android: RU list - no reconnect for an unchanged list, failure backoff

- same SHA-256 as the applied list: only bump the timestamp, no parse,
  save or tunnel reconnect (it tore a healthy tunnel down daily)
- a failed download is not retried on every cold start (3 h backoff)
- the saved list is read and parsed off the main thread at startup
- switching the split off in system mode reconnects to drop the routes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/frontends/android/app/src/main/java/org/strongswan/android/logic/routing/RuIpListManager.kt

@@ -155,8 +155,10 @@ class RuIpListManager private constructor(private val context: Context)
 			 * classification set is hot-swapped in native code instead */
 			CharonVpnService.pushUserspaceRoutingData(context)
 		}
-		else if (enabled)
+		else if (enabled || excludedV4.isNotEmpty() || excludedV6.isNotEmpty())
-		{
+		{	/* routes only change when the TUN is re-established - also when
+			 * the split is switched OFF, or the RU ranges keep bypassing the
+			 * tunnel until the next manual reconnect */
 			scheduleReconnect()
 		}
 	}
@@ -183,7 +185,17 @@ class RuIpListManager private constructor(private val context: Context)
 		return try
 		{
 			val (text, sha256) = withContext(Dispatchers.IO) { fetchList() }
-			val parsed = withContext(Dispatchers.IO) { parse(text) }
+			if (sha256 == prefs.getString(PREF_SHA256, null) &&
+				(excludedV4.isNotEmpty() || excludedV6.isNotEmpty()))
+			{	/* identical list: nothing to parse, save or re-apply - above
+				 * all no reconnect that tears down a healthy tunnel daily */
+				val now = System.currentTimeMillis()
+				prefs.edit().putLong(PREF_LAST_UPDATE, now).remove(PREF_LAST_FAIL).apply()
+				publish(status = RuIpListStatus.UP_TO_DATE, lastUpdatedMs = now)
+				Log.i(TAG, "RU geoip list unchanged")
+				return true
+			}
+			val parsed = withContext(Dispatchers.Default) { parse(text) }
 			if (parsed.v4.isEmpty() && parsed.v6.isEmpty())
 			{
 				throw IOException("downloaded list contains no CIDRs")
@@ -195,6 +207,7 @@ class RuIpListManager private constructor(private val context: Context)
 			prefs.edit()
 				.putLong(PREF_LAST_UPDATE, now)
 				.putString(PREF_SHA256, sha256)
+				.remove(PREF_LAST_FAIL)
 				.apply()
 			publish(
 				status = RuIpListStatus.UP_TO_DATE,
@@ -213,6 +226,8 @@ class RuIpListManager private constructor(private val context: Context)
 		catch (e: Exception)
 		{
 			Log.w(TAG, "RU geoip list update failed", e)
+			/* remembered so a blocked source is not retried on every cold start */
+			prefs.edit().putLong(PREF_LAST_FAIL, System.currentTimeMillis()).apply()
 			publish(status = RuIpListStatus.ERROR)
 			false
 		}
@@ -224,14 +239,16 @@ class RuIpListManager private constructor(private val context: Context)
 
 	/* ------------------------------ internals ------------------------------ */
 
-	private fun loadFromDisk()
+	private suspend fun loadFromDisk()
 	{
 		val file = listFile()
 		if (file.isFile)
 		{
 			try
 			{
-				val parsed = parse(file.readText())
+				/* thousands of CIDRs: read and parse off the main thread (this
+				 * runs at every process start) */
+				val parsed = withContext(Dispatchers.Default) { parse(file.readText()) }
 				excludedV4 = parsed.v4
 				excludedV6 = parsed.v6
 				publish(
@@ -257,8 +274,8 @@ class RuIpListManager private constructor(private val context: Context)
 		{
 			return
 		}
-		val last = prefs.getLong(PREF_LAST_UPDATE, 0L)
+		if (isAutoCheckDue(System.currentTimeMillis(), prefs.getLong(PREF_LAST_UPDATE, 0L),
-		if (System.currentTimeMillis() - last >= Constants.RUSPLIT_CHECK_INTERVAL_MS)
+						   prefs.getLong(PREF_LAST_FAIL, 0L)))
 		{
 			scope.launch { updateNow() }
 		}
@@ -403,6 +420,21 @@ class RuIpListManager private constructor(private val context: Context)
 		private const val FILE_NAME = "ru.list"
 		private const val PREF_LAST_UPDATE = "rusplit_last_update"
 		private const val PREF_SHA256 = "rusplit_sha256"
+		private const val PREF_LAST_FAIL = "rusplit_last_fail"
+		/* after a failed download wait this long before the next automatic try */
+		internal const val FAIL_RETRY_MS = 3 * 60 * 60 * 1000L
+
+		/** Whether the automatic refresh is due (pure, unit-testable). */
+		@JvmStatic
+		internal fun isAutoCheckDue(now: Long, lastUpdate: Long, lastFail: Long): Boolean
+		{
+			if (now - lastUpdate < Constants.RUSPLIT_CHECK_INTERVAL_MS)
+			{
+				return false
+			}
+			/* clock moved backwards: don't let a "future" failure block forever */
+			return lastFail <= 0L || lastFail > now || now - lastFail >= FAIL_RETRY_MS
+		}
 		private const val RECONNECT_DEBOUNCE_MS = 2000L
 		private const val CONNECT_TIMEOUT_MS = 10_000
 		private const val READ_TIMEOUT_MS = 30_000

src/frontends/android/app/src/test/java/org/strongswan/android/logic/routing/RuIpListManagerTest.kt

@@ -290,4 +290,20 @@ class RuIpListManagerTest
 		assertThat(fit).isNotNull()
 		assertThat(RuIpListManager.subtractAndSplit(ranges4, fit!!.first, 6000)).isNotNull()
 	}
+
+	/* ---------------- auto check ---------------- */
+
+	@Test
+	fun autoCheckWaitsForTheIntervalAndBacksOffAfterFailures()
+	{
+		val day = org.strongswan.android.utils.Constants.RUSPLIT_CHECK_INTERVAL_MS
+		val now = 10 * day
+		assertThat(RuIpListManager.isAutoCheckDue(now, now - day / 2, 0L)).isFalse()
+		assertThat(RuIpListManager.isAutoCheckDue(now, now - day, 0L)).isTrue()
+		/* a recent failure blocks retries on every cold start */
+		assertThat(RuIpListManager.isAutoCheckDue(now, 0L, now - 60_000)).isFalse()
+		assertThat(RuIpListManager.isAutoCheckDue(now, 0L, now - RuIpListManager.FAIL_RETRY_MS)).isTrue()
+		/* a failure stamped in the future (clock change) never blocks */
+		assertThat(RuIpListManager.isAutoCheckDue(now, 0L, now + 60_000)).isTrue()
+	}
 }