[FUI04] Refactor VpnInfo

As a preparation of exposing system API. This patch does some
harmless refactoring, which includes:
  1. Change raw arrays into lists according to API guidelines.
  2. Write test.
  3. Rename class to UnderlyingNetworkInfo.
  4. Rename vpnIface to iface.
  5. Make underlyingIfaces @NonNull in order to adapt new
     unparceling code.
  6. implement equals and hashCode for testing.

Test: atest android.net.UnderlyingNetworkInfoTest
Bug: 174123988

Change-Id: I405c21e57c4af8a12a9dd0a1749b9e6690f87045

core/java/android/net/INetworkStatsService.aidl

@@ -23,7 +23,7 @@ import android.net.NetworkState;
 import android.net.NetworkStats;
 import android.net.NetworkStatsHistory;
 import android.net.NetworkTemplate;
-import android.net.VpnInfo;
+import android.net.UnderlyingNetworkInfo;
 import android.net.netstats.provider.INetworkStatsProvider;
 import android.net.netstats.provider.INetworkStatsProviderCallback;
 import android.os.IBinder;
@@ -70,7 +70,7 @@ interface INetworkStatsService {
          in Network[] defaultNetworks,
          in NetworkState[] networkStates,
          in String activeIface,
-         in VpnInfo[] vpnInfos);
+         in UnderlyingNetworkInfo[] underlyingNetworkInfos);
     /** Force update of statistics. */
     @UnsupportedAppUsage
     void forceUpdate();

core/java/android/net/UnderlyingNetworkInfo.aidl

@@ -16,4 +16,4 @@
 
 package android.net;
 
-parcelable VpnInfo;
+parcelable UnderlyingNetworkInfo;

core/java/android/net/UnderlyingNetworkInfo.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2015 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;
+
+import android.annotation.NonNull;
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * A lightweight container used to carry information on the networks that underly a given
+ * virtual network.
+ *
+ * @hide
+ */
+public final class UnderlyingNetworkInfo implements Parcelable {
+    /** The owner of this network. */
+    public final int ownerUid;
+    /** The interface name of this network. */
+    @NonNull
+    public final String iface;
+    /** The names of the interfaces underlying this network. */
+    @NonNull
+    public final List<String> underlyingIfaces;
+
+    public UnderlyingNetworkInfo(int ownerUid, @NonNull String iface,
+            @NonNull List<String> underlyingIfaces) {
+        Objects.requireNonNull(iface);
+        Objects.requireNonNull(underlyingIfaces);
+        this.ownerUid = ownerUid;
+        this.iface = iface;
+        this.underlyingIfaces = underlyingIfaces;
+    }
+
+    private UnderlyingNetworkInfo(@NonNull Parcel in) {
+        this.ownerUid = in.readInt();
+        this.iface = in.readString();
+        this.underlyingIfaces = new ArrayList<>();
+        in.readList(this.underlyingIfaces, null /*classLoader*/);
+    }
+
+    @Override
+    public String toString() {
+        return "UnderlyingNetworkInfo{"
+                + "ownerUid=" + ownerUid
+                + ", iface='" + iface + '\''
+                + ", underlyingIfaces='" + underlyingIfaces.toString() + '\''
+                + '}';
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(@NonNull Parcel dest, int flags) {
+        dest.writeInt(ownerUid);
+        dest.writeString(iface);
+        dest.writeList(underlyingIfaces);
+    }
+
+    @NonNull
+    public static final Parcelable.Creator<UnderlyingNetworkInfo> CREATOR =
+            new Parcelable.Creator<UnderlyingNetworkInfo>() {
+        @NonNull
+        @Override
+        public UnderlyingNetworkInfo createFromParcel(@NonNull Parcel in) {
+            return new UnderlyingNetworkInfo(in);
+        }
+
+        @NonNull
+        @Override
+        public UnderlyingNetworkInfo[] newArray(int size) {
+            return new UnderlyingNetworkInfo[size];
+        }
+    };
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof UnderlyingNetworkInfo)) return false;
+        final UnderlyingNetworkInfo that = (UnderlyingNetworkInfo) o;
+        return ownerUid == that.ownerUid
+                && Objects.equals(iface, that.iface)
+                && Objects.equals(underlyingIfaces, that.underlyingIfaces);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(ownerUid, iface, underlyingIfaces);
+    }
+}