tunnel: renew DHCP leases

* Add valid and preferred lifetime to dhcp leases
* Delay renew until VPN network is available

3 files changed, 152 insertions, 23 deletions

diff --git a/tunnel/src/main/java/com/wireguard/android/backend/Dhcp.java b/tunnel/src/main/java/com/wireguard/android/backend/Dhcp.java
index 59a3e69c..41060ddf 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/Dhcp.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/Dhcp.java
@@ -8,6 +8,11 @@ package com.wireguard.android.backend;
 import com.wireguard.config.InetNetwork;
 import com.wireguard.util.NonNullForAll;
 
+import java.time.Duration;
+import java.time.Instant;
+import java.time.LocalTime;
+import java.time.ZoneId;
+import java.util.LinkedHashSet;
 import java.util.Set;
 
 /**
@@ -15,14 +20,44 @@ import java.util.Set;
  */
 @NonNullForAll
 public class Dhcp {
-    private Set<InetNetwork> addresses;
+    private Set<Lease> leases = new LinkedHashSet<>();
 
-    Dhcp(Set<InetNetwork> addresses) {
-        this.addresses = addresses;
+    public class Lease {
+        private InetNetwork address;
+        private Duration validLt;
+        private Duration preferredLt;
+        private Instant validTs;
+        private Instant preferredTs;
+
+        public Lease(InetNetwork address, Duration validLt, Duration preferredLt) {
+            this.address = address;
+            this.validLt = validLt;
+            this.preferredLt = preferredLt;
+
+            Instant now = Instant.now();
+            this.validTs = now.plus(validLt);
+            this.preferredTs = now.plus(preferredLt);
+        }
+
+        public final InetNetwork getAddress() {
+            return this.address;
+        }
+
+        public String toString() {
+            ZoneId zone = ZoneId.systemDefault();
+            LocalTime validLocal = validTs.atZone(zone).toLocalTime().withNano(0);
+            LocalTime preferredLocal = preferredTs.atZone(zone).toLocalTime().withNano(0);
+            // TODO add date when needed
+            return address.toString() + " (valid " + validLocal + ", preferred " + preferredLocal + ")";
+        }
+    }
+
+    public void addLease(InetNetwork address, Duration valid, Duration preferred) {
+        this.leases.add(new Lease(address, valid, preferred));
     }
 
-    public Set<InetNetwork> getAddresses() {
-        return addresses;
+    public final Set<Lease> getLeases() {
+        return leases;
     }
 
     public String toString() {
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 6bd42936..79b724e8 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
@@ -5,6 +5,7 @@
 
 package com.wireguard.android.backend;
 
+import android.app.AlarmManager;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.PackageManager;
@@ -18,8 +19,12 @@ import android.net.ProxyInfo;
 import android.net.TrafficStats;
 import android.net.Uri;
 import android.os.Build;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.Message;
 import android.os.ParcelFileDescriptor;
 import android.os.Process;
+import android.os.SystemClock;
 import android.system.OsConstants;
 import android.util.Log;
 
@@ -75,10 +80,10 @@ import java.net.Inet6Address;
 import java.net.InetSocketAddress;
 import java.net.UnknownHostException;
 import java.net.URL;
+import java.time.Duration;
 import java.time.Instant;
 import java.nio.ByteOrder;
 import java.util.Collections;
-import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
@@ -104,6 +109,7 @@ public final class GoBackend implements Backend {
     private static final int DNS_RESOLUTION_RETRIES = 10;
     private static final String TAG = "WireGuard/GoBackend";
     private static final int STATS_TAG = 2;
+    private static final int MSG_DHCP_EXPIRE = 1;
     @Nullable private static AlwaysOnCallback alwaysOnCallback;
     private static GhettoCompletableFuture<VpnService> vpnService = new GhettoCompletableFuture<>();
     private final Context context;
@@ -117,6 +123,8 @@ public final class GoBackend implements Backend {
     private ManagedChannel channel;
     private boolean obtainDhcpLease = false;
     @Nullable private Bgp bgp;
+    private HandlerThread thread;
+    private Handler handler;
 
     /**
      * Public constructor for GoBackend.
@@ -398,6 +406,10 @@ public final class GoBackend implements Backend {
     }
 
     private void Dhcp(VpnService service) throws Exception{
+        if (currentConfig == null || currentTunnel == null || currentTunnelHandle < 0) {
+            return;
+        }
+
         obtainDhcpLease = false;
 
         // Heuristics: Use first ULA address as client address
@@ -421,23 +433,27 @@ public final class GoBackend implements Backend {
         DhcpResponse resp = stub.dhcp(request);
         Log.i(TAG, "Dhcp: " + resp.getError().getMessage());
 
-        Set<InetNetwork> addresses = new LinkedHashSet<>();
+        Dhcp dhcp = new Dhcp();
+        long delayMillis = 1000 * 3600 * 12; // Max renew 12h
+
         if (resp.getLeasesList() != null) {
             for (final Lease lease: resp.getLeasesList()) {
                 try {
                     InetAddress addr = InetAddress.getByAddress(lease.getAddress().getAddress().toByteArray());
-                    Log.i(TAG, "Lease: " + addr);
-                    addresses.add(new InetNetwork(addr, 128));
+                    Log.i(TAG, "Lease: " + addr + " " + lease.getValidLifetime().getSeconds() + " " + lease.getPreferredLifetime().getSeconds());
+                    dhcp.addLease(new InetNetwork(addr, 128),
+                                  Duration.ofSeconds(lease.getValidLifetime().getSeconds(), lease.getValidLifetime().getNanos()),
+                                  Duration.ofSeconds(lease.getPreferredLifetime().getSeconds(), lease.getPreferredLifetime().getNanos()));
+                    long leaseDelayMillis = lease.getValidLifetime().getSeconds() * 1000 + lease.getValidLifetime().getNanos() / 1000;
+                    delayMillis = Math.min(delayMillis, leaseDelayMillis);
                 } catch (UnknownHostException ex) {
                     // Ignore
                 }
             }
         }
 
-        Dhcp dhcp = new Dhcp(addresses);
-
         // Replace the vpn tunnel
-        final VpnService.Builder builder = getBuilder(currentTunnel.getName(), currentConfig, service, dhcp.getAddresses());
+        final VpnService.Builder builder = getBuilder(currentTunnel.getName(), currentConfig, service, dhcp.getLeases());
 
         Log.i(TAG, "Builder: " + builder);
 
@@ -455,8 +471,14 @@ public final class GoBackend implements Backend {
         service.protect(wgGetSocketV6(currentTunnelHandle));
         Log.i(TAG, "Dhcp done");
 
-        bgp = new Bgp(this, channel, currentTunnel, currentTunnelHandle);
-        bgp.startServer();
+        AlarmManager am = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
+        am.cancel(alarmListener);
+        am.setWindow(AlarmManager.ELAPSED_REALTIME, SystemClock.elapsedRealtime() + delayMillis * 3 / 4, delayMillis / 4, null, alarmListener, handler);
+
+        if (bgp != null) {
+            bgp = new Bgp(this, channel, currentTunnel, currentTunnelHandle);
+            bgp.startServer();
+        }
 
         currentTunnel.onDhcpChange(dhcp);
     }
@@ -543,7 +565,7 @@ public final class GoBackend implements Backend {
         Log.i(TAG, "Exit streamReverse");
     }
 
-    private VpnService.Builder getBuilder(final String name, @Nullable final Config config, final VpnService service, @Nullable final Set<InetNetwork> leases) throws PackageManager.NameNotFoundException {
+    private VpnService.Builder getBuilder(final String name, @Nullable final Config config, final VpnService service, @Nullable final Set<Dhcp.Lease> leases) throws PackageManager.NameNotFoundException {
         Log.i(TAG, "Builder 1");
             final VpnService.Builder builder = service.getBuilder();
         Log.i(TAG, "Builder 2");
@@ -559,8 +581,9 @@ public final class GoBackend implements Backend {
 
         Log.i(TAG, "Builder 5");
             if (leases != null) {
-                for (final InetNetwork lease: leases) {
-                    builder.addAddress(lease.getAddress(), lease.getMask());
+                for (final Dhcp.Lease lease: leases) {
+                    InetNetwork addr = lease.getAddress();
+                    builder.addAddress(addr.getAddress(), addr.getMask());
                 }
             }
 
@@ -659,7 +682,11 @@ public final class GoBackend implements Backend {
 
 
             activeNetwork = connectivityManager.getActiveNetwork();
-            if (!connectivityManager.getNetworkCapabilities(activeNetwork).hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN)) {
+            if (activeNetwork == null) {
+                Log.w(TAG, "Null activeNetwork");
+                activeNetwork = null;
+            }
+            else if (!connectivityManager.getNetworkCapabilities(activeNetwork).hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN)) {
                 Log.w(TAG, "VPN network is active, null activeNetwork");
                 activeNetwork = null;
             }
@@ -708,6 +735,33 @@ public final class GoBackend implements Backend {
 
             obtainDhcpLease = true;
 
+            thread = new HandlerThread("GoBackend HandlerThread");
+            thread.start();
+            handler = new Handler(thread.getLooper()) {
+                    public void handleMessage(Message msg) {
+                        switch (msg.what) {
+                        case MSG_DHCP_EXPIRE:
+                            Log.w(TAG, "DHCP expire: " + ((activeNetwork != null) ? activeNetwork : "disabled"));
+                            try {
+                                if (activeNetwork != null) {
+                                    Log.w(TAG, "DHCP before");
+                                    Dhcp(service); // Renew addresses
+                                    Log.w(TAG, "DHCP after");
+                                } else {
+                                    Log.w(TAG, "DHCP delay obtain lease");
+                                    obtainDhcpLease = true;
+                                }
+                            } catch (Exception ex) {
+                                Log.e(TAG, "DHCP failed: " + ex);
+                            }
+                            break;
+                        default:
+                            Log.w(TAG, "Unknown message: " + msg.what);
+                            break;
+                        }
+                    }
+            };
+
             NetworkRequest req = new NetworkRequest.Builder().addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN).build();
             connectivityManager.requestNetwork(req,  myNetworkCallback);
 
@@ -723,6 +777,14 @@ public final class GoBackend implements Backend {
             currentTunnel = null;
             currentTunnelHandle = -1;
             currentConfig = null;
+
+            AlarmManager am = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
+            am.cancel(alarmListener);
+            if (thread != null) {
+                handler = null;
+                thread.quit();
+                thread = null;
+            }
             if (bgp != null) {
                 bgp.stopServer();
                 bgp = null;
@@ -802,6 +864,14 @@ public final class GoBackend implements Backend {
                     owner.bgp.stopServer();
                     owner.bgp = null;
                 }
+                AlarmManager am = (AlarmManager)owner.context.getSystemService(Context.ALARM_SERVICE);
+                am.cancel(owner.alarmListener);
+                if (owner.thread != null) {
+                    owner.handler = null;
+                    owner.thread.quit();
+                    owner.thread = null;
+                }
+
                 owner.stopHttpProxy();
                 final Tunnel tunnel = owner.currentTunnel;
                 if (tunnel != null) {
@@ -847,7 +917,7 @@ public final class GoBackend implements Backend {
         @Override
         public void onAvailable(Network network) {
             Log.w(TAG, "VPN onAvailable: " + network);
-            if (obtainDhcpLease) {
+            if (obtainDhcpLease && activeNetwork != null) {
                 Log.w(TAG, "Obtaindhcplease");
                 try {
                     Log.w(TAG, "Before Dhcp");
@@ -868,6 +938,20 @@ public final class GoBackend implements Backend {
         }
 
         @Override
+        public void onLosing(Network network, int maxMsToLive) {
+            Log.w(TAG, "onLosing: " + network + " maxMsToLive: " + maxMsToLive);
+            // TODO release DHCP?
+        }
+
+        @Override
+        public void onLost(Network network) {
+            Log.w(TAG, "onLost: " + network + " (" + activeNetwork + ")");
+            if (network.equals(activeNetwork)) {
+                activeNetwork = null;
+            }
+        }
+
+        @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) {
@@ -889,4 +973,13 @@ public final class GoBackend implements Backend {
             }
         }
     }
+
+    private AlarmManager.OnAlarmListener alarmListener = new AlarmManager.OnAlarmListener() {
+            @Override
+            public void onAlarm() {
+                if (handler != null) {
+                    handler.sendEmptyMessage(MSG_DHCP_EXPIRE);
+                }
+            }
+        };
 }
diff --git a/tunnel/tools/libwg-go/dhcp.go b/tunnel/tools/libwg-go/dhcp.go
index b7919151..4af5b0cb 100644
--- a/tunnel/tools/libwg-go/dhcp.go
+++ b/tunnel/tools/libwg-go/dhcp.go
@@ -12,6 +12,7 @@ import (
         "github.com/insomniacslk/dhcp/iana"
 
 	gen "golang.zx2c4.com/wireguard/android/gen"
+        "google.golang.org/protobuf/types/known/durationpb"
 )
 
 const (
@@ -131,13 +132,13 @@ func getAddressesFromReply(reply *dhcpv6.Message) []*gen.Lease{
                 ianaOpts := iana.Options.Get(dhcpv6.OptionIAAddr)
 
                 for _, opt := range ianaOpts {
-                        addr :=opt.(*dhcpv6.OptIAAddress).IPv6Addr
+                        addrOpt := opt.(*dhcpv6.OptIAAddress)
                         lease := &gen.Lease{
                                 Address: &gen.InetAddress{
-                                        Address: addr,
+                                        Address: addrOpt.IPv6Addr,
                                 },
-                                // PreferredLifetime: ,
-                                // ValidLifetime: ,
+                                PreferredLifetime: durationpb.New(addrOpt.PreferredLifetime),
+                                ValidLifetime: durationpb.New(addrOpt.ValidLifetime),
                         }
                         leases = append(leases, lease)
                 }