Fix service resolve on tethering downstreams

Tethering downstreams do not have NetworkAgents, and although they have
a netid of 99, Networks with netId 99 are not usable by apps for most
connectivity APIs.

Recent refactoring in NsdService adds the Network of a found service
into its NsdServiceInfo, and uses that network to resolve the service.
In that case the Network has netId 99 and resolving the service fails.

Avoid that problem by:
 - Keeping the Network field null when a service is found on a tethering
   downstream; this avoids giving apps a confusing and unusable Network
   with netId 99
 - Using the interface index found during discovery to resolve the
   service, if the app uses the NsdServiceInfo that was obtained from
   discovery to resolve. If not, all interfaces will be used to resolve,
   as per legacy APIs.

Bug: 233979892
Test: atest NsdServiceTest
      Also manual test with 2 devices connected via hotspot
Change-Id: Idd176153b67ccbd1d4f1b1fd66dafaa2f3a9e27a
(cherry picked from commit 1a8ee102d3cc9829b669b09685b17ea92815b671)
Merged-In: Idd176153b67ccbd1d4f1b1fd66dafaa2f3a9e27a

1 files changed, 108 insertions, 0 deletions

diff --git a/tests/unit/java/com/android/server/NsdServiceTest.java b/tests/unit/java/com/android/server/NsdServiceTest.java
index 3c228d0609..ed9e930500 100644
--- a/tests/unit/java/com/android/server/NsdServiceTest.java
+++ b/tests/unit/java/com/android/server/NsdServiceTest.java
@@ -19,7 +19,9 @@ package com.android.server;
 import static libcore.junit.util.compat.CoreCompatChangeRule.DisableCompatChanges;
 import static libcore.junit.util.compat.CoreCompatChangeRule.EnableCompatChanges;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.any;
@@ -36,6 +38,12 @@ import static org.mockito.Mockito.when;
 import android.compat.testing.PlatformCompatChangeRule;
 import android.content.ContentResolver;
 import android.content.Context;
+import android.net.INetd;
+import android.net.InetAddresses;
+import android.net.mdns.aidl.DiscoveryInfo;
+import android.net.mdns.aidl.GetAddressInfo;
+import android.net.mdns.aidl.IMDnsEventListener;
+import android.net.mdns.aidl.ResolutionInfo;
 import android.net.nsd.INsdManagerCallback;
 import android.net.nsd.INsdServiceConnector;
 import android.net.nsd.MDnsManager;
@@ -63,6 +71,7 @@ import org.junit.Test;
 import org.junit.rules.TestRule;
 import org.junit.runner.RunWith;
 import org.mockito.AdditionalAnswers;
+import org.mockito.ArgumentCaptor;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
@@ -275,6 +284,105 @@ public class NsdServiceTest {
         verify(mMockMDnsM, never()).stopDaemon();
     }
 
+    @Test
+    public void testDiscoverOnTetheringDownstream() throws Exception {
+        NsdService service = makeService();
+        NsdManager client = connectClient(service);
+
+        final String serviceType = "a_type";
+        final String serviceName = "a_name";
+        final String domainName = "mytestdevice.local";
+        final int interfaceIdx = 123;
+        final NsdManager.DiscoveryListener discListener = mock(NsdManager.DiscoveryListener.class);
+        client.discoverServices(serviceType, NsdManager.PROTOCOL_DNS_SD, discListener);
+        waitForIdle();
+
+        final ArgumentCaptor<IMDnsEventListener> listenerCaptor =
+                ArgumentCaptor.forClass(IMDnsEventListener.class);
+        verify(mMockMDnsM).registerEventListener(listenerCaptor.capture());
+        final ArgumentCaptor<Integer> discIdCaptor = ArgumentCaptor.forClass(Integer.class);
+        verify(mMockMDnsM).discover(discIdCaptor.capture(), eq(serviceType),
+                eq(0) /* interfaceIdx */);
+        // NsdManager uses a separate HandlerThread to dispatch callbacks (on ServiceHandler), so
+        // this needs to use a timeout
+        verify(discListener, timeout(TIMEOUT_MS)).onDiscoveryStarted(serviceType);
+
+        final DiscoveryInfo discoveryInfo = new DiscoveryInfo(
+                discIdCaptor.getValue(),
+                IMDnsEventListener.SERVICE_FOUND,
+                serviceName,
+                serviceType,
+                domainName,
+                interfaceIdx,
+                INetd.LOCAL_NET_ID); // LOCAL_NET_ID (99) used on tethering downstreams
+        final IMDnsEventListener eventListener = listenerCaptor.getValue();
+        eventListener.onServiceDiscoveryStatus(discoveryInfo);
+        waitForIdle();
+
+        final ArgumentCaptor<NsdServiceInfo> discoveredInfoCaptor =
+                ArgumentCaptor.forClass(NsdServiceInfo.class);
+        verify(discListener, timeout(TIMEOUT_MS)).onServiceFound(discoveredInfoCaptor.capture());
+        final NsdServiceInfo foundInfo = discoveredInfoCaptor.getValue();
+        assertEquals(serviceName, foundInfo.getServiceName());
+        assertEquals(serviceType, foundInfo.getServiceType());
+        assertNull(foundInfo.getHost());
+        assertNull(foundInfo.getNetwork());
+        assertEquals(interfaceIdx, foundInfo.getInterfaceIndex());
+
+        // After discovering the service, verify resolving it
+        final NsdManager.ResolveListener resolveListener = mock(NsdManager.ResolveListener.class);
+        client.resolveService(foundInfo, resolveListener);
+        waitForIdle();
+
+        final ArgumentCaptor<Integer> resolvIdCaptor = ArgumentCaptor.forClass(Integer.class);
+        verify(mMockMDnsM).resolve(resolvIdCaptor.capture(), eq(serviceName), eq(serviceType),
+                eq("local.") /* domain */, eq(interfaceIdx));
+
+        final int servicePort = 10123;
+        final String serviceFullName = serviceName + "." + serviceType;
+        final ResolutionInfo resolutionInfo = new ResolutionInfo(
+                resolvIdCaptor.getValue(),
+                IMDnsEventListener.SERVICE_RESOLVED,
+                null /* serviceName */,
+                null /* serviceType */,
+                null /* domain */,
+                serviceFullName,
+                domainName,
+                servicePort,
+                new byte[0] /* txtRecord */,
+                interfaceIdx);
+
+        doReturn(true).when(mMockMDnsM).getServiceAddress(anyInt(), any(), anyInt());
+        eventListener.onServiceResolutionStatus(resolutionInfo);
+        waitForIdle();
+
+        final ArgumentCaptor<Integer> getAddrIdCaptor = ArgumentCaptor.forClass(Integer.class);
+        verify(mMockMDnsM).getServiceAddress(getAddrIdCaptor.capture(), eq(domainName),
+                eq(interfaceIdx));
+
+        final String serviceAddress = "192.0.2.123";
+        final GetAddressInfo addressInfo = new GetAddressInfo(
+                getAddrIdCaptor.getValue(),
+                IMDnsEventListener.SERVICE_GET_ADDR_SUCCESS,
+                serviceFullName,
+                serviceAddress,
+                interfaceIdx,
+                INetd.LOCAL_NET_ID);
+        eventListener.onGettingServiceAddressStatus(addressInfo);
+        waitForIdle();
+
+        final ArgumentCaptor<NsdServiceInfo> resInfoCaptor =
+                ArgumentCaptor.forClass(NsdServiceInfo.class);
+        verify(resolveListener, timeout(TIMEOUT_MS)).onServiceResolved(resInfoCaptor.capture());
+        final NsdServiceInfo resolvedService = resInfoCaptor.getValue();
+        assertEquals(serviceName, resolvedService.getServiceName());
+        assertEquals("." + serviceType, resolvedService.getServiceType());
+        assertEquals(InetAddresses.parseNumericAddress(serviceAddress), resolvedService.getHost());
+        assertEquals(servicePort, resolvedService.getPort());
+        assertNull(resolvedService.getNetwork());
+        assertEquals(interfaceIdx, resolvedService.getInterfaceIndex());
+    }
+
     private void waitForIdle() {
         HandlerUtils.waitForIdle(mHandler, TIMEOUT_MS);
     }