Inline tetherInterface and untetherInterface

This is a no-op refactoring which inline the functionalities
to IpServer, enabling subsequent changes to move
networkAddInterface part to ConnectivityService when the
tethering is enabled.

Test: atest TetheringTests:android.net.ip.IpServerTest
      atest NetdStaticLibTests:com.android.net.module.util.NetdUtilsTest
Bug: 349487600

Change-Id: I6d0e5d349691df7a15bee852d5fd1dd19f5da6f6
diff --git a/Tethering/src/android/net/ip/IpServer.java b/Tethering/src/android/net/ip/IpServer.java
index d2fd103..d0ba431 100644
--- a/Tethering/src/android/net/ip/IpServer.java
+++ b/Tethering/src/android/net/ip/IpServer.java
@@ -1125,7 +1125,11 @@
             }
 
             try {
-                NetdUtils.tetherInterface(mNetd, LOCAL_NET_ID, mIfaceName);
+                // Enable IPv6, disable accepting RA, etc. See TetherController::tetherInterface()
+                // for more detail.
+                mNetd.tetherInterfaceAdd(mIfaceName);
+                NetdUtils.networkAddInterface(mNetd, LOCAL_NET_ID, mIfaceName,
+                        20 /* maxAttempts */, 50 /* pollingIntervalMs */);
                 // Activate a route to dest and IPv6 link local.
                 NetdUtils.modifyRoute(mNetd, NetdUtils.ModifyOperation.ADD, LOCAL_NET_ID,
                         new RouteInfo(asIpPrefix(mIpv4Address), null, mIfaceName, RTN_UNICAST));
@@ -1152,8 +1156,13 @@
             // all in sequence.
             stopIPv6();
 
+            // Reset interface for tethering.
             try {
-                NetdUtils.untetherInterface(mNetd, LOCAL_NET_ID, mIfaceName);
+                try {
+                    mNetd.tetherInterfaceRemove(mIfaceName);
+                } finally {
+                    mNetd.networkRemoveInterface(LOCAL_NET_ID, mIfaceName);
+                }
             } catch (RemoteException | ServiceSpecificException e) {
                 mLastError = TETHER_ERROR_UNTETHER_IFACE_ERROR;
                 mLog.e("Failed to untether interface: " + e);
diff --git a/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java b/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java
index 7e261ba..4af516d 100644
--- a/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java
+++ b/staticlibs/client-libs/netd/com/android/net/module/util/NetdUtils.java
@@ -148,20 +148,6 @@
         netd.tetherStartWithConfiguration(config);
     }
 
-    /** Setup interface for tethering. */
-    public static void tetherInterface(final INetd netd, int netId, final String iface)
-            throws RemoteException, ServiceSpecificException {
-        tetherInterface(netd, netId, iface, 20 /* maxAttempts */, 50 /* pollingIntervalMs */);
-    }
-
-    /** Setup interface with configurable retries for tethering. */
-    public static void tetherInterface(final INetd netd, int netId, final String iface,
-            int maxAttempts, int pollingIntervalMs)
-            throws RemoteException, ServiceSpecificException {
-        netd.tetherInterfaceAdd(iface);
-        networkAddInterface(netd, netId, iface, maxAttempts, pollingIntervalMs);
-    }
-
     /**
      * Retry Netd#networkAddInterface for EBUSY error code.
      * If the same interface (e.g., wlan0) is in client mode and then switches to tethered mode.
@@ -169,7 +155,7 @@
      * in use in netd because the ConnectivityService thread hasn't processed the disconnect yet.
      * See b/158269544 for detail.
      */
-    private static void networkAddInterface(final INetd netd, int netId, final String iface,
+    public static void networkAddInterface(final INetd netd, int netId, final String iface,
             int maxAttempts, int pollingIntervalMs)
             throws ServiceSpecificException, RemoteException {
         for (int i = 1; i <= maxAttempts; i++) {
@@ -188,16 +174,6 @@
         }
     }
 
-    /** Reset interface for tethering. */
-    public static void untetherInterface(final INetd netd, int netId, String iface)
-            throws RemoteException, ServiceSpecificException {
-        try {
-            netd.tetherInterfaceRemove(iface);
-        } finally {
-            netd.networkRemoveInterface(netId, iface);
-        }
-    }
-
     /** Add |routes| to the given network. */
     public static void addRoutesToNetwork(final INetd netd, int netId, final String iface,
             final List<RouteInfo> routes) {
diff --git a/staticlibs/client-libs/tests/unit/src/com/android/net/module/util/NetdUtilsTest.java b/staticlibs/client-libs/tests/unit/src/com/android/net/module/util/NetdUtilsTest.java
index 03128fa..0241d0a 100644
--- a/staticlibs/client-libs/tests/unit/src/com/android/net/module/util/NetdUtilsTest.java
+++ b/staticlibs/client-libs/tests/unit/src/com/android/net/module/util/NetdUtilsTest.java
@@ -24,13 +24,9 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
-import static org.mockito.ArgumentMatchers.any;
-import static org.mockito.ArgumentMatchers.anyInt;
-import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.doAnswer;
-import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -148,20 +144,21 @@
     }
 
     @Test
-    public void testTetherInterfaceSuccessful() throws Exception {
+    public void testNetworkAddInterfaceSuccessful() throws Exception {
         // Expect #networkAddInterface successful at first tries.
-        verifyTetherInterfaceSucceeds(1);
+        verifyNetworkAddInterfaceSucceeds(1);
 
         // Expect #networkAddInterface successful after 10 tries.
-        verifyTetherInterfaceSucceeds(10);
+        verifyNetworkAddInterfaceSucceeds(10);
     }
 
-    private void runTetherInterfaceWithServiceSpecificException(int expectedTries,
+    private void runNetworkAddInterfaceWithServiceSpecificException(int expectedTries,
             int expectedCode) throws Exception {
         setNetworkAddInterfaceOutcome(new ServiceSpecificException(expectedCode), expectedTries);
 
         try {
-            NetdUtils.tetherInterface(mNetd, TEST_NET_ID, IFACE, 20, 0);
+            NetdUtils.networkAddInterface(mNetd, TEST_NET_ID, IFACE,
+                    20 /* maxAttempts */, 0 /* pollingIntervalMs */);
             fail("Expect throw ServiceSpecificException");
         } catch (ServiceSpecificException e) {
             assertEquals(e.errorCode, expectedCode);
@@ -171,11 +168,12 @@
         reset(mNetd);
     }
 
-    private void runTetherInterfaceWithRemoteException(int expectedTries) throws Exception {
+    private void runNetworkAddInterfaceWithRemoteException(int expectedTries) throws Exception {
         setNetworkAddInterfaceOutcome(new RemoteException(), expectedTries);
 
         try {
-            NetdUtils.tetherInterface(mNetd, TEST_NET_ID, IFACE, 20, 0);
+            NetdUtils.networkAddInterface(mNetd, TEST_NET_ID, IFACE,
+                    20 /* maxAttempts */, 0 /* pollingIntervalMs */);
             fail("Expect throw RemoteException");
         } catch (RemoteException e) { }
 
@@ -184,40 +182,37 @@
     }
 
     private void verifyNetworkAddInterfaceFails(int expectedTries) throws Exception {
-        verify(mNetd).tetherInterfaceAdd(IFACE);
         verify(mNetd, times(expectedTries)).networkAddInterface(TEST_NET_ID, IFACE);
-        verify(mNetd, never()).networkAddRoute(anyInt(), anyString(), any(), any());
-
         verifyNoMoreInteractions(mNetd);
     }
 
-    private void verifyTetherInterfaceSucceeds(int expectedTries) throws Exception {
+    private void verifyNetworkAddInterfaceSucceeds(int expectedTries) throws Exception {
         setNetworkAddInterfaceOutcome(null, expectedTries);
 
-        NetdUtils.tetherInterface(mNetd, TEST_NET_ID, IFACE);
-        verify(mNetd).tetherInterfaceAdd(IFACE);
+        NetdUtils.networkAddInterface(mNetd, TEST_NET_ID, IFACE,
+                20 /* maxAttempts */, 0 /* pollingIntervalMs */);
         verify(mNetd, times(expectedTries)).networkAddInterface(TEST_NET_ID, IFACE);
         verifyNoMoreInteractions(mNetd);
         reset(mNetd);
     }
 
     @Test
-    public void testTetherInterfaceFailOnNetworkAddInterface() throws Exception {
+    public void testFailOnNetworkAddInterface() throws Exception {
         // Test throwing ServiceSpecificException with EBUSY failure.
-        runTetherInterfaceWithServiceSpecificException(20, EBUSY);
+        runNetworkAddInterfaceWithServiceSpecificException(20, EBUSY);
 
         // Test throwing ServiceSpecificException with unexpectedError.
         final int unexpectedError = 999;
-        runTetherInterfaceWithServiceSpecificException(1, unexpectedError);
+        runNetworkAddInterfaceWithServiceSpecificException(1, unexpectedError);
 
         // Test throwing ServiceSpecificException with unexpectedError after 7 tries.
-        runTetherInterfaceWithServiceSpecificException(7, unexpectedError);
+        runNetworkAddInterfaceWithServiceSpecificException(7, unexpectedError);
 
         // Test throwing RemoteException.
-        runTetherInterfaceWithRemoteException(1);
+        runNetworkAddInterfaceWithRemoteException(1);
 
         // Test throwing RemoteException after 3 tries.
-        runTetherInterfaceWithRemoteException(3);
+        runNetworkAddInterfaceWithRemoteException(3);
     }
 
     @Test