Configure one mobile VPN from running TUN instances

Use admitted native members to configure VpnService and attach its
single fd to the core shared TUN. Wait for attachment completion and
record the actual attached members before refreshing VPN state. Report
rejected members in the GUI and preserve the VPN for unchanged healthy
members.

Reconcile ordinary configuration notifications without invalidating an
arbitrary member. Invalidate attachments on instance lifecycle changes,
including restarts that reuse an instance ID. Forward public IPv6
changes alongside proxy route changes to refresh the platform VPN
configuration.

Exclude confirmed IPv4-less members from readiness gating while
retaining retries for unavailable status and pending addresses. Quick
Settings stops all running TUN members and restores that group on the
next start, skipping removed configurations and no_tun networks.

Keep the FFI set_tun_fd call scoped to one instance and report
attachment errors. Cover mobile configuration, member rejection and
replacement, attachment completion, collection notifications, IPv4-less
members, and tile stop/start restoration in GUI regression tests.

Validate with 36 mobile VPN tests, vue-tsc --noEmit, Android GUI cargo
check, workspace clippy, and shared TUN network namespace tests.

tauri-plugin-vpnservice/android/src/main/java/TauriVpnService.kt

@@ -10,6 +10,7 @@ import android.os.ParcelFileDescriptor
 import android.os.Bundle
 import android.content.pm.ServiceInfo
 import androidx.core.app.NotificationCompat
+import android.system.OsConstants.AF_INET6
 import java.net.InetAddress
 import java.util.Arrays
 
@@ -20,10 +21,12 @@ class TauriVpnService : VpnService() {
         @JvmField var triggerCallback: (String, JSObject) -> Unit = { _, _ -> }
         @JvmField var self: TauriVpnService? = null
         @JvmField var ipv4Addr: String? = null
+        @JvmField var ipv4Addrs: Array<String> = emptyArray()
         @JvmField var routes: Array<String> = emptyArray()
         @JvmField var dns: String? = null
 
         const val IPV4_ADDR = "IPV4_ADDR"
+        const val IPV4_ADDRS = "IPV4_ADDRS"
         const val ROUTES = "ROUTES"
         const val DNS = "DNS"
         const val DISALLOWED_APPLICATIONS = "DISALLOWED_APPLICATIONS"
@@ -39,7 +42,8 @@ class TauriVpnService : VpnService() {
         println("vpn on start command ${intent?.getExtras()} $intent")
         startVpnForegroundService()
         var args = intent?.getExtras()
-        ipv4Addr = args?.getString(IPV4_ADDR)
+        ipv4Addrs = getIpv4Addrs(args)
+        ipv4Addr = ipv4Addrs.firstOrNull()
         routes = args?.getStringArray(ROUTES) ?: emptyArray()
         dns = args?.getString(DNS)
 
@@ -90,6 +94,7 @@ class TauriVpnService : VpnService() {
 
     private fun clearStatus() {
         ipv4Addr = null
+        ipv4Addrs = emptyArray()
         routes = emptyArray()
         dns = null
     }
@@ -159,25 +164,40 @@ class TauriVpnService : VpnService() {
         }
     }
 
+    private fun getIpv4Addrs(args: Bundle?): Array<String> {
+        val ipv4Addrs = args
+            ?.getStringArray(IPV4_ADDRS)
+            ?.filter { it.isNotBlank() }
+            ?.toTypedArray()
+            ?: emptyArray()
+        if (ipv4Addrs.isNotEmpty()) {
+            return ipv4Addrs
+        }
+
+        return arrayOf(args?.getString(IPV4_ADDR) ?: "10.126.126.1/24")
+    }
+
     private fun createVpnInterface(args: Bundle?): ParcelFileDescriptor {
         var builder = Builder()
                 .setSession("TauriVpnService")
                 .setBlocking(false)
         
         var mtu = args?.getInt(MTU) ?: 1500
-        var ipv4Addr = args?.getString(IPV4_ADDR) ?: "10.126.126.1/24"
+        var ipv4Addrs = getIpv4Addrs(args)
         var dns: String? = args?.getString(DNS)
         var routes = args?.getStringArray(ROUTES) ?: emptyArray()
         var disallowedApplications = args?.getStringArray(DISALLOWED_APPLICATIONS) ?: emptyArray()
 
-        println("vpn create vpn interface. mtu: $mtu, ipv4Addr: $ipv4Addr, dns:" +
+        println("vpn create vpn interface. mtu: $mtu, ipv4Addrs: ${java.util.Arrays.toString(ipv4Addrs)}, dns:" +
             "$dns, routes: ${java.util.Arrays.toString(routes)}," +
             "disallowedApplications:  ${java.util.Arrays.toString(disallowedApplications)}")
 
-        val ipParts = ipv4Addr.split("/")
-        if (ipParts.size != 2) throw IllegalArgumentException("Invalid IP addr string")
-        builder.addAddress(ipParts[0], ipParts[1].toInt())
-        builder.addAddress("fd00::1", 128)
+        for (ipv4Addr in ipv4Addrs) {
+            val ipParts = ipv4Addr.split("/")
+            if (ipParts.size != 2) throw IllegalArgumentException("Invalid IP addr string")
+            builder.addAddress(ipParts[0], ipParts[1].toInt())
+        }
+        builder.allowFamily(AF_INET6)
 
         builder.setMtu(mtu)
         dns?.let { builder.addDnsServer(it) }