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Inform the DNS resolver when it needs to do DNS64 synthesis.

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This is only necessary when learning the NAT64 prefix from the
RA, because if the NAT64 prefix is learned from DNS, the DNS
resolver already knows the prefix and automatically enables
DNS64 synthesis.

The DNS resolver needs to be informed of the prefix any time
clat is running on a prefix learned from an RA. This is simple to
implement: just set the prefix when starting clat if prefix
discovery is not running, and clear the prefix when stopping clat
if prefix discovery was not running. This ensures that the prefix
is cleared iff it was set.

Bug: 156914456
Test: new unit test coverage
Original-Change: https://android-review.googlesource.com/1315578
Merged-In: If8ad2d30712a6df3e207c8d3e8a129705242191e
Change-Id: If8ad2d30712a6df3e207c8d3e8a129705242191e
This commit is contained in:
Lorenzo Colitti
2020-05-26 10:13:17 +00:00
parent 0424f88915
commit 37aa693fb5
2 changed files with 60 additions and 0 deletions
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17
services/core/java/com/android/server/connectivity/Nat464Xlat.java
View File

@@ -198,6 +198,9 @@ public class Nat464Xlat extends BaseNetworkObserver {
if (mPrefixDiscoveryRunning && !isPrefixDiscoveryNeeded()) {
stopPrefixDiscovery();
}
if (!mPrefixDiscoveryRunning) {
setPrefix64(mNat64PrefixInUse);
}
}
/**
@@ -221,6 +224,10 @@ public class Nat464Xlat extends BaseNetworkObserver {
mIface = null;
mBaseIface = null;
if (!mPrefixDiscoveryRunning) {
setPrefix64(null);
}
if (isPrefixDiscoveryNeeded()) {
if (!mPrefixDiscoveryRunning) {
startPrefixDiscovery();
@@ -308,6 +315,16 @@ public class Nat464Xlat extends BaseNetworkObserver {
return requiresClat(mNetwork) && mNat64PrefixFromRa == null;
}
private void setPrefix64(IpPrefix prefix) {
final String prefixString = (prefix != null) ? prefix.toString() : "";
try {
mDnsResolver.setPrefix64(getNetId(), prefixString);
} catch (RemoteException | ServiceSpecificException e) {
Slog.e(TAG, "Error setting NAT64 prefix on netId " + getNetId() + " to "
+ prefix + ": " + e);
}
}
private void maybeHandleNat64PrefixChange() {
final IpPrefix newPrefix = selectNat64Prefix();
if (!Objects.equals(mNat64PrefixInUse, newPrefix)) {

43
tests/net/java/com/android/server/ConnectivityServiceTest.java
View File

@@ -6314,6 +6314,7 @@ public class ConnectivityServiceTest {
int netId = network.getNetId();
callback.expectAvailableCallbacksUnvalidated(mCellNetworkAgent);
inOrder.verify(mMockNetd).clatdStart(iface, pref64FromRa.toString());
inOrder.verify(mMockDnsResolver).setPrefix64(netId, pref64FromRa.toString());
inOrder.verify(mMockDnsResolver, never()).startPrefix64Discovery(netId);
callback.assertNoCallback();
assertEquals(pref64FromRa, mCm.getLinkProperties(network).getNat64Prefix());
@@ -6323,6 +6324,7 @@ public class ConnectivityServiceTest {
mCellNetworkAgent.sendLinkProperties(lp);
expectNat64PrefixChange(callback, mCellNetworkAgent, null);
inOrder.verify(mMockNetd).clatdStop(iface);
inOrder.verify(mMockDnsResolver).setPrefix64(netId, "");
inOrder.verify(mMockDnsResolver).startPrefix64Discovery(netId);
// If the RA prefix appears while DNS discovery is in progress, discovery is stopped and
@@ -6332,6 +6334,7 @@ public class ConnectivityServiceTest {
expectNat64PrefixChange(callback, mCellNetworkAgent, pref64FromRa);
inOrder.verify(mMockNetd).clatdStart(iface, pref64FromRa.toString());
inOrder.verify(mMockDnsResolver).stopPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver).setPrefix64(netId, pref64FromRa.toString());
// Withdraw the RA prefix so we can test the case where an RA prefix appears after DNS
// discovery has succeeded.
@@ -6339,6 +6342,7 @@ public class ConnectivityServiceTest {
mCellNetworkAgent.sendLinkProperties(lp);
expectNat64PrefixChange(callback, mCellNetworkAgent, null);
inOrder.verify(mMockNetd).clatdStop(iface);
inOrder.verify(mMockDnsResolver).setPrefix64(netId, "");
inOrder.verify(mMockDnsResolver).startPrefix64Discovery(netId);
mService.mNetdEventCallback.onNat64PrefixEvent(netId, true /* added */,
@@ -6355,6 +6359,7 @@ public class ConnectivityServiceTest {
inOrder.verify(mMockNetd, never()).clatdStart(eq(iface), anyString());
inOrder.verify(mMockDnsResolver, never()).stopPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).startPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).setPrefix64(eq(netId), anyString());
// If the RA is later withdrawn, nothing happens again.
lp.setNat64Prefix(null);
@@ -6364,6 +6369,7 @@ public class ConnectivityServiceTest {
inOrder.verify(mMockNetd, never()).clatdStart(eq(iface), anyString());
inOrder.verify(mMockDnsResolver, never()).stopPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).startPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).setPrefix64(eq(netId), anyString());
// If the RA prefix changes, clatd is restarted and prefix discovery is stopped.
lp.setNat64Prefix(pref64FromRa);
@@ -6377,6 +6383,7 @@ public class ConnectivityServiceTest {
pref64FromDnsStr, 96);
inOrder.verify(mMockNetd).clatdStart(iface, pref64FromRa.toString());
inOrder.verify(mMockDnsResolver).setPrefix64(netId, pref64FromRa.toString());
inOrder.verify(mMockDnsResolver, never()).startPrefix64Discovery(netId);
// If the RA prefix changes, clatd is restarted and prefix discovery is not started.
@@ -6384,7 +6391,9 @@ public class ConnectivityServiceTest {
mCellNetworkAgent.sendLinkProperties(lp);
expectNat64PrefixChange(callback, mCellNetworkAgent, newPref64FromRa);
inOrder.verify(mMockNetd).clatdStop(iface);
inOrder.verify(mMockDnsResolver).setPrefix64(netId, "");
inOrder.verify(mMockNetd).clatdStart(iface, newPref64FromRa.toString());
inOrder.verify(mMockDnsResolver).setPrefix64(netId, newPref64FromRa.toString());
inOrder.verify(mMockDnsResolver, never()).stopPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).startPrefix64Discovery(netId);
@@ -6397,11 +6406,45 @@ public class ConnectivityServiceTest {
inOrder.verify(mMockNetd, never()).clatdStart(eq(iface), anyString());
inOrder.verify(mMockDnsResolver, never()).stopPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).startPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).setPrefix64(eq(netId), anyString());
// The transition between no prefix and DNS prefix is tested in testStackedLinkProperties.
// If the same prefix is learned first by DNS and then by RA, and clat is later stopped,
// (e.g., because the network disconnects) setPrefix64(netid, "") is never called.
lp.setNat64Prefix(null);
mCellNetworkAgent.sendLinkProperties(lp);
expectNat64PrefixChange(callback, mCellNetworkAgent, null);
inOrder.verify(mMockNetd).clatdStop(iface);
inOrder.verify(mMockDnsResolver).setPrefix64(netId, "");
inOrder.verify(mMockDnsResolver).startPrefix64Discovery(netId);
mService.mNetdEventCallback.onNat64PrefixEvent(netId, true /* added */,
pref64FromDnsStr, 96);
expectNat64PrefixChange(callback, mCellNetworkAgent, pref64FromDns);
inOrder.verify(mMockNetd).clatdStart(iface, pref64FromDns.toString());
inOrder.verify(mMockDnsResolver, never()).setPrefix64(eq(netId), any());
lp.setNat64Prefix(pref64FromDns);
mCellNetworkAgent.sendLinkProperties(lp);
callback.assertNoCallback();
inOrder.verify(mMockNetd, never()).clatdStop(iface);
inOrder.verify(mMockNetd, never()).clatdStart(eq(iface), anyString());
inOrder.verify(mMockDnsResolver, never()).stopPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).startPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).setPrefix64(eq(netId), anyString());
// When tearing down a network, clat state is only updated after CALLBACK_LOST is fired, but
// before CONNECTIVITY_ACTION is sent. Wait for CONNECTIVITY_ACTION before verifying that
// clat has been stopped, or the test will be flaky.
ConditionVariable cv = registerConnectivityBroadcast(1);
mCellNetworkAgent.disconnect();
callback.expectCallback(CallbackEntry.LOST, mCellNetworkAgent);
waitFor(cv);
inOrder.verify(mMockNetd).clatdStop(iface);
inOrder.verify(mMockDnsResolver).stopPrefix64Discovery(netId);
inOrder.verify(mMockDnsResolver, never()).setPrefix64(eq(netId), anyString());
mCm.unregisterNetworkCallback(callback);
}