src/android/net/apf/ApfCounterTracker.java - platform/packages/modules/NetworkStack - Git at Google

 /*
  * Copyright (C) 2023 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 android.net.apf;

 import static android.net.apf.ApfCounterTracker.Counter.APF_PROGRAM_ID;
 import static android.net.apf.ApfCounterTracker.Counter.FILTER_AGE_SECONDS;

 import android.annotation.NonNull;
 import android.util.ArrayMap;
 import android.util.Log;
 import android.util.Pair;

 import com.android.internal.annotations.VisibleForTesting;

 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;

 /**
  * Counter class for {@code ApfFilter}.
  *
  * @hide
  */
 public class ApfCounterTracker {
     /**
      * APF packet counters.
      *
      * Packet counters are 32bit big-endian values, and allocated near the end of the APF data
      * buffer, using negative byte offsets, where -4 is equivalent to maximumApfProgramSize - 4,
      * the last writable 32bit word.
      */
     public enum Counter {
         RESERVED_OOB,  // Points to offset 0 from the end of the buffer (out-of-bounds)
         ENDIANNESS,              // APFv6 interpreter stores 0x12345678 here
         TOTAL_PACKETS,           // hardcoded in APFv6 interpreter
         PASSED_ALLOCATE_FAILURE, // hardcoded in APFv6 interpreter
         PASSED_TRANSMIT_FAILURE, // hardcoded in APFv6 interpreter
         CORRUPT_DNS_PACKET,      // hardcoded in APFv6 interpreter
         EXCEPTIONS,              // hardcoded in APFv6.1 interpreter
         FILTER_AGE_SECONDS,
         FILTER_AGE_16384THS,
         APF_VERSION,
         APF_PROGRAM_ID,
         // The counter sequence should keep the same as ApfSessionInfoMetrics.java
         PASSED_ARP_BROADCAST_REPLY,  // see also MIN_PASS_COUNTER below.
         PASSED_ARP_REQUEST,
         PASSED_ARP_UNICAST_REPLY,
         PASSED_DHCP,
         PASSED_DUE_TO_REPLY_OVER_MTU,
         PASSED_ETHER_OUR_SRC_MAC,
         PASSED_IPV4,
         PASSED_IPV4_FROM_DHCPV4_SERVER,
         PASSED_IPV4_UNICAST,
         PASSED_IPV6_HOPOPTS,
         PASSED_IPV6_ICMP,
         PASSED_IPV6_NON_ICMP,
         PASSED_IPV6_UNICAST_NON_ICMP,
         PASSED_NON_IP_UNICAST,
         PASSED_MDNS,
         PASSED_RA, // see also MAX_PASS_COUNTER below
         DROPPED_ETH_BROADCAST,  // see also MIN_DROP_COUNTER below
         DROPPED_ETHER_OUR_SRC_MAC,
         DROPPED_RA,
         DROPPED_IPV4_L2_BROADCAST,
         DROPPED_IPV4_BROADCAST_ADDR,
         DROPPED_IPV4_BROADCAST_NET,
         DROPPED_IPV4_ICMP_INVALID,
         DROPPED_IPV4_MULTICAST,
         DROPPED_IPV4_NON_DHCP4,
         DROPPED_IPV4_PING_REQUEST_REPLIED,
         DROPPED_IPV6_ICMP6_ECHO_REQUEST_INVALID,
         DROPPED_IPV6_ICMP6_ECHO_REQUEST_REPLIED,
         DROPPED_IPV6_ROUTER_SOLICITATION,
         DROPPED_IPV6_MLD_INVALID,
         DROPPED_IPV6_MLD_REPORT,
         DROPPED_IPV6_MLD_V1_GENERAL_QUERY_REPLIED,
         DROPPED_IPV6_MLD_V2_GENERAL_QUERY_REPLIED,
         DROPPED_IPV6_MULTICAST_NA,
         DROPPED_IPV6_NON_ICMP_MULTICAST,
         DROPPED_IPV6_NS_INVALID,
         DROPPED_IPV6_NS_OTHER_HOST,
         DROPPED_IPV6_NS_REPLIED_NON_DAD,
         DROPPED_802_3_FRAME,
         DROPPED_ETHERTYPE_NOT_ALLOWED,
         DROPPED_IPV4_KEEPALIVE_ACK,
         DROPPED_IPV4_NATT_KEEPALIVE,
         DROPPED_MDNS,
         DROPPED_MDNS_REPLIED,
         DROPPED_NON_UNICAST_TDLS,
         DROPPED_IPV4_TCP_PORT7_UNICAST,
         DROPPED_ARP_NON_IPV4,
         DROPPED_ARP_OTHER_HOST,
         DROPPED_ARP_REPLY_SPA_NO_HOST,
         DROPPED_ARP_REQUEST_REPLIED,
         DROPPED_ARP_UNKNOWN,
         DROPPED_ARP_V6_ONLY,
         DROPPED_IGMP_V2_GENERAL_QUERY_REPLIED,
         DROPPED_IGMP_V3_GENERAL_QUERY_REPLIED,
         DROPPED_IGMP_INVALID,
         DROPPED_IGMP_REPORT,
         DROPPED_GARP_REPLY;  // see also MAX_DROP_COUNTER below

         /**
          * Returns the negative byte offset from the end of the APF data segment for
          * a given counter.
          */
         public int offset() {
             return -this.value() * 4;  // Currently, all counters are 32bit long.
         }

         /**
          * Returns the counter sequence number from the end of the APF data segment for
          * a given counter.
          */
         public int value() {
             return this.ordinal();
         }

         /**
          * Returns the total size of the data segment in bytes.
          */
         public static int totalSize() {
             return (Counter.class.getEnumConstants().length - 1) * 4;
         }

         /**
          * Returns the counter enum based on the offset.
          */
         @VisibleForTesting(visibility = VisibleForTesting.Visibility.PACKAGE)
         public static Counter getCounterEnumFromOffset(int offset) {
             for (Counter cnt : Counter.class.getEnumConstants()) {
                 if (cnt.offset() == offset) {
                     return cnt;
                 }
             }
             return RESERVED_OOB;
         }

         private void checkCounterRange(Counter lowerBound, Counter upperBound) {
             if (value() < lowerBound.value() || value() > upperBound.value()) {
                 throw new IllegalArgumentException(
                         String.format("Counter %s, is not in range [%s, %s]", this,
                                 lowerBound, upperBound));
             }
         }

         /**
          * Return the label such that if we jump to it, the counter will be increased by 1 and
          * the packet will be passed.
          */
         public short getJumpPassLabel() {
             checkCounterRange(MIN_PASS_COUNTER, MAX_PASS_COUNTER);
             return (short) (2 * this.value());
         }

         /**
          * Return the label such that if we jump to it, the counter will be increased by 1 and
          * the packet will be dropped.
          */
         public short getJumpDropLabel() {
             checkCounterRange(MIN_DROP_COUNTER, MAX_DROP_COUNTER);
             return (short) (2 * this.value() + 1);
         }
     }

     public static final Counter MIN_DROP_COUNTER = Counter.DROPPED_ETH_BROADCAST;
     public static final Counter MAX_DROP_COUNTER = Counter.DROPPED_GARP_REPLY;
     public static final Counter MIN_PASS_COUNTER = Counter.PASSED_ARP_BROADCAST_REPLY;
     public static final Counter MAX_PASS_COUNTER = Counter.PASSED_RA;

     private static final String TAG = ApfCounterTracker.class.getSimpleName();

     private final List<Counter> mCounterList;
     // Store the counters' value
     private final Map<Counter, Long> mCounters = new ArrayMap<>();

     public ApfCounterTracker() {
         Counter[] counters = Counter.class.getEnumConstants();
         mCounterList = Arrays.asList(counters).subList(1, counters.length);
     }

     /**
      * Get the value of a counter from APF data.
      */
     public static long getCounterValue(byte[] data, Counter counter)
             throws ArrayIndexOutOfBoundsException {
         int offset = data.length + Counter.ENDIANNESS.offset();
         int endianness = 0;
         for (int i = 0; i < 4; i++) {
             endianness = endianness << 8 | (data[offset + i] & 0xff);
         }
         // Follow the same wrap-around addressing scheme of the interpreter.
         offset = data.length + counter.offset();

         boolean isBe = true;
         switch (endianness) {
             case 0:
             case 0x12345678:
                 isBe = true;
                 break;
             case 0x78563412:
                 isBe = false;
                 break;
             default:
                 Log.wtf(TAG, "Unknown endianness: 0x" + Integer.toHexString(endianness));
         }

         // Decode 32bit big-endian integer into a long so we can count up beyond 2^31.
         long value = 0;
         for (int i = 0; i < 4; i++) {
             value = value << 8 | (data[offset + (isBe ? i : 3 - i)] & 0xff);
         }
         return value;
     }

     /**
      * Update counters from APF data.
      */
     public void updateCountersFromData(byte[] data) {
         if (data == null) return;
         for (Counter counter : mCounterList) {
             long value;
             try {
                 value = getCounterValue(data, counter);
             } catch (ArrayIndexOutOfBoundsException e) {
                 value = 0;
             }
             long oldValue = mCounters.getOrDefault(counter, 0L);
             // All counters are incremental
             if (value > oldValue) {
                 mCounters.put(counter, value);
             }
         }
     }

     /**
      * Get counters map.
      */
     public Map<Counter, Long> getCounters() {
         return mCounters;
     }

     /**
      * Clear all counters.
      */
     public void clearCounters() {
         mCounters.clear();
     }

     /**
      * Return readable counter for testing purposes.
      */
     public List<Pair<Counter, String>> dumpCountersFromData(
             @NonNull byte[] data,
             int filterAgeSeconds,
             int numProgramUpdates,
             int apfVersionSupported) throws ArrayIndexOutOfBoundsException {
         List<Pair<Counter, String>> counterList = new ArrayList<>();
         Counter[] counters = Counter.class.getEnumConstants();
         long counterFilterAgeSeconds =
                 getCounterValue(data, FILTER_AGE_SECONDS);
         long counterApfProgramId =
                 getCounterValue(data, APF_PROGRAM_ID);

         for (Counter c : Arrays.asList(counters).subList(1, counters.length)) {
             long value = getCounterValue(data, c);

             String note = "";
             boolean checkValueIncreases = true;
             switch (c) {
                 case FILTER_AGE_SECONDS:
                     checkValueIncreases = false;
                     if (value != counterFilterAgeSeconds) {
                         note = " [ERROR: impossible]";
                     } else if (counterApfProgramId < numProgramUpdates) {
                         note = " [IGNORE: obsolete program]";
                     } else if (value > filterAgeSeconds) {
                         long offset = value - filterAgeSeconds;
                         note = " [ERROR: in the future by " + offset + "s]";
                     }
                     break;
                 case FILTER_AGE_16384THS:
                     if (apfVersionSupported > BaseApfGenerator.APF_VERSION_4) {
                         checkValueIncreases = false;
                         if (value % 16384 == 0) {
                             // valid, but unlikely
                             note = " [INFO: zero fractional portion]";
                         }
                         if (value / 16384 != counterFilterAgeSeconds) {
                             // should not be able to happen
                             note = " [ERROR: mismatch with FILTER_AGE_SECONDS]";
                         }
                     } else if (value != 0) {
                         note = " [UNEXPECTED: APF<=4, yet non-zero]";
                     }
                     break;
                 case APF_PROGRAM_ID:
                     if (value != counterApfProgramId) {
                         note = " [ERROR: impossible]";
                     } else if (value < numProgramUpdates) {
                         note = " [WARNING: OBSOLETE PROGRAM]";
                     } else if (value > numProgramUpdates) {
                         note = " [ERROR: INVALID FUTURE ID]";
                     }
                     break;
                 default:
                     break;
             }

             // Only print non-zero counters (or those with a note)
             if (value != 0 || !note.equals("")) {
                 counterList.add(new Pair<>(c, value + note));
             }

             if (checkValueIncreases) {
                 // If the counter's value decreases, it may have been cleaned up or there
                 // may be a bug.
                 long oldValue = getCounters().getOrDefault(c, 0L);
                 if (value < oldValue) {
                     Log.e(TAG, String.format(
                             "Apf Counter: %s unexpectedly decreased. oldValue: %d. "
                             + "newValue: %d", c.toString(), oldValue, value));
                 }
             }
         }

         return counterList;
     }
 }
	/*
	* Copyright (C) 2023 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 android.net.apf;

	import static android.net.apf.ApfCounterTracker.Counter.APF_PROGRAM_ID;
	import static android.net.apf.ApfCounterTracker.Counter.FILTER_AGE_SECONDS;

	import android.annotation.NonNull;
	import android.util.ArrayMap;
	import android.util.Log;
	import android.util.Pair;

	import com.android.internal.annotations.VisibleForTesting;

	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.List;
	import java.util.Map;

	/**
	* Counter class for {@code ApfFilter}.
	*
	* @hide
	*/
	public class ApfCounterTracker {
	/**
	* APF packet counters.
	*
	* Packet counters are 32bit big-endian values, and allocated near the end of the APF data
	* buffer, using negative byte offsets, where -4 is equivalent to maximumApfProgramSize - 4,
	* the last writable 32bit word.
	*/
	public enum Counter {
	RESERVED_OOB, // Points to offset 0 from the end of the buffer (out-of-bounds)
	ENDIANNESS, // APFv6 interpreter stores 0x12345678 here
	TOTAL_PACKETS, // hardcoded in APFv6 interpreter
	PASSED_ALLOCATE_FAILURE, // hardcoded in APFv6 interpreter
	PASSED_TRANSMIT_FAILURE, // hardcoded in APFv6 interpreter
	CORRUPT_DNS_PACKET, // hardcoded in APFv6 interpreter
	EXCEPTIONS, // hardcoded in APFv6.1 interpreter
	FILTER_AGE_SECONDS,
	FILTER_AGE_16384THS,
	APF_VERSION,
	APF_PROGRAM_ID,
	// The counter sequence should keep the same as ApfSessionInfoMetrics.java
	PASSED_ARP_BROADCAST_REPLY, // see also MIN_PASS_COUNTER below.
	PASSED_ARP_REQUEST,
	PASSED_ARP_UNICAST_REPLY,
	PASSED_DHCP,
	PASSED_DUE_TO_REPLY_OVER_MTU,
	PASSED_ETHER_OUR_SRC_MAC,
	PASSED_IPV4,
	PASSED_IPV4_FROM_DHCPV4_SERVER,
	PASSED_IPV4_UNICAST,
	PASSED_IPV6_HOPOPTS,
	PASSED_IPV6_ICMP,
	PASSED_IPV6_NON_ICMP,
	PASSED_IPV6_UNICAST_NON_ICMP,
	PASSED_NON_IP_UNICAST,
	PASSED_MDNS,
	PASSED_RA, // see also MAX_PASS_COUNTER below
	DROPPED_ETH_BROADCAST, // see also MIN_DROP_COUNTER below
	DROPPED_ETHER_OUR_SRC_MAC,
	DROPPED_RA,
	DROPPED_IPV4_L2_BROADCAST,
	DROPPED_IPV4_BROADCAST_ADDR,
	DROPPED_IPV4_BROADCAST_NET,
	DROPPED_IPV4_ICMP_INVALID,
	DROPPED_IPV4_MULTICAST,
	DROPPED_IPV4_NON_DHCP4,
	DROPPED_IPV4_PING_REQUEST_REPLIED,
	DROPPED_IPV6_ICMP6_ECHO_REQUEST_INVALID,
	DROPPED_IPV6_ICMP6_ECHO_REQUEST_REPLIED,
	DROPPED_IPV6_ROUTER_SOLICITATION,
	DROPPED_IPV6_MLD_INVALID,
	DROPPED_IPV6_MLD_REPORT,
	DROPPED_IPV6_MLD_V1_GENERAL_QUERY_REPLIED,
	DROPPED_IPV6_MLD_V2_GENERAL_QUERY_REPLIED,
	DROPPED_IPV6_MULTICAST_NA,
	DROPPED_IPV6_NON_ICMP_MULTICAST,
	DROPPED_IPV6_NS_INVALID,
	DROPPED_IPV6_NS_OTHER_HOST,
	DROPPED_IPV6_NS_REPLIED_NON_DAD,
	DROPPED_802_3_FRAME,
	DROPPED_ETHERTYPE_NOT_ALLOWED,
	DROPPED_IPV4_KEEPALIVE_ACK,
	DROPPED_IPV4_NATT_KEEPALIVE,
	DROPPED_MDNS,
	DROPPED_MDNS_REPLIED,
	DROPPED_NON_UNICAST_TDLS,
	DROPPED_IPV4_TCP_PORT7_UNICAST,
	DROPPED_ARP_NON_IPV4,
	DROPPED_ARP_OTHER_HOST,
	DROPPED_ARP_REPLY_SPA_NO_HOST,
	DROPPED_ARP_REQUEST_REPLIED,
	DROPPED_ARP_UNKNOWN,
	DROPPED_ARP_V6_ONLY,
	DROPPED_IGMP_V2_GENERAL_QUERY_REPLIED,
	DROPPED_IGMP_V3_GENERAL_QUERY_REPLIED,
	DROPPED_IGMP_INVALID,
	DROPPED_IGMP_REPORT,
	DROPPED_GARP_REPLY; // see also MAX_DROP_COUNTER below

	/**
	* Returns the negative byte offset from the end of the APF data segment for
	* a given counter.
	*/
	public int offset() {
	return -this.value() * 4; // Currently, all counters are 32bit long.
	}

	/**
	* Returns the counter sequence number from the end of the APF data segment for
	* a given counter.
	*/
	public int value() {
	return this.ordinal();
	}

	/**
	* Returns the total size of the data segment in bytes.
	*/
	public static int totalSize() {
	return (Counter.class.getEnumConstants().length - 1) * 4;
	}

	/**
	* Returns the counter enum based on the offset.
	*/
	@VisibleForTesting(visibility = VisibleForTesting.Visibility.PACKAGE)
	public static Counter getCounterEnumFromOffset(int offset) {
	for (Counter cnt : Counter.class.getEnumConstants()) {
	if (cnt.offset() == offset) {
	return cnt;
	}
	}
	return RESERVED_OOB;
	}

	private void checkCounterRange(Counter lowerBound, Counter upperBound) {
	if (value() < lowerBound.value() \|\| value() > upperBound.value()) {
	throw new IllegalArgumentException(
	String.format("Counter %s, is not in range [%s, %s]", this,
	lowerBound, upperBound));
	}
	}

	/**
	* Return the label such that if we jump to it, the counter will be increased by 1 and
	* the packet will be passed.
	*/
	public short getJumpPassLabel() {
	checkCounterRange(MIN_PASS_COUNTER, MAX_PASS_COUNTER);
	return (short) (2 * this.value());
	}

	/**
	* Return the label such that if we jump to it, the counter will be increased by 1 and
	* the packet will be dropped.
	*/
	public short getJumpDropLabel() {
	checkCounterRange(MIN_DROP_COUNTER, MAX_DROP_COUNTER);
	return (short) (2 * this.value() + 1);
	}
	}

	public static final Counter MIN_DROP_COUNTER = Counter.DROPPED_ETH_BROADCAST;
	public static final Counter MAX_DROP_COUNTER = Counter.DROPPED_GARP_REPLY;
	public static final Counter MIN_PASS_COUNTER = Counter.PASSED_ARP_BROADCAST_REPLY;
	public static final Counter MAX_PASS_COUNTER = Counter.PASSED_RA;

	private static final String TAG = ApfCounterTracker.class.getSimpleName();

	private final List<Counter> mCounterList;
	// Store the counters' value
	private final Map<Counter, Long> mCounters = new ArrayMap<>();

	public ApfCounterTracker() {
	Counter[] counters = Counter.class.getEnumConstants();
	mCounterList = Arrays.asList(counters).subList(1, counters.length);
	}

	/**
	* Get the value of a counter from APF data.
	*/
	public static long getCounterValue(byte[] data, Counter counter)
	throws ArrayIndexOutOfBoundsException {
	int offset = data.length + Counter.ENDIANNESS.offset();
	int endianness = 0;
	for (int i = 0; i < 4; i++) {
	endianness = endianness << 8 \| (data[offset + i] & 0xff);
	}
	// Follow the same wrap-around addressing scheme of the interpreter.
	offset = data.length + counter.offset();

	boolean isBe = true;
	switch (endianness) {
	case 0:
	case 0x12345678:
	isBe = true;
	break;
	case 0x78563412:
	isBe = false;
	break;
	default:
	Log.wtf(TAG, "Unknown endianness: 0x" + Integer.toHexString(endianness));
	}

	// Decode 32bit big-endian integer into a long so we can count up beyond 2^31.
	long value = 0;
	for (int i = 0; i < 4; i++) {
	value = value << 8 \| (data[offset + (isBe ? i : 3 - i)] & 0xff);
	}
	return value;
	}

	/**
	* Update counters from APF data.
	*/
	public void updateCountersFromData(byte[] data) {
	if (data == null) return;
	for (Counter counter : mCounterList) {
	long value;
	try {
	value = getCounterValue(data, counter);
	} catch (ArrayIndexOutOfBoundsException e) {
	value = 0;
	}
	long oldValue = mCounters.getOrDefault(counter, 0L);
	// All counters are incremental
	if (value > oldValue) {
	mCounters.put(counter, value);
	}
	}
	}

	/**
	* Get counters map.
	*/
	public Map<Counter, Long> getCounters() {
	return mCounters;
	}

	/**
	* Clear all counters.
	*/
	public void clearCounters() {
	mCounters.clear();
	}

	/**
	* Return readable counter for testing purposes.
	*/
	public List<Pair<Counter, String>> dumpCountersFromData(
	@NonNull byte[] data,
	int filterAgeSeconds,
	int numProgramUpdates,
	int apfVersionSupported) throws ArrayIndexOutOfBoundsException {
	List<Pair<Counter, String>> counterList = new ArrayList<>();
	Counter[] counters = Counter.class.getEnumConstants();
	long counterFilterAgeSeconds =
	getCounterValue(data, FILTER_AGE_SECONDS);
	long counterApfProgramId =
	getCounterValue(data, APF_PROGRAM_ID);

	for (Counter c : Arrays.asList(counters).subList(1, counters.length)) {
	long value = getCounterValue(data, c);

	String note = "";
	boolean checkValueIncreases = true;
	switch (c) {
	case FILTER_AGE_SECONDS:
	checkValueIncreases = false;
	if (value != counterFilterAgeSeconds) {
	note = " [ERROR: impossible]";
	} else if (counterApfProgramId < numProgramUpdates) {
	note = " [IGNORE: obsolete program]";
	} else if (value > filterAgeSeconds) {
	long offset = value - filterAgeSeconds;
	note = " [ERROR: in the future by " + offset + "s]";
	}
	break;
	case FILTER_AGE_16384THS:
	if (apfVersionSupported > BaseApfGenerator.APF_VERSION_4) {
	checkValueIncreases = false;
	if (value % 16384 == 0) {
	// valid, but unlikely
	note = " [INFO: zero fractional portion]";
	}
	if (value / 16384 != counterFilterAgeSeconds) {
	// should not be able to happen
	note = " [ERROR: mismatch with FILTER_AGE_SECONDS]";
	}
	} else if (value != 0) {
	note = " [UNEXPECTED: APF<=4, yet non-zero]";
	}
	break;
	case APF_PROGRAM_ID:
	if (value != counterApfProgramId) {
	note = " [ERROR: impossible]";
	} else if (value < numProgramUpdates) {
	note = " [WARNING: OBSOLETE PROGRAM]";
	} else if (value > numProgramUpdates) {
	note = " [ERROR: INVALID FUTURE ID]";
	}
	break;
	default:
	break;
	}

	// Only print non-zero counters (or those with a note)
	if (value != 0 \|\| !note.equals("")) {
	counterList.add(new Pair<>(c, value + note));
	}

	if (checkValueIncreases) {
	// If the counter's value decreases, it may have been cleaned up or there
	// may be a bug.
	long oldValue = getCounters().getOrDefault(c, 0L);
	if (value < oldValue) {
	Log.e(TAG, String.format(
	"Apf Counter: %s unexpectedly decreased. oldValue: %d. "
	+ "newValue: %d", c.toString(), oldValue, value));
	}
	}
	}

	return counterList;
	}
	}