Lift double routing detection out of Routing

mobile/src/main/java/be/mygod/vpnhotspot/RoutingManager.kt

@@ -3,7 +3,8 @@ package be.mygod.vpnhotspot
 import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.net.Routing
 import be.mygod.vpnhotspot.net.wifi.WifiDoubleLock
-import be.mygod.vpnhotspot.util.Event0
+import be.mygod.vpnhotspot.util.putIfAbsentCompat
+import be.mygod.vpnhotspot.util.removeCompat
 import be.mygod.vpnhotspot.widget.SmartSnackbar
 import timber.log.Timber
 
@@ -18,11 +19,10 @@ abstract class RoutingManager(private val caller: Any, val downstream: String, p
             }
             set(value) = app.pref.edit().putString(KEY_MASQUERADE_MODE, value.name).apply()
 
-        private val onPreCleanRoutings = Event0()
-        private val onRoutingsCleaned = Event0()
+        private val active = mutableMapOf<String, RoutingManager>()
 
         fun clean() {
-            onPreCleanRoutings()
+            for (manager in active.values) manager.routing?.stop()
             val cleaned = try {
                 Routing.clean()
                 true
@@ -31,7 +31,7 @@ abstract class RoutingManager(private val caller: Any, val downstream: String, p
                 SmartSnackbar.make(e).show()
                 false
             }
-            if (cleaned) onRoutingsCleaned()
+            if (cleaned) for (manager in active.values) manager.initRouting()
         }
     }
 
@@ -47,18 +47,16 @@ abstract class RoutingManager(private val caller: Any, val downstream: String, p
         }
     }
 
-    var started = false
+    val started get() = active[downstream] === this
     private var routing: Routing? = null
     init {
         if (isWifi) WifiDoubleLock.acquire(this)
     }
 
-    fun start(): Boolean {
-        check(!started)
-        started = true
-        onPreCleanRoutings[this] = { routing?.stop() }
-        onRoutingsCleaned[this] = { initRouting() }
-        return initRouting()
+    fun start() = when (active.putIfAbsentCompat(downstream, this)) {
+        null -> initRouting()
+        this -> true    // already started
+        else -> throw IllegalStateException("Double routing detected from $caller")
     }
 
     private fun initRouting() = try {
@@ -81,11 +79,7 @@ abstract class RoutingManager(private val caller: Any, val downstream: String, p
     protected abstract fun Routing.configure()
 
     fun stop() {
-        if (!started) return
-        routing?.revert()
-        onPreCleanRoutings -= this
-        onRoutingsCleaned -= this
-        started = false
+        if (active.removeCompat(downstream, this)) routing?.revert()
     }
 
     fun destroy() {

mobile/src/main/java/be/mygod/vpnhotspot/TetheringService.kt

@@ -50,7 +50,7 @@ class TetheringService : IpNeighbourMonitoringService() {
             val toRemove = downstreams.toMutableMap()   // make a copy
             for (iface in TetheringManager.getTetheredIfaces(extras)) {
                 val downstream = toRemove.remove(iface) ?: continue
-                if (downstream.monitor && !downstream.started) downstream.start()
+                if (downstream.monitor) downstream.start()
             }
             for ((iface, downstream) in toRemove) {
                 if (downstream.monitor) downstream.stop() else downstreams.remove(iface)?.destroy()

mobile/src/main/java/be/mygod/vpnhotspot/net/Routing.kt

@@ -42,11 +42,6 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
          */
         val IPTABLES = if (Build.VERSION.SDK_INT >= 26) "iptables -w 1" else "iptables -w"
 
-        /**
-         * For debugging: check that we do not start a Routing for the same interface twice.
-         */
-        private var downstreams = mutableSetOf<String>()
-
         fun clean() {
             TrafficRecorder.clean()
             RootSession.use {
@@ -60,7 +55,6 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
                 it.execQuiet("while ip rule del priority $RULE_PRIORITY_UPSTREAM; do done")
                 it.execQuiet("while ip rule del priority $RULE_PRIORITY_UPSTREAM_FALLBACK; do done")
             }
-            downstreams.clear()
         }
 
         private fun RootSession.Transaction.iptables(command: String, revert: String) {
@@ -89,10 +83,6 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
         override val message: String get() = app.getString(R.string.exception_interface_not_found)
     }
 
-    init {
-        check(downstreams.add(downstream)) { "Double routing detected from $caller" }
-    }
-
     private val hostAddress = try {
         NetworkInterface.getByName(downstream)!!.interfaceAddresses!!.asSequence().single { it.address is Inet4Address }
     } catch (e: Exception) {
@@ -314,6 +304,5 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
         fallbackUpstream.subrouting?.transaction?.revert()
         upstream.subrouting?.transaction?.revert()
         transaction.revert()
-        check(downstreams.remove(downstream)) { "Double reverting detected from $caller" }
     }
 }

mobile/src/main/java/be/mygod/vpnhotspot/net/monitor/TrafficRecorder.kt

@@ -9,6 +9,7 @@ import be.mygod.vpnhotspot.room.TrafficRecord
 import be.mygod.vpnhotspot.util.Event2
 import be.mygod.vpnhotspot.util.RootSession
 import be.mygod.vpnhotspot.util.parseNumericAddress
+import be.mygod.vpnhotspot.util.putIfAbsentCompat
 import be.mygod.vpnhotspot.widget.SmartSnackbar
 import timber.log.Timber
 import java.net.InetAddress
@@ -28,7 +29,7 @@ object TrafficRecorder {
         AppDatabase.instance.trafficRecordDao.insert(record)
         synchronized(this) {
             DebugHelper.log(TAG, "Registering $ip%$downstream")
-            check(records.put(Pair(ip, downstream), record) == null)
+            check(records.putIfAbsentCompat(Pair(ip, downstream), record) == null)
             scheduleUpdateLocked()
         }
     }

mobile/src/main/java/be/mygod/vpnhotspot/util/Utils.kt

@@ -91,5 +91,14 @@ fun Context.stopAndUnbind(connection: ServiceConnection) {
     unbindService(connection)
 }
 
-fun <K, V> HashMap<K, V>.computeIfAbsentCompat(key: K, value: () -> V) = if (Build.VERSION.SDK_INT >= 26)
+fun <K, V> MutableMap<K, V>.computeIfAbsentCompat(key: K, value: () -> V) = if (Build.VERSION.SDK_INT >= 26)
     computeIfAbsent(key) { value() } else this[key] ?: value().also { put(key, it) }
+fun <K, V> MutableMap<K, V>.putIfAbsentCompat(key: K, value: V) = if (Build.VERSION.SDK_INT >= 24)
+    putIfAbsent(key, value) else this[key] ?: put(key, value)
+fun <K, V> MutableMap<K, V>.removeCompat(key: K, value: V) = if (Build.VERSION.SDK_INT >= 24) remove(key, value) else {
+    val curValue = get(key)
+    if (curValue === value && (curValue != null || containsKey(key))) {
+        remove(key)
+        true
+    } else false
+}