[systemd-devel] [PATCH] socket: add support for TCP fast Open
Dave Reisner
d at falconindy.com
Thu Aug 14 06:54:04 PDT 2014
On Thu, Aug 14, 2014 at 02:31:47PM +0530, Susant Sahani wrote:
> TCP Fast Open (TFO) speeds up the opening of successiveTCP)
> 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.
> ---
Why does this default to false? The kernel enables this by default as of
3.13 and exposes /proc/sys/net/ipv4/tcp_fastopen. Are there really
cases where one might want this conditionally enabled/disabled?
> 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 352825f..170d010 100644
> --- a/man/systemd.socket.xml
> +++ b/man/systemd.socket.xml
> @@ -499,6 +499,21 @@
> </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 ad135a1..71c0115 100644
> --- a/src/core/dbus-socket.c
> +++ b/src/core/dbus-socket.c
> @@ -97,6 +97,7 @@ const sd_bus_vtable bus_socket_vtable[] = {
> SD_BUS_PROPERTY("DirectoryMode", "u", bus_property_get_mode, offsetof(Socket, directory_mode), SD_BUS_VTABLE_PROPERTY_CONST),
> SD_BUS_PROPERTY("Accept", "b", bus_property_get_bool, offsetof(Socket, accept), SD_BUS_VTABLE_PROPERTY_CONST),
> SD_BUS_PROPERTY("KeepAlive", "b", bus_property_get_bool, offsetof(Socket, keep_alive), 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 f4acdda..08d0593 100644
> --- a/src/core/load-fragment-gperf.gperf.m4
> +++ b/src/core/load-fragment-gperf.gperf.m4
> @@ -232,6 +232,7 @@ Socket.Accept, config_parse_bool, 0,
> Socket.MaxConnections, config_parse_unsigned, 0, offsetof(Socket, max_connections)
> Socket.KeepAlive, config_parse_bool, 0, offsetof(Socket, keep_alive)
> Socket.NoDelay, config_parse_bool, 0, offsetof(Socket, no_delay)
> +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 5af1596..44827ad 100644
> --- a/src/core/socket.c
> +++ b/src/core/socket.c
> @@ -481,6 +481,7 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
> "%sDirectoryMode: %04o\n"
> "%sKeepAlive: %s\n"
> "%sNoDelay: %s\n"
> + "%sFastOpen: %s\n"
> "%sFreeBind: %s\n"
> "%sTransparent: %s\n"
> "%sBroadcast: %s\n"
> @@ -496,6 +497,7 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
> prefix, s->directory_mode,
> prefix, yes_no(s->keep_alive),
> prefix, yes_no(s->no_delay),
> + prefix, yes_no(s->fast_open),
> prefix, yes_no(s->free_bind),
> prefix, yes_no(s->transparent),
> prefix, yes_no(s->broadcast),
> @@ -798,6 +800,12 @@ static void socket_apply_socket_options(Socket *s, int fd) {
> log_warning_unit(UNIT(s)->id, "TCP_NODELAY 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 98396e7..6c0084c 100644
> --- a/src/core/socket.h
> +++ b/src/core/socket.h
> @@ -135,6 +135,7 @@ struct Socket {
> /* Socket options */
> bool keep_alive;
> bool no_delay;
> + bool fast_open;
> bool free_bind;
> bool transparent;
> bool broadcast;
> --
> 1.9.3
>
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