Revert "Remove fallback upstream monitor"

This commit reverts 99e721bf7e.

Fixes #119.

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

@@ -48,7 +48,7 @@ abstract class RoutingManager(private val caller: Any, val downstream: String, p
             ipForward() // local only interfaces need to enable ip_forward
             forward()
             masquerade(masqueradeMode)
-            commit(true)
+            commit()
         }
     }
 

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

@@ -11,6 +11,7 @@ import androidx.preference.SwitchPreference
 import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.net.Routing.Companion.IPTABLES
 import be.mygod.vpnhotspot.net.TetherOffloadManager
+import be.mygod.vpnhotspot.net.monitor.FallbackUpstreamMonitor
 import be.mygod.vpnhotspot.net.monitor.IpMonitor
 import be.mygod.vpnhotspot.net.monitor.UpstreamMonitor
 import be.mygod.vpnhotspot.net.wifi.WifiDoubleLock
@@ -115,6 +116,9 @@ class SettingsPreferenceFragment : PreferenceFragmentCompat() {
                         |echo iptables -nvx -L vpnhotspot_fwd
                         |$IPTABLES -nvx -L vpnhotspot_fwd
                         |echo
+                        |echo iptables -nvx -L vpnhotspot_acl
+                        |$IPTABLES -nvx -L vpnhotspot_acl
+                        |echo
                         |echo logcat-su
                         |logcat -d
                     """.trimMargin())
@@ -146,23 +150,24 @@ class SettingsPreferenceFragment : PreferenceFragmentCompat() {
 
     override fun onDisplayPreferenceDialog(preference: Preference) {
         when (preference.key) {
-            UpstreamMonitor.KEY -> AlwaysAutoCompleteEditTextPreferenceDialogFragmentCompat().apply {
+            UpstreamMonitor.KEY, FallbackUpstreamMonitor.KEY ->
-                setArguments(preference.key, try {
+                AlwaysAutoCompleteEditTextPreferenceDialogFragmentCompat().apply {
-                    NetworkInterface.getNetworkInterfaces().asSequence()
+                    setArguments(preference.key, try {
-                            .filter {
+                        NetworkInterface.getNetworkInterfaces().asSequence()
-                                try {
+                                .filter {
-                                    it.isUp && !it.isLoopback && it.interfaceAddresses.isNotEmpty()
+                                    try {
-                                } catch (_: SocketException) {
+                                        it.isUp && !it.isLoopback && it.interfaceAddresses.isNotEmpty()
-                                    false
+                                    } catch (_: SocketException) {
+                                        false
+                                    }
                                 }
-                            }
+                                .map { it.name }.sorted().toList().toTypedArray()
-                            .map { it.name }.sorted().toList().toTypedArray()
+                    } catch (e: SocketException) {
-                } catch (e: SocketException) {
+                        Timber.d(e)
-                    Timber.d(e)
+                        emptyArray<String>()
-                    emptyArray<String>()
+                    })
-                })
+                    setTargetFragment(this@SettingsPreferenceFragment, 0)
-                setTargetFragment(this@SettingsPreferenceFragment, 0)
+                }.show(fragmentManager ?: return, preference.key)
-            }.show(fragmentManager ?: return, preference.key)
             else -> super.onDisplayPreferenceDialog(preference)
         }
     }

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

@@ -5,7 +5,7 @@ import android.os.Build
 import androidx.annotation.RequiresApi
 import be.mygod.vpnhotspot.App.Companion.app
 import be.mygod.vpnhotspot.R
-import be.mygod.vpnhotspot.net.monitor.DefaultNetworkMonitor
+import be.mygod.vpnhotspot.net.monitor.FallbackUpstreamMonitor
 import be.mygod.vpnhotspot.net.monitor.IpNeighbourMonitor
 import be.mygod.vpnhotspot.net.monitor.TrafficRecorder
 import be.mygod.vpnhotspot.net.monitor.UpstreamMonitor
@@ -52,6 +52,8 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
                 it.execQuiet("while $IPTABLES -D FORWARD -j vpnhotspot_fwd; do done")
                 it.execQuiet("$IPTABLES -F vpnhotspot_fwd")
                 it.execQuiet("$IPTABLES -X vpnhotspot_fwd")
+                it.execQuiet("$IPTABLES -F vpnhotspot_acl")
+                it.execQuiet("$IPTABLES -X vpnhotspot_acl")
                 it.execQuiet("while $IPTABLES -t nat -D POSTROUTING -j vpnhotspot_masquerade; do done")
                 it.execQuiet("$IPTABLES -t nat -F vpnhotspot_masquerade")
                 it.execQuiet("$IPTABLES -t nat -X vpnhotspot_masquerade")
@@ -120,17 +122,23 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
          */
         inner class Subrouting(priority: Int, val upstream: String? = null) {
             val transaction = RootSession.beginTransaction().safeguard {
-                if (upstream != null) ipRule("from all", downstream, upstream, priority)
+                if (upstream != null) {
-                fun simpleMasquerade() {
+                    ipRule("from all", downstream, upstream, priority)
-                    // note: specifying -i wouldn't work for POSTROUTING
+                    iptablesInsert("vpnhotspot_fwd -i $downstream -o $upstream -j vpnhotspot_acl")
-                    iptablesAdd(if (upstream == null) "vpnhotspot_masquerade -s $hostSubnet -j MASQUERADE" else
+                    iptablesInsert("vpnhotspot_fwd -i $upstream -o $downstream -m state --state ESTABLISHED,RELATED -j vpnhotspot_acl")
-                        "vpnhotspot_masquerade -s $hostSubnet -o $upstream -j MASQUERADE", "nat")
+                } else {
+                    iptablesInsert("vpnhotspot_fwd -i $downstream -j vpnhotspot_acl")
+                    iptablesInsert("vpnhotspot_fwd -o $downstream -m state --state ESTABLISHED,RELATED -j vpnhotspot_acl")
                 }
                 @TargetApi(28) when (masqueradeMode) {
                     MasqueradeMode.None -> { }  // nothing to be done here
-                    MasqueradeMode.Simple -> simpleMasquerade()
+                    MasqueradeMode.Simple -> {
-                    // fallback is only needed for repeater on API 23
+                        // note: specifying -i wouldn't work for POSTROUTING
-                    MasqueradeMode.Netd -> if (upstream == null) simpleMasquerade() else {
+                        iptablesAdd(if (upstream == null) "vpnhotspot_masquerade -s $hostSubnet -j MASQUERADE" else
+                            "vpnhotspot_masquerade -s $hostSubnet -o $upstream -j MASQUERADE", "nat")
+                    }
+                    MasqueradeMode.Netd -> {
+                        check(upstream != null) // fallback is only needed for repeater on API 23 < 28
                         /**
                          * 0 means that there are no interface addresses coming after, which is unused anyway.
                          *
@@ -166,7 +174,7 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
         override fun onLost() = synchronized(this@Routing) {
             val subrouting = subrouting ?: return
             // we could be removing fallback subrouting which no collision could ever happen, check before removing
-            if (subrouting.upstream != null) check(upstreams.remove(subrouting.upstream))
+            subrouting.upstream?.let { check(upstreams.remove(it)) }
             subrouting.transaction.revert()
             this.subrouting = null
             dns = emptyList()
@@ -191,8 +199,8 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
     private inner class Client(private val ip: Inet4Address, mac: Long) : AutoCloseable {
         private val transaction = RootSession.beginTransaction().safeguard {
             val address = ip.hostAddress
-            iptablesInsert("vpnhotspot_fwd -i $downstream -s $address -j ACCEPT")
+            iptablesInsert("vpnhotspot_acl -i $downstream -s $address -j ACCEPT")
-            iptablesInsert("vpnhotspot_fwd -o $downstream -d $address -m state --state ESTABLISHED,RELATED -j ACCEPT")
+            iptablesInsert("vpnhotspot_acl -o $downstream -d $address -j ACCEPT")
         }
 
         init {
@@ -261,6 +269,7 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
 
     fun forward() {
         transaction.execQuiet("$IPTABLES -N vpnhotspot_fwd")
+        transaction.execQuiet("$IPTABLES -N vpnhotspot_acl")
         transaction.iptablesInsert("FORWARD -j vpnhotspot_fwd")
         transaction.iptablesAdd("vpnhotspot_fwd -i $downstream ! -o $downstream -j DROP")   // ensure blocking works
         // the real forwarding filters will be added in Subrouting when clients are connected
@@ -306,15 +315,14 @@ class Routing(private val caller: Any, private val downstream: String) : IpNeigh
 
     fun stop() {
         IpNeighbourMonitor.unregisterCallback(this)
-        DefaultNetworkMonitor.unregisterCallback(fallbackUpstream)
+        FallbackUpstreamMonitor.unregisterCallback(fallbackUpstream)
         UpstreamMonitor.unregisterCallback(upstream)
     }
 
-    fun commit(localOnly: Boolean = false) {
+    fun commit() {
         transaction.commit()
         Timber.i("Started routing for $downstream by $caller")
-        @TargetApi(28)
+        FallbackUpstreamMonitor.registerCallback(fallbackUpstream)
-        if (localOnly || masqueradeMode != MasqueradeMode.Netd) DefaultNetworkMonitor.registerCallback(fallbackUpstream)
         UpstreamMonitor.registerCallback(upstream)
         IpNeighbourMonitor.registerCallback(this)
     }

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

@@ -0,0 +1,41 @@
+package be.mygod.vpnhotspot.net.monitor
+
+import android.content.SharedPreferences
+import be.mygod.vpnhotspot.App.Companion.app
+
+abstract class FallbackUpstreamMonitor private constructor() : UpstreamMonitor() {
+    companion object : SharedPreferences.OnSharedPreferenceChangeListener {
+        const val KEY = "service.upstream.fallback"
+
+        init {
+            app.pref.registerOnSharedPreferenceChangeListener(this)
+        }
+
+        private fun generateMonitor(): UpstreamMonitor {
+            val upstream = app.pref.getString(KEY, null)
+            return if (upstream.isNullOrEmpty()) DefaultNetworkMonitor else InterfaceMonitor(upstream)
+        }
+        private var monitor = generateMonitor()
+
+        fun registerCallback(callback: Callback) = synchronized(this) { monitor.registerCallback(callback) }
+        fun unregisterCallback(callback: Callback) = synchronized(this) { monitor.unregisterCallback(callback) }
+
+        override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences?, key: String?) {
+            if (key == KEY) synchronized(this) {
+                val old = monitor
+                val callbacks = synchronized(old) {
+                    val callbacks = old.callbacks.toList()
+                    old.callbacks.clear()
+                    old.destroyLocked()
+                    callbacks
+                }
+                val new = generateMonitor()
+                monitor = new
+                for (callback in callbacks) {
+                    callback.onLost()
+                    new.registerCallback(callback)
+                }
+            }
+        }
+    }
+}

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

@@ -62,7 +62,7 @@ object TrafficRecorder {
     private fun doUpdate(timestamp: Long) {
         val oldRecords = LongSparseArray<TrafficRecord>()
         loop@ for (line in RootSession.use {
-            val command = "$IPTABLES -nvx -L vpnhotspot_fwd"
+            val command = "$IPTABLES -nvx -L vpnhotspot_acl"
             val result = it.execQuiet(command)
             val message = RootSession.checkOutput(command, result, false, false)
             if (result.err.isNotEmpty()) Timber.i(message)

mobile/src/main/res/drawable/ic_action_settings_input_component.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0"
+        android:tint="?attr/colorControlNormal">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M5,2c0,-0.55 -0.45,-1 -1,-1s-1,0.45 -1,1v4L1,6v6h6L7,6L5,6L5,2zM9,16c0,1.3 0.84,2.4 2,2.82L11,23h2v-4.18c1.16,-0.41 2,-1.51 2,-2.82v-2L9,14v2zM1,16c0,1.3 0.84,2.4 2,2.82L3,23h2v-4.18C6.16,18.4 7,17.3 7,16v-2L1,14v2zM21,6L21,2c0,-0.55 -0.45,-1 -1,-1s-1,0.45 -1,1v4h-2v6h6L23,6h-2zM13,2c0,-0.55 -0.45,-1 -1,-1s-1,0.45 -1,1v4L9,6v6h6L15,6h-2L13,2zM17,16c0,1.3 0.84,2.4 2,2.82L19,23h2v-4.18c1.16,-0.41 2,-1.51 2,-2.82v-2h-6v2z"/>
+</vector>

mobile/src/main/res/values-zh-rCN/strings.xml

@@ -99,6 +99,8 @@
     <string name="settings_service_ip_monitor_poll_root">轮询 (root)</string>
     <string name="settings_service_upstream">上游网络接口</string>
     <string name="settings_service_upstream_auto">自动检测系统 VPN</string>
+    <string name="settings_upstream_fallback">备用上游接口</string>
+    <string name="settings_upstream_fallback_auto">自动检测系统默认网络</string>
     <string name="settings_service_clean">清理/重新应用路由规则</string>
     <string name="settings_service_clean_summary">将修改的设置应用到当前启用的服务上。也可用于修复偶尔会发生的竞态条件。</string>
     <string name="settings_service_dhcp_workaround">尝试修复 DHCP</string>

mobile/src/main/res/values/strings.xml

@@ -104,6 +104,8 @@
     <string name="settings_service_ip_monitor_poll_root">Poll with root</string>
     <string name="settings_service_upstream">Upstream network interface</string>
     <string name="settings_service_upstream_auto">Auto detect system VPN</string>
+    <string name="settings_upstream_fallback">Fallback upstream interface</string>
+    <string name="settings_upstream_fallback_auto">Auto detect system default network</string>
     <string name="settings_service_dhcp_workaround">Enable DHCP workaround</string>
     <string name="settings_service_dhcp_workaround_summary">Use this if clients cannot obtain IP addresses.</string>
     <string name="settings_service_clean">Clean/reapply routing rules</string>

mobile/src/main/res/xml/pref_settings.xml

@@ -12,6 +12,11 @@
             app:icon="@drawable/ic_action_settings_ethernet"
             app:title="@string/settings_service_upstream"
             app:summary="@string/settings_service_upstream_auto"/>
+        <be.mygod.vpnhotspot.preference.AlwaysAutoCompleteEditTextPreference
+            app:key="service.upstream.fallback"
+            app:icon="@drawable/ic_action_settings_input_component"
+            app:title="@string/settings_upstream_fallback"
+            app:summary="@string/settings_upstream_fallback_auto"/>
         <com.takisoft.preferencex.SimpleMenuPreference
             app:key="service.masqueradeMode"
             app:icon="@drawable/ic_social_people"