Merge "[nearby]Remove out of date APIs for Fast Pair." into main
diff --git a/service-t/src/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiser.java b/service-t/src/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiser.java
index 0b2003f..58defa9 100644
--- a/service-t/src/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiser.java
+++ b/service-t/src/com/android/server/connectivity/mdns/MdnsInterfaceAdvertiser.java
@@ -416,13 +416,6 @@
         // recvbuf and src are reused after this returns; ensure references to src are not kept.
         final InetSocketAddress srcCopy = new InetSocketAddress(src.getAddress(), src.getPort());
 
-        if (DBG) {
-            mSharedLog.v("Parsed packet with " + packet.questions.size() + " questions, "
-                    + packet.answers.size() + " answers, "
-                    + packet.authorityRecords.size() + " authority, "
-                    + packet.additionalRecords.size() + " additional from " + srcCopy);
-        }
-
         Map<Integer, Integer> conflictingServices =
                 mRecordRepository.getConflictingServices(packet);
 
@@ -440,7 +433,14 @@
         // answer. One exception is simultaneous probe tiebreaking (rfc6762 8.2), in which case the
         // conflicting service is still probing and won't reply either.
         final MdnsReplyInfo answers = mRecordRepository.getReply(packet, srcCopy);
-
+        // Dump the query packet.
+        if (DBG || answers != null) {
+            mSharedLog.v("Parsed packet with transactionId(" + packet.transactionId + "): "
+                    + packet.questions.size() + " questions, "
+                    + packet.answers.size() + " answers, "
+                    + packet.authorityRecords.size() + " authority, "
+                    + packet.additionalRecords.size() + " additional from " + srcCopy);
+        }
         if (answers == null) return;
         mReplySender.queueReply(answers);
     }
diff --git a/service-t/src/com/android/server/connectivity/mdns/MdnsReplySender.java b/service-t/src/com/android/server/connectivity/mdns/MdnsReplySender.java
index a89b004..4708cb6 100644
--- a/service-t/src/com/android/server/connectivity/mdns/MdnsReplySender.java
+++ b/service-t/src/com/android/server/connectivity/mdns/MdnsReplySender.java
@@ -245,7 +245,7 @@
                 return;
             }
 
-            if (mEnableDebugLog) mSharedLog.v("Sending " + replyInfo);
+            mSharedLog.log("Sending " + replyInfo);
 
             final int flags = 0x8400; // Response, authoritative (rfc6762 18.4)
             final MdnsPacket packet = new MdnsPacket(flags,
diff --git a/staticlibs/testutils/app/connectivitychecker/src/com/android/testutils/connectivitypreparer/CarrierConfigSetupTest.kt b/staticlibs/testutils/app/connectivitychecker/src/com/android/testutils/connectivitypreparer/CarrierConfigSetupTest.kt
new file mode 100644
index 0000000..46e511e
--- /dev/null
+++ b/staticlibs/testutils/app/connectivitychecker/src/com/android/testutils/connectivitypreparer/CarrierConfigSetupTest.kt
@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2024 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.testutils.connectivitypreparer
+
+import android.Manifest.permission.MODIFY_PHONE_STATE
+import android.Manifest.permission.READ_PHONE_STATE
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.content.IntentFilter
+import android.content.pm.PackageManager.FEATURE_TELEPHONY_IMS
+import android.content.pm.PackageManager.FEATURE_WIFI
+import android.os.Build
+import android.os.Build.VERSION_CODES.UPSIDE_DOWN_CAKE
+import android.os.ParcelFileDescriptor
+import android.os.PersistableBundle
+import android.telephony.CarrierConfigManager
+import android.telephony.CarrierConfigManager.ACTION_CARRIER_CONFIG_CHANGED
+import android.telephony.SubscriptionManager
+import android.util.Log
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
+import com.android.net.module.util.ArrayTrackRecord
+import com.android.testutils.runAsShell
+import kotlin.test.assertNotNull
+import org.junit.Test
+import org.junit.runner.RunWith
+
+private const val CONFIG_CHANGE_TIMEOUT_MS = 10_000L
+private val TAG = CarrierConfigSetupTest::class.simpleName
+
+@RunWith(AndroidJUnit4::class)
+class CarrierConfigSetupTest {
+    private val context by lazy { InstrumentationRegistry.getInstrumentation().context }
+    private val pm by lazy { context.packageManager }
+    private val carrierConfigManager by lazy {
+        context.getSystemService(CarrierConfigManager::class.java)
+    }
+
+    @Test
+    fun testSetCarrierConfig() {
+        if (!shouldDisableIwlan()) return
+        overrideAllSubscriptions(PersistableBundle().apply {
+            putBoolean(CarrierConfigManager.KEY_CARRIER_WFC_IMS_AVAILABLE_BOOL, false)
+        })
+    }
+
+    @Test
+    fun testClearCarrierConfig() {
+        // set/clear are in different test runs so it is difficult to share state between them.
+        // The conditions to disable IWLAN should not change over time (in particular
+        // force_iwlan_mms is a readonly flag), so just perform the same check again on teardown.
+        // CarrierConfigManager overrides are cleared on reboot by default anyway, so any missed
+        // cleanup should not be too damaging.
+        if (!shouldDisableIwlan()) return
+        overrideAllSubscriptions(null)
+    }
+
+    private class ConfigChangedReceiver : BroadcastReceiver() {
+        val receivedSubIds = ArrayTrackRecord<Int>()
+        override fun onReceive(context: Context, intent: Intent) {
+            if (intent.action != ACTION_CARRIER_CONFIG_CHANGED) return
+            val subIdx = intent.getIntExtra(SubscriptionManager.EXTRA_SUBSCRIPTION_INDEX, -1)
+            // It is possible this is a configuration change for a different setting, so the test
+            // may not wait for long enough. Unfortunately calling CarrierConfigManager to check
+            // if the config was applied does not help because it will always return the override,
+            // even if it was not applied to the subscription yet.
+            // In practice, it is very unlikely that a different broadcast arrives, and then a test
+            // flakes because of the iwlan behavior in the time it takes for the config to be
+            // applied.
+            Log.d(TAG, "Received config change for sub $subIdx")
+            receivedSubIds.add(subIdx)
+        }
+    }
+
+    private fun overrideAllSubscriptions(bundle: PersistableBundle?) {
+        runAsShell(READ_PHONE_STATE, MODIFY_PHONE_STATE) {
+            val receiver = ConfigChangedReceiver()
+            context.registerReceiver(receiver, IntentFilter(ACTION_CARRIER_CONFIG_CHANGED))
+            val subscriptions = context.getSystemService(SubscriptionManager::class.java)
+                .activeSubscriptionInfoList
+            subscriptions?.forEach { subInfo ->
+                Log.d(TAG, "Overriding config for subscription $subInfo")
+                carrierConfigManager.overrideConfig(subInfo.subscriptionId, bundle)
+            }
+            // Don't wait after each update before the next one, but expect all updates to be done
+            // eventually
+            subscriptions?.forEach { subInfo ->
+                assertNotNull(receiver.receivedSubIds.poll(CONFIG_CHANGE_TIMEOUT_MS, pos = 0) {
+                    it == subInfo.subscriptionId
+                }, "Config override broadcast not received for subscription $subInfo")
+            }
+        }
+    }
+
+    private fun shouldDisableIwlan(): Boolean {
+        // IWLAN on U 24Q2 release (U QPR3) causes cell data to reconnect when Wi-Fi is toggled due
+        // to the implementation of the force_iwlan_mms feature, which does not work well with
+        // multinetworking tests. Disable the feature on such builds (b/368477391).
+        // The behavior changed in more recent releases (V) so only U 24Q2 is affected.
+        return pm.hasSystemFeature(FEATURE_TELEPHONY_IMS) && pm.hasSystemFeature(FEATURE_WIFI) &&
+                Build.VERSION.SDK_INT == UPSIDE_DOWN_CAKE &&
+                isForceIwlanMmsEnabled()
+    }
+
+    private fun isForceIwlanMmsEnabled(): Boolean {
+        val uiAutomation = InstrumentationRegistry.getInstrumentation().uiAutomation
+        val flagEnabledRegex = Regex(
+            """telephony/com\.android\.internal\.telephony\.flags\.force_iwlan_mms:""" +
+                    """.*ENABLED \(system\)""")
+        ParcelFileDescriptor.AutoCloseInputStream(
+            uiAutomation.executeShellCommand("printflags")).bufferedReader().use { reader ->
+                return reader.lines().anyMatch {
+                    it.contains(flagEnabledRegex)
+                }
+        }
+    }
+}
\ No newline at end of file
diff --git a/staticlibs/testutils/host/java/com/android/testutils/ConnectivityTestTargetPreparer.kt b/staticlibs/testutils/host/java/com/android/testutils/ConnectivityTestTargetPreparer.kt
index 435fdd8..f6168af 100644
--- a/staticlibs/testutils/host/java/com/android/testutils/ConnectivityTestTargetPreparer.kt
+++ b/staticlibs/testutils/host/java/com/android/testutils/ConnectivityTestTargetPreparer.kt
@@ -28,6 +28,7 @@
 private const val CONNECTIVITY_CHECKER_APK = "ConnectivityTestPreparer.apk"
 private const val CONNECTIVITY_PKG_NAME = "com.android.testutils.connectivitypreparer"
 private const val CONNECTIVITY_CHECK_CLASS = "$CONNECTIVITY_PKG_NAME.ConnectivityCheckTest"
+private const val CARRIER_CONFIG_SETUP_CLASS = "$CONNECTIVITY_PKG_NAME.CarrierConfigSetupTest"
 
 // As per the <instrumentation> defined in the checker manifest
 private const val CONNECTIVITY_CHECK_RUNNER_NAME = "androidx.test.runner.AndroidJUnitRunner"
@@ -84,27 +85,28 @@
         installer.setShouldGrantPermission(true)
         installer.setUp(testInfo)
 
-        val testMethods = mutableListOf<String>()
+        val testMethods = mutableListOf<Pair<String, String>>()
         if (!ignoreWifiCheck) {
-            testMethods.add("testCheckWifiSetup")
+            testMethods.add(CONNECTIVITY_CHECK_CLASS to "testCheckWifiSetup")
         }
         if (!ignoreMobileDataCheck) {
-            testMethods.add("testCheckTelephonySetup")
+            testMethods.add(CARRIER_CONFIG_SETUP_CLASS to "testSetCarrierConfig")
+            testMethods.add(CONNECTIVITY_CHECK_CLASS to "testCheckTelephonySetup")
         }
 
         testMethods.forEach {
-            runTestMethod(testInfo, it)
+            runTestMethod(testInfo, it.first, it.second)
         }
     }
 
-    private fun runTestMethod(testInfo: TestInformation, method: String) {
+    private fun runTestMethod(testInfo: TestInformation, clazz: String, method: String) {
         val runner = DefaultRemoteAndroidTestRunner(
             CONNECTIVITY_PKG_NAME,
             CONNECTIVITY_CHECK_RUNNER_NAME,
             testInfo.device.iDevice
         )
         runner.runOptions = "--no-hidden-api-checks"
-        runner.setMethodName(CONNECTIVITY_CHECK_CLASS, method)
+        runner.setMethodName(clazz, method)
 
         val receiver = CollectingTestListener()
         if (!testInfo.device.runInstrumentationTests(runner, receiver)) {
@@ -187,6 +189,9 @@
 
     override fun tearDown(testInfo: TestInformation, e: Throwable?) {
         if (isTearDownDisabled) return
+        if (!ignoreMobileDataCheck) {
+            runTestMethod(testInfo, CARRIER_CONFIG_SETUP_CLASS, "testClearCarrierConfig")
+        }
         installer.tearDown(testInfo, e)
         setUpdaterNetworkingEnabled(
             testInfo,
diff --git a/tests/cts/net/src/android/net/cts/NsdManagerTest.kt b/tests/cts/net/src/android/net/cts/NsdManagerTest.kt
index ad6fe63..7fc8863 100644
--- a/tests/cts/net/src/android/net/cts/NsdManagerTest.kt
+++ b/tests/cts/net/src/android/net/cts/NsdManagerTest.kt
@@ -326,6 +326,15 @@
         it.port = TEST_PORT
     }
 
+    private fun makePacketReader(network: TestTapNetwork = testNetwork1) = PollPacketReader(
+            Handler(handlerThread.looper),
+            network.iface.fileDescriptor.fileDescriptor,
+            1500 /* maxPacketSize */
+    ).also {
+        it.startAsyncForTest()
+        handlerThread.waitForIdle(TIMEOUT_MS)
+    }
+
     @After
     fun tearDown() {
         runAsShell(MANAGE_TEST_NETWORKS) {
@@ -1298,14 +1307,7 @@
         assumeTrue(TestUtils.shouldTestTApis())
 
         val si = makeTestServiceInfo(testNetwork1.network)
-
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
+        val packetReader = makePacketReader()
 
         // Register service on testNetwork1
         val registrationRecord = NsdRegistrationRecord()
@@ -1345,13 +1347,7 @@
                     parseNumericAddress("2001:db8::3"))
         }
 
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
+        val packetReader = makePacketReader()
 
         // Register service on testNetwork1
         val registrationRecord = NsdRegistrationRecord()
@@ -1391,13 +1387,7 @@
             hostname = customHostname
         }
 
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
+        val packetReader = makePacketReader()
 
         // Register service on testNetwork1
         val registrationRecord = NsdRegistrationRecord()
@@ -1438,13 +1428,7 @@
         val registrationRecord = NsdRegistrationRecord()
         val discoveryRecord = NsdDiscoveryRecord()
         val registeredService = registerService(registrationRecord, si)
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
+        val packetReader = makePacketReader()
 
         tryTest {
             assertNotNull(packetReader.pollForAdvertisement(serviceName, serviceType),
@@ -1518,13 +1502,7 @@
         val registrationRecord = NsdRegistrationRecord()
         val discoveryRecord = NsdDiscoveryRecord()
         val registeredService = registerService(registrationRecord, si)
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
+        val packetReader = makePacketReader()
 
         tryTest {
             assertNotNull(packetReader.pollForAdvertisement(serviceName, serviceType),
@@ -1587,13 +1565,7 @@
         val registrationRecord = NsdRegistrationRecord()
         val discoveryRecord = NsdDiscoveryRecord()
         val registeredService = registerService(registrationRecord, si)
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
+        val packetReader = makePacketReader()
 
         tryTest {
             assertNotNull(packetReader.pollForAdvertisement(serviceName, serviceType),
@@ -1630,13 +1602,7 @@
     fun testDiscoveryWithPtrOnlyResponse_ServiceIsFound() {
         // Register service on testNetwork1
         val discoveryRecord = NsdDiscoveryRecord()
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
+        val packetReader = makePacketReader()
 
         nsdManager.discoverServices(
             serviceType,
@@ -1675,9 +1641,12 @@
                 assertEmpty(it.hostAddresses)
                 assertEquals(0, it.attributes.size)
             }
-        } cleanup {
+        } cleanupStep {
             nsdManager.stopServiceDiscovery(discoveryRecord)
             discoveryRecord.expectCallback<DiscoveryStopped>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
     }
 
@@ -1688,79 +1657,77 @@
     fun testResolveWhenServerSendsNoAdditionalRecord() {
         // Resolve service on testNetwork1
         val resolveRecord = NsdResolveRecord()
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
-
+        val packetReader = makePacketReader()
         val si = makeTestServiceInfo(testNetwork1.network)
         nsdManager.resolveService(si, { it.run() }, resolveRecord)
 
-        val serviceFullName = "$serviceName.$serviceType.local"
-        // The query should ask for ANY, since both SRV and TXT are requested. Note legacy
-        // mdnsresponder will ask for SRV and TXT separately, and will not proceed to asking for
-        // address records without an answer for both.
-        val srvTxtQuery = packetReader.pollForQuery(serviceFullName, DnsResolver.TYPE_ANY)
-        assertNotNull(srvTxtQuery)
+        tryTest {
+            val serviceFullName = "$serviceName.$serviceType.local"
+            // The query should ask for ANY, since both SRV and TXT are requested. Note legacy
+            // mdnsresponder will ask for SRV and TXT separately, and will not proceed to asking for
+            // address records without an answer for both.
+            val srvTxtQuery = packetReader.pollForQuery(serviceFullName, DnsResolver.TYPE_ANY)
+            assertNotNull(srvTxtQuery)
 
-        /*
-        Generated with:
-        scapy.raw(scapy.dns_compress(scapy.DNS(rd=0, qr=1, aa=1, qd = None, an =
-            scapy.DNSRRSRV(rrname='NsdTest123456789._nmt123456789._tcp.local',
-                rclass=0x8001, port=31234, target='testhost.local', ttl=120) /
-            scapy.DNSRR(rrname='NsdTest123456789._nmt123456789._tcp.local', type='TXT', ttl=120,
-                rdata='testkey=testvalue')
-        ))).hex()
-         */
-        val srvTxtResponsePayload = HexDump.hexStringToByteArray(
-            "000084000000000200000000104" +
-                "e7364546573743132333435363738390d5f6e6d74313233343536373839045f746370056c6f6" +
-                "3616c0000218001000000780011000000007a020874657374686f7374c030c00c00100001000" +
-                "00078001211746573746b65793d7465737476616c7565"
-        )
-        replaceServiceNameAndTypeWithTestSuffix(srvTxtResponsePayload)
-        packetReader.sendResponse(buildMdnsPacket(srvTxtResponsePayload))
+            /*
+            Generated with:
+            scapy.raw(scapy.dns_compress(scapy.DNS(rd=0, qr=1, aa=1, qd = None, an =
+                scapy.DNSRRSRV(rrname='NsdTest123456789._nmt123456789._tcp.local',
+                    rclass=0x8001, port=31234, target='testhost.local', ttl=120) /
+                scapy.DNSRR(rrname='NsdTest123456789._nmt123456789._tcp.local', type='TXT', ttl=120,
+                    rdata='testkey=testvalue')
+            ))).hex()
+             */
+            val srvTxtResponsePayload = HexDump.hexStringToByteArray(
+                    "000084000000000200000000104" +
+                            "e7364546573743132333435363738390d5f6e6d74313233343536373839045f7463" +
+                            "70056c6f63616c0000218001000000780011000000007a020874657374686f7374c" +
+                            "030c00c0010000100000078001211746573746b65793d7465737476616c7565"
+            )
+            replaceServiceNameAndTypeWithTestSuffix(srvTxtResponsePayload)
+            packetReader.sendResponse(buildMdnsPacket(srvTxtResponsePayload))
 
-        val testHostname = "testhost.local"
-        val addressQuery = packetReader.pollForQuery(
-            testHostname,
-            DnsResolver.TYPE_A,
-            DnsResolver.TYPE_AAAA
-        )
-        assertNotNull(addressQuery)
+            val testHostname = "testhost.local"
+            val addressQuery = packetReader.pollForQuery(
+                    testHostname,
+                    DnsResolver.TYPE_A,
+                    DnsResolver.TYPE_AAAA
+            )
+            assertNotNull(addressQuery)
 
-        /*
-        Generated with:
-        scapy.raw(scapy.dns_compress(scapy.DNS(rd=0, qr=1, aa=1, qd = None, an =
-            scapy.DNSRR(rrname='testhost.local', type='A', ttl=120,
-                rdata='192.0.2.123') /
-            scapy.DNSRR(rrname='testhost.local', type='AAAA', ttl=120,
-                rdata='2001:db8::123')
-        ))).hex()
-         */
-        val addressPayload = HexDump.hexStringToByteArray(
-            "0000840000000002000000000874657374" +
-                "686f7374056c6f63616c0000010001000000780004c000027bc00c001c000100000078001020" +
-                "010db8000000000000000000000123"
-        )
-        packetReader.sendResponse(buildMdnsPacket(addressPayload))
+            /*
+            Generated with:
+            scapy.raw(scapy.dns_compress(scapy.DNS(rd=0, qr=1, aa=1, qd = None, an =
+                scapy.DNSRR(rrname='testhost.local', type='A', ttl=120,
+                    rdata='192.0.2.123') /
+                scapy.DNSRR(rrname='testhost.local', type='AAAA', ttl=120,
+                    rdata='2001:db8::123')
+            ))).hex()
+             */
+            val addressPayload = HexDump.hexStringToByteArray(
+                    "0000840000000002000000000874657374" +
+                            "686f7374056c6f63616c0000010001000000780004c000027bc00c001c000100000" +
+                            "078001020010db8000000000000000000000123"
+            )
+            packetReader.sendResponse(buildMdnsPacket(addressPayload))
 
-        val serviceResolved = resolveRecord.expectCallback<ServiceResolved>()
-        serviceResolved.serviceInfo.let {
-            assertEquals(serviceName, it.serviceName)
-            assertEquals(".$serviceType", it.serviceType)
-            assertEquals(testNetwork1.network, it.network)
-            assertEquals(31234, it.port)
-            assertEquals(1, it.attributes.size)
-            assertArrayEquals("testvalue".encodeToByteArray(), it.attributes["testkey"])
+            val serviceResolved = resolveRecord.expectCallback<ServiceResolved>()
+            serviceResolved.serviceInfo.let {
+                assertEquals(serviceName, it.serviceName)
+                assertEquals(".$serviceType", it.serviceType)
+                assertEquals(testNetwork1.network, it.network)
+                assertEquals(31234, it.port)
+                assertEquals(1, it.attributes.size)
+                assertArrayEquals("testvalue".encodeToByteArray(), it.attributes["testkey"])
+            }
+            assertEquals(
+                    setOf(parseNumericAddress("192.0.2.123"), parseNumericAddress("2001:db8::123")),
+                    serviceResolved.serviceInfo.hostAddresses.toSet()
+            )
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
-        assertEquals(
-                setOf(parseNumericAddress("192.0.2.123"), parseNumericAddress("2001:db8::123")),
-                serviceResolved.serviceInfo.hostAddresses.toSet()
-        )
     }
 
     @Test
@@ -1774,13 +1741,9 @@
         // Register service on testNetwork1
         val registrationRecord = NsdRegistrationRecord()
         var nsResponder: NSResponder? = null
+        val packetReader = makePacketReader()
         tryTest {
             registerService(registrationRecord, si)
-            val packetReader = PollPacketReader(Handler(handlerThread.looper),
-                    testNetwork1.iface.fileDescriptor.fileDescriptor, 1500 /* maxPacketSize */)
-            packetReader.startAsyncForTest()
-
-            handlerThread.waitForIdle(TIMEOUT_MS)
             /*
             Send a "query unicast" query.
             Generated with:
@@ -1805,10 +1768,13 @@
                         pkt.dstAddr == testSrcAddr
             }
             assertNotNull(reply)
-        } cleanup {
+        } cleanupStep {
             nsResponder?.stop()
             nsdManager.unregisterService(registrationRecord)
             registrationRecord.expectCallback<ServiceUnregistered>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
     }
 
@@ -1824,13 +1790,9 @@
         // Register service on testNetwork1
         val registrationRecord = NsdRegistrationRecord()
         var nsResponder: NSResponder? = null
+        val packetReader = makePacketReader()
         tryTest {
             registerService(registrationRecord, si)
-            val packetReader = PollPacketReader(Handler(handlerThread.looper),
-                    testNetwork1.iface.fileDescriptor.fileDescriptor, 1500 /* maxPacketSize */)
-            packetReader.startAsyncForTest()
-
-            handlerThread.waitForIdle(TIMEOUT_MS)
             /*
             Send a query with a known answer. Expect to receive a response containing TXT record
             only.
@@ -1895,10 +1857,13 @@
                         pkt.dstAddr == testSrcAddr
             }
             assertNotNull(reply2)
-        } cleanup {
+        } cleanupStep {
             nsResponder?.stop()
             nsdManager.unregisterService(registrationRecord)
             registrationRecord.expectCallback<ServiceUnregistered>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
     }
 
@@ -1914,13 +1879,9 @@
         // Register service on testNetwork1
         val registrationRecord = NsdRegistrationRecord()
         var nsResponder: NSResponder? = null
+        val packetReader = makePacketReader()
         tryTest {
             registerService(registrationRecord, si)
-            val packetReader = PollPacketReader(Handler(handlerThread.looper),
-                    testNetwork1.iface.fileDescriptor.fileDescriptor, 1500 /* maxPacketSize */)
-            packetReader.startAsyncForTest()
-
-            handlerThread.waitForIdle(TIMEOUT_MS)
             /*
             Send a query with truncated bit set.
             Generated with:
@@ -1976,10 +1937,13 @@
                         pkt.dstAddr == testSrcAddr
             }
             assertNotNull(reply)
-        } cleanup {
+        } cleanupStep {
             nsResponder?.stop()
             nsdManager.unregisterService(registrationRecord)
             registrationRecord.expectCallback<ServiceUnregistered>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
     }
 
@@ -1991,13 +1955,7 @@
 
         // Register service on testNetwork1
         val discoveryRecord = NsdDiscoveryRecord()
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
+        val packetReader = makePacketReader()
 
         nsdManager.discoverServices(
             serviceType,
@@ -2043,9 +2001,12 @@
                         pkt.isReplyFor("$serviceType.local", DnsResolver.TYPE_PTR)
             }
             assertNotNull(query)
-        } cleanup {
+        } cleanupStep {
             nsdManager.stopServiceDiscovery(discoveryRecord)
             discoveryRecord.expectCallback<DiscoveryStopped>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
     }
 
@@ -2355,14 +2316,7 @@
             it.port = TEST_PORT
             it.publicKey = publicKey
         }
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
-
+        val packetReader = makePacketReader()
         val registrationRecord = NsdRegistrationRecord()
         val discoveryRecord = NsdDiscoveryRecord()
         tryTest {
@@ -2394,8 +2348,11 @@
             nsdManager.stopServiceDiscovery(discoveryRecord)
 
             discoveryRecord.expectCallback<DiscoveryStopped>()
-        } cleanup {
+        } cleanupStep {
             nsdManager.unregisterService(registrationRecord)
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
     }
 
@@ -2410,14 +2367,7 @@
                     parseNumericAddress("2001:db8::2"))
             it.publicKey = publicKey
         }
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
-
+        val packetReader = makePacketReader()
         val registrationRecord = NsdRegistrationRecord()
         tryTest {
             registerService(registrationRecord, si)
@@ -2439,8 +2389,11 @@
                         it.nsType == DnsResolver.TYPE_A
             }
             assertEquals(3, addressRecords.size)
-        } cleanup {
+        } cleanupStep {
             nsdManager.unregisterService(registrationRecord)
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
     }
 
@@ -2467,14 +2420,7 @@
             it.hostAddresses = listOf()
             it.publicKey = publicKey
         }
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
-
+        val packetReader = makePacketReader()
         val registrationRecord1 = NsdRegistrationRecord()
         val registrationRecord2 = NsdRegistrationRecord()
         tryTest {
@@ -2508,9 +2454,12 @@
             assertTrue(keyRecords.any { it.dName == "$customHostname.local" })
             assertTrue(keyRecords.all { it.ttl == NAME_RECORDS_TTL_MILLIS })
             assertTrue(keyRecords.all { it.rr.contentEquals(publicKey) })
-        } cleanup {
+        } cleanupStep {
             nsdManager.unregisterService(registrationRecord1)
             nsdManager.unregisterService(registrationRecord2)
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
     }
 
@@ -2582,13 +2531,7 @@
             "test_nsd_avoid_advertising_empty_txt_records",
             "1"
         )
-        val packetReader = PollPacketReader(
-                Handler(handlerThread.looper),
-                testNetwork1.iface.fileDescriptor.fileDescriptor,
-                1500 /* maxPacketSize */
-        )
-        packetReader.startAsyncForTest()
-        handlerThread.waitForIdle(TIMEOUT_MS)
+        val packetReader = makePacketReader()
 
         // Test behavior described in RFC6763 6.1: empty TXT records are not allowed, but TXT
         // records with a zero length string are equivalent.
@@ -2607,12 +2550,85 @@
             assertEquals(1, txtRecords.size)
             // The TXT record should contain as single zero
             assertContentEquals(byteArrayOf(0), txtRecords[0].rr)
-        } cleanup {
+        } cleanupStep {
             nsdManager.unregisterService(registrationRecord)
             registrationRecord.expectCallback<ServiceUnregistered>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
         }
     }
 
+    private fun verifyCachedServicesRemoval(isCachedServiceRemoved: Boolean) {
+        val si = makeTestServiceInfo(testNetwork1.network)
+        // Register service on testNetwork1
+        val registrationRecord = NsdRegistrationRecord()
+        registerService(registrationRecord, si)
+        // Register a discovery request.
+        val discoveryRecord = NsdDiscoveryRecord()
+        val packetReader = makePacketReader()
+
+        tryTest {
+            nsdManager.discoverServices(
+                    serviceType,
+                    NsdManager.PROTOCOL_DNS_SD,
+                    testNetwork1.network,
+                    { it.run() },
+                    discoveryRecord
+            )
+
+            discoveryRecord.expectCallback<DiscoveryStarted>()
+            val foundInfo = discoveryRecord.waitForServiceDiscovered(
+                    serviceName, serviceType, testNetwork1.network)
+            assertEquals(testNetwork1.network, foundInfo.network)
+            // Verify that the service is not in the cache (a query is sent).
+            assertNotNull(packetReader.pollForQuery(
+                    "$serviceType.local", DnsResolver.TYPE_PTR, timeoutMs = 0L))
+
+            // Stop discovery to trigger the cached services removal process.
+            nsdManager.stopServiceDiscovery(discoveryRecord)
+            discoveryRecord.expectCallback<DiscoveryStopped>()
+
+            val serviceFullName = "$serviceName.$serviceType.local"
+            if (isCachedServiceRemoved) {
+                Thread.sleep(100L)
+                resolveService(foundInfo)
+                // Verify the resolution query will send because cached services are remove after
+                // exceeding the retention time.
+                assertNotNull(packetReader.pollForQuery(
+                        serviceFullName, DnsResolver.TYPE_ANY, timeoutMs = 0L))
+            } else {
+                resolveService(foundInfo)
+                // Verify the resolution query will not be sent because services are still cached.
+                assertNull(packetReader.pollForQuery(
+                        serviceFullName, DnsResolver.TYPE_ANY, timeoutMs = 0L))
+            }
+        } cleanupStep {
+            nsdManager.unregisterService(registrationRecord)
+            registrationRecord.expectCallback<ServiceUnregistered>()
+        } cleanup {
+            packetReader.handler.post { packetReader.stop() }
+            handlerThread.waitForIdle(TIMEOUT_MS)
+        }
+    }
+
+    @Test
+    fun testRemoveCachedServices() {
+        deviceConfigRule.setConfig(NAMESPACE_TETHERING, "test_nsd_cached_services_removal", "1")
+        verifyCachedServicesRemoval(isCachedServiceRemoved = false)
+    }
+
+    @Test
+    fun testRemoveCachedServices_ShortRetentionTime() {
+        deviceConfigRule.setConfig(NAMESPACE_TETHERING, "test_nsd_cached_services_removal", "1")
+        deviceConfigRule.setConfig(
+                NAMESPACE_TETHERING,
+                "test_nsd_cached_services_retention_time",
+                "1"
+        )
+        verifyCachedServicesRemoval(isCachedServiceRemoved = true)
+    }
+
     private fun hasServiceTypeClientsForNetwork(clients: List<String>, network: Network): Boolean {
         return clients.any { client -> client.substring(
                 client.indexOf("network=") + "network=".length,
diff --git a/thread/tests/integration/src/android/net/thread/InternetAccessTest.kt b/thread/tests/integration/src/android/net/thread/InternetAccessTest.kt
new file mode 100644
index 0000000..9b787f5
--- /dev/null
+++ b/thread/tests/integration/src/android/net/thread/InternetAccessTest.kt
@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2024 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.thread
+
+import android.content.Context
+import android.net.DnsResolver.CLASS_IN
+import android.net.DnsResolver.TYPE_A
+import android.net.DnsResolver.TYPE_AAAA
+import android.net.InetAddresses.parseNumericAddress
+import android.net.thread.utils.FullThreadDevice
+import android.net.thread.utils.InfraNetworkDevice
+import android.net.thread.utils.IntegrationTestUtils.DEFAULT_DATASET
+import android.net.thread.utils.IntegrationTestUtils.joinNetworkAndWaitForOmr
+import android.net.thread.utils.IntegrationTestUtils.newPacketReader
+import android.net.thread.utils.IntegrationTestUtils.setUpInfraNetwork
+import android.net.thread.utils.IntegrationTestUtils.startInfraDeviceAndWaitForOnLinkAddr
+import android.net.thread.utils.IntegrationTestUtils.tearDownInfraNetwork
+import android.net.thread.utils.IntegrationTestUtils.waitFor
+import android.net.thread.utils.OtDaemonController
+import android.net.thread.utils.TestDnsServer
+import android.net.thread.utils.ThreadFeatureCheckerRule
+import android.net.thread.utils.ThreadFeatureCheckerRule.RequiresSimulationThreadDevice
+import android.net.thread.utils.ThreadFeatureCheckerRule.RequiresThreadFeature
+import android.net.thread.utils.ThreadNetworkControllerWrapper
+import android.os.Handler
+import android.os.HandlerThread
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.filters.LargeTest
+import com.android.net.module.util.DnsPacket
+import com.android.net.module.util.DnsPacket.ANSECTION
+import com.android.testutils.PollPacketReader
+import com.android.testutils.TestNetworkTracker
+import com.google.common.truth.Truth.assertThat
+import java.net.Inet4Address
+import java.net.InetAddress
+import java.time.Duration
+import org.junit.After
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+/** Integration test cases for Thread Internet Access features. */
+@RunWith(AndroidJUnit4::class)
+@RequiresThreadFeature
+@RequiresSimulationThreadDevice
+@LargeTest
+class InternetAccessTest {
+    private val TAG = BorderRoutingTest::class.java.simpleName
+    private val NUM_FTD = 1
+    private val DNS_SERVER_ADDR = parseNumericAddress("8.8.8.8") as Inet4Address
+    private val ANSWER_RECORDS =
+        listOf(
+            DnsPacket.DnsRecord.makeAOrAAAARecord(
+                ANSECTION,
+                "google.com",
+                CLASS_IN,
+                30 /* ttl */,
+                parseNumericAddress("1.2.3.4"),
+            ),
+            DnsPacket.DnsRecord.makeAOrAAAARecord(
+                ANSECTION,
+                "google.com",
+                CLASS_IN,
+                30 /* ttl */,
+                parseNumericAddress("2001::234"),
+            ),
+        )
+
+    @get:Rule val threadRule = ThreadFeatureCheckerRule()
+
+    private val context: Context = ApplicationProvider.getApplicationContext()
+    private val controller = requireNotNull(ThreadNetworkControllerWrapper.newInstance(context))
+    private lateinit var otCtl: OtDaemonController
+    private lateinit var handlerThread: HandlerThread
+    private lateinit var handler: Handler
+    private lateinit var infraNetworkTracker: TestNetworkTracker
+    private lateinit var ftds: ArrayList<FullThreadDevice>
+    private lateinit var infraNetworkReader: PollPacketReader
+    private lateinit var infraDevice: InfraNetworkDevice
+    private lateinit var dnsServer: TestDnsServer
+
+    @Before
+    @Throws(Exception::class)
+    fun setUp() {
+        // TODO: b/323301831 - This is a workaround to avoid unnecessary delay to re-form a network
+        otCtl = OtDaemonController()
+        otCtl.factoryReset()
+
+        handlerThread = HandlerThread(javaClass.simpleName)
+        handlerThread.start()
+        handler = Handler(handlerThread.looper)
+        ftds = ArrayList()
+
+        infraNetworkTracker = setUpInfraNetwork(context, controller)
+        controller.setEnabledAndWait(true)
+        controller.joinAndWait(DEFAULT_DATASET)
+
+        // Creates a infra network device.
+        infraNetworkReader = newPacketReader(infraNetworkTracker.testIface, handler)
+        infraDevice = startInfraDeviceAndWaitForOnLinkAddr(infraNetworkReader)
+
+        // Create a DNS server
+        dnsServer = TestDnsServer(infraNetworkReader, DNS_SERVER_ADDR, ANSWER_RECORDS)
+
+        // Create Ftds
+        for (i in 0 until NUM_FTD) {
+            ftds.add(FullThreadDevice(15 + i /* node ID */))
+        }
+    }
+
+    @After
+    @Throws(Exception::class)
+    fun tearDown() {
+        controller.setTestNetworkAsUpstreamAndWait(null)
+        controller.leaveAndWait()
+        tearDownInfraNetwork(infraNetworkTracker)
+
+        dnsServer.stop()
+
+        handlerThread.quitSafely()
+        handlerThread.join()
+
+        ftds.forEach { it.destroy() }
+        ftds.clear()
+    }
+
+    @Test
+    fun nat64Enabled_threadDeviceResolvesHost_hostIsResolved() {
+        controller.setNat64EnabledAndWait(true)
+        waitFor({ otCtl.hasNat64PrefixInNetdata() }, Duration.ofSeconds(10))
+        val ftd = ftds[0]
+        joinNetworkAndWaitForOmr(ftd, DEFAULT_DATASET)
+        dnsServer.start()
+
+        val ipv4Addresses =
+            ftd.resolveHost("google.com", TYPE_A).map { extractIpv4AddressFromMappedAddress(it) }
+        assertThat(ipv4Addresses).isEqualTo(listOf(parseNumericAddress("1.2.3.4")))
+        val ipv6Addresses = ftd.resolveHost("google.com", TYPE_AAAA)
+        assertThat(ipv6Addresses).isEqualTo(listOf(parseNumericAddress("2001::234")))
+    }
+
+    @Test
+    fun nat64Disabled_threadDeviceResolvesHost_hostIsNotResolved() {
+        controller.setNat64EnabledAndWait(false)
+        val ftd = ftds[0]
+        joinNetworkAndWaitForOmr(ftd, DEFAULT_DATASET)
+        dnsServer.start()
+
+        assertThat(ftd.resolveHost("google.com", TYPE_A)).isEmpty()
+        assertThat(ftd.resolveHost("google.com", TYPE_AAAA)).isEmpty()
+    }
+
+    private fun extractIpv4AddressFromMappedAddress(address: InetAddress): Inet4Address {
+        return InetAddress.getByAddress(address.address.slice(12 until 16).toByteArray())
+            as Inet4Address
+    }
+}
diff --git a/thread/tests/integration/src/android/net/thread/utils/FullThreadDevice.java b/thread/tests/integration/src/android/net/thread/utils/FullThreadDevice.java
index 083a841..5b532c7 100644
--- a/thread/tests/integration/src/android/net/thread/utils/FullThreadDevice.java
+++ b/thread/tests/integration/src/android/net/thread/utils/FullThreadDevice.java
@@ -15,6 +15,8 @@
  */
 package android.net.thread.utils;
 
+import static android.net.DnsResolver.TYPE_A;
+import static android.net.DnsResolver.TYPE_AAAA;
 import static android.net.thread.utils.IntegrationTestUtils.SERVICE_DISCOVERY_TIMEOUT;
 import static android.net.thread.utils.IntegrationTestUtils.waitFor;
 
@@ -354,6 +356,31 @@
         executeCommand("dns config " + address);
     }
 
+    /** Resolves the {@code queryType} record of the {@code hostname} via DNS. */
+    public List<InetAddress> resolveHost(String hostname, int queryType) {
+        // CLI output:
+        // DNS response for hostname.com. - fd12::abc1 TTL:50 fd12::abc2 TTL:50 fd12::abc3 TTL:50
+
+        String command;
+        switch (queryType) {
+            case TYPE_A -> command = "resolve4";
+            case TYPE_AAAA -> command = "resolve";
+            default -> throw new IllegalArgumentException("Invalid query type: " + queryType);
+        }
+        final List<InetAddress> addresses = new ArrayList<>();
+        String line;
+        try {
+            line = executeCommand("dns " + command + " " + hostname).get(0);
+        } catch (IllegalStateException e) {
+            return addresses;
+        }
+        final String[] addressTtlPairs = line.split("-")[1].strip().split(" ");
+        for (int i = 0; i < addressTtlPairs.length; i += 2) {
+            addresses.add(InetAddresses.parseNumericAddress(addressTtlPairs[i]));
+        }
+        return addresses;
+    }
+
     /** Returns the first browsed service instance of {@code serviceType}. */
     public NsdServiceInfo browseService(String serviceType) {
         // CLI output:
diff --git a/thread/tests/integration/src/android/net/thread/utils/TestDnsServer.kt b/thread/tests/integration/src/android/net/thread/utils/TestDnsServer.kt
new file mode 100644
index 0000000..c52fc49
--- /dev/null
+++ b/thread/tests/integration/src/android/net/thread/utils/TestDnsServer.kt
@@ -0,0 +1,170 @@
+/*
+ * Copyright (C) 2024 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.thread.utils
+
+import android.net.thread.utils.IntegrationTestUtils.pollForPacket
+import android.system.OsConstants.IPPROTO_IP
+import android.system.OsConstants.IPPROTO_UDP
+import com.android.net.module.util.DnsPacket
+import com.android.net.module.util.PacketBuilder
+import com.android.net.module.util.Struct
+import com.android.net.module.util.structs.Ipv4Header
+import com.android.net.module.util.structs.UdpHeader
+import com.android.testutils.PollPacketReader
+import java.net.InetAddress
+import java.nio.ByteBuffer
+import kotlin.concurrent.thread
+
+/**
+ * A class that simulates a DNS server.
+ *
+ * <p>The server responds to DNS requests with the given {@code answerRecords}.
+ *
+ * @param packetReader the packet reader to poll DNS requests from
+ * @param serverAddress the address of the DNS server
+ * @param answerRecords the records to respond to the DNS requests
+ */
+class TestDnsServer(
+    private val packetReader: PollPacketReader,
+    private val serverAddress: InetAddress,
+    private val answerRecords: List<DnsPacket.DnsRecord>,
+) {
+    private val TAG = TestDnsServer::class.java.simpleName
+    private val DNS_UDP_PORT = 53
+    private var workerThread: Thread? = null
+
+    private class TestDnsPacket : DnsPacket {
+
+        constructor(buf: ByteArray) : super(buf)
+
+        constructor(
+            header: DnsHeader,
+            qd: List<DnsRecord>,
+            an: List<DnsRecord>,
+        ) : super(header, qd, an) {}
+
+        val header = super.mHeader
+        val records = super.mRecords
+    }
+
+    /**
+     * Starts the DNS server to respond to DNS requests.
+     *
+     * <p> The server polls the DNS requests from the {@code packetReader} and responds with the
+     * {@code answerRecords}. The server will automatically stop when it fails to poll a DNS request
+     * within the timeout (3000 ms, as defined in IntegrationTestUtils).
+     */
+    fun start() {
+        workerThread = thread {
+            var requestPacket: ByteArray
+            while (true) {
+                requestPacket = pollForDnsPacket() ?: break
+                val buf = ByteBuffer.wrap(requestPacket)
+                packetReader.sendResponse(buildDnsResponse(buf, answerRecords))
+            }
+        }
+    }
+
+    /** Stops the DNS server. */
+    fun stop() {
+        workerThread?.join()
+    }
+
+    private fun pollForDnsPacket(): ByteArray? {
+        val filter =
+            fun(packet: ByteArray): Boolean {
+                val buf = ByteBuffer.wrap(packet)
+                val ipv4Header = Struct.parse(Ipv4Header::class.java, buf) ?: return false
+                val udpHeader = Struct.parse(UdpHeader::class.java, buf) ?: return false
+                return ipv4Header.dstIp == serverAddress && udpHeader.dstPort == DNS_UDP_PORT
+            }
+        return pollForPacket(packetReader, filter)
+    }
+
+    private fun buildDnsResponse(
+        requestPacket: ByteBuffer,
+        serverAnswers: List<DnsPacket.DnsRecord>,
+    ): ByteBuffer? {
+        val requestIpv4Header = Struct.parse(Ipv4Header::class.java, requestPacket) ?: return null
+        val requestUdpHeader = Struct.parse(UdpHeader::class.java, requestPacket) ?: return null
+        val remainingRequestPacket = ByteArray(requestPacket.remaining())
+        requestPacket.get(remainingRequestPacket)
+        val requestDnsPacket = TestDnsPacket(remainingRequestPacket)
+        val requestDnsHeader = requestDnsPacket.header
+
+        val answerRecords =
+            buildDnsAnswerRecords(requestDnsPacket.records[DnsPacket.QDSECTION], serverAnswers)
+        // TODO: return NXDOMAIN if no answer is found.
+        val responseFlags = 1 shl 15 // QR bit
+        val responseDnsHeader =
+            DnsPacket.DnsHeader(
+                requestDnsHeader.id,
+                responseFlags,
+                requestDnsPacket.records[DnsPacket.QDSECTION].size,
+                answerRecords.size,
+            )
+        val responseDnsPacket =
+            TestDnsPacket(
+                responseDnsHeader,
+                requestDnsPacket.records[DnsPacket.QDSECTION],
+                answerRecords,
+            )
+
+        val buf =
+            PacketBuilder.allocate(
+                false /* hasEther */,
+                IPPROTO_IP,
+                IPPROTO_UDP,
+                responseDnsPacket.bytes.size,
+            )
+
+        val packetBuilder = PacketBuilder(buf)
+        packetBuilder.writeIpv4Header(
+            requestIpv4Header.tos,
+            requestIpv4Header.id,
+            requestIpv4Header.flagsAndFragmentOffset,
+            0x40 /* ttl */,
+            IPPROTO_UDP.toByte(),
+            requestIpv4Header.dstIp, /* srcIp */
+            requestIpv4Header.srcIp, /* dstIp */
+        )
+        packetBuilder.writeUdpHeader(
+            requestUdpHeader.dstPort.toShort() /* srcPort */,
+            requestUdpHeader.srcPort.toShort(), /* dstPort */
+        )
+        buf.put(responseDnsPacket.bytes)
+
+        return packetBuilder.finalizePacket()
+    }
+
+    private fun buildDnsAnswerRecords(
+        questions: List<DnsPacket.DnsRecord>,
+        serverAnswers: List<DnsPacket.DnsRecord>,
+    ): List<DnsPacket.DnsRecord> {
+        val answers = ArrayList<DnsPacket.DnsRecord>()
+        for (answer in serverAnswers) {
+            if (
+                questions.any {
+                    answer.dName.equals(it.dName, ignoreCase = true) && answer.nsType == it.nsType
+                }
+            ) {
+                answers.add(answer)
+            }
+        }
+        return answers
+    }
+}