Hi Wei, On 9/17/21 6:16 AM, Wei Wang wrote:
MSG_FASTOPEN flag is available since Linux 3.7. Add detailed description in the manpage according to RFC7413. Signed-off-by: Wei Wang <weiwan@xxxxxxxxxx> Reviewed-by: Yuchung Cheng <ycheng@xxxxxxxxxx> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Patch applied! Thanks (and to the reviewers too!), Alex
--- Change in v2: corrected some format issues man2/send.2 | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/man2/send.2 b/man2/send.2 index fd28fed90..acaa05be9 100644 --- a/man2/send.2 +++ b/man2/send.2 @@ -252,6 +252,38 @@ data on sockets that support this notion (e.g., of type the underlying protocol must also support .I out-of-band data. +.TP +.BR MSG_FASTOPEN " (since Linux 3.7)" +Attempts TCP Fast Open (RFC7413) and sends data in the SYN like a +combination of +.BR connect (2) +and +.BR write (2), +by performing an implicit +.BR connect (2) +operation. +It blocks until the data is buffered and the handshake has completed. +For a non-blocking socket, +it returns the number of bytes buffered and sent in the SYN packet. +If the cookie is not available locally, +it returns +.BR EINPROGRESS , +and sends a SYN with a Fast Open cookie request automatically. +The caller needs to write the data again when the socket is connected. +On errors, +it sets the same +.I errno +as +.BR connect (2) +if the handshake fails. +This flag requires enabling TCP Fast Open client support on sysctl +.IR net.ipv4.tcp_fastopen . +.IP +Refer to +.B TCP_FASTOPEN_CONNECT +socket option in +.BR tcp (7) +for an alternative approach. .SS sendmsg() The definition of the .I msghdr
-- Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/
