C# ping操作，MSDN版（不是socket自己写值的版本）

class PingClass {

        private static long ms = -1;

        public static long ping(string ip) {

            AutoResetEvent waiter = new AutoResetEvent(false);

            Ping pingSender = new Ping();

            // When the PingCompleted event is raised,

            // the PingCompletedCallback method is called.

            pingSender.PingCompleted += new PingCompletedEventHandler(PingCompletedCallback);

            // Create a buffer of 32 bytes of data to be transmitted.

            string data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";

            byte[] buffer = Encoding.ASCII.GetBytes(data);

            // Wait 12 seconds for a reply.

            int timeout = 2000;

            // Set options for transmission:

            // The data can go through 64 gateways or routers

            // before it is destroyed, and the data packet

            // cannot be fragmented.

            PingOptions options = new PingOptions(64, true);

            //Console.WriteLine("Time to live: {0}", options.Ttl);

            //Console.WriteLine("Don't fragment: {0}", options.DontFragment);

            // Send the ping asynchronously.

            // Use the waiter as the user token.

            // When the callback completes, it can wake up this thread.

            pingSender.SendAsync(ip, timeout, buffer, options, waiter);

            // Prevent this example application from ending.

            // A real application should do something useful

            // when possible.

            waiter.WaitOne();

            //Console.WriteLine("Ping example completed.");

            return ms;

        }

        private static void PingCompletedCallback(object sender, PingCompletedEventArgs e) {

            // If the operation was canceled, display a message to the user.

            if (e.Cancelled) {

                Console.WriteLine("Ping canceled.");

                // Let the main thread resume. 

                // UserToken is the AutoResetEvent object that the main thread 

                // is waiting for.

                ((AutoResetEvent)e.UserState).Set();

            }

            // If an error occurred, display the exception to the user.

            if (e.Error != null) {

                //Console.WriteLine("Ping failed:");

                //Console.WriteLine(e.Error.ToString());

                // Let the main thread resume. 

                ((AutoResetEvent)e.UserState).Set();

            }

            PingReply reply = e.Reply;

            DisplayReply(reply);

            // Let the main thread resume.

            ((AutoResetEvent)e.UserState).Set();

        }

        public static void DisplayReply(PingReply reply) {

            if (reply == null)

                return;

            //Console.WriteLine("ping status: {0}", reply.Status);

            if (reply.Status == IPStatus.Success) {

                //Console.WriteLine("Address: {0}", reply.Address.ToString());

                //Console.WriteLine("RoundTrip time: {0}", reply.RoundtripTime);

                //Console.WriteLine("Time to live: {0}", reply.Options.Ttl);

                //Console.WriteLine("Don't fragment: {0}", reply.Options.DontFragment);

                //Console.WriteLine("Buffer size: {0}", reply.Buffer.Length);

                ms = reply.RoundtripTime;

            } else {

                ms = -1;

            }

        }

    }