Question

Is it possible to check if the client socket is keeping connection alive at the moment? I use multithread server that use AsyncCallBack operations.
There is a lot of similar questions about this issue and I’ve read about Socket.Poll method – everything doesn’t work properly.

Tried to apply this sample:

    bool IsConnectedAviable(Socket s)
    {
        try
        {
            if (s != null && s.Connected)
            {
                if (s.Poll(0, SelectMode.SelectRead))
                {
                    byte[] buff = new byte[1];
                    if (s.Receive(buff, SocketFlags.Peek) == 0)
                    {
                        return false;
                    }
                    else
                    {
                        return true;
                    }
                }

                return true;
            }
            else
            {
                return false;
            }
        }
        catch
        {
            return false;
        }
    }

Thanks in advance! 🙂

Answer 1

If you receive something from the other end, you know the connection is still alive. If you don’t receive anything from the other end for a while, the only way to determine if the connection is still alive is by sending something.