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Re: [Fwd: I-D ACTION:draft-decroy-http-progress-00.txt]

From: Jamie Lokier <jamie@shareable.org>
Date: Tue, 13 Feb 2007 15:21:58 +0000
To: Adrien de Croy <adrien@qbik.com>
Cc: Henrik Nordstrom <henrik@henriknordstrom.net>, ietf-http-wg@w3.org
Message-ID: <20070213152158.GA31785@mail.shareable.org>

Adrien de Croy wrote:
> I am thinking more about your point about using TCP flow control.
> We are able to send a 0 window size, but that won't guarantee that
> the client won't enter into the state where it thinks it is sending
> the body (and would therefore terminate on any 4xx response).

It's not permitted to reduce the TCP advertised window, so you can't
send a 0 window size after you've already opened the window to receive
the request headers of unknown size.

RFC 1122, section

    "A TCP receiver SHOULD NOT shrink the window"

    "Many TCP implementations become confused if the window shrinks
    from the right after data has been sent into a larger window.
    Note that TCP has a heuristic to select the latest window update
    despite possible datagram reordering; as a result, it may ignore a
    window update with a smaller window than previously offered if
    neither the sequence number nor the acknowledgment number is

-- Jamie
Received on Tuesday, 13 February 2007 15:22:18 UTC

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