C#中实现Ping

Code
在C#中实现Ping，代码如下：

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));
}

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)
{
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