/******************************************************************************************************************
* Class: Trace
* Description: Traces path of an ip packet with its respond time
* Author: Sanjay Ahuja
* Date: 5/15/2002
* Copyright? ?2002, Sanjay Ahuja (lparam@hotmail.com). Use it as you want till you leave my name intact
/******************************************************************************************************************/
using System;
using System.Net;
using System.Net.Sockets;
//ICMP constants
struct ICMPConstants
{
public const int ICMP_ECHOREPLY= 0; // Echo reply query
public const int ICMP_TIMEEXCEEDED= 11; // TTL exceeded error
public const int ICMP_ECHOREQ= 8; // Echo request query
public const int MAX_TTL= 256; // Max TTL
}
//ICMP header, size is 8 bytes
struct ICMP
{
public byte type; // Type
public byte code; // Code
public ushort checksum; // Checksum
public ushort id; // Identification
public ushort seq; // Sequence
}
// ICMP Echo Request, size is 12+ 32 (PACKET_SIZE as defined in class Trace)= 44 bytes
struct REQUEST
{
public ICMP m_icmp;
public byte []m_data;
}
class Trace
{
const int PACKET_SIZE= 32;
public static void Main(string[] args)
{
try
{
//verify command line
if(args.Length== 0)
{
Console.WriteLine("usage: trace
return;
}
//Create Raw ICMP Socket
Socket s= new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);
//destination
IPEndPoint ipdest= new IPEndPoint(Dns.Resolve(args[0]).AddressList[0],80);
//Source
IPEndPoint ipsrc= new IPEndPoint(Dns.GetHostByName(Dns.GetHostName()).AddressList[0],80);
EndPoint epsrc= (EndPoint)ipsrc;
ICMP ip= new ICMP();
ip.type = ICMPConstants.ICMP_ECHOREQ;
ip.code = 0;
ip.checksum = 0;
ip.id = (ushort)DateTime.Now.Millisecond; //any number you feel is kinda unique :)
ip.seq = 0;
REQUEST req= new REQUEST();
req.m_icmp= ip;
req.m_data = new Byte[PACKET_SIZE];
//Initialize data
for (int i = 0; i < req.m_data.Length; i++)
{
req.m_data[i] = (byte)'S';
}
//this function would gets byte array from the REQUEST structure
Byte[] ByteSend= CreatePacket(req);
//send requests with increasing number of TTL
for(int ittl=1; ittl<= ICMPConstants.MAX_TTL; ittl++)
{
Byte[] ByteRecv = new Byte[256];
//Socket options to set TTL and Timeouts
s.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.IpTimeToLive, ittl);
s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout,10000);
s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout,10000);
//Get current time
DateTime dt= DateTime.Now;
//Send Request
int iRet= s.SendTo(ByteSend, ByteSend.Length, SocketFlags.None, ipdest);
//check for Win32 SOCKET_ERROR
if(iRet== -1)
Console.WriteLine("error sending data");
//Receive
iRet= s.ReceiveFrom(ByteRecv, ByteRecv.Length, SocketFlags.None, ref epsrc);
//Calculate time required
TimeSpan ts= DateTime.Now- dt;;
//check if response is OK
if(iRet== -1)
Console.WriteLine("error getting data");
Console.WriteLine("TTL= {0,-5} IP= {1,-20} Time= {2,3}ms",ittl,((IPEndPoint)epsrc).Address,ts.Milliseconds);
//reply size should be sizeof REQUEST + 20 (i.e sizeof IP header),it should be an echo reply
//and id should be same
if((iRet == PACKET_SIZE+ 8 +20)&& (BitConverter.ToInt16(ByteRecv,24) == BitConverter.ToInt16(ByteSend,4))&& (ByteRecv[20] == ICMPConstants.ICMP_ECHOREPLY))
break;
//time out
if(ByteRecv[20] != ICMPConstants.ICMP_TIMEEXCEEDED)
{
Console.WriteLine("unexpected reply, quitting...");
break;
}
}
}
catch(SocketException e)
{
Console.WriteLine(e.Message);
}
catch(Exception e)
{
Console.WriteLine(e.Message);
}
}
public static byte[] CreatePacket( REQUEST req )
{
Byte[] ByteSend= new Byte[PACKET_SIZE+ 8];
//Create Byte array from REQUEST structure
ByteSend[0]= req.m_icmp.type;
ByteSend[1]= req.m_icmp.code;
Array.Copy(BitConverter.GetBytes(req.m_icmp.checksum), 0, ByteSend, 2, 2);
Array.Copy(BitConverter.GetBytes(req.m_icmp.id), 0, ByteSend, 4, 2);
Array.Copy(BitConverter.GetBytes(req.m_icmp.seq), 0, ByteSend, 6, 2);
for(int i=0; i< req.m_data.Length; i++)
ByteSend[i+8]= req.m_data[i];
//calculate checksum
int iCheckSum = 0;
for (int i= 0; i < ByteSend.Length; i+= 2)
iCheckSum += Convert.ToInt32( BitConverter.ToUInt16(ByteSend,i));
iCheckSum = (iCheckSum >> 16) + (iCheckSum & 0xffff);
iCheckSum += (iCheckSum >> 16);
//update byte array to reflect checksum
Array.Copy(BitConverter.GetBytes((ushort)~iCheckSum), 0, ByteSend, 2, 2);
return ByteSend;
}
}