implement ipv6-ra executor for controlling ipv6 RA setting on a per-NIC basis

Makefile

@@ -48,7 +48,9 @@ IFQUERY_OBJ = ${IFQUERY_SRC:.c=.o}
 IFUPDOWN_SRC = cmd/ifupdown.c
 IFUPDOWN_OBJ = ${IFUPDOWN_SRC:.c=.o}
 
-EXECUTOR_SCRIPTS = dhcp
+EXECUTOR_SCRIPTS = \
+	dhcp \
+	ipv6-ra
 
 CMD_OBJ = ${MULTICALL_OBJ} ${IFQUERY_OBJ} ${IFUPDOWN_OBJ}
 

executor-scripts/ipv6-ra

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+start() {
+	echo 1 > /proc/sys/net/ipv6/conf/$IFACE/accept_ra
+}
+
+stop() {
+	echo 0 > /proc/sys/net/ipv6/conf/$IFACE/accept_ra
+}
+
+[ -z "$VERBOSE" ] || set -x
+
+case "$PHASE" in
+up) start $impl ;;
+down) stop $impl ;;
+*) ;;
+esac