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[Feature sync] Fix issue where multiple SRV records with same host are not fully resolved

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For Matter, a device may have a single host with multiple A/AAAA
records, but multiple PTR/SRV pairs that represent different
operational identities for the same device.

Currently, MdnsResponseDecoder looks for only a single matching
MdnsResponse by hostname when looping through the A/AAAA records
(which will leave the second response incomplete). Updated with a
flag that will allow returning all MdnsResponses which match the
given hostname and update the Inet records for all responses.

Bug: 254155029
Test: atest FrameworksNetTests
      Verified with a Matter device with two identities that the
      second response is incomplete without this change.
      Additionally, added unit tests to verify the before and
      after behavior with a real packet capture from the device.
Change-Id: Ic4a101b305c039f6cd7fd557246a2bfdaf0c781a
This commit is contained in:
Paul Hu
2022-10-03 15:41:13 +08:00
parent 6540583f08
commit e62d151d1e
3 changed files with 153 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
service/mdns/com/android/server/connectivity/mdns/MdnsConfigs.java
View File

@@ -101,4 +101,8 @@ public class MdnsConfigs {
public static boolean allowNetworkInterfaceIndexPropagation() {
return true;
}
public static boolean allowMultipleSrvRecordsPerHost() {
return true;
}
}

55
service/mdns/com/android/server/connectivity/mdns/MdnsResponseDecoder.java
View File

@@ -25,6 +25,7 @@ import com.android.server.connectivity.mdns.util.MdnsLogger;
import java.io.EOFException;
import java.io.IOException;
import java.net.DatagramPacket;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
@@ -37,6 +38,8 @@ public class MdnsResponseDecoder {
public static final int SUCCESS = 0;
private static final String TAG = "MdnsResponseDecoder";
private static final MdnsLogger LOGGER = new MdnsLogger(TAG);
private final boolean allowMultipleSrvRecordsPerHost =
MdnsConfigs.allowMultipleSrvRecordsPerHost();
private final String[] serviceType;
private final Clock clock;
@@ -281,13 +284,18 @@ public class MdnsResponseDecoder {
for (MdnsRecord record : records) {
if (record instanceof MdnsInetAddressRecord) {
MdnsInetAddressRecord inetRecord = (MdnsInetAddressRecord) record;
MdnsResponse response = findResponseWithHostName(responses, inetRecord.getName());
if (inetRecord.getInet4Address() != null && response != null) {
response.setInet4AddressRecord(inetRecord);
response.setInterfaceIndex(interfaceIndex);
} else if (inetRecord.getInet6Address() != null && response != null) {
response.setInet6AddressRecord(inetRecord);
response.setInterfaceIndex(interfaceIndex);
if (allowMultipleSrvRecordsPerHost) {
List<MdnsResponse> matchingResponses =
findResponsesWithHostName(responses, inetRecord.getName());
for (MdnsResponse response : matchingResponses) {
assignInetRecord(response, inetRecord, interfaceIndex);
}
} else {
MdnsResponse response =
findResponseWithHostName(responses, inetRecord.getName());
if (response != null) {
assignInetRecord(response, inetRecord, interfaceIndex);
}
}
}
}
@@ -295,6 +303,39 @@ public class MdnsResponseDecoder {
return SUCCESS;
}
private static void assignInetRecord(
MdnsResponse response, MdnsInetAddressRecord inetRecord, int interfaceIndex) {
if (inetRecord.getInet4Address() != null) {
response.setInet4AddressRecord(inetRecord);
response.setInterfaceIndex(interfaceIndex);
} else if (inetRecord.getInet6Address() != null) {
response.setInet6AddressRecord(inetRecord);
response.setInterfaceIndex(interfaceIndex);
}
}
private static List<MdnsResponse> findResponsesWithHostName(
@Nullable List<MdnsResponse> responses, String[] hostName) {
if (responses == null || responses.isEmpty()) {
return List.of();
}
List<MdnsResponse> result = null;
for (MdnsResponse response : responses) {
MdnsServiceRecord serviceRecord = response.getServiceRecord();
if (serviceRecord == null) {
continue;
}
if (Arrays.equals(serviceRecord.getServiceHost(), hostName)) {
if (result == null) {
result = new ArrayList<>(/* initialCapacity= */ responses.size());
}
result.add(response);
}
}
return result == null ? List.of() : result;
}
public static class Clock {
public long elapsedRealtime() {
return SystemClock.elapsedRealtime();

101
tests/unit/java/com/android/server/connectivity/mdns/MdnsResponseDecoderTests.java
View File

@@ -26,11 +26,14 @@ import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import static org.mockito.Mockito.mock;
import android.net.InetAddresses;
import com.android.net.module.util.HexDump;
import com.android.testutils.DevSdkIgnoreRule;
import com.android.testutils.DevSdkIgnoreRunner;
import org.junit.Before;
import org.junit.Ignore;
import org.junit.Test;
import org.junit.runner.RunWith;
@@ -106,9 +109,49 @@ public class MdnsResponseDecoderTests {
+ "63616C0000018001000000780004C0A8010A000001800100000078"
+ "0004C0A8010A00000000000000");
// Expected to contain two SRV records which point to the same hostname.
private static final byte[] matterDuplicateHostname = HexDump.hexStringToByteArray(
"00008000000000080000000A095F7365727669636573075F646E732D73"
+ "64045F756470056C6F63616C00000C000100000078000F075F6D61"
+ "74746572045F746370C023C00C000C000100000078001A125F4943"
+ "324639453337374632454139463430045F737562C034C034000C00"
+ "0100000078002421433246394533373746324541394634302D3030"
+ "3030303030304534443041334641C034C04F000C00010000007800"
+ "02C075C00C000C0001000000780002C034C00C000C000100000078"
+ "0015125F4941413035363731333439334135343144C062C034000C"
+ "000100000078002421414130353637313334393341353431442D30"
+ "303030303030304331324446303344C034C0C1000C000100000078"
+ "0002C0E2C075002100010000007800150000000015A40C33433631"
+ "3035304338394638C023C07500100001000011940015084352493D"
+ "35303030074352413D33303003543D31C126001C00010000007800"
+ "10FE800000000000003E6105FFFE0C89F8C126001C000100000078"
+ "00102605A601A84657003E6105FFFE0C89F8C12600010001000000"
+ "780004C0A8018AC0E2002100010000007800080000000015A4C126"
+ "C0E200100001000011940015084352493D35303030074352413D33"
+ "303003543D31C126001C0001000000780010FE800000000000003E"
+ "6105FFFE0C89F8C126001C00010000007800102605A601A8465700"
+ "3E6105FFFE0C89F8C12600010001000000780004C0A8018A313035"
+ "304338394638C02300010001000000780004C0A8018AC0A0001000"
+ "0100001194003A0E56503D36353532312B3332373639084352493D"
+ "35303030074352413D33303003543D3106443D3236353704434D3D"
+ "320550483D33360350493D21433246394533373746324541394634"
+ "302D30303030303030304534443041334641C0F700210001000000"
+ "7800150000000015A40C334336313035304338394638C023214332"
+ "46394533373746324541394634302D303030303030303045344430"
+ "41334641C0F700100001000011940015084352493D353030300743"
+ "52413D33303003543D310C334336313035304338394638C023001C"
+ "0001000000780010FE800000000000003E6105FFFE0C89F80C3343"
+ "36313035304338394638C023001C00010000007800102605A601A8"
+ "4657003E6105FFFE0C89F80C334336313035304338394638C02300"
+ "010001000000780004C0A8018A0000000000000000000000000000"
+ "000000");
private static final String CAST_SERVICE_NAME = "_googlecast";
private static final String[] CAST_SERVICE_TYPE =
new String[] {CAST_SERVICE_NAME, "_tcp", "local"};
private static final String MATTER_SERVICE_NAME = "_matter";
private static final String[] MATTER_SERVICE_TYPE =
new String[] {MATTER_SERVICE_NAME, "_tcp", "local"};
private final List<MdnsResponse> responses = new LinkedList<>();
@@ -249,4 +292,62 @@ public class MdnsResponseDecoderTests {
assertEquals(responses.size(), 1);
assertEquals(responses.get(0).getInterfaceIndex(), 10);
}
@Test
public void decode_singleHostname_multipleSrvRecords_flagEnabled_multipleCompleteResponses() {
//MdnsScannerConfigsFlagsImpl.allowMultipleSrvRecordsPerHost.override(true);
MdnsResponseDecoder decoder = new MdnsResponseDecoder(mClock, MATTER_SERVICE_TYPE);
assertNotNull(matterDuplicateHostname);
DatagramPacket packet =
new DatagramPacket(matterDuplicateHostname, matterDuplicateHostname.length);
packet.setSocketAddress(
new InetSocketAddress(MdnsConstants.getMdnsIPv6Address(), MdnsConstants.MDNS_PORT));
responses.clear();
int errorCode = decoder.decode(packet, responses, /* interfaceIndex= */ 0);
assertEquals(MdnsResponseDecoder.SUCCESS, errorCode);
// This should emit two records:
assertEquals(2, responses.size());
MdnsResponse response1 = responses.get(0);
MdnsResponse response2 = responses.get(0);
// Both of which are complete:
assertTrue(response1.isComplete());
assertTrue(response2.isComplete());
// And should both have the same IPv6 address:
assertEquals(InetAddresses.parseNumericAddress("2605:a601:a846:5700:3e61:5ff:fe0c:89f8"),
response1.getInet6AddressRecord().getInet6Address());
assertEquals(InetAddresses.parseNumericAddress("2605:a601:a846:5700:3e61:5ff:fe0c:89f8"),
response2.getInet6AddressRecord().getInet6Address());
}
@Test
@Ignore("MdnsConfigs is not configurable currently.")
public void decode_singleHostname_multipleSrvRecords_flagDisabled_singleCompleteResponse() {
//MdnsScannerConfigsFlagsImpl.allowMultipleSrvRecordsPerHost.override(false);
MdnsResponseDecoder decoder = new MdnsResponseDecoder(mClock, MATTER_SERVICE_TYPE);
assertNotNull(matterDuplicateHostname);
DatagramPacket packet =
new DatagramPacket(matterDuplicateHostname, matterDuplicateHostname.length);
packet.setSocketAddress(
new InetSocketAddress(MdnsConstants.getMdnsIPv6Address(), MdnsConstants.MDNS_PORT));
responses.clear();
int errorCode = decoder.decode(packet, responses, /* interfaceIndex= */ 0);
assertEquals(MdnsResponseDecoder.SUCCESS, errorCode);
// This should emit only two records:
assertEquals(2, responses.size());
// But only the first is complete:
assertTrue(responses.get(0).isComplete());
assertFalse(responses.get(1).isComplete());
}
}