Trace Route : Socket Listener : Network C# Source Code

    

/*
C# Network Programming 
by Richard Blum

Publisher: Sybex 
ISBN: 0782141765
*/

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

public class TraceRoute
{
   public static void Main(string[] argv)
   {
      byte[] data = new byte[1024];
      int recv, timestart, timestop;
      Socket host = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);
      IPHostEntry iphe = Dns.Resolve(argv[0]);
      IPEndPoint iep = new IPEndPoint(iphe.AddressList[0], 0);
      EndPoint ep = (EndPoint)iep;
      ICMP packet = new ICMP();

      packet.Type = 0x08;
      packet.Code = 0x00;
      packet.Checksum = 0;
      Buffer.BlockCopy(BitConverter.GetBytes(1), 0, packet.Message, 0, 2);
      Buffer.BlockCopy(BitConverter.GetBytes(1), 0, packet.Message, 2, 2);
      data = Encoding.ASCII.GetBytes("test packet");
      Buffer.BlockCopy(data, 0, packet.Message, 4, data.Length);
      packet.MessageSize = data.Length + 4;
      int packetsize = packet.MessageSize + 4;

      UInt16 chcksum = packet.getChecksum();
      packet.Checksum = chcksum;

      host.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 3000);

      int badcount = 0;
      for (int i = 1; i < 50; i++)
      {
         host.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.IpTimeToLive, i);
         timestart = Environment.TickCount;
         host.SendTo(packet.getBytes(), packetsize, SocketFlags.None, iep);
         try
         {
            data = new byte[1024];
            recv = host.ReceiveFrom(data, ref ep);
            timestop = Environment.TickCount;
            ICMP response = new ICMP(data, recv);
            if (response.Type == 11)
               Console.WriteLine("hop {0}: response from {1}, {2}ms", i, ep.ToString(), timestop-timestart);
            if (response.Type == 0)
            {
               Console.WriteLine("{0} reached in {1} hops, {2}ms.", ep.ToString(), i, timestop-timestart);
               break;
            }
            badcount = 0;
         } catch (SocketException)
         {
            Console.WriteLine("hop {0}: No response from remote host", i);
            badcount++;
            if (badcount == 5)
            {
               Console.WriteLine("Unable to contact remote host");
               break;
            }
         }
      }
      
      host.Close();
   }
}

class ICMP
{
   public byte Type;
   public byte Code;
   public UInt16 Checksum;
   public int MessageSize;
   public byte[] Message = new byte[1024];

   public ICMP()
   {
   }

   public ICMP(byte[] data, int size)
   {
      Type = data[20];
      Code = data[21];
      Checksum = BitConverter.ToUInt16(data, 22);
      MessageSize = size - 24;
      Buffer.BlockCopy(data, 24, Message, 0, MessageSize);
   }

   public byte[] getBytes()
   {
      byte[] data = new byte[MessageSize + 9];
      Buffer.BlockCopy(BitConverter.GetBytes(Type), 0, data, 0, 1);
      Buffer.BlockCopy(BitConverter.GetBytes(Code), 0, data, 1, 1);
      Buffer.BlockCopy(BitConverter.GetBytes(Checksum), 0, data, 2, 2);
      Buffer.BlockCopy(Message, 0, data, 4, MessageSize);
      return data;
   }

   public UInt16 getChecksum()
   {
      UInt32 chcksm = 0;
      byte[] data = getBytes();
      int packetsize = MessageSize + 8;
      int index = 0;

      while ( index < packetsize)
      {
         chcksm += Convert.ToUInt32(BitConverter.ToUInt16(data, index));
         index += 2;
      }
      chcksm = (chcksm >> 16) + (chcksm & 0xffff);
      chcksm += (chcksm >> 16);
      return (UInt16)(~chcksm);
   }
}