Add CTS to verify VCN can exit safe mode

Bug:391977557
Flag: EXEMPT test code
Test: CtsVcnTestCases(new test added)
Change-Id: I8fdb2d643fc419024cd5609dff79336f4ab5cb96

Vcn/tests/cts/src/android/net/vcn/cts/VcnManagerTest.java

@@ -207,6 +207,13 @@ public class VcnManagerTest extends VcnTestBase {
                                 .build());
     }
 
+    private VcnConfig buildVcnConfig(VcnGatewayConnectionConfig gatewayConfig) {
+        return new VcnConfig.Builder(mContext)
+                .setIsTestModeProfile()
+                .addGatewayConnectionConfig(gatewayConfig)
+                .build();
+    }
+
     private VcnConfig buildVcnConfig() {
         return buildVcnConfigBase().build();
     }
@@ -1454,4 +1461,84 @@ public class VcnManagerTest extends VcnTestBase {
         verifyEnterSafeModeImmediately(
                 newVcnConfig(false /* isSafeModeEnabled */), false /* isSafeModeExpected */);
     }
+
+    // Test for b/391977557
+    @Test
+    public void testExitSafeModeAfterReprovision() throws Exception {
+        final int subId = verifyAndGetValidDataSubId();
+
+        // Create a VcnGatewayConnectionConfig with a big retry timer to avoid retry and sending IKE
+        // INIT requests after entering safe mode
+        final VcnGatewayConnectionConfig.Builder gatewayConfigBuilder =
+                VcnGatewayConnectionConfigTest.buildVcnGatewayConnectionConfigBase()
+                        .setRetryIntervalsMillis(new long[] {TimeUnit.MINUTES.toMillis(100)});
+
+        // Create two different VcnConfigs that will trigger the previous safe mode exit issue
+        // b/391977557
+        final VcnConfig vcnConfig = buildVcnConfig(gatewayConfigBuilder.setMaxMtu(1500).build());
+        final VcnConfig vcnConfigNew = buildVcnConfig(gatewayConfigBuilder.setMaxMtu(1600).build());
+
+        // Generated by forcing IKE to use Test Mode (RandomnessFactory#mIsTestModeEnabled) and
+        // capturing IKE packets with a live server.
+        final String ikeInitFailRespHex =
+                "46B8ECA1E0D72A180000000000000000292022200000000000000024000000080000000E";
+
+        final NetworkRequest cellNetworkReq =
+                new NetworkRequest.Builder()
+                        .addTransportType(TRANSPORT_CELLULAR)
+                        .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
+                        .build();
+        final VcnTestNetworkCallback cellNetworkCbPostSafeMode = new VcnTestNetworkCallback();
+
+        try (TestNetworkWrapper testNetworkWrapper =
+                createTestNetworkWrapper(true /* isMetered */, subId, LOCAL_ADDRESS)) {
+            verifyUnderlyingCellAndRunTest(
+                    subId,
+                    (subGrp, cellNetwork, cellNetworkCb) -> {
+                        mVcnManager.setVcnConfig(subGrp, vcnConfig);
+
+                        // Inject an IKE INIT FAIL response to fail the IKE setup
+                        testNetworkWrapper.ikeTunUtils.awaitReqAndInjectResp(
+                                IKE_DETERMINISTIC_INITIATOR_SPI,
+                                0 /* expectedMsgId */,
+                                false /* expectedUseEncap */,
+                                ikeInitFailRespHex);
+
+                        waitForSafeMode(testNetworkWrapper);
+                        verifyVcnStatus(subGrp, VCN_STATUS_CODE_SAFE_MODE);
+
+                        // Register a NetworkCallback to detect when a cell network becomes
+                        // available. This callback also acts as a signaler to proceed with the test
+                        // because, if b/391977557 exists, its symptom (the withdrawal of all
+                        // existing NetworkRequests from VCN) will have *already completed* by
+                        // the time a cell network becomes available.
+                        mConnectivityManager.registerNetworkCallback(
+                                cellNetworkReq, cellNetworkCbPostSafeMode);
+                        assertNotNull(
+                                "No cell network found after entering safe mode",
+                                cellNetworkCbPostSafeMode.waitForAvailable());
+
+                        // Before verifying new IKE setup triggered by reprovision, clear the IKE
+                        // requests generated from the previous setup. Because the failed VCN
+                        // connection is configured to never retry, it's safe to conclude that any
+                        // new IKE requests are generated by the second setup.
+                        testNetworkWrapper.ikeTunUtils.reset();
+                        mVcnManager.setVcnConfig(subGrp, vcnConfigNew);
+
+                        injectAndVerifyIkeSessionNegotiationPackets(testNetworkWrapper.ikeTunUtils);
+
+                        // Because the VCN network established by the test will never pass the
+                        // system network validation, VCN will never really exit safe mode in the
+                        // test. However, the establishment of the VCN network provides enough
+                        // confidence that in real case the VCN will be able to exit safe mode.
+                        final Network vcnNetwork = cellNetworkCbPostSafeMode.waitForAvailable();
+                        assertNotNull("VCN network did not come up", vcnNetwork);
+
+                        clearVcnConfigsAndVerifyNetworkTeardown(
+                                subGrp, cellNetworkCbPostSafeMode, vcnNetwork);
+
+                        mConnectivityManager.unregisterNetworkCallback(cellNetworkCbPostSafeMode);
+                    });
+        }
+    }
 }