ASP: IPv4 Address Manipulation

Introduction

Author: Martin Warning
Year: 2007
Updated: 2008
License: Free

These are some functions that can be used to convert an IP address from dotted decimal to binary to decimal and from decimal to binary to dotted decimal. This can be useful when you need to compare IP addresses or to save space in storing the IP address in a database.

Code

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ASP
VBScript

Function to convert binary value to decimal:

Function fncBinaryToDecimal(intBinaryValue)
	Do
		fncBinaryToDecimal = fncBinaryToDecimal + (Left(intBinaryValue, 1) * 2 ^ (Len(intBinaryValue) - 1))
		intBinaryValue = Mid(intBinaryValue, 2)
	Loop Until intBinaryValue = ""
End Function

Example: See it in action

Function to convert decimal value to binary

Function fncDecimalToBinary(intDecimalValue)
	Dim intRange : intRange = 4294967296 ' IP's maximum decimal value

	Do While intRange >= 1
		If intDecimalValue >= intRange then
			intDecimalValue = intDecimalValue - intRange
			fncDecimalToBinary = fncDecimalToBinary & "1"
		Else
			fncDecimalToBinary = fncDecimalToBinary & "0"
		End if
		intRange = intRange / 2
	Loop
End Function

Example: See it in action

Function to convert IP to Binary

Function fncIPToBinary(strIP)
	Dim intNewIP : intNewIP = Split(strIP,".")
	Dim i

	For i = 0 To UBound(intNewIP)

		fncIPToBinary = fncIPToBinary & Right(fncDecimalToBinary(cInt(intNewIP(i))),8)
	Next
End Function

To convert the IP address to a decimal value instead of the binary value you just need to send the value generated by the fncIPToBinary function to the fncBinaryToDecimal function.

Example: See it in action

Function to convert binary value to IP

Function fncBinaryToIP(intIP)
	Dim intNewIP(3),i
	intNewIP(0) = Left(intIP,8)
	intNewIP(1) = Right(Left(intIP,16),8)
	intNewIP(2) = Left(Right(intIP,16),8)
	intNewIP(3) = Right(intIP,8)

	For i=0 To 3
		If i > 0 Then
			fncBinaryToIP = fncBinaryToIP & "."
		End If
		fncBinaryToIP = fncBinaryToIP & fncBinaryToDecimal(intNewIP(i))
	Next
End Function

The following validation can be added to make sure that the entered binary value is numeric and also create a binary value of exactly 32 bits if the start value is shorter than 32 bits.

'Validation
If Len(Replace(Replace(intTestValue,1,""),0,"")) > 0 Then
	' Make sure the binary value is a binary value
	intTestValue = ""
ElseIf Len(intTestValue) < 32 AND intTestValue <> "" Then
	' leading 0 when binary value isn't 32 bits
		For j=1 To (32 - Len(intTestValue))
			intTestValue = "0" & intTestValue
		Next
ElseIf Len(intTestValue) > 32 Then
	' select first 32 bits if binary value is longer than 32 bits
	intTestValue = Left(intTestValue,32)
End If

Example: See it in action

Example to convert decimal value to IP

fncBinaryToIP(fncDecimalToBinary(cInt(intTestValue)))

All you need is to use the previous shown fncDecimalToBinary, fncBinaryToIP and fncBinaryToDecimal functions to translate a decimal value to IP. Next is the validation of the decimal input, it has to be numeric and of a value between 0 and 4294967296. The validation goes before you call the translate functions.

'Validation
If NOT isNumeric(intTestValue) Then
	intTestValue = ""
ElseIf intTestValue > 4294967296 OR intTestValue < 0 Then
	intTestValue = ""
End If

Example: See it in action

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ASP: IPv4 Address Manipulation

Introduction

Code

Downloads

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