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Commit 7ae2ec39 authored by Xiao Ma's avatar Xiao Ma
Browse files

Rollback to DHCPDISCOVER w/o Rapid Commit if handshake doesn't succeeds. 

To prevent the potential interoperability issue with Rapid Commit
option, limit the first 3 DHCPDISCOVER packets taking this option.
If DhcpClient doesn't receive any valid DHCPACK within the first
3 packet (re)transmission, then just rollback to DHCPDISCOVER
without Rapid Commit option in the subsequent transmission.

Bug: 198226242
Test: atest NetworkStackIntegrationTests
Change-Id: Id926c94aa96a5a36d91f82371e472eac7361114e
parent 0d79a43a

src/android/net/dhcp/DhcpClient.java

+6 −1
Original line number Diff line number Diff line
@@ -747,9 +747,14 @@ public class DhcpClient extends StateMachine { 
    }



    private boolean sendDiscoverPacket() {

        // When Rapid Commit option is enabled, limit only the first 3 DHCPDISCOVER packets

        // taking Rapid Commit option, in order to prevent the potential interoperability issue

        // and be able to rollback later. See {@link DHCP_TIMEOUT_MS} for the (re)transmission

        // schedule with 10% jitter.

        final boolean requestRapidCommit = isDhcpRapidCommitEnabled() && (getSecs() <= 4);

        final ByteBuffer packet = DhcpPacket.buildDiscoverPacket(

                DhcpPacket.ENCAP_L2, mTransactionId, getSecs(), mHwAddr,

                DO_UNICAST, getRequestedParams(), isDhcpRapidCommitEnabled(), mHostname,

                DO_UNICAST, getRequestedParams(), requestRapidCommit, mHostname,

                mConfiguration.options);

        mMetrics.incrementCountForDiscover();

        return transmitPacket(packet, "DHCPDISCOVER", DhcpPacket.ENCAP_L2, INADDR_BROADCAST);

src/android/net/dhcp/DhcpPacket.java

+2 −1
Original line number Diff line number Diff line
@@ -321,7 +321,8 @@ public abstract class DhcpPacket { 
     * packet may include this option.

     */

    public static final byte DHCP_RAPID_COMMIT = 80;

    protected boolean mRapidCommit;

    @VisibleForTesting(otherwise = VisibleForTesting.PROTECTED)

    public boolean mRapidCommit;



    /**

     * DHCP IPv6-Only Preferred Option(RFC 8925).

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

+35 −0
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ import static org.junit.Assert.assertTrue; 
import static org.junit.Assume.assumeFalse;

import static org.junit.Assume.assumeTrue;

import static org.mockito.ArgumentMatchers.anyInt;

import static org.mockito.ArgumentMatchers.anyLong;

import static org.mockito.ArgumentMatchers.contains;

import static org.mockito.ArgumentMatchers.longThat;

import static org.mockito.Mockito.any;
@@ -592,6 +593,8 @@ public abstract class IpClientIntegrationTestCommon { 
        if (useNetworkStackSignature()) {

            setUpMocks();

            setUpIpClient();

            // Enable packet retransmit alarm in DhcpClient.

            enableRealAlarm("DhcpClient." + mIfaceName + ".KICK");

        }



        mIIpClient = makeIIpClient(mIfaceName, mCb);
@@ -688,6 +691,17 @@ public abstract class IpClientIntegrationTestCommon { 
        }

    }



    private void enableRealAlarm(String cmdName) {

        doAnswer((inv) -> {

            final Context context = InstrumentationRegistry.getTargetContext();

            final AlarmManager alarmManager = context.getSystemService(AlarmManager.class);

            alarmManager.setExact(inv.getArgument(0), inv.getArgument(1), inv.getArgument(2),

                    inv.getArgument(3), inv.getArgument(4));

            return null;

        }).when(mAlarm).setExact(anyInt(), anyLong(), eq(cmdName), any(OnAlarmListener.class),

                any(Handler.class));

    }



    private IpClient makeIpClient() throws Exception {

        IpClient ipc = new IpClient(mContext, mIfaceName, mCb, mNetworkObserverRegistry,

                mNetworkStackServiceManager, mDependencies);
@@ -1388,6 +1402,27 @@ public abstract class IpClientIntegrationTestCommon { 
        assertIpMemoryStoreNetworkAttributes(TEST_LEASE_DURATION_S, currentTime, TEST_DEFAULT_MTU);

    }



    @Test

    public void testRollbackFromRapidCommitOption() throws Exception {

        startIpClientProvisioning(false /* isDhcpLeaseCacheEnabled */,

                true /* isDhcpRapidCommitEnabled */, false /* isPreConnectionEnabled */,

                false /* isDhcpIpConflictDetectEnabled */, false /* isIPv6OnlyPreferredEnabled */);



        final List<DhcpPacket> discoverList = new ArrayList<DhcpPacket>();

        DhcpPacket packet;

        do {

            packet = getNextDhcpPacket();

            assertTrue(packet instanceof DhcpDiscoverPacket);

            discoverList.add(packet);

        } while (discoverList.size() < 4);



        // Check the only first 3 DHCPDISCOVERs take rapid commit option.

        assertTrue(discoverList.get(0).mRapidCommit);

        assertTrue(discoverList.get(1).mRapidCommit);

        assertTrue(discoverList.get(2).mRapidCommit);

        assertFalse(discoverList.get(3).mRapidCommit);

    }



    @Test @SignatureRequiredTest(reason = "TODO: evaluate whether signature perms are required")

    public void testDhcpClientStartWithCachedInfiniteLease() throws Exception {

        final DhcpPacket packet = getReplyFromDhcpLease(