QPACK streams created regardless of max dynamic table size 0

[gmarzot]

ran across this while experimenting with webtransport streams connecting the relay server in the moxygen project.

when connecting to a moxygen/proxygen server via HTTP3 at session start, i am observing the generation of 2 QPACK streams. apparently this occurs regardless of whether a SETTINGS frame has been sent or whether the SETTINGS_QPACK_MAX_TABLE_CAPACITY is set to 0 (the default). in cases where header compression is not needed/expected then these streams don't need to be created.

debug output show the quic stream creation

INFO:__main__:H3 connection initialized INFO:quic:[c33573459ee6dd96] ALPN negotiated protocol h3 INFO:__main__:QUIC EVENT: stream: unknown event: HandshakeCompleted(alpn_protocol='h3', early_data_accepted=False, session_resumed=False) INFO:__main__:Transmitting data DEBUG:quic:[c33573459ee6dd96] Stream 3 created by peer DEBUG:quic:[c33573459ee6dd96] Stream 7 created by peer DEBUG:quic:[c33573459ee6dd96] Stream 11 created by peer INFO:__main__:QUIC EVENT: stream: unknown event: ConnectionIdIssued(connection_id=b'\x01\x0c?\xa65\x84m\x80') INFO:__main__:QUIC EVENT: stream: 3 event: StreamDataReceived(data=b'\x00\x04%\x01P\x00\x06\x80\x02\x00\x00\x07@d\x08\x01\x80\xff\xd2w\x01Bv\x013\x01\xab7B\x01!\xc0\x00\x00\x00\xfa\xce\xb0\x0c', end_stream=False, stream_id=3)
INFO:main:QUIC EVENT: stream: 3 raw data: 0x0004250150000680020000074064080180ffd277014276013301ab6037420121c0000000faceb00c
INFO:main:QUIC EVENT: stream: 7 event: StreamDataReceived(data=b'\x02', end_stream=False, stream_id=7)
INFO:main:QUIC EVENT: stream: 7 raw data: 0x02
INFO:main:QUIC EVENT: stream: 11 event: StreamDataReceived(data=b'\x03', end_stream=False, stream_id=11)
INFO:main:QUIC EVENT: stream: 11 raw data: 0x03

--- rfc9204 ---
3.2. Dynamic Table
4.2. Encoder and Decoder Streams
5. Configuration