Question

        NetworkStream stream = socket.GetStream();

        if (stream.CanRead)
        {
            while (true)
            {
                int i = stream.Read(buf, 0, 1024);
                result += Encoding.ASCII.GetString(buf, 0, i);
            }
        }

Above code was designed to retrieve message from a TcpClient while running on a separate thread. Read Method works fine until it is supposed to return -1 to indicate there is nothing to read anymore; instead, it just terminates the thread it is running on without any apparent reason – tracing each step using the debugger shows that it just stops running right after that line.

Also I tried encapsulating it with a try ... catch without much success.

What could be causing this?

EDIT: I tried

        NetworkStream stream = socket.GetStream();

    if (stream.CanRead)
    {
        while (true)
        {
            int i = stream.Read(buf, 0, 1024);
            if (i == 0)
            {
                break;
            }
            result += Encoding.ASCII.GetString(buf, 0, i);
        }
    }

thanks to @JonSkeet, but the problem is still there. The thread terminates at that read line.

EDIT2: I fixed the code like this and it worked.

    while (stream.DataAvailable)
    {
        int i = stream.Read(buf, 0, 1024);
        result += Encoding.ASCII.GetString(buf, 0, i);
    }

I think the problem was simple, I just didn’t think thoroughly enough. Thanks everyone for taking a look at this!

Answer 1

It looks to me like it is simply blocking – i.e. waiting on the end of the stream. For it to return a non-positive number, it is necessary that the stream be closed, i.e. the the caller has not only sent data, but has closed their outbound socket. Otherwise, the system cannot distinguish between “waiting for a packet to arrive” and “the end of the stream”.

If the caller is sending one message only, they should close their outbound socket after sending (they can keep their inbound socket open for a reply).

If the caller is sending multiple messages, then you must use a framing approach to read individual sub-messages. In the case of a text-based protocol this usually means “hunt the newline”.