通过Socket.SetSocketOption()实现TCP/IP KeepAlive机制(C#)

Using TCP/IP KeepAlive in C#

I have been trying to make NetSocket.SetSocketOption work for TCP/IP KeepAlive

I have tried the following code

public virtual void SetKeepAlive(ulong keepalive_time, ulong keepalive_interval)
        {
            int bytes_per_long = 32 / 8;
            byte[] keep_alive = new byte[3 * bytes_per_long];
            ulong[] input_params = new ulong[3];
            int i1;
            int bits_per_byte = 8;

            if (keepalive_time == 0 || keepalive_interval == 0)
                input_params[0] = 0;
            else
                input_params[0] = 1;
            input_params[1] = keepalive_time;
            input_params[2] = keepalive_interval;
            for (i1 = 0; i1 < input_params.Length; i1++)
            {
                keep_alive[i1 * bytes_per_long + 3] = (byte)(input_params[i1] >> ((bytes_per_long - 1) * bits_per_byte) & 0xff);
                keep_alive[i1 * bytes_per_long + 2] = (byte)(input_params[i1] >> ((bytes_per_long - 2) * bits_per_byte) & 0xff);
                keep_alive[i1 * bytes_per_long + 1] = (byte)(input_params[i1] >> ((bytes_per_long - 3) * bits_per_byte) & 0xff);
                keep_alive[i1 * bytes_per_long + 0] = (byte)(input_params[i1] >> ((bytes_per_long - 4) * bits_per_byte) & 0xff);
            }
            LogTrace.Trace(this, "Keep Alive Bits: {0}", ByteArrayFormater.HexDump(keep_alive));
            NetSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.KeepAlive, keep_alive);
        } /* method AsyncSocket SetKeepAlive */

The result is not error, no exception and no keepalive in the expected time frame.
I am passing both times in mill-seconds. The Trace that I have shows 12 bytes in the form of
01 00 00 00 10 27 00 00 98 3a 00 00 when called as SetKeepAlive(10000,15000);

I am not really sure if I need to put the bytes in this order or not. If working directly with the Winsock API, the keepalive
option uses a structure of 3 ULONGS with a 1 in the first one, the time in the 2nd one and the retry time (interval in this code)
in the third one.

另外，通过Socket.IOControl()也可以实现这种机制：http://blog.csdn.net/kenkao/archive/2010/03/25/5415159.aspx