国外站点上转过来的资料，模拟ping程序

namespace SaurabhPing
{
  using System;
  using System.Net;
  using System.Net.Sockets;
  /// <summary>
  ///        The Main Ping Class
  /// </summary>
  class Ping
  {
    //Declare some Constant Variables
    const int SOCKET_ERROR = -1;        
    const int ICMP_ECHO = 8;
    /// <summary>
    ///        The Starting Point of the Class
    ///        It Takes the Hostname parameter
    /// </summary>
    public static void Main(string[] argv)
    {
      if(argv.Length==0)
      {
    //If user did not enter any Parameter inform him
    Console.WriteLine("Usage:Ping <hostname> /r") ;
    Console.WriteLine("<hostname> The name of the Host who you want to ping");
    Console.WriteLine("/r Ping the host continuously") ;
      }
      else if(argv.Length==1)
      {
    //Just the hostname provided by the user
    //call the method "PingHost" and pass the HostName as a parameter
    PingHost(argv[0]) ;
      }
      else if(argv.Length==2)
      {
    //the user provided the hostname and the switch
    if(argv[1]=="/r")
    {
      //loop the ping program
      while(true)
      {
        //call the method "PingHost" and pass the HostName as a parameter
        PingHost(argv[0]) ;
      }
        }
    else
    {
      //if the user provided some other switch
      PingHost(argv[0]) ;
     }
       }
       else
       {
     //Some error occurred
     Console.WriteLine("Error in Arguments") ;
        }
     }
        
      /// <summary>
      ///        This method takes the "hostname" of the server
      ///        and then it ping''s it and shows the response time
      /// </summary>
      public static void PingHost(string host)
      {
    //Declare the IPHostEntry
    IPHostEntry serverHE, fromHE;
    int nBytes = 0;
    int dwStart = 0, dwStop = 0;
    //Initilize a Socket of the Type ICMP
    Socket socket =
    new Socket(AddressFamily.AfINet, SocketType.SockRaw, ProtocolType.ProtICMP);
    
    // Get the server endpoint
    try
    {
      serverHE = DNS.GetHostByName(host);    
    }
    catch(Exception)
    {
      Console.WriteLine("Host not found"); // fail
      return ;
    }

    // Convert the server IP_EndPoint to an EndPoint
    IPEndPoint ipepServer = new IPEndPoint(serverHE.AddressList[0], 0);
    EndPoint epServer = (ipepServer);    

    // Set the receiving endpoint to the client machine
    fromHE = DNS.GetHostByName(DNS.GetHostName());
    IPEndPoint ipEndPointFrom = new IPEndPoint(fromHE.AddressList[0], 0);        
    EndPoint EndPointFrom = (ipEndPointFrom);

    int PacketSize = 0;
    IcmpPacket packet = new IcmpPacket();
    // Construct the packet to send
    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];
    //Initilize the 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 )
    {
      Console.WriteLine("Error in Making Packet");
      return ;
    }
          
    // now get this critter into a UInt16 array
             
    //Get the Half size of the Packet
    Double double_length = Convert.ToDouble(Index);
    Double dtemp = Math.Ceil( 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 )
    {
      Console.WriteLine("Error in Making Packet");
      return ;
    }
                    

    dwStart = System.Environment.TickCount; // Start timing
    //send the Pack over the socket
    if ((nBytes = socket.SendTo(sendbuf, PacketSize, 0, epServer)) == SOCKET_ERROR)
    {        
      Console.WriteLine("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)
      {
        Console.WriteLine("Host not Responding") ;
        recd=true ;
        break;
      }
      else if(nBytes>0)
      {
        dwStop = System.Environment.TickCount - dwStart; // stop timing
        Console.WriteLine("Reply from "+epServer.ToString()+" in "
        +dwStop+"MS :Bytes Received"+nBytes);
        recd=true;
        break;
      }
      timeout=System.Environment.TickCount - dwStart;
      if(timeout>1000)
      {
        Console.WriteLine("Time Out") ;
        recd=true;
      }
        }
                
    //close the socket
    socket.Close();     
      }
      /// <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);
            
    // Console.WriteLine("Serialize type ");
    Array.Copy( b_type, 0, Buffer, Index, b_type.Length );
    Index += b_type.Length;
            
    // Console.WriteLine("Serialize code ");
    Array.Copy( b_code, 0, Buffer, Index, b_code.Length );
    Index += b_code.Length;

    // Console.WriteLine("Serialize cksum ");
    Array.Copy( b_cksum, 0, Buffer, Index, b_cksum.Length );
    Index += b_cksum.Length;

    // Console.WriteLine("Serialize id ");
    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);
      }
    } // class ping
    /// <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
}