WinHttpHandler: Read HTTP/2 trailing headers

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

@@ -69,6 +69,7 @@ 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;

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

@@ -1,7 +1,7 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<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>

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, Interop.WinHttp.WINHTTP_QUERY_RAW_HEADERS_CRLF, 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;
 
@@ -93,7 +93,7 @@ public static HttpResponseMessage CreateResponseMessage(
                 response.RequestMessage = request;
 
                 // Parse raw response headers and place them into response message.
-                ParseResponseHeaders(requestHandle, response, buffer, stripEncodingHeaders);
+                ParseResponseHeaders(requestHandle, Interop.WinHttp.WINHTTP_QUERY_RAW_HEADERS_CRLF, response, buffer, stripEncodingHeaders, isTrailers: false);
 
                 if (response.RequestMessage.Method != HttpMethod.Head)
                 {
@@ -223,7 +223,7 @@ 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, uint infoLevel, bool isTrailingHeaders)
         {
             char* buffer = null;
             int bufferLength = 0;
@@ -233,11 +233,21 @@ private static unsafe int GetResponseHeaderCharBufferLength(SafeWinHttpHandle re
             {
                 int lastError = Marshal.GetLastWin32Error();
 
-                Debug.Assert(lastError != Interop.WinHttp.ERROR_WINHTTP_HEADER_NOT_FOUND);
+                if (!isTrailingHeaders)
+                {
+                    Debug.Assert(lastError != Interop.WinHttp.ERROR_WINHTTP_HEADER_NOT_FOUND);
 
-                if (lastError != Interop.WinHttp.ERROR_INSUFFICIENT_BUFFER)
+                    if (lastError != Interop.WinHttp.ERROR_INSUFFICIENT_BUFFER)
+                    {
+                        throw WinHttpException.CreateExceptionUsingError(lastError, nameof(Interop.WinHttp.WinHttpQueryHeaders));
+                    }
+                }
+                else
                 {
-                    throw WinHttpException.CreateExceptionUsingError(lastError, nameof(Interop.WinHttp.WinHttpQueryHeaders));
+                    if (!(lastError == Interop.WinHttp.ERROR_INSUFFICIENT_BUFFER || lastError == Interop.WinHttp.ERROR_WINHTTP_HEADER_NOT_FOUND))
+                    {
+                        throw WinHttpException.CreateExceptionUsingError(lastError, nameof(Interop.WinHttp.WinHttpQueryHeaders));
+                    }
                 }
             }
 
@@ -286,47 +296,69 @@ private static string GetReasonPhrase(HttpStatusCode statusCode, char[] buffer,
                 new string(buffer, 0, bufferLength);
         }
 
-        private static void ParseResponseHeaders(
+        private class HttpResponseTrailers : HttpHeaders
+        {
+        }
+
+        public static void ParseResponseHeaders(
             SafeWinHttpHandle requestHandle,
+            uint infoLevel,
             HttpResponseMessage response,
             char[] buffer,
-            bool stripEncodingHeaders)
+            bool stripEncodingHeaders,
+            bool isTrailers)
         {
             HttpResponseHeaders responseHeaders = response.Headers;
             HttpContentHeaders contentHeaders = response.Content.Headers;
+#if NETSTANDARD2_1
+            HttpResponseHeaders responseTrailers = response.TrailingHeaders;
+#else
+            HttpResponseTrailers responseTrailers = new HttpResponseTrailers();
+            response.RequestMessage.Properties["__ResponseTrailers"] = responseTrailers;
+#endif
 
             int bufferLength = GetResponseHeader(
                 requestHandle,
-                Interop.WinHttp.WINHTTP_QUERY_RAW_HEADERS_CRLF,
+                infoLevel,
                 buffer);
 
             var reader = new WinHttpResponseHeaderReader(buffer, 0, bufferLength);
 
-            // Skip the first line which contains status code, etc. information that we already parsed.
-            reader.ReadLine();
+            if (!isTrailers)
+            {
+                // Skip the first line which contains status code, etc. information that we already parsed.
+                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))
             {
-                if (!responseHeaders.TryAddWithoutValidation(headerName, headerValue))
+                if (!isTrailers)
                 {
-                    if (stripEncodingHeaders)
+                    if (!responseHeaders.TryAddWithoutValidation(headerName, headerValue))
                     {
-                        // Remove Content-Length and Content-Encoding headers if we are
-                        // decompressing the response stream in the handler (due to
-                        // WINHTTP not supporting it in a particular downlevel platform).
-                        // This matches the behavior of WINHTTP when it does decompression itself.
-                        if (string.Equals(HttpKnownHeaderNames.ContentLength, headerName, StringComparison.OrdinalIgnoreCase) ||
-                            string.Equals(HttpKnownHeaderNames.ContentEncoding, headerName, StringComparison.OrdinalIgnoreCase))
+                        if (stripEncodingHeaders)
                         {
-                            continue;
+                            // Remove Content-Length and Content-Encoding headers if we are
+                            // decompressing the response stream in the handler (due to
+                            // WINHTTP not supporting it in a particular downlevel platform).
+                            // This matches the behavior of WINHTTP when it does decompression itself.
+                            if (string.Equals(HttpKnownHeaderNames.ContentLength, headerName, StringComparison.OrdinalIgnoreCase) ||
+                                string.Equals(HttpKnownHeaderNames.ContentEncoding, headerName, StringComparison.OrdinalIgnoreCase))
+                            {
+                                continue;
+                            }
                         }
-                    }
 
-                    contentHeaders.TryAddWithoutValidation(headerName, headerValue);
+                        contentHeaders.TryAddWithoutValidation(headerName, headerValue);
+                    }
+                }
+                else
+                {
+                    responseTrailers.TryAddWithoutValidation(headerName, headerValue);
                 }
             }
         }

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 +265,37 @@ private async Task<int> ReadAsyncCore(byte[] buffer, int offset, int count, Canc
             }
         }
 
+        private void ReadResponseTrailers()
+        {
+            // Only load response trailers if:
+            // 1. HTTP/2 or later
+            // 2. Response trailers not already loaded
+            if (_readTrailingHeaders || _responseMessage.Version < WinHttpHandler.HttpVersion20)
+            {
+                return;
+            }
+
+            _readTrailingHeaders = true;
+
+            var bufferLength = WinHttpResponseParser.GetResponseHeaderCharBufferLength(
+                _requestHandle,
+                Interop.WinHttp.WINHTTP_QUERY_RAW_HEADERS_CRLF | Interop.WinHttp.WINHTTP_QUERY_FLAG_TRAILERS,
+                isTrailingHeaders: true);
+
+            if (bufferLength != 0)
+            {
+                char[] trailersBuffer = ArrayPool<char>.Shared.Rent(bufferLength);
+                try
+                {
+                    WinHttpResponseParser.ParseResponseHeaders(_requestHandle, Interop.WinHttp.WINHTTP_QUERY_RAW_HEADERS_CRLF | Interop.WinHttp.WINHTTP_QUERY_FLAG_TRAILERS, _responseMessage, trailersBuffer, stripEncodingHeaders: false, isTrailers: true);
+                }
+                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/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"
@@ -126,7 +126,7 @@
     <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"
@@ -141,6 +141,7 @@
     <Compile Include="WinHttpClientHandler.cs" />
     <Compile Include="PlatformHandlerTest.cs" />
     <Compile Include="ClientCertificateTest.cs" />
+    <Compile Include="TrailingHeadersTest.cs" />
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Newtonsoft.Json" Version="$(NewtonsoftJsonVersion)" />