[systemd-devel] [PATCH 2/3] socket: Add support for TCP Fast Open

[Lennart Poettering]

On Tue, 29.07.14 23:10, Susant Sahani (susant at redhat.com) wrote:

Looks good. Wanted to apply. But this requires your previous patch, so
please rebase on a new version of that! Thanks!

> TCP Fast Open (TFO) speeds up the opening of successive
> TCP)connections between two endpoints.It works by using a TFO cookie
> in the initial SYN packet to authenticate a previously connected client.
> It starts sending data to the client before the receipt
> of the final ACK packet of the three way handshake is received, skipping
> a round trip and lowering the latency in the start of transmission of
> data.
> ---
>  man/systemd.socket.xml                | 15 +++++++++++++++
>  src/core/dbus-socket.c                |  1 +
>  src/core/load-fragment-gperf.gperf.m4 |  1 +
>  src/core/socket.c                     |  8 ++++++++
>  src/core/socket.h                     |  1 +
>  5 files changed, 26 insertions(+)
> 
> diff --git a/man/systemd.socket.xml b/man/systemd.socket.xml
> index 6dbcc81..e6bbb2e 100644
> --- a/man/systemd.socket.xml
> +++ b/man/systemd.socket.xml
> @@ -524,6 +524,21 @@
>                          </varlistentry>
>  
>                          <varlistentry>
> +                                <term><varname>FastOpen=</varname></term>
> +                                <listitem><para>Takes a boolean
> +                                argument. It works by using a TFO cookie (a TCP option) in the initial
> +                                SYN packet to authenticate a previously connected client. If successful,
> +                                it may start sending data to the client before the receipt of the final
> +                                ACK packet of the three way handshake is received, skipping a round trip
> +                                and lowering the latency in the start of transmission of data.
> +                                This controls the TCP_FASTOPEN socket option (see
> +                                the <ulink url="http://lwn.net/Articles/508865/">TCP
> +                                Fast Open: expediting web services</ulink> for details.)
> +                                Defaults to
> +                                <option>false</option>.</para></listitem>
> +                        </varlistentry>
> +
> +                        <varlistentry>
>                                  <term><varname>Priority=</varname></term>
>                                  <listitem><para>Takes an integer
>                                  argument controlling the priority for
> diff --git a/src/core/dbus-socket.c b/src/core/dbus-socket.c
> index 348afbd..f9ef7ef 100644
> --- a/src/core/dbus-socket.c
> +++ b/src/core/dbus-socket.c
> @@ -100,6 +100,7 @@ const sd_bus_vtable bus_socket_vtable[] = {
>          SD_BUS_PROPERTY("KeepAliveTime", "t", bus_property_get_usec, offsetof(Socket, keep_alive_time), SD_BUS_VTABLE_PROPERTY_CONST),
>          SD_BUS_PROPERTY("KeepAliveInterval", "t", bus_property_get_usec, offsetof(Socket, keep_alive_interval), SD_BUS_VTABLE_PROPERTY_CONST),
>          SD_BUS_PROPERTY("KeepAliveProbes", "i", bus_property_get_int, offsetof(Socket, keep_alive_cnt), SD_BUS_VTABLE_PROPERTY_CONST),
> +        SD_BUS_PROPERTY("FastOpen" , "b", bus_property_get_bool, offsetof(Socket, fast_open), SD_BUS_VTABLE_PROPERTY_CONST),
>          SD_BUS_PROPERTY("Priority", "i", bus_property_get_int, offsetof(Socket, priority), SD_BUS_VTABLE_PROPERTY_CONST),
>          SD_BUS_PROPERTY("ReceiveBuffer", "t", bus_property_get_size, offsetof(Socket, receive_buffer), SD_BUS_VTABLE_PROPERTY_CONST),
>          SD_BUS_PROPERTY("SendBuffer", "t", bus_property_get_size, offsetof(Socket, send_buffer), SD_BUS_VTABLE_PROPERTY_CONST),
> diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
> index af9f9cc..3fea038 100644
> --- a/src/core/load-fragment-gperf.gperf.m4
> +++ b/src/core/load-fragment-gperf.gperf.m4
> @@ -234,6 +234,7 @@ Socket.KeepAlive,                config_parse_bool,                  0,
>  Socket.KeepAliveTime,            config_parse_sec,                   0,                             offsetof(Socket, keep_alive_time)
>  Socket.KeepAliveInterval,        config_parse_sec,                   0,                             offsetof(Socket, keep_alive_interval)
>  Socket.KeepAliveProbes,          config_parse_unsigned,              0,                             offsetof(Socket, keep_alive_cnt)
> +Socket.FastOpen,                 config_parse_bool,                  0,                             offsetof(Socket, fast_open)
>  Socket.Priority,                 config_parse_int,                   0,                             offsetof(Socket, priority)
>  Socket.ReceiveBuffer,            config_parse_iec_size,              0,                             offsetof(Socket, receive_buffer)
>  Socket.SendBuffer,               config_parse_iec_size,              0,                             offsetof(Socket, send_buffer)
> diff --git a/src/core/socket.c b/src/core/socket.c
> index c770fe2..b798d4e 100644
> --- a/src/core/socket.c
> +++ b/src/core/socket.c
> @@ -480,6 +480,7 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
>                  "%sSocketMode: %04o\n"
>                  "%sDirectoryMode: %04o\n"
>                  "%sKeepAlive: %s\n"
> +                "%sFastOpen: %s\n"
>                  "%sFreeBind: %s\n"
>                  "%sTransparent: %s\n"
>                  "%sBroadcast: %s\n"
> @@ -494,6 +495,7 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
>                  prefix, s->socket_mode,
>                  prefix, s->directory_mode,
>                  prefix, yes_no(s->keep_alive),
> +                prefix, yes_no(s->fast_open),
>                  prefix, yes_no(s->free_bind),
>                  prefix, yes_no(s->transparent),
>                  prefix, yes_no(s->broadcast),
> @@ -823,6 +825,12 @@ static void socket_apply_socket_options(Socket *s, int fd) {
>                          log_warning_unit(UNIT(s)->id, "TCP_KEEPCNT failed: %m");
>          }
>  
> +        if (s->fast_open) {
> +                int b = s->fast_open;
> +                if (setsockopt(fd, SOL_TCP, TCP_FASTOPEN, &b, sizeof(b)) < 0)
> +                        log_warning_unit(UNIT(s)->id, "TCP_FASTOPEN failed: %m");
> +        }
> +
>          if (s->broadcast) {
>                  int one = 1;
>                  if (setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &one, sizeof(one)) < 0)
> diff --git a/src/core/socket.h b/src/core/socket.h
> index aa300e5..9cb82fa 100644
> --- a/src/core/socket.h
> +++ b/src/core/socket.h
> @@ -136,6 +136,7 @@ struct Socket {
>  
>          /* Socket options */
>          bool keep_alive;
> +        bool fast_open;
>          bool free_bind;
>          bool transparent;
>          bool broadcast;


Lennart

-- 
Lennart Poettering, Red Hat