Hi Wei,
On 11/5/21 18:19, Wei Wang wrote:
On Fri, Oct 15, 2021 at 3:12 PM Alejandro Colomar (man-pages)
<alx.manpages@xxxxxxxxx> wrote:
Hi Wei,
On 10/15/21 6:08 PM, Wei Wang wrote:
On Fri, Sep 24, 2021 at 4:54 PM Wei Wang <weiwan@xxxxxxxxxx> wrote:
TCP_FASTOPEN socket option was added by:
commit 8336886f786fdacbc19b719c1f7ea91eb70706d4
TCP_FASTOPEN_CONNECT socket option was added by the following patch
series:
commit 065263f40f0972d5f1cd294bb0242bd5aa5f06b2
commit 25776aa943401662617437841b3d3ea4693ee98a
commit 19f6d3f3c8422d65b5e3d2162e30ef07c6e21ea2
commit 3979ad7e82dfe3fb94a51c3915e64ec64afa45c3
Add detailed description for these 2 options.
Also add descriptions for /proc entry tcp_fastopen and tcp_fastopen_key.
Signed-off-by: Wei Wang <weiwan@xxxxxxxxxx>
Sorry for the delay.
I have applied it now.
I also applied some minor changes on top of your patch
(see below).
Thanks!
Alex
---
tcp.7: Minor tweaks to Wei's patch
- wsfix
- Boldface literals (see groff_man(7)).
- Replace '\ ' by \~, per Branden's advise.
- Use phrasal semantic newlines.
- Put '...' in a C comment, to avoid interfering with groff.
It has the side effect that the code example is pure C now.
- Remove incorrect trailing '.IP'.
Cc: Wei Wang <weiwan@xxxxxxxxxx>
Signed-off-by: Alejandro Colomar <alx.manpages@xxxxxxxxx>
diff --git a/man7/tcp.7 b/man7/tcp.7
index 264e3ccc4..69d85c05a 100644
--- a/man7/tcp.7
+++ b/man7/tcp.7
@@ -423,26 +423,31 @@ option.
.\" Since 2.4.0-test7
Enable RFC\ 2883 TCP Duplicate SACK support.
.TP
-.IR tcp_fastopen " (Bitmask; default: 0x1; since Linux 3.7)"
-Enables RFC\ 7413 Fast Open support.
+.IR tcp_fastopen " (Bitmask; default: 0x1; since Linux 3.7)"
+Enables RFC\~7413 Fast Open support.
The flag is used as a bitmap with the following values:
.RS
-.IP 0x1
+.TP
+.B 0x1
Enables client side Fast Open support
-.IP 0x2
+.TP
+.B 0x2
Enables server side Fast Open support
-.IP 0x4
+.TP
+.B 0x4
Allows client side to transmit data in SYN without Fast Open option
-.IP 0x200
+.TP
+.B 0x200
Allows server side to accept SYN data without Fast Open option
-.IP 0x400
+.TP
+.B 0x400
Enables Fast Open on all listeners without
.B TCP_FASTOPEN
socket option
.RE
.TP
.IR tcp_fastopen_key " (since Linux 3.7)"
-Set server side RFC\ 7413 Fast Open key to generate Fast Open cookie
+Set server side RFC\~7413 Fast Open key to generate Fast Open cookie
when server side Fast Open support is enabled.
.TP
.IR tcp_ecn " (Integer; default: see below; since Linux 2.4)"
@@ -1226,19 +1231,19 @@ This option should not be used in code intended
to be
portable.
.TP
.BR TCP_FASTOPEN " (since Linux 3.6)"
-This option enables Fast Open (RFC\ 7413) on the listener socket.
+This option enables Fast Open (RFC\~7413) on the listener socket.
The value specifies the maximum length of pending SYNs
(similar to the backlog argument in
.BR listen (2)).
Once enabled,
-the listener socket grants the TCP Fast Open cookie on incoming
-SYN with TCP Fast Open option.
+the listener socket grants the TCP Fast Open cookie
+on incoming SYN with TCP Fast Open option.
.IP
More importantly it accepts the data in SYN with a valid Fast Open cookie
and responds SYN-ACK acknowledging both the data and the SYN sequence.
.BR accept (2)
-returns a socket that is available for read and write when the handshake
-has not completed yet.
+returns a socket that is available for read and write
+when the handshake has not completed yet.
Thus the data exchange can commence before the handshake completes.
This option requires enabling the server-side support on sysctl
.IR net.ipv4.tcp_fastopen
@@ -1252,18 +1257,18 @@ or
below.
.TP
.BR TCP_FASTOPEN_CONNECT " (since Linux 4.11)"
-This option enables an alternative way to perform Fast Open on the active
-side (client).
+This option enables an alternative way to perform Fast Open
+on the active side (client).
When this option is enabled,
.BR connect (2)
-would behave differently depending on if a Fast Open cookie is available
-for the destination.
+would behave differently depending on
+if a Fast Open cookie is available for the destination.
.IP
If a cookie is not available (i.e. first contact to the destination),
.BR connect (2)
behaves as usual by sending a SYN immediately,
-except the SYN would include an empty Fast Open cookie option to solicit a
-cookie.
+except the SYN would include an empty Fast Open cookie option
+to solicit a cookie.
.IP
If a cookie is available,
.BR connect (2)
@@ -1297,13 +1302,12 @@ without
.BR write (2)
will cause the blocking socket to be blocked forever.
.IP
-The application should either set
+The application should either set
.B TCP_FASTOPEN_CONNECT
socket option before
.BR write (2)
or
-.BR sendmsg (2)
-,
+.BR sendmsg (2),
or call
.BR write (2)
or
@@ -1322,11 +1326,10 @@ setsockopt(s, IPPROTO_TCP, TCP_FASTOPEN_CONNECT,
1, ...);
connect(s);
write(s); // write() should always follow connect() in order to
trigger SYN to go out
read(s)/write(s);
-...
+/* ... */
close(s);
.EE
.in
-.IP
.SS Sockets API
TCP provides limited support for out-of-band data,
in the form of (a single byte of) urgent data.
