[WinHTTP] remove unnecessary manual decompression (#114778)

* Remove obsoleted manual decompression that existed only for already unsupported Win 8.1-

* Remove obsolete unit tests

Author: ManickaP

src/libraries/System.Net.Http.WinHttpHandler/src/System/Net/Http/WinHttpHandler.cs

@@ -46,8 +46,6 @@ public class WinHttpHandler : HttpMessageHandler
         internal static bool CertificateCachingAppContextSwitchEnabled { get; } = AppContext.TryGetSwitch("System.Net.Http.UseWinHttpCertificateCaching", out bool enabled) && enabled;
         private static readonly TimeSpan s_maxTimeout = TimeSpan.FromMilliseconds(int.MaxValue);
 
-        private static readonly StringWithQualityHeaderValue s_gzipHeaderValue = new StringWithQualityHeaderValue("gzip");
-        private static readonly StringWithQualityHeaderValue s_deflateHeaderValue = new StringWithQualityHeaderValue("deflate");
         private static readonly Lazy<bool> s_supportsTls13 = new Lazy<bool>(CheckTls13Support);
         private static readonly TimeSpan s_cleanCachedCertificateTimeout = TimeSpan.FromMilliseconds((int?)AppDomain.CurrentDomain.GetData("System.Net.Http.WinHttpCertificateCachingCleanupTimerInterval") ?? 60_000);
         private static readonly long s_staleTimeout = (long)(s_cleanCachedCertificateTimeout.TotalSeconds * Stopwatch.Frequency / 1000);
@@ -56,7 +54,6 @@ public class WinHttpHandler : HttpMessageHandler
         private static StringBuilder? t_requestHeadersBuilder;
 
         private readonly object _lockObject = new object();
-        private bool _doManualDecompressionCheck;
         private bool _automaticRedirection = HttpHandlerDefaults.DefaultAutomaticRedirection;
         private int _maxAutomaticRedirections = HttpHandlerDefaults.DefaultMaxAutomaticRedirections;
         private DecompressionMethods _automaticDecompression = HttpHandlerDefaults.DefaultAutomaticDecompression;
@@ -715,8 +712,7 @@ private static WinHttpChunkMode GetChunkedModeForSend(HttpRequestMessage request
         private static void AddRequestHeaders(
             SafeWinHttpHandle requestHandle,
             HttpRequestMessage requestMessage,
-            CookieContainer? cookies,
-            DecompressionMethods manuallyProcessedDecompressionMethods)
+            CookieContainer? cookies)
         {
             Debug.Assert(requestMessage.RequestUri != null);
 
@@ -732,26 +728,6 @@ private static void AddRequestHeaders(
                 t_requestHeadersBuilder = requestHeadersBuffer = new StringBuilder();
             }
 
-            // Normally WinHttpHandler will let native WinHTTP add 'Accept-Encoding' request headers
-            // for gzip and/or default as needed based on whether the handler should do automatic
-            // decompression of response content. But on Windows 7, WinHTTP doesn't support this feature.
-            // So, we need to manually add these headers since WinHttpHandler still supports automatic
-            // decompression (by doing it within the handler).
-            if (manuallyProcessedDecompressionMethods != DecompressionMethods.None)
-            {
-                if ((manuallyProcessedDecompressionMethods & DecompressionMethods.GZip) == DecompressionMethods.GZip &&
-                    !requestMessage.Headers.AcceptEncoding.Contains(s_gzipHeaderValue))
-                {
-                    requestMessage.Headers.AcceptEncoding.Add(s_gzipHeaderValue);
-                }
-
-                if ((manuallyProcessedDecompressionMethods & DecompressionMethods.Deflate) == DecompressionMethods.Deflate &&
-                    !requestMessage.Headers.AcceptEncoding.Contains(s_deflateHeaderValue))
-                {
-                    requestMessage.Headers.AcceptEncoding.Add(s_deflateHeaderValue);
-                }
-            }
-
             // Manually add cookies.
             if (cookies != null && cookies.Count > 0)
             {
@@ -941,8 +917,7 @@ private async Task StartRequestAsync(WinHttpRequestState state)
                 AddRequestHeaders(
                     state.RequestHandle,
                     state.RequestMessage,
-                    _cookieUsePolicy == CookieUsePolicy.UseSpecifiedCookieContainer ? _cookieContainer : null,
-                    _doManualDecompressionCheck ? _automaticDecompression : DecompressionMethods.None);
+                    _cookieUsePolicy == CookieUsePolicy.UseSpecifiedCookieContainer ? _cookieContainer : null);
 
                 uint proxyAuthScheme = 0;
                 uint serverAuthScheme = 0;
@@ -1027,8 +1002,7 @@ private async Task StartRequestAsync(WinHttpRequestState state)
                 uint optionData = (uint)(int)_receiveDataTimeout.TotalMilliseconds;
                 SetWinHttpOption(state.RequestHandle, Interop.WinHttp.WINHTTP_OPTION_RECEIVE_TIMEOUT, ref optionData);
 
-                HttpResponseMessage responseMessage =
-                    WinHttpResponseParser.CreateResponseMessage(state, _doManualDecompressionCheck ? _automaticDecompression : DecompressionMethods.None);
+                HttpResponseMessage responseMessage = WinHttpResponseParser.CreateResponseMessage(state);
                 state.Tcs.TrySetResult(responseMessage);
 
                 // HttpStatusCode cast is needed for 308 Moved Permenantly, which we support but is not included in NetStandard status codes.
@@ -1372,22 +1346,7 @@ private void SetRequestHandleDecompressionOptions(SafeWinHttpHandle requestHandl
                     optionData |= Interop.WinHttp.WINHTTP_DECOMPRESSION_FLAG_DEFLATE;
                 }
 
-                try
-                {
-                    SetWinHttpOption(requestHandle, Interop.WinHttp.WINHTTP_OPTION_DECOMPRESSION, ref optionData);
-                }
-                catch (WinHttpException ex)
-                {
-                    if (ex.NativeErrorCode != (int)Interop.WinHttp.ERROR_WINHTTP_INVALID_OPTION)
-                    {
-                        throw;
-                    }
-
-                    // We are running on a platform earlier than Win8.1 for which WINHTTP.DLL
-                    // doesn't support this option.  So, we'll have to do the decompression
-                    // manually.
-                    _doManualDecompressionCheck = true;
-                }
+                SetWinHttpOption(requestHandle, Interop.WinHttp.WINHTTP_OPTION_DECOMPRESSION, ref optionData);
             }
         }
 

src/libraries/System.Net.Http.WinHttpHandler/src/System/Net/Http/WinHttpResponseParser.cs

@@ -15,12 +15,7 @@ namespace System.Net.Http
 {
     internal static class WinHttpResponseParser
     {
-        private const string EncodingNameDeflate = "DEFLATE";
-        private const string EncodingNameGzip = "GZIP";
-
-        public static HttpResponseMessage CreateResponseMessage(
-            WinHttpRequestState state,
-            DecompressionMethods manuallyProcessedDecompressionMethods)
+        public static HttpResponseMessage CreateResponseMessage(WinHttpRequestState state)
         {
             HttpRequestMessage? request = state.RequestMessage;
             SafeWinHttpHandle? requestHandle = state.RequestHandle;
@@ -65,35 +60,7 @@ public static HttpResponseMessage CreateResponseMessage(
                 // Create response stream and wrap it in a StreamContent object.
                 var responseStream = new WinHttpResponseStream(requestHandle, state, response);
                 state.RequestHandle = null; // ownership successfully transferred to WinHttpResponseStream.
-                Stream decompressedStream = responseStream;
-
-                if (manuallyProcessedDecompressionMethods != DecompressionMethods.None)
-                {
-                    int contentEncodingStartIndex = 0;
-                    int contentEncodingLength = GetResponseHeader(
-                        requestHandle,
-                        Interop.WinHttp.WINHTTP_QUERY_CONTENT_ENCODING,
-                        buffer);
-
-                    ReadOnlySpan<char> value = new ReadOnlySpan<char>(buffer, contentEncodingStartIndex, contentEncodingLength).Trim();
-                    if (!value.IsEmpty)
-                    {
-                        if ((manuallyProcessedDecompressionMethods & DecompressionMethods.GZip) == DecompressionMethods.GZip &&
-                            value.Equals(EncodingNameGzip.AsSpan(), StringComparison.OrdinalIgnoreCase))
-                        {
-                            decompressedStream = new GZipStream(responseStream, CompressionMode.Decompress);
-                            stripEncodingHeaders = true;
-                        }
-                        else if ((manuallyProcessedDecompressionMethods & DecompressionMethods.Deflate) == DecompressionMethods.Deflate &&
-                                 value.Equals(EncodingNameDeflate.AsSpan(), StringComparison.OrdinalIgnoreCase))
-                        {
-                            decompressedStream = new DeflateStream(responseStream, CompressionMode.Decompress);
-                            stripEncodingHeaders = true;
-                        }
-                    }
-                }
-
-                response.Content = new NoWriteNoSeekStreamContent(decompressedStream);
+                response.Content = new NoWriteNoSeekStreamContent(responseStream);
                 response.RequestMessage = request;
 
                 // Parse raw response headers and place them into response message.

src/libraries/System.Net.Http.WinHttpHandler/tests/UnitTests/FakeInterop.cs

@@ -474,12 +474,6 @@ public static bool WinHttpSetOption(
             ref uint optionData,
             uint optionLength = sizeof(uint))
         {
-            if (option == Interop.WinHttp.WINHTTP_OPTION_DECOMPRESSION & !TestControl.WinHttpDecompressionSupport)
-            {
-                TestControl.LastWin32Error = (int)Interop.WinHttp.ERROR_WINHTTP_INVALID_OPTION;
-                return false;
-            }
-
             if (option == Interop.WinHttp.WINHTTP_OPTION_DISABLE_FEATURE &&
                 optionData == Interop.WinHttp.WINHTTP_DISABLE_COOKIES)
             {

src/libraries/System.Net.Http.WinHttpHandler/tests/UnitTests/TestControl.cs

@@ -17,8 +17,6 @@ public static class TestControl
 
         public static int LastWin32Error { get; set; }
 
-        public static bool WinHttpDecompressionSupport { get; set; }
-
         public static bool PACFileNotDetectedOnNetwork { get; set; }
 
         public static X509Certificate2Collection CurrentUserCertificateStore{ get; set; }
@@ -31,8 +29,6 @@ public static void Reset()
             WinHttpReceiveResponse = new ApiControl();
             WinHttpWriteData = new ApiControl();
 
-            WinHttpDecompressionSupport = true;
-
             LastWin32Error = 0;
 
             PACFileNotDetectedOnNetwork = false;

src/libraries/System.Net.Http.WinHttpHandler/tests/UnitTests/WinHttpHandlerTest.cs

@@ -687,100 +687,6 @@ public async Task SendAsync_PostNoContentObjectWithChunkedEncodingHeader_ExpectH
             }
         }
 
-        [Fact]
-        public async Task SendAsync_NoWinHttpDecompressionSupportAndResponseBodyIsDeflateCompressed_ExpectedResponse()
-        {
-            TestControl.WinHttpDecompressionSupport = false;
-            var handler = new WinHttpHandler();
-
-            using (HttpResponseMessage response = SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
-                    TestServer.SetResponse(DecompressionMethods.Deflate, TestServer.ExpectedResponseBody);
-                }))
-            {
-                await VerifyResponseContent(
-                    TestServer.ExpectedResponseBodyBytes,
-                    response.Content,
-                    responseContentWasOriginallyCompressed: true,
-                    responseContentWasAutoDecompressed: true);
-            }
-        }
-
-        [Fact]
-        public async Task SendAsync_NoWinHttpDecompressionSupportAndResponseBodyIsGZipCompressed_ExpectedResponse()
-        {
-            TestControl.WinHttpDecompressionSupport = false;
-            var handler = new WinHttpHandler();
-
-            using (HttpResponseMessage response = SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
-                    TestServer.SetResponse(DecompressionMethods.GZip, TestServer.ExpectedResponseBody);
-                }))
-            {
-                await VerifyResponseContent(
-                    TestServer.ExpectedResponseBodyBytes,
-                    response.Content,
-                    responseContentWasOriginallyCompressed: true,
-                    responseContentWasAutoDecompressed: true);
-            }
-        }
-
-        [Fact]
-        public async Task SendAsync_NoWinHttpDecompressionSupportAndResponseBodyIsNotCompressed_ExpectedResponse()
-        {
-            TestControl.WinHttpDecompressionSupport = false;
-            var handler = new WinHttpHandler();
-
-            using (HttpResponseMessage response = SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.WindowsProxyUsePolicy = WindowsProxyUsePolicy.UseWinInetProxy;
-                }))
-            {
-                await VerifyResponseContent(
-                    TestServer.ExpectedResponseBodyBytes,
-                    response.Content,
-                    responseContentWasOriginallyCompressed: false,
-                    responseContentWasAutoDecompressed: false);
-
-            }
-        }
-
-        [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public async Task SendAsync_NoWinHttpDecompressionSupport_AutoDecompressionSettingDiffers_ResponseIsNotDecompressed(bool responseIsGZip)
-        {
-            DecompressionMethods decompressionMethods = responseIsGZip ? DecompressionMethods.Deflate : DecompressionMethods.GZip;
-            _output.WriteLine("DecompressionMethods = {0}", decompressionMethods.ToString());
-
-            TestControl.WinHttpDecompressionSupport = false;
-            var handler = new WinHttpHandler();
-
-            using (HttpResponseMessage response = SendRequestHelper.Send(
-                handler,
-                delegate
-                {
-                    handler.AutomaticDecompression = decompressionMethods;
-                    TestServer.SetResponse(responseIsGZip ? DecompressionMethods.GZip : DecompressionMethods.Deflate, TestServer.ExpectedResponseBody);
-                }))
-            {
-                await VerifyResponseContent(
-                    TestServer.CompressBytes(TestServer.ExpectedResponseBodyBytes, useGZip: responseIsGZip),
-                    response.Content,
-                    responseContentWasOriginallyCompressed: true,
-                    responseContentWasAutoDecompressed: false);
-
-            }
-        }
-
         [Fact]
         public void SendAsync_AutomaticProxySupportAndUseWinInetSettings_ExpectedWinHttpSessionProxySettings()
         {
@@ -931,40 +837,6 @@ public void SendAsync_MultipleCallsWithDispose_NoHandleLeaksManuallyVerifiedUsin
             }
         }
 
-        private async Task VerifyResponseContent(
-            byte[] expectedResponseBodyBytes,
-            HttpContent responseContent,
-            bool responseContentWasOriginallyCompressed,
-            bool responseContentWasAutoDecompressed)
-        {
-            Nullable<long> contentLength = responseContent.Headers.ContentLength;
-            ICollection<string> contentEncoding = responseContent.Headers.ContentEncoding;
-
-            _output.WriteLine("Response Content.Headers.ContentLength = {0}", contentLength.HasValue ? contentLength.Value.ToString() : "(null)");
-            _output.WriteLine("Response Content.Headers.ContentEncoding = {0}", contentEncoding.Count > 0 ? contentEncoding.ToString() : "(null)");
-            byte[] responseBodyBytes = await responseContent.ReadAsByteArrayAsync();
-            _output.WriteLine($"Response Body          = {BitConverter.ToString(responseBodyBytes)}");
-            _output.WriteLine($"Expected Response Body = {BitConverter.ToString(expectedResponseBodyBytes)}");
-
-            if (!responseContentWasOriginallyCompressed)
-            {
-                Assert.True(contentLength > 0);
-            }
-            else if (responseContentWasAutoDecompressed)
-            {
-
-                Assert.Null(contentLength);
-                Assert.Equal(0, contentEncoding.Count);
-            }
-            else
-            {
-                Assert.True(contentLength > 0);
-                Assert.True(contentEncoding.Count > 0);
-            }
-
-            Assert.Equal<byte>(expectedResponseBodyBytes, responseBodyBytes);
-        }
-
         // Commented out as the test relies on finalizer for cleanup and only has value as written
         // when run on its own and manual analysis is done of logs.
         //[Fact]