4.5. Buffering Incoming Streams and Datagrams
In WebTransport over HTTP/3, the client MAY send its SETTINGS frame,
as well as multiple WebTransport CONNECT requests, WebTransport data
streams and WebTransport datagrams, all within a single flight. As
those can arrive out of order, a WebTransport server could be put
into a situation where it receives a stream or a datagram without a
corresponding session. Similarly, a client may receive a server-
initiated stream or a datagram before receiving the CONNECT response
headers from the server.
To handle this case, WebTransport endpoints SHOULD buffer streams and
datagrams until those can be associated with an established session.
To avoid resource exhaustion, the endpoints MUST limit the number of
buffered streams and datagrams. When the number of buffered streams
is exceeded, a stream SHALL be closed by sending a RESET_STREAM and/
or STOP_SENDING with the WEBTRANSPORT_BUFFERED_STREAM_REJECTED error
code. When the number of buffered datagrams is exceeded, a datagram
SHALL be dropped. It is up to an implementation to choose what
stream or datagram to discard.
