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>
---
man2/send.2 | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/man2/send.2 b/man2/send.2
index fd28fed90..a40ae6214 100644
--- a/man2/send.2
+++ b/man2/send.2
@@ -252,6 +252,33 @@ 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
+.B 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 returns the same errno as
+.BR connect (2)
+if the handshake fails. This flag requires enabling TCP Fast Open
+client support on sysctl net.ipv4.tcp_fastopen.
+
+Refer to
+.B TCP_FASTOPEN_CONNECT
+socket option in
+.BR tcp (7)
+for an alternative approach.
.SS sendmsg()
The definition of the
.I msghdr
--
2.33.0.309.g3052b89438-goog
Hello, Wei!
On 9/15/21 7:37 PM, Wei Wang wrote:
quoted hunk
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>
---
man2/send.2 | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/man2/send.2 b/man2/send.2
index fd28fed90..a40ae6214 100644
--- a/man2/send.2
+++ b/man2/send.2
@@ -252,6 +252,33 @@ 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)
You should merge the comma with the above, to avoid an unwanted space:
.BR write (2),
+, by performing an implicit
+.BR connect (2)
+operation. It blocks until the data is buffered and the handshake
Please use semantic newlines. See man-pages(7):
Use semantic newlines
In the source of a manual page, new sentences should be
started on new lines, and long sentences should be split
into lines at clause breaks (commas, semicolons, colons,
and so on). This convention, sometimes known as "semantic
newlines", makes it easier to see the effect of patches,
which often operate at the level of individual sentences or
sentence clauses.
This is especially important after a period, since groff(1) will usually
put 2 spaces after it, but if you hardcode it like above, it will only
print 1 space.
+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
+.B EINPROGRESS
.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 returns the same errno as
errno should be highlighted:
.I errno
Also, errno is set, not returned (as far as user space is concerned); so
something along the lines of "errno is set by connect(2)" or "it can
fail for the same reasons that connect(2) can". Michael probably knows
if there's a typical wording for this in the current manual pages, to
add some consistency.
BTW, should anything be added to the ERRORS section?
+.BR connect (2) > +if the handshake fails. This flag requires enabling TCP Fast Open
+client support on sysctl net.ipv4.tcp_fastopen.
net.ipv4.tcp_fastopen should be highlighted:
.IR net.ipv4.tcp_fastopen .
+
Also from man-pages(7):
Formatting conventions (general)
Paragraphs should be separated by suitable markers (usually
either .PP or .IP). Do not separate paragraphs using blank
lines, as this results in poor rendering in some output
formats (such as PostScript and PDF).
Thanks!
Alex
--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/
On Wed, Sep 15, 2021 at 1:14 PM Alejandro Colomar (man-pages)
[off-list ref] wrote:
Hello, Wei!
On 9/15/21 7:37 PM, Wei Wang wrote:
quoted
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>
---
man2/send.2 | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/man2/send.2 b/man2/send.2
index fd28fed90..a40ae6214 100644
--- a/man2/send.2
+++ b/man2/send.2
@@ -252,6 +252,33 @@ 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)
You should merge the comma with the above, to avoid an unwanted space:
.BR write (2),
quoted
+, by performing an implicit
+.BR connect (2)
+operation. It blocks until the data is buffered and the handshake
Please use semantic newlines. See man-pages(7):
Use semantic newlines
In the source of a manual page, new sentences should be
started on new lines, and long sentences should be split
into lines at clause breaks (commas, semicolons, colons,
and so on). This convention, sometimes known as "semantic
newlines", makes it easier to see the effect of patches,
which often operate at the level of individual sentences or
sentence clauses.
This is especially important after a period, since groff(1) will usually
put 2 spaces after it, but if you hardcode it like above, it will only
print 1 space.
quoted
+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
+.B EINPROGRESS
.BR EINPROGRESS ,
quoted
+, 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 returns the same errno as
errno should be highlighted:
.I errno
Also, errno is set, not returned (as far as user space is concerned); so
something along the lines of "errno is set by connect(2)" or "it can
fail for the same reasons that connect(2) can". Michael probably knows
if there's a typical wording for this in the current manual pages, to
add some consistency.
BTW, should anything be added to the ERRORS section?
quoted
+.BR connect (2) > +if the handshake fails. This flag requires enabling TCP Fast Open
+client support on sysctl net.ipv4.tcp_fastopen.
net.ipv4.tcp_fastopen should be highlighted:
.IR net.ipv4.tcp_fastopen .
quoted
+
Also from man-pages(7):
Formatting conventions (general)
Paragraphs should be separated by suitable markers (usually
either .PP or .IP). Do not separate paragraphs using blank
lines, as this results in poor rendering in some output
formats (such as PostScript and PDF).
Thanks!
Alex
Thanks Alex! Will address those and send out v2.
--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/