I am connecting to a remote Telnet Server using TcpClient and Networkstream, as long as the expected answer is delivered from the server everything works fine – however I would like to add a timeout, to catch an exception.

That’s my current code, where I am waiting for “Username”

byte[] buffer = new byte[4096];

string response = "";
int bytesRead;

var cancellationTokenSource = new CancellationTokenSource();
cancellationTokenSource.CancelAfter(5000); //does not work as timeout

while (!response.Contains("Username"))
{
    try
    {
        bytesRead = await targetClient.GetStream().ReadAsync(buffer, 0, buffer.Length, cancellationTokenSource.Token);
        response += Encoding.ASCII.GetString(buffer, 0, bytesRead);
        Console.WriteLine($"Answer from Telnet-Server: {response}");
    }
    catch
    {
        Console.WriteLine("catch");
        break;
    }
}

If I understand the ReadAsync function right – the cancellationToken is not taken into Account – so that’s not how a timeout could be added.

Is there any possibility to add a timeout? Maybe some second Workerthread, which fires after 5 Seconds, and if the response does not contain “Username” I break out of the while loop?
Or should I change the ReadAsync do a Synchronous Method, which supports a timeout?
Or should I read everything from the Telnet Server into a Queue, and only ask if the Queue contains a relevant keyword, like “Username”, would that be possible?

But I think there are much better approaches, right?

Thanks