Main/Set-CustomWinSecureDNS.psm1

function Set-CustomWinSecureDNS {
    [Alias('Set-CDOH')]
    [CmdletBinding()]
    [OutputType([System.String], [Microsoft.Management.Infrastructure.CimInstance])]
    param (
        # checking to make sure the DoH template is valid and not one of the built-in ones
        [ValidatePattern('^https\:\/\/.+\..+\/.*', ErrorMessage = 'The value provided for the parameter DoHTemplate is not a valid DNS over HTTPS template. Please enter a valid DNS over HTTPS template that starts with https, has a TLD and a slash after it. E.g.: https://template.com/')]
        [ValidateScript({ $_ -notmatch 'https://(cloudflare-dns|dns\.google|dns\.quad9)\.com/dns-query' }, ErrorMessage = 'The DoH template you selected is one of the Windows built-in ones. Please select a different DoH template or use the Set-BuiltInWinSecureDNS cmdlet.')]
        [Parameter(Mandatory)][System.String]$DoHTemplate,

        [ValidateCount(1, 2)][System.Net.IPAddress[]]$IPV4s,
        [ValidateCount(1, 2)][System.Net.IPAddress[]]$IPV6s
    )
    begin {
        # Detecting if Verbose switch is used
        [System.Boolean]$Verbose = $PSBoundParameters.Verbose.IsPresent ? $true : $false

        # Importing the $PSDefaultParameterValues to the current session, prior to everything else
        . "$WinSecureDNSMgrModuleRootPath\MainExt\PSDefaultParameterValues.ps1"

        # Importing the required sub-modules
        Import-Module -Force -FullyQualifiedName @(
            "$WinSecureDNSMgrModuleRootPath\Shared\Get-ActiveNetworkAdapterWinSecureDNS.psm1",
            "$WinSecureDNSMgrModuleRootPath\Shared\Get-ManualNetworkAdapterWinSecureDNS.psm1",
            "$WinSecureDNSMgrModuleRootPath\Shared\Select-Option.psm1",
            "$WinSecureDNSMgrModuleRootPath\Shared\Get-IPv6DoHServerIPAddressWinSecureDNSMgr.psm1",
            "$WinSecureDNSMgrModuleRootPath\Shared\Get-IPv4DoHServerIPAddressWinSecureDNSMgr.psm1"
        )

        [System.Boolean]$AutoDetectDoHIPs = $false

        # This service shouldn't be disabled
        # https://github.com/HotCakeX/WinSecureDNSMgr/issues/7
        if (!((Get-Service -Name 'Dnscache').StartType -ne 'Disabled')) {
            throw 'The DNS Client service status is disabled. Please start the service and try again.'
        }

        # If IP addresses were provided manually by user, verify their version
        if ($IPV4s) {
            foreach ($Item in $IPV4s) {
                if ($Item.AddressFamily -ne 'InterNetwork') {
                    throw "The IP address $Item is not a valid IPv4 address."
                }
            }
        }
        if ($IPV6s) {
            foreach ($Item in $IPV6s) {
                if ($Item.AddressFamily -ne 'InterNetworkV6') {
                    throw "The IP address $Item is not a valid IPv6 address."
                }
            }
        }

        # if no IP addresses were provided manually by user, set the $AutoDetectDoHIPs variable to $True
        if (!$IPV4s -and !$IPV6s) {
            $AutoDetectDoHIPs = $True
        }

        # Detect the active network adapter automatically
        [Microsoft.Management.Infrastructure.CimInstance]$ActiveNetworkInterface = Get-ActiveNetworkAdapterWinSecureDNS

        # Display the detected network adapter and ask the user if it's correct
        $ActiveNetworkInterface

        switch (Select-Option -Options 'Yes', 'No - Select Manually', 'Cancel' -Message "`nIs the detected network adapter correct ?") {
            'Yes' {
                $ActiveNetworkInterface = $ActiveNetworkInterface
            }
            'No - Select Manually' {
                # Detect the active network adapter manually
                [Microsoft.Management.Infrastructure.CimInstance]$ActiveNetworkInterface = Get-ManualNetworkAdapterWinSecureDNS
            }
            'Cancel' {
                Write-Host -Object 'Exiting...' -ForegroundColor Yellow
                [System.Boolean]$ShouldExit = $True
                return
            }
        }

        # if user chose to cancel the Get-ManualNetworkAdapterWinSecureDNS function, set the $shouldExit variable to $True and exit the function in the Process block
        if (!$ActiveNetworkInterface) { $ShouldExit = $True; return }

        # Detect the IP address(s) of the DoH domain automatically if not provided by the user
        if ($AutoDetectDoHIPs) {

            # Define the regex for extracting the domain name
            $DomainExtractionRegex = '(?<=https\:\/\/).+?(?=\/)'

            # Test if the input matches the regex
            $DoHTemplate -match $DomainExtractionRegex
            # Access the matched value
            $Domain = $Matches[0]

            Write-Verbose -Message "The extracted domain name is $Domain"

            # Get the IP addresses of the DoH domain
            $IPV4s = Get-IPv4DoHServerIPAddressWinSecureDNSMgr -Domain $Domain
            $IPV6s = Get-IPv6DoHServerIPAddressWinSecureDNSMgr -Domain $Domain

            # If no IP addresses were found for either versions, exit the function
            if (($null -eq $IPV4s) -and ($null -eq $IPV6s)) {

                Throw "No IP addresses were found for the domain $Domain. Please make sure the domain is valid and try again, alternatively you can use the Set-BuiltInWinSecureDNS cmdlet to set one of the built-in DoH templates."

                # Set the flag to indicate the subsequent blocks should be skipped
                [System.Boolean]$ShouldExit = $True
                return
            }
        }
    }
    process {

        # if the user selected Cancel, do not proceed with the process block
        if ($ShouldExit) { Return }

        # check if there is any IP address already associated with "$DoHTemplate" template
        $OldIPs = (Get-DnsClientDohServerAddress | Where-Object { $_.dohTemplate -eq $DoHTemplate }).ServerAddress

        # if there is, remove them
        if ($OldIPs) {
            $OldIPs | ForEach-Object -Process {
                Remove-DnsClientDohServerAddress -ServerAddress $_
            }
        }

        Write-Verbose -Message 'Checking if the IP addresses of the currently selected DoH domain already exist and then deleting them'
        Get-DnsClientDohServerAddress | ForEach-Object -Process {
            if (($_.ServerAddress -in $IPV4s) -or ($_.ServerAddress -in $IPV6s)) {
                Remove-DnsClientDohServerAddress -ServerAddress $_.ServerAddress
            }
        }

        Write-Verbose -Message 'Resetting the network adapter DNS servers back to default to take care of any IPv6 strays'
        Set-DnsClientServerAddress -InterfaceIndex $ActiveNetworkInterface.ifIndex -ResetServerAddresses

        # delete all other previous DoH settings for ALL Interface - Windows behavior in settings when changing DoH settings is to delete all DoH settings for the interface we are modifying
        # but we need to delete all DoH settings for ALL interfaces in here because every time we virtualize a network adapter with external switch of Hyper-V,
        # Hyper-V assigns a new GUID to it, so it's better not to leave any leftover in the registry and clean up after ourselves
        Remove-Item -Path 'Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Dnscache\InterfaceSpecificParameters\*' -Recurse

        if ($null -ne $IPV4s) {

            Write-Verbose -Message 'Adding the new IPv4 addresses to the DoH template in Windows DoH template predefined list'
            $IPV4s | ForEach-Object -Process {

                # defining registry path for DoH settings of the $ActiveNetworkInterface based on its GUID for IPv4
                [System.String]$PathV4 = "Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Dnscache\InterfaceSpecificParameters\$($ActiveNetworkInterface.InterfaceGuid)\DohInterfaceSettings\Doh\$_"

                Write-Verbose -Message 'Associating the new IPv4s with the selected DoH template in Windows DoH template predefined list'
                $null = Add-DnsClientDohServerAddress -ServerAddress $_ -DohTemplate $DoHTemplate -AllowFallbackToUdp $False -AutoUpgrade $True

                # add DoH settings for the specified Network adapter based on its GUID in registry
                # value 1 for DohFlags key means use automatic template for DoH, 2 means manual template, since we add our template to Windows, it's predefined so we use value 1
                $null = New-Item -Path $PathV4 -Force
                $null = New-ItemProperty -Path $PathV4 -Name 'DohFlags' -Value '1' -PropertyType 'Qword' -Force
            }
        }

        # Making sure the DoH server supports and has IPv6 addresses
        if ($null -ne $IPV6s) {

            Write-Verbose -Message 'Adding the new IPv6 addresses to the DoH template in Windows DoH template predefined list'
            $IPV6s | ForEach-Object -Process {

                # defining registry path for DoH settings of the $ActiveNetworkInterface based on its GUID for IPv6
                [System.String]$PathV6 = "Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Dnscache\InterfaceSpecificParameters\$($ActiveNetworkInterface.InterfaceGuid)\DohInterfaceSettings\Doh6\$_"

                Write-Verbose -Message 'Associating the new IPv6s with the selected DoH template in Windows DoH template predefined list'
                $null = Add-DnsClientDohServerAddress -ServerAddress $_ -DohTemplate $DoHTemplate -AllowFallbackToUdp $False -AutoUpgrade $True

                # add DoH settings for the specified Network adapter based on its GUID in registry
                # value 1 for DohFlags key means use automatic template for DoH, 2 means manual template, since we already added our template to Windows, it's considered predefined, so we use value 1
                $null = New-Item -Path $PathV6 -Force
                $null = New-ItemProperty -Path $PathV6 -Name 'DohFlags' -Value '1' -PropertyType 'Qword' -Force
            }
        }

        # gather IPv4s and IPv6s all in one place
        [System.Net.IPAddress[]]$NewIPs = $IPV4s + $IPV6s

        # this is responsible for making the changes in Windows settings UI > Network and internet > $ActiveNetworkInterface.Name
        Set-DnsClientServerAddress -ServerAddresses $NewIPs -InterfaceIndex $ActiveNetworkInterface.ifIndex

    }

    end {
        if ($ShouldExit) { Return }

        Write-Verbose -Message 'Clearing the DNS client cache'
        Clear-DnsClientCache

        Write-Host -Object "DNS over HTTPS has been successfully configured for $($ActiveNetworkInterface.Name) using $DoHTemplate template." -ForegroundColor Green

        # Define the name and path of the scheduled task for DDoH
        [System.String]$TaskName = 'Dynamic DoH Server IP check'
        [System.String]$TaskPath = '\DDoH\'

        if (Get-ScheduledTask -TaskName $TaskName -TaskPath $TaskPath -ErrorAction SilentlyContinue) {

            Write-Verbose -Message 'Deleting the Dynamic DoH scheduled task because it is no longer needed as a new type of DoH is being used now'

            Unregister-ScheduledTask -TaskName $TaskName -TaskPath $TaskPath -Confirm:$false
        }
    }
    <#
.SYNOPSIS
    This function is a wrapper around the official Microsoft methods to configure DNS over HTTPS in Windows
.LINK
    https://github.com/HotCakeX/WinSecureDNSMgr
.DESCRIPTION
    This script is a wrapper around the official Microsoft methods to configure DNS over HTTPS in Windows.
    f no IP address is provided for the DoH template, they will be detected automatically.
.FUNCTIONALITY
    Using official Microsoft methods configures DNS over HTTPS in Windows
.PARAMETER DoHProvider
    The name of the 3 built-in DNS over HTTPS providers: Cloudflare, Google and Quad9
.PARAMETER DoHTemplate
    Enter a custom DoH template URL that starts with https, has a TLD and a slash after it. E.g.: https://template.com/"
.PARAMETER IPV4s
    Enter 1 or 2 IPv4 and/or IPv6 addresses separated by comma
.PARAMETER IPV6s
    Enter 1 or 2 IPv4 and/or IPv6 addresses separated by comma
.PARAMETER Verbose
    Switch to enable verbose output
.EXAMPLE
    Set-CustomWinSecureDNS -DoHTemplate https://example.com/
    Set-CDOH -DoHTemplate https://example.com -IPV4s 1.2.3.4 -IPV6s 2001:db8::8a2e:370:7334
.INPUTS
    System.String
    System.Net.IPAddress[]
.OUTPUTS
    Microsoft.Management.Infrastructure.CimInstance
    System.String
#>

}