WinHttpHandler: Read HTTP/2 trailing headers

Fixes dotnet#44778

src/libraries/Common/src/Interop/Windows/WinHttp/Interop.winhttp_types.cs

@@ -68,6 +68,7 @@ internal partial class WinHttp
         public const uint WINHTTP_QUERY_STATUS_TEXT = 20;
         public const uint WINHTTP_QUERY_RAW_HEADERS = 21;
         public const uint WINHTTP_QUERY_RAW_HEADERS_CRLF = 22;
+        public const uint WINHTTP_QUERY_FLAG_TRAILERS = 0x02000000;
         public const uint WINHTTP_QUERY_CONTENT_ENCODING = 29;
         public const uint WINHTTP_QUERY_SET_COOKIE = 43;
         public const uint WINHTTP_QUERY_CUSTOM = 65535;
@@ -164,6 +165,7 @@ internal partial class WinHttp
         public const uint WINHTTP_OPTION_WEB_SOCKET_SEND_BUFFER_SIZE = 123;
 
         public const uint WINHTTP_OPTION_TCP_KEEPALIVE = 152;
+        public const uint WINHTTP_OPTION_STREAM_ERROR_CODE = 159;
 
         public enum WINHTTP_WEB_SOCKET_BUFFER_TYPE
         {

src/libraries/Common/src/System/Net/SecurityProtocol.cs

@@ -8,7 +8,7 @@ namespace System.Net
     internal static class SecurityProtocol
     {
         public const SslProtocols DefaultSecurityProtocols =
-#if !NETSTANDARD2_0 && !NETFRAMEWORK
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1 && !NETFRAMEWORK
             SslProtocols.Tls13 |
 #endif
             SslProtocols.Tls | SslProtocols.Tls11 | SslProtocols.Tls12;

src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs

@@ -137,7 +137,7 @@ public static bool IsNonZeroLowerBoundArraySupported
         // OSX - SecureTransport doesn't expose alpn APIs. TODO https://github.com/dotnet/runtime/issues/27727
         public static bool IsOpenSslSupported => IsLinux || IsFreeBSD || Isillumos || IsSolaris;
 
-        public static bool SupportsAlpn => (IsWindows && !IsWindows7) ||
+        public static bool SupportsAlpn => (IsWindows && !IsWindows7 && !IsNetFramework) ||
             (IsOpenSslSupported &&
             (OpenSslVersion.Major >= 1 && (OpenSslVersion.Minor >= 1 || OpenSslVersion.Build >= 2)));
 

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

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <IncludeDllSafeSearchPathAttribute>true</IncludeDllSafeSearchPathAttribute>
-    <TargetFrameworks>netstandard2.0-windows;netstandard2.0;net461-windows</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0-windows;netstandard2.0;netstandard2.1-windows;netstandard2.1;net461-windows</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <Nullable>enable</Nullable>
   </PropertyGroup>
@@ -94,6 +94,7 @@
     <Compile Include="System\Net\Http\WinHttpResponseParser.cs" />
     <Compile Include="System\Net\Http\WinHttpResponseStream.cs" />
     <Compile Include="System\Net\Http\WinHttpTraceHelper.cs" />
+    <Compile Include="System\Net\Http\WinHttpTrailersHelper.cs" />
     <Compile Include="System\Net\Http\WinHttpTransportContext.cs" />
     <Compile Include="$(CommonPath)System\IO\StreamHelpers.CopyValidation.cs"
              Link="Common\System\IO\StreamHelpers.CopyValidation.cs" />

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

@@ -29,7 +29,7 @@ public static HttpResponseMessage CreateResponseMessage(
             // Create a single buffer to use for all subsequent WinHttpQueryHeaders string interop calls.
             // This buffer is the length needed for WINHTTP_QUERY_RAW_HEADERS_CRLF, which includes the status line
             // and all headers separated by CRLF, so it should be large enough for any individual status line or header queries.
-            int bufferLength = GetResponseHeaderCharBufferLength(requestHandle, Interop.WinHttp.WINHTTP_QUERY_RAW_HEADERS_CRLF);
+            int bufferLength = GetResponseHeaderCharBufferLength(requestHandle, isTrailingHeaders: false);
             char[] buffer = ArrayPool<char>.Shared.Rent(bufferLength);
             try
             {
@@ -58,7 +58,7 @@ public static HttpResponseMessage CreateResponseMessage(
                     string.Empty;
 
                 // Create response stream and wrap it in a StreamContent object.
-                var responseStream = new WinHttpResponseStream(requestHandle, state);
+                var responseStream = new WinHttpResponseStream(requestHandle, state, response);
                 state.RequestHandle = null; // ownership successfully transfered to WinHttpResponseStram.
                 Stream decompressedStream = responseStream;
 
@@ -223,19 +223,26 @@ private static unsafe int GetResponseHeader(SafeWinHttpHandle requestHandle, uin
         /// <summary>
         /// Returns the size of the char array buffer.
         /// </summary>
-        private static unsafe int GetResponseHeaderCharBufferLength(SafeWinHttpHandle requestHandle, uint infoLevel)
+        public static unsafe int GetResponseHeaderCharBufferLength(SafeWinHttpHandle requestHandle, bool isTrailingHeaders)
         {
             char* buffer = null;
             int bufferLength = 0;
             uint index = 0;
 
+            uint infoLevel = Interop.WinHttp.WINHTTP_QUERY_RAW_HEADERS_CRLF;
+            if (isTrailingHeaders)
+            {
+                infoLevel |= Interop.WinHttp.WINHTTP_QUERY_FLAG_TRAILERS;
+            }
+
             if (!QueryHeaders(requestHandle, infoLevel, buffer, ref bufferLength, ref index))
             {
                 int lastError = Marshal.GetLastWin32Error();
 
-                Debug.Assert(lastError != Interop.WinHttp.ERROR_WINHTTP_HEADER_NOT_FOUND);
+                Debug.Assert(isTrailingHeaders || lastError != Interop.WinHttp.ERROR_WINHTTP_HEADER_NOT_FOUND);
 
-                if (lastError != Interop.WinHttp.ERROR_INSUFFICIENT_BUFFER)
+                if (lastError != Interop.WinHttp.ERROR_INSUFFICIENT_BUFFER &&
+                    (!isTrailingHeaders || lastError != Interop.WinHttp.ERROR_WINHTTP_HEADER_NOT_FOUND))
                 {
                     throw WinHttpException.CreateExceptionUsingError(lastError, nameof(Interop.WinHttp.WinHttpQueryHeaders));
                 }
@@ -306,10 +313,7 @@ private static void ParseResponseHeaders(
             reader.ReadLine();
 
             // Parse the array of headers and split them between Content headers and Response headers.
-            string headerName;
-            string headerValue;
-
-            while (reader.ReadHeader(out headerName, out headerValue))
+            while (reader.ReadHeader(out string headerName, out string headerValue))
             {
                 if (!responseHeaders.TryAddWithoutValidation(headerName, headerValue))
                 {
@@ -331,6 +335,27 @@ private static void ParseResponseHeaders(
             }
         }
 
+        public static void ParseResponseTrailers(
+            SafeWinHttpHandle requestHandle,
+            HttpResponseMessage response,
+            char[] buffer)
+        {
+            HttpHeaders responseTrailers = WinHttpTrailersHelper.GetResponseTrailers(response);
+
+            int bufferLength = GetResponseHeader(
+                requestHandle,
+                Interop.WinHttp.WINHTTP_QUERY_RAW_HEADERS_CRLF | Interop.WinHttp.WINHTTP_QUERY_FLAG_TRAILERS,
+                buffer);
+
+            var reader = new WinHttpResponseHeaderReader(buffer, 0, bufferLength);
+
+            // Parse the array of headers and split them between Content headers and Response headers.
+            while (reader.ReadHeader(out string headerName, out string headerValue))
+            {
+                responseTrailers.TryAddWithoutValidation(headerName, headerValue);
+            }
+        }
+
         private static bool IsResponseHttp2(SafeWinHttpHandle requestHandle)
         {
             uint data = 0;

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

@@ -16,11 +16,14 @@ internal sealed class WinHttpResponseStream : Stream
     {
         private volatile bool _disposed;
         private readonly WinHttpRequestState _state;
+        private readonly HttpResponseMessage _responseMessage;
         private SafeWinHttpHandle _requestHandle;
+        private bool _readTrailingHeaders;
 
-        internal WinHttpResponseStream(SafeWinHttpHandle requestHandle, WinHttpRequestState state)
+        internal WinHttpResponseStream(SafeWinHttpHandle requestHandle, WinHttpRequestState state, HttpResponseMessage responseMessage)
         {
             _state = state;
+            _responseMessage = responseMessage;
             _requestHandle = requestHandle;
         }
 
@@ -126,6 +129,7 @@ private async Task CopyToAsyncCore(Stream destination, byte[] buffer, Cancellati
                     int bytesAvailable = await _state.LifecycleAwaitable;
                     if (bytesAvailable == 0)
                     {
+                        ReadResponseTrailers();
                         break;
                     }
                     Debug.Assert(bytesAvailable > 0);
@@ -142,12 +146,17 @@ private async Task CopyToAsyncCore(Stream destination, byte[] buffer, Cancellati
                     int bytesRead = await _state.LifecycleAwaitable;
                     if (bytesRead == 0)
                     {
+                        ReadResponseTrailers();
                         break;
                     }
                     Debug.Assert(bytesRead > 0);
 
                     // Write that data out to the output stream
+#if NETSTANDARD2_1
+                    await destination.WriteAsync(buffer.AsMemory(0, bytesRead), cancellationToken).ConfigureAwait(false);
+#else
                     await destination.WriteAsync(buffer, 0, bytesRead, cancellationToken).ConfigureAwait(false);
+#endif
                 }
             }
             finally
@@ -240,7 +249,14 @@ private async Task<int> ReadAsyncCore(byte[] buffer, int offset, int count, Canc
                     }
                 }
 
-                return await _state.LifecycleAwaitable;
+                int bytesRead = await _state.LifecycleAwaitable;
+
+                if (bytesRead == 0)
+                {
+                    ReadResponseTrailers();
+                }
+
+                return bytesRead;
             }
             finally
             {
@@ -249,6 +265,35 @@ private async Task<int> ReadAsyncCore(byte[] buffer, int offset, int count, Canc
             }
         }
 
+        private void ReadResponseTrailers()
+        {
+            // Only load response trailers if:
+            // 1. WINHTTP_QUERY_FLAG_TRAILERS is supported by the OS
+            // 2. HTTP/2 or later (WINHTTP_QUERY_FLAG_TRAILERS does not work with HTTP/1.1)
+            // 3. Response trailers not already loaded
+            if (!WinHttpTrailersHelper.OsSupportsTrailers || _responseMessage.Version < WinHttpHandler.HttpVersion20 || _readTrailingHeaders)
+            {
+                return;
+            }
+
+            _readTrailingHeaders = true;
+
+            var bufferLength = WinHttpResponseParser.GetResponseHeaderCharBufferLength(_requestHandle, isTrailingHeaders: true);
+
+            if (bufferLength != 0)
+            {
+                char[] trailersBuffer = ArrayPool<char>.Shared.Rent(bufferLength);
+                try
+                {
+                    WinHttpResponseParser.ParseResponseTrailers(_requestHandle, _responseMessage, trailersBuffer);
+                }
+                finally
+                {
+                    ArrayPool<char>.Shared.Return(trailersBuffer);
+                }
+            }
+        }
+
         public override int Read(byte[] buffer, int offset, int count)
         {
             return ReadAsync(buffer, offset, count, CancellationToken.None).GetAwaiter().GetResult();

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

@@ -0,0 +1,64 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics;
+using System.Net.Http.Headers;
+using System.Runtime.InteropServices;
+using SafeWinHttpHandle = Interop.WinHttp.SafeWinHttpHandle;
+
+namespace System.Net.Http
+{
+    internal static class WinHttpTrailersHelper
+    {
+        // UNITTEST is true when building against WinHttpHandler.Unit.Tests, which includes the source file.
+#if !NETSTANDARD2_1 && !UNITTEST
+        // Trailer property name was chosen to be descriptive and be unlikely to collide with a user set property.
+        // Apps and libraries will use this key so it shouldn't change.
+        private const string RequestMessagePropertyName = "__ResponseTrailers";
+        private class HttpResponseTrailers : HttpHeaders
+        {
+        }
+#endif
+        private static Lazy<bool> s_trailersSupported = new Lazy<bool>(GetTrailersSupported);
+        public static bool OsSupportsTrailers => s_trailersSupported.Value;
+
+        public static HttpHeaders GetResponseTrailers(HttpResponseMessage response)
+        {
+#if NETSTANDARD2_1 || UNITTEST
+            return response.TrailingHeaders;
+#else
+            HttpResponseTrailers responseTrailers = new HttpResponseTrailers();
+            response.RequestMessage.Properties[RequestMessagePropertyName] = responseTrailers;
+            return responseTrailers;
+#endif
+        }
+
+        // There is no way to verify if WINHTTP_QUERY_FLAG_TRAILERS is supported by the OS without creating a request.
+        // Instead, the WinHTTP team recommended to check if WINHTTP_OPTION_STREAM_ERROR_CODE is recognized by the OS.
+        // Both features were introduced in Manganese and are planned to be backported to older Windows versions together.
+        private static bool GetTrailersSupported()
+        {
+            using SafeWinHttpHandle sessionHandle = Interop.WinHttp.WinHttpOpen(
+                    IntPtr.Zero,
+                    Interop.WinHttp.WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
+                    Interop.WinHttp.WINHTTP_NO_PROXY_NAME,
+                    Interop.WinHttp.WINHTTP_NO_PROXY_BYPASS,
+                    (int)Interop.WinHttp.WINHTTP_FLAG_ASYNC);
+
+            if (sessionHandle.IsInvalid) return false;
+            uint buffer = 0;
+            uint bufferSize = sizeof(uint);
+            if (Interop.WinHttp.WinHttpQueryOption(sessionHandle, Interop.WinHttp.WINHTTP_OPTION_STREAM_ERROR_CODE, ref buffer, ref bufferSize))
+            {
+                Debug.Fail("Querying WINHTTP_OPTION_STREAM_ERROR_CODE on a session handle should never succeed.");
+                return false;
+            }
+
+            int lastError = Marshal.GetLastWin32Error();
+
+            // New Windows builds are expected to fail with ERROR_WINHTTP_INCORRECT_HANDLE_TYPE,
+            // when querying WINHTTP_OPTION_STREAM_ERROR_CODE on a session handle.
+            return lastError != Interop.WinHttp.ERROR_INVALID_PARAMETER;
+        }
+    }
+}

src/libraries/System.Net.Http.WinHttpHandler/tests/FunctionalTests/System.Net.Http.WinHttpHandler.Functional.Tests.csproj

@@ -14,11 +14,11 @@
     <Compile Include="BaseCertificateTest.cs" />
     <Compile Include="ServerCertificateTest.cs" />
     <Compile Include="WinHttpHandlerTest.cs" />
-    <Compile Include="XunitTestAssemblyAtrributes.cs" /> 
+    <Compile Include="XunitTestAssemblyAtrributes.cs" />
     <Compile Include="$(CommonPath)\System\Net\Http\HttpHandlerDefaults.cs"
              Link="Common\System\Net\Http\HttpHandlerDefaults.cs" />
     <Compile Include="$(CommonTestPath)System\IO\DelegateStream.cs"
-             Link="Common\System\IO\DelegateStream.cs" />    
+             Link="Common\System\IO\DelegateStream.cs" />
     <Compile Include="$(CommonTestPath)System\Net\Configuration.Certificates.cs"
              Link="Common\System\Net\Configuration.Certificates.cs" />
     <Compile Include="$(CommonTestPath)System\Net\Configuration.Security.cs"
@@ -128,7 +128,7 @@
     <Compile Include="$(CommonTestPath)System\Net\Http\RepeatedFlushContent.cs"
              Link="Common\System\Net\Http\RepeatedFlushContent.cs" />
     <Compile Include="$(CommonTestPath)System\Net\Http\ResponseStreamTest.cs"
-             Link="Common\System\Net\Http\ResponseStreamTest.cs" />    
+             Link="Common\System\Net\Http\ResponseStreamTest.cs" />
     <Compile Include="$(CommonTestPath)System\Net\Http\SchSendAuxRecordHttpTest.cs"
              Link="Common\System\Net\Http\SchSendAuxRecordHttpTest.cs" />
     <Compile Include="$(CommonTestPath)System\Net\Http\SyncBlockingContent.cs"
@@ -143,6 +143,7 @@
     <Compile Include="WinHttpClientHandler.cs" />
     <Compile Include="PlatformHandlerTest.cs" />
     <Compile Include="ClientCertificateTest.cs" />
+    <Compile Include="TrailingHeadersTest.cs" />
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Newtonsoft.Json" Version="$(NewtonsoftJsonVersion)" />