services/core/java/com/android/server/net/NetworkStatsFactory.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2011 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.android.server.net;

 import static android.net.NetworkStats.INTERFACES_ALL;
 import static android.net.NetworkStats.SET_ALL;
 import static android.net.NetworkStats.TAG_ALL;
 import static android.net.NetworkStats.TAG_NONE;
 import static android.net.NetworkStats.UID_ALL;

 import static com.android.server.NetworkManagementSocketTagger.kernelToTag;

 import android.annotation.Nullable;
 import android.net.INetd;
 import android.net.NetworkStats;
 import android.net.util.NetdService;
 import android.os.RemoteException;
 import android.os.StrictMode;
 import android.os.SystemClock;

 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.net.VpnInfo;
 import com.android.internal.util.ArrayUtils;
 import com.android.internal.util.ProcFileReader;

 import libcore.io.IoUtils;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.net.ProtocolException;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;

 /**
  * Creates {@link NetworkStats} instances by parsing various {@code /proc/}
  * files as needed.
  *
  * @hide
  */
 public class NetworkStatsFactory {
     private static final String TAG = "NetworkStatsFactory";

     private static final boolean USE_NATIVE_PARSING = true;
     private static final boolean SANITY_CHECK_NATIVE = false;

     /** Path to {@code /proc/net/xt_qtaguid/iface_stat_all}. */
     private final File mStatsXtIfaceAll;
     /** Path to {@code /proc/net/xt_qtaguid/iface_stat_fmt}. */
     private final File mStatsXtIfaceFmt;
     /** Path to {@code /proc/net/xt_qtaguid/stats}. */
     private final File mStatsXtUid;

     private final boolean mUseBpfStats;

     private INetd mNetdService;

     /**
      * Guards persistent data access in this class
      *
      * <p>In order to prevent deadlocks, critical sections protected by this lock SHALL NOT call out
      * to other code that will acquire other locks within the system server. See b/134244752.
      */
     private final Object mPersistentDataLock = new Object();

     /** Set containing info about active VPNs and their underlying networks. */
     private volatile VpnInfo[] mVpnInfos = new VpnInfo[0];

     // A persistent snapshot of cumulative stats since device start
     @GuardedBy("mPersistentDataLock")
     private NetworkStats mPersistSnapshot;

     // The persistent snapshot of tun and 464xlat adjusted stats since device start
     @GuardedBy("mPersistentDataLock")
     private NetworkStats mTunAnd464xlatAdjustedStats;

     /**
      * (Stacked interface) -> (base interface) association for all connected ifaces since boot.
      *
      * Because counters must never roll backwards, once a given interface is stacked on top of an
      * underlying interface, the stacked interface can never be stacked on top of
      * another interface. */
     private final ConcurrentHashMap<String, String> mStackedIfaces
             = new ConcurrentHashMap<>();

     /** Informs the factory of a new stacked interface. */
     public void noteStackedIface(String stackedIface, String baseIface) {
         if (stackedIface != null && baseIface != null) {
             mStackedIfaces.put(stackedIface, baseIface);
         }
     }

     /**
      * Set active VPN information for data usage migration purposes
      *
      * <p>Traffic on TUN-based VPNs inherently all appear to be originated from the VPN providing
      * app's UID. This method is used to support migration of VPN data usage, ensuring data is
      * accurately billed to the real owner of the traffic.
      *
      * @param vpnArray The snapshot of the currently-running VPNs.
      */
     public void updateVpnInfos(VpnInfo[] vpnArray) {
         mVpnInfos = vpnArray.clone();
     }

     /**
      * Get a set of interfaces containing specified ifaces and stacked interfaces.
      *
      * <p>The added stacked interfaces are ifaces stacked on top of the specified ones, or ifaces
      * on which the specified ones are stacked. Stacked interfaces are those noted with
      * {@link #noteStackedIface(String, String)}, but only interfaces noted before this method
      * is called are guaranteed to be included.
      */
     public String[] augmentWithStackedInterfaces(@Nullable String[] requiredIfaces) {
         if (requiredIfaces == NetworkStats.INTERFACES_ALL) {
             return null;
         }

         HashSet<String> relatedIfaces = new HashSet<>(Arrays.asList(requiredIfaces));
         // ConcurrentHashMap's EntrySet iterators are "guaranteed to traverse
         // elements as they existed upon construction exactly once, and may
         // (but are not guaranteed to) reflect any modifications subsequent to construction".
         // This is enough here.
         for (Map.Entry<String, String> entry : mStackedIfaces.entrySet()) {
             if (relatedIfaces.contains(entry.getKey())) {
                 relatedIfaces.add(entry.getValue());
             } else if (relatedIfaces.contains(entry.getValue())) {
                 relatedIfaces.add(entry.getKey());
             }
         }

         String[] outArray = new String[relatedIfaces.size()];
         return relatedIfaces.toArray(outArray);
     }

     /**
      * Applies 464xlat adjustments with ifaces noted with {@link #noteStackedIface(String, String)}.
      * @see NetworkStats#apply464xlatAdjustments(NetworkStats, NetworkStats, Map, boolean)
      */
     public void apply464xlatAdjustments(NetworkStats baseTraffic,
             NetworkStats stackedTraffic, boolean useBpfStats) {
         NetworkStats.apply464xlatAdjustments(baseTraffic, stackedTraffic, mStackedIfaces,
                 useBpfStats);
     }

     public NetworkStatsFactory() {
         this(new File("/proc/"), new File("/sys/fs/bpf/map_netd_app_uid_stats_map").exists());
     }

     @VisibleForTesting
     public NetworkStatsFactory(File procRoot, boolean useBpfStats) {
         mStatsXtIfaceAll = new File(procRoot, "net/xt_qtaguid/iface_stat_all");
         mStatsXtIfaceFmt = new File(procRoot, "net/xt_qtaguid/iface_stat_fmt");
         mStatsXtUid = new File(procRoot, "net/xt_qtaguid/stats");
         mUseBpfStats = useBpfStats;
         synchronized (mPersistentDataLock) {
             mPersistSnapshot = new NetworkStats(SystemClock.elapsedRealtime(), -1);
             mTunAnd464xlatAdjustedStats = new NetworkStats(SystemClock.elapsedRealtime(), -1);
         }
     }

     public NetworkStats readBpfNetworkStatsDev() throws IOException {
         final NetworkStats stats = new NetworkStats(SystemClock.elapsedRealtime(), 6);
         if (nativeReadNetworkStatsDev(stats) != 0) {
             throw new IOException("Failed to parse bpf iface stats");
         }
         return stats;
     }

     /**
      * Parse and return interface-level summary {@link NetworkStats} measured
      * using {@code /proc/net/dev} style hooks, which may include non IP layer
      * traffic. Values monotonically increase since device boot, and may include
      * details about inactive interfaces.
      *
      * @throws IllegalStateException when problem parsing stats.
      */
     public NetworkStats readNetworkStatsSummaryDev() throws IOException {

         // Return xt_bpf stats if switched to bpf module.
         if (mUseBpfStats)
             return readBpfNetworkStatsDev();

         final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskReads();

         final NetworkStats stats = new NetworkStats(SystemClock.elapsedRealtime(), 6);
         final NetworkStats.Entry entry = new NetworkStats.Entry();

         ProcFileReader reader = null;
         try {
             reader = new ProcFileReader(new FileInputStream(mStatsXtIfaceAll));

             while (reader.hasMoreData()) {
                 entry.iface = reader.nextString();
                 entry.uid = UID_ALL;
                 entry.set = SET_ALL;
                 entry.tag = TAG_NONE;

                 final boolean active = reader.nextInt() != 0;

                 // always include snapshot values
                 entry.rxBytes = reader.nextLong();
                 entry.rxPackets = reader.nextLong();
                 entry.txBytes = reader.nextLong();
                 entry.txPackets = reader.nextLong();

                 // fold in active numbers, but only when active
                 if (active) {
                     entry.rxBytes += reader.nextLong();
                     entry.rxPackets += reader.nextLong();
                     entry.txBytes += reader.nextLong();
                     entry.txPackets += reader.nextLong();
                 }

                 stats.addEntry(entry);
                 reader.finishLine();
             }
         } catch (NullPointerException|NumberFormatException e) {
             throw protocolExceptionWithCause("problem parsing stats", e);
         } finally {
             IoUtils.closeQuietly(reader);
             StrictMode.setThreadPolicy(savedPolicy);
         }
         return stats;
     }

     /**
      * Parse and return interface-level summary {@link NetworkStats}. Designed
      * to return only IP layer traffic. Values monotonically increase since
      * device boot, and may include details about inactive interfaces.
      *
      * @throws IllegalStateException when problem parsing stats.
      */
     public NetworkStats readNetworkStatsSummaryXt() throws IOException {

         // Return xt_bpf stats if qtaguid  module is replaced.
         if (mUseBpfStats)
             return readBpfNetworkStatsDev();

         final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskReads();

         // return null when kernel doesn't support
         if (!mStatsXtIfaceFmt.exists()) return null;

         final NetworkStats stats = new NetworkStats(SystemClock.elapsedRealtime(), 6);
         final NetworkStats.Entry entry = new NetworkStats.Entry();

         ProcFileReader reader = null;
         try {
             // open and consume header line
             reader = new ProcFileReader(new FileInputStream(mStatsXtIfaceFmt));
             reader.finishLine();

             while (reader.hasMoreData()) {
                 entry.iface = reader.nextString();
                 entry.uid = UID_ALL;
                 entry.set = SET_ALL;
                 entry.tag = TAG_NONE;

                 entry.rxBytes = reader.nextLong();
                 entry.rxPackets = reader.nextLong();
                 entry.txBytes = reader.nextLong();
                 entry.txPackets = reader.nextLong();

                 stats.addEntry(entry);
                 reader.finishLine();
             }
         } catch (NullPointerException|NumberFormatException e) {
             throw protocolExceptionWithCause("problem parsing stats", e);
         } finally {
             IoUtils.closeQuietly(reader);
             StrictMode.setThreadPolicy(savedPolicy);
         }
         return stats;
     }

     public NetworkStats readNetworkStatsDetail() throws IOException {
         return readNetworkStatsDetail(UID_ALL, INTERFACES_ALL, TAG_ALL);
     }

     @GuardedBy("mPersistentDataLock")
     private void requestSwapActiveStatsMapLocked() throws RemoteException {
         // Ask netd to do a active map stats swap. When the binder call successfully returns,
         // the system server should be able to safely read and clean the inactive map
         // without race problem.
         if (mNetdService == null) {
             mNetdService = NetdService.getInstance();
         }
         mNetdService.trafficSwapActiveStatsMap();
     }

     /**
      * Reads the detailed UID stats based on the provided parameters
      *
      * @param limitUid the UID to limit this query to
      * @param limitIfaces the interfaces to limit this query to. Use {@link
      *     NetworkStats.INTERFACES_ALL} to select all interfaces
      * @param limitTag the tags to limit this query to
      * @return the NetworkStats instance containing network statistics at the present time.
      */
     public NetworkStats readNetworkStatsDetail(
             int limitUid, String[] limitIfaces, int limitTag) throws IOException {
         // In order to prevent deadlocks, anything protected by this lock MUST NOT call out to other
         // code that will acquire other locks within the system server. See b/134244752.
         synchronized (mPersistentDataLock) {
             // Take a reference. If this gets swapped out, we still have the old reference.
             final VpnInfo[] vpnArray = mVpnInfos;
             // Take a defensive copy. mPersistSnapshot is mutated in some cases below
             final NetworkStats prev = mPersistSnapshot.clone();

             if (USE_NATIVE_PARSING) {
                 final NetworkStats stats =
                         new NetworkStats(SystemClock.elapsedRealtime(), 0 /* initialSize */);
                 if (mUseBpfStats) {
                     try {
                         requestSwapActiveStatsMapLocked();
                     } catch (RemoteException e) {
                         throw new IOException(e);
                     }
                     // Stats are always read from the inactive map, so they must be read after the
                     // swap
                     if (nativeReadNetworkStatsDetail(stats, mStatsXtUid.getAbsolutePath(), UID_ALL,
                             INTERFACES_ALL, TAG_ALL, mUseBpfStats) != 0) {
                         throw new IOException("Failed to parse network stats");
                     }

                     // BPF stats are incremental; fold into mPersistSnapshot.
                     mPersistSnapshot.setElapsedRealtime(stats.getElapsedRealtime());
                     mPersistSnapshot.combineAllValues(stats);
                 } else {
                     if (nativeReadNetworkStatsDetail(stats, mStatsXtUid.getAbsolutePath(), UID_ALL,
                             INTERFACES_ALL, TAG_ALL, mUseBpfStats) != 0) {
                         throw new IOException("Failed to parse network stats");
                     }
                     if (SANITY_CHECK_NATIVE) {
                         final NetworkStats javaStats = javaReadNetworkStatsDetail(mStatsXtUid,
                                 UID_ALL, INTERFACES_ALL, TAG_ALL);
                         assertEquals(javaStats, stats);
                     }

                     mPersistSnapshot = stats;
                 }
             } else {
                 mPersistSnapshot = javaReadNetworkStatsDetail(mStatsXtUid, UID_ALL, INTERFACES_ALL,
                         TAG_ALL);
             }

             NetworkStats adjustedStats = adjustForTunAnd464Xlat(mPersistSnapshot, prev, vpnArray);

             // Filter return values
             adjustedStats.filter(limitUid, limitIfaces, limitTag);
             return adjustedStats;
         }
     }

     @GuardedBy("mPersistentDataLock")
     private NetworkStats adjustForTunAnd464Xlat(
             NetworkStats uidDetailStats, NetworkStats previousStats, VpnInfo[] vpnArray) {
         // Calculate delta from last snapshot
         final NetworkStats delta = uidDetailStats.subtract(previousStats);

         // Apply 464xlat adjustments before VPN adjustments. If VPNs are using v4 on a v6 only
         // network, the overhead is their fault.
         // No locking here: apply464xlatAdjustments behaves fine with an add-only
         // ConcurrentHashMap.
         delta.apply464xlatAdjustments(mStackedIfaces, mUseBpfStats);

         // Migrate data usage over a VPN to the TUN network.
         for (VpnInfo info : vpnArray) {
             delta.migrateTun(info.ownerUid, info.vpnIface, info.underlyingIfaces);
         }

         // Filter out debug entries as that may lead to over counting.
         delta.filterDebugEntries();

         // Update mTunAnd464xlatAdjustedStats with migrated delta.
         mTunAnd464xlatAdjustedStats.combineAllValues(delta);
         mTunAnd464xlatAdjustedStats.setElapsedRealtime(uidDetailStats.getElapsedRealtime());

         return mTunAnd464xlatAdjustedStats.clone();
     }

     /**
      * Parse and return {@link NetworkStats} with UID-level details. Values are
      * expected to monotonically increase since device boot.
      */
     @VisibleForTesting
     public static NetworkStats javaReadNetworkStatsDetail(File detailPath, int limitUid,
             String[] limitIfaces, int limitTag)
             throws IOException {
         final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskReads();

         final NetworkStats stats = new NetworkStats(SystemClock.elapsedRealtime(), 24);
         final NetworkStats.Entry entry = new NetworkStats.Entry();

         int idx = 1;
         int lastIdx = 1;

         ProcFileReader reader = null;
         try {
             // open and consume header line
             reader = new ProcFileReader(new FileInputStream(detailPath));
             reader.finishLine();

             while (reader.hasMoreData()) {
                 idx = reader.nextInt();
                 if (idx != lastIdx + 1) {
                     throw new ProtocolException(
                             "inconsistent idx=" + idx + " after lastIdx=" + lastIdx);
                 }
                 lastIdx = idx;

                 entry.iface = reader.nextString();
                 entry.tag = kernelToTag(reader.nextString());
                 entry.uid = reader.nextInt();
                 entry.set = reader.nextInt();
                 entry.rxBytes = reader.nextLong();
                 entry.rxPackets = reader.nextLong();
                 entry.txBytes = reader.nextLong();
                 entry.txPackets = reader.nextLong();

                 if ((limitIfaces == null || ArrayUtils.contains(limitIfaces, entry.iface))
                         && (limitUid == UID_ALL || limitUid == entry.uid)
                         && (limitTag == TAG_ALL || limitTag == entry.tag)) {
                     stats.addEntry(entry);
                 }

                 reader.finishLine();
             }
         } catch (NullPointerException|NumberFormatException e) {
             throw protocolExceptionWithCause("problem parsing idx " + idx, e);
         } finally {
             IoUtils.closeQuietly(reader);
             StrictMode.setThreadPolicy(savedPolicy);
         }

         return stats;
     }

     public void assertEquals(NetworkStats expected, NetworkStats actual) {
         if (expected.size() != actual.size()) {
             throw new AssertionError(
                     "Expected size " + expected.size() + ", actual size " + actual.size());
         }

         NetworkStats.Entry expectedRow = null;
         NetworkStats.Entry actualRow = null;
         for (int i = 0; i < expected.size(); i++) {
             expectedRow = expected.getValues(i, expectedRow);
             actualRow = actual.getValues(i, actualRow);
             if (!expectedRow.equals(actualRow)) {
                 throw new AssertionError(
                         "Expected row " + i + ": " + expectedRow + ", actual row " + actualRow);
             }
         }
     }

     /**
      * Parse statistics from file into given {@link NetworkStats} object. Values
      * are expected to monotonically increase since device boot.
      */
     @VisibleForTesting
     public static native int nativeReadNetworkStatsDetail(NetworkStats stats, String path,
         int limitUid, String[] limitIfaces, int limitTag, boolean useBpfStats);

     @VisibleForTesting
     public static native int nativeReadNetworkStatsDev(NetworkStats stats);

     private static ProtocolException protocolExceptionWithCause(String message, Throwable cause) {
         ProtocolException pe = new ProtocolException(message);
         pe.initCause(cause);
         return pe;
     }
 }
	/*
	* Copyright (C) 2011 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.android.server.net;

	import static android.net.NetworkStats.INTERFACES_ALL;
	import static android.net.NetworkStats.SET_ALL;
	import static android.net.NetworkStats.TAG_ALL;
	import static android.net.NetworkStats.TAG_NONE;
	import static android.net.NetworkStats.UID_ALL;

	import static com.android.server.NetworkManagementSocketTagger.kernelToTag;

	import android.annotation.Nullable;
	import android.net.INetd;
	import android.net.NetworkStats;
	import android.net.util.NetdService;
	import android.os.RemoteException;
	import android.os.StrictMode;
	import android.os.SystemClock;

	import com.android.internal.annotations.GuardedBy;
	import com.android.internal.annotations.VisibleForTesting;
	import com.android.internal.net.VpnInfo;
	import com.android.internal.util.ArrayUtils;
	import com.android.internal.util.ProcFileReader;

	import libcore.io.IoUtils;

	import java.io.File;
	import java.io.FileInputStream;
	import java.io.IOException;
	import java.net.ProtocolException;
	import java.util.Arrays;
	import java.util.HashSet;
	import java.util.Map;
	import java.util.concurrent.ConcurrentHashMap;

	/**
	* Creates {@link NetworkStats} instances by parsing various {@code /proc/}
	* files as needed.
	*
	* @hide
	*/
	public class NetworkStatsFactory {
	private static final String TAG = "NetworkStatsFactory";

	private static final boolean USE_NATIVE_PARSING = true;
	private static final boolean SANITY_CHECK_NATIVE = false;

	/** Path to {@code /proc/net/xt_qtaguid/iface_stat_all}. */
	private final File mStatsXtIfaceAll;
	/** Path to {@code /proc/net/xt_qtaguid/iface_stat_fmt}. */
	private final File mStatsXtIfaceFmt;
	/** Path to {@code /proc/net/xt_qtaguid/stats}. */
	private final File mStatsXtUid;

	private final boolean mUseBpfStats;

	private INetd mNetdService;

	/**
	* Guards persistent data access in this class
	*
	* <p>In order to prevent deadlocks, critical sections protected by this lock SHALL NOT call out
	* to other code that will acquire other locks within the system server. See b/134244752.
	*/
	private final Object mPersistentDataLock = new Object();

	/** Set containing info about active VPNs and their underlying networks. */
	private volatile VpnInfo[] mVpnInfos = new VpnInfo[0];

	// A persistent snapshot of cumulative stats since device start
	@GuardedBy("mPersistentDataLock")
	private NetworkStats mPersistSnapshot;

	// The persistent snapshot of tun and 464xlat adjusted stats since device start
	@GuardedBy("mPersistentDataLock")
	private NetworkStats mTunAnd464xlatAdjustedStats;

	/**
	* (Stacked interface) -> (base interface) association for all connected ifaces since boot.
	*
	* Because counters must never roll backwards, once a given interface is stacked on top of an
	* underlying interface, the stacked interface can never be stacked on top of
	* another interface. */
	private final ConcurrentHashMap<String, String> mStackedIfaces
	= new ConcurrentHashMap<>();

	/** Informs the factory of a new stacked interface. */
	public void noteStackedIface(String stackedIface, String baseIface) {
	if (stackedIface != null && baseIface != null) {
	mStackedIfaces.put(stackedIface, baseIface);
	}
	}

	/**
	* Set active VPN information for data usage migration purposes
	*
	* <p>Traffic on TUN-based VPNs inherently all appear to be originated from the VPN providing
	* app's UID. This method is used to support migration of VPN data usage, ensuring data is
	* accurately billed to the real owner of the traffic.
	*
	* @param vpnArray The snapshot of the currently-running VPNs.
	*/
	public void updateVpnInfos(VpnInfo[] vpnArray) {
	mVpnInfos = vpnArray.clone();
	}

	/**
	* Get a set of interfaces containing specified ifaces and stacked interfaces.
	*
	* <p>The added stacked interfaces are ifaces stacked on top of the specified ones, or ifaces
	* on which the specified ones are stacked. Stacked interfaces are those noted with
	* {@link #noteStackedIface(String, String)}, but only interfaces noted before this method
	* is called are guaranteed to be included.
	*/
	public String[] augmentWithStackedInterfaces(@Nullable String[] requiredIfaces) {
	if (requiredIfaces == NetworkStats.INTERFACES_ALL) {
	return null;
	}

	HashSet<String> relatedIfaces = new HashSet<>(Arrays.asList(requiredIfaces));
	// ConcurrentHashMap's EntrySet iterators are "guaranteed to traverse
	// elements as they existed upon construction exactly once, and may
	// (but are not guaranteed to) reflect any modifications subsequent to construction".
	// This is enough here.
	for (Map.Entry<String, String> entry : mStackedIfaces.entrySet()) {
	if (relatedIfaces.contains(entry.getKey())) {
	relatedIfaces.add(entry.getValue());
	} else if (relatedIfaces.contains(entry.getValue())) {
	relatedIfaces.add(entry.getKey());
	}
	}

	String[] outArray = new String[relatedIfaces.size()];
	return relatedIfaces.toArray(outArray);
	}

	/**
	* Applies 464xlat adjustments with ifaces noted with {@link #noteStackedIface(String, String)}.
	* @see NetworkStats#apply464xlatAdjustments(NetworkStats, NetworkStats, Map, boolean)
	*/
	public void apply464xlatAdjustments(NetworkStats baseTraffic,
	NetworkStats stackedTraffic, boolean useBpfStats) {
	NetworkStats.apply464xlatAdjustments(baseTraffic, stackedTraffic, mStackedIfaces,
	useBpfStats);
	}

	public NetworkStatsFactory() {
	this(new File("/proc/"), new File("/sys/fs/bpf/map_netd_app_uid_stats_map").exists());
	}

	@VisibleForTesting
	public NetworkStatsFactory(File procRoot, boolean useBpfStats) {
	mStatsXtIfaceAll = new File(procRoot, "net/xt_qtaguid/iface_stat_all");
	mStatsXtIfaceFmt = new File(procRoot, "net/xt_qtaguid/iface_stat_fmt");
	mStatsXtUid = new File(procRoot, "net/xt_qtaguid/stats");
	mUseBpfStats = useBpfStats;
	synchronized (mPersistentDataLock) {
	mPersistSnapshot = new NetworkStats(SystemClock.elapsedRealtime(), -1);
	mTunAnd464xlatAdjustedStats = new NetworkStats(SystemClock.elapsedRealtime(), -1);
	}
	}

	public NetworkStats readBpfNetworkStatsDev() throws IOException {
	final NetworkStats stats = new NetworkStats(SystemClock.elapsedRealtime(), 6);
	if (nativeReadNetworkStatsDev(stats) != 0) {
	throw new IOException("Failed to parse bpf iface stats");
	}
	return stats;
	}

	/**
	* Parse and return interface-level summary {@link NetworkStats} measured
	* using {@code /proc/net/dev} style hooks, which may include non IP layer
	* traffic. Values monotonically increase since device boot, and may include
	* details about inactive interfaces.
	*
	* @throws IllegalStateException when problem parsing stats.
	*/
	public NetworkStats readNetworkStatsSummaryDev() throws IOException {

	// Return xt_bpf stats if switched to bpf module.
	if (mUseBpfStats)
	return readBpfNetworkStatsDev();

	final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskReads();

	final NetworkStats stats = new NetworkStats(SystemClock.elapsedRealtime(), 6);
	final NetworkStats.Entry entry = new NetworkStats.Entry();

	ProcFileReader reader = null;
	try {
	reader = new ProcFileReader(new FileInputStream(mStatsXtIfaceAll));

	while (reader.hasMoreData()) {
	entry.iface = reader.nextString();
	entry.uid = UID_ALL;
	entry.set = SET_ALL;
	entry.tag = TAG_NONE;

	final boolean active = reader.nextInt() != 0;

	// always include snapshot values
	entry.rxBytes = reader.nextLong();
	entry.rxPackets = reader.nextLong();
	entry.txBytes = reader.nextLong();
	entry.txPackets = reader.nextLong();

	// fold in active numbers, but only when active
	if (active) {
	entry.rxBytes += reader.nextLong();
	entry.rxPackets += reader.nextLong();
	entry.txBytes += reader.nextLong();
	entry.txPackets += reader.nextLong();
	}

	stats.addEntry(entry);
	reader.finishLine();
	}
	} catch (NullPointerException\|NumberFormatException e) {
	throw protocolExceptionWithCause("problem parsing stats", e);
	} finally {
	IoUtils.closeQuietly(reader);
	StrictMode.setThreadPolicy(savedPolicy);
	}
	return stats;
	}

	/**
	* Parse and return interface-level summary {@link NetworkStats}. Designed
	* to return only IP layer traffic. Values monotonically increase since
	* device boot, and may include details about inactive interfaces.
	*
	* @throws IllegalStateException when problem parsing stats.
	*/
	public NetworkStats readNetworkStatsSummaryXt() throws IOException {

	// Return xt_bpf stats if qtaguid module is replaced.
	if (mUseBpfStats)
	return readBpfNetworkStatsDev();

	final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskReads();

	// return null when kernel doesn't support
	if (!mStatsXtIfaceFmt.exists()) return null;

	final NetworkStats stats = new NetworkStats(SystemClock.elapsedRealtime(), 6);
	final NetworkStats.Entry entry = new NetworkStats.Entry();

	ProcFileReader reader = null;
	try {
	// open and consume header line
	reader = new ProcFileReader(new FileInputStream(mStatsXtIfaceFmt));
	reader.finishLine();

	while (reader.hasMoreData()) {
	entry.iface = reader.nextString();
	entry.uid = UID_ALL;
	entry.set = SET_ALL;
	entry.tag = TAG_NONE;

	entry.rxBytes = reader.nextLong();
	entry.rxPackets = reader.nextLong();
	entry.txBytes = reader.nextLong();
	entry.txPackets = reader.nextLong();

	stats.addEntry(entry);
	reader.finishLine();
	}
	} catch (NullPointerException\|NumberFormatException e) {
	throw protocolExceptionWithCause("problem parsing stats", e);
	} finally {
	IoUtils.closeQuietly(reader);
	StrictMode.setThreadPolicy(savedPolicy);
	}
	return stats;
	}

	public NetworkStats readNetworkStatsDetail() throws IOException {
	return readNetworkStatsDetail(UID_ALL, INTERFACES_ALL, TAG_ALL);
	}

	@GuardedBy("mPersistentDataLock")
	private void requestSwapActiveStatsMapLocked() throws RemoteException {
	// Ask netd to do a active map stats swap. When the binder call successfully returns,
	// the system server should be able to safely read and clean the inactive map
	// without race problem.
	if (mNetdService == null) {
	mNetdService = NetdService.getInstance();
	}
	mNetdService.trafficSwapActiveStatsMap();
	}

	/**
	* Reads the detailed UID stats based on the provided parameters
	*
	* @param limitUid the UID to limit this query to
	* @param limitIfaces the interfaces to limit this query to. Use {@link
	* NetworkStats.INTERFACES_ALL} to select all interfaces
	* @param limitTag the tags to limit this query to
	* @return the NetworkStats instance containing network statistics at the present time.
	*/
	public NetworkStats readNetworkStatsDetail(
	int limitUid, String[] limitIfaces, int limitTag) throws IOException {
	// In order to prevent deadlocks, anything protected by this lock MUST NOT call out to other
	// code that will acquire other locks within the system server. See b/134244752.
	synchronized (mPersistentDataLock) {
	// Take a reference. If this gets swapped out, we still have the old reference.
	final VpnInfo[] vpnArray = mVpnInfos;
	// Take a defensive copy. mPersistSnapshot is mutated in some cases below
	final NetworkStats prev = mPersistSnapshot.clone();

	if (USE_NATIVE_PARSING) {
	final NetworkStats stats =
	new NetworkStats(SystemClock.elapsedRealtime(), 0 /* initialSize */);
	if (mUseBpfStats) {
	try {
	requestSwapActiveStatsMapLocked();
	} catch (RemoteException e) {
	throw new IOException(e);
	}
	// Stats are always read from the inactive map, so they must be read after the
	// swap
	if (nativeReadNetworkStatsDetail(stats, mStatsXtUid.getAbsolutePath(), UID_ALL,
	INTERFACES_ALL, TAG_ALL, mUseBpfStats) != 0) {
	throw new IOException("Failed to parse network stats");
	}

	// BPF stats are incremental; fold into mPersistSnapshot.
	mPersistSnapshot.setElapsedRealtime(stats.getElapsedRealtime());
	mPersistSnapshot.combineAllValues(stats);
	} else {
	if (nativeReadNetworkStatsDetail(stats, mStatsXtUid.getAbsolutePath(), UID_ALL,
	INTERFACES_ALL, TAG_ALL, mUseBpfStats) != 0) {
	throw new IOException("Failed to parse network stats");
	}
	if (SANITY_CHECK_NATIVE) {
	final NetworkStats javaStats = javaReadNetworkStatsDetail(mStatsXtUid,
	UID_ALL, INTERFACES_ALL, TAG_ALL);
	assertEquals(javaStats, stats);
	}

	mPersistSnapshot = stats;
	}
	} else {
	mPersistSnapshot = javaReadNetworkStatsDetail(mStatsXtUid, UID_ALL, INTERFACES_ALL,
	TAG_ALL);
	}

	NetworkStats adjustedStats = adjustForTunAnd464Xlat(mPersistSnapshot, prev, vpnArray);

	// Filter return values
	adjustedStats.filter(limitUid, limitIfaces, limitTag);
	return adjustedStats;
	}
	}

	@GuardedBy("mPersistentDataLock")
	private NetworkStats adjustForTunAnd464Xlat(
	NetworkStats uidDetailStats, NetworkStats previousStats, VpnInfo[] vpnArray) {
	// Calculate delta from last snapshot
	final NetworkStats delta = uidDetailStats.subtract(previousStats);

	// Apply 464xlat adjustments before VPN adjustments. If VPNs are using v4 on a v6 only
	// network, the overhead is their fault.
	// No locking here: apply464xlatAdjustments behaves fine with an add-only
	// ConcurrentHashMap.
	delta.apply464xlatAdjustments(mStackedIfaces, mUseBpfStats);

	// Migrate data usage over a VPN to the TUN network.
	for (VpnInfo info : vpnArray) {
	delta.migrateTun(info.ownerUid, info.vpnIface, info.underlyingIfaces);
	}

	// Filter out debug entries as that may lead to over counting.
	delta.filterDebugEntries();

	// Update mTunAnd464xlatAdjustedStats with migrated delta.
	mTunAnd464xlatAdjustedStats.combineAllValues(delta);
	mTunAnd464xlatAdjustedStats.setElapsedRealtime(uidDetailStats.getElapsedRealtime());

	return mTunAnd464xlatAdjustedStats.clone();
	}

	/**
	* Parse and return {@link NetworkStats} with UID-level details. Values are
	* expected to monotonically increase since device boot.
	*/
	@VisibleForTesting
	public static NetworkStats javaReadNetworkStatsDetail(File detailPath, int limitUid,
	String[] limitIfaces, int limitTag)
	throws IOException {
	final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskReads();

	final NetworkStats stats = new NetworkStats(SystemClock.elapsedRealtime(), 24);
	final NetworkStats.Entry entry = new NetworkStats.Entry();

	int idx = 1;
	int lastIdx = 1;

	ProcFileReader reader = null;
	try {
	// open and consume header line
	reader = new ProcFileReader(new FileInputStream(detailPath));
	reader.finishLine();

	while (reader.hasMoreData()) {
	idx = reader.nextInt();
	if (idx != lastIdx + 1) {
	throw new ProtocolException(
	"inconsistent idx=" + idx + " after lastIdx=" + lastIdx);
	}
	lastIdx = idx;

	entry.iface = reader.nextString();
	entry.tag = kernelToTag(reader.nextString());
	entry.uid = reader.nextInt();
	entry.set = reader.nextInt();
	entry.rxBytes = reader.nextLong();
	entry.rxPackets = reader.nextLong();
	entry.txBytes = reader.nextLong();
	entry.txPackets = reader.nextLong();

	if ((limitIfaces == null \|\| ArrayUtils.contains(limitIfaces, entry.iface))
	&& (limitUid == UID_ALL \|\| limitUid == entry.uid)
	&& (limitTag == TAG_ALL \|\| limitTag == entry.tag)) {
	stats.addEntry(entry);
	}

	reader.finishLine();
	}
	} catch (NullPointerException\|NumberFormatException e) {
	throw protocolExceptionWithCause("problem parsing idx " + idx, e);
	} finally {
	IoUtils.closeQuietly(reader);
	StrictMode.setThreadPolicy(savedPolicy);
	}

	return stats;
	}

	public void assertEquals(NetworkStats expected, NetworkStats actual) {
	if (expected.size() != actual.size()) {
	throw new AssertionError(
	"Expected size " + expected.size() + ", actual size " + actual.size());
	}

	NetworkStats.Entry expectedRow = null;
	NetworkStats.Entry actualRow = null;
	for (int i = 0; i < expected.size(); i++) {
	expectedRow = expected.getValues(i, expectedRow);
	actualRow = actual.getValues(i, actualRow);
	if (!expectedRow.equals(actualRow)) {
	throw new AssertionError(
	"Expected row " + i + ": " + expectedRow + ", actual row " + actualRow);
	}
	}
	}

	/**
	* Parse statistics from file into given {@link NetworkStats} object. Values
	* are expected to monotonically increase since device boot.
	*/
	@VisibleForTesting
	public static native int nativeReadNetworkStatsDetail(NetworkStats stats, String path,
	int limitUid, String[] limitIfaces, int limitTag, boolean useBpfStats);

	@VisibleForTesting
	public static native int nativeReadNetworkStatsDev(NetworkStats stats);

	private static ProtocolException protocolExceptionWithCause(String message, Throwable cause) {
	ProtocolException pe = new ProtocolException(message);
	pe.initCause(cause);
	return pe;
	}
	}