add ifupdown integration (#31)

* add ifupdown integration

* fixup! add ifupdown integration

---------

Co-authored-by: satanist <satanist+fsmi@bureaucracy.de>

scripts/clatd.ifupdown

@@ -0,0 +1,49 @@
+#!/bin/sh
+
+# clatd(8) integration in interfaces(5)
+
+# To use just copy this script to /etc/network/if-up.d/ and
+# /etc/network/if-down.d/
+
+# To configure which connection should include clatd the file
+# /etc/default/clatd is used. To enable clatd on a interface
+# include the interface in CLATD_IFACES (space sperated)
+
+# For logical intefaces (i.e. wpa_supplicant integration) you
+# can also set one CLATD_LOGICAL. See interfaces(5) for details.
+
+. /etc/default/clatd
+
+use_clatd=0
+
+for iface in $CLATD_IFACES
+do
+	if [ "$iface" = "$IFACE" ]
+	then
+		use_clatd=1
+		break
+	fi
+done
+
+if [ "$LOGICAL" = "$CLATD_LOGICAL" ]
+then
+	use_clatd=1
+fi
+
+if [ "$use_clatd" -ne 1 ]
+then
+	exit 0
+fi
+
+case "$PHASE" in
+	post-up)
+		systemctl start clatd@"$IFACE"
+		exit 0
+		;;
+	pre-down)
+		systemctl stop clatd@"$IFACE"
+		;;
+	*)
+		exit 0
+		;;
+esac