdu in Try.Apply(() => new ArraySegment <byte>(MbHelpers.PrependMbapHeader(unitId, _transactionId, adu).ToArray()))
from snd in Try.Apply(() => { var sent = send(pdu); sent.Wait(); return(sent.Result); })
select snd == pdu.Count;
// TODO: check for exceptions and so on....
return(result);
}
public Try <List <byte> > Receive(byte expectedUnitId)
{
if (!_socket.Connected)
{
return(Try.Failure <List <byte> >(new SocketException((int)SocketError.NotConnected)));
}
var buffer = new List <byte>();
async Task receive()
{
do
{
var segment = new ArraySegment <byte>(new byte[512]);
var received = await _socket.ReceiveAsync(segment, SocketFlags.None);
buffer.AddRange(segment.Array.Take(received));
} while (_socket.Available != 0);
}
bool rectimeout = false;
async Task receiveWithTimeout() => await Task.WhenAny(receive(), Task.Delay(_timeout).ContinueWith(
t => rectimeout = true));
var result =
from rec in Try.Apply(() => receiveWithTimeout().Wait())
from res in Try.Apply(() =>
{
if (rectimeout)
{
_socket.Close();
throw new SocketException((int)SocketError.TimedOut);
}
if (buffer.Count == 0)
{
_socket.Close();
throw new SocketException((int)SocketError.NotConnected);
}
(var transId, var unitId, var pdu) = MbHelpers.UnwrapMbapHeader(buffer);
if (transId != _transactionId)
{
var message = $"Sent transaction id {_transactionId}, received {transId}. Dropping response.";
_logger.Debug(message);
throw new Exception(message);
}
if (unitId != expectedUnitId)
{
var message = $"Sent unit id {expectedUnitId}, received {unitId}. Dropping response.";
_logger.Debug(message);
throw new Exception(message);
}
return(pdu);
})
select res;
NextTransaction();
return(result);
}
