[LEDE-DEV] [PATCH v2] busybox: sysntpd - Support for NTP servers received via DHCP(v6)

[Hans Dedecker]

The busybox ntpd utility currently uses ntp servers specified in uci.
This patch allows the ntpd utility to use NTP servers received via DHCP(v6)
Following uci parameters have been added:
    use_dhcp : enables NTP server config via DHCP(v6)
    dhcp_interface : use NTP servers received only on the specified DHCP(v6) interfaces; if empty all interfaces are considered

Signed-off-by: Hans Dedecker <dedeckeh at gmail.com>
---

v1 -> v2:
	Make jsonfilter dependant on BUSYBOX_CONFIG_NTPD
	Pipe output of network dump into jsonfilter
	use_dhcp is by default enabled
	Install fine grained procd interface triggers if dhcp_interface is configured

 package/utils/busybox/Makefile      |  4 +--
 package/utils/busybox/files/sysntpd | 57 +++++++++++++++++++++++++++++++++----
 2 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/package/utils/busybox/Makefile b/package/utils/busybox/Makefile
index 24c064c..e5b55e0 100644
--- a/package/utils/busybox/Makefile
+++ b/package/utils/busybox/Makefile
@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=busybox
 PKG_VERSION:=1.24.2
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 PKG_FLAGS:=essential
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
@@ -17,7 +17,7 @@ PKG_SOURCE_URL:=http://www.busybox.net/downloads \
 		http://distfiles.gentoo.org/distfiles/
 PKG_MD5SUM:=2eaae519cac1143bcf583636a745381f
 
-PKG_BUILD_DEPENDS:=BUSYBOX_USE_LIBRPC:librpc BUSYBOX_CONFIG_PAM:libpam
+PKG_BUILD_DEPENDS:=BUSYBOX_USE_LIBRPC:librpc BUSYBOX_CONFIG_PAM:libpam +BUSYBOX_CONFIG_NTPD:jsonfilter
 PKG_BUILD_PARALLEL:=1
 PKG_CHECK_FORMAT_SECURITY:=0
 
diff --git a/package/utils/busybox/files/sysntpd b/package/utils/busybox/files/sysntpd
index f73bb83..6d44280 100755
--- a/package/utils/busybox/files/sysntpd
+++ b/package/utils/busybox/files/sysntpd
@@ -7,13 +7,34 @@ USE_PROCD=1
 PROG=/usr/sbin/ntpd
 HOTPLUG_SCRIPT=/usr/sbin/ntpd-hotplug
 
+get_dhcp_ntp_servers() {
+	local interfaces="$1"
+	local filter="*"
+	local interface ntpservers ntpserver
+
+	for interface in $interfaces; do
+		[ "$filter" = "*" ] && filter="@.interface='$interface'" || filter="$filter, at .interface='$interface'"
+	done
+
+	ntpservers=$(ubus call network.interface dump | jsonfilter -e "@.interface[$filter]['data']['ntpserver']")
+
+	for ntpserver in $ntpservers; do
+		local duplicate=0
+		local entry
+		for entry in $server; do
+			[ "$ntpserver" = "$entry" ] && duplicate=1
+		done
+		[ "$duplicate" = 0 ] && server="$server $ntpserver"
+	done
+}
+
 validate_ntp_section() {
 	uci_validate_section system timeserver "${1}" \
-		'server:list(host)' 'enabled:bool:1' 'enable_server:bool:0'
+		'server:list(host)' 'enabled:bool:1' 'enable_server:bool:0' 'use_dhcp:bool:1' 'dhcp_interface:list(string)'
 }
 
 start_service() {
-	local server enabled enable_server peer
+	local server enabled enable_server use_dhcp dhcp_interface peer
 
 	validate_ntp_section ntp || {
 		echo "validation failed"
@@ -22,6 +43,8 @@ start_service() {
 
 	[ $enabled = 0 ] && return
 
+	[ $use_dhcp = 1 ] && get_dhcp_ntp_servers "$dhcp_interface"
+
 	[ -z "$server" ] && return
 
 	procd_open_instance
@@ -35,8 +58,32 @@ start_service() {
 	procd_close_instance
 }
 
-service_triggers()
-{
-	procd_add_reload_trigger "system"
+service_triggers() {
+	local script name use_dhcp
+
+	script=$(readlink -f "$initscript")
+	name=$(basename ${script:-$initscript})
+
+	procd_open_trigger
+	procd_add_config_trigger "config.change" "system" /etc/init.d/$name reload
+
+	config_load system
+	config_get use_dhcp ntp use_dhcp 1
+
+	[ $use_dhcp = 1 ] && {
+		local dhcp_interface
+		config_get dhcp_interface ntp dhcp_interface
+
+		if [ -n "$dhcp_interface" ]; then
+			for n in $dhcp_interface; do
+				procd_add_interface_trigger "interface.*" $n /etc/init.d/$name reload
+			done
+		else
+			procd_add_raw_trigger "interface.*" 1000 /etc/init.d/$name reload
+		fi
+	}
+
+	procd_close_trigger
+
 	procd_add_validation validate_ntp_section
 }
-- 
1.9.1