public Task <int> ReceiveAsync(ArraySegment <byte> buffer, CancellationToken cancellationToken)
{
if (buffer.Array == null)
{
throw new ArgumentNullException(nameof(buffer));
}
cancellationToken.ThrowIfCancellationRequested();
using (cancellationToken.Register(() => _udpTransport.Close()))
{
try
{
var received = _dtlsTransport.Receive(buffer.Array, buffer.Offset, buffer.Count, 0);
return(Task.FromResult(received));
}
catch (ObjectDisposedException)
{
return(Task.FromResult(0));
}
catch (SocketException)
{
return(Task.FromResult(0));
}
}
}
public async Task ConnectAsync(CoapTransportLayerConnectOptions connectOptions, CancellationToken cancellationToken)
{
if (connectOptions == null)
{
throw new ArgumentNullException(nameof(connectOptions));
}
cancellationToken.ThrowIfCancellationRequested();
try
{
_udpTransport = new UdpTransport(connectOptions);
var clientProtocol = new DtlsClientProtocol(_secureRandom);
_dtlsClient = new DtlsClient(ConvertProtocolVersion(DtlsVersion), (PreSharedKey)Credentials);
using (cancellationToken.Register(() =>
{
_udpTransport.Close();
}))
{
_dtlsTransport = await Task.Run(() => clientProtocol.Connect(_dtlsClient, _udpTransport), cancellationToken).ConfigureAwait(false);
}
}
catch
{
_udpTransport?.Dispose();
if (cancellationToken.IsCancellationRequested)
{
throw new OperationCanceledException();
}
if (_dtlsClient.ReceivedAlert != 0)
{
throw new DtlsException($"Received alert {AlertDescription.GetText(_dtlsClient.ReceivedAlert)}.", null)
{
ReceivedAlert = _dtlsClient.ReceivedAlert
};
}
throw;
}
}