diff --git a/framework/api/current.txt b/framework/api/current.txt
index a8f1a4d..243e4ca 100644
--- a/framework/api/current.txt
+++ b/framework/api/current.txt
@@ -143,6 +143,7 @@
 
   public static class ConnectivityManager.NetworkCallback {
     ctor public ConnectivityManager.NetworkCallback();
+    ctor public ConnectivityManager.NetworkCallback(int);
     method public void onAvailable(@NonNull android.net.Network);
     method public void onBlockedStatusChanged(@NonNull android.net.Network, boolean);
     method public void onCapabilitiesChanged(@NonNull android.net.Network, @NonNull android.net.NetworkCapabilities);
@@ -150,6 +151,7 @@
     method public void onLosing(@NonNull android.net.Network, int);
     method public void onLost(@NonNull android.net.Network);
     method public void onUnavailable();
+    field public static final int FLAG_INCLUDE_LOCATION_INFO = 1; // 0x1
   }
 
   public static interface ConnectivityManager.OnNetworkActiveListener {
@@ -293,6 +295,7 @@
     method @Nullable public android.net.NetworkSpecifier getNetworkSpecifier();
     method public int getOwnerUid();
     method public int getSignalStrength();
+    method @NonNull public java.util.Set<java.lang.Integer> getSubIds();
     method @Nullable public android.net.TransportInfo getTransportInfo();
     method public boolean hasCapability(int);
     method public boolean hasTransport(int);
@@ -399,6 +402,11 @@
     method public android.net.NetworkRequest.Builder removeTransportType(int);
     method @Deprecated public android.net.NetworkRequest.Builder setNetworkSpecifier(String);
     method public android.net.NetworkRequest.Builder setNetworkSpecifier(android.net.NetworkSpecifier);
+    method @NonNull public android.net.NetworkRequest.Builder setSubIds(@NonNull java.util.Set<java.lang.Integer>);
+  }
+
+  public class ParseException extends java.lang.RuntimeException {
+    field public String response;
   }
 
   public class ProxyInfo implements android.os.Parcelable {
diff --git a/framework/api/module-lib-current.txt b/framework/api/module-lib-current.txt
index d2ed73e..4b33366 100644
--- a/framework/api/module-lib-current.txt
+++ b/framework/api/module-lib-current.txt
@@ -7,8 +7,9 @@
 
   public class ConnectivityManager {
     method @NonNull @RequiresPermission(anyOf={android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, android.Manifest.permission.NETWORK_STACK, android.Manifest.permission.NETWORK_SETTINGS}) public java.util.List<android.net.NetworkStateSnapshot> getAllNetworkStateSnapshot();
+    method @NonNull public static android.util.Range<java.lang.Integer> getIpSecNetIdRange();
     method @RequiresPermission(anyOf={android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, android.Manifest.permission.NETWORK_SETTINGS}) public void registerSystemDefaultNetworkCallback(@NonNull android.net.ConnectivityManager.NetworkCallback, @NonNull android.os.Handler);
-    method @RequiresPermission(anyOf={android.Manifest.permission.NETWORK_SETTINGS, android.Manifest.permission.NETWORK_STACK, android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK}) public void requestBackgroundNetwork(@NonNull android.net.NetworkRequest, @Nullable android.os.Handler, @NonNull android.net.ConnectivityManager.NetworkCallback);
+    method @RequiresPermission(anyOf={android.Manifest.permission.NETWORK_SETTINGS, android.Manifest.permission.NETWORK_STACK, android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK}) public void requestBackgroundNetwork(@NonNull android.net.NetworkRequest, @NonNull android.os.Handler, @NonNull android.net.ConnectivityManager.NetworkCallback);
     method @RequiresPermission(anyOf={android.Manifest.permission.MANAGE_TEST_NETWORKS, android.Manifest.permission.NETWORK_STACK}) public void simulateDataStall(int, long, @NonNull android.net.Network, @NonNull android.os.PersistableBundle);
   }
 
@@ -51,6 +52,14 @@
     field public static final String TEST_TAP_PREFIX = "testtap";
   }
 
+  public final class TestNetworkSpecifier extends android.net.NetworkSpecifier implements android.os.Parcelable {
+    ctor public TestNetworkSpecifier(@NonNull String);
+    method public int describeContents();
+    method @Nullable public String getInterfaceName();
+    method public void writeToParcel(@NonNull android.os.Parcel, int);
+    field @NonNull public static final android.os.Parcelable.Creator<android.net.TestNetworkSpecifier> CREATOR;
+  }
+
   public final class VpnTransportInfo implements android.os.Parcelable android.net.TransportInfo {
     ctor public VpnTransportInfo(int);
     method public int describeContents();
diff --git a/framework/api/system-current.txt b/framework/api/system-current.txt
index a732430..a98f14e 100644
--- a/framework/api/system-current.txt
+++ b/framework/api/system-current.txt
@@ -296,6 +296,7 @@
     method @NonNull @RequiresPermission(android.Manifest.permission.NETWORK_FACTORY) public android.net.NetworkCapabilities.Builder setRequestorUid(int);
     method @NonNull @RequiresPermission(android.Manifest.permission.NETWORK_SIGNAL_STRENGTH_WAKEUP) public android.net.NetworkCapabilities.Builder setSignalStrength(int);
     method @NonNull @RequiresPermission(android.Manifest.permission.NETWORK_FACTORY) public android.net.NetworkCapabilities.Builder setSsid(@Nullable String);
+    method @NonNull public android.net.NetworkCapabilities.Builder setSubIds(@NonNull java.util.Set<java.lang.Integer>);
     method @NonNull public android.net.NetworkCapabilities.Builder setTransportInfo(@Nullable android.net.TransportInfo);
   }
 
diff --git a/framework/src/android/net/ConnectivityManager.java b/framework/src/android/net/ConnectivityManager.java
index 77e67ba..8c66db9 100644
--- a/framework/src/android/net/ConnectivityManager.java
+++ b/framework/src/android/net/ConnectivityManager.java
@@ -19,6 +19,7 @@
 import static android.net.NetworkRequest.Type.BACKGROUND_REQUEST;
 import static android.net.NetworkRequest.Type.LISTEN;
 import static android.net.NetworkRequest.Type.REQUEST;
+import static android.net.NetworkRequest.Type.TRACK_BEST;
 import static android.net.NetworkRequest.Type.TRACK_DEFAULT;
 import static android.net.NetworkRequest.Type.TRACK_SYSTEM_DEFAULT;
 import static android.net.QosCallback.QosCallbackRegistrationException;
@@ -42,6 +43,7 @@
 import android.net.TetheringManager.StartTetheringCallback;
 import android.net.TetheringManager.TetheringEventCallback;
 import android.net.TetheringManager.TetheringRequest;
+import android.net.wifi.WifiNetworkSuggestion;
 import android.os.Binder;
 import android.os.Build;
 import android.os.Build.VERSION_CODES;
@@ -1313,7 +1315,7 @@
     }
 
     /**
-     * Returns an array of {@link android.net.NetworkCapabilities} objects, representing
+     * Returns an array of {@link NetworkCapabilities} objects, representing
      * the Networks that applications run by the given user will use by default.
      * @hide
      */
@@ -1393,11 +1395,19 @@
     }
 
     /**
-     * Get the {@link android.net.NetworkCapabilities} for the given {@link Network}.  This
+     * Get the {@link NetworkCapabilities} for the given {@link Network}.  This
      * will return {@code null} if the network is unknown.
      *
+     * This will remove any location sensitive data in {@link TransportInfo} embedded in
+     * {@link NetworkCapabilities#getTransportInfo()}. Some transport info instances like
+     * {@link android.net.wifi.WifiInfo} contain location sensitive information. Retrieving
+     * this location sensitive information (subject to app's location permissions) will be
+     * noted by system. To include any location sensitive data in {@link TransportInfo},
+     * use a {@link NetworkCallback} with
+     * {@link NetworkCallback#FLAG_INCLUDE_LOCATION_INFO} flag.
+     *
      * @param network The {@link Network} object identifying the network in question.
-     * @return The {@link android.net.NetworkCapabilities} for the network, or {@code null}.
+     * @return The {@link NetworkCapabilities} for the network, or {@code null}.
      */
     @RequiresPermission(android.Manifest.permission.ACCESS_NETWORK_STATE)
     @Nullable
@@ -3243,6 +3253,54 @@
      */
     public static class NetworkCallback {
         /**
+         * No flags associated with this callback.
+         * @hide
+         */
+        public static final int FLAG_NONE = 0;
+        /**
+         * Use this flag to include any location sensitive data in {@link NetworkCapabilities} sent
+         * via {@link #onCapabilitiesChanged(Network, NetworkCapabilities)}.
+         * <p>
+         * These include:
+         * <li> Some transport info instances (retrieved via
+         * {@link NetworkCapabilities#getTransportInfo()}) like {@link android.net.wifi.WifiInfo}
+         * contain location sensitive information.
+         * <li> OwnerUid (retrieved via {@link NetworkCapabilities#getOwnerUid()} is location
+         * sensitive for wifi suggestor apps (i.e using {@link WifiNetworkSuggestion}).</li>
+         * </p>
+         * <p>
+         * Note:
+         * <li> Retrieving this location sensitive information (subject to app's location
+         * permissions) will be noted by system. </li>
+         * <li> Without this flag any {@link NetworkCapabilities} provided via the callback does
+         * not include location sensitive info.
+         * </p>
+         */
+        public static final int FLAG_INCLUDE_LOCATION_INFO = 1 << 0;
+
+        /** @hide */
+        @Retention(RetentionPolicy.SOURCE)
+        @IntDef(flag = true, prefix = "FLAG_", value = {
+                FLAG_NONE,
+                FLAG_INCLUDE_LOCATION_INFO
+        })
+        public @interface Flag { }
+
+        /**
+         * All the valid flags for error checking.
+         */
+        private static final int VALID_FLAGS = FLAG_INCLUDE_LOCATION_INFO;
+
+        public NetworkCallback() {
+            this(FLAG_NONE);
+        }
+
+        public NetworkCallback(@Flag int flags) {
+            Preconditions.checkArgument((flags & VALID_FLAGS) == flags);
+            mFlags = flags;
+        }
+
+        /**
          * Called when the framework connects to a new network to evaluate whether it satisfies this
          * request. If evaluation succeeds, this callback may be followed by an {@link #onAvailable}
          * callback. There is no guarantee that this new network will satisfy any requests, or that
@@ -3379,7 +3437,7 @@
          * calling these methods while in a callback may return an outdated or even a null object.
          *
          * @param network The {@link Network} whose capabilities have changed.
-         * @param networkCapabilities The new {@link android.net.NetworkCapabilities} for this
+         * @param networkCapabilities The new {@link NetworkCapabilities} for this
          *                            network.
          */
         public void onCapabilitiesChanged(@NonNull Network network,
@@ -3448,6 +3506,7 @@
         public void onBlockedStatusChanged(@NonNull Network network, boolean blocked) {}
 
         private NetworkRequest networkRequest;
+        private final int mFlags;
     }
 
     /**
@@ -3637,14 +3696,15 @@
                 }
                 Messenger messenger = new Messenger(handler);
                 Binder binder = new Binder();
+                final int callbackFlags = callback.mFlags;
                 if (reqType == LISTEN) {
                     request = mService.listenForNetwork(
-                            need, messenger, binder, callingPackageName,
+                            need, messenger, binder, callbackFlags, callingPackageName,
                             getAttributionTag());
                 } else {
                     request = mService.requestNetwork(
                             need, reqType.ordinal(), messenger, timeoutMs, binder, legacyType,
-                            callingPackageName, getAttributionTag());
+                            callbackFlags, callingPackageName, getAttributionTag());
                 }
                 if (request != null) {
                     sCallbacks.put(request, callback);
@@ -3691,7 +3751,7 @@
     }
 
     /**
-     * Request a network to satisfy a set of {@link android.net.NetworkCapabilities}.
+     * Request a network to satisfy a set of {@link NetworkCapabilities}.
      *
      * <p>This method will attempt to find the best network that matches the passed
      * {@link NetworkRequest}, and to bring up one that does if none currently satisfies the
@@ -3775,7 +3835,7 @@
     }
 
     /**
-     * Request a network to satisfy a set of {@link android.net.NetworkCapabilities}.
+     * Request a network to satisfy a set of {@link NetworkCapabilities}.
      *
      * This method behaves identically to {@link #requestNetwork(NetworkRequest, NetworkCallback)}
      * but runs all the callbacks on the passed Handler.
@@ -3797,7 +3857,7 @@
     }
 
     /**
-     * Request a network to satisfy a set of {@link android.net.NetworkCapabilities}, limited
+     * Request a network to satisfy a set of {@link NetworkCapabilities}, limited
      * by a timeout.
      *
      * This function behaves identically to the non-timed-out version
@@ -3832,7 +3892,7 @@
     }
 
     /**
-     * Request a network to satisfy a set of {@link android.net.NetworkCapabilities}, limited
+     * Request a network to satisfy a set of {@link NetworkCapabilities}, limited
      * by a timeout.
      *
      * This method behaves identically to
@@ -3877,7 +3937,7 @@
 
 
     /**
-     * Request a network to satisfy a set of {@link android.net.NetworkCapabilities}.
+     * Request a network to satisfy a set of {@link NetworkCapabilities}.
      *
      * This function behaves identically to the version that takes a NetworkCallback, but instead
      * of {@link NetworkCallback} a {@link PendingIntent} is used.  This means
@@ -4189,6 +4249,18 @@
     }
 
     /**
+     * @hide
+     */
+    // TODO: Make it public api.
+    @SuppressLint("ExecutorRegistration")
+    public void registerBestMatchingNetworkCallback(@NonNull NetworkRequest request,
+            @NonNull NetworkCallback networkCallback, @NonNull Handler handler) {
+        final NetworkCapabilities nc = request.networkCapabilities;
+        final CallbackHandler cbHandler = new CallbackHandler(handler);
+        sendRequestForNetwork(nc, networkCallback, 0, TRACK_BEST, TYPE_NONE, cbHandler);
+    }
+
+    /**
      * Requests bandwidth update for a given {@link Network} and returns whether the update request
      * is accepted by ConnectivityService. Once accepted, ConnectivityService will poll underlying
      * network connection for updated bandwidth information. The caller will be notified via
@@ -4897,7 +4969,7 @@
     }
 
     /**
-     * Request a network to satisfy a set of {@link android.net.NetworkCapabilities}, but
+     * Request a network to satisfy a set of {@link NetworkCapabilities}, but
      * does not cause any networks to retain the NET_CAPABILITY_FOREGROUND capability. This can
      * be used to request that the system provide a network without causing the network to be
      * in the foreground.
@@ -4978,10 +5050,10 @@
             NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK
     })
     public void requestBackgroundNetwork(@NonNull NetworkRequest request,
-            @Nullable Handler handler, @NonNull NetworkCallback networkCallback) {
+            @NonNull Handler handler, @NonNull NetworkCallback networkCallback) {
         final NetworkCapabilities nc = request.networkCapabilities;
         sendRequestForNetwork(nc, networkCallback, 0, BACKGROUND_REQUEST,
-                TYPE_NONE, handler == null ? getDefaultHandler() : new CallbackHandler(handler));
+                TYPE_NONE, new CallbackHandler(handler));
     }
 
     /**
@@ -5039,4 +5111,21 @@
             throw e.rethrowFromSystemServer();
         }
     }
+
+    // The first network ID of IPSec tunnel interface.
+    private static final int TUN_INTF_NETID_START = 0xFC00;
+    // The network ID range of IPSec tunnel interface.
+    private static final int TUN_INTF_NETID_RANGE = 0x0400;
+
+    /**
+     * Get the network ID range reserved for IPSec tunnel interfaces.
+     *
+     * @return A Range which indicates the network ID range of IPSec tunnel interface.
+     * @hide
+     */
+    @SystemApi(client = MODULE_LIBRARIES)
+    @NonNull
+    public static Range<Integer> getIpSecNetIdRange() {
+        return new Range(TUN_INTF_NETID_START, TUN_INTF_NETID_START + TUN_INTF_NETID_RANGE - 1);
+    }
 }
diff --git a/framework/src/android/net/IConnectivityManager.aidl b/framework/src/android/net/IConnectivityManager.aidl
index cd49258..f9393e3 100644
--- a/framework/src/android/net/IConnectivityManager.aidl
+++ b/framework/src/android/net/IConnectivityManager.aidl
@@ -143,7 +143,7 @@
 
     NetworkRequest requestNetwork(in NetworkCapabilities networkCapabilities, int reqType,
             in Messenger messenger, int timeoutSec, in IBinder binder, int legacy,
-            String callingPackageName, String callingAttributionTag);
+            int callbackFlags, String callingPackageName, String callingAttributionTag);
 
     NetworkRequest pendingRequestForNetwork(in NetworkCapabilities networkCapabilities,
             in PendingIntent operation, String callingPackageName, String callingAttributionTag);
@@ -151,7 +151,7 @@
     void releasePendingNetworkRequest(in PendingIntent operation);
 
     NetworkRequest listenForNetwork(in NetworkCapabilities networkCapabilities,
-            in Messenger messenger, in IBinder binder, String callingPackageName,
+            in Messenger messenger, in IBinder binder, int callbackFlags, String callingPackageName,
             String callingAttributionTag);
 
     void pendingListenForNetwork(in NetworkCapabilities networkCapabilities,
diff --git a/framework/src/android/net/NetworkCapabilities.java b/framework/src/android/net/NetworkCapabilities.java
index c82cd3b..058f3c9 100644
--- a/framework/src/android/net/NetworkCapabilities.java
+++ b/framework/src/android/net/NetworkCapabilities.java
@@ -25,6 +25,7 @@
 import android.annotation.SystemApi;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.net.ConnectivityManager.NetworkCallback;
+import android.net.wifi.WifiNetworkSuggestion;
 import android.os.Build;
 import android.os.Parcel;
 import android.os.Parcelable;
@@ -131,6 +132,7 @@
         mPrivateDnsBroken = false;
         mRequestorUid = Process.INVALID_UID;
         mRequestorPackageName = null;
+        mSubIds = new ArraySet<>();
     }
 
     /**
@@ -159,6 +161,7 @@
         mPrivateDnsBroken = nc.mPrivateDnsBroken;
         mRequestorUid = nc.mRequestorUid;
         mRequestorPackageName = nc.mRequestorPackageName;
+        mSubIds = new ArraySet<>(nc.mSubIds);
     }
 
     /**
@@ -1048,6 +1051,16 @@
      *
      * Instances of NetworkCapabilities sent to apps without the appropriate permissions will have
      * this field cleared out.
+     *
+     * <p>
+     * This field will only be populated for VPN and wifi network suggestor apps (i.e using
+     * {@link WifiNetworkSuggestion}), and only for the network they own.
+     * In the case of wifi network suggestors apps, this field is also location sensitive, so the
+     * app needs to hold {@link android.Manifest.permission#ACCESS_FINE_LOCATION} permission. If the
+     * app targets SDK version greater than or equal to {@link Build.VERSION_CODES#S}, then they
+     * also need to use {@link NetworkCallback#FLAG_INCLUDE_LOCATION_INFO} to get the info in their
+     * callback. The app will be blamed for location access if this field is included.
+     * </p>
      */
     public int getOwnerUid() {
         return mOwnerUid;
@@ -1655,6 +1668,7 @@
         combineSSIDs(nc);
         combineRequestor(nc);
         combineAdministratorUids(nc);
+        combineSubIds(nc);
     }
 
     /**
@@ -1674,8 +1688,9 @@
                 && satisfiedBySpecifier(nc)
                 && (onlyImmutable || satisfiedBySignalStrength(nc))
                 && (onlyImmutable || satisfiedByUids(nc))
-                && (onlyImmutable || satisfiedBySSID(nc)))
-                && (onlyImmutable || satisfiedByRequestor(nc));
+                && (onlyImmutable || satisfiedBySSID(nc))
+                && (onlyImmutable || satisfiedByRequestor(nc))
+                && (onlyImmutable || satisfiedBySubIds(nc)));
     }
 
     /**
@@ -1771,7 +1786,8 @@
                 && equalsOwnerUid(that)
                 && equalsPrivateDnsBroken(that)
                 && equalsRequestor(that)
-                && equalsAdministratorUids(that);
+                && equalsAdministratorUids(that)
+                && equalsSubIds(that);
     }
 
     @Override
@@ -1793,7 +1809,8 @@
                 + Objects.hashCode(mPrivateDnsBroken) * 47
                 + Objects.hashCode(mRequestorUid) * 53
                 + Objects.hashCode(mRequestorPackageName) * 59
-                + Arrays.hashCode(mAdministratorUids) * 61;
+                + Arrays.hashCode(mAdministratorUids) * 61
+                + Objects.hashCode(mSubIds) * 67;
     }
 
     @Override
@@ -1827,6 +1844,7 @@
         dest.writeInt(mOwnerUid);
         dest.writeInt(mRequestorUid);
         dest.writeString(mRequestorPackageName);
+        dest.writeIntArray(CollectionUtils.toIntArray(mSubIds));
     }
 
     public static final @android.annotation.NonNull Creator<NetworkCapabilities> CREATOR =
@@ -1850,6 +1868,11 @@
                 netCap.mOwnerUid = in.readInt();
                 netCap.mRequestorUid = in.readInt();
                 netCap.mRequestorPackageName = in.readString();
+                netCap.mSubIds = new ArraySet<>();
+                final int[] subIdInts = Objects.requireNonNull(in.createIntArray());
+                for (int i = 0; i < subIdInts.length; i++) {
+                    netCap.mSubIds.add(subIdInts[i]);
+                }
                 return netCap;
             }
             @Override
@@ -1933,11 +1956,14 @@
             sb.append(" SSID: ").append(mSSID);
         }
 
-
         if (mPrivateDnsBroken) {
             sb.append(" PrivateDnsBroken");
         }
 
+        if (!mSubIds.isEmpty()) {
+            sb.append(" SubscriptionIds: ").append(mSubIds);
+        }
+
         sb.append("]");
         return sb.toString();
     }
@@ -2251,6 +2277,67 @@
     }
 
     /**
+     * Set of the subscription IDs that identifies the network or request, empty if none.
+     */
+    @NonNull
+    private ArraySet<Integer> mSubIds = new ArraySet<>();
+
+    /**
+     * Sets the subscription ID set that associated to this network or request.
+     *
+     * @hide
+     */
+    @NonNull
+    public NetworkCapabilities setSubIds(@NonNull Set<Integer> subIds) {
+        mSubIds = new ArraySet(Objects.requireNonNull(subIds));
+        return this;
+    }
+
+    /**
+     * Gets the subscription ID set that associated to this network or request.
+     * @return
+     */
+    @NonNull
+    public Set<Integer> getSubIds() {
+        return new ArraySet<>(mSubIds);
+    }
+
+    /**
+     * Tests if the subscription ID set of this network is the same as that of the passed one.
+     */
+    private boolean equalsSubIds(@NonNull NetworkCapabilities nc) {
+        return Objects.equals(mSubIds, nc.mSubIds);
+    }
+
+    /**
+     * Check if the subscription ID set requirements of this object are matched by the passed one.
+     * If specified in the request, the passed one need to have at least one subId and at least
+     * one of them needs to be in the request set.
+     */
+    private boolean satisfiedBySubIds(@NonNull NetworkCapabilities nc) {
+        if (mSubIds.isEmpty()) return true;
+        if (nc.mSubIds.isEmpty()) return false;
+        for (final Integer subId : nc.mSubIds) {
+            if (mSubIds.contains(subId)) return true;
+        }
+        return false;
+    }
+
+    /**
+     * Combine subscription ID set of the capabilities.
+     *
+     * <p>This is only legal if the subscription Ids are equal.
+     *
+     * <p>If both subscription IDs are not equal, they belong to different subscription
+     * (or no subscription). In this case, it would not make sense to add them together.
+     */
+    private void combineSubIds(@NonNull NetworkCapabilities nc) {
+        if (!Objects.equals(mSubIds, nc.mSubIds)) {
+            throw new IllegalStateException("Can't combine two subscription ID sets");
+        }
+    }
+
+    /**
      * Builder class for NetworkCapabilities.
      *
      * This class is mainly for for {@link NetworkAgent} instances to use. Many fields in
@@ -2556,6 +2643,18 @@
         }
 
         /**
+         * Set the subscription ID set.
+         *
+         * @param subIds a set that represent the subscription IDs. Empty if clean up.
+         * @return this builder.
+         */
+        @NonNull
+        public Builder setSubIds(@NonNull final Set<Integer> subIds) {
+            mCaps.setSubIds(subIds);
+            return this;
+        }
+
+        /**
          * Builds the instance of the capabilities.
          *
          * @return the built instance of NetworkCapabilities.
diff --git a/framework/src/android/net/NetworkRequest.java b/framework/src/android/net/NetworkRequest.java
index b4a651c..3fd95ee 100644
--- a/framework/src/android/net/NetworkRequest.java
+++ b/framework/src/android/net/NetworkRequest.java
@@ -31,6 +31,7 @@
 import static android.net.NetworkCapabilities.NET_CAPABILITY_TEMPORARILY_NOT_METERED;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_TRUSTED;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED;
+import static android.net.NetworkCapabilities.TRANSPORT_TEST;
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
@@ -113,6 +114,10 @@
      *       for the network (if any) that satisfies the default Internet
      *       request.
      *
+     *     - TRACK_BEST, which causes the framework to send callbacks about
+     *       the single, highest scoring current network (if any) that matches
+     *       the specified NetworkCapabilities.
+     *
      *     - BACKGROUND_REQUEST, like REQUEST but does not cause any networks
      *       to retain the NET_CAPABILITY_FOREGROUND capability. A network with
      *       no foreground requests is in the background. A network that has
@@ -135,6 +140,7 @@
         REQUEST,
         BACKGROUND_REQUEST,
         TRACK_SYSTEM_DEFAULT,
+        TRACK_BEST,
     };
 
     /**
@@ -382,11 +388,17 @@
                 return setNetworkSpecifier(new TelephonyNetworkSpecifier.Builder()
                         .setSubscriptionId(subId).build());
             } catch (NumberFormatException nfe) {
-                // A StringNetworkSpecifier does not accept null or empty ("") strings. When network
-                // specifiers were strings a null string and an empty string were considered
-                // equivalent. Hence no meaning is attached to a null or empty ("") string.
-                return setNetworkSpecifier(TextUtils.isEmpty(networkSpecifier) ? null
-                        : new StringNetworkSpecifier(networkSpecifier));
+                // An EthernetNetworkSpecifier or TestNetworkSpecifier does not accept null or empty
+                // ("") strings. When network specifiers were strings a null string and an empty
+                // string were considered equivalent. Hence no meaning is attached to a null or
+                // empty ("") string.
+                if (TextUtils.isEmpty(networkSpecifier)) {
+                    return setNetworkSpecifier((NetworkSpecifier) null);
+                } else if (mNetworkCapabilities.hasTransport(TRANSPORT_TEST)) {
+                    return setNetworkSpecifier(new TestNetworkSpecifier(networkSpecifier));
+                } else {
+                    return setNetworkSpecifier(new EthernetNetworkSpecifier(networkSpecifier));
+                }
             }
         }
 
@@ -449,6 +461,21 @@
             }
             nc.addCapability(NET_CAPABILITY_NOT_VCN_MANAGED);
         }
+
+        /**
+         * Sets the optional subscription ID set.
+         * <p>
+         * This specify the subscription IDs requirement.
+         * A network will satisfy this request only if it matches one of the subIds in this set.
+         * An empty set matches all networks, including those without a subId.
+         *
+         * @param subIds A {@code Set} that represents subscription IDs.
+         */
+        @NonNull
+        public Builder setSubIds(@NonNull Set<Integer> subIds) {
+            mNetworkCapabilities.setSubIds(subIds);
+            return this;
+        }
     }
 
     // implement the Parcelable interface
diff --git a/framework/src/android/net/NetworkState.java b/framework/src/android/net/NetworkState.java
index d010265..9b69674 100644
--- a/framework/src/android/net/NetworkState.java
+++ b/framework/src/android/net/NetworkState.java
@@ -22,7 +22,7 @@
 import android.os.Build;
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.util.Slog;
+import android.util.Log;
 
 /**
  * Snapshot of network state.
@@ -83,7 +83,7 @@
         if (VALIDATE_ROAMING_STATE && networkInfo != null && networkCapabilities != null) {
             if (networkInfo.isRoaming() == networkCapabilities
                     .hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_ROAMING)) {
-                Slog.wtf("NetworkState", "Roaming state disagreement between " + networkInfo
+                Log.wtf("NetworkState", "Roaming state disagreement between " + networkInfo
                         + " and " + networkCapabilities);
             }
         }
diff --git a/framework/src/android/net/ParseException.java b/framework/src/android/net/ParseException.java
new file mode 100644
index 0000000..bcfdd7e
--- /dev/null
+++ b/framework/src/android/net/ParseException.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2006 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;
+
+/**
+ * Thrown when parsing failed.
+ */
+// See non-public class {@link WebAddress}.
+public class ParseException extends RuntimeException {
+    public String response;
+
+    ParseException(@NonNull String response) {
+        super(response);
+        this.response = response;
+    }
+
+    ParseException(@NonNull String response, @NonNull Throwable cause) {
+        super(response, cause);
+        this.response = response;
+    }
+}
diff --git a/framework/src/android/net/QosSocketInfo.java b/framework/src/android/net/QosSocketInfo.java
index d37c469..3bf700b 100644
--- a/framework/src/android/net/QosSocketInfo.java
+++ b/framework/src/android/net/QosSocketInfo.java
@@ -92,7 +92,7 @@
         Objects.requireNonNull(socket, "socket cannot be null");
 
         mNetwork = Objects.requireNonNull(network, "network cannot be null");
-        mParcelFileDescriptor = ParcelFileDescriptor.dup(socket.getFileDescriptor$());
+        mParcelFileDescriptor = ParcelFileDescriptor.fromSocket(socket);
         mLocalSocketAddress =
                 new InetSocketAddress(socket.getLocalAddress(), socket.getLocalPort());
     }
diff --git a/framework/src/android/net/TestNetworkSpecifier.java b/framework/src/android/net/TestNetworkSpecifier.java
new file mode 100644
index 0000000..b7470a5
--- /dev/null
+++ b/framework/src/android/net/TestNetworkSpecifier.java
@@ -0,0 +1,97 @@
+/*
+ * 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;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.SystemApi;
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.text.TextUtils;
+
+import com.android.internal.util.Preconditions;
+
+import java.util.Objects;
+
+/**
+ * A {@link NetworkSpecifier} used to identify test interfaces.
+ *
+ * @see TestNetworkManager
+ * @hide
+ */
+@SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
+public final class TestNetworkSpecifier extends NetworkSpecifier implements Parcelable {
+
+    /**
+     * Name of the network interface.
+     */
+    @NonNull
+    private final String mInterfaceName;
+
+    public TestNetworkSpecifier(@NonNull String interfaceName) {
+        Preconditions.checkStringNotEmpty(interfaceName);
+        mInterfaceName = interfaceName;
+    }
+
+    // This may be null in the future to support specifiers based on data other than the interface
+    // name.
+    @Nullable
+    public String getInterfaceName() {
+        return mInterfaceName;
+    }
+
+    @Override
+    public boolean canBeSatisfiedBy(@Nullable NetworkSpecifier other) {
+        return equals(other);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (!(o instanceof TestNetworkSpecifier)) return false;
+        return TextUtils.equals(mInterfaceName, ((TestNetworkSpecifier) o).mInterfaceName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(mInterfaceName);
+    }
+
+    @Override
+    public String toString() {
+        return "TestNetworkSpecifier (" + mInterfaceName + ")";
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(@NonNull Parcel dest, int flags) {
+        dest.writeString(mInterfaceName);
+    }
+
+    public static final @NonNull Creator<TestNetworkSpecifier> CREATOR =
+            new Creator<TestNetworkSpecifier>() {
+        public TestNetworkSpecifier createFromParcel(Parcel in) {
+            return new TestNetworkSpecifier(in.readString());
+        }
+        public TestNetworkSpecifier[] newArray(int size) {
+            return new TestNetworkSpecifier[size];
+        }
+    };
+}