ConvertFrom-CidrToIPvNetwork

readme.md

ConvertFrom-CidrToIPvNetwork -vlsm "10.202.84.0/25"

ConvertFrom-CidrToIPvNetwork -vlsm "2001:489a:a0d::/64"

Test-IpAddressinNetwork -ipaddress -vlsm 10.202.84.0/25

script.ps1

function ConvertFrom-CidrToIPvNetwork
{
    [CmdletBinding()]
    param(
        [Parameter(Mandatory, ValueFromPipeline)]
        [string] $vlsm
    )
    
    $convertToIpAddress = {
        param(
            [int] $byteRange,
            [System.Numerics.BigInteger]$bigInt
        )

        $bytes = $bigInt.ToByteArray()
        $null = [System.Array]::Reverse($bytes, 0, $byteRange)
        $null = [System.Array]::Resize([ref] $bytes, $byteRange)
        [System.Net.IpAddress]::new($bytes)
    }

    $ipAddress, $prefix = $vlsm -split '/'
    $ipAddressIP = [System.Net.IPAddress]::Parse($ipAddress)


    if ($ipAddressIP.AddressFamily -eq 'InterNetwork') {
        # use V4
        $byteRange = 4
    } else {
        # Use V6
        $byteRange = 16
    }

    $ipAddress = [System.Numerics.BigInteger]::new( $ipAddressIP.GetAddressBytes()[($byteRange-1)..0])
    #$ipAddress = [bigint]::new( ([byte[]]$ipAddressIP.GetAddressBytes()[($byteRange-1)..0]), $true, $true )
    $broadcastAddress = ( [System.Numerics.BigInteger]1 -shl ($byteRange* 8) ) - 1
    $subnetMask = $broadcastAddress -shl (($byteRange*8) - $prefix)
    $networkAddress = $ipAddress -band $subnetMask
    $networkBroadcast = $networkAddress -bor (-bnot $subnetMask)
    $startIPAddress = $networkAddress + 1
    $endIPAddress = $networkBroadcast - 1
    $total = [System.Numerics.BigInteger]::Pow(2, (($byteRange*8)- $prefix)) - 2

    [PSCustomObject][Ordered]@{
        IpAddress = $ipAddressIP
        AddressFamily = $ipAddressIP.AddressFamily
        Prefix = $prefix
        Network = & $convertToIpAddress $byteRange $networkAddress
        SubnetMask = & $convertToIpAddress $byteRange $subnetMask
        BroadcastAddress = & $convertToIpAddress $byteRange $broadcastAddress

        Range = [PSCustomObject][Ordered]@{
            Start = & $convertToIpAddress $byteRange $startIPAddress
            End = & $convertToIpAddress $byteRange $endIPAddress
            Total = $total
        }
    }
}

function Test-IpAddressinNetwork {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory, ValueFromPipeline)]
        [string] $ipAddress,
        [Parameter(Mandatory, ValueFromPipeline)]
        [string] $vlsm
    )

    $ipAddressIP = [System.Net.IPAddress]::Parse($ipAddress)
    $vlsmNetwork = ConvertFrom-CidrToIPvNetwork -vlsm $vlsm

    if ($ipAddressIP.AddressFamily -eq 'InterNetwork') {
        # use V4
        $byteRange = 4
    } else {
        # Use V6
        $byteRange = 16
    }

    $ipAddress = [System.Numerics.BigInteger]::new( $ipAddressIP.GetAddressBytes()[($byteRange-1)..0])
    $networkAddress = [System.Numerics.BigInteger]::new( $vlsmNetwork.Network.GetAddressBytes()[($byteRange-1)..0])
    $subnetMask = [System.Numerics.BigInteger]::new( $vlsmNetwork.SubnetMask.GetAddressBytes()[($byteRange-1)..0])

    return ($ipAddress -band $subnetMask) -eq ($networkAddress -band $subnetMask)
}