convert .NET System.Int64 to an IP Address

Question

I have the following System.Net.IPAddress object in Windbg and would like to convert the m_address (4294967295 m_Address) field to the corresponding dotted-quad notation. How can I accomplish this? I see that the m_ToString has a value of 00000000. How is that string obtained?

Name:        System.Net.IPAddress
MethodTable: 71c3d860
EEClass:     71a299f0
Size:        40(0x28) bytes
File:        C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll
Fields:
      MT    Field   Offset                 Type VT     Attr    Value Name
727e821c  40018b1        4         System.Int64  1 instance 4294967295 m_Address
727f2248  40018b2       14        System.String  0 instance 00000000 m_ToString
71c42030  40018b6       1c         System.Int32  1 instance        2 m_Family
727e1994  40018b7       18      System.UInt16[]  0 instance 022c20a8 m_Numbers
727e821c  40018b8        c         System.Int64  1 instance 0 m_ScopeId
727f3aa4  40018b9       20         System.Int32  1 instance        0 m_HashCode
71c3d860  40018ad      7ec System.Net.IPAddress  0   static 022c1ff8 Any
71c3d860  40018ae      7f0 System.Net.IPAddress  0   static 022c203c Loopback
71c3d860  40018af      7f4 System.Net.IPAddress  0   static 022c2080 Broadcast
71c3d860  40018b0      7f8 System.Net.IPAddress  0   static 022c2080 None
71c3d860  40018b3      7fc System.Net.IPAddress  0   static 022c20c4 IPv6Any
71c3d860  40018b4      800 System.Net.IPAddress  0   static 022c2108 IPv6Loopback
71c3d860  40018b5      804 System.Net.IPAddress  0   static 022c214c IPv6None

So it seems at the breakpoint the m_Address field did not have a address. After executing the UdpClient.Receive method. I get the following.

0:000> !DumpObj /d 024a20f8
Name:        System.Net.IPAddress
MethodTable: 71c3d860
EEClass:     71a299f0
Size:        40(0x28) bytes
File:        C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll
Fields:
      MT    Field   Offset                 Type VT     Attr    Value Name
727e821c  40018b1        4         System.Int64  1 instance 100731402 m_Address
727f2248  40018b2       14        System.String  0 instance 024a2198 m_ToString
71c42030  40018b6       1c         System.Int32  1 instance        2 m_Family
727e1994  40018b7       18      System.UInt16[]  0 instance 024a2120 m_Numbers
727e821c  40018b8        c         System.Int64  1 instance 0 m_ScopeId
727f3aa4  40018b9       20         System.Int32  1 instance        0 m_HashCode
71c3d860  40018ad      7ec System.Net.IPAddress  0   static 022c1ff8 Any
71c3d860  40018ae      7f0 System.Net.IPAddress  0   static 022c203c Loopback
71c3d860  40018af      7f4 System.Net.IPAddress  0   static 022c2080 Broadcast
71c3d860  40018b0      7f8 System.Net.IPAddress  0   static 022c2080 None
71c3d860  40018b3      7fc System.Net.IPAddress  0   static 022c20c4 IPv6Any
71c3d860  40018b4      800 System.Net.IPAddress  0   static 022c2108 IPv6Loopback
71c3d860  40018b5      804 System.Net.IPAddress  0   static 022c214c IPv6None
0:000> !DumpObj /d 024a2198
Name:        System.String
MethodTable: 727f2248
EEClass:     72423444
Size:        32(0x20) bytes
File:        C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll
String:      10.10.1.6
Fields:
      MT    Field   Offset                 Type VT     Attr    Value Name
727f3aa4  40000aa        4         System.Int32  1 instance        9 m_stringLength
727f2c40  40000ab        8          System.Char  1 instance       31 m_firstChar
727f2248  40000ac        c        System.String  0   shared   static Empty

But the question remains what is the mathematical formula to convert the Int64 to an IP Address?

Answer 1

An IP Address is 4 8 bit octets.

For example, the value 0x2414188f in big-endian format would be the IP address "143.24.20.36".

605296783 == 0x2414188f

0x2414188f == 100100000101000001100010001111

00100100 . 00010100 . 00011000 . 10001111

Because this is Big Endian you need to reverse the order of the bytes so

00100100 == 36

00010100 == 20

00011000 == 24

10001111 == 143

So in other words - take the Int64 value (also called a long). Convert it to a binary representation (byte[]). Read the first byte in and convert it to an int. This will be the 4th(last) octet of the ip address. Read the second byte convert to int, this is the 3rd octet of the ip. Read the third byte this is the 2nd octet. Read the last byte this is the 1st octet.

I dont have my IDE right now but this should do the trick

var bytes = BitConverter.GetBytes(value);
var fourthOctet = BitConverter.ToInt32(bytes,0);
var thirdOctet = BitConverter.ToInt32(bytes,1);
var secondOctet = BitConverter.ToInt32(bytes,2);
var firstOctet = BitConverter.ToInt32(bytes,3);

Answer 2

using System;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;

namespace SOFAcrobatics
{
    public static class Launcher
    {
        public static void Main ()
        {
            Console.WriteLine(Launcher.IPv4ToQuadNotation(new IPAddress(4294967295)));
            // outputs 255.255.255.255
            Console.ReadKey(true);
        }

        public static String IPv4ToQuadNotation (IPAddress ip)
        {
            String output = String.Empty;
            foreach (Match m in Regex.Matches(ip.Address.ToString("X8"), @"[A-F0-9]{2}"))
            {
                output += (Int32.Parse(m.Value, NumberStyles.HexNumber) + ".");
            }
            return output.Substring(0, (output.Length - 1));
        }
    }
}