Merge "Gracefully handle integer overflows." into oc-mr1-dev (19f40da9) · Commits · e / os / android_frameworks_base

services/core/java/com/android/server/net/NetworkStatsCollection.java

+32 −4

Original line number	Diff line number	Diff line
		@@ -177,6 +177,34 @@ public class NetworkStatsCollection implements FileRotator.Reader {
		}
		}

		/**
		* Safely multiple a value by a rational.
		* <p>
		* Internally it uses integer-based math whenever possible, but switches
		* over to double-based math if values would overflow.
		*/
		@VisibleForTesting
		public static long multiplySafe(long value, long num, long den) {
		long x = value;
		long y = num;

		// Logic shamelessly borrowed from Math.multiplyExact()
		long r = x * y;
		long ax = Math.abs(x);
		long ay = Math.abs(y);
		if (((ax \| ay) >>> 31 != 0)) {
		// Some bits greater than 2^31 that might cause overflow
		// Check the result using the divide operator
		// and check for the special case of Long.MIN_VALUE * -1
		if (((y != 0) && (r / y != x)) \|\|
		(x == Long.MIN_VALUE && y == -1)) {
		// Use double math to avoid overflowing
		return (long) (((double) num / den) * value);
		}
		}
		return r / den;
		}

		public int[] getRelevantUids(@NetworkStatsAccess.Level int accessLevel) {
		return getRelevantUids(accessLevel, Binder.getCallingUid());
		}
		@@ -274,8 +302,8 @@ public class NetworkStatsCollection implements FileRotator.Reader {
		final long rawRxBytes = entry.rxBytes;
		final long rawTxBytes = entry.txBytes;
		final long targetBytes = augmentPlan.getDataUsageBytes();
		final long targetRxBytes = (rawRxBytes * targetBytes) / rawBytes;
		final long targetTxBytes = (rawTxBytes * targetBytes) / rawBytes;
		final long targetRxBytes = multiplySafe(targetBytes, rawRxBytes, rawBytes);
		final long targetTxBytes = multiplySafe(targetBytes, rawTxBytes, rawBytes);

		// Scale all matching buckets to reach anchor target
		final long beforeTotal = combined.getTotalBytes();
		@@ -283,8 +311,8 @@ public class NetworkStatsCollection implements FileRotator.Reader {
		combined.getValues(i, entry);
		if (entry.bucketStart >= augmentStart
		&& entry.bucketStart + entry.bucketDuration <= augmentEnd) {
		entry.rxBytes = (entry.rxBytes * targetRxBytes) / rawRxBytes;
		entry.txBytes = (entry.txBytes * targetTxBytes) / rawTxBytes;
		entry.rxBytes = multiplySafe(targetRxBytes, entry.rxBytes, rawRxBytes);
		entry.txBytes = multiplySafe(targetTxBytes, entry.txBytes, rawTxBytes);
		// We purposefully clear out packet counters to indicate
		// that this data has been augmented.
		entry.rxPackets = 0;

tests/net/java/com/android/server/net/NetworkStatsCollectionTest.java

+64 −0

Original line number	Diff line number	Diff line
		@@ -27,7 +27,10 @@ import static android.os.Process.myUid;
		import static android.text.format.DateUtils.HOUR_IN_MILLIS;
		import static android.text.format.DateUtils.MINUTE_IN_MILLIS;

		import static com.android.server.net.NetworkStatsCollection.multiplySafe;

		import android.content.res.Resources;
		import android.net.ConnectivityManager;
		import android.net.NetworkIdentity;
		import android.net.NetworkStats;
		import android.net.NetworkStatsHistory;
		@@ -40,6 +43,7 @@ import android.test.AndroidTestCase;
		import android.test.MoreAsserts;
		import android.test.suitebuilder.annotation.SmallTest;
		import android.text.format.DateUtils;
		import android.util.RecurrenceRule;

		import com.android.frameworks.tests.net.R;

		@@ -53,6 +57,9 @@ import java.io.File;
		import java.io.FileOutputStream;
		import java.io.InputStream;
		import java.io.OutputStream;
		import java.time.Clock;
		import java.time.Instant;
		import java.time.ZoneId;
		import java.time.ZonedDateTime;
		import java.util.ArrayList;
		import java.util.List;
		@@ -70,14 +77,27 @@ public class NetworkStatsCollectionTest extends AndroidTestCase {
		private static final long TIME_B = 1326110400000L; // UTC: Monday 9th January 2012 12:00:00 PM
		private static final long TIME_C = 1326132000000L; // UTC: Monday 9th January 2012 06:00:00 PM

		private static Clock sOriginalClock;

		@Override
		public void setUp() throws Exception {
		super.setUp();
		sOriginalClock = RecurrenceRule.sClock;

		// ignore any device overlay while testing
		NetworkTemplate.forceAllNetworkTypes();
		}

		@Override
		protected void tearDown() throws Exception {
		super.tearDown();
		RecurrenceRule.sClock = sOriginalClock;
		}

		private void setClock(Instant instant) {
		RecurrenceRule.sClock = Clock.fixed(instant, ZoneId.systemDefault());
		}

		public void testReadLegacyNetwork() throws Exception {
		final File testFile = new File(getContext().getFilesDir(), TEST_FILE);
		stageFile(R.raw.netstats_v1, testFile);
		@@ -238,6 +258,9 @@ public class NetworkStatsCollectionTest extends AndroidTestCase {
		final NetworkStatsCollection collection = new NetworkStatsCollection(30 * MINUTE_IN_MILLIS);
		collection.readLegacyNetwork(testFile);

		// We're in the future, but not that far off
		setClock(Instant.parse("2012-06-01T00:00:00.00Z"));

		// Test a bunch of plans that should result in no augmentation
		final List<SubscriptionPlan> plans = new ArrayList<>();

		@@ -416,6 +439,28 @@ public class NetworkStatsCollectionTest extends AndroidTestCase {
		}
		}

		public void testAugmentPlanGigantic() throws Exception {
		// We're in the future, but not that far off
		setClock(Instant.parse("2012-06-01T00:00:00.00Z"));

		// Create a simple history with a ton of measured usage
		final NetworkStatsCollection large = new NetworkStatsCollection(HOUR_IN_MILLIS);
		final NetworkIdentitySet ident = new NetworkIdentitySet();
		ident.add(new NetworkIdentity(ConnectivityManager.TYPE_MOBILE, -1, TEST_IMSI, null,
		false, true));
		large.recordData(ident, UID_ALL, SET_ALL, TAG_NONE, TIME_A, TIME_B,
		new NetworkStats.Entry(12_730_893_164L, 1, 0, 0, 0));

		// Verify untouched total
		assertEquals(12_730_893_164L, getHistory(large, null, TIME_A, TIME_C).getTotalBytes());

		// Verify anchor that might cause overflows
		final SubscriptionPlan plan = SubscriptionPlan.Builder
		.createRecurringMonthly(ZonedDateTime.parse("2012-01-09T00:00:00.00Z"))
		.setDataUsage(4_939_212_390L, TIME_B).build();
		assertEquals(4_939_212_386L, getHistory(large, plan, TIME_A, TIME_C).getTotalBytes());
		}

		public void testRounding() throws Exception {
		final NetworkStatsCollection coll = new NetworkStatsCollection(HOUR_IN_MILLIS);

		@@ -437,6 +482,25 @@ public class NetworkStatsCollectionTest extends AndroidTestCase {
		assertEquals(TIME_A - HOUR_IN_MILLIS, coll.roundDown(TIME_A - 1));
		}

		public void testMultiplySafe() {
		assertEquals(25, multiplySafe(50, 1, 2));
		assertEquals(100, multiplySafe(50, 2, 1));

		assertEquals(-10, multiplySafe(30, -1, 3));
		assertEquals(0, multiplySafe(30, 0, 3));
		assertEquals(10, multiplySafe(30, 1, 3));
		assertEquals(20, multiplySafe(30, 2, 3));
		assertEquals(30, multiplySafe(30, 3, 3));
		assertEquals(40, multiplySafe(30, 4, 3));

		assertEquals(100_000_000_000L,
		multiplySafe(300_000_000_000L, 10_000_000_000L, 30_000_000_000L));
		assertEquals(100_000_000_010L,
		multiplySafe(300_000_000_000L, 10_000_000_001L, 30_000_000_000L));
		assertEquals(823_202_048L,
		multiplySafe(4_939_212_288L, 2_121_815_528L, 12_730_893_165L));
		}

		/**
		* Copy a {@link Resources#openRawResource(int)} into {@link File} for
		* testing purposes.