Retry networkAddInterface on EBUSY errorCode am: 9163b2a5

package android.net.shared;

import static android.net.RouteInfo.RTN_UNICAST;

import static android.system.OsConstants.EBUSY;

import android.net.INetd;

import android.net.IpPrefix;

import android.net.TetherConfigParcel;

import android.os.RemoteException;

import android.os.ServiceSpecificException;

import android.os.SystemClock;

import android.util.Log;

import java.util.ArrayList;

import java.util.List;

 * @hide

 */

public class NetdUtils {

    private static final String TAG = NetdUtils.class.getSimpleName();

    /** Start tethering. */

    public static void tetherStart(final INetd netd, final boolean usingLegacyDnsProxy,

            final String[] dhcpRange) throws RemoteException, ServiceSpecificException {

    /** Setup interface for tethering. */

    public static void tetherInterface(final INetd netd, final String iface, final IpPrefix dest)

            throws RemoteException, ServiceSpecificException {

        netd.tetherInterfaceAdd(iface);

        tetherInterface(netd, iface, dest, 20 /* maxAttempts */, 50 /* pollingIntervalMs */);

    }

        netd.networkAddInterface(INetd.LOCAL_NET_ID, iface);

    /** Setup interface with configurable retries for tethering. */

    public static void tetherInterface(final INetd netd, final String iface, final IpPrefix dest,

            int maxAttempts, int pollingIntervalMs)

            throws RemoteException, ServiceSpecificException {

        netd.tetherInterfaceAdd(iface);

        networkAddInterface(netd, iface, maxAttempts, pollingIntervalMs);

        List<RouteInfo> routes = new ArrayList<>();

        routes.add(new RouteInfo(dest, null, iface, RTN_UNICAST));

        RouteUtils.addRoutesToLocalNetwork(netd, iface, routes);

    }

    /**

     * Retry Netd#networkAddInterface for EBUSY error code.

     * If the same interface (e.g., wlan0) is in client mode and then switches to tethered mode.

     * There can be a race where puts the interface into the local network but interface is still

     * in use in netd because the ConnectivityService thread hasn't processed the disconnect yet.

     * See b/158269544 for detail.

     */

    private static void networkAddInterface(final INetd netd, final String iface,

            int maxAttempts, int pollingIntervalMs)

            throws ServiceSpecificException, RemoteException {

        for (int i = 1; i <= maxAttempts; i++) {

            try {

                netd.networkAddInterface(INetd.LOCAL_NET_ID, iface);

                return;

            } catch (ServiceSpecificException e) {

                if (e.errorCode == EBUSY && i < maxAttempts) {

                    SystemClock.sleep(pollingIntervalMs);

                    continue;

                }

                Log.e(TAG, "Retry Netd#networkAddInterface failure: " + e);

                throw e;

            }

        }

    }

    /** Reset interface for tethering. */

    public static void untetherInterface(final INetd netd, String iface)

            throws RemoteException, ServiceSpecificException {

/*

 * Copyright (C) 2016 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package android.net.shared;

import static android.net.INetd.LOCAL_NET_ID;

import static android.system.OsConstants.EBUSY;

import static org.junit.Assert.assertEquals;

import static org.junit.Assert.fail;

import static org.mockito.Matchers.any;

import static org.mockito.Matchers.anyInt;

import static org.mockito.Matchers.anyString;

import static org.mockito.Matchers.eq;

import static org.mockito.Mockito.doAnswer;

import static org.mockito.Mockito.never;

import static org.mockito.Mockito.reset;

import static org.mockito.Mockito.times;

import static org.mockito.Mockito.verify;

import static org.mockito.Mockito.verifyNoMoreInteractions;

import android.net.INetd;

import android.net.IpPrefix;

import android.os.RemoteException;

import android.os.ServiceSpecificException;

import androidx.test.filters.SmallTest;

import androidx.test.runner.AndroidJUnit4;

import org.junit.Before;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.mockito.Mock;

import org.mockito.MockitoAnnotations;

@RunWith(AndroidJUnit4.class)

@SmallTest

public final class NetdUtilsTest {

    private static final String IFACE_NAME = "testnet1";

    private static final IpPrefix TEST_IPPREFIX = new IpPrefix("192.168.42.1/24");

    @Mock private INetd mNetd;

    @Before public void setUp() throws Exception {

        MockitoAnnotations.initMocks(this);

    }

    private void setNetworkAddInterfaceOutcome(final Exception cause, int numLoops)

            throws Exception {

        // This cannot be an int because local variables referenced from a lambda expression must

        // be final or effectively final.

        final Counter myCounter = new Counter();

        doAnswer((invocation) -> {

            myCounter.count();

            if (myCounter.isCounterReached(numLoops)) {

                if (cause == null) return null;

                throw cause;

            }

            throw new ServiceSpecificException(EBUSY);

        }).when(mNetd).networkAddInterface(LOCAL_NET_ID, IFACE_NAME);

    }

    class Counter {

        private int mValue = 0;

        private void count() {

            mValue++;

        }

        private boolean isCounterReached(int target) {

            return mValue >= target;

        }

    }

    private void verifyTetherInterfaceSucceeds(int expectedTries) throws Exception {

        setNetworkAddInterfaceOutcome(null, expectedTries);

        NetdUtils.tetherInterface(mNetd, IFACE_NAME, TEST_IPPREFIX);

        verify(mNetd).tetherInterfaceAdd(IFACE_NAME);

        verify(mNetd, times(expectedTries)).networkAddInterface(LOCAL_NET_ID, IFACE_NAME);

        verify(mNetd, times(2)).networkAddRoute(eq(LOCAL_NET_ID), eq(IFACE_NAME), any(), any());

        verifyNoMoreInteractions(mNetd);

        reset(mNetd);

    }

    @Test

    public void testTetherInterfaceSuccessful() throws Exception {

        // Expect #networkAddInterface successful at first tries.

        verifyTetherInterfaceSucceeds(1);

        // Expect #networkAddInterface successful after 10 tries.

        verifyTetherInterfaceSucceeds(10);

    }

    private void runTetherInterfaceWithServiceSpecificException(int expectedTries,

            int expectedCode) throws Exception {

        setNetworkAddInterfaceOutcome(new ServiceSpecificException(expectedCode), expectedTries);

        try {

            NetdUtils.tetherInterface(mNetd, IFACE_NAME, TEST_IPPREFIX, 20, 0);

            fail("Expect throw ServiceSpecificException");

        } catch (ServiceSpecificException e) {

            assertEquals(e.errorCode, expectedCode);

        }

        verifyNetworkAddInterfaceFails(expectedTries);

        reset(mNetd);

    }

    private void runTetherInterfaceWithRemoteException(int expectedTries) throws Exception {

        setNetworkAddInterfaceOutcome(new RemoteException(), expectedTries);

        try {

            NetdUtils.tetherInterface(mNetd, IFACE_NAME, TEST_IPPREFIX, 20, 0);

            fail("Expect throw RemoteException");

        } catch (RemoteException e) { }

        verifyNetworkAddInterfaceFails(expectedTries);

        reset(mNetd);

    }

    private void verifyNetworkAddInterfaceFails(int expectedTries) throws Exception {

        verify(mNetd).tetherInterfaceAdd(IFACE_NAME);

        verify(mNetd, times(expectedTries)).networkAddInterface(LOCAL_NET_ID, IFACE_NAME);

        verify(mNetd, never()).networkAddRoute(anyInt(), anyString(), any(), any());

        verifyNoMoreInteractions(mNetd);

    }

    @Test

    public void testTetherInterfaceFailOnNetworkAddInterface() throws Exception {

        // Test throwing ServiceSpecificException with EBUSY failure.

        runTetherInterfaceWithServiceSpecificException(20, EBUSY);

        // Test throwing ServiceSpecificException with unexpectedError.

        final int unexpectedError = 999;

        runTetherInterfaceWithServiceSpecificException(1, unexpectedError);

        // Test throwing ServiceSpecificException with unexpectedError after 7 tries.

        runTetherInterfaceWithServiceSpecificException(7, unexpectedError);

        // Test throwing RemoteException.

        runTetherInterfaceWithRemoteException(1);

        // Test throwing RemoteException after 3 tries.

        runTetherInterfaceWithRemoteException(3);

    }

}