chrony: improve hotplug and init scripts

- fix the init script to read the right config
- rework the init script to allow reusing its code in the hotplug script
- find wan interfaces in the hotplug script instead of using hardcoded
  name and set the online/offline status separately for IPv4/IPv6
- allow NTP access on interfaces that are configured after chronyd start
- add NTP servers obtained from DHCP, options are specified in a new
  dhcp_ntp_server config section
- start chronyd before the network service, include a patch to always
  have IP_FREEBIND defined, which seems to be missing with uclibc

Signed-off-by: Miroslav Lichvar <mlichvar0@gmail.com>

net/chrony/files/chrony.hotplug

@@ -1,6 +1,44 @@
-COMMAND=/usr/bin/chronyc
+#!/bin/sh
+# Set chronyd online/offline status, allow NTP access and add servers from DHCP
 
-[ -x $COMMAND ] || exit 0
+[ "$ACTION" = ifup -o "$ACTION" = ifdown ] || exit 0
 
-[ "$ACTION" = "ifup" -a "$INTERFACE" = "wan" ] && $COMMAND online
-[ "$ACTION" = "ifdown" -a "$INTERFACE" = "wan" ] && $COMMAND offline
+run_command() {
+	/usr/bin/chronyc -n "$*" > /dev/null 2>&1
+}
+
+run_command tracking || exit 0
+
+. /lib/functions/network.sh
+
+network_find_wan iface4
+network_find_wan6 iface6
+run_command $([ -n "$iface4" ] && echo online || echo offline) 0.0.0.0/0.0.0.0
+run_command $([ -n "$iface6" ] && echo online || echo offline) ::/0
+
+[ "$ACTION" = ifup ] || exit 0
+
+. /lib/functions.sh
+. /etc/init.d/chronyd
+
+config_load chrony
+
+config_foreach handle_allow allow | while read command; do
+	run_command "$command"
+done
+
+# Add servers from DHCP only if the config has a dhcp_ntp_server section
+[ -z "$(config_foreach echo dhcp_ntp_server)" ] && exit 0
+
+. /usr/share/libubox/jshn.sh
+
+for iface in $iface4 $iface6; do
+	json_load "$(ifstatus $iface)"
+	json_select data
+	json_get_var dhcp_ntp_servers ntpserver
+
+	for server in $dhcp_ntp_servers; do
+		run_command add $(NTP_SOURCE_HOSTNAME=$server config_foreach \
+				handle_source dhcp_ntp_server server)
+	done
+done