Adding Mullvad to DNS (#4927)

* Update dns.json

* Fix Mullvad DNS review issues

* Add Mullvad secondary resolvers

* Register DoH before changing adapter DNS

* Report DNS failures to tweak workflow

* Handle non-terminating DNS assignment failures

* Preserve DNS fallback and document Mullvad options

---------

Co-authored-by: Chris Titus <contact@christitus.com>

pester/configs.Tests.ps1

@@ -374,6 +374,17 @@ Describe "UI-rendered config entries" {
         }
     }
 
+    It "exposes every configured DNS provider in the DNS combobox" {
+        $dns = Get-WinUtilConfigObject -Name "dns"
+        $tweaks = Get-WinUtilConfigObject -Name "tweaks"
+        $comboItems = @($tweaks.WPFchangedns.ComboItems -split " ")
+        $missingProviders = @($dns.PSObject.Properties.Name | Where-Object { $comboItems -notcontains $_ })
+
+        if ($missingProviders.Count -gt 0) {
+            throw "WPFchangedns missing providers: $($missingProviders -join ', ')"
+        }
+    }
+
     It "contains required feature fields and valid configured functions" {
         $feature = Get-WinUtilConfigObject -Name "feature"
         $functionNames = Get-WinUtilTopLevelFunctionNames

pester/dns.Tests.ps1

@@ -10,7 +10,8 @@ BeforeAll {
         param(
             $InterfaceIndex,
             $ServerAddresses,
-            [switch]$ResetServerAddresses
+            [switch]$ResetServerAddresses,
+            $ErrorAction
         )
     }
     function netsh {
@@ -52,6 +53,23 @@ Describe "Set-WinUtilDNS" {
                         Secondary6 = "2606:4700:4700::1001"
                         DohTemplate = "https://cloudflare-dns.com/dns-query"
                     }
+                    Mullvad = [pscustomobject]@{
+                        Primary = "194.242.2.2"
+                        Secondary = "194.242.2.3"
+                        Primary6 = "2a07:e340::2"
+                        Secondary6 = "2a07:e340::3"
+                        DohOnly = $true
+                        DohTemplate = "https://dns.mullvad.net/dns-query"
+                        SecondaryDohTemplate = "https://adblock.dns.mullvad.net/dns-query"
+                    }
+                    MullvadNoSecondary = [pscustomobject]@{
+                        Primary = "194.242.2.2"
+                        Secondary = ""
+                        Primary6 = "2a07:e340::2"
+                        Secondary6 = ""
+                        DohOnly = $true
+                        DohTemplate = "https://dns.mullvad.net/dns-query"
+                    }
                 }
             }
         })
@@ -88,8 +106,9 @@ Describe "Set-WinUtilDNS" {
     }
 
     It "sets IPv4 and IPv6 DNS server addresses separately and applies DoH templates" {
-        Set-WinUtilDNS -DNSProvider "Cloudflare"
+        $result = Set-WinUtilDNS -DNSProvider "Cloudflare"
 
+        $result | Should -BeTrue
         Should -Invoke -CommandName Set-DnsClientServerAddress -Times 1 -Exactly -ParameterFilter {
             $InterfaceIndex -eq 7 -and
                 $ServerAddresses.Count -eq 2 -and
@@ -131,6 +150,79 @@ Describe "Set-WinUtilDNS" {
         Should -Invoke -CommandName Add-DnsClientDohServerAddress -Times 3 -Exactly
     }
 
+    It "filters empty DNS server addresses" {
+        Set-WinUtilDNS -DNSProvider "MullvadNoSecondary"
+
+        Should -Invoke -CommandName Set-DnsClientServerAddress -Times 1 -Exactly -ParameterFilter {
+            $InterfaceIndex -eq 7 -and
+                $ServerAddresses.Count -eq 1 -and
+                $ServerAddresses[0] -eq "194.242.2.2"
+        }
+        Should -Invoke -CommandName Set-DnsClientServerAddress -Times 1 -Exactly -ParameterFilter {
+            $InterfaceIndex -eq 7 -and
+                $ServerAddresses.Count -eq 1 -and
+                $ServerAddresses[0] -eq "2a07:e340::2"
+        }
+        Should -Invoke -CommandName Add-DnsClientDohServerAddress -Times 2 -Exactly
+    }
+
+    It "applies the matching DoH template to secondary resolvers" {
+        Set-WinUtilDNS -DNSProvider "Mullvad"
+
+        Should -Invoke -CommandName Add-DnsClientDohServerAddress -Times 2 -Exactly -ParameterFilter {
+            $ServerAddress -in @("194.242.2.2", "2a07:e340::2") -and
+                $DohTemplate -eq "https://dns.mullvad.net/dns-query"
+        }
+        Should -Invoke -CommandName Add-DnsClientDohServerAddress -Times 2 -Exactly -ParameterFilter {
+            $ServerAddress -in @("194.242.2.3", "2a07:e340::3") -and
+                $DohTemplate -eq "https://adblock.dns.mullvad.net/dns-query"
+        }
+    }
+
+    It "does not apply a DoH-only provider when DoH is unsupported" {
+        Mock Get-Command { return $null } -ParameterFilter { $Name -eq "Add-DnsClientDohServerAddress" }
+
+        $result = Set-WinUtilDNS -DNSProvider "Mullvad"
+
+        $result | Should -BeFalse
+        Should -Invoke -CommandName Set-DnsClientServerAddress -Times 0 -Exactly
+        Should -Invoke -CommandName Add-DnsClientDohServerAddress -Times 0 -Exactly
+        Should -Invoke -CommandName Write-Warning -Times 1 -Exactly -ParameterFilter {
+            $Message -eq "DNS provider Mullvad requires DNS over HTTPS, which is not supported on this system."
+        }
+    }
+
+    It "does not change adapter DNS when DoH registration fails" {
+        Mock Add-DnsClientDohServerAddress { throw "DoH registration failed" }
+
+        $result = Set-WinUtilDNS -DNSProvider "Mullvad"
+
+        $result | Should -BeFalse
+        Should -Invoke -CommandName Set-DnsClientServerAddress -Times 0 -Exactly
+        Should -Invoke -CommandName Write-WinUtilLog -Times 1 -Exactly -ParameterFilter {
+            $Level -eq "ERROR" -and
+                $Component -eq "DNS" -and
+                $Message -like "DNS provider Mullvad was not completed: *"
+        }
+    }
+
+    It "falls back to plain DNS when optional DoH registration fails" {
+        Mock Add-DnsClientDohServerAddress { throw "DoH registration failed" }
+
+        $result = Set-WinUtilDNS -DNSProvider "Cloudflare"
+
+        $result | Should -BeTrue
+        Should -Invoke -CommandName Set-DnsClientServerAddress -Times 2 -Exactly
+        Should -Invoke -CommandName Write-Warning -Times 1 -Exactly -ParameterFilter {
+            $Message -eq "DNS over HTTPS setup for provider Cloudflare failed; continuing with plain DNS."
+        }
+        Should -Invoke -CommandName Write-WinUtilLog -Times 1 -Exactly -ParameterFilter {
+            $Level -eq "WARN" -and
+                $Component -eq "DNS" -and
+                $Message -like "DNS over HTTPS setup for provider Cloudflare failed; continuing with plain DNS: *"
+        }
+    }
+
     It "resets DNS to DHCP and removes the applied DoH configuration" {
         Mock Test-Path { return $true } -ParameterFilter { $Path -like "*DohInterfaceSettings*" }
         Mock Get-ChildItem {
@@ -178,15 +270,23 @@ Describe "Set-WinUtilDNS" {
         Should -Invoke -CommandName Remove-DnsClientDohServerAddress -Times 4 -Exactly
     }
 
-    It "catches DNS setter failures so the tweak runspace can continue" {
-        Mock Set-DnsClientServerAddress { throw "DNS failed" }
+    It "catches non-terminating DNS setter failures so the tweak runspace can continue" {
+        Mock Set-DnsClientServerAddress { Write-Error "DNS failed" -ErrorAction $ErrorAction }
 
-        { Set-WinUtilDNS -DNSProvider "Cloudflare" } | Should -Not -Throw
+        $result = Set-WinUtilDNS -DNSProvider "Cloudflare"
 
+        $result | Should -BeFalse
         Should -Invoke -CommandName Write-WinUtilLog -Times 1 -Exactly -ParameterFilter {
             $Level -eq "ERROR" -and
                 $Component -eq "DNS" -and
                 $Message -like "DNS provider Cloudflare was not completed: *"
         }
     }
+
+    It "returns failure for an unknown DNS provider" {
+        $result = Set-WinUtilDNS -DNSProvider "Unknown"
+
+        $result | Should -BeFalse
+        Should -Invoke -CommandName Set-DnsClientServerAddress -Times 0 -Exactly
+    }
 }

pester/tweaks.Tests.ps1

@@ -181,9 +181,14 @@ Describe "Invoke-WPFtweaksbutton" {
                 text = "Cloudflare"
             }
         })
+        $script:capturedTweaksScriptBlock = $null
 
-        Mock Invoke-WPFRunspace { [pscustomobject]@{ MockHandle = $true } }
+        Mock Invoke-WPFRunspace {
+            $script:capturedTweaksScriptBlock = $ScriptBlock
+            [pscustomobject]@{ MockHandle = $true }
+        }
         Mock Invoke-WinUtilTweaks { }
+        Mock Set-WinUtilTweaksProgressIndicator { }
         Mock Invoke-WPFUIThread { }
         Mock Write-WinUtilLog { }
         Mock Write-Host { }
@@ -191,6 +196,7 @@ Describe "Invoke-WPFtweaksbutton" {
 
     AfterEach {
         Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name capturedTweaksScriptBlock -Scope Script -ErrorAction SilentlyContinue
     }
 
     It "passes selected tweaks, DNS provider, and progress counters to the tweak runspace" {
@@ -236,4 +242,26 @@ Describe "Invoke-WPFtweaksbutton" {
                 $ParameterList[3][1] -eq 2
         }
     }
+
+    It "stops the tweak workflow when the DNS change fails" {
+        $script:sync.selectedTweaks.Add("WPFTweaksTelemetry")
+        Mock Set-WinUtilDNS { return $false }
+
+        Invoke-WPFtweaksbutton
+        & $script:capturedTweaksScriptBlock -tweaks @("WPFTweaksTelemetry") -dnsProvider "Mullvad" -completedSteps 0 -totalSteps 1
+
+        Should -Invoke -CommandName Invoke-WinUtilTweaks -Times 0 -Exactly
+        Should -Invoke -CommandName Set-WinUtilTweaksProgressIndicator -Times 1 -Exactly -ParameterFilter {
+            $Visible -eq $true -and $Label -eq "DNS change failed" -and $Percent -eq 100
+        }
+        Should -Invoke -CommandName Invoke-WPFUIThread -Times 1 -Exactly -ParameterFilter {
+            $ScriptBlock.ToString() -like '*Set-WinUtilTaskbaritem -state "Error" -overlay "warning"*'
+        }
+        Should -Invoke -CommandName Write-WinUtilLog -Times 1 -Exactly -ParameterFilter {
+            $Level -eq "ERROR" -and
+                $Component -eq "Tweaks" -and
+                $Message -eq "Tweaks workflow stopped because the DNS change failed."
+        }
+        $script:sync.ProcessRunning | Should -BeFalse
+    }
 }