2 files changed, 67 insertions, 20 deletions

diff --git a/src/android/net/ip/IpClient.java b/src/android/net/ip/IpClient.java
index 08a9c5c..98e1e49 100644
--- a/src/android/net/ip/IpClient.java
+++ b/src/android/net/ip/IpClient.java
@@ -1289,13 +1289,13 @@ public class IpClient extends StateMachine {
             return;
         }
 
-        if (params.defaultMtu != mInterfaceParams.defaultMtu) {
-            try {
-                mNetd.interfaceSetMtu(mInterfaceName, mInterfaceParams.defaultMtu);
-            } catch (RemoteException | ServiceSpecificException e) {
-                logError("Couldn't reset MTU on " + mInterfaceName + " from "
-                        + params.defaultMtu + " to " + mInterfaceParams.defaultMtu, e);
-            }
+        if (params.defaultMtu == mInterfaceParams.defaultMtu) return;
+
+        try {
+            mNetd.interfaceSetMtu(mInterfaceName, mInterfaceParams.defaultMtu);
+        } catch (RemoteException | ServiceSpecificException e) {
+            logError("Couldn't reset MTU on " + mInterfaceName + " from "
+                    + params.defaultMtu + " to " + mInterfaceParams.defaultMtu, e);
         }
     }
 
diff --git a/tests/integration/src/android/net/ip/IpClientIntegrationTest.java b/tests/integration/src/android/net/ip/IpClientIntegrationTest.java
index 400bd51..cb7d418 100644
--- a/tests/integration/src/android/net/ip/IpClientIntegrationTest.java
+++ b/tests/integration/src/android/net/ip/IpClientIntegrationTest.java
@@ -50,6 +50,7 @@ import android.content.res.Resources;
 import android.net.ConnectivityManager;
 import android.net.INetd;
 import android.net.InetAddresses;
+import android.net.LinkProperties;
 import android.net.NetworkStackIpMemoryStore;
 import android.net.TestNetworkInterface;
 import android.net.TestNetworkManager;
@@ -69,6 +70,8 @@ import android.os.HandlerThread;
 import android.os.IBinder;
 import android.os.ParcelFileDescriptor;
 import android.os.RemoteException;
+import android.system.ErrnoException;
+import android.system.Os;
 
 import androidx.annotation.Nullable;
 import androidx.test.InstrumentationRegistry;
@@ -395,8 +398,8 @@ public class IpClientIntegrationTest {
         mDependencies.setDhcpRapidCommitEnabled(isDhcpRapidCommitEnabled);
         mIpc.setL2KeyAndGroupHint(TEST_L2KEY, TEST_GROUPHINT);
         mIpc.startProvisioning(config);
-        verify(mCb, times(1)).setNeighborDiscoveryOffload(true);
-        verify(mCb, timeout(TEST_TIMEOUT_MS).times(1)).setFallbackMulticastFilter(false);
+        verify(mCb).setNeighborDiscoveryOffload(true);
+        verify(mCb, timeout(TEST_TIMEOUT_MS)).setFallbackMulticastFilter(false);
         verify(mCb, never()).onProvisioningFailure(any());
     }
 
@@ -478,7 +481,22 @@ public class IpClientIntegrationTest {
         return getNextDhcpPacket();
     }
 
-    private void doRestoreInitialMtuTest(final boolean shouldChangeMtu) throws Exception {
+    private void removeTapInterface(final FileDescriptor fd) {
+        try {
+            Os.close(fd);
+        } catch (ErrnoException e) {
+            fail("Fail to close file descriptor: " + e);
+        }
+    }
+
+    private void verifyAfterIpClientShutdown() throws RemoteException {
+        final LinkProperties emptyLp = new LinkProperties();
+        emptyLp.setInterfaceName(mIfaceName);
+        verify(mCb, timeout(TEST_TIMEOUT_MS)).onLinkPropertiesChange(emptyLp);
+    }
+
+    private void doRestoreInitialMtuTest(final boolean shouldChangeMtu,
+            final boolean shouldRemoveTapInterface) throws Exception {
         final long currentTime = System.currentTimeMillis();
         int mtu = TEST_DEFAULT_MTU;
 
@@ -493,11 +511,21 @@ public class IpClientIntegrationTest {
             assertEquals(NetworkInterface.getByName(mIfaceName).getMTU(), mtu);
         }
 
-        mIpc.shutdown();
-        HandlerUtilsKt.waitForIdle(mIpc.getHandler(), TEST_TIMEOUT_MS);
-        // Verify that MTU indeed has been restored or not.
-        verify(mMockNetd, times(shouldChangeMtu ? 1 : 0)).interfaceSetMtu(mIfaceName,
-                TEST_DEFAULT_MTU);
+        if (shouldRemoveTapInterface) removeTapInterface(mPacketReader.createFd());
+        try {
+            mIpc.shutdown();
+            HandlerUtilsKt.waitForIdle(mIpc.getHandler(), TEST_TIMEOUT_MS);
+            if (shouldRemoveTapInterface) {
+                verify(mMockNetd, never()).interfaceSetMtu(mIfaceName, TEST_DEFAULT_MTU);
+            } else {
+                // Verify that MTU indeed has been restored or not.
+                verify(mMockNetd, times(shouldChangeMtu ? 1 : 0))
+                        .interfaceSetMtu(mIfaceName, TEST_DEFAULT_MTU);
+            }
+            verifyAfterIpClientShutdown();
+        } catch (Exception e) {
+            fail("Exception should not have been thrown after shutdown: " + e);
+        }
     }
 
     @Test
@@ -628,20 +656,39 @@ public class IpClientIntegrationTest {
 
     @Test
     public void testRestoreInitialInterfaceMtu() throws Exception {
-        doRestoreInitialMtuTest(true /* shouldChangeMtu */);
+        doRestoreInitialMtuTest(true /* shouldChangeMtu */, false /* shouldRemoveTapInterface */);
     }
 
     @Test
-    public void testRestoreInitialInterfaceMtuWithoutChange() throws Exception {
-        doRestoreInitialMtuTest(false /* shouldChangeMtu */);
+    public void testRestoreInitialInterfaceMtu_WithoutMtuChange() throws Exception {
+        doRestoreInitialMtuTest(false /* shouldChangeMtu */, false /* shouldRemoveTapInterface */);
     }
 
     @Test
-    public void testRestoreInitialInterfaceMtuWithException() throws Exception {
+    public void testRestoreInitialInterfaceMtu_WithException() throws Exception {
         doThrow(new RemoteException("NetdNativeService::interfaceSetMtu")).when(mMockNetd)
                 .interfaceSetMtu(mIfaceName, TEST_DEFAULT_MTU);
 
-        doRestoreInitialMtuTest(true /* shouldChangeMtu */);
+        doRestoreInitialMtuTest(true /* shouldChangeMtu */, false /* shouldRemoveTapInterface */);
         assertEquals(NetworkInterface.getByName(mIfaceName).getMTU(), TEST_MIN_MTU);
     }
+
+    @Test
+    public void testRestoreInitialInterfaceMtu_NotFoundInterfaceWhenStopping() throws Exception {
+        doRestoreInitialMtuTest(true /* shouldChangeMtu */, true /* shouldRemoveTapInterface */);
+    }
+
+    @Test
+    public void testRestoreInitialInterfaceMtu_NotFoundInterfaceWhenStartingProvisioning()
+            throws Exception {
+        removeTapInterface(mPacketReader.createFd());
+        ProvisioningConfiguration config = new ProvisioningConfiguration.Builder()
+                .withoutIpReachabilityMonitor()
+                .withoutIPv6()
+                .build();
+
+        mIpc.startProvisioning(config);
+        verify(mCb).onProvisioningFailure(any());
+        verify(mCb, never()).setNeighborDiscoveryOffload(true);
+    }
 }