[H/3] Fix handling H3_NO_ERROR

src/libraries/Common/tests/System/Net/Http/Http3LoopbackStream.cs

@@ -423,9 +423,9 @@ private async Task DrainResponseData()
             }
         }
 
-        public void Abort(long errorCode)
+        public void Abort(long errorCode, QuicAbortDirection direction = QuicAbortDirection.Both)
         {
-            _stream.Abort(QuicAbortDirection.Both, errorCode);
+            _stream.Abort(direction, errorCode);
         }
 
         public async Task<(long? frameType, byte[] payload)> ReadFrameAsync()

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http3RequestStream.cs

@@ -222,6 +222,10 @@ await Task.WhenAny(sendRequestTask, readResponseTask).ConfigureAwait(false) == s
                     {
                         await writesClosed.WaitAsync(_requestBodyCancellationSource.Token).ConfigureAwait(false);
                     }
+                    catch (QuicException qex) when (qex.QuicError == QuicError.StreamAborted && qex.ApplicationErrorCode == (long)Http3ErrorCode.NoError)
+                    {
+                        // The server doesn't need the whole request to respond so it's aborting its reading side gracefully, see https://datatracker.ietf.org/doc/html/rfc9114#section-4.1-15.
+                    }
                     catch (OperationCanceledException)
                     {
                         // If the request got cancelled before WritesClosed completed, avoid leaking an unobserved task exception.
@@ -475,6 +479,10 @@ private async Task SendContentAsync(HttpContent content, CancellationToken cance
 
                 if (HttpTelemetry.Log.IsEnabled()) HttpTelemetry.Log.RequestContentStop(bytesWritten);
             }
+            catch (HttpRequestException hex) when (hex.InnerException is QuicException qex && qex.QuicError == QuicError.StreamAborted && qex.ApplicationErrorCode == (long)Http3ErrorCode.NoError)
+            {
+                // The server doesn't need the whole request to respond so it's aborting its reading side gracefully, see https://datatracker.ietf.org/doc/html/rfc9114#section-4.1-15.
+            }
             finally
             {
                 _requestSendCompleted = true;

src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http3.cs

@@ -392,7 +392,7 @@ public async Task SendAsync_RequestRejected_ClientRetries()
                 await using (Http3LoopbackConnection connection1 = (Http3LoopbackConnection)await server.EstablishGenericConnectionAsync())
                 {
                     await using Http3LoopbackStream stream = await connection1.AcceptRequestStreamAsync();
-                    stream.Abort(0x10B); // H3_REQUEST_REJECTED
+                    stream.Abort(Http3LoopbackConnection.H3_REQUEST_REJECTED);
                     await stream.DisposeAsync();
                     // shutdown the connection gracefully via GOAWAY frame for good measure
                     await connection1.ShutdownAsync(true);
@@ -423,6 +423,41 @@ public async Task SendAsync_RequestRejected_ClientRetries()
             await new[] { clientTask, serverTask }.WhenAllOrAnyFailed(20_000);
         }
 
+        [Fact]
+        public async Task SendAsync_RequestAbortedNoError_ClientSucceeds()
+        {
+            using Http3LoopbackServer server = CreateHttp3LoopbackServer();
+            string httpContent = "hello world";
+
+            Task serverTask = Task.Run(async () =>
+            {
+                await using (Http3LoopbackConnection connection = (Http3LoopbackConnection)await server.EstablishGenericConnectionAsync())
+                {
+                    await using Http3LoopbackStream stream = await connection.AcceptRequestStreamAsync();
+                    stream.Abort(Http3LoopbackConnection.H3_NO_ERROR, QuicAbortDirection.Read);
+                    await stream.SendResponseAsync(content: httpContent);
+                    await stream.DisposeAsync();
+                }
+            });
+
+            Task clientTask = Task.Run(async () =>
+            {
+                using HttpClient client = CreateHttpClient();
+                using HttpRequestMessage request = new()
+                {
+                    Method = HttpMethod.Post,
+                    RequestUri = server.Address,
+                    Version = HttpVersion30,
+                    VersionPolicy = HttpVersionPolicy.RequestVersionExact,
+                    Content = new ByteAtATimeContent(64*1024)
+                };
+                using var response = await client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
+                var content = await response.Content.ReadAsStringAsync();
+                Assert.Equal(httpContent, content);
+            });
+
+            await new[] { clientTask, serverTask }.WhenAllOrAnyFailed(20_000);
+        }
 
         [Fact]
         public async Task ServerClosesConnection_ResponseContentStream_ThrowsHttpProtocolException()