fix(timesync): ensure that auto-update waits for time sync (#609)

- Added check to not attempt auto update if time sync is needed and not yet successful (delays 30 second to recheck).
- Added resync of time when DHCP or link state changes if online
- Added conditional* fallback from configured* NTP servers to the IP-named NTP servers, and then to the DNS named ones if that fails
- Added conditional* fallback from the configured* HTTP servers to the default DNS named ones.
- Uses the configuration* option for how many queries to run in parallel
- Added known static IPs for time servers (in case DNS resolution isn't up yet)
- Added time.cloudflare.com to fall-back NTP servers
- Added fallback to NTP via hostnames
- Logs the resultant time (and mode)

network.go

@@ -15,7 +15,7 @@ var (
 	networkState *network.NetworkInterfaceState
 )
 
-func networkStateChanged() {
+func networkStateChanged(isOnline bool) {
 	// do not block the main thread
 	go waitCtrlAndRequestDisplayUpdate(true)
 
@@ -37,6 +37,13 @@ func networkStateChanged() {
 			networkState.GetFQDN(),
 		}, true)
 	}
+
+	// if the network is now online, trigger an NTP sync if still needed
+	if isOnline && timeSync != nil && (isTimeSyncNeeded() || !timeSync.IsSyncSuccess()) {
+		if err := timeSync.Sync(); err != nil {
+			logger.Warn().Str("error", err.Error()).Msg("unable to sync time on network state change")
+		}
+	}
 }
 
 func initNetwork() error {
@@ -48,13 +55,13 @@ func initNetwork() error {
 		NetworkConfig:   config.NetworkConfig,
 		Logger:          networkLogger,
 		OnStateChange: func(state *network.NetworkInterfaceState) {
-			networkStateChanged()
+			networkStateChanged(state.IsOnline())
 		},
 		OnInitialCheck: func(state *network.NetworkInterfaceState) {
-			networkStateChanged()
+			networkStateChanged(state.IsOnline())
 		},
-		OnDhcpLeaseChange: func(lease *udhcpc.Lease) {
-			networkStateChanged()
+		OnDhcpLeaseChange: func(lease *udhcpc.Lease, state *network.NetworkInterfaceState) {
+			networkStateChanged(state.IsOnline())
 
 			if currentSession == nil {
 				return
@@ -64,7 +71,15 @@ func initNetwork() error {
 		},
 		OnConfigChange: func(networkConfig *network.NetworkConfig) {
 			config.NetworkConfig = networkConfig
-			networkStateChanged()
+			networkStateChanged(false)
+
+			if mDNS != nil {
+				_ = mDNS.SetListenOptions(networkConfig.GetMDNSMode())
+				_ = mDNS.SetLocalNames([]string{
+					networkState.GetHostname(),
+					networkState.GetFQDN(),
+				}, true)
+			}
 		},
 	})