[OpenWrt-Devel] [PATCH] use NTP server received via DHCP

[amine ahd]

The current state of NTP is to load the list of NTP servers
from the static file /etc/config/system.
This patch allows ntpd to get NTP servers from DHCP.


Changes from V1:
	-Users could choose not to use DHCP by setting "use_dhcp" to 0 in /etc/config/system under the ntp section.
	-Users could specify which interfaces to use to get NTP servers from.
	-Sysntpd will exit if no servers are specified in the static list and the DHCP option is disabled.
	-Sysntpd will restart only if all of the following conditions are met:
		*The user allowed DHCP to be used for NTP.
		*The iface action is UP.
		*The iface is specified in the list.
		*The protocol in use is either DHCP or DHCPv6.
	-Code improvements.

Signed-off-by: amine hamed <amine.ahd at gmail.com>
---
 package/utils/busybox/Makefile              |  3 ++
 package/utils/busybox/files/sysntpd         | 31 +++++++++++++++--
 package/utils/busybox/files/sysntpd.hotplug | 54 +++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+), 3 deletions(-)
 create mode 100644 package/utils/busybox/files/sysntpd.hotplug

diff --git a/package/utils/busybox/Makefile b/package/utils/busybox/Makefile
index 5ca4363..3066a85 100644
--- a/package/utils/busybox/Makefile
+++ b/package/utils/busybox/Makefile
@@ -111,6 +111,9 @@ define Package/busybox/install
 	$(CP) $(PKG_INSTALL_DIR)/* $(1)/
 	$(INSTALL_BIN) ./files/cron $(1)/etc/init.d/cron
 	$(INSTALL_BIN) ./files/sysntpd $(1)/etc/init.d/sysntpd
+	$(INSTALL_DIR) $(1)/etc/hotplug.d
+	$(INSTALL_DIR) $(1)/etc/hotplug.d/iface
+	$(INSTALL_BIN) ./files/sysntpd.hotplug $(1)/etc/hotplug.d/iface/30-sysntpd
 	$(INSTALL_BIN) ./files/ntpd-hotplug $(1)/usr/sbin/ntpd-hotplug
 	-rm -rf $(1)/lib64
 endef
diff --git a/package/utils/busybox/files/sysntpd b/package/utils/busybox/files/sysntpd
index f73bb83..c5dac8b 100755
--- a/package/utils/busybox/files/sysntpd
+++ b/package/utils/busybox/files/sysntpd
@@ -1,6 +1,9 @@
 #!/bin/sh /etc/rc.common
 # Copyright (C) 2011 OpenWrt.org
 
+. /lib/functions.sh
+. /usr/share/libubox/jshn.sh
+
 START=98
 
 USE_PROCD=1
@@ -13,21 +16,43 @@ validate_ntp_section() {
 }
 
 start_service() {
-	local server enabled enable_server peer
+	local server enabled enable_server peer ntpservers iface status ntpserver dump
+	local dhcp_ifaces="$(uci -q get system.ntp.dhcp_ifaces)"
 
+	config_load system
+	config_get_bool "use_dhcp" "ntp" "use_dhcp"
 	validate_ntp_section ntp || {
 		echo "validation failed"
 		return 1
 	}
 
 	[ $enabled = 0 ] && return
-
-	[ -z "$server" ] && return
+	[ -z "$server" ] && [ "$use_dhcp" = 0 ] && return
 
 	procd_open_instance
 	procd_set_param command "$PROG" -n
 	[ "$enable_server" = "1" ] && procd_append_param command -l
 	[ -x "$HOTPLUG_SCRIPT" ] && procd_append_param command -S "$HOTPLUG_SCRIPT"
+
+	[ "$use_dhcp" = 1 ] && {
+		if [ -z "$dhcp_ifaces" ]; then
+			dump="$(ubus call network.interface dump)"
+			ntpservers=$(jsonfilter -s "$dump" -e '$["interface"][*]["data"]["ntpserver"]')
+		else
+			for iface in $dhcp_ifaces; do
+				status="$(ubus call network.interface.$iface status)"
+				ntpserver=$(jsonfilter -s "$status" -e '$["data"]["ntpserver"]')
+				[ -n "$ntpserver" ] && \
+					ntpservers="$ntpservers $ntpserver"
+			done
+		fi
+		# add this data so we can use it in the sysntpd hotplug script.
+		procd_set_param data ntp_servers="$ntpservers $server"
+		for ntpserver in $ntpservers; do
+			procd_append_param command -p $ntpserver
+		done
+	}
+
 	for peer in $server; do
 		procd_append_param command -p $peer
 	done
diff --git a/package/utils/busybox/files/sysntpd.hotplug b/package/utils/busybox/files/sysntpd.hotplug
new file mode 100644
index 0000000..34a2f7a
--- /dev/null
+++ b/package/utils/busybox/files/sysntpd.hotplug
@@ -0,0 +1,54 @@
+#!/bin/sh
+
+. /lib/functions.sh
+. /usr/share/libubox/jshn.sh
+
+is_valid_interface() {
+	local list="$(uci get system.ntp.dhcp_ifaces)"
+	[ -z "$list" ] && return 0
+
+	case " $list " in
+		*" $INTERFACE "*)
+			return 0
+		;;
+		*)
+			return 1
+		;;
+	esac
+}
+
+config_load system
+local proto="$(uci get network.$INTERFACE.proto)"
+config_get_bool "use_dhcp" "ntp" "use_dhcp"
+[ "$use_dhcp" = 1 ] && [ "$ACTION" = ifup ] && is_valid_interface && [ "$proto" = dhcp -o "$proto" = dhcp6 ] || exit 0
+
+handle_default_ntp_servers() {
+	local server="$1"
+	new_ntp_servers="$new_ntp_servers $server"
+}
+
+local dhcp_ntp_servers iface status ntpserver dump
+local dhcp_ifaces="$(uci -q get system.ntp.dhcp_ifaces)"
+if [ -z "$dhcp_ifaces" ]; then
+	dump="$(ubus call network.interface dump)"
+	dhcp_ntp_servers=$(jsonfilter -s "$dump" -e '$["interface"][*]["data"]["ntpserver"]')
+else
+	for iface in $dhcp_ifaces; do
+		status="$(ubus call network.interface.$iface status)"
+		ntpserver=$(jsonfilter -s "$status" -e '$["data"]["ntpserver"]')
+		[ -n "$ntpserver" ] && \
+			dhcp_ntp_servers="$dhcp_ntp_servers $ntpserver"
+	done
+fi
+
+new_ntp_servers="$dhcp_ntp_servers"
+#get the default list of ntp servers from the config file and append it to the new list
+config_list_foreach "ntp" "server" handle_default_ntp_servers
+
+#get the current list of ntp servers in the running instance
+local current_ntp_servers=$(ubus call service list '{"name":"sysntpd", "verbose":true}' | jsonfilter -e '$["sysntpd"]["instances"][*]["data"]["ntp_servers"]')
+#if its an up action, the iface uses DHCP and the new list of ntp servers is different from the old, restart sysntpd
+[ "$current_ntp_servers" != "$new_ntp_servers" ] || exit 0
+
+logger -t sysntpd "Reloading sysntpd due to $ACTION of interface $INTERFACE and a change of NTP servers"
+/etc/init.d/sysntpd enabled && /etc/init.d/sysntpd reload
\ No newline at end of file
-- 
2.5.0
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