Add an API that allows VPNs to declare themselves as metered.

For VPN apps targeting Q and above, they will by default be treated as
metered unless they override this setting before establishing VPN.

Bug: 120145746
Test: atest FrameworksNetTests
Test: On device tests verifying meteredness setup correctly for apps
targeting Q and apps targeting P.
Change-Id: Ia6d1f7ef244bc04ae2e28faa59625302b5994875
diff --git a/api/current.txt b/api/current.txt
index bb40056..e248d71 100755
--- a/api/current.txt
+++ b/api/current.txt
@@ -27851,6 +27851,7 @@
     method public android.net.VpnService.Builder setBlocking(boolean);
     method public android.net.VpnService.Builder setConfigureIntent(android.app.PendingIntent);
     method public android.net.VpnService.Builder setHttpProxy(android.net.ProxyInfo);
+    method public android.net.VpnService.Builder setMetered(boolean);
     method public android.net.VpnService.Builder setMtu(int);
     method public android.net.VpnService.Builder setSession(String);
     method public android.net.VpnService.Builder setUnderlyingNetworks(android.net.Network[]);
diff --git a/core/java/android/net/VpnService.java b/core/java/android/net/VpnService.java
index dc099a4..784f233 100644
--- a/core/java/android/net/VpnService.java
+++ b/core/java/android/net/VpnService.java
@@ -791,6 +791,27 @@
         }
 
         /**
+         * Marks the VPN network as metered. A VPN network is classified as metered when the user is
+         * sensitive to heavy data usage due to monetary costs and/or data limitations. In such
+         * cases, you should set this to {@code true} so that apps on the system can avoid doing
+         * large data transfers. Otherwise, set this to {@code false}. Doing so would cause VPN
+         * network to inherit its meteredness from its underlying networks.
+         *
+         * <p>VPN apps targeting {@link android.os.Build.VERSION_CODES#Q} or above will be
+         * considered metered by default.
+         *
+         * @param isMetered {@code true} if VPN network should be treated as metered regardless of
+         *     underlying network meteredness
+         * @return this {@link Builder} object to facilitate chaining method calls
+         * @see #setUnderlyingNetworks(Networks[])
+         * @see ConnectivityManager#isActiveNetworkMetered()
+         */
+        public Builder setMetered(boolean isMetered) {
+            mConfig.isMetered = isMetered;
+            return this;
+        }
+
+        /**
          * Create a VPN interface using the parameters supplied to this
          * builder. The interface works on IP packets, and a file descriptor
          * is returned for the application to access them. Each read
diff --git a/core/java/com/android/internal/net/VpnConfig.java b/core/java/com/android/internal/net/VpnConfig.java
index da8605e..65b974b 100644
--- a/core/java/com/android/internal/net/VpnConfig.java
+++ b/core/java/com/android/internal/net/VpnConfig.java
@@ -104,6 +104,7 @@
     public boolean allowBypass;
     public boolean allowIPv4;
     public boolean allowIPv6;
+    public boolean isMetered = true;
     public Network[] underlyingNetworks;
     public ProxyInfo proxyInfo;
 
@@ -165,6 +166,7 @@
         out.writeInt(allowBypass ? 1 : 0);
         out.writeInt(allowIPv4 ? 1 : 0);
         out.writeInt(allowIPv6 ? 1 : 0);
+        out.writeInt(isMetered ? 1 : 0);
         out.writeTypedArray(underlyingNetworks, flags);
         out.writeParcelable(proxyInfo, flags);
     }
@@ -191,6 +193,7 @@
             config.allowBypass = in.readInt() != 0;
             config.allowIPv4 = in.readInt() != 0;
             config.allowIPv6 = in.readInt() != 0;
+            config.isMetered = in.readInt() != 0;
             config.underlyingNetworks = in.createTypedArray(Network.CREATOR);
             config.proxyInfo = in.readParcelable(null);
             return config;
diff --git a/services/core/java/com/android/server/connectivity/Vpn.java b/services/core/java/com/android/server/connectivity/Vpn.java
index 2508844..9141ccb 100644
--- a/services/core/java/com/android/server/connectivity/Vpn.java
+++ b/services/core/java/com/android/server/connectivity/Vpn.java
@@ -165,6 +165,7 @@
     private final NetworkInfo mNetworkInfo;
     private String mPackage;
     private int mOwnerUID;
+    private boolean mIsPackageTargetingAtLeastQ;
     private String mInterface;
     private Connection mConnection;
     private LegacyVpnRunner mLegacyVpnRunner;
@@ -226,6 +227,7 @@
 
         mPackage = VpnConfig.LEGACY_VPN;
         mOwnerUID = getAppUid(mPackage, mUserHandle);
+        mIsPackageTargetingAtLeastQ = doesPackageTargetAtLeastQ(mPackage);
 
         try {
             netService.registerObserver(mObserver);
@@ -267,8 +269,11 @@
 
     public void updateCapabilities() {
         final Network[] underlyingNetworks = (mConfig != null) ? mConfig.underlyingNetworks : null;
+        // Only apps targeting Q and above can explicitly declare themselves as metered.
+        final boolean isAlwaysMetered =
+                mIsPackageTargetingAtLeastQ && (mConfig == null || mConfig.isMetered);
         updateCapabilities(mContext.getSystemService(ConnectivityManager.class), underlyingNetworks,
-                mNetworkCapabilities);
+                mNetworkCapabilities, isAlwaysMetered);
 
         if (mNetworkAgent != null) {
             mNetworkAgent.sendNetworkCapabilities(mNetworkCapabilities);
@@ -277,11 +282,13 @@
 
     @VisibleForTesting
     public static void updateCapabilities(ConnectivityManager cm, Network[] underlyingNetworks,
-            NetworkCapabilities caps) {
+            NetworkCapabilities caps, boolean isAlwaysMetered) {
         int[] transportTypes = new int[] { NetworkCapabilities.TRANSPORT_VPN };
         int downKbps = NetworkCapabilities.LINK_BANDWIDTH_UNSPECIFIED;
         int upKbps = NetworkCapabilities.LINK_BANDWIDTH_UNSPECIFIED;
-        boolean metered = false;
+        // VPN's meteredness is OR'd with isAlwaysMetered and meteredness of its underlying
+        // networks.
+        boolean metered = isAlwaysMetered;
         boolean roaming = false;
         boolean congested = false;
 
@@ -724,6 +731,7 @@
             Log.i(TAG, "Switched from " + mPackage + " to " + newPackage);
             mPackage = newPackage;
             mOwnerUID = getAppUid(newPackage, mUserHandle);
+            mIsPackageTargetingAtLeastQ = doesPackageTargetAtLeastQ(newPackage);
             try {
                 mNetd.allowProtect(mOwnerUID);
             } catch (Exception e) {
@@ -789,6 +797,21 @@
         return result;
     }
 
+    private boolean doesPackageTargetAtLeastQ(String packageName) {
+        if (VpnConfig.LEGACY_VPN.equals(packageName)) {
+            return true;
+        }
+        PackageManager pm = mContext.getPackageManager();
+        try {
+            ApplicationInfo appInfo =
+                    pm.getApplicationInfoAsUser(packageName, 0 /*flags*/, mUserHandle);
+            return appInfo.targetSdkVersion >= VERSION_CODES.Q;
+        } catch (NameNotFoundException unused) {
+            Log.w(TAG, "Can't find \"" + packageName + "\"");
+            return false;
+        }
+    }
+
     public NetworkInfo getNetworkInfo() {
         return mNetworkInfo;
     }
@@ -1076,6 +1099,8 @@
                 // as rules are deleted. This prevents data leakage as the rules are moved over.
                 agentDisconnect(oldNetworkAgent);
             }
+            // Set up VPN's capabilities such as meteredness.
+            updateCapabilities();
 
             if (oldConnection != null) {
                 mContext.unbindService(oldConnection);
@@ -1776,6 +1801,7 @@
         config.user = profile.key;
         config.interfaze = iface;
         config.session = profile.name;
+        config.isMetered = false;
 
         config.addLegacyRoutes(profile.routes);
         if (!profile.dnsServers.isEmpty()) {
diff --git a/tests/net/java/com/android/server/ConnectivityServiceTest.java b/tests/net/java/com/android/server/ConnectivityServiceTest.java
index 923c7dd..67fe8e55 100644
--- a/tests/net/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/net/java/com/android/server/ConnectivityServiceTest.java
@@ -903,6 +903,7 @@
             mNetworkCapabilities.set(mMockNetworkAgent.getNetworkCapabilities());
             mConnected = true;
             mConfig = new VpnConfig();
+            mConfig.isMetered = false;
         }
 
         @Override
diff --git a/tests/net/java/com/android/server/connectivity/VpnTest.java b/tests/net/java/com/android/server/connectivity/VpnTest.java
index 5b17224..46de3d0 100644
--- a/tests/net/java/com/android/server/connectivity/VpnTest.java
+++ b/tests/net/java/com/android/server/connectivity/VpnTest.java
@@ -168,6 +168,8 @@
         ApplicationInfo applicationInfo = new ApplicationInfo();
         applicationInfo.targetSdkVersion = VERSION_CODES.CUR_DEVELOPMENT;
         when(mContext.getApplicationInfo()).thenReturn(applicationInfo);
+        when(mPackageManager.getApplicationInfoAsUser(anyString(), anyInt(), anyInt()))
+                .thenReturn(applicationInfo);
 
         doNothing().when(mNetService).registerObserver(any());
     }
@@ -544,23 +546,28 @@
         final Network wifi = new Network(2);
 
         final Map<Network, NetworkCapabilities> networks = new HashMap<>();
-        networks.put(mobile, new NetworkCapabilities()
-                .addTransportType(TRANSPORT_CELLULAR)
-                .addCapability(NET_CAPABILITY_INTERNET)
-                .addCapability(NET_CAPABILITY_NOT_METERED)
-                .addCapability(NET_CAPABILITY_NOT_CONGESTED)
-                .setLinkDownstreamBandwidthKbps(10));
-        networks.put(wifi, new NetworkCapabilities()
-                .addTransportType(TRANSPORT_WIFI)
-                .addCapability(NET_CAPABILITY_INTERNET)
-                .addCapability(NET_CAPABILITY_NOT_ROAMING)
-                .addCapability(NET_CAPABILITY_NOT_CONGESTED)
-                .setLinkUpstreamBandwidthKbps(20));
+        networks.put(
+                mobile,
+                new NetworkCapabilities()
+                        .addTransportType(TRANSPORT_CELLULAR)
+                        .addCapability(NET_CAPABILITY_INTERNET)
+                        .addCapability(NET_CAPABILITY_NOT_CONGESTED)
+                        .setLinkDownstreamBandwidthKbps(10));
+        networks.put(
+                wifi,
+                new NetworkCapabilities()
+                        .addTransportType(TRANSPORT_WIFI)
+                        .addCapability(NET_CAPABILITY_INTERNET)
+                        .addCapability(NET_CAPABILITY_NOT_METERED)
+                        .addCapability(NET_CAPABILITY_NOT_ROAMING)
+                        .addCapability(NET_CAPABILITY_NOT_CONGESTED)
+                        .setLinkUpstreamBandwidthKbps(20));
         setMockedNetworks(networks);
 
         final NetworkCapabilities caps = new NetworkCapabilities();
 
-        Vpn.updateCapabilities(mConnectivityManager, new Network[] { }, caps);
+        Vpn.updateCapabilities(
+                mConnectivityManager, new Network[] {}, caps, false /* isAlwaysMetered */);
         assertTrue(caps.hasTransport(TRANSPORT_VPN));
         assertFalse(caps.hasTransport(TRANSPORT_CELLULAR));
         assertFalse(caps.hasTransport(TRANSPORT_WIFI));
@@ -570,17 +577,33 @@
         assertTrue(caps.hasCapability(NET_CAPABILITY_NOT_ROAMING));
         assertTrue(caps.hasCapability(NET_CAPABILITY_NOT_CONGESTED));
 
-        Vpn.updateCapabilities(mConnectivityManager, new Network[] { mobile }, caps);
+        Vpn.updateCapabilities(
+                mConnectivityManager,
+                new Network[] {mobile},
+                caps,
+                false /* isAlwaysMetered */);
         assertTrue(caps.hasTransport(TRANSPORT_VPN));
         assertTrue(caps.hasTransport(TRANSPORT_CELLULAR));
         assertFalse(caps.hasTransport(TRANSPORT_WIFI));
         assertEquals(10, caps.getLinkDownstreamBandwidthKbps());
         assertEquals(LINK_BANDWIDTH_UNSPECIFIED, caps.getLinkUpstreamBandwidthKbps());
-        assertTrue(caps.hasCapability(NET_CAPABILITY_NOT_METERED));
+        assertFalse(caps.hasCapability(NET_CAPABILITY_NOT_METERED));
         assertFalse(caps.hasCapability(NET_CAPABILITY_NOT_ROAMING));
         assertTrue(caps.hasCapability(NET_CAPABILITY_NOT_CONGESTED));
 
-        Vpn.updateCapabilities(mConnectivityManager, new Network[] { wifi }, caps);
+        Vpn.updateCapabilities(
+                mConnectivityManager, new Network[] {wifi}, caps, false /* isAlwaysMetered */);
+        assertTrue(caps.hasTransport(TRANSPORT_VPN));
+        assertFalse(caps.hasTransport(TRANSPORT_CELLULAR));
+        assertTrue(caps.hasTransport(TRANSPORT_WIFI));
+        assertEquals(LINK_BANDWIDTH_UNSPECIFIED, caps.getLinkDownstreamBandwidthKbps());
+        assertEquals(20, caps.getLinkUpstreamBandwidthKbps());
+        assertTrue(caps.hasCapability(NET_CAPABILITY_NOT_METERED));
+        assertTrue(caps.hasCapability(NET_CAPABILITY_NOT_ROAMING));
+        assertTrue(caps.hasCapability(NET_CAPABILITY_NOT_CONGESTED));
+
+        Vpn.updateCapabilities(
+                mConnectivityManager, new Network[] {wifi}, caps, true /* isAlwaysMetered */);
         assertTrue(caps.hasTransport(TRANSPORT_VPN));
         assertFalse(caps.hasTransport(TRANSPORT_CELLULAR));
         assertTrue(caps.hasTransport(TRANSPORT_WIFI));
@@ -590,7 +613,11 @@
         assertTrue(caps.hasCapability(NET_CAPABILITY_NOT_ROAMING));
         assertTrue(caps.hasCapability(NET_CAPABILITY_NOT_CONGESTED));
 
-        Vpn.updateCapabilities(mConnectivityManager, new Network[] { mobile, wifi }, caps);
+        Vpn.updateCapabilities(
+                mConnectivityManager,
+                new Network[] {mobile, wifi},
+                caps,
+                false /* isAlwaysMetered */);
         assertTrue(caps.hasTransport(TRANSPORT_VPN));
         assertTrue(caps.hasTransport(TRANSPORT_CELLULAR));
         assertTrue(caps.hasTransport(TRANSPORT_WIFI));