Ensure TetheringService binder is alive after system_server crash

servicemanager does not restart on a system_server crash, so
mConnectorSupplier might temporarily return a stale version of
TetheringService. Any operation on the stale binder causes a
DeadObjectException.

This change adds a check to ensure the binder is alive before use
and falls back to polling servicemanager.

Bug: 353920381
Bug: 271276384
Change-Id: I549d5a07966ebaed7e4a4ebe96e831dcac3b05bd
Signed-off-by: charid <dhoddeti.brahmachari@oppo.com>
diff --git a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
index bc771da..3292a7b 100644
--- a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
+++ b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
@@ -321,7 +321,9 @@
         // up and be sent from a worker thread; later, they are always sent from the caller thread.
         // Considering that it's just oneway binder calls, and ordering is preserved, this seems
         // better than inconsistent behavior persisting after boot.
-        if (connector != null) {
+        // If system server restarted, mConnectorSupplier might temporarily return a stale (i.e.
+        // dead) version of TetheringService.
+        if (connector != null && connector.isBinderAlive()) {
             mConnector = ITetheringConnector.Stub.asInterface(connector);
         } else {
             startPollingForConnector();
@@ -356,9 +358,8 @@
                 } catch (InterruptedException e) {
                     // Not much to do here, the system needs to wait for the connector
                 }
-
                 final IBinder connector = mConnectorSupplier.get();
-                if (connector != null) {
+                if (connector != null && connector.isBinderAlive()) {
                     onTetheringConnected(ITetheringConnector.Stub.asInterface(connector));
                     return;
                 }