HTTP/2: Ignore additional RST_STREAM frames sent to stream (#32449)

Author: JamesNK

src/Servers/Kestrel/Core/src/Internal/Http2/Http2Connection.cs

@@ -717,8 +717,13 @@ private Task ProcessRstStreamFrameAsync()
                 // Second reset
                 if (stream.RstStreamReceived)
                 {
-                    // Hard abort, do not allow any more frames on this stream.
-                    throw new Http2ConnectionErrorException(CoreStrings.FormatHttp2ErrorStreamAborted(_incomingFrame.Type, stream.StreamId), Http2ErrorCode.STREAM_CLOSED);
+                    // https://tools.ietf.org/html/rfc7540#section-5.1
+                    // If RST_STREAM has already been received then the stream is in a closed state.
+                    // Additional frames (other than PRIORITY) are a stream error.
+                    // The server will usually send a RST_STREAM for a stream error, but RST_STREAM
+                    // shouldn't be sent in response to RST_STREAM to avoid a loop. 
+                    // The best course of action here is to do nothing.
+                    return Task.CompletedTask;
                 }
 
                 // No additional inbound header or data frames are allowed for this stream after receiving a reset.

src/Servers/Kestrel/test/InMemory.FunctionalTests/Http2/Http2ConnectionTests.cs

@@ -3067,7 +3067,7 @@ await WaitForConnectionErrorAsync<Http2ConnectionErrorException>(ignoreNonGoAway
         }
 
         [Fact]
-        public async Task RST_STREAM_IncompleteRequest_AdditionalResetFrame_ConnectionAborted()
+        public async Task RST_STREAM_IncompleteRequest_AdditionalResetFrame_IgnoreAdditionalReset()
         {
             var tcs = new TaskCompletionSource<int>(TaskCreationOptions.RunContinuationsAsynchronously);
 
@@ -3085,8 +3085,7 @@ public async Task RST_STREAM_IncompleteRequest_AdditionalResetFrame_ConnectionAb
             await SendRstStreamAsync(1);
             tcs.TrySetResult(0);
 
-            await WaitForConnectionErrorAsync<Http2ConnectionErrorException>(ignoreNonGoAwayFrames: false, expectedLastStreamId: 1,
-                Http2ErrorCode.STREAM_CLOSED, CoreStrings.FormatHttp2ErrorStreamAborted(Http2FrameType.RST_STREAM, 1));
+            await StopConnectionAsync(expectedLastStreamId: 1, ignoreNonGoAwayFrames: false);
         }
 
         [Fact]