conntrackd: add systemd support

This patch adds basic systemd support.

The feature can be enabled/disabled at configure time:
 ./configure --disable-systemd

Also, at runtime in conntrackd.conf
General {
	Systemd on|off
}

(by default it's enabled both at runtime and at configure time)

* tell systemd about conntrackd readiness:

When conntrackd starts, it will send systemd the data "READY=1".
At the point the data is sent, conntrackd is fully ready to work
(configuration was OK, sockets OK, et all), so other actions depending
on conntrackd can be safely chained in the machine boot process.

* tell systemd about conntrackd shutting down:

If the admin kills conntrackd with `conntrackd -k', the data "STOPPING=1"
will be send to systemd so it learns about the daemon shutting down. Same
for manual signals.

* watchdog support:

The admin can configure systemd to watch the conntrackd daemon and perform
some actions if conntrackd dies: restart it, reboot the machine, etc...

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

4 files changed, 32 insertions, 0 deletions

diff --git a/doc/stats/conntrackd.conf b/doc/stats/conntrackd.conf
index 16d7a80..b1cca07 100644
--- a/doc/stats/conntrackd.conf
+++ b/doc/stats/conntrackd.conf
@@ -3,6 +3,14 @@
 #
 General {
 	#
+	# Enable systemd support. If conntrackd is compiled with the proper
+	# configuration, you can use a systemd service unit of Type=notify
+	# and use conntrackd with systemd watchdog as well.
+	# Default is: on
+	#
+	#Systemd off
+
+	#
 	# Set the nice value of the daemon. This value goes from -20
 	# (most favorable scheduling) to 19 (least favorable). Using a
 	# negative value reduces the chances to lose state-change events.
diff --git a/doc/sync/alarm/conntrackd.conf b/doc/sync/alarm/conntrackd.conf
index 0223745..39deb47 100644
--- a/doc/sync/alarm/conntrackd.conf
+++ b/doc/sync/alarm/conntrackd.conf
@@ -218,6 +218,14 @@ Sync {
 #
 General {
 	#
+	# Enable systemd support. If conntrackd is compiled with the proper
+	# configuration, you can use a systemd service unit of Type=notify
+	# and use conntrackd with systemd watchdog as well.
+	# Default is: on
+	#
+	#Systemd off
+
+	#
 	# Set the nice value of the daemon, this value goes from -20
 	# (most favorable scheduling) to 19 (least favorable). Using a
 	# very low value reduces the chances to lose state-change events.
diff --git a/doc/sync/ftfw/conntrackd.conf b/doc/sync/ftfw/conntrackd.conf
index 65e7b77..60d7d97 100644
--- a/doc/sync/ftfw/conntrackd.conf
+++ b/doc/sync/ftfw/conntrackd.conf
@@ -241,6 +241,14 @@ Sync {
 #
 General {
 	#
+	# Enable systemd support. If conntrackd is compiled with the proper
+	# configuration, you can use a systemd service unit of Type=notify
+	# and use conntrackd with systemd watchdog as well.
+	# Default is: on
+	#
+	#Systemd off
+
+	#
 	# Set the nice value of the daemon, this value goes from -20
 	# (most favorable scheduling) to 19 (least favorable). Using a
 	# very low value reduces the chances to lose state-change events.
diff --git a/doc/sync/notrack/conntrackd.conf b/doc/sync/notrack/conntrackd.conf
index 3d036fb..b9d42ba 100644
--- a/doc/sync/notrack/conntrackd.conf
+++ b/doc/sync/notrack/conntrackd.conf
@@ -280,6 +280,14 @@ Sync {
 #
 General {
 	#
+	# Enable systemd support. If conntrackd is compiled with the proper
+	# configuration, you can use a systemd service unit of Type=notify
+	# and use conntrackd with systemd watchdog as well.
+	# Default is: on
+	#
+	#Systemd off
+
+	#
 	# Set the nice value of the daemon, this value goes from -20
 	# (most favorable scheduling) to 19 (least favorable). Using a
 	# very low value reduces the chances to lose state-change events.