Get-SpfLookupCount.ps1
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# Write a function that does an SPF lookup and returns the number og "include" lookups there is # The function should be recursive, so it should be able to follow the includes in the SPF record and count them as well # The function should also be able to handle the limit of 10 lookups, so it should stop if it reaches that limit # The function should return the number of lookups and the SPF record itself # The function should also be able to handle the case where the SPF record is empty or does not exist # The function should also be able to handle the case where the SPF record is not a valid SPF record # The function should also be able to handle the case where the SPF record is not a valid DNS record function Get-SpfLookupCount { param ( [string]$Domain ) # Helper function to perform DNS TXT record lookup function Get-TxtRecord { param ([string]$Domain) try { $records = Resolve-DnsName -Name $Domain -Type TXT -ErrorAction Stop -Server 1.1.1.1 return $records | Where-Object { $_.Strings -match "^v=spf1" } | Select-Object -ExpandProperty Strings } catch { Write-Verbose "Failed to resolve TXT record for domain: $Domain" return $null } } # Recursive function to count SPF includes function Count-Includes { param ( [string]$SpfRecord, [int]$CurrentCount ) if (-not $SpfRecord) { Write-Verbose "SPF record is empty or invalid." return $CurrentCount } $includes = ($SpfRecord -split ' ') | Where-Object { $_ -like "include:*" } foreach ($include in $includes) { $includedDomain = $include -replace "include:", "" Write-Verbose "Processing include for domain: $includedDomain" $includedSpfRecord = Get-TxtRecord -Domain $includedDomain if ($includedSpfRecord) { $CurrentCount = Count-Includes -SpfRecord $includedSpfRecord -CurrentCount ($CurrentCount + 1) -MaxLookups $MaxLookups } else { Write-Verbose "No valid SPF record found for included domain: $includedDomain" } } return $CurrentCount } $spfRecord = Get-TxtRecord -Domain $Domain if (-not $spfRecord) { Write-Output @{ Lookups = 0 SpfRecord = $null Message = "No valid SPF record found for domain: $Domain" } return } $lookupCount = Count-Includes -SpfRecord $spfRecord -CurrentCount 0 -MaxLookups $MaxLookups if ($lookupCount -gt 10) { $spfCountError = "Exceeded SPF lookup limit of 10." } return @{ Lookups = $lookupCount SpfRecord = $spfRecord Message = "SPF lookup completed." Error = $spfCountError } } |