/// <summary>
/// Opens the connection. This includes the hello message handshake.
/// </summary>
/// <remakes>
/// The underlying network client is already opened before this class is
/// constructed. The
/// connection is closed with <see cref="IAsyncDisposable.DisposeAsync"/>
/// method.
/// </remakes>
/// <param name="protocolVersion">The protocol version.</param>
/// <param name="localOptions">The requested transport connection options.</param>
/// <param name="token">A cancellation token used to propagate notification that this operation should be canceled.</param>
/// <returns>The transport connection options to be used.</returns>
/// <seealso href="https://reference.opcfoundation.org/v104/Core/docs/Part6/7.1.2/">OPC UA specification Part 6: Mappings, 7.1.2</seealso>
public async Task <TransportConnectionOptions> OpenAsync(uint protocolVersion, TransportConnectionOptions localOptions, CancellationToken token)
{
var sendBuffer = new byte[MinBufferSize];
var receiveBuffer = new byte[MinBufferSize];
// send 'hello'.
int count;
using (var encoder = new BinaryEncoder(new MemoryStream(sendBuffer, 0, MinBufferSize, true, false)))
{
encoder.WriteUInt32(null, MessageTypes.HELF);
encoder.WriteUInt32(null, 0u);
encoder.WriteUInt32(null, protocolVersion);
encoder.WriteUInt32(null, localOptions.ReceiveBufferSize);
encoder.WriteUInt32(null, localOptions.SendBufferSize);
encoder.WriteUInt32(null, localOptions.MaxMessageSize);
encoder.WriteUInt32(null, localOptions.MaxChunkCount);
encoder.WriteString(null, Uri.ToString());
count = encoder.Position;
encoder.Position = 4;
encoder.WriteUInt32(null, (uint)count);
encoder.Position = count;
await SendAsync(sendBuffer, 0, count, token).ConfigureAwait(false);
}
// receive response
count = await ReceiveAsync(receiveBuffer, 0, MinBufferSize, token).ConfigureAwait(false);
if (count == 0)
{
throw new ObjectDisposedException("socket");
}
// decode 'ack' or 'err'.
using (var decoder = new BinaryDecoder(new MemoryStream(receiveBuffer, 0, count, false, false)))
{
var type = decoder.ReadUInt32(null);
var len = decoder.ReadUInt32(null);
if (type == MessageTypes.ACKF)
{
var remoteProtocolVersion = decoder.ReadUInt32(null);
if (remoteProtocolVersion < protocolVersion)
{
throw new ServiceResultException(StatusCodes.BadProtocolVersionUnsupported);
}
var remoteOptions = new TransportConnectionOptions
{
SendBufferSize = decoder.ReadUInt32(null),
ReceiveBufferSize = decoder.ReadUInt32(null),
MaxMessageSize = decoder.ReadUInt32(null),
MaxChunkCount = decoder.ReadUInt32(null)
};
return(remoteOptions);
}
else if (type == MessageTypes.ERRF)
{
var statusCode = decoder.ReadUInt32(null);
var message = decoder.ReadString(null);
if (message != null)
{
throw new ServiceResultException(statusCode, message);
}
throw new ServiceResultException(statusCode);
}
throw new InvalidOperationException($"{nameof(UaClientConnection)}.{nameof(OpenAsync)} received unexpected message type.");
}
}
protected override async Task OnOpenAsync(CancellationToken token)
{
token.ThrowIfCancellationRequested();
this.sendBuffer = new byte[MinBufferSize];
this.receiveBuffer = new byte[MinBufferSize];
this.tcpClient = new TcpClient {
NoDelay = true
};
var uri = new UriBuilder(this.RemoteEndpoint.EndpointUrl);
await this.tcpClient.ConnectAsync(uri.Host, uri.Port).ConfigureAwait(false);
this.stream = this.tcpClient.GetStream();
// send 'hello'.
int count;
var encoder = new BinaryEncoder(new MemoryStream(this.sendBuffer, 0, MinBufferSize, true, false));
try
{
encoder.WriteUInt32(null, UaTcpMessageTypes.HELF);
encoder.WriteUInt32(null, 0u);
encoder.WriteUInt32(null, ProtocolVersion);
encoder.WriteUInt32(null, this.LocalReceiveBufferSize);
encoder.WriteUInt32(null, this.LocalSendBufferSize);
encoder.WriteUInt32(null, this.LocalMaxMessageSize);
encoder.WriteUInt32(null, this.LocalMaxChunkCount);
encoder.WriteString(null, uri.ToString());
count = encoder.Position;
encoder.Position = 4;
encoder.WriteUInt32(null, (uint)count);
encoder.Position = count;
await this.SendAsync(this.sendBuffer, 0, count, token).ConfigureAwait(false);
}
finally
{
encoder.Dispose();
}
// receive response
count = await this.ReceiveAsync(this.receiveBuffer, 0, MinBufferSize, token).ConfigureAwait(false);
if (count == 0)
{
throw new ObjectDisposedException("socket");
}
// decode 'ack' or 'err'.
var decoder = new BinaryDecoder(new MemoryStream(this.receiveBuffer, 0, count, false, false));
try
{
var type = decoder.ReadUInt32(null);
var len = decoder.ReadUInt32(null);
if (type == UaTcpMessageTypes.ACKF)
{
var remoteProtocolVersion = decoder.ReadUInt32(null);
if (remoteProtocolVersion < ProtocolVersion)
{
throw new ServiceResultException(StatusCodes.BadProtocolVersionUnsupported);
}
this.RemoteSendBufferSize = decoder.ReadUInt32(null);
this.RemoteReceiveBufferSize = decoder.ReadUInt32(null);
this.RemoteMaxMessageSize = decoder.ReadUInt32(null);
this.RemoteMaxChunkCount = decoder.ReadUInt32(null);
return;
}
else if (type == UaTcpMessageTypes.ERRF)
{
var statusCode = decoder.ReadUInt32(null);
var message = decoder.ReadString(null);
if (message != null)
{
throw new ServiceResultException(statusCode, message);
}
throw new ServiceResultException(statusCode);
}
throw new InvalidOperationException("UaTcpTransportChannel.OnOpenAsync received unexpected message type.");
}
finally
{
decoder.Dispose();
}
}