Fix decompression in web cmdlets (PowerShell#17955)

Author: iSazonov

src/Microsoft.PowerShell.Commands.Utility/commands/utility/WebCmdlet/Common/WebRequestPSCmdlet.Common.cs

@@ -992,9 +992,9 @@ private HttpMethod GetHttpMethod(WebRequestMethod method)
         // and PreserveAuthorizationOnRedirect is NOT set.
         internal virtual HttpClient GetHttpClient(bool handleRedirect)
         {
-            // By default the HttpClientHandler will automatically decompress GZip and Deflate content
             HttpClientHandler handler = new();
             handler.CookieContainer = WebSession.Cookies;
+            handler.AutomaticDecompression = DecompressionMethods.All;
 
             // set the credentials used by this request
             if (WebSession.UseDefaultCredentials)

src/Microsoft.PowerShell.Commands.Utility/commands/utility/WebCmdlet/StreamHelper.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.IO;
-using System.IO.Compression;
 using System.Management.Automation;
 using System.Management.Automation.Internal;
 using System.Net.Http;
@@ -502,21 +501,6 @@ internal static byte[] EncodeToBytes(string str)
         internal static Stream GetResponseStream(HttpResponseMessage response)
         {
             Stream responseStream = response.Content.ReadAsStreamAsync().GetAwaiter().GetResult();
-            var contentEncoding = response.Content.Headers.ContentEncoding;
-
-            // HttpClient by default will automatically decompress GZip and Deflate content.
-            // We keep this decompression logic here just in case.
-            if (contentEncoding != null && contentEncoding.Count > 0)
-            {
-                if (contentEncoding.Contains("gzip"))
-                {
-                    responseStream = new GZipStream(responseStream, CompressionMode.Decompress);
-                }
-                else if (contentEncoding.Contains("deflate"))
-                {
-                    responseStream = new DeflateStream(responseStream, CompressionMode.Decompress);
-                }
-            }
 
             return responseStream;
         }

test/powershell/Modules/Microsoft.PowerShell.Utility/WebCmdlets.Tests.ps1

@@ -587,8 +587,8 @@ Describe "Invoke-WebRequest tests" -Tags "Feature", "RequireAdminOnWindows" {
     # $dataEncodings = @("Chunked", "Compress", "Deflate", "GZip", "Identity")
     # Note: These are the supported options, but we do not have a web service to test them all.
     It "Invoke-WebRequest supports request that returns <DataEncoding>-encoded data." -TestCases @(
-        @{ DataEncoding = "gzip"}
-        @{ DataEncoding = "deflate"}
+        @{ DataEncoding = "gzip" }
+        @{ DataEncoding = "deflate" }
     ) {
         param($dataEncoding)
         $uri = Get-WebListenerUrl -Test 'Compression' -TestValue $dataEncoding
@@ -598,7 +598,7 @@ Describe "Invoke-WebRequest tests" -Tags "Feature", "RequireAdminOnWindows" {
         ValidateResponse -response $result
 
         # Validate response content
-        $result.Output.Headers.'Content-Encoding'[0] | Should -BeExactly $dataEncoding
+        # The content should be de-compressed, and otherwise converting from JSON will fail.
         $jsonContent = $result.Output.Content | ConvertFrom-Json
         $jsonContent.Headers.Host | Should -BeExactly $uri.Authority
     }
@@ -2246,15 +2246,15 @@ Describe "Invoke-RestMethod tests" -Tags "Feature", "RequireAdminOnWindows" {
     # $dataEncodings = @("Chunked", "Compress", "Deflate", "GZip", "Identity")
     # Note: These are the supported options, but we do not have a web service to test them all.
     It "Invoke-RestMethod supports request that returns <DataEncoding>-encoded data." -TestCases @(
-        @{ DataEncoding = "gzip"}
-        @{ DataEncoding = "deflate"}
+        @{ DataEncoding = "gzip" }
+        @{ DataEncoding = "deflate" }
     ) {
         param($dataEncoding)
         $uri = Get-WebListenerUrl -Test 'Compression' -TestValue $dataEncoding
-        $result = Invoke-RestMethod -Uri $uri -ResponseHeadersVariable 'headers'
+        $result = Invoke-RestMethod -Uri $uri
 
         # Validate response content
-        $headers.'Content-Encoding'[0] | Should -BeExactly $dataEncoding
+        # The content should be de-compressed. Otherwise, the above 'Invoke-RestMethod' would have thrown because converting to JSON internally would fail.
         $result.Headers.Host | Should -BeExactly $uri.Authority
     }