feat: implement Android connectivity detection

Cargo.toml

@@ -18,5 +18,8 @@ tracing = { version = "0.1.41", default-features = false, features = ["std", "lo
 [target.'cfg(windows)'.dependencies]
 windows = { version = "0.62.2", features = ["Networking_Connectivity"] }
 
+[target.'cfg(target_os = "linux")'.dependencies]
+zbus = "=5.14.0"
+
 [build-dependencies]
 tauri-plugin = { version = "2.5.1", features = ["build"] }

README.md

@@ -17,11 +17,12 @@ decisions.
    * Detect connection type (WiFi, Ethernet, Cellular)
    * Query metered and constrained status for network policy decisions
    * Check internet reachability
-   * Cross-platform support (Windows, iOS, Android)
+   * Cross-platform support (Windows, Linux, iOS, Android)
 
 | Platform | Supported |
 | -------- | --------- |
 | Windows  | Yes       |
+| Linux    | Yes       |
 | macOS    | Planned   |
 | Android  | Planned   |
 | iOS      | Planned   |
@@ -68,6 +69,12 @@ Run Rust tests only:
 cargo test --workspace --lib
 ```
 
+### Manual Linux scenario testing
+
+See [Linux Connectivity Manual Testing](docs/linux-connectivity-manual-testing.md)
+for WSL2, VirtualBox, NetworkManager, ModemManager, metered, constrained, and
+transport-type test scenarios.
+
 ## Install
 
 _This plugin requires a Rust version of at least **1.94.0**_
@@ -180,11 +187,12 @@ The `connectionStatus()` function returns a `ConnectionStatus` object:
 
 #### Platform mapping
 
-| Field            | Windows                                                                             | iOS                         | Android                            |
-| ---------------- | ----------------------------------------------------------------------------------- | --------------------------- | ---------------------------------- |
-| `metered`        | `NetworkCostType` Unknown/Fixed/Variable                                            | `NWPath.isExpensive`        | absence of `NOT_METERED`           |
-| `constrained`    | `ConstrainedInternetAccess`, data-limit, roaming, or background data restrictions   | `NWPath.isConstrained`      | Data Saver / `RESTRICT_BACKGROUND` |
-| `connectionType` | WWAN/WLAN/IANA interface type                                                       | `NWInterface.InterfaceType` | `TRANSPORT_*` capabilities         |
+| Field            | Windows                                                                             | Linux                                             | iOS                         | Android                            |
+| ---------------- | ----------------------------------------------------------------------------------- | ------------------------------------------------- | --------------------------- | ---------------------------------- |
+| `connected`      | `InternetAccess` or `ConstrainedInternetAccess`                                     | NetworkManager `FULL`/`PORTAL` or up default route fallback | `NWPath.status` satisfied   | active network with internet capability |
+| `metered`        | `NetworkCostType` Unknown/Fixed/Variable                                            | NetworkManager primary device `Metered`           | `NWPath.isExpensive`        | absence of `NOT_METERED`           |
+| `constrained`    | `ConstrainedInternetAccess`, data-limit, roaming, or background data restrictions   | NetworkManager portal/metered or cellular roaming; fallback defaults to `false` | `NWPath.isConstrained`      | Data Saver / `RESTRICT_BACKGROUND` |
+| `connectionType` | WWAN/WLAN/IANA interface type                                                       | NetworkManager device type or sysfs fallback      | `NWInterface.InterfaceType` | `TRANSPORT_*` capabilities         |
 
 ## Development Standards
 

android/.gitignore

@@ -0,0 +1,3 @@
+**/build/
+/.gradle
+/.tauri

android/build.gradle.kts

@@ -0,0 +1,40 @@
+plugins {
+    id("com.android.library")
+    id("org.jetbrains.kotlin.android")
+}
+
+android {
+    namespace = "org.silvermine.plugin.connectivity"
+    compileSdk = 36
+
+    defaultConfig {
+        minSdk = 23
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+        consumerProguardFiles("consumer-rules.pro")
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
+
+dependencies {
+    testImplementation("junit:junit:4.13.2")
+    androidTestImplementation("androidx.test.ext:junit:1.1.5")
+    androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
+    implementation(project(":tauri-android"))
+}

android/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

android/settings.gradle

@@ -0,0 +1,31 @@
+pluginManagement {
+    repositories {
+        mavenCentral()
+        gradlePluginPortal()
+        google()
+    }
+    resolutionStrategy {
+        eachPlugin {
+            switch (requested.id.id) {
+                case "com.android.library":
+                    useVersion("8.0.2")
+                    break
+                case "org.jetbrains.kotlin.android":
+                    useVersion("1.8.20")
+                    break
+            }
+        }
+    }
+}
+
+dependencyResolutionManagement {
+    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
+    repositories {
+        mavenCentral()
+        google()
+
+    }
+}
+
+include ':tauri-android'
+project(':tauri-android').projectDir = new File('./.tauri/tauri-api')

android/src/main/AndroidManifest.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+</manifest>

android/src/main/java/org/silvermine/plugin/connectivity/Connectivity.kt

@@ -0,0 +1,134 @@
+package org.silvermine.plugin.connectivity
+
+import android.content.Context
+import android.net.ConnectivityManager
+import android.net.NetworkCapabilities
+import android.os.Build
+import app.tauri.plugin.JSObject
+
+class Connectivity(context: Context) {
+   private val connectivityManager =
+      context.getSystemService(Context.CONNECTIVITY_SERVICE) as? ConnectivityManager
+
+   fun connectionStatus(): JSObject {
+      val manager = connectivityManager ?: return NativeConnectionStatus.disconnected().toJSObject()
+      val activeNetwork = manager.activeNetwork ?: return NativeConnectionStatus.disconnected().toJSObject()
+      val capabilities = manager.getNetworkCapabilities(activeNetwork)
+         ?: return NativeConnectionStatus.disconnected().toJSObject()
+
+      if (!AndroidConnectivityMapper.isConnected(
+            capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET),
+            capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)
+         )) {
+         return NativeConnectionStatus.disconnected().toJSObject()
+      }
+
+      // `TEMPORARILY_NOT_METERED` means the active network should be treated as
+      // effectively unmetered while Android exposes that capability.
+      val hasTemporarilyNotMetered = hasTemporarilyNotMetered(capabilities)
+      val status = NativeConnectionStatus(
+         connected = true,
+         metered = AndroidConnectivityMapper.isMetered(
+            capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_METERED),
+            hasTemporarilyNotMetered
+         ),
+         constrained = AndroidConnectivityMapper.isConstrained(isBackgroundRestricted(manager)),
+         connectionType = AndroidConnectivityMapper.connectionType(
+            capabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI),
+            capabilities.hasTransport(NetworkCapabilities.TRANSPORT_ETHERNET),
+            capabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR)
+         )
+      )
+
+      return status.toJSObject()
+   }
+
+   private fun isBackgroundRestricted(manager: ConnectivityManager): Boolean {
+      // Data Saver's restrict-background status was added after API 23.
+      if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) {
+         return false
+      }
+
+      return manager.restrictBackgroundStatus == ConnectivityManager.RESTRICT_BACKGROUND_STATUS_ENABLED
+   }
+
+   private fun hasTemporarilyNotMetered(capabilities: NetworkCapabilities): Boolean {
+      // Guard the API 30 capability so the plugin still supports API 23+.
+      if (Build.VERSION.SDK_INT < Build.VERSION_CODES.R) {
+         return false
+      }
+
+      return capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_TEMPORARILY_NOT_METERED)
+   }
+}
+
+data class NativeConnectionStatus(
+   val connected: Boolean,
+   val metered: Boolean,
+   val constrained: Boolean,
+   val connectionType: ConnectionType
+) {
+   fun toJSObject(): JSObject {
+      val status = JSObject()
+
+      status.put("connected", connected)
+      status.put("metered", metered)
+      status.put("constrained", constrained)
+      status.put("connectionType", connectionType.serializedName)
+
+      return status
+   }
+
+   companion object {
+      fun disconnected(): NativeConnectionStatus {
+         return NativeConnectionStatus(
+            connected = false,
+            metered = false,
+            constrained = false,
+            connectionType = ConnectionType.UNKNOWN
+         )
+      }
+   }
+}
+
+enum class ConnectionType(val serializedName: String) {
+   WIFI("wifi"),
+   ETHERNET("ethernet"),
+   CELLULAR("cellular"),
+   UNKNOWN("unknown")
+}
+
+object AndroidConnectivityMapper {
+   fun isConnected(hasInternet: Boolean, isValidated: Boolean): Boolean {
+      // `INTERNET` alone can include captive portals or unvalidated networks.
+      return hasInternet && isValidated
+   }
+
+   fun isMetered(hasNotMetered: Boolean, hasTemporarilyNotMetered: Boolean): Boolean {
+      return !hasNotMetered && !hasTemporarilyNotMetered
+   }
+
+   fun isConstrained(isBackgroundRestricted: Boolean): Boolean {
+      return isBackgroundRestricted
+   }
+
+   fun connectionType(
+      hasWifi: Boolean,
+      hasEthernet: Boolean,
+      hasCellular: Boolean
+   ): ConnectionType {
+      if (hasWifi) {
+         return ConnectionType.WIFI
+      }
+
+      if (hasEthernet) {
+         return ConnectionType.ETHERNET
+      }
+
+      if (hasCellular) {
+         return ConnectionType.CELLULAR
+      }
+
+      return ConnectionType.UNKNOWN
+   }
+}

android/src/main/java/org/silvermine/plugin/connectivity/ConnectivityPlugin.kt

@@ -0,0 +1,19 @@
+package org.silvermine.plugin.connectivity
+
+import android.app.Activity
+import app.tauri.annotation.Command
+import app.tauri.annotation.TauriPlugin
+import app.tauri.plugin.Invoke
+import app.tauri.plugin.Plugin
+
+// Android side of the Rust `register_android_plugin(..., "ConnectivityPlugin")`
+// bridge.
+@TauriPlugin
+class ConnectivityPlugin(activity: Activity) : Plugin(activity) {
+   private val connectivity = Connectivity(activity.applicationContext)
+
+   @Command
+   fun connectionStatus(invoke: Invoke) {
+      invoke.resolve(connectivity.connectionStatus())
+   }
+}