Add VcnUnderlyingNetworkSpecifier

This change adds a VcnUnderlyingNetworkSpecifier as hidden API, for
internal use only. The purpose of the VcnUnderlyingNetworkSpecifier is to
match the specifiers for ONLY underlying (Telephony|Wifi) networks,
ensuring that the VCN does NOT create a routing loop

Bug: 179439329
Test: atest FrameworksVcnTests
Test: atest android.net.vcn
Change-Id: I0e158e1889d4462c117c46d9038f58d5adcc7e30

3 files changed, 186 insertions, 2 deletions

diff --git a/core/java/android/net/vcn/VcnUnderlyingNetworkSpecifier.java b/core/java/android/net/vcn/VcnUnderlyingNetworkSpecifier.java
new file mode 100644
index 000000000000..a97563724e50
--- /dev/null
+++ b/core/java/android/net/vcn/VcnUnderlyingNetworkSpecifier.java
@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2021 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 android.net.vcn;
+
+import android.annotation.NonNull;
+import android.net.NetworkSpecifier;
+import android.net.TelephonyNetworkSpecifier;
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.annotations.VisibleForTesting.Visibility;
+import com.android.internal.util.ArrayUtils;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+/**
+ * NetworkSpecifier object for VCN underlying network requests.
+ *
+ * <p>This matches any underlying network with the appropriate subIds.
+ *
+ * @hide
+ */
+public final class VcnUnderlyingNetworkSpecifier extends NetworkSpecifier implements Parcelable {
+    @NonNull private final int[] mSubIds;
+
+    /**
+     * Builds a new VcnUnderlyingNetworkSpecifier with the given list of subIds
+     *
+     * @hide
+     */
+    public VcnUnderlyingNetworkSpecifier(@NonNull int[] subIds) {
+        mSubIds = Objects.requireNonNull(subIds, "subIds were null");
+    }
+
+    /**
+     * Retrieves the list of subIds supported by this VcnUnderlyingNetworkSpecifier
+     *
+     * @hide
+     */
+    @NonNull
+    @VisibleForTesting(visibility = Visibility.PRIVATE)
+    public int[] getSubIds() {
+        return mSubIds;
+    }
+
+    public static final @NonNull Creator<VcnUnderlyingNetworkSpecifier> CREATOR =
+            new Creator<VcnUnderlyingNetworkSpecifier>() {
+                @Override
+                public VcnUnderlyingNetworkSpecifier createFromParcel(Parcel in) {
+                    int[] subIds = in.createIntArray();
+                    return new VcnUnderlyingNetworkSpecifier(subIds);
+                }
+
+                @Override
+                public VcnUnderlyingNetworkSpecifier[] newArray(int size) {
+                    return new VcnUnderlyingNetworkSpecifier[size];
+                }
+            };
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(@NonNull Parcel dest, int flags) {
+        dest.writeIntArray(mSubIds);
+    }
+
+    @Override
+    public int hashCode() {
+        return Arrays.hashCode(mSubIds);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (!(obj instanceof VcnUnderlyingNetworkSpecifier)) {
+            return false;
+        }
+
+        VcnUnderlyingNetworkSpecifier lhs = (VcnUnderlyingNetworkSpecifier) obj;
+        return Arrays.equals(mSubIds, lhs.mSubIds);
+    }
+
+    @Override
+    public String toString() {
+        return new StringBuilder()
+                .append("VcnUnderlyingNetworkSpecifier [")
+                .append("mSubIds = ").append(Arrays.toString(mSubIds))
+                .append("]")
+                .toString();
+    }
+
+    /** @hide */
+    @Override
+    public boolean canBeSatisfiedBy(NetworkSpecifier other) {
+        if (other instanceof TelephonyNetworkSpecifier) {
+            return ArrayUtils.contains(
+                    mSubIds, ((TelephonyNetworkSpecifier) other).getSubscriptionId());
+        }
+        // TODO(b/180140053): Allow matching against WifiNetworkAgentSpecifier
+
+        // MatchAllNetworkSpecifier matched in NetworkCapabilities.
+        return equals(other);
+    }
+}
diff --git a/services/core/java/com/android/server/vcn/VcnGatewayConnection.java b/services/core/java/com/android/server/vcn/VcnGatewayConnection.java
index 37d13fb86dc0..ee36333eaadb 100644
--- a/services/core/java/com/android/server/vcn/VcnGatewayConnection.java
+++ b/services/core/java/com/android/server/vcn/VcnGatewayConnection.java
@@ -1326,8 +1326,6 @@ public class VcnGatewayConnection extends StateMachine {
             }
         }
 
-        // TODO: Make a VcnNetworkSpecifier, and match all underlying subscription IDs.
-
         return builder.build();
     }
 
diff --git a/tests/vcn/java/android/net/vcn/VcnUnderlyingNetworkSpecifierTest.java b/tests/vcn/java/android/net/vcn/VcnUnderlyingNetworkSpecifierTest.java
new file mode 100644
index 000000000000..2110d6ee7c86
--- /dev/null
+++ b/tests/vcn/java/android/net/vcn/VcnUnderlyingNetworkSpecifierTest.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2021 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 android.net.vcn;
+
+import static com.android.testutils.ParcelUtils.assertParcelSane;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import android.net.TelephonyNetworkSpecifier;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class VcnUnderlyingNetworkSpecifierTest {
+    private static final int[] TEST_SUB_IDS = new int[] {1, 2, 3, 5};
+
+    @Test
+    public void testGetSubIds() {
+        final VcnUnderlyingNetworkSpecifier specifier =
+                new VcnUnderlyingNetworkSpecifier(TEST_SUB_IDS);
+
+        assertEquals(TEST_SUB_IDS, specifier.getSubIds());
+    }
+
+    @Test
+    public void testParceling() {
+        final VcnUnderlyingNetworkSpecifier specifier =
+                new VcnUnderlyingNetworkSpecifier(TEST_SUB_IDS);
+        assertParcelSane(specifier, 1);
+    }
+
+    @Test
+    public void testCanBeSatisfiedByTelephonyNetworkSpecifier() {
+        final TelephonyNetworkSpecifier telSpecifier =
+                new TelephonyNetworkSpecifier(TEST_SUB_IDS[0]);
+
+        final VcnUnderlyingNetworkSpecifier specifier =
+                new VcnUnderlyingNetworkSpecifier(TEST_SUB_IDS);
+        assertTrue(specifier.canBeSatisfiedBy(telSpecifier));
+    }
+}