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On 10/07/2020 17:06, Joakim Erdfelt wrote:
> On Fri, Jul 10, 2020 at 10:38 AM Mark Thomas <markt@xxxxxxxxxx
> <mailto:markt@xxxxxxxxxx>> wrote:
<snip/>
> Give the following from RFC 6455:
>
> - 6.1 The session must be OPEN to send a message
> - 7.1.3 Upon either sending or receiving a Close control frame, it is
> said that The WebSocket Closing Handshake is Started and that
> the WebSocket connection is in the CLOSING state.
>
> I do not believe it is legal for an endpoint that has received (and
> processed) a CLOSE from to attempt to send a DATA frame.
>
>
> If you _receive_ a CLOSE frame that starts the close handshake, you can
> still send more frames and even start more messages until your side
> sends it's CLOSE frame.
>
> This is the half-open scenario.
But that is not what RFC 6455 says. 7.1.3 specifically states sending or
*receiving* a close control frame moves the WebSocket connection state
to CLOSING and 6.1 requires the connection state to be OPEN in order to
send a message.
The phrase "half-open" does not appear anywhere I could find in RFC 6455.
What am I missing in RFC 6455 that allows / supports the concept of a
half-closed connection?
The moving from OPEN to CLOSING is a protocol behavior that your implementation should do when it's appropriate.
But your API and Implementation can choose when to do that.
Yeah, this is all interpretation.
The [hybi] list has a long history of discussing this, even from the earliest drafts in 2009.
Jetty moves from OPEN to CLOSING after @OnOpen is called and returns.
And moves from CLOSING to CLOSED once the closing handshake is complete.
When not in OPEN state, attempts to write fail.
The WebSocket Proxy scenario shows this to be the most flexible choice and still within the confines of protocol spec.
I believe there's tests for this in the autobahn websocket testsuite. (but i could be remembering incorrectly).
- Joakim
