Increase Http2 Header limit size to the MaxFrameSize

[jkotalik]

Part of #12213

Increased the limit to the default max frame size.

[jkotalik]

I don't believe this address all issues. The Http2Stream still calls ResetAndAbort with a protocol violation here: https://github.com/aspnet/AspNetCore/blob/caa910ceeba5f2b2c02c47a23ead0ca31caea6f0/src/Servers/Kestrel/Core/src/Internal/Http2/Http2Stream.cs#L207. I believe this is the real issue the stress app is hitting.

[halter73]

I agree that ProtocolError seems wrong for going over a server-configured limit that's not configured as part of the protocol. What do we think is better than Http2ErrorCode.PROTOCOL_ERROR though? My feeling is that Http2ErrorCode.INTERNAL is probably best.

[halter73]

Nit: I think it's OK just to use 16,384. People who care whether or not it's a power of two will intuitively know that it is.

[jkotalik]

I think this PR is fine for now, but I'll keep the original issue open to address the request line issues.

[Tratcher]

We should work out how we can send a 4XX response before resetting.

[halter73]

I think if you RST a connection, no response at all is better than a 4XX. That aligns better with an HTTP/1.1 connection reset. We wont be able to write a 4XX anyway if the app has already started writing a response.

[Tratcher]

These are h2 stream resets, not tcp resets. They also happen as the request is received and prevent it from being dispatched to the app. Sending a 4XX would align with how we handle this class of errors in HTTP/1.1.

[halter73]

I think I understand what you're saying. I was thinking of receiving a HTTP/2 stream reset, not a tcp reset, but you're right I lost some of the context. Sending a 4XX for too-large headers is the right thing to do.