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Commit 2195751c authored by Lorenzo Colitti's avatar Lorenzo Colitti
Browse files

Address comments on ag/11204387. 

Add comments and slightly increase test coverage.

Bug: 153694684
Test: new test coverage in IpClientIntegrationTest
Change-Id: I160a0801449cbe9e66976eaacdd3a914adc3d341
parent eb138e5d

src/android/net/ip/IpClientLinkObserver.java

+10 −2
Original line number Diff line number Diff line
@@ -282,6 +282,12 @@ public class IpClientLinkObserver implements NetworkObserver { 
        }



        private final AlarmManager.OnAlarmListener mExpirePref64Alarm = () -> {

            // TODO: in the rare case where the alarm fires and posts the lambda to the handler

            // thread while we are processing an RA that changes the lifetime of the same prefix,

            // this code will run anyway even if the alarm is rescheduled or cancelled. If the

            // lifetime in the RA is zero this doesn't matter (we just harmlessly cancel the alarm

            // one extra time) but if the lifetime is nonzero then the prefix will be added and

            // immediately removed by this code.

            updatePref64(mShim.getNat64Prefix(mLinkProperties),

                    mNat64PrefixExpiry, mNat64PrefixExpiry);

        };
@@ -321,9 +327,11 @@ public class IpClientLinkObserver implements NetworkObserver { 


            // If we already have a prefix, continue using it and ignore the new one. Stopping and

            // restarting clatd is disruptive because it will break existing IPv4 connections.

            // TODO: this means that if we receive an RA that adds a new prefix and deletes the old

            // Note: this means that if we receive an RA that adds a new prefix and deletes the old

            // prefix, we might receive and ignore the new prefix, then delete the old prefix, and

            // have no prefix until the next RA is received.

            // have no prefix until the next RA is received. This is because the kernel returns ND

            // user options one at a time even if they are in the same RA.

            // TODO: keep track of the last few prefixes seen, like DnsServerRepository does.

            if (mNat64PrefixExpiry > now) return;



            // The current prefix has expired. Either replace it with the new one or delete it.

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

+9 −1
Original line number Diff line number Diff line
@@ -1481,6 +1481,14 @@ public class IpClientIntegrationTest { 
        expectNoNat64PrefixUpdate(inOrder, prefix);

        reset(mCb, mAlarm);



        // Reduce the lifetime and expect to reschedule expiry.

        pref64 = new StructNdOptPref64(prefix, 1500).toByteBuffer();

        ra = buildRaPacket(pio, rdnss, pref64);

        mPacketReader.sendResponse(ra);

        pref64Alarm = expectAlarmSet(inOrder, "PREF64", 1496);

        expectNoNat64PrefixUpdate(inOrder, prefix);

        reset(mCb, mAlarm);



        // Withdraw the prefix and expect it to be set to null.

        pref64 = new StructNdOptPref64(prefix, 0).toByteBuffer();

        ra = buildRaPacket(pio, rdnss, pref64);
@@ -1506,7 +1514,7 @@ public class IpClientIntegrationTest { 
        expectNoNat64PrefixUpdate(inOrder, prefix);

        reset(mCb, mAlarm);



        // Withdraw the prefix and expect to switch to the new prefix.

        // Withdraw the old prefix and continue to announce the new one. Expect a prefix change.

        pref64 = new StructNdOptPref64(prefix, 0).toByteBuffer();

        ra = buildRaPacket(pio, rdnss, pref64, otherPref64);

        mPacketReader.sendResponse(ra);