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Merge "Random select started prefix range" into main

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This commit is contained in:
Mark Chien 2023-12-05 05:25:18 +00:00 • committed by Gerrit Code Review
commit 78c0d088d7
3 changed files with 77 additions and 1 deletions
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27
Tethering/src/com/android/networkstack/tethering/PrivateAddressCoordinator.java
View file

@ -189,7 +189,10 @@ public class PrivateAddressCoordinator {
return cachedAddress;
}
for (IpPrefix prefixRange : mTetheringPrefixes) {
final int prefixIndex = getStartedPrefixIndex();
for (int i = 0; i < mTetheringPrefixes.size(); i++) {
final IpPrefix prefixRange = mTetheringPrefixes.get(
(prefixIndex + i) % mTetheringPrefixes.size());
final LinkAddress newAddress = chooseDownstreamAddress(prefixRange);
if (newAddress != null) {
mDownstreams.add(ipServer);
@ -202,6 +205,28 @@ public class PrivateAddressCoordinator {
return null;
}
private int getStartedPrefixIndex() {
if (!mConfig.isRandomPrefixBaseEnabled()) return 0;
final int random = getRandomInt() & 0xffffff;
// This is to select the starting prefix range (/8, /12, or /16) instead of the actual
// LinkAddress. To avoid complex operations in the selection logic and make the selected
// rate approximate consistency with that /8 is around 2^4 times of /12 and /12 is around
// 2^4 times of /16, we simply define a map between the value and the prefix value like
// this:
//
// Value 0 ~ 0xffff (65536/16777216 = 0.39%) -> 192.168.0.0/16
// Value 0x10000 ~ 0xfffff (983040/16777216 = 5.86%) -> 172.16.0.0/12
// Value 0x100000 ~ 0xffffff (15728640/16777216 = 93.7%) -> 10.0.0.0/8
if (random > 0xfffff) {
return 2;
} else if (random > 0xffff) {
return 1;
} else {
return 0;
}
}
private int getPrefixBaseAddress(final IpPrefix prefix) {
return inet4AddressToIntHTH((Inet4Address) prefix.getAddress());
}

12
Tethering/src/com/android/networkstack/tethering/TetheringConfiguration.java
View file

@ -130,6 +130,8 @@ public class TetheringConfiguration {
public static final String TETHER_ENABLE_WEAR_TETHERING =
"tether_enable_wear_tethering";
public static final String TETHER_FORCE_RANDOM_PREFIX_BASE_SELECTION =
"tether_force_random_prefix_base_selection";
/**
* Default value that used to periodic polls tether offload stats from tethering offload HAL
* to make the data warnings work.
@ -171,6 +173,7 @@ public class TetheringConfiguration {
private final int mP2pLeasesSubnetPrefixLength;
private final boolean mEnableWearTethering;
private final boolean mRandomPrefixBase;
private final int mUsbTetheringFunction;
protected final ContentResolver mContentResolver;
@ -288,6 +291,8 @@ public class TetheringConfiguration {
mEnableWearTethering = shouldEnableWearTethering(ctx);
mRandomPrefixBase = mDeps.isFeatureEnabled(ctx, TETHER_FORCE_RANDOM_PREFIX_BASE_SELECTION);
configLog.log(toString());
}
@ -376,6 +381,10 @@ public class TetheringConfiguration {
return mEnableWearTethering;
}
public boolean isRandomPrefixBaseEnabled() {
return mRandomPrefixBase;
}
/** Does the dumping.*/
public void dump(PrintWriter pw) {
pw.print("activeDataSubId: ");
@ -426,6 +435,9 @@ public class TetheringConfiguration {
pw.print("mUsbTetheringFunction: ");
pw.println(isUsingNcm() ? "NCM" : "RNDIS");
pw.print("mRandomPrefixBase: ");
pw.println(mRandomPrefixBase);
}
/** Returns the string representation of this object.*/

39
Tethering/tests/unit/src/com/android/networkstack/tethering/PrivateAddressCoordinatorTest.java
View file

@ -30,6 +30,7 @@ import static com.android.networkstack.tethering.util.PrefixUtils.asIpPrefix;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotEquals;
import static org.junit.Assert.assertTrue;
import static org.mockito.Mockito.never;
import static org.mockito.Mockito.reset;
import static org.mockito.Mockito.spy;
@ -104,6 +105,7 @@ public final class PrivateAddressCoordinatorTest {
when(mContext.getSystemService(Context.CONNECTIVITY_SERVICE)).thenReturn(mConnectivityMgr);
when(mConnectivityMgr.getAllNetworks()).thenReturn(mAllNetworks);
when(mConfig.shouldEnableWifiP2pDedicatedIp()).thenReturn(false);
when(mConfig.isRandomPrefixBaseEnabled()).thenReturn(false);
setUpIpServers();
mPrivateAddressCoordinator = spy(new PrivateAddressCoordinator(mContext, mConfig));
}
@ -572,4 +574,41 @@ public final class PrivateAddressCoordinatorTest {
assertEquals("Wrong local hotspot prefix: ", new LinkAddress("192.168.134.5/24"),
localHotspotAddress);
}
@Test
public void testStartedPrefixRange() throws Exception {
when(mConfig.isRandomPrefixBaseEnabled()).thenReturn(true);
startedPrefixBaseTest("192.168.0.0/16", 0);
startedPrefixBaseTest("192.168.0.0/16", 1);
startedPrefixBaseTest("192.168.0.0/16", 0xffff);
startedPrefixBaseTest("172.16.0.0/12", 0x10000);
startedPrefixBaseTest("172.16.0.0/12", 0x11111);
startedPrefixBaseTest("172.16.0.0/12", 0xfffff);
startedPrefixBaseTest("10.0.0.0/8", 0x100000);
startedPrefixBaseTest("10.0.0.0/8", 0x1fffff);
startedPrefixBaseTest("10.0.0.0/8", 0xffffff);
startedPrefixBaseTest("192.168.0.0/16", 0x1000000);
}
private void startedPrefixBaseTest(final String expected, final int randomIntForPrefixBase)
throws Exception {
mPrivateAddressCoordinator = spy(new PrivateAddressCoordinator(mContext, mConfig));
when(mPrivateAddressCoordinator.getRandomInt()).thenReturn(randomIntForPrefixBase);
final LinkAddress address = requestDownstreamAddress(mHotspotIpServer,
CONNECTIVITY_SCOPE_GLOBAL, false /* useLastAddress */);
final IpPrefix prefixBase = new IpPrefix(expected);
assertTrue(address + " is not part of " + prefixBase,
prefixBase.containsPrefix(asIpPrefix(address)));
}
}