From bbecf54315f4e8b190cbd63adeea0fb61d7f2f88 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marie=20P=C3=ADchov=C3=A1?=
 <11718369+ManickaP@users.noreply.github.com>
Date: Mon, 11 Mar 2024 09:24:01 +0100
Subject: [PATCH] [Http/2] Fix handling of effectively empty DATA frame
 (#99502)

* Fix handling effectively empty DATA frame

* Added test
---
 .../SocketsHttpHandler/Http2Connection.cs     |  7 ++-
 .../HttpClientHandlerTest.Http2.cs            | 44 +++++++++++++++++++
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Connection.cs b/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Connection.cs
index 4d84e54748e3a..3ffa35fa00fec 100644
--- a/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Connection.cs
+++ b/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Connection.cs
@@ -765,9 +765,12 @@ private void ProcessDataFrame(FrameHeader frameHeader)
             // Just ignore the frame in this case.
 
             ReadOnlySpan<byte> frameData = GetFrameData(_incomingBuffer.ActiveSpan.Slice(0, frameHeader.PayloadLength), hasPad: frameHeader.PaddedFlag, hasPriority: false);
-
             bool endStream = frameHeader.EndStreamFlag;
-            http2Stream?.OnResponseData(frameData, endStream);
+
+            if (frameData.Length > 0 || endStream)
+            {
+                http2Stream?.OnResponseData(frameData, endStream);
+            }
 
             if (frameData.Length > 0)
             {
diff --git a/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http2.cs b/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http2.cs
index 33c94856d270c..3036935ef5533 100644
--- a/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http2.cs
+++ b/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http2.cs
@@ -205,6 +205,50 @@ public async Task Http2_ZeroLengthResponseBody_Success()
             }
         }
 
+        [Fact]
+        public async Task Http2_DataFrameOnlyPadding_Success()
+        {
+            using (Http2LoopbackServer server = Http2LoopbackServer.CreateServer())
+            using (HttpClient client = CreateHttpClient())
+            {
+                Task<HttpResponseMessage> sendTask = client.GetAsync(server.Address, HttpCompletionOption.ResponseHeadersRead);
+
+                Http2LoopbackConnection connection = await server.EstablishConnectionAsync();
+
+                int streamId = await connection.ReadRequestHeaderAsync();
+
+                await connection.SendDefaultResponseHeadersAsync(streamId);
+
+                // Send zero-length DATA frame with padding
+                byte paddingLength = byte.MaxValue;
+                int dataLength = 1024;
+                DataFrame frame = new DataFrame(new byte[0], FrameFlags.Padded, paddingLength, streamId);
+                await connection.WriteFrameAsync(frame);
+
+                HttpResponseMessage response = await sendTask;
+                Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+
+                using var responseStream = response.Content.ReadAsStream();
+
+                // The read must pend because we havent received any data yet.
+                var buffer = new byte[dataLength];
+                var readTask = responseStream.ReadAtLeastAsync(buffer, dataLength);
+                Assert.False(readTask.IsCompleted);
+
+                // Send DATA frame with padding
+                frame = new DataFrame(new byte[dataLength], FrameFlags.Padded, paddingLength, streamId);
+                await connection.WriteFrameAsync(frame);
+
+                Assert.Equal(dataLength, await readTask);
+
+                // Send zero-length, end-stream DATA frame with padding
+                frame = new DataFrame(new byte[0], FrameFlags.Padded | FrameFlags.EndStream, paddingLength, streamId);
+                await connection.WriteFrameAsync(frame);
+
+                Assert.Equal(0, await responseStream.ReadAsync(buffer));
+            }
+        }
+
         [Theory]
         [InlineData("Client content", null)]
         [InlineData("Client content", "Server content")]