SPF Record Flattener

New-FlattenSPFRecord.ps1

[CmdletBinding()]
param
(
    [string]$DNSServer = "8.8.8.8",

    [string]$DomainName = "domain.com",

    [parameter(Mandatory=$true)]
    [AllowNull()]
    [AllowEmptyString()]
    [AllowEmptyCollection()]
    [string[]]$DomainsToFlatten,

    [parameter(Mandatory=$true)]
    [AllowNull()]
    [AllowEmptyString()]
    [AllowEmptyCollection()]
    [string[]]$IPv4Addresses,

    [parameter(Mandatory=$true)]
    [AllowNull()]
    [AllowEmptyString()]
    [AllowEmptyCollection()]
    [string[]]$IPv6Addresses,

    [parameter(Mandatory=$true)]
    [AllowNull()]
    [AllowEmptyString()]
    [AllowEmptyCollection()]
    [string[]]$Includes
)

function Get-DomainSPFRecordIPAddresses {
    [CmdletBinding()]
    param
    (
        [string]$DomainName,
        [string]$DNSServer
    )

    $ip_list = New-Object System.Collections.ArrayList

    $domain_spf_record = Resolve-DnsName $DomainName -Type TXT -Server $DNSServer | Where-Object {$_.Strings -match "spf"} | Select-Object -ExpandProperty Strings

    foreach ($entry in ($domain_spf_record -split " ")){
        if ($entry -match "ip4|ip6")
        {
            $ip_list.Add($entry.replace("ip4:","").replace("ip6:","").trim()) | Out-Null
        }

        if ($entry -match "include")
        {
            $sub_lookup_domain_name = $entry.replace("include:","").trim()
            $sub_list = Get-DomainSPFRecordIPAddresses -DomainName $sub_lookup_domain_name -DNSServer $DNSServer
            $sub_list | ForEach-Object {
                $ip_list.Add($_) | Out-Null
            }
        }
    }

    Return $ip_list | Select-Object -Unique
}

$spf_entries_list = New-Object System.Collections.ArrayList

0..4 | ForEach-Object {
    $spf_record_init = New-Object System.Collections.ArrayList
    $spf_record_init.Add("v=spf1 ") | Out-Null

    if ($_ -eq 0)
    {
        $spf_record_init.Add("mx ") | Out-Null

        if ($Includes)
        {
            foreach ($include in $Includes)
            {
                $spf_record_init.Add("include:$include ") | Out-Null
            }
        }

        $spf_record_init.Add("include:netblocks1.$DomainName ") | Out-Null
        $spf_record_init.Add("include:netblocks2.$DomainName ") | Out-Null
        $spf_record_init.Add("include:netblocks3.$DomainName ") | Out-Null
        $spf_record_init.Add("include:netblocks4.$DomainName ") | Out-Null
        $spf_record_init.Add("-all") | Out-Null
    }

    $spf_entries_list.Add($spf_record_init) | Out-Null
}

$ip_list = New-Object System.Collections.ArrayList
$spf_record_builder = New-Object System.Collections.ArrayList

if ($DomainsToFlatten)
{
    foreach ($domain_name in $DomainsToFlatten)
    {
        Get-DomainSPFRecordIPAddresses -DomainName $domain_name -DNSServer $DNSServer | ForEach-Object {
            $ip_list.Add($_) | Out-Null
        }
    }

    foreach ($ip in $ip_list)
    {
        if ($ip -match ":")
        {
            $spf_record_builder.Add("ip6:$ip ") | Out-Null
        }
        elseif ($ip -match ".")
        {
            $spf_record_builder.Add("ip4:$ip ") | Out-Null
        }
    }
}

if ($IPv4Addresses){
    foreach ($ipv4 in $IPv4Addresses)
    {
        $spf_record_builder.Add("ip4:$ipv4 ") | Out-Null
    }
}

if ($IPv6Addresses)
{
    foreach ($ipv6 in $IPv6Addresses)
    {
        $spf_record_builder.Add("ip4:$ipv6 ") | Out-Null
    }
}

$spf_record_builder = $spf_record_builder | Sort-Object

$counter = 1

foreach ($ip in $spf_record_builder)
{
    $spf_length = [System.Text.Encoding]::ASCII.GetByteCount($spf_entries_list[$counter] -join "`n") + [System.Text.Encoding]::ASCII.GetByteCount($ip) + [System.Text.Encoding]::ASCII.GetByteCount("-all")

    if ($spf_length -lt 476)
    {
        $spf_entries_list[$counter].Add($ip) | Out-Null
    }
    elseif ($spf_length -gt 476)
    {
        $spf_entries_list[$counter].Add("-all") | Out-Null
        $counter++
    }

    $index = [array]::IndexOf($spf_record_builder, $ip)

    if ($index -eq ($spf_record_builder.Count - 1))
    {
        $spf_entries_list[$counter].Add("-all") | Out-Null
    }
}

$spf_entries_strings_list = New-Object System.Collections.ArrayList

foreach ($entry in $spf_entries_list)
{
    $entry_length = ($entry -join "").Length
    $entry_index = [array]::IndexOf($spf_entries_list, $entry)

    $custom_object = [PSCustomObject]@{
        DNSRecordName = $null
        DNSRecordZoneName = $null
        DNSEntryValue = $null
    }

    if ($entry_index -eq 0)
    {
        $custom_object.DNSRecordName = "@"
    }
    else
    {
        $custom_object.DNSRecordName = "netblocks$entry_index"
    }

    $custom_object.DNSRecordZoneName = $DomainName

    if ($entry[$entry.Count - 1] -notmatch "-all")
    {
        $entry.Add("-all") | Out-Null
    }

    $entry.Add("") | Out-Null

    $custom_object.DNSEntryValue = $entry #-join "`n"

    $spf_entries_strings_list.Add($custom_object) | Out-Null
}

return $spf_entries_strings_list