From b42b8d0502da83f0c199f6efe818d1619fb9f70c Mon Sep 17 00:00:00 2001
From: Mikael Magnusson <mikma@users.sourceforge.net>
Date: Mon, 19 Jun 2023 22:07:07 +0200
Subject: WIP: Delay DHCP renew until VPN network available

---
 .../com/wireguard/android/backend/GoBackend.java   | 42 +++++++++++++++++-----
 1 file changed, 33 insertions(+), 9 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 11928d46..79b724e8 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
@@ -434,6 +434,7 @@ public final class GoBackend implements Backend {
         Log.i(TAG, "Dhcp: " + resp.getError().getMessage());
 
         Dhcp dhcp = new Dhcp();
+        long delayMillis = 1000 * 3600 * 12; // Max renew 12h
 
         if (resp.getLeasesList() != null) {
             for (final Lease lease: resp.getLeasesList()) {
@@ -443,6 +444,8 @@ public final class GoBackend implements Backend {
                     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
                 }
@@ -468,11 +471,8 @@ public final class GoBackend implements Backend {
         service.protect(wgGetSocketV6(currentTunnelHandle));
         Log.i(TAG, "Dhcp done");
 
-        // TODO fetch expiration time from Dhcp leases
-        long delayMillis = 1000 * 3600 * 12; // Renew 3/4 * 12h
-        //long delayMillis = lease.getValidLifetime().getSeconds() * 1000 + lease.getValidLifetime().getNanos() / 1000;
-
         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) {
@@ -682,7 +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;
             }
@@ -737,10 +741,16 @@ public final class GoBackend implements Backend {
                     public void handleMessage(Message msg) {
                         switch (msg.what) {
                         case MSG_DHCP_EXPIRE:
+                            Log.w(TAG, "DHCP expire: " + ((activeNetwork != null) ? activeNetwork : "disabled"));
                             try {
-                                Log.w(TAG, "Before Dhcp");
-                                Dhcp(service); // Renew addresses
-                                Log.w(TAG, "After Dhcp");
+                                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);
                             }
@@ -907,7 +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");
@@ -927,6 +937,20 @@ public final class GoBackend implements Backend {
             Log.w(TAG, "onAvailable: " + activeNetwork);
         }
 
+        @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)));
-- 
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