C# 实现的Ping功能

 using System;
using System.Drawing;
using System.Collections;
using System.Data;
using System.Net;
using System.Net.Sockets;

///  Ping类
public class Ping
{
    //声明常量
    const int SOCKET_ERROR = -1;
    const int ICMP_ECHO = 8;

    // 程序入口
    public static void Main()
    {
        Ping p = new Ping();
        Console.WriteLine("请输入要 Ping 的IP或者主机名字：");
        string MyUrl = Console.ReadLine();
        Console.WriteLine("正在 Ping " + MyUrl + " ……");
        Console.Write(p.PingHost(MyUrl));
        Console.Read();
    }

    public string PingHost(string host)
    {
        // 声明 IPHostEntry
        IPHostEntry serverHE, fromHE;
        int nBytes = 0;
        int dwStart = 0, dwStop = 0;

        //初始化ICMP的Socket
        Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);
        socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout, 1000);
        // 得到Server EndPoint
        try
        {
            serverHE = Dns.GetHostByName(host);
        }
        catch (Exception)
        {

            return "没有发现主机";
        }

        // 把 Server IP_EndPoint转换成EndPoint
        IPEndPoint ipepServer = new IPEndPoint(serverHE.AddressList[0], 0);
        EndPoint epServer = (ipepServer);

        // 设定客户机的接收Endpoint
        fromHE = Dns.GetHostByName(Dns.GetHostName());
        IPEndPoint ipEndPointFrom = new IPEndPoint(fromHE.AddressList[0], 0);
        EndPoint EndPointFrom = (ipEndPointFrom);

        int PacketSize = 0;
        IcmpPacket packet = new IcmpPacket();

        // 构建要发送的包
        packet.Type = ICMP_ECHO; //8
        packet.SubCode = 0;
        packet.CheckSum = UInt16.Parse("0");
        packet.Identifier = UInt16.Parse("45");
        packet.SequenceNumber = UInt16.Parse("0");
        int PingData = 32; // sizeof(IcmpPacket) - 8;
        packet.Data = new Byte[PingData];

        // 初始化Packet.Data
        for (int i = 0; i < PingData; i++)
        {
            packet.Data[i] = (byte)'#';
        }

        //Variable to hold the total Packet size
        PacketSize = PingData + 8;
        Byte[] icmp_pkt_buffer = new Byte[PacketSize];
        Int32 Index = 0;
        //Call a Method Serialize which counts
        //The total number of Bytes in the Packet
        Index = Serialize(
            packet,
            icmp_pkt_buffer,
            PacketSize,
            PingData);
        //Error in Packet Size
        if (Index == -1)
        {
            return "Error Creating Packet";
        }

        // convert into a UInt16 array

        //Get the Half size of the Packet
        Double double_length = Convert.ToDouble(Index);
        Double dtemp = Math.Ceiling(double_length / 2);
        int cksum_buffer_length = Convert.ToInt32(dtemp);
        //Create a Byte Array
        UInt16[] cksum_buffer = new UInt16[cksum_buffer_length];
        //Code to initialize the Uint16 array
        int icmp_header_buffer_index = 0;
        for (int i = 0; i < cksum_buffer_length; i++)
        {
            cksum_buffer[i] =
                BitConverter.ToUInt16(icmp_pkt_buffer, icmp_header_buffer_index);
            icmp_header_buffer_index += 2;
        }
        //Call a method which will return a checksum
        UInt16 u_cksum = checksum(cksum_buffer, cksum_buffer_length);
        //Save the checksum to the Packet
        packet.CheckSum = u_cksum;

        // Now that we have the checksum, serialize the packet again
        Byte[] sendbuf = new Byte[PacketSize];
        //again check the packet size
        Index = Serialize(
            packet,
            sendbuf,
            PacketSize,
            PingData);
        //if there is a error report it
        if (Index == -1)
        {
            return "Error Creating Packet";

        }

        dwStart = System.Environment.TickCount; // Start timing
        //send the Packet over the socket
        if ((nBytes = socket.SendTo(sendbuf, PacketSize, 0, epServer)) == SOCKET_ERROR)
        {
            return "Socket Error: cannot send Packet";
        }
        // Initialize the buffers. The receive buffer is the size of the
        // ICMP header plus the IP header (20 bytes)
        Byte[] ReceiveBuffer = new Byte[256];
        nBytes = 0;
        //Receive the bytes
        bool recd = false;
        int timeout = 0;

        //loop for checking the time of the server responding
        while (!recd)
        {
            nBytes = socket.ReceiveFrom(ReceiveBuffer, 256, 0, ref EndPointFrom);
            if (nBytes == SOCKET_ERROR)
            {
                return "主机没有响应";

            }
            else if (nBytes > 0)
            {
                dwStop = System.Environment.TickCount - dwStart; // stop timing
                return "Reply from " + epServer.ToString() + " in " + dwStop + "ms.  Received: " + nBytes + " Bytes.";

            }
            timeout = System.Environment.TickCount - dwStart;
            if (timeout > 1000)
            {
                return "超时";
            }
        }

        //close the socket
        socket.Close();
        return "";
    }
    /// <summary>
    ///  This method get the Packet and calculates the total size
    ///  of the Pack by converting it to byte array
    /// </summary>
    public static Int32 Serialize(IcmpPacket packet, Byte[] Buffer,
        Int32 PacketSize, Int32 PingData)
    {
        Int32 cbReturn = 0;
        // serialize the struct into the array
        int Index = 0;

        Byte[] b_type = new Byte[1];
        b_type[0] = (packet.Type);

        Byte[] b_code = new Byte[1];
        b_code[0] = (packet.SubCode);

        Byte[] b_cksum = BitConverter.GetBytes(packet.CheckSum);
        Byte[] b_id = BitConverter.GetBytes(packet.Identifier);
        Byte[] b_seq = BitConverter.GetBytes(packet.SequenceNumber);

        Array.Copy(b_type, 0, Buffer, Index, b_type.Length);
        Index += b_type.Length;

        Array.Copy(b_code, 0, Buffer, Index, b_code.Length);
        Index += b_code.Length;

        Array.Copy(b_cksum, 0, Buffer, Index, b_cksum.Length);
        Index += b_cksum.Length;

        Array.Copy(b_id, 0, Buffer, Index, b_id.Length);
        Index += b_id.Length;

        Array.Copy(b_seq, 0, Buffer, Index, b_seq.Length);
        Index += b_seq.Length;

        // copy the data
        Array.Copy(packet.Data, 0, Buffer, Index, PingData);
        Index += PingData;
        if (Index != PacketSize/* sizeof(IcmpPacket)  */)
        {
            cbReturn = -1;
            return cbReturn;
        }

        cbReturn = Index;
        return cbReturn;
    }
    /// <summary>
    ///  This Method has the algorithm to make a checksum
    /// </summary>
    public static UInt16 checksum(UInt16[] buffer, int size)
    {
        Int32 cksum = 0;
        int counter;
        counter = 0;

        while (size > 0)
        {
            UInt16 val = buffer[counter];

            cksum += Convert.ToInt32(buffer[counter]);
            counter += 1;
            size -= 1;
        }

        cksum = (cksum >> 16) + (cksum & 0xffff);
        cksum += (cksum >> 16);
        return (UInt16)(~cksum);
    }
}
/// 类结束
/// <summary>
///  Class that holds the Pack information
/// </summary>
public class IcmpPacket
{
    public Byte Type;    // type of message
    public Byte SubCode;    // type of sub code
    public UInt16 CheckSum;   // ones complement checksum of struct
    public UInt16 Identifier;      // identifier
    public UInt16 SequenceNumber;     // sequence number
    public Byte[] Data;

} // class IcmpPacket