netdev - Re: [PATCH v3 5/7] net-tcp: Fast Open client

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Date:	Thu, 19 Jul 2012 19:59:16 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Yuchung Cheng <ycheng@...gle.com>
Cc:	davem@...emloft.net, hkchu@...gle.com, edumazet@...gle.com,
	ncardwell@...gle.com, sivasankar@...ucsd.edu,
	netdev@...r.kernel.org
Subject: Re: [PATCH v3 5/7] net-tcp: Fast Open client -
 sendmsg(MSG_FASTOPEN)

On Thu, 2012-07-19 at 09:43 -0700, Yuchung Cheng wrote:
> sendmsg() (or sendto()) with MSG_FASTOPEN is a combo of connect(2)
> and write(2). The application should replace connect() with it to
> send data in the opening SYN packet.
> 
> For blocking socket, sendmsg() blocks until all the data are buffered
> locally and the handshake is completed like connect() call. It
> returns similar errno like connect() if the TCP handshake fails.
> 
> For non-blocking socket, it returns the number of bytes queued (and
> transmitted in the SYN-data packet) if cookie is available. If cookie
> is not available, it transmits a data-less SYN packet with Fast Open
> cookie request option and returns -EINPROGRESS like connect().
> 
> Using MSG_FASTOPEN on connecting or connected socket will result in
> simlar errno like repeating connect() calls. Therefore the application
> should only use this flag on new sockets.
> 
> The buffer size of sendmsg() is independent of the MSS of the connection.
> 
> Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
> ---

Acked-by: Eric Dumazet <edumazet@...gle.com>


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