//----------------------------------------+----------------------------------------
// Ping.cs - Ping utility written in C# and .Net similar to the classic Ping.exe
//
//     Copyright© 2002, 2003, Christopher G. Lewis - HTTP://www.ChristopherLewis.com
//
//  Supports
//    -t             Ping the specified host until stopped.
//    -a             Resolve addresses to hostnames.
//    -n count       Number of echo requests to send.
//    -l size        Send buffer size.
//    -w timeout     Timeout in milliseconds to wait for each reply.
//
//  Added code to reports ping stats.
//
//
// You might think that this is derived from Ping example by 
//   Saurabh Nandu (saurabhn@webveda.com)http://learncsharp.cjb.net  
//
//  But actually, Lance Olson of MSDN Magazine did it first
//    http://msdn.microsoft.com/msdnmag/issues/01/02/netpeers/netpeers.asp
//  and Peter A. Bromberg, Ph.D. ( pbromberg@yahoo.com) made it a web service
//    acording to http://www.eggheadcafe.com/articles/20020209.asp
//
//----------------------------------------+----------------------------------------

using System;
using System.Net;
using System.Net.Sockets;

namespace Ping
{
  /// <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[] args)
    {
      string strHostToPing = "";
      bool   bLoop = false;
      bool   bAddressResolve = false;
      int    iBytes = 32;
      uint   lngCount = 4;
      uint   lngTimeout = 1000;

      if(args.Length == 0)
      {
        //If user did not enter any Parameter inform him
        Console.WriteLine("Usage: Ping [-t] [-a] [-l size] [-n count] [-w timeout] <hostname> ") ;
        Console.WriteLine("<hostname> The name of the Host who you want to ping");
        Console.WriteLine("Options:");
        Console.WriteLine("    -t             Ping the specified host until stopped.") ;
        Console.WriteLine("    -a             Resolve addresses to hostnames.") ;
        Console.WriteLine("    -n count       Number of echo requests to send.") ;
        Console.WriteLine("    -l size        Send buffer size.") ;
        Console.WriteLine("    -w timeout     Timeout in milliseconds to wait for each reply.");
        return;
      }

      for (int iCount=0; iCount < args.Length; iCount++) 
      {
        string temp = args[iCount];
        switch (temp.ToLower()) 
        {
          case "-t":
            bLoop = true;
            break;

          case "-a":
            bAddressResolve = true;
            break;

          case "-l":
            iCount++;
            try 
            {
              //Next arg s/b an int
              iBytes = Int32.Parse(args[iCount]);
              if (iBytes < 0 | iBytes > 65500)
              {
                Console.WriteLine("Bad value for option -l, valid range is from 0 to 65500.");
                return;
              }
            }
            catch 
            {
              Console.WriteLine("Bad value for option -l, valid range is from 0 to 65500.");
              return;
            }
            break;

          case "-n":
            iCount++;
            try 
            {
              //Next arg s/b an int
              lngCount = UInt32.Parse(args[iCount]);
              if (lngCount  < 0 | lngCount  > UInt32.MaxValue)
              {
                Console.WriteLine("Bad value for option -n, valid range is from 0 to {0}.",UInt32.MaxValue);
                return;
              }
            }
            catch 
            {
              Console.WriteLine("Bad value for option -n, valid range is from 0 to {0}.",UInt32.MaxValue);
              return;
            }
            break;
            
          case "-w":
            iCount++;
            try 
            {
              //Next arg s/b an int
              lngTimeout = UInt32.Parse(args[iCount]);
              if (lngTimeout  < 1 | lngTimeout  > UInt32.MaxValue)
              {
                Console.WriteLine("Bad value for option -w, valid range is from 1 to {0}.",UInt32.MaxValue);
                return;
              }
            }
            catch 
            {
              Console.WriteLine("Bad value for option -w, valid range is from 1 to {0}.",UInt32.MaxValue);
              return;
            }
            break;
          default:
            strHostToPing = temp;
            break;
        }
      }

      //Check for continuous
      if (bLoop) lngCount = 0;

      //Do the ping
      PingHost(strHostToPing, iBytes, lngCount, lngTimeout );
    }

    /// <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 strPingHost, int iPingBytes, uint lngPingCount, uint lngPingTimeout)
    {
      const int     MAX_PACKET_SIZE = 65535;
      //Declare the IPHostEntry 
      IPHostEntry   PingTarget, PingSource;
      int           iBytesReceived = 0;
      int           dwStart = 0, dwStop = 0;
      uint          iLoop = 0;
      bool          bContinuous = false;
      //Random ICMP identification.
      // This fixes the bug where this ICMP would listen to all ICMP transmits
      Random        rndIdent = new Random();
      ushort        iIdent = (ushort) rndIdent.Next(ushort.MaxValue);

      // Get the server endpoint
      try
      {
        PingTarget = Dns.GetHostByName(strPingHost);
      }
      catch(Exception)
      {
        Console.WriteLine("Unkown host {0}" , strPingHost); // fail
        return;
      }

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

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

      Console.WriteLine("\nPinging {0} [{1}] with {2} bytes of data:\n", strPingHost, 
        ipepServer.Address.ToString(), iPingBytes);

      //check for continuous
      if (lngPingCount == 0) bContinuous = true;

      //Loop the ping
      long lngPacketsSent = 0, lngPacketsReceived = 0, lngTotalTransmitTime = 0;
      int  iMinTransmitTime = int.MaxValue, iMaxTransmitTime = int.MinValue;
      ushort iSeq = 0;
      do 
      {
        bool bReceived = false ;

        //Initialize a Socket of the Type ICMP
        Socket PingSocket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);
        //Set socket timeout, but this doesn't seem to work...
        PingSocket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, (int) lngPingTimeout);
        PingSocket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, (int) lngPingTimeout);
        
        // Initialize the buffers. The receive buffer is the size of the
        // ICMP header plus the IP header (20 bytes)
        byte [] ReceiveBuffer = new byte [MAX_PACKET_SIZE];

        dwStart = System.Environment.TickCount; // Start timing
        //Gather stats
        lngPacketsSent ++;


        //Create the next packet in our sequence
        IcmpPacket PingPacket = new IcmpPacket();
        if (!GetICMPPacket(PingPacket, iIdent, iSeq++, iPingBytes) )
        {
          Console.WriteLine("Error in Making Packet");
          return;
        }
        int iPacketSize = iPingBytes + 8;
        // Move this ICMPPacket into a byte buffer
        byte [] byteSendBuffer = new byte[ iPacketSize ];
        //serialize this PingPacket into a byte array
        int iResult = 0;
        iResult = Serialize(PingPacket, byteSendBuffer, iPacketSize, iPingBytes );
        if( iResult == -1 )//if there is a error report it
        {
          Console.WriteLine("Error in Making Packet");
          return;
        }

        //send the Packet over the socket
        iResult = PingSocket.SendTo(byteSendBuffer, iPacketSize, SocketFlags.None , epServer);
        if ((iResult) == SOCKET_ERROR)
        {
          Console.WriteLine("Socket Error cannot Send Packet");
        }
        //Receive the bytes
        iBytesReceived = 0;
        //loop while waiting checking the time of the server responding 
        while(!bReceived)
        {
          try 
          {
            iBytesReceived = PingSocket.ReceiveFrom(ReceiveBuffer, MAX_PACKET_SIZE, SocketFlags.None, ref EndPointFrom);
          }
          catch //(Exception e)
          {
            //Console.WriteLine ("Request timed out. \n{0}", e.Message);
            Console.WriteLine ("Request timed out.");
            bReceived = false;
            break;
          }
          //OK, check the ident & seq
          int iTemp = ReceiveBuffer[25] * 256 + ReceiveBuffer[24];
          ushort iRecIdent = (ushort) iTemp;
          iTemp = ReceiveBuffer[27] * 256 + ReceiveBuffer[26];
          ushort iRecSeq   = (ushort) iTemp;
          if ( (iRecIdent != iIdent) || (iRecSeq != (iSeq-1)) )   //Not our packet
          {   
            Console.WriteLine ("Request timed out.");
            bReceived = false;
            break;
          }


          if (iBytesReceived == SOCKET_ERROR)
          {
            Console.WriteLine("Host not Responding") ;
            bReceived = false;
            break;
          } 
          else if (iBytesReceived > 0) 
          {

            bReceived = true;
            dwStop = System.Environment.TickCount - dwStart; // stop timing

            //Check for timeout
            if ( dwStop > lngPingTimeout)
            {
              Console.WriteLine ("Request timed out.");
              bReceived = false;
              System.Threading.Thread.Sleep(System.TimeSpan.FromMilliseconds(1000));
              break;
            }
            if (dwStop < 10) 
            {
              Console.WriteLine("Reply from {0}: bytes: {1} time:<10ms ({2})", ipepServer.Address.ToString(), iBytesReceived - 28, iRecSeq);
            } 
            else 
            {
              Console.WriteLine("Reply from {0}: bytes: {1} time: {2}ms ({3})", ipepServer.Address.ToString(), iBytesReceived - 28, dwStop, iRecSeq);
            }
            break;
          } 
        }//while

        //Gather stats
        if (bReceived) 
        {
          lngPacketsReceived++;
          lngTotalTransmitTime += dwStop;
          if (dwStop > iMaxTransmitTime) iMaxTransmitTime = dwStop;
          if (dwStop < iMinTransmitTime) iMinTransmitTime = dwStop;
        }
        iLoop++;

        if (bReceived & 
          (bContinuous | (iLoop < lngPingCount)))           //not last ping
        { 
          System.Threading.Thread.Sleep(System.TimeSpan.FromMilliseconds(1000));
        }
        //close the socket
        PingSocket.Shutdown(SocketShutdown.Both);
        PingSocket.Close();
      } while (bContinuous | (iLoop < lngPingCount));  //Do

 
      //Report stats
      Console.WriteLine("\nPing statistics for {0}", ipepServer.Address.ToString());
      if (lngPacketsSent == 0) 
      {
        Console.WriteLine("    Packets: Sent = {0}, Received = {1}, Lost = {2} ({3}% loss),", lngPacketsSent, lngPacketsReceived, lngPacketsSent-lngPacketsReceived, 0 );
      } 
      else
      {
        Console.WriteLine("    Packets: Sent = {0}, Received = {1}, Lost = {2} ({3}% loss),", lngPacketsSent, lngPacketsReceived, lngPacketsSent-lngPacketsReceived, ((double) (lngPacketsSent-lngPacketsReceived)/lngPacketsSent)* 100 );
      }
      Console.WriteLine("Approximate round trip times in milli-seconds:");
      if (lngPacketsReceived == 0) 
      {
        Console.WriteLine("    Minimum = {0}ms, Maximum =  {1}ms, Average =  {2}ms", 0, 0, 0 );
      } 
      else
      {
        Console.WriteLine("    Minimum = {0}ms, Maximum =  {1}ms, Average =  {2}ms", iMinTransmitTime, iMaxTransmitTime,(int) ((double) (lngTotalTransmitTime/lngPacketsReceived)) );
      }
      return;
    }

    
    /// <summary>
    ///  This method creates an ICMP Packet
    /// </summary>
    public static bool GetICMPPacket(IcmpPacket PingPacket, ushort Identifier, ushort SequenceNumber, int PingBytes)
    {
      int iPacketSize = 0;

      // Construct the packet to send
      PingPacket.Type = ICMP_ECHO; //8
      PingPacket.SubCode = 0; 
      PingPacket.CheckSum = UInt16.Parse("0");
      PingPacket.Identifier   = Identifier;
      PingPacket.SequenceNumber  = SequenceNumber;
      PingPacket.Data = new Byte[PingBytes];
      //Initialize the Packet.Data
      for (int iCount = 0; iCount < PingBytes; iCount++)
      {
        PingPacket.Data[iCount] = (byte)'#';
      }

      //Variable to hold the total Packet size
      iPacketSize = PingBytes + 8;
      byte [] bytPktBuffer = new byte[iPacketSize];
      int iResult = 0;

      //Call a Method Serialize which counts the total number of Bytes in the Packet
      iResult = Serialize(PingPacket, bytPktBuffer, iPacketSize, PingBytes );
      if( iResult == -1 )//Error in Packet Size
      {
        Console.WriteLine("Error in Making Packet");
        return false;
      }

      // now get this critter into a ushort array 
      ushort [] cksum_buffer = new ushort[Convert.ToInt32( Math.Ceiling( Convert.ToDouble(iResult) / 2))];
      
      //Code to initialize the ushort array 
      int icmp_header_buffer_index = 0;
      for( int iCount = 0; iCount < cksum_buffer.Length; iCount++ ) 
      {
        cksum_buffer[iCount] = BitConverter.ToUInt16(bytPktBuffer, icmp_header_buffer_index);
        icmp_header_buffer_index += 2;
      }
      //Call a method which will return a checksum and save the checksum to the Packet
      PingPacket.CheckSum = CheckSum(cksum_buffer);

      return true;
    }
    
    /// <summary>
    ///  This method is used to get the Packet and calculates the total size
    ///  of the Pack by converting it to byte array
    /// </summary>
    public static int Serialize(IcmpPacket ThisPacket, byte[] Buffer, int PacketSize, int PingData )
    {
      int cbReturn = 0;
      // serialize the struct into the array
      int iIndex = 0;

      byte [] b_type = new byte[1];
      b_type[0] = ThisPacket.Type;

      byte [] b_code = new byte[1];
      b_code[0] = ThisPacket.SubCode;

      byte [] b_cksum = BitConverter.GetBytes(ThisPacket.CheckSum);
      byte [] b_id    = BitConverter.GetBytes(ThisPacket.Identifier);
      byte [] b_seq   = BitConverter.GetBytes(ThisPacket.SequenceNumber);

      // Console.WriteLine("Serialize type ");
      Array.Copy( b_type, 0, Buffer, iIndex, b_type.Length );
      iIndex += b_type.Length;

      // Console.WriteLine("Serialize code ");
      Array.Copy( b_code, 0, Buffer, iIndex, b_code.Length );
      iIndex += b_code.Length;

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

      // Console.WriteLine("Serialize id ");
      Array.Copy( b_id, 0, Buffer, iIndex, b_id.Length );
      iIndex += b_id.Length;

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

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

      cbReturn = iIndex;
      return cbReturn;
    }
    /// <summary>
    ///   Checksum - 
    ///     Algorithm to create a checksup for a buffer
    /// </summary>
    public static ushort CheckSum( ushort[] BufferToChecksum )
    {
      int iCheckSum = 0;

      for (uint iCount = 0; iCount < BufferToChecksum.Length; iCount++) 
      {
        iCheckSum += Convert.ToInt32( BufferToChecksum[iCount] );
      }

      iCheckSum = (iCheckSum >> 16) + (iCheckSum & 0xffff);
      iCheckSum += (iCheckSum >> 16);
      return (ushort)(~iCheckSum);
    }

    /// <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 ushort   CheckSum;         // ones complement checksum of struct
      public ushort   Identifier;       // identifier
      public ushort   SequenceNumber;   // sequence number  
      public byte[]   Data;             // byte array of data
    } // class IcmpPacket  
  } // class ping
}