Add MdnsAnnouncer
MdnsAnnouncer is a implementations of MdnsPacketRepeater, which sends a
packet at various intervals.
It will be used to send initial advertisements when a service is
registered or there is a network change.
Bug: 241738458
Test: atest
Change-Id: If187d023dd48d9b575431759cc6b67460bc0d33b
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsAnnouncer.java b/service/mdns/com/android/server/connectivity/mdns/MdnsAnnouncer.java
new file mode 100644
index 0000000..91e08a8
--- /dev/null
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsAnnouncer.java
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity.mdns;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.os.Looper;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.net.SocketAddress;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.Supplier;
+
+/**
+ * Sends mDns announcements when a service registration changes and at regular intervals.
+ *
+ * This allows maintaining other hosts' caches up-to-date. See RFC6762 8.3.
+ */
+public class MdnsAnnouncer extends MdnsPacketRepeater<MdnsAnnouncer.AnnouncementInfo> {
+ private static final long ANNOUNCEMENT_INITIAL_DELAY_MS = 1000L;
+ @VisibleForTesting
+ static final int ANNOUNCEMENT_COUNT = 8;
+
+ @NonNull
+ private final String mLogTag;
+
+ static class AnnouncementInfo implements MdnsPacketRepeater.Request {
+ @NonNull
+ private final MdnsPacket mPacket;
+ @NonNull
+ private final Supplier<Iterable<SocketAddress>> mDestinationsSupplier;
+
+ AnnouncementInfo(List<MdnsRecord> announcedRecords, List<MdnsRecord> additionalRecords,
+ Supplier<Iterable<SocketAddress>> destinationsSupplier) {
+ // Records to announce (as answers)
+ // Records to place in the "Additional records", with NSEC negative responses
+ // to mark records that have been verified unique
+ final int flags = 0x8400; // Response, authoritative (rfc6762 18.4)
+ mPacket = new MdnsPacket(flags,
+ Collections.emptyList() /* questions */,
+ announcedRecords,
+ Collections.emptyList() /* authorityRecords */,
+ additionalRecords);
+ mDestinationsSupplier = destinationsSupplier;
+ }
+
+ @Override
+ public MdnsPacket getPacket(int index) {
+ return mPacket;
+ }
+
+ @Override
+ public Iterable<SocketAddress> getDestinations(int index) {
+ return mDestinationsSupplier.get();
+ }
+
+ @Override
+ public long getDelayMs(int nextIndex) {
+ // Delay is doubled for each announcement
+ return ANNOUNCEMENT_INITIAL_DELAY_MS << (nextIndex - 1);
+ }
+
+ @Override
+ public int getNumSends() {
+ return ANNOUNCEMENT_COUNT;
+ }
+ }
+
+ public MdnsAnnouncer(@NonNull String interfaceTag, @NonNull Looper looper,
+ @NonNull MdnsReplySender replySender,
+ @Nullable PacketRepeaterCallback<AnnouncementInfo> cb) {
+ super(looper, replySender, cb);
+ mLogTag = MdnsAnnouncer.class.getSimpleName() + "/" + interfaceTag;
+ }
+
+ @Override
+ protected String getTag() {
+ return mLogTag;
+ }
+
+ // TODO: Notify MdnsRecordRepository that the records were announced for that service ID,
+ // so it can update the last advertised timestamp of the associated records.
+}
diff --git a/tests/unit/java/com/android/server/connectivity/mdns/MdnsAnnouncerTest.kt b/tests/unit/java/com/android/server/connectivity/mdns/MdnsAnnouncerTest.kt
new file mode 100644
index 0000000..e9325d5
--- /dev/null
+++ b/tests/unit/java/com/android/server/connectivity/mdns/MdnsAnnouncerTest.kt
@@ -0,0 +1,283 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity.mdns
+
+import android.net.InetAddresses.parseNumericAddress
+import android.os.Build
+import android.os.HandlerThread
+import android.os.SystemClock
+import com.android.internal.util.HexDump
+import com.android.server.connectivity.mdns.MdnsAnnouncer.AnnouncementInfo
+import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo
+import com.android.testutils.DevSdkIgnoreRunner
+import java.net.DatagramPacket
+import java.net.Inet6Address
+import java.net.InetAddress
+import java.net.InetSocketAddress
+import java.net.MulticastSocket
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.ArgumentCaptor
+import org.mockito.Mockito.any
+import org.mockito.Mockito.atLeast
+import org.mockito.Mockito.mock
+import org.mockito.Mockito.timeout
+import org.mockito.Mockito.verify
+
+private const val FIRST_ANNOUNCES_DELAY = 100L
+private const val FIRST_ANNOUNCES_COUNT = 2
+private const val NEXT_ANNOUNCES_DELAY = 1L
+private const val TEST_TIMEOUT_MS = 1000L
+
+private val destinationsSupplier = {
+ listOf(InetSocketAddress(MdnsConstants.getMdnsIPv6Address(), MdnsConstants.MDNS_PORT)) }
+
+@RunWith(DevSdkIgnoreRunner::class)
+@IgnoreUpTo(Build.VERSION_CODES.S_V2)
+class MdnsAnnouncerTest {
+
+ private val thread = HandlerThread(MdnsAnnouncerTest::class.simpleName)
+ private val socket = mock(MulticastSocket::class.java)
+ private val buffer = ByteArray(1500)
+
+ @Before
+ fun setUp() {
+ thread.start()
+ }
+
+ @After
+ fun tearDown() {
+ thread.quitSafely()
+ }
+
+ private class TestAnnouncementInfo(
+ announcedRecords: List<MdnsRecord>,
+ additionalRecords: List<MdnsRecord>
+ )
+ : AnnouncementInfo(announcedRecords, additionalRecords, destinationsSupplier) {
+ override fun getDelayMs(nextIndex: Int) =
+ if (nextIndex < FIRST_ANNOUNCES_COUNT) {
+ FIRST_ANNOUNCES_DELAY
+ } else {
+ NEXT_ANNOUNCES_DELAY
+ }
+ }
+
+ @Test
+ fun testAnnounce() {
+ val replySender = MdnsReplySender(thread.looper, socket, buffer)
+ @Suppress("UNCHECKED_CAST")
+ val cb = mock(MdnsPacketRepeater.PacketRepeaterCallback::class.java)
+ as MdnsPacketRepeater.PacketRepeaterCallback<AnnouncementInfo>
+ val announcer = MdnsAnnouncer("testiface", thread.looper, replySender, cb)
+ /*
+ The expected packet replicates records announced when registering a service, as observed in
+ the legacy mDNS implementation (some ordering differs to be more readable).
+ Obtained with scapy 2.5.0 RC3 (2.4.5 does not compress TLDs like .arpa properly) with:
+ scapy.raw(scapy.dns_compress(scapy.DNS(rd=0, qr=1, aa=1,
+ qd = None,
+ an =
+ scapy.DNSRR(type='PTR', rrname='123.0.2.192.in-addr.arpa.', rdata='Android.local',
+ rclass=0x8001, ttl=120) /
+ scapy.DNSRR(type='PTR',
+ rrname='3.2.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.B.D.0.1.0.0.2.ip6.arpa',
+ rdata='Android.local', rclass=0x8001, ttl=120) /
+ scapy.DNSRR(type='PTR',
+ rrname='6.5.4.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.B.D.0.1.0.0.2.ip6.arpa',
+ rdata='Android.local', rclass=0x8001, ttl=120) /
+ scapy.DNSRR(type='PTR', rrname='_testtype._tcp.local',
+ rdata='testservice._testtype._tcp.local', rclass='IN', ttl=4500) /
+ scapy.DNSRRSRV(rrname='testservice._testtype._tcp.local', rclass=0x8001, port=31234,
+ target='Android.local', ttl=120) /
+ scapy.DNSRR(type='TXT', rrname='testservice._testtype._tcp.local', rclass=0x8001, rdata='',
+ ttl=4500) /
+ scapy.DNSRR(type='A', rrname='Android.local', rclass=0x8001, rdata='192.0.2.123', ttl=120) /
+ scapy.DNSRR(type='AAAA', rrname='Android.local', rclass=0x8001, rdata='2001:db8::123',
+ ttl=120) /
+ scapy.DNSRR(type='AAAA', rrname='Android.local', rclass=0x8001, rdata='2001:db8::456',
+ ttl=120),
+ ar =
+ scapy.DNSRRNSEC(rrname='123.0.2.192.in-addr.arpa.', rclass=0x8001, ttl=120,
+ nextname='123.0.2.192.in-addr.arpa.', typebitmaps=[12]) /
+ scapy.DNSRRNSEC(
+ rrname='3.2.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.B.D.0.1.0.0.2.ip6.arpa',
+ rclass=0x8001, ttl=120,
+ nextname='3.2.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.B.D.0.1.0.0.2.ip6.arpa',
+ typebitmaps=[12]) /
+ scapy.DNSRRNSEC(
+ rrname='6.5.4.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.B.D.0.1.0.0.2.ip6.arpa',
+ rclass=0x8001, ttl=120,
+ nextname='6.5.4.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.B.D.0.1.0.0.2.ip6.arpa',
+ typebitmaps=[12]) /
+ scapy.DNSRRNSEC(
+ rrname='testservice._testtype._tcp.local', rclass=0x8001, ttl=4500,
+ nextname='testservice._testtype._tcp.local', typebitmaps=[16, 33]) /
+ scapy.DNSRRNSEC(
+ rrname='Android.local', rclass=0x8001, ttl=120, nextname='Android.local',
+ typebitmaps=[1, 28]))
+ )).hex().upper()
+ */
+ val expected = "00008400000000090000000503313233013001320331393207696E2D61646472046172706" +
+ "100000C800100000078000F07416E64726F6964056C6F63616C00013301320131013001300130013" +
+ "00130013001300130013001300130013001300130013001300130013001300130013001380142014" +
+ "40130013101300130013203697036C020000C8001000000780002C030013601350134C045000C800" +
+ "1000000780002C030095F7465737474797065045F746370C038000C000100001194000E0B7465737" +
+ "473657276696365C0A5C0C000218001000000780008000000007A02C030C0C000108001000011940" +
+ "000C03000018001000000780004C000027BC030001C800100000078001020010DB80000000000000" +
+ "00000000123C030001C800100000078001020010DB8000000000000000000000456C00C002F80010" +
+ "00000780006C00C00020008C03F002F8001000000780006C03F00020008C091002F8001000000780" +
+ "006C09100020008C0C0002F8001000011940009C0C000050000800040C030002F800100000078000" +
+ "8C030000440000008"
+
+ val hostname = arrayOf("Android", "local")
+ val serviceType = arrayOf("_testtype", "_tcp", "local")
+ val serviceName = arrayOf("testservice", "_testtype", "_tcp", "local")
+ val v4Addr = parseNumericAddress("192.0.2.123")
+ val v6Addr1 = parseNumericAddress("2001:DB8::123")
+ val v6Addr2 = parseNumericAddress("2001:DB8::456")
+ val v4AddrRev = arrayOf("123", "0", "2", "192", "in-addr", "arpa")
+ val v6Addr1Rev = getReverseV6AddressName(v6Addr1)
+ val v6Addr2Rev = getReverseV6AddressName(v6Addr2)
+
+ val announcedRecords = listOf(
+ // Reverse address records
+ MdnsPointerRecord(v4AddrRev,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ hostname),
+ MdnsPointerRecord(v6Addr1Rev,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ hostname),
+ MdnsPointerRecord(v6Addr2Rev,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ hostname),
+ // Service registration records (RFC6763)
+ MdnsPointerRecord(
+ serviceType,
+ 0L /* receiptTimeMillis */,
+ // Not a unique name owned by the announcer, so cacheFlush=false
+ false /* cacheFlush */,
+ 4500000L /* ttlMillis */,
+ serviceName),
+ MdnsServiceRecord(
+ serviceName,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ 0 /* servicePriority */,
+ 0 /* serviceWeight */,
+ 31234 /* servicePort */,
+ hostname),
+ MdnsTextRecord(
+ serviceName,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 4500000L /* ttlMillis */,
+ emptyList() /* entries */),
+ // Address records for the hostname
+ MdnsInetAddressRecord(hostname,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ v4Addr),
+ MdnsInetAddressRecord(hostname,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ v6Addr1),
+ MdnsInetAddressRecord(hostname,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ v6Addr2))
+ // Negative responses (RFC6762 6.1)
+ val additionalRecords = listOf(
+ MdnsNsecRecord(v4AddrRev,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ v4AddrRev,
+ intArrayOf(MdnsRecord.TYPE_PTR)),
+ MdnsNsecRecord(v6Addr1Rev,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ v6Addr1Rev,
+ intArrayOf(MdnsRecord.TYPE_PTR)),
+ MdnsNsecRecord(v6Addr2Rev,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ v6Addr2Rev,
+ intArrayOf(MdnsRecord.TYPE_PTR)),
+ MdnsNsecRecord(serviceName,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 4500000L /* ttlMillis */,
+ serviceName,
+ intArrayOf(MdnsRecord.TYPE_TXT, MdnsRecord.TYPE_SRV)),
+ MdnsNsecRecord(hostname,
+ 0L /* receiptTimeMillis */,
+ true /* cacheFlush */,
+ 120000L /* ttlMillis */,
+ hostname,
+ intArrayOf(MdnsRecord.TYPE_A, MdnsRecord.TYPE_AAAA)))
+ val request = TestAnnouncementInfo(announcedRecords, additionalRecords)
+
+ val timeStart = SystemClock.elapsedRealtime()
+ val startDelay = 50L
+ val sendId = 1
+ announcer.startSending(sendId, request, startDelay)
+
+ val captor = ArgumentCaptor.forClass(DatagramPacket::class.java)
+ repeat(FIRST_ANNOUNCES_COUNT) { i ->
+ verify(cb, timeout(TEST_TIMEOUT_MS)).onSent(i, request)
+ verify(socket, atLeast(i + 1)).send(any())
+ val now = SystemClock.elapsedRealtime()
+ assertTrue(now > timeStart + startDelay + i * FIRST_ANNOUNCES_DELAY)
+ assertTrue(now < timeStart + startDelay + (i + 1) * FIRST_ANNOUNCES_DELAY)
+ }
+
+ // Subsequent announces should happen quickly (NEXT_ANNOUNCES_DELAY)
+ verify(socket, timeout(TEST_TIMEOUT_MS).times(MdnsAnnouncer.ANNOUNCEMENT_COUNT))
+ .send(captor.capture())
+ verify(cb, timeout(TEST_TIMEOUT_MS)).onFinished(request)
+
+ captor.allValues.forEach {
+ assertEquals(expected, HexDump.toHexString(it.data))
+ }
+ }
+}
+
+/**
+ * Compute 2001:db8::1 --> 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.B.D.1.0.0.2.ip6.arpa
+ */
+private fun getReverseV6AddressName(addr: InetAddress): Array<String> {
+ assertTrue(addr is Inet6Address)
+ return addr.address.flatMapTo(mutableListOf("arpa", "ip6")) {
+ HexDump.toHexString(it).toCharArray().map(Char::toString)
+ }.reversed().toTypedArray()
+}