From 0692aff5c5aba22060f35c8204dbb6707fdb25dc Mon Sep 17 00:00:00 2001
From: Patrick Rohr <prohr@google.com>
Date: Tue, 2 Jul 2024 11:53:17 -0700
Subject: [PATCH] Add more consistent null checks

This change moves the null check into the service implementation. Since
exceptions on oneway binder interfaces are ignored (across process), the
code was changed to just return early instead.

This also adds a couple of Objects.requireNonNull() assertions in
TetheringManager to assert the existing @NonNull annotation.

Test: TH
Bug: 337167681
Change-Id: I5301ed084bb26c2f910041e9b25314f8181718d1
---
 .../TetheringLib/src/android/net/TetheringManager.java      | 5 +++++
 .../src/com/android/networkstack/tethering/Tethering.java   | 6 ------
 .../android/networkstack/tethering/TetheringService.java    | 4 ++++
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
index 2963f87a36..e69f2ddeed 100644
--- a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
+++ b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
@@ -1353,6 +1353,9 @@ public class TetheringManager {
     @RequiresPermission(Manifest.permission.ACCESS_NETWORK_STATE)
     public void registerTetheringEventCallback(@NonNull Executor executor,
             @NonNull TetheringEventCallback callback) {
+        Objects.requireNonNull(executor);
+        Objects.requireNonNull(callback);
+
         final String callerPkg = mContext.getOpPackageName();
         Log.i(TAG, "registerTetheringEventCallback caller:" + callerPkg);
 
@@ -1507,6 +1510,8 @@ public class TetheringManager {
             Manifest.permission.ACCESS_NETWORK_STATE
     })
     public void unregisterTetheringEventCallback(@NonNull final TetheringEventCallback callback) {
+        Objects.requireNonNull(callback);
+
         final String callerPkg = mContext.getOpPackageName();
         Log.i(TAG, "unregisterTetheringEventCallback caller:" + callerPkg);
 
diff --git a/Tethering/src/com/android/networkstack/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
index 0ff89d3118..4631262dd1 100644
--- a/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -2400,9 +2400,6 @@ public class Tethering {
                 hasCallingPermission(NETWORK_SETTINGS)
                         || hasCallingPermission(PERMISSION_MAINLINE_NETWORK_STACK)
                         || hasCallingPermission(NETWORK_STACK);
-        if (callback == null) {
-            throw new NullPointerException();
-        }
         mHandler.post(() -> {
             mTetheringEventCallbacks.register(callback, new CallbackCookie(hasListPermission));
             final TetheringCallbackStartedParcel parcel = new TetheringCallbackStartedParcel();
@@ -2440,9 +2437,6 @@ public class Tethering {
 
     /** Unregister tethering event callback */
     void unregisterTetheringEventCallback(ITetheringEventCallback callback) {
-        if (callback == null) {
-            throw new NullPointerException();
-        }
         mHandler.post(() -> {
             mTetheringEventCallbacks.unregister(callback);
         });
diff --git a/Tethering/src/com/android/networkstack/tethering/TetheringService.java b/Tethering/src/com/android/networkstack/tethering/TetheringService.java
index 623f5023d1..93b350815e 100644
--- a/Tethering/src/com/android/networkstack/tethering/TetheringService.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringService.java
@@ -163,6 +163,8 @@ public class TetheringService extends Service {
         @Override
         public void registerTetheringEventCallback(ITetheringEventCallback callback,
                 String callerPkg) {
+            // Silently ignore call if the callback is null. This can only happen via reflection.
+            if (callback == null) return;
             try {
                 if (!hasTetherAccessPermission()) {
                     callback.onCallbackStopped(TETHER_ERROR_NO_ACCESS_TETHERING_PERMISSION);
@@ -175,6 +177,8 @@ public class TetheringService extends Service {
         @Override
         public void unregisterTetheringEventCallback(ITetheringEventCallback callback,
                 String callerPkg) {
+            // Silently ignore call if the callback is null. This can only happen via reflection.
+            if (callback == null) return;
             try {
                 if (!hasTetherAccessPermission()) {
                     callback.onCallbackStopped(TETHER_ERROR_NO_ACCESS_TETHERING_PERMISSION);