/// <summary>
/// Connects to a service on a device.
/// </summary>
/// <param name="device">
/// The device to which to connect.
/// </param>
/// <param name="port">
/// The TCP port number to which to connect.
/// </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken"/> which can be used to cancel the asynchronous task.
/// </param>
/// <returns>
/// A <see cref="Task"/> which represents the asynchronous operation, and which returns a <see cref="Stream"/>
/// which represents the connection with the device. You must dispose of this stream when you are done with it.
/// </returns>
public virtual async Task <Stream> ConnectAsync(MuxerDevice device, int port, CancellationToken cancellationToken)
{
var(error, stream) = await this.TryConnectAsync(device, port, cancellationToken).ConfigureAwait(false);
if (error != MuxerError.Success)
{
// If you get error 2 (BadDevice) here, you're too late: the service has been shut
// down because you didn't connect in time.
throw new MuxerException(
$"The device returned an invalid response number when connecting. Expected Success but got {error}",
error);
}
return(stream);
}
/// <summary>
/// Attempts to connect to a service on a device.
/// </summary>
/// <param name="device">
/// The device to which to connect.
/// </param>
/// <param name="port">
/// The TCP port number to which to connect.
/// </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken"/> which can be used to cancel the asynchronous task.
/// </param>
/// <returns>
/// A <see cref="Task"/> which represents the asynchronous operation, and which returns a <see cref="Stream"/>
/// which represents the connection with the device. You must dispose of this stream when you are done with it.
/// </returns>
public virtual async Task <(MuxerError, Stream)> TryConnectAsync(MuxerDevice device, int port, CancellationToken cancellationToken)
{
if (device == null)
{
throw new ArgumentNullException(nameof(device));
}
var bigEndianPort = unchecked ((ushort)((port >> 8 & 0xFF) | (port & 0xFF) << 8));
var protocol = await this.TryConnectToMuxerAsync(cancellationToken).ConfigureAwait(false);
if (protocol == null)
{
this.logger.LogWarning("Could not connect to the server.");
return(MuxerError.MuxerError, null);
}
// Send the connect request to the muxer.
await protocol.WriteMessageAsync(
new ConnectMessage()
{
DeviceID = device.DeviceID,
PortNumber = bigEndianPort,
MessageType = MuxerMessageType.Connect,
},
cancellationToken).ConfigureAwait(false);
// Read the response
var response = await protocol.ReadMessageAsync(cancellationToken).ConfigureAwait(false);
if (response == null)
{
this.logger.LogWarning("The server unexpectedly close the connection when sending the Connect command.");
return(MuxerError.MuxerError, null);
}
var result = (ResultMessage)response;
if (result.Number != MuxerError.Success)
{
return(result.Number, null);
}
// The muxer will now forward all messages to the service listening at the port specified on the device.
// The caller can use this stream (but must dispose of it).
return(result.Number, protocol.Stream);
}