Add safe Windows desktop feed publication

Desktop/scripts/validate-desktop-update-feed.ps1

@@ -1,6 +1,10 @@
+[CmdletBinding(DefaultParameterSetName = "Url")]
 param(
-    [Parameter(Mandatory = $true)]
-    [string]$Url
+    [Parameter(Mandatory = $true, ParameterSetName = "Url")]
+    [string]$Url,
+
+    [Parameter(Mandatory = $true, ParameterSetName = "Path")]
+    [string]$Path
 )
 
 $ErrorActionPreference = "Stop"
@@ -10,27 +14,42 @@ function Fail($Message) {
     exit 1
 }
 
-$parsedUrl = $null
-if (-not [System.Uri]::TryCreate($Url, [System.UriKind]::Absolute, [ref]$parsedUrl)) {
-    Fail "Desktop update feed URL is not absolute: $Url"
-}
+$feedSource = $null
+$feedContent = $null
 
-if ($parsedUrl.Scheme -ne "https") {
-    Fail "Desktop update feed URL must use HTTPS: $Url"
+if ($PSCmdlet.ParameterSetName -eq "Url") {
+    $parsedUrl = $null
+    if (-not [System.Uri]::TryCreate($Url, [System.UriKind]::Absolute, [ref]$parsedUrl)) {
+        Fail "Desktop update feed URL is not absolute: $Url"
+    }
+
+    if ($parsedUrl.Scheme -ne "https") {
+        Fail "Desktop update feed URL must use HTTPS: $Url"
+    }
+
+    try {
+        $response = Invoke-WebRequest -Uri $Url -UseBasicParsing -TimeoutSec 30
+    } catch {
+        Fail "Desktop update feed request failed for ${Url}: $($_.Exception.Message)"
+    }
+
+    if ($response.StatusCode -ne 200) {
+        Fail "Desktop update feed must return HTTP 200. Actual status: $($response.StatusCode)"
+    }
+
+    $feedSource = $Url
+    $feedContent = $response.Content
+} else {
+    if (-not (Test-Path -LiteralPath $Path)) {
+        Fail "Desktop update feed file was not found: $Path"
+    }
+
+    $feedSource = (Resolve-Path -LiteralPath $Path).Path
+    $feedContent = Get-Content -LiteralPath $feedSource -Raw
 }
 
 try {
-    $response = Invoke-WebRequest -Uri $Url -UseBasicParsing -TimeoutSec 30
-} catch {
-    Fail "Desktop update feed request failed for ${Url}: $($_.Exception.Message)"
-}
-
-if ($response.StatusCode -ne 200) {
-    Fail "Desktop update feed must return HTTP 200. Actual status: $($response.StatusCode)"
-}
-
-try {
-    [xml]$xml = $response.Content
+    [xml]$xml = $feedContent
 } catch {
     Fail "Desktop update feed is not valid XML: $($_.Exception.Message)"
 }
@@ -82,4 +101,4 @@ if ([string]::IsNullOrWhiteSpace($version)) {
     }
 }
 
-Write-Host "QSfera Desktop update feed validation passed: $Url"
+Write-Host "QSfera Desktop update feed validation passed: $feedSource"