C＃NetworkStream不会引发异常

Question

I am writing a simple C# server and client , but it doesn't throw an exception when the client is disconnected. It will continue reading from the client, thinking that the client is still there. It also no longer blocks when the client is gone. I expect it to throw an exception if the client is no longer available.

private TcpListener server;
private NetworkStream stream;
private TcpClient client;
private byte[] buffer = new byte[1];

server = new TcpListener (serverIp, _portNumber);
server.Start();

stream = client.GetStream();

//The part I want to throw exception when the client is gone but doesn't.

try
{
    stream.Read(buffer,0,1);
}
catch(Exception e)
{
    #if (DEBUG)
    Debug.Log ("Failed Rading " + e.Message);
    #endif
    return 0; 
}

Any help would be appreciated.

Answer 1

It should throw an exception when the connection is closed and there is no more data in the buffer to read. Apparently there is still data available. When the buffer and the connection is closed you should get an exception. Also I see you read data 1 byte at the time. Why not first check if the connection is alive:

client.Client.Poll(0, SelectMode.SelectRead)

check if there is data available to read and read the correct amount:

int available = client.Client.Available;
if(available > 0)
{
   var buffer = new byte[available];
   client.Read(buffer, 0, available);
}

Answer 2

If the client goes away without notifying the server there is nothing you can do except timeout. The server has no way of finding out the fact that the client is gone.

You need to live with this fact. Set a timeout.