Question

I have an application using which I execute IMAP commands using:

• TcpClient to connect to the IMAP server
• SslStream to write and read commands

Problem:

• Cannot read the complete ouput content from the stream
• while loop on the SslStream.Read seems not to work
• StreamReader.ReadLine, ReadToEnd, Read methods do not work

Sample code:

while ((l = reader.ReadLine()) != null)
{
    output.AppendLine(l);
}

This code snippet would read 1 to 2 lines and hang in reader.Readline().

Workaround I tried with setting the ReadTimeout property:

try
{
    _output=new byte[_tcpclient.ReceiveBufferSize];
    _sslstream.Read(_output, 0, _output.Length);
    textBox1.Text = Encoding.ASCII.GetString(_output);
}
catch (IOException ex)
{
    textBox1.Text ="ERROR !! " + ex.Message;                
}

Help:

• How can I read the complete output of a command from the stream?

Note: I do not want to use any third party libraries.

Answer 1

The TCP stream cannot know whether the current response has finished. All it knows is whether it has just received data on the wire; it cannot know whether the next packet is going to come right now (a multi-packet response) or whether it will come much later (if the response is finished).

Instead, you need to predict when you’ll get more data; you should keep reading until you receive a tagged completion response, as documented in the IMAP protocol.

However, IMAP seems to be intended to be read continuously on a background thread, since the server can send you information at any time. Therefore, you probably ought to have a separate thread which is always in ReadLine().