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Commit 98ed3325 authored by Xiao Ma's avatar Xiao Ma
Browse files

Restore the default interface MTU when disconnecting from Wi-Fi AP. 

Bug: 113350007
Test: atest FrameworksNetTests NetworkStackTests
Test: atest NetworkStackIntegrationTests
Test: manual test
Change-Id: I4b0ecdb63df567f0cbbb13d2b48bbfaaa7aee4d9
parent 03886222

src/android/net/ip/IpClient.java

+36 −3
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ package android.net.ip; 
import static android.net.RouteInfo.RTN_UNICAST;

import static android.net.shared.IpConfigurationParcelableUtil.toStableParcelable;



import static com.android.server.util.NetworkStackConstants.ETHER_MTU;

import static com.android.server.util.PermissionUtil.checkNetworkStackCallingPermission;



import android.annotation.NonNull;
@@ -48,6 +49,7 @@ import android.os.ConditionVariable; 
import android.os.IBinder;

import android.os.Message;

import android.os.RemoteException;

import android.os.ServiceSpecificException;

import android.os.SystemClock;

import android.text.TextUtils;

import android.util.LocalLog;
@@ -69,6 +71,8 @@ import com.android.server.NetworkStackService.NetworkStackServiceManager; 
import java.io.FileDescriptor;

import java.io.PrintWriter;

import java.net.InetAddress;

import java.net.NetworkInterface;

import java.net.SocketException;

import java.util.Collection;

import java.util.List;

import java.util.Objects;
@@ -380,6 +384,8 @@ public class IpClient extends StateMachine { 
    private final ConditionVariable mApfDataSnapshotComplete = new ConditionVariable();



    public static class Dependencies {

        private static final String TAG = "IpClient.Dependencies";



        /**

         * Get interface parameters for the specified interface.

         */
@@ -387,6 +393,18 @@ public class IpClient extends StateMachine { 
            return InterfaceParams.getByName(ifname);

        }



        /**

         * Get the current MTU for the specified interface.

         */

        public int getInterfaceMtu(String ifname) {

            try {

                return NetworkInterface.getByName(ifname).getMTU();

            } catch (SocketException e) {

                Log.e(TAG, "unexpected failure to get the interface MTU");

                return ETHER_MTU;

            }

        }



        /**

         * Get a INetd connector.

         */
@@ -850,10 +868,14 @@ public class IpClient extends StateMachine { 
        return shouldLog;

    }



    private void logError(String fmt, Object... args) {

    private void logError(String fmt, Throwable e, Object... args) {

        final String msg = "ERROR " + String.format(fmt, args);

        Log.e(mTag, msg);

        mLog.log(msg);

        Log.e(mTag, msg, e);

        mLog.e(msg, e);

    }



    private void logError(String fmt, Object... args) {

        logError(fmt, null, args);

    }



    // This needs to be called with care to ensure that our LinkProperties
@@ -1351,6 +1373,17 @@ public class IpClient extends StateMachine { 
                // There's no DHCPv4 for which to wait; proceed to stopped.

                deferMessage(obtainMessage(CMD_JUMP_STOPPING_TO_STOPPED));

            }



            // Restore the interface MTU to initial value if it has changed.

            final int mtu = mDependencies.getInterfaceMtu(mInterfaceName);

            try {

                if (mtu != mInterfaceParams.defaultMtu) {

                    mNetd.interfaceSetMtu(mInterfaceName, mInterfaceParams.defaultMtu);

                }

            } catch (RemoteException | ServiceSpecificException e) {

                logError("Couldn't reset MTU from "

                        + mtu + " to " + mInterfaceParams.defaultMtu + ": " + e);

            }

        }



        @Override

src/com/android/server/util/NetworkStackConstants.java

+2 −0
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ public final class NetworkStackConstants { 
    public static final int ETHER_TYPE_IPV4 = 0x0800;

    public static final int ETHER_TYPE_IPV6 = 0x86dd;

    public static final int ETHER_HEADER_LEN = 14;

    public static final int ETHER_MTU = 1500;



    /**

     * ARP constants.
@@ -97,6 +98,7 @@ public final class NetworkStackConstants { 
    public static final int IPV6_PROTOCOL_OFFSET = 6;

    public static final int IPV6_SRC_ADDR_OFFSET = 8;

    public static final int IPV6_DST_ADDR_OFFSET = 24;

    public static final int IPV6_MIN_MTU = 1280;



    /**

     * ICMPv6 constants.

tests/integration/Android.bp

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ android_test { 
        "androidx.annotation_annotation",

        "androidx.test.rules",

        "mockito-target-extended-minus-junit4",

        "net-tests-utils",

        "NetworkStackBase",

        "testables",

    ],

tests/integration/src/android/net/ip/IpClientIntegrationTest.java

+52 −18
Original line number Diff line number Diff line
@@ -77,6 +77,7 @@ import androidx.test.runner.AndroidJUnit4; 
import com.android.server.NetworkObserverRegistry;

import com.android.server.NetworkStackService.NetworkStackServiceManager;

import com.android.server.connectivity.ipmemorystore.IpMemoryStoreService;

import com.android.testutils.HandlerUtilsKt;



import org.junit.After;

import org.junit.Before;
@@ -158,7 +159,8 @@ public class IpClientIntegrationTest { 
    private static final Inet4Address BROADCAST_ADDR = getBroadcastAddress(

            SERVER_ADDR, PREFIX_LENGTH);

    private static final String HOSTNAME = "testhostname";

    private static final short MTU = 1500;

    private static final int TEST_DEFAULT_MTU = 1500;

    private static final int TEST_MIN_MTU = 1280;



    private static class TapPacketReader extends PacketReader {

        private final ParcelFileDescriptor mTapFd;
@@ -203,6 +205,7 @@ public class IpClientIntegrationTest { 
    private class Dependencies extends IpClient.Dependencies {

        private boolean mIsDhcpLeaseCacheEnabled;

        private boolean mIsDhcpRapidCommitEnabled;

        private int mMtu = TEST_DEFAULT_MTU;



        public void setDhcpLeaseCacheEnabled(final boolean enable) {

            mIsDhcpLeaseCacheEnabled = enable;
@@ -212,6 +215,10 @@ public class IpClientIntegrationTest { 
            mIsDhcpRapidCommitEnabled = enable;

        }



        public void setMtu(final int mtu) {

            mMtu = mtu;

        }



        @Override

        public INetd getNetd(Context context) {

            return mNetd;
@@ -242,6 +249,11 @@ public class IpClientIntegrationTest { 
                }

            };

        }



        @Override

        public int getInterfaceMtu(String ifName) {

            return mMtu;

        }

    }



    @Before
@@ -345,7 +357,7 @@ public class IpClientIntegrationTest { 
    }



    private static ByteBuffer buildDhcpOfferPacket(final DhcpPacket packet,

            final Integer leaseTimeSec) {

            final Integer leaseTimeSec, final short mtu) {

        return DhcpPacket.buildOfferPacket(DhcpPacket.ENCAP_L2, packet.getTransactionId(),

                false /* broadcast */, SERVER_ADDR, INADDR_ANY /* relayIp */,

                CLIENT_ADDR /* yourIp */, packet.getClientMac(), leaseTimeSec,
@@ -353,11 +365,11 @@ public class IpClientIntegrationTest { 
                Collections.singletonList(SERVER_ADDR) /* gateways */,

                Collections.singletonList(SERVER_ADDR) /* dnsServers */,

                SERVER_ADDR /* dhcpServerIdentifier */, null /* domainName */, HOSTNAME,

                false /* metered */, MTU);

                false /* metered */, mtu);

    }



    private static ByteBuffer buildDhcpAckPacket(final DhcpPacket packet,

            final Integer leaseTimeSec) {

            final Integer leaseTimeSec, final short mtu) {

        return DhcpPacket.buildAckPacket(DhcpPacket.ENCAP_L2, packet.getTransactionId(),

                false /* broadcast */, SERVER_ADDR, INADDR_ANY /* relayIp */,

                CLIENT_ADDR /* yourIp */, CLIENT_ADDR /* requestIp */, packet.getClientMac(),
@@ -365,7 +377,7 @@ public class IpClientIntegrationTest { 
                Collections.singletonList(SERVER_ADDR) /* gateways */,

                Collections.singletonList(SERVER_ADDR) /* dnsServers */,

                SERVER_ADDR /* dhcpServerIdentifier */, null /* domainName */, HOSTNAME,

                false /* metered */, MTU);

                false /* metered */, mtu);

    }



    private static ByteBuffer buildDhcpNakPacket(final DhcpPacket packet) {
@@ -397,7 +409,7 @@ public class IpClientIntegrationTest { 
    }



    private void assertIpMemoryStoreNetworkAttributes(final Integer leaseTimeSec,

            final long startTime) {

            final long startTime, final int mtu) {

        final ArgumentCaptor<NetworkAttributes> networkAttributes =

                ArgumentCaptor.forClass(NetworkAttributes.class);
@@ -416,7 +428,7 @@ public class IpClientIntegrationTest { 
            assertTrue(lowerBound < expiry);

        }

        assertEquals(Collections.singletonList(SERVER_ADDR), naValueCaptured.dnsAddresses);

        assertEquals(new Integer((int) MTU), naValueCaptured.mtu);

        assertEquals(new Integer(mtu), naValueCaptured.mtu);

    }



    private void assertIpMemoryNeverStoreNetworkAttributes() {
@@ -433,13 +445,16 @@ public class IpClientIntegrationTest { 
        while ((packet = getNextDhcpPacket()) != null) {

            if (packet instanceof DhcpDiscoverPacket) {

                if (isDhcpRapidCommitEnabled) {

                    sendResponse(buildDhcpAckPacket(packet, leaseTimeSec));

                    sendResponse(buildDhcpAckPacket(packet, leaseTimeSec,

                            (short) mDependencies.getInterfaceMtu(mIfaceName)));

                } else {

                    sendResponse(buildDhcpOfferPacket(packet, leaseTimeSec));

                    sendResponse(buildDhcpOfferPacket(packet, leaseTimeSec,

                            (short) mDependencies.getInterfaceMtu(mIfaceName)));

                }

            } else if (packet instanceof DhcpRequestPacket) {

                final ByteBuffer byteBuffer = isSuccessLease

                        ? buildDhcpAckPacket(packet, leaseTimeSec)

                        ? buildDhcpAckPacket(packet, leaseTimeSec,

                                (short) mDependencies.getInterfaceMtu(mIfaceName))

                        : buildDhcpNakPacket(packet);

                sendResponse(byteBuffer);

            } else {
@@ -487,7 +502,7 @@ public class IpClientIntegrationTest { 
        final long currentTime = System.currentTimeMillis();

        performDhcpHandshake(true /* isSuccessLease */, TEST_LEASE_DURATION_S,

                true /* isDhcpLeaseCacheEnabled */, false /* isDhcpRapidCommitEnabled */);

        assertIpMemoryStoreNetworkAttributes(TEST_LEASE_DURATION_S, currentTime);

        assertIpMemoryStoreNetworkAttributes(TEST_LEASE_DURATION_S, currentTime, TEST_DEFAULT_MTU);

    }



    @Test
@@ -502,7 +517,7 @@ public class IpClientIntegrationTest { 
        final long currentTime = System.currentTimeMillis();

        performDhcpHandshake(true /* isSuccessLease */, INFINITE_LEASE,

                true /* isDhcpLeaseCacheEnabled */, false /* isDhcpRapidCommitEnabled */);

        assertIpMemoryStoreNetworkAttributes(INFINITE_LEASE, currentTime);

        assertIpMemoryStoreNetworkAttributes(INFINITE_LEASE, currentTime, TEST_DEFAULT_MTU);

    }



    @Test
@@ -510,7 +525,7 @@ public class IpClientIntegrationTest { 
        final long currentTime = System.currentTimeMillis();

        performDhcpHandshake(true /* isSuccessLease */, null /* no lease time */,

                true /* isDhcpLeaseCacheEnabled */, false /* isDhcpRapidCommitEnabled */);

        assertIpMemoryStoreNetworkAttributes(null, currentTime);

        assertIpMemoryStoreNetworkAttributes(null, currentTime, TEST_DEFAULT_MTU);

    }



    @Test
@@ -527,7 +542,7 @@ public class IpClientIntegrationTest { 
        final long currentTime = System.currentTimeMillis();

        performDhcpHandshake(true /* isSuccessLease */, TEST_LEASE_DURATION_S,

                true /* isDhcpLeaseCacheEnabled */, true /* isDhcpRapidCommitEnabled */);

        assertIpMemoryStoreNetworkAttributes(TEST_LEASE_DURATION_S, currentTime);

        assertIpMemoryStoreNetworkAttributes(TEST_LEASE_DURATION_S, currentTime, TEST_DEFAULT_MTU);

    }



    @Test
@@ -536,7 +551,7 @@ public class IpClientIntegrationTest { 
                new NetworkAttributes.Builder()

                    .setAssignedV4Address(CLIENT_ADDR)

                    .setAssignedV4AddressExpiry(Long.MAX_VALUE) // lease is always valid

                    .setMtu(new Integer(MTU))

                    .setMtu(new Integer(TEST_DEFAULT_MTU))

                    .setGroupHint(TEST_GROUPHINT)

                    .setDnsAddresses(Collections.singletonList(SERVER_ADDR))

                    .build(), false /* timeout */);
@@ -549,7 +564,7 @@ public class IpClientIntegrationTest { 
                 new NetworkAttributes.Builder()

                    .setAssignedV4Address(CLIENT_ADDR)

                    .setAssignedV4AddressExpiry(EXPIRED_LEASE)

                    .setMtu(new Integer(MTU))

                    .setMtu(new Integer(TEST_DEFAULT_MTU))

                    .setGroupHint(TEST_GROUPHINT)

                    .setDnsAddresses(Collections.singletonList(SERVER_ADDR))

                    .build(), false /* timeout */);
@@ -568,7 +583,7 @@ public class IpClientIntegrationTest { 
                new NetworkAttributes.Builder()

                    .setAssignedV4Address(CLIENT_ADDR)

                    .setAssignedV4AddressExpiry(System.currentTimeMillis() + 3_600_000)

                    .setMtu(new Integer(MTU))

                    .setMtu(new Integer(TEST_DEFAULT_MTU))

                    .setGroupHint(TEST_GROUPHINT)

                    .setDnsAddresses(Collections.singletonList(SERVER_ADDR))

                    .build(), true /* timeout */);
@@ -579,7 +594,7 @@ public class IpClientIntegrationTest { 
    public void testDhcpClientStartWithCachedLeaseWithoutIPAddress() throws Exception {

        final DhcpPacket packet = getReplyFromDhcpLease(

                new NetworkAttributes.Builder()

                    .setMtu(new Integer(MTU))

                    .setMtu(new Integer(TEST_DEFAULT_MTU))

                    .setGroupHint(TEST_GROUPHINT)

                    .setDnsAddresses(Collections.singletonList(SERVER_ADDR))

                    .build(), false /* timeout */);
@@ -593,4 +608,23 @@ public class IpClientIntegrationTest { 
        final DhcpPacket packet = getNextDhcpPacket();

        assertTrue(DhcpDiscoverPacket.class.isInstance(packet));

    }



    @Test

    public void testRestoreInitialInterfaceMtu() throws Exception {

        final long currentTime = System.currentTimeMillis();



        // check the initial interface MTU

        assertTrue(mDependencies.getInterfaceMtu(mIfaceName) == TEST_DEFAULT_MTU);



        // change the MTU and pass the new MTU into DHCPOFFER and DHCPACK packet

        mDependencies.setMtu(TEST_MIN_MTU);

        performDhcpHandshake(true /* isSuccessLease */, TEST_LEASE_DURATION_S,

                true /* isDhcpLeaseCacheEnabled */, false /* isDhcpRapidCommitEnabled */);

        assertIpMemoryStoreNetworkAttributes(TEST_LEASE_DURATION_S, currentTime, TEST_MIN_MTU);



        mIpc.shutdown();

        HandlerUtilsKt.waitForIdle(mIpc.getHandler(), TEST_TIMEOUT_MS);

        // verify that mtu indeed has been restored

        verify(mNetd, times(1)).interfaceSetMtu(mIfaceName, TEST_DEFAULT_MTU);

    }

}

tests/unit/src/android/net/ip/IpClientTest.java

+2 −0
Original line number Diff line number Diff line
@@ -83,6 +83,7 @@ public class IpClientTest { 
    private static final String INVALID = "INVALID";

    private static final String TEST_IFNAME = "test_wlan0";

    private static final int TEST_IFINDEX = 1001;

    private static final int TEST_MTU = 1500;

    // See RFC 7042#section-2.1.2 for EUI-48 documentation values.

    private static final MacAddress TEST_MAC = MacAddress.fromString("00:00:5E:00:53:01");

    private static final int TEST_TIMEOUT_MS = 400;
@@ -122,6 +123,7 @@ public class IpClientTest { 
        when(mDependencies.getInterfaceParams(any())).thenReturn(mInterfaceParams);

        when(mDependencies.getIpMemoryStore(mContext, mNetworkStackServiceManager))

                .thenReturn(mIpMemoryStore);

        when(mDependencies.getInterfaceMtu(TEST_IFNAME)).thenReturn(TEST_MTU);



        mIfParams = null;

    }