Fix NOT_RESTRICTED network capability and enforce it.

With this change:
1. NOT_RESTRICTED should be removed from NetworkRequests that bring up
   special restricted carrier networks (e.g. IMS, FOTA).
2. NetworkRequests without NOT_RESTRICTED require CONNECTIVITY_INTERNAL
   permission to register
3. Binding sockets to networks without NOT_RESTRICTED requires
   CONNECTIVITY_INTERNAL permission

Bug:21637535
Change-Id: I5991d39facaa6b690e969fe15dcbeec52e918321

3 files changed, 48 insertions, 42 deletions

diff --git a/core/java/android/net/ConnectivityManager.java b/core/java/android/net/ConnectivityManager.java
index dc8ff8f..4d45076 100644
--- a/core/java/android/net/ConnectivityManager.java
+++ b/core/java/android/net/ConnectivityManager.java
@@ -956,41 +956,6 @@ public class ConnectivityManager {
         return 1;
     }
 
-    /**
-     * Removes the NET_CAPABILITY_NOT_RESTRICTED capability from the given
-     * NetworkCapabilities object if all the capabilities it provides are
-     * typically provided by restricted networks.
-     *
-     * TODO: consider:
-     * - Moving to NetworkCapabilities
-     * - Renaming it to guessRestrictedCapability and make it set the
-     *   restricted capability bit in addition to clearing it.
-     * @hide
-     */
-    public static void maybeMarkCapabilitiesRestricted(NetworkCapabilities nc) {
-        for (int capability : nc.getCapabilities()) {
-            switch (capability) {
-                case NetworkCapabilities.NET_CAPABILITY_CBS:
-                case NetworkCapabilities.NET_CAPABILITY_DUN:
-                case NetworkCapabilities.NET_CAPABILITY_EIMS:
-                case NetworkCapabilities.NET_CAPABILITY_FOTA:
-                case NetworkCapabilities.NET_CAPABILITY_IA:
-                case NetworkCapabilities.NET_CAPABILITY_IMS:
-                case NetworkCapabilities.NET_CAPABILITY_RCS:
-                case NetworkCapabilities.NET_CAPABILITY_XCAP:
-                case NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED: //there by default
-                    continue;
-                default:
-                    // At least one capability usually provided by unrestricted
-                    // networks. Conclude that this network is unrestricted.
-                    return;
-            }
-        }
-        // All the capabilities are typically provided by restricted networks.
-        // Conclude that this network is restricted.
-        nc.removeCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED);
-    }
-
     private NetworkCapabilities networkCapabilitiesForFeature(int networkType, String feature) {
         if (networkType == TYPE_MOBILE) {
             int cap = -1;
@@ -1013,14 +978,14 @@ public class ConnectivityManager {
             }
             NetworkCapabilities netCap = new NetworkCapabilities();
             netCap.addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR).addCapability(cap);
-            maybeMarkCapabilitiesRestricted(netCap);
+            netCap.maybeMarkCapabilitiesRestricted();
             return netCap;
         } else if (networkType == TYPE_WIFI) {
             if ("p2p".equals(feature)) {
                 NetworkCapabilities netCap = new NetworkCapabilities();
                 netCap.addTransportType(NetworkCapabilities.TRANSPORT_WIFI);
                 netCap.addCapability(NetworkCapabilities.NET_CAPABILITY_WIFI_P2P);
-                maybeMarkCapabilitiesRestricted(netCap);
+                netCap.maybeMarkCapabilitiesRestricted();
                 return netCap;
             }
         }
diff --git a/core/java/android/net/NetworkCapabilities.java b/core/java/android/net/NetworkCapabilities.java
index 514d24a..0154eb5 100644
--- a/core/java/android/net/NetworkCapabilities.java
+++ b/core/java/android/net/NetworkCapabilities.java
@@ -38,10 +38,7 @@ public final class NetworkCapabilities implements Parcelable {
      */
     public NetworkCapabilities() {
         clearAll();
-        mNetworkCapabilities =
-                (1 << NET_CAPABILITY_NOT_RESTRICTED) |
-                (1 << NET_CAPABILITY_TRUSTED) |
-                (1 << NET_CAPABILITY_NOT_VPN);
+        mNetworkCapabilities = DEFAULT_CAPABILITIES;
     }
 
     public NetworkCapabilities(NetworkCapabilities nc) {
@@ -187,6 +184,28 @@ public final class NetworkCapabilities implements Parcelable {
     private static final int MAX_NET_CAPABILITY = NET_CAPABILITY_CAPTIVE_PORTAL;
 
     /**
+     * Capabilities that are set by default when the object is constructed.
+     */
+    private static final long DEFAULT_CAPABILITIES =
+            (1 << NET_CAPABILITY_NOT_RESTRICTED) |
+            (1 << NET_CAPABILITY_TRUSTED) |
+            (1 << NET_CAPABILITY_NOT_VPN);
+
+    /**
+     * Capabilities that suggest that a network is restricted.
+     * {@see #maybeMarkCapabilitiesRestricted}.
+     */
+    private static final long RESTRICTED_CAPABILITIES =
+            (1 << NET_CAPABILITY_CBS) |
+            (1 << NET_CAPABILITY_DUN) |
+            (1 << NET_CAPABILITY_EIMS) |
+            (1 << NET_CAPABILITY_FOTA) |
+            (1 << NET_CAPABILITY_IA) |
+            (1 << NET_CAPABILITY_IMS) |
+            (1 << NET_CAPABILITY_RCS) |
+            (1 << NET_CAPABILITY_XCAP);
+
+    /**
      * Adds the given capability to this {@code NetworkCapability} instance.
      * Multiple capabilities may be applied sequentially.  Note that when searching
      * for a network to satisfy a request, all capabilities requested must be satisfied.
@@ -269,6 +288,22 @@ public final class NetworkCapabilities implements Parcelable {
     }
 
     /**
+     * Removes the NET_CAPABILITY_NOT_RESTRICTED capability if all the capabilities it provides are
+     * typically provided by restricted networks.
+     *
+     * TODO: consider:
+     * - Renaming it to guessRestrictedCapability and make it set the
+     *   restricted capability bit in addition to clearing it.
+     * @hide
+     */
+    public void maybeMarkCapabilitiesRestricted() {
+        // If all the capabilities are typically provided by restricted networks, conclude that this
+        // network is restricted.
+        if ((mNetworkCapabilities & ~(DEFAULT_CAPABILITIES | RESTRICTED_CAPABILITIES)) == 0)
+            removeCapability(NET_CAPABILITY_NOT_RESTRICTED);
+    }
+
+    /**
      * Representing the transport type.  Apps should generally not care about transport.  A
      * request for a fast internet connection could be satisfied by a number of different
      * transports.  If any are specified here it will be satisfied a Network that matches
diff --git a/core/java/android/net/NetworkRequest.java b/core/java/android/net/NetworkRequest.java
index e61594c..e184ec4 100644
--- a/core/java/android/net/NetworkRequest.java
+++ b/core/java/android/net/NetworkRequest.java
@@ -83,7 +83,13 @@ public class NetworkRequest implements Parcelable {
          * Build {@link NetworkRequest} give the current set of capabilities.
          */
         public NetworkRequest build() {
-            return new NetworkRequest(mNetworkCapabilities, ConnectivityManager.TYPE_NONE,
+            // Make a copy of mNetworkCapabilities so we don't inadvertently remove NOT_RESTRICTED
+            // when later an unrestricted capability could be added to mNetworkCapabilities, in
+            // which case NOT_RESTRICTED should be returned to mNetworkCapabilities, which
+            // maybeMarkCapabilitiesRestricted() doesn't add back.
+            final NetworkCapabilities nc = new NetworkCapabilities(mNetworkCapabilities);
+            nc.maybeMarkCapabilitiesRestricted();
+            return new NetworkRequest(nc, ConnectivityManager.TYPE_NONE,
                     ConnectivityManager.REQUEST_ID_UNSET);
         }