[patch v2] send.2: Add MSG_FASTOPEN flag
From: Wei Wang <hidden>
Date: 2021-09-17 04:16:16
Also in:
netdev
Subsystem:
the rest · Maintainer:
Linus Torvalds
MSG_FASTOPEN flag is available since Linux 3.7. Add detailed description in the manpage according to RFC7413. Signed-off-by: Wei Wang <redacted> Reviewed-by: Yuchung Cheng <redacted> Reviewed-by: Eric Dumazet <edumazet@google.com> --- 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
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2.33.0.464.g1972c5931b-goog