ui,tunnel: auto-detect IPv6/IPv4 preference

Detect IP address change.
Request non-VPN network.
Update endpoint when needed.
Unregister network on wgTurnOff and use IPv4 if network is not known.

1 files changed, 49 insertions, 3 deletions

diff --git a/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java b/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
index 242f81d8..19f328f2 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
@@ -7,6 +7,11 @@ package com.wireguard.android.backend;
 
 import android.content.Context;
 import android.content.Intent;
+import android.net.ConnectivityManager;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.NetworkCapabilities;
+import android.net.NetworkRequest;
 import android.net.ProxyInfo;
 import android.os.Build;
 import android.os.ParcelFileDescriptor;
@@ -23,6 +28,7 @@ import com.wireguard.config.Peer;
 import com.wireguard.crypto.Key;
 import com.wireguard.crypto.KeyFormatException;
 import com.wireguard.util.NonNullForAll;
+import com.wireguard.util.Resolver;
 
 import java.net.InetAddress;
 import java.net.URL;
@@ -52,6 +58,9 @@ public final class GoBackend implements Backend {
     @Nullable private Config currentConfig;
     @Nullable private Tunnel currentTunnel;
     private int currentTunnelHandle = -1;
+    private ConnectivityManager connectivityManager;
+    private ConnectivityManager.NetworkCallback myNetworkCallback = new MyNetworkCallback();
+    @Nullable private Network activeNetwork;
 
     /**
      * Public constructor for GoBackend.
@@ -61,6 +70,7 @@ public final class GoBackend implements Backend {
     public GoBackend(final Context context) {
         SharedLibraryLoader.loadSharedLibrary(context, "wg-go");
         this.context = context;
+        connectivityManager = context.getSystemService(ConnectivityManager.class);
     }
 
     /**
@@ -79,6 +89,8 @@ public final class GoBackend implements Backend {
 
     private static native int wgGetSocketV6(int handle);
 
+    private static native int wgSetConfig(int handle, String settings);
+
     private static native void wgTurnOff(int handle);
 
     private static native int wgTurnOn(String ifName, int tunFd, String settings);
@@ -258,13 +270,19 @@ public final class GoBackend implements Backend {
             }
 
 
+            activeNetwork = connectivityManager.getActiveNetwork();
+            if (!connectivityManager.getNetworkCapabilities(activeNetwork).hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN)) {
+                Log.w(TAG, "VPN network is active, null activeNetwork");
+                activeNetwork = null;
+            }
+            final Resolver resolver = new Resolver(activeNetwork, connectivityManager.getLinkProperties(activeNetwork));
             dnsRetry: for (int i = 0; i < DNS_RESOLUTION_RETRIES; ++i) {
                 // Pre-resolve IPs so they're cached when building the userspace string
                 for (final Peer peer : config.getPeers()) {
                     final InetEndpoint ep = peer.getEndpoint().orElse(null);
                     if (ep == null)
                         continue;
-                    if (ep.getResolved().orElse(null) == null) {
+                    if (ep.getResolved(resolver, true).orElse(null) == null) {
                         if (i < DNS_RESOLUTION_RETRIES - 1) {
                             Log.w(TAG, "DNS host \"" + ep.getHost() + "\" failed to resolve; trying again");
                             Thread.sleep(1000);
@@ -277,7 +295,7 @@ public final class GoBackend implements Backend {
             }
 
             // Build config
-            final String goConfig = config.toWgUserspaceString();
+            final String goConfig = config.toWgUserspaceString(resolver);
 
             // Create the vpn tunnel with android API
             final VpnService.Builder builder = service.getBuilder();
@@ -339,6 +357,9 @@ public final class GoBackend implements Backend {
 
             service.protect(wgGetSocketV4(currentTunnelHandle));
             service.protect(wgGetSocketV6(currentTunnelHandle));
+
+            NetworkRequest req = new NetworkRequest.Builder().addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN).build();
+            connectivityManager.requestNetwork(req,  myNetworkCallback);
         } else {
             if (currentTunnelHandle == -1) {
                 Log.w(TAG, "Tunnel already down");
@@ -348,6 +369,8 @@ public final class GoBackend implements Backend {
             currentTunnel = null;
             currentTunnelHandle = -1;
             currentConfig = null;
+            connectivityManager.unregisterNetworkCallback(myNetworkCallback);
+            activeNetwork = null;
             wgTurnOff(handleToClose);
             try {
                 vpnService.get(0, TimeUnit.NANOSECONDS).stopSelf();
@@ -415,8 +438,11 @@ public final class GoBackend implements Backend {
             if (owner != null) {
                 final Tunnel tunnel = owner.currentTunnel;
                 if (tunnel != null) {
-                    if (owner.currentTunnelHandle != -1)
+                    if (owner.currentTunnelHandle != -1) {
+                        owner.connectivityManager.unregisterNetworkCallback(owner.myNetworkCallback);
+                        owner.activeNetwork = null;
                         wgTurnOff(owner.currentTunnelHandle);
+                    }
                     owner.currentTunnel = null;
                     owner.currentTunnelHandle = -1;
                     owner.currentConfig = null;
@@ -442,4 +468,24 @@ public final class GoBackend implements Backend {
             this.owner = owner;
         }
     }
+
+    private class MyNetworkCallback extends ConnectivityManager.NetworkCallback {
+        @Override
+        public void onAvailable(Network network) {
+            activeNetwork = network;
+            Log.w(TAG, "onAvailable: " + activeNetwork);
+        }
+
+        @Override
+        public void onLinkPropertiesChanged(Network network, LinkProperties linkProperties) {
+            Log.w(TAG, "onLinkPropertiesChanged: " + network + " is default:" + (network.equals(activeNetwork)));
+            if (network.equals(activeNetwork) && currentConfig != null && currentTunnelHandle > -1) {
+                final Resolver resolver = new Resolver(network, linkProperties);
+                final String goConfig = currentConfig.toWgEndpointsUserspaceString(resolver);
+                Log.w(TAG, "is default network, config:" + goConfig);
+
+                wgSetConfig(currentTunnelHandle, goConfig);
+            }
+        }
+    }
 }