Revert "Revert "android: add UI to run as exit node (#230)" (#235)" (#237)

This reverts commit 0d1a3cf415.

Signed-off-by: Andrea Gottardo <andrea@gottardo.me>

android/src/main/java/com/tailscale/ipn/MainActivity.kt

@@ -37,6 +37,7 @@ import com.tailscale.ipn.ui.view.MainViewNavigation
 import com.tailscale.ipn.ui.view.ManagedByView
 import com.tailscale.ipn.ui.view.MullvadExitNodePicker
 import com.tailscale.ipn.ui.view.PeerDetails
+import com.tailscale.ipn.ui.view.RunExitNodeView
 import com.tailscale.ipn.ui.view.Settings
 import com.tailscale.ipn.ui.view.UserSwitcherView
 import com.tailscale.ipn.ui.viewModel.ExitNodePickerNav
@@ -91,7 +92,9 @@ class MainActivity : ComponentActivity() {
                   onNavigateHome = {
                     navController.popBackStack(route = "main", inclusive = false)
                   },
-                  onNavigateToMullvadCountry = { navController.navigate("mullvad/$it") })
+                  onNavigateToExitNodePicker = { navController.popBackStack() },
+                  onNavigateToMullvadCountry = { navController.navigate("mullvad/$it") },
+                  onNavigateToRunAsExitNode = { navController.navigate("runExitNode") })
 
           composable("main") { MainView(navigation = mainViewNav) }
           composable("settings") { Settings(settingsNav) }
@@ -103,6 +106,9 @@ class MainActivity : ComponentActivity() {
                   MullvadExitNodePicker(
                       it.arguments!!.getString("countryCode")!!, exitNodePickerNav)
                 }
+              composable("runExitNode") {
+                  RunExitNodeView(exitNodePickerNav)
+              }
           }
           composable(
               "peerDetails/{nodeId}",

android/src/main/java/com/tailscale/ipn/ui/model/Ipn.kt

@@ -111,7 +111,7 @@ class Ipn {
         ShieldsUpSet = true
       }
 
-    var AdvertiseRoutes: Boolean? = null
+    var AdvertiseRoutes: List<String>? = null
       set(value) {
         field = value
         AdvertiseRoutesSet = true

android/src/main/java/com/tailscale/ipn/ui/view/ExitNodePicker.kt

@@ -15,6 +15,7 @@ import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.outlined.KeyboardArrowRight
 import androidx.compose.material.icons.outlined.Check
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.ListItem
 import androidx.compose.material3.MaterialTheme
@@ -25,7 +26,6 @@ import androidx.compose.runtime.collectAsState
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.text.font.FontStyle
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
@@ -50,6 +50,11 @@ fun ExitNodePicker(
       val anyActive = model.anyActive.collectAsState()
 
       LazyColumn(modifier = Modifier.padding(innerPadding)) {
+        item(key = "runExitNode") {
+          RunAsExitNodeItem(nav = nav, viewModel = model)
+          HorizontalDivider()
+        }
+
         item(key = "none") {
           ExitNodeItem(
               model,
@@ -132,9 +137,27 @@ fun ExitNodeItem(
               Icon(Icons.Outlined.Check, contentDescription = stringResource(R.string.more))
             } else if (!node.online) {
               Spacer(modifier = Modifier.width(8.dp))
-              Text(stringResource(R.string.offline), fontStyle = FontStyle.Italic)
+              Text(stringResource(R.string.offline))
             }
           }
         })
   }
 }
+
+@Composable
+fun RunAsExitNodeItem(nav: ExitNodePickerNav, viewModel: ExitNodePickerViewModel) {
+  val isRunningExitNode = viewModel.isRunningExitNode.collectAsState().value
+
+  Box {
+    ListItem(
+        modifier = Modifier.clickable { nav.onNavigateToRunAsExitNode() },
+        headlineContent = { Text(stringResource(id = R.string.run_as_exit_node)) },
+        trailingContent = {
+          if (isRunningExitNode) {
+            Text(stringResource(R.string.enabled))
+          } else {
+            Text(stringResource(R.string.disabled))
+          }
+        })
+  }
+}

android/src/main/java/com/tailscale/ipn/ui/view/RunExitNodeView.kt

@@ -0,0 +1,115 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package com.tailscale.ipn.ui.view
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxHeight
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.outlined.ArrowForward
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.viewmodel.compose.viewModel
+import com.tailscale.ipn.R
+import com.tailscale.ipn.ui.theme.ts_color_light_blue
+import com.tailscale.ipn.ui.util.LoadingIndicator
+import com.tailscale.ipn.ui.viewModel.ExitNodePickerNav
+import com.tailscale.ipn.ui.viewModel.RunExitNodeViewModel
+import com.tailscale.ipn.ui.viewModel.RunExitNodeViewModelFactory
+
+@Composable
+fun RunExitNodeView(
+    nav: ExitNodePickerNav,
+    model: RunExitNodeViewModel = viewModel(factory = RunExitNodeViewModelFactory())
+) {
+  val isRunningExitNode = model.isRunningExitNode.collectAsState().value
+
+  Scaffold(
+      topBar = { Header(R.string.run_as_exit_node, onBack = nav.onNavigateToExitNodePicker) }) {
+          innerPadding ->
+        LoadingIndicator.Wrap {
+          Column(
+              horizontalAlignment = Alignment.CenterHorizontally,
+              verticalArrangement =
+                  Arrangement.spacedBy(16.dp, alignment = Alignment.Top),
+              modifier = Modifier.padding(innerPadding).padding(16.dp).fillMaxHeight()) {
+                RunExitNodeGraphic()
+
+                if (isRunningExitNode) {
+                  Text(
+                      stringResource(R.string.running_as_exit_node),
+                      fontFamily = MaterialTheme.typography.titleLarge.fontFamily,
+                      fontSize = MaterialTheme.typography.titleLarge.fontSize,
+                      fontWeight = FontWeight.SemiBold)
+                  Text(stringResource(R.string.run_exit_node_explainer_running))
+                } else {
+                  Text(
+                      stringResource(R.string.run_this_device_as_an_exit_node),
+                      fontFamily = MaterialTheme.typography.titleLarge.fontFamily,
+                      fontSize = MaterialTheme.typography.titleLarge.fontSize,
+                      fontWeight = FontWeight.SemiBold)
+                  Text(stringResource(R.string.run_exit_node_explainer))
+                }
+                Text(stringResource(R.string.run_exit_node_caution), color = Color.Red)
+
+                PrimaryActionButton(onClick = { model.setRunningExitNode(!isRunningExitNode) }) {
+                  if (isRunningExitNode) {
+                    Text(stringResource(R.string.stop_running_as_exit_node))
+                  } else {
+                    Text(stringResource(R.string.start_running_as_exit_node))
+                  }
+                }
+              }
+        }
+      }
+}
+
+@Composable
+fun RunExitNodeGraphic() {
+  @Composable
+  fun ArrowForward() {
+    Icon(
+        Icons.AutoMirrored.Outlined.ArrowForward,
+        "Arrow Forward",
+        tint = MaterialTheme.colorScheme.secondary,
+        modifier = Modifier.size(24.dp))
+  }
+
+  Row(
+      horizontalArrangement = Arrangement.spacedBy(8.dp),
+      verticalAlignment = Alignment.CenterVertically,
+      modifier = Modifier.padding(vertical = 18.dp)) {
+        Icon(
+            painter = painterResource(id = R.drawable.computer),
+            "Computer icon",
+            tint = ts_color_light_blue,
+            modifier = Modifier.size(36.dp))
+        ArrowForward()
+        Icon(
+            painter = painterResource(id = R.drawable.android),
+            "Android icon",
+            tint = ts_color_light_blue,
+            modifier = Modifier.size(36.dp))
+        ArrowForward()
+        Icon(
+            painter = painterResource(id = R.drawable.globe),
+            "Globe icon",
+            tint = ts_color_light_blue,
+            modifier = Modifier.size(36.dp))
+      }
+}

android/src/main/java/com/tailscale/ipn/ui/viewModel/ExitNodePickerViewModel.kt

@@ -12,16 +12,18 @@ import com.tailscale.ipn.ui.model.StableNodeID
 import com.tailscale.ipn.ui.notifier.Notifier
 import com.tailscale.ipn.ui.util.LoadingIndicator
 import com.tailscale.ipn.ui.util.set
-import java.util.TreeMap
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
+import java.util.TreeMap
 
 data class ExitNodePickerNav(
     val onNavigateHome: () -> Unit,
+    val onNavigateToExitNodePicker: () -> Unit,
     val onNavigateToMullvadCountry: (String) -> Unit,
+    val onNavigateToRunAsExitNode: () -> Unit,
 )
 
 class ExitNodePickerViewModelFactory(private val nav: ExitNodePickerNav) :
@@ -49,6 +51,7 @@ class ExitNodePickerViewModel(private val nav: ExitNodePickerNav) : IpnViewModel
       MutableStateFlow(TreeMap())
   val mullvadBestAvailableByCountry: StateFlow<Map<String, ExitNode>> = MutableStateFlow(TreeMap())
   val anyActive: StateFlow<Boolean> = MutableStateFlow(false)
+    val isRunningExitNode: StateFlow<Boolean> = MutableStateFlow(false)
 
   init {
     viewModelScope.launch {
@@ -56,6 +59,7 @@ class ExitNodePickerViewModel(private val nav: ExitNodePickerNav) : IpnViewModel
           .combine(Notifier.prefs) { netmap, prefs -> Pair(netmap, prefs) }
           .stateIn(viewModelScope)
           .collect { (netmap, prefs) ->
+              isRunningExitNode.set(prefs?.let { AdvertisedRoutesHelper.exitNodeOnFromPrefs(it) })
             val exitNodeId = prefs?.ExitNodeID
             netmap?.Peers?.let { peers ->
               val allNodes =

android/src/main/java/com/tailscale/ipn/ui/viewModel/RunExitNodeViewModel.kt

@@ -0,0 +1,97 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package com.tailscale.ipn.ui.viewModel
+
+import android.util.Log
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewModelScope
+import com.tailscale.ipn.ui.localapi.Client
+import com.tailscale.ipn.ui.model.Ipn
+import com.tailscale.ipn.ui.notifier.Notifier
+import com.tailscale.ipn.ui.util.LoadingIndicator
+import com.tailscale.ipn.ui.util.set
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
+
+class RunExitNodeViewModelFactory() : ViewModelProvider.Factory {
+  override fun <T : ViewModel> create(modelClass: Class<T>): T {
+    return RunExitNodeViewModel() as T
+  }
+}
+
+class AdvertisedRoutesHelper() {
+  companion object {
+    fun exitNodeOnFromPrefs(prefs: Ipn.Prefs): Boolean {
+      var v4 = false
+      var v6 = false
+      prefs.AdvertiseRoutes?.forEach {
+        if (it == "0.0.0.0/0") {
+          v4 = true
+        }
+        if (it == "::/0") {
+          v6 = true
+        }
+      }
+      return v4 && v6
+    }
+  }
+}
+
+class RunExitNodeViewModel() : IpnViewModel() {
+
+  val isRunningExitNode: StateFlow<Boolean> = MutableStateFlow(false)
+  var lastPrefs: Ipn.Prefs? = null
+
+  init {
+    viewModelScope.launch {
+      Notifier.prefs.stateIn(viewModelScope).collect { prefs ->
+        Log.d("RunExitNode", "prefs: AdvertiseRoutes=" + prefs?.AdvertiseRoutes.toString())
+        prefs?.let {
+          lastPrefs = it
+          isRunningExitNode.set(AdvertisedRoutesHelper.exitNodeOnFromPrefs(it))
+        } ?: run { isRunningExitNode.set(false) }
+      }
+    }
+  }
+
+  fun setRunningExitNode(isOn: Boolean) {
+    LoadingIndicator.start()
+    lastPrefs?.let { currentPrefs ->
+      val newPrefs: Ipn.MaskedPrefs
+      if (isOn) {
+        newPrefs = setZeroRoutes(currentPrefs)
+      } else {
+        newPrefs = removeAllZeroRoutes(currentPrefs)
+      }
+      Client(viewModelScope).editPrefs(newPrefs) { result ->
+        LoadingIndicator.stop()
+        Log.d("RunExitNodeViewModel", "Edited prefs: $result")
+      }
+    }
+  }
+
+  private fun setZeroRoutes(prefs: Ipn.Prefs): Ipn.MaskedPrefs {
+    val newRoutes = (removeAllZeroRoutes(prefs).AdvertiseRoutes ?: emptyList()).toMutableList()
+    newRoutes.add("0.0.0.0/0")
+    newRoutes.add("::/0")
+    val newPrefs = Ipn.MaskedPrefs()
+    newPrefs.AdvertiseRoutes = newRoutes
+    return newPrefs
+  }
+
+  private fun removeAllZeroRoutes(prefs: Ipn.Prefs): Ipn.MaskedPrefs {
+    val newRoutes = emptyList<String>().toMutableList()
+    (prefs.AdvertiseRoutes ?: emptyList()).forEach {
+      if (it != "0.0.0.0/0" && it != "::/0") {
+        newRoutes.add(it)
+      }
+    }
+    val newPrefs = Ipn.MaskedPrefs()
+    newPrefs.AdvertiseRoutes = newRoutes
+    return newPrefs
+  }
+}

android/src/main/res/drawable/android.xml

@@ -0,0 +1,5 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:height="24dp" android:tint="#000000" android:viewportHeight="24" android:viewportWidth="24" android:width="24dp">
+      
+    <path android:fillColor="@android:color/white" android:pathData="M17.6,9.48l1.84,-3.18c0.16,-0.31 0.04,-0.69 -0.26,-0.85c-0.29,-0.15 -0.65,-0.06 -0.83,0.22l-1.88,3.24c-2.86,-1.21 -6.08,-1.21 -8.94,0L5.65,5.67c-0.19,-0.29 -0.58,-0.38 -0.87,-0.2C4.5,5.65 4.41,6.01 4.56,6.3L6.4,9.48C3.3,11.25 1.28,14.44 1,18h22C22.72,14.44 20.7,11.25 17.6,9.48zM7,15.25c-0.69,0 -1.25,-0.56 -1.25,-1.25c0,-0.69 0.56,-1.25 1.25,-1.25S8.25,13.31 8.25,14C8.25,14.69 7.69,15.25 7,15.25zM17,15.25c-0.69,0 -1.25,-0.56 -1.25,-1.25c0,-0.69 0.56,-1.25 1.25,-1.25s1.25,0.56 1.25,1.25C18.25,14.69 17.69,15.25 17,15.25z"/>
+    
+</vector>

android/src/main/res/drawable/computer.xml

@@ -0,0 +1,5 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:height="24dp" android:tint="#000000" android:viewportHeight="960" android:viewportWidth="960" android:width="24dp">
+      
+    <path android:fillColor="@android:color/white" android:pathData="M40,840L40,760L920,760L920,840L40,840ZM160,720Q127,720 103.5,696.5Q80,673 80,640L80,200Q80,167 103.5,143.5Q127,120 160,120L800,120Q833,120 856.5,143.5Q880,167 880,200L880,640Q880,673 856.5,696.5Q833,720 800,720L160,720ZM160,640L800,640Q800,640 800,640Q800,640 800,640L800,200Q800,200 800,200Q800,200 800,200L160,200Q160,200 160,200Q160,200 160,200L160,640Q160,640 160,640Q160,640 160,640ZM160,640Q160,640 160,640Q160,640 160,640L160,200Q160,200 160,200Q160,200 160,200L160,200Q160,200 160,200Q160,200 160,200L160,640Q160,640 160,640Q160,640 160,640L160,640Z"/>
+    
+</vector>

android/src/main/res/drawable/globe.xml

@@ -0,0 +1,5 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:height="24dp" android:tint="#000000" android:viewportHeight="24" android:viewportWidth="24" android:width="24dp">
+      
+    <path android:fillColor="@android:color/white" android:pathData="M12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zM4,12c0,-0.61 0.08,-1.21 0.21,-1.78L8.99,15v1c0,1.1 0.9,2 2,2v1.93C7.06,19.43 4,16.07 4,12zM17.89,17.4c-0.26,-0.81 -1,-1.4 -1.9,-1.4h-1v-3c0,-0.55 -0.45,-1 -1,-1h-6v-2h2c0.55,0 1,-0.45 1,-1L10.99,7h2c1.1,0 2,-0.9 2,-2v-0.41C17.92,5.77 20,8.65 20,12c0,2.08 -0.81,3.98 -2.11,5.4z"/>
+    
+</vector>

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

@@ -12,7 +12,7 @@
     <string name="empty"> </string>
     <string name="template">%s</string>
     <string name="more">More</string>
-    <string name="offline">offline</string>
+    <string name="offline">Offline</string>
     <string name="ok">OK</string>
 
     <!-- Strings for the about screen -->
@@ -90,5 +90,15 @@
     <string name="tailnet_exit_nodes">Tailnet Exit Nodes</string>
     <string name="mullvad_exit_nodes">Mullvad VPN</string>
     <string name="best_available">Best Available</string>
+    <string name="run_as_exit_node">Run as Exit Node</string>
+    <string name="run_this_device_as_an_exit_node">Run this device as an exit node?</string>
+    <string name="run_exit_node_explainer">Other devices in your tailnet will be able to route their Internet traffic through this Android device. Make sure to approve this exit node in the admin console in order for other devices to see it.</string>
+    <string name="run_exit_node_caution">Caution: Running an exit node will severely impact battery life. On a metered data plan, significant cellular data charges may also apply. Always disable this feature when no longer needed.</string>
+    <string name="stop_running_as_exit_node">Stop Running as Exit Node</string>
+    <string name="start_running_as_exit_node">Start Running as Exit Node</string>
+    <string name="running_as_exit_node">Now Running as Exit Node</string>
+    <string name="run_exit_node_explainer_running">Other devices in your tailnet can now route their Internet traffic through this Android device. Make sure to approve this exit node in the admin console in order for other devices to see it.</string>
+    <string name="enabled">Enabled</string>
+    <string name="disabled">Disabled</string>
 
 </resources>