Update VPN capabilities when its underlying network set is null.

Previously, they were only updated when underlying network set was
non-null.

This change also ensures that all the calls b/w ConnectivityService and
Vpn that leads to updating capabilities are on ConnectivityService
handler thread.

Additionally, it also ensures that capabilities are propagated after VPN
enters connected state. This was previously done from establish which
could potentially lead to race between VPN getting connected and
capabilities getting updated.

This change also updates VPN capabilities inline from
ConnectivityService handler thread. Previously, there was an additional
loop where Vpn would update capabilities via NetworkAgent thru
AsyncChannel which posts back to CS handler thread, which could
potentially lead to delays in updating VPN capabilities.

Bug: 119129310
Bug: 118856062
Bug: 124268198
Test: atest FrameworksNetTests
Test: manual - verified VPNs capabilities are getting updated and
DownloadManager is working correctly.

Change-Id: Id0abc4d304bb096e92479a118168690ccce634ed
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index f2d4ae2..95f2a1f 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -917,7 +917,8 @@
 
         mPermissionMonitor = new PermissionMonitor(mContext, mNMS);
 
-        //set up the listener for user state for creating user VPNs
+        // Set up the listener for user state for creating user VPNs.
+        // Should run on mHandler to avoid any races.
         IntentFilter intentFilter = new IntentFilter();
         intentFilter.addAction(Intent.ACTION_USER_STARTED);
         intentFilter.addAction(Intent.ACTION_USER_STOPPED);
@@ -925,7 +926,11 @@
         intentFilter.addAction(Intent.ACTION_USER_REMOVED);
         intentFilter.addAction(Intent.ACTION_USER_UNLOCKED);
         mContext.registerReceiverAsUser(
-                mIntentReceiver, UserHandle.ALL, intentFilter, null, null);
+                mIntentReceiver,
+                UserHandle.ALL,
+                intentFilter,
+                null /* broadcastPermission */,
+                mHandler);
         mContext.registerReceiverAsUser(mUserPresentReceiver, UserHandle.SYSTEM,
                 new IntentFilter(Intent.ACTION_USER_PRESENT), null, null);
 
@@ -936,7 +941,11 @@
         intentFilter.addAction(Intent.ACTION_PACKAGE_REMOVED);
         intentFilter.addDataScheme("package");
         mContext.registerReceiverAsUser(
-                mIntentReceiver, UserHandle.ALL, intentFilter, null, null);
+                mIntentReceiver,
+                UserHandle.ALL,
+                intentFilter,
+                null /* broadcastPermission */,
+                mHandler);
 
         try {
             mNMS.registerObserver(mTethering);
@@ -4088,17 +4097,27 @@
      * handler thread through their agent, this is asynchronous. When the capabilities objects
      * are computed they will be up-to-date as they are computed synchronously from here and
      * this is running on the ConnectivityService thread.
-     * TODO : Fix this and call updateCapabilities inline to remove out-of-order events.
      */
     private void updateAllVpnsCapabilities() {
+        Network defaultNetwork = getNetwork(getDefaultNetwork());
         synchronized (mVpns) {
             for (int i = 0; i < mVpns.size(); i++) {
                 final Vpn vpn = mVpns.valueAt(i);
-                vpn.updateCapabilities();
+                NetworkCapabilities nc = vpn.updateCapabilities(defaultNetwork);
+                updateVpnCapabilities(vpn, nc);
             }
         }
     }
 
+    private void updateVpnCapabilities(Vpn vpn, @Nullable NetworkCapabilities nc) {
+        ensureRunningOnConnectivityServiceThread();
+        NetworkAgentInfo vpnNai = getNetworkAgentInfoForNetId(vpn.getNetId());
+        if (vpnNai == null || nc == null) {
+            return;
+        }
+        updateCapabilities(vpnNai.getCurrentScore(), vpnNai, nc);
+    }
+
     @Override
     public boolean updateLockdownVpn() {
         if (Binder.getCallingUid() != Process.SYSTEM_UID) {
@@ -4439,22 +4458,28 @@
 
     private void onUserAdded(int userId) {
         mPermissionMonitor.onUserAdded(userId);
+        Network defaultNetwork = getNetwork(getDefaultNetwork());
         synchronized (mVpns) {
             final int vpnsSize = mVpns.size();
             for (int i = 0; i < vpnsSize; i++) {
                 Vpn vpn = mVpns.valueAt(i);
                 vpn.onUserAdded(userId);
+                NetworkCapabilities nc = vpn.updateCapabilities(defaultNetwork);
+                updateVpnCapabilities(vpn, nc);
             }
         }
     }
 
     private void onUserRemoved(int userId) {
         mPermissionMonitor.onUserRemoved(userId);
+        Network defaultNetwork = getNetwork(getDefaultNetwork());
         synchronized (mVpns) {
             final int vpnsSize = mVpns.size();
             for (int i = 0; i < vpnsSize; i++) {
                 Vpn vpn = mVpns.valueAt(i);
                 vpn.onUserRemoved(userId);
+                NetworkCapabilities nc = vpn.updateCapabilities(defaultNetwork);
+                updateVpnCapabilities(vpn, nc);
             }
         }
     }
@@ -4523,6 +4548,7 @@
     private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
         @Override
         public void onReceive(Context context, Intent intent) {
+            ensureRunningOnConnectivityServiceThread();
             final String action = intent.getAction();
             final int userId = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, UserHandle.USER_NULL);
             final int uid = intent.getIntExtra(Intent.EXTRA_UID, -1);
@@ -5027,6 +5053,19 @@
         return getNetworkForRequest(mDefaultRequest.requestId);
     }
 
+    @Nullable
+    private Network getNetwork(@Nullable NetworkAgentInfo nai) {
+        return nai != null ? nai.network : null;
+    }
+
+    private void ensureRunningOnConnectivityServiceThread() {
+        if (mHandler.getLooper().getThread() != Thread.currentThread()) {
+            throw new IllegalStateException(
+                    "Not running on ConnectivityService thread: "
+                            + Thread.currentThread().getName());
+        }
+    }
+
     private boolean isDefaultNetwork(NetworkAgentInfo nai) {
         return nai == getDefaultNetwork();
     }
@@ -5620,6 +5659,8 @@
         updateTcpBufferSizes(newNetwork.linkProperties.getTcpBufferSizes());
         mDnsManager.setDefaultDnsSystemProperties(newNetwork.linkProperties.getDnsServers());
         notifyIfacesChangedForNetworkStats();
+        // Fix up the NetworkCapabilities of any VPNs that don't specify underlying networks.
+        updateAllVpnsCapabilities();
     }
 
     private void processListenRequests(NetworkAgentInfo nai, boolean capabilitiesChanged) {
@@ -6059,6 +6100,10 @@
             // doing.
             updateSignalStrengthThresholds(networkAgent, "CONNECT", null);
 
+            if (networkAgent.isVPN()) {
+                updateAllVpnsCapabilities();
+            }
+
             // Consider network even though it is not yet validated.
             final long now = SystemClock.elapsedRealtime();
             rematchNetworkAndRequests(networkAgent, ReapUnvalidatedNetworks.REAP, now);
@@ -6320,7 +6365,11 @@
             success = mVpns.get(user).setUnderlyingNetworks(networks);
         }
         if (success) {
-            mHandler.post(() -> notifyIfacesChangedForNetworkStats());
+            mHandler.post(() -> {
+                // Update VPN's capabilities based on updated underlying network set.
+                updateAllVpnsCapabilities();
+                notifyIfacesChangedForNetworkStats();
+            });
         }
         return success;
     }