Merge changes from topic "fix-mdns" into main

* changes:
  [mdns] add tests for verifying address of mDNS reply
  [mdns] fix wrong NSEC answer for unique RRs
  [mdns] fix duplicated records for multiple questions
diff --git a/service-t/src/com/android/server/connectivity/mdns/MdnsRecordRepository.java b/service-t/src/com/android/server/connectivity/mdns/MdnsRecordRepository.java
index d46a7b5..f9951a9 100644
--- a/service-t/src/com/android/server/connectivity/mdns/MdnsRecordRepository.java
+++ b/service-t/src/com/android/server/connectivity/mdns/MdnsRecordRepository.java
@@ -46,6 +46,7 @@
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.Iterator;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -140,6 +141,9 @@
          * Last time (as per SystemClock.elapsedRealtime) when sent via unicast or multicast,
          * 0 if never
          */
+        // FIXME: the `lastSentTimeMs` and `lastAdvertisedTimeMs` should be maintained separately
+        // for IPv4 and IPv6, because neither IPv4 nor and IPv6 clients can receive replies in
+        // different address space.
         public long lastSentTimeMs;
 
         RecordInfo(NsdServiceInfo serviceInfo, T record, boolean sharedName) {
@@ -497,13 +501,17 @@
     public MdnsReplyInfo getReply(MdnsPacket packet, InetSocketAddress src) {
         final long now = SystemClock.elapsedRealtime();
         final boolean replyUnicast = (packet.flags & MdnsConstants.QCLASS_UNICAST) != 0;
-        final ArrayList<MdnsRecord> additionalAnswerRecords = new ArrayList<>();
-        final ArrayList<RecordInfo<?>> answerInfo = new ArrayList<>();
+
+        // Use LinkedHashSet for preserving the insert order of the RRs, so that RRs of the same
+        // service or host are grouped together (which is more developer-friendly).
+        final Set<RecordInfo<?>> answerInfo = new LinkedHashSet<>();
+        final Set<RecordInfo<?>> additionalAnswerInfo = new LinkedHashSet<>();
+
         for (MdnsRecord question : packet.questions) {
             // Add answers from general records
             addReplyFromService(question, mGeneralRecords, null /* servicePtrRecord */,
                     null /* serviceSrvRecord */, null /* serviceTxtRecord */, replyUnicast, now,
-                    answerInfo, additionalAnswerRecords, Collections.emptyList());
+                    answerInfo, additionalAnswerInfo, Collections.emptyList());
 
             // Add answers from each service
             for (int i = 0; i < mServices.size(); i++) {
@@ -511,13 +519,33 @@
                 if (registration.exiting || registration.isProbing) continue;
                 if (addReplyFromService(question, registration.allRecords, registration.ptrRecords,
                         registration.srvRecord, registration.txtRecord, replyUnicast, now,
-                        answerInfo, additionalAnswerRecords, packet.answers)) {
+                        answerInfo, additionalAnswerInfo, packet.answers)) {
                     registration.repliedServiceCount++;
                     registration.sentPacketCount++;
                 }
             }
         }
 
+        // If any record was already in the answer section, remove it from the additional answer
+        // section. This can typically happen when there are both queries for
+        // SRV / TXT / A / AAAA and PTR (which can cause SRV / TXT / A / AAAA records being added
+        // to the additional answer section).
+        additionalAnswerInfo.removeAll(answerInfo);
+
+        final List<MdnsRecord> additionalAnswerRecords =
+                new ArrayList<>(additionalAnswerInfo.size());
+        for (RecordInfo<?> info : additionalAnswerInfo) {
+            additionalAnswerRecords.add(info.record);
+        }
+
+        // RFC6762 6.1: negative responses
+        // "On receipt of a question for a particular name, rrtype, and rrclass, for which a
+        // responder does have one or more unique answers, the responder MAY also include an NSEC
+        // record in the Additional Record Section indicating the nonexistence of other rrtypes
+        // for that name and rrclass."
+        addNsecRecordsForUniqueNames(additionalAnswerRecords,
+                answerInfo.iterator(), additionalAnswerInfo.iterator());
+
         if (answerInfo.size() == 0 && additionalAnswerRecords.size() == 0) {
             return null;
         }
@@ -581,15 +609,15 @@
             @Nullable List<RecordInfo<MdnsPointerRecord>> servicePtrRecords,
             @Nullable RecordInfo<MdnsServiceRecord> serviceSrvRecord,
             @Nullable RecordInfo<MdnsTextRecord> serviceTxtRecord,
-            boolean replyUnicast, long now, @NonNull List<RecordInfo<?>> answerInfo,
-            @NonNull List<MdnsRecord> additionalAnswerRecords,
+            boolean replyUnicast, long now, @NonNull Set<RecordInfo<?>> answerInfo,
+            @NonNull Set<RecordInfo<?>> additionalAnswerInfo,
             @NonNull List<MdnsRecord> knownAnswerRecords) {
         boolean hasDnsSdPtrRecordAnswer = false;
         boolean hasDnsSdSrvRecordAnswer = false;
         boolean hasFullyOwnedNameMatch = false;
         boolean hasKnownAnswer = false;
 
-        final int answersStartIndex = answerInfo.size();
+        final int answersStartSize = answerInfo.size();
         for (RecordInfo<?> info : serviceRecords) {
 
              /* RFC6762 6.: the record name must match the question name, the record rrtype
@@ -645,7 +673,7 @@
         // ownership, for a type for which that name has no records, the responder MUST [...]
         // respond asserting the nonexistence of that record"
         if (hasFullyOwnedNameMatch && !hasKnownAnswer) {
-            additionalAnswerRecords.add(new MdnsNsecRecord(
+            MdnsNsecRecord nsecRecord = new MdnsNsecRecord(
                     question.getName(),
                     0L /* receiptTimeMillis */,
                     true /* cacheFlush */,
@@ -653,13 +681,14 @@
                     // be the same as the TTL that the record would have had, had it existed."
                     NAME_RECORDS_TTL_MILLIS,
                     question.getName(),
-                    new int[] { question.getType() }));
+                    new int[] { question.getType() });
+            additionalAnswerInfo.add(
+                    new RecordInfo<>(null /* serviceInfo */, nsecRecord, false /* isSharedName */));
         }
 
         // No more records to add if no answer
-        if (answerInfo.size() == answersStartIndex) return false;
+        if (answerInfo.size() == answersStartSize) return false;
 
-        final List<RecordInfo<?>> additionalAnswerInfo = new ArrayList<>();
         // RFC6763 12.1: if including PTR record, include the SRV and TXT records it names
         if (hasDnsSdPtrRecordAnswer) {
             if (serviceTxtRecord != null) {
@@ -678,15 +707,6 @@
                 }
             }
         }
-
-        for (RecordInfo<?> info : additionalAnswerInfo) {
-            additionalAnswerRecords.add(info.record);
-        }
-
-        // RFC6762 6.1: negative responses
-        addNsecRecordsForUniqueNames(additionalAnswerRecords,
-                answerInfo.listIterator(answersStartIndex),
-                additionalAnswerInfo.listIterator());
         return true;
     }
 
@@ -703,7 +723,7 @@
      *                      answer and additionalAnswer sections)
      */
     @SafeVarargs
-    private static void addNsecRecordsForUniqueNames(
+    private void addNsecRecordsForUniqueNames(
             List<MdnsRecord> destinationList,
             Iterator<RecordInfo<?>>... answerRecords) {
         // Group unique records by name. Use a TreeMap with comparator as arrays don't implement
@@ -719,6 +739,12 @@
 
         for (String[] nsecName : namesInAddedOrder) {
             final List<MdnsRecord> entryRecords = nsecByName.get(nsecName);
+
+            // Add NSEC records only when the answers include all unique records of this name
+            if (entryRecords.size() != countUniqueRecords(nsecName)) {
+                continue;
+            }
+
             long minTtl = Long.MAX_VALUE;
             final Set<Integer> types = new ArraySet<>(entryRecords.size());
             for (MdnsRecord record : entryRecords) {
@@ -736,6 +762,27 @@
         }
     }
 
+    /** Returns the number of unique records on this device for a given {@code name}. */
+    private int countUniqueRecords(String[] name) {
+        int cnt = countUniqueRecords(mGeneralRecords, name);
+
+        for (int i = 0; i < mServices.size(); i++) {
+            final ServiceRegistration registration = mServices.valueAt(i);
+            cnt += countUniqueRecords(registration.allRecords, name);
+        }
+        return cnt;
+    }
+
+    private static int countUniqueRecords(List<RecordInfo<?>> records, String[] name) {
+        int cnt = 0;
+        for (RecordInfo<?> record : records) {
+            if (!record.isSharedName && Arrays.equals(name, record.record.getName())) {
+                cnt++;
+            }
+        }
+        return cnt;
+    }
+
     /**
      * Add non-shared records to a map listing them by record name, and to a list of names that
      * remembers the adding order.
@@ -750,10 +797,10 @@
     private static void addNonSharedRecordsToMap(
             Iterator<RecordInfo<?>> records,
             Map<String[], List<MdnsRecord>> dest,
-            List<String[]> namesInAddedOrder) {
+            @Nullable List<String[]> namesInAddedOrder) {
         while (records.hasNext()) {
             final RecordInfo<?> record = records.next();
-            if (record.isSharedName) continue;
+            if (record.isSharedName || record.record instanceof MdnsNsecRecord) continue;
             final List<MdnsRecord> recordsForName = dest.computeIfAbsent(record.record.name,
                     key -> {
                         namesInAddedOrder.add(key);
diff --git a/tests/unit/java/com/android/server/connectivity/mdns/MdnsRecordRepositoryTest.kt b/tests/unit/java/com/android/server/connectivity/mdns/MdnsRecordRepositoryTest.kt
index 196f73f..4b1f166 100644
--- a/tests/unit/java/com/android/server/connectivity/mdns/MdnsRecordRepositoryTest.kt
+++ b/tests/unit/java/com/android/server/connectivity/mdns/MdnsRecordRepositoryTest.kt
@@ -22,6 +22,12 @@
 import android.os.Build
 import android.os.HandlerThread
 import com.android.server.connectivity.mdns.MdnsAnnouncer.AnnouncementInfo
+import com.android.server.connectivity.mdns.MdnsRecord.TYPE_A
+import com.android.server.connectivity.mdns.MdnsRecord.TYPE_AAAA
+import com.android.server.connectivity.mdns.MdnsRecord.TYPE_ANY
+import com.android.server.connectivity.mdns.MdnsRecord.TYPE_PTR
+import com.android.server.connectivity.mdns.MdnsRecord.TYPE_SRV
+import com.android.server.connectivity.mdns.MdnsRecord.TYPE_TXT
 import com.android.server.connectivity.mdns.MdnsRecordRepository.Dependencies
 import com.android.server.connectivity.mdns.MdnsRecordRepository.getReverseDnsAddress
 import com.android.server.connectivity.mdns.MdnsServiceInfo.TextEntry
@@ -38,6 +44,7 @@
 import kotlin.test.assertNotNull
 import kotlin.test.assertNull
 import kotlin.test.assertTrue
+import kotlin.test.fail
 import org.junit.After
 import org.junit.Before
 import org.junit.Test
@@ -398,31 +405,31 @@
                         true /* cacheFlush */,
                         120000L /* ttlMillis */,
                         v4AddrRev,
-                        intArrayOf(MdnsRecord.TYPE_PTR)),
+                        intArrayOf(TYPE_PTR)),
                 MdnsNsecRecord(TEST_HOSTNAME,
                         0L /* receiptTimeMillis */,
                         true /* cacheFlush */,
                         120000L /* ttlMillis */,
                         TEST_HOSTNAME,
-                        intArrayOf(MdnsRecord.TYPE_A, MdnsRecord.TYPE_AAAA)),
+                        intArrayOf(TYPE_A, TYPE_AAAA)),
                 MdnsNsecRecord(v6Addr1Rev,
                         0L /* receiptTimeMillis */,
                         true /* cacheFlush */,
                         120000L /* ttlMillis */,
                         v6Addr1Rev,
-                        intArrayOf(MdnsRecord.TYPE_PTR)),
+                        intArrayOf(TYPE_PTR)),
                 MdnsNsecRecord(v6Addr2Rev,
                         0L /* receiptTimeMillis */,
                         true /* cacheFlush */,
                         120000L /* ttlMillis */,
                         v6Addr2Rev,
-                        intArrayOf(MdnsRecord.TYPE_PTR)),
+                        intArrayOf(TYPE_PTR)),
                 MdnsNsecRecord(serviceName,
                         0L /* receiptTimeMillis */,
                         true /* cacheFlush */,
                         4500000L /* ttlMillis */,
                         serviceName,
-                        intArrayOf(MdnsRecord.TYPE_TXT, MdnsRecord.TYPE_SRV))
+                        intArrayOf(TYPE_TXT, TYPE_SRV))
         ), packet.additionalRecords)
     }
 
@@ -504,94 +511,276 @@
         assertEquals(7, replyCaseInsensitive.additionalAnswers.size)
     }
 
-    @Test
-    fun testGetReply() {
-        doGetReplyTest(queryWithSubtype = false)
-    }
-
-    @Test
-    fun testGetReply_WithSubtype() {
-        doGetReplyTest(queryWithSubtype = true)
-    }
-
-    private fun doGetReplyTest(queryWithSubtype: Boolean) {
-        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
-        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1,
-                setOf(TEST_SUBTYPE, TEST_SUBTYPE2))
-        val queriedName = if (!queryWithSubtype) arrayOf("_testservice", "_tcp", "local")
-                else arrayOf(TEST_SUBTYPE, "_sub", "_testservice", "_tcp", "local")
-
-        val questions = listOf(MdnsPointerRecord(queriedName, false /* isUnicast */))
-        val query = MdnsPacket(0 /* flags */, questions, listOf() /* answers */,
+    /**
+     * Creates mDNS query packet with given query names and types.
+     */
+    private fun makeQuery(vararg queries: Pair<Int, Array<String>>): MdnsPacket {
+        val questions = queries.map { (type, name) -> makeQuestionRecord(name, type) }
+        return MdnsPacket(0 /* flags */, questions, listOf() /* answers */,
                 listOf() /* authorityRecords */, listOf() /* additionalRecords */)
+    }
+
+    private fun makeQuestionRecord(name: Array<String>, type: Int): MdnsRecord {
+        when (type) {
+            TYPE_PTR -> return MdnsPointerRecord(name, false /* isUnicast */)
+            TYPE_SRV -> return MdnsServiceRecord(name, false /* isUnicast */)
+            TYPE_TXT -> return MdnsTextRecord(name, false /* isUnicast */)
+            TYPE_A, TYPE_AAAA -> return MdnsInetAddressRecord(name, type, false /* isUnicast */)
+            else -> fail("Unexpected question type: $type")
+        }
+    }
+
+    @Test
+    fun testGetReply_singlePtrQuestion_returnsSrvTxtAddressNsecRecords() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
         val src = InetSocketAddress(parseNumericAddress("192.0.2.123"), 5353)
+        val serviceName = arrayOf("MyTestService", "_testservice", "_tcp", "local")
+
+        val query = makeQuery(TYPE_PTR to arrayOf("_testservice", "_tcp", "local"))
         val reply = repository.getReply(query, src)
 
         assertNotNull(reply)
-        // Source address is IPv4
-        assertEquals(MdnsConstants.getMdnsIPv4Address(), reply.destination.address)
-        assertEquals(MdnsConstants.MDNS_PORT, reply.destination.port)
-
-        val serviceName = arrayOf("MyTestService", "_testservice", "_tcp", "local")
-
         assertEquals(listOf(
                 MdnsPointerRecord(
-                        queriedName,
-                        0L /* receiptTimeMillis */,
-                        false /* cacheFlush */,
-                        LONG_TTL,
-                        serviceName),
-        ), reply.answers)
-
+                    arrayOf("_testservice", "_tcp", "local"), 0L, false, LONG_TTL, serviceName)),
+            reply.answers)
         assertEquals(listOf(
-            MdnsTextRecord(
-                    serviceName,
-                    0L /* receiptTimeMillis */,
-                    true /* cacheFlush */,
-                    LONG_TTL,
-                    listOf() /* entries */),
-            MdnsServiceRecord(
-                    serviceName,
-                    0L /* receiptTimeMillis */,
-                    true /* cacheFlush */,
-                    SHORT_TTL,
-                    0 /* servicePriority */,
-                    0 /* serviceWeight */,
-                    TEST_PORT,
-                    TEST_HOSTNAME),
-            MdnsInetAddressRecord(
-                    TEST_HOSTNAME,
-                    0L /* receiptTimeMillis */,
-                    true /* cacheFlush */,
-                    SHORT_TTL,
-                    TEST_ADDRESSES[0].address),
-            MdnsInetAddressRecord(
-                    TEST_HOSTNAME,
-                    0L /* receiptTimeMillis */,
-                    true /* cacheFlush */,
-                    SHORT_TTL,
-                    TEST_ADDRESSES[1].address),
-            MdnsInetAddressRecord(
-                    TEST_HOSTNAME,
-                    0L /* receiptTimeMillis */,
-                    true /* cacheFlush */,
-                    SHORT_TTL,
-                    TEST_ADDRESSES[2].address),
-            MdnsNsecRecord(
-                    serviceName,
-                    0L /* receiptTimeMillis */,
-                    true /* cacheFlush */,
-                    LONG_TTL,
-                    serviceName /* nextDomain */,
-                    intArrayOf(MdnsRecord.TYPE_TXT, MdnsRecord.TYPE_SRV)),
-            MdnsNsecRecord(
-                    TEST_HOSTNAME,
-                    0L /* receiptTimeMillis */,
-                    true /* cacheFlush */,
-                    SHORT_TTL,
-                    TEST_HOSTNAME /* nextDomain */,
-                    intArrayOf(MdnsRecord.TYPE_A, MdnsRecord.TYPE_AAAA)),
-        ), reply.additionalAnswers)
+                MdnsTextRecord(serviceName, 0L, true, LONG_TTL, listOf()),
+                MdnsServiceRecord(serviceName, 0L, true, SHORT_TTL, 0, 0, TEST_PORT, TEST_HOSTNAME),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[0].address),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[1].address),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[2].address),
+                MdnsNsecRecord(serviceName, 0L, true, LONG_TTL, serviceName /* nextDomain */,
+                        intArrayOf(TYPE_TXT, TYPE_SRV)),
+                MdnsNsecRecord(TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_HOSTNAME /* nextDomain */,
+                        intArrayOf(TYPE_A, TYPE_AAAA)),
+            ), reply.additionalAnswers)
+    }
+
+    @Test
+    fun testGetReply_singleSubtypePtrQuestion_returnsSrvTxtAddressNsecRecords() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
+        val src = InetSocketAddress(parseNumericAddress("192.0.2.123"), 5353)
+        val serviceName = arrayOf("MyTestService", "_testservice", "_tcp", "local")
+
+        val query = makeQuery(
+                TYPE_PTR to arrayOf(TEST_SUBTYPE, "_sub", "_testservice", "_tcp", "local"))
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(
+                MdnsPointerRecord(
+                    arrayOf(TEST_SUBTYPE, "_sub", "_testservice", "_tcp", "local"), 0L, false,
+                    LONG_TTL, serviceName)),
+            reply.answers)
+        assertEquals(listOf(
+                MdnsTextRecord(serviceName, 0L, true, LONG_TTL, listOf()),
+                MdnsServiceRecord(serviceName, 0L, true, SHORT_TTL, 0, 0, TEST_PORT, TEST_HOSTNAME),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[0].address),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[1].address),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[2].address),
+                MdnsNsecRecord(serviceName, 0L, true, LONG_TTL, serviceName /* nextDomain */,
+                        intArrayOf(TYPE_TXT, TYPE_SRV)),
+                MdnsNsecRecord(TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_HOSTNAME /* nextDomain */,
+                        intArrayOf(TYPE_A, TYPE_AAAA)),
+            ), reply.additionalAnswers)
+    }
+
+    @Test
+    fun testGetReply_duplicatePtrQuestions_doesNotReturnDuplicateRecords() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
+        val src = InetSocketAddress(parseNumericAddress("192.0.2.123"), 5353)
+        val serviceName = arrayOf("MyTestService", "_testservice", "_tcp", "local")
+
+        val query = makeQuery(
+                TYPE_PTR to arrayOf("_testservice", "_tcp", "local"),
+                TYPE_PTR to arrayOf("_testservice", "_tcp", "local"))
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(
+                MdnsPointerRecord(
+                    arrayOf("_testservice", "_tcp", "local"), 0L, false, LONG_TTL, serviceName)),
+            reply.answers)
+        assertEquals(listOf(
+                MdnsTextRecord(serviceName, 0L, true, LONG_TTL, listOf()),
+                MdnsServiceRecord(serviceName, 0L, true, SHORT_TTL, 0, 0, TEST_PORT, TEST_HOSTNAME),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[0].address),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[1].address),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[2].address),
+                MdnsNsecRecord(serviceName, 0L, true, LONG_TTL, serviceName /* nextDomain */,
+                        intArrayOf(TYPE_TXT, TYPE_SRV)),
+                MdnsNsecRecord(TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_HOSTNAME /* nextDomain */,
+                        intArrayOf(TYPE_A, TYPE_AAAA)),
+            ), reply.additionalAnswers)
+    }
+
+    @Test
+    fun testGetReply_multiplePtrQuestionsWithSubtype_doesNotReturnDuplicateRecords() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
+        val src = InetSocketAddress(parseNumericAddress("192.0.2.123"), 5353)
+        val serviceName = arrayOf("MyTestService", "_testservice", "_tcp", "local")
+
+        val query = makeQuery(
+                TYPE_PTR to arrayOf("_testservice", "_tcp", "local"),
+                TYPE_PTR to arrayOf(TEST_SUBTYPE, "_sub", "_testservice", "_tcp", "local"))
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(
+                MdnsPointerRecord(
+                    arrayOf("_testservice", "_tcp", "local"), 0L, false, LONG_TTL, serviceName),
+                MdnsPointerRecord(
+                    arrayOf(TEST_SUBTYPE, "_sub", "_testservice", "_tcp", "local"),
+                    0L, false, LONG_TTL, serviceName)),
+            reply.answers)
+        assertEquals(listOf(
+                MdnsTextRecord(serviceName, 0L, true, LONG_TTL, listOf()),
+                MdnsServiceRecord(serviceName, 0L, true, SHORT_TTL, 0, 0, TEST_PORT, TEST_HOSTNAME),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[0].address),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[1].address),
+                MdnsInetAddressRecord(
+                    TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[2].address),
+                MdnsNsecRecord(serviceName, 0L, true, LONG_TTL, serviceName /* nextDomain */,
+                        intArrayOf(TYPE_TXT, TYPE_SRV)),
+                MdnsNsecRecord(TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_HOSTNAME /* nextDomain */,
+                        intArrayOf(TYPE_A, TYPE_AAAA)),
+            ), reply.additionalAnswers)
+    }
+
+    @Test
+    fun testGetReply_txtQuestion_returnsNoNsecRecord() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
+        val src = InetSocketAddress(parseNumericAddress("192.0.2.123"), 5353)
+        val serviceName = arrayOf("MyTestService", "_testservice", "_tcp", "local")
+
+        val query = makeQuery(TYPE_TXT to serviceName)
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(MdnsTextRecord(serviceName, 0L, true, LONG_TTL, listOf())),
+                reply.answers)
+        // No NSEC records because the reply doesn't include the SRV record
+        assertTrue(reply.additionalAnswers.isEmpty())
+    }
+
+    @Test
+    fun testGetReply_AAAAQuestionButNoIpv6Address_returnsNsecRecord() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(
+                TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE),
+                listOf(LinkAddress(parseNumericAddress("192.0.2.111"), 24)))
+        val src = InetSocketAddress(parseNumericAddress("192.0.2.123"), 5353)
+
+        val query = makeQuery(TYPE_AAAA to TEST_HOSTNAME)
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertTrue(reply.answers.isEmpty())
+        assertEquals(listOf(
+                MdnsNsecRecord(TEST_HOSTNAME, 0L, true, LONG_TTL, TEST_HOSTNAME /* nextDomain */,
+                        intArrayOf(TYPE_AAAA))),
+            reply.additionalAnswers)
+    }
+
+    @Test
+    fun testGetReply_ptrAndSrvQuestions_doesNotReturnSrvRecordInAdditionalAnswerSection() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
+        val src = InetSocketAddress(parseNumericAddress("192.0.2.123"), 5353)
+        val serviceName = arrayOf("MyTestService", "_testservice", "_tcp", "local")
+
+        val query = makeQuery(
+                TYPE_PTR to arrayOf("_testservice", "_tcp", "local"),
+                TYPE_SRV to serviceName)
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(
+                MdnsPointerRecord(
+                    arrayOf("_testservice", "_tcp", "local"), 0L, false, LONG_TTL, serviceName),
+                MdnsServiceRecord(
+                    serviceName, 0L, true, SHORT_TTL, 0, 0, TEST_PORT, TEST_HOSTNAME)),
+            reply.answers)
+        assertFalse(reply.additionalAnswers.any { it -> it is MdnsServiceRecord })
+    }
+
+    @Test
+    fun testGetReply_srvTxtAddressQuestions_returnsAllRecordsInAnswerSectionExceptNsec() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
+        val src = InetSocketAddress(parseNumericAddress("192.0.2.123"), 5353)
+        val serviceName = arrayOf("MyTestService", "_testservice", "_tcp", "local")
+
+        val query = makeQuery(
+                TYPE_SRV to serviceName,
+                TYPE_TXT to serviceName,
+                TYPE_SRV to serviceName,
+                TYPE_A to TEST_HOSTNAME,
+                TYPE_AAAA to TEST_HOSTNAME)
+        val reply = repository.getReply(query, src)
+
+        assertNotNull(reply)
+        assertEquals(listOf(
+                MdnsServiceRecord(serviceName, 0L, true, SHORT_TTL, 0, 0, TEST_PORT, TEST_HOSTNAME),
+                MdnsTextRecord(serviceName, 0L, true, LONG_TTL, listOf()),
+                MdnsInetAddressRecord(
+                        TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[0].address),
+                MdnsInetAddressRecord(
+                        TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[1].address),
+                MdnsInetAddressRecord(
+                        TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_ADDRESSES[2].address)),
+            reply.answers)
+        assertEquals(listOf(
+                MdnsNsecRecord(serviceName, 0L, true, LONG_TTL, serviceName /* nextDomain */,
+                        intArrayOf(TYPE_TXT, TYPE_SRV)),
+                MdnsNsecRecord(TEST_HOSTNAME, 0L, true, SHORT_TTL, TEST_HOSTNAME /* nextDomain */,
+                        intArrayOf(TYPE_A, TYPE_AAAA))),
+            reply.additionalAnswers)
+    }
+
+    @Test
+    fun testGetReply_queryWithIpv4Address_replyWithIpv4Address() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
+        val query = makeQuery(TYPE_PTR to arrayOf("_testservice", "_tcp", "local"))
+
+        val srcIpv4 = InetSocketAddress(parseNumericAddress("192.0.2.123"), 5353)
+        val replyIpv4 = repository.getReply(query, srcIpv4)
+
+        assertNotNull(replyIpv4)
+        assertEquals(MdnsConstants.getMdnsIPv4Address(), replyIpv4.destination.address)
+        assertEquals(MdnsConstants.MDNS_PORT, replyIpv4.destination.port)
+    }
+
+    @Test
+    fun testGetReply_queryWithIpv6Address_replyWithIpv6Address() {
+        val repository = MdnsRecordRepository(thread.looper, deps, TEST_HOSTNAME, flags)
+        repository.initWithService(TEST_SERVICE_ID_1, TEST_SERVICE_1, setOf(TEST_SUBTYPE))
+        val query = makeQuery(TYPE_PTR to arrayOf("_testservice", "_tcp", "local"))
+
+        val srcIpv6 = InetSocketAddress(parseNumericAddress("2001:db8::123"), 5353)
+        val replyIpv6 = repository.getReply(query, srcIpv6)
+
+        assertNotNull(replyIpv6)
+        assertEquals(MdnsConstants.getMdnsIPv6Address(), replyIpv6.destination.address)
+        assertEquals(MdnsConstants.MDNS_PORT, replyIpv6.destination.port)
     }
 
     @Test
@@ -1015,13 +1204,6 @@
                         SHORT_TTL,
                         TEST_ADDRESSES[2].address),
                 MdnsNsecRecord(
-                        serviceName,
-                        0L /* receiptTimeMillis */,
-                        true /* cacheFlush */,
-                        LONG_TTL,
-                        serviceName /* nextDomain */,
-                        intArrayOf(MdnsRecord.TYPE_SRV)),
-                MdnsNsecRecord(
                         TEST_HOSTNAME,
                         0L /* receiptTimeMillis */,
                         true /* cacheFlush */,
@@ -1064,8 +1246,9 @@
     serviceId: Int,
     serviceInfo: NsdServiceInfo,
     subtypes: Set<String> = setOf(),
+    addresses: List<LinkAddress> = TEST_ADDRESSES
 ): AnnouncementInfo {
-    updateAddresses(TEST_ADDRESSES)
+    updateAddresses(addresses)
     serviceInfo.setSubtypes(subtypes)
     addService(serviceId, serviceInfo)
     val probingInfo = setServiceProbing(serviceId)