PR feedback

Author: JamesNK

src/Servers/Kestrel/Core/src/Internal/Http3/Http3FrameWriter.cs

@@ -62,7 +62,10 @@ public Http3FrameWriter(PipeWriter output, ConnectionContext connectionContext,
             _headerEncodingBuffer = new byte[_maxFrameSize];
             _qpackEncoder = new QPackEncoder();
 
-            // TODO(JamesNK): QPack encoder doesn't react to settings change during a stream
+            // Note that QPack encoder doesn't react to settings change during a stream.
+            // Unlikely to be a problem in practice:
+            // - Settings rarely change after the start of a connection.
+            // - Response header size limits are a best-effort requirement in the spec.
             _qpackEncoder.MaxTotalHeaderSize = clientPeerSettings.MaxRequestHeaderFieldSectionSize > int.MaxValue
                 ? int.MaxValue
                 : (int)clientPeerSettings.MaxRequestHeaderFieldSectionSize;

src/Servers/Kestrel/test/InMemory.FunctionalTests/Http3/Http3StreamTests.cs

@@ -2451,7 +2451,7 @@ await requestStream.SendHeadersAsync(new[]
                 new KeyValuePair<string, string>(HeaderNames.Authority, "localhost:80"),
             }, endStream: true);
 
-            await requestStream.WaitForStreamErrorAsync(Http3ErrorCode.InternalError, "Total header size exceeds the maximum size allowed by peer.");
+            await requestStream.WaitForStreamErrorAsync(Http3ErrorCode.InternalError, "The encoded HTTP headers length exceeds the limit specified by the peer of 100 bytes.");
         }
     }
 }

src/Shared/runtime/Http3/QPack/QPackEncoder.cs

@@ -469,10 +469,11 @@ private bool Encode(Span<byte> buffer, bool throwIfNoneEncoded, out int length)
                     return false;
                 }
 
+                // https://quicwg.org/base-drafts/draft-ietf-quic-http.html#section-4.1.1.3
                 _currentTotalHeaderSize += HeaderField.GetLength(key.Length, value.Length);
                 if (_currentTotalHeaderSize > MaxTotalHeaderSize)
                 {
-                    throw new QPackEncodingException("Total header size exceeds the maximum size allowed by peer.");
+                    throw new QPackEncodingException($"The encoded HTTP headers length exceeds the limit specified by the peer of {MaxTotalHeaderSize} bytes.");
                 }
 
                 length += headerLength;