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Merge "Gracefully handle integer overflows." into oc-mr1-dev

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am: 4d2a8d7203

Change-Id: I6ed70a40ad3e6df55e7669fedfe5b34faf95bd9f
This commit is contained in:
Jeff Sharkey
2017-09-02 02:07:25 +00:00
committed by android-build-merger
parent 98790fa7f0 4d2a8d7203
commit 19f40da9fa
2 changed files with 96 additions and 4 deletions
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36
services/core/java/com/android/server/net/NetworkStatsCollection.java
View File

@@ -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;

64
tests/net/java/com/android/server/net/NetworkStatsCollectionTest.java
View File

@@ -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.