From 810ddb5e27bf364138072be48c583eceaa89b61e Mon Sep 17 00:00:00 2001
From: Nino Jagar <njagar@google.com>
Date: Mon, 5 Jun 2023 23:29:36 +0000
Subject: [PATCH] Add a reset mechanism into content protection processor

Bug: 275732576
Test: Added tests and manual end to end
Change-Id: I72238dae65b634c54cc62a0f2df4dff5816ae1c3
---
 .../ContentProtectionEventProcessor.java      | 26 ++++++++++
 .../ContentProtectionEventProcessorTest.java  | 52 +++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/core/java/android/view/contentprotection/ContentProtectionEventProcessor.java b/core/java/android/view/contentprotection/ContentProtectionEventProcessor.java
index e49df21692c58..b44abf3eb04d2 100644
--- a/core/java/android/view/contentprotection/ContentProtectionEventProcessor.java
+++ b/core/java/android/view/contentprotection/ContentProtectionEventProcessor.java
@@ -75,6 +75,8 @@ public class ContentProtectionEventProcessor {
                                     ContentCaptureEvent.TYPE_VIEW_DISAPPEARED,
                                     ContentCaptureEvent.TYPE_VIEW_TEXT_CHANGED)));
 
+    private static final int RESET_LOGIN_TOTAL_EVENTS_TO_PROCESS = 150;
+
     @NonNull private final RingBuffer<ContentCaptureEvent> mEventBuffer;
 
     @NonNull private final Handler mHandler;
@@ -93,6 +95,8 @@ public class ContentProtectionEventProcessor {
     @Nullable
     public Instant mLastFlushTime;
 
+    private int mResetLoginRemainingEventsToProcess;
+
     public ContentProtectionEventProcessor(
             @NonNull RingBuffer<ContentCaptureEvent> eventBuffer,
             @NonNull Handler handler,
@@ -130,6 +134,8 @@ public class ContentProtectionEventProcessor {
         mSuspiciousTextDetected |= isSuspiciousText(event);
         if (mPasswordFieldDetected && mSuspiciousTextDetected) {
             loginDetected();
+        } else {
+            maybeResetLoginFlags();
         }
     }
 
@@ -139,8 +145,28 @@ public class ContentProtectionEventProcessor {
                 || Instant.now().isAfter(mLastFlushTime.plus(MIN_DURATION_BETWEEN_FLUSHING))) {
             flush();
         }
+        resetLoginFlags();
+    }
+
+    @UiThread
+    private void resetLoginFlags() {
         mPasswordFieldDetected = false;
         mSuspiciousTextDetected = false;
+        mResetLoginRemainingEventsToProcess = 0;
+    }
+
+    @UiThread
+    private void maybeResetLoginFlags() {
+        if (mPasswordFieldDetected || mSuspiciousTextDetected) {
+            if (mResetLoginRemainingEventsToProcess <= 0) {
+                mResetLoginRemainingEventsToProcess = RESET_LOGIN_TOTAL_EVENTS_TO_PROCESS;
+            } else {
+                mResetLoginRemainingEventsToProcess--;
+                if (mResetLoginRemainingEventsToProcess <= 0) {
+                    resetLoginFlags();
+                }
+            }
+        }
     }
 
     @UiThread
diff --git a/core/tests/coretests/src/android/view/contentprotection/ContentProtectionEventProcessorTest.java b/core/tests/coretests/src/android/view/contentprotection/ContentProtectionEventProcessorTest.java
index 4adadf11903ee..39a2e0e048e83 100644
--- a/core/tests/coretests/src/android/view/contentprotection/ContentProtectionEventProcessorTest.java
+++ b/core/tests/coretests/src/android/view/contentprotection/ContentProtectionEventProcessorTest.java
@@ -91,6 +91,8 @@ public class ContentProtectionEventProcessorTest {
     private static final Set<Integer> EVENT_TYPES_TO_STORE =
             ImmutableSet.of(TYPE_VIEW_APPEARED, TYPE_VIEW_DISAPPEARED, TYPE_VIEW_TEXT_CHANGED);
 
+    private static final int RESET_LOGIN_TOTAL_EVENTS_TO_PROCESS = 150;
+
     @Rule public final MockitoRule mMockitoRule = MockitoJUnit.rule();
 
     @Mock private RingBuffer<ContentCaptureEvent> mMockEventBuffer;
@@ -231,6 +233,56 @@ public class ContentProtectionEventProcessorTest {
         verifyZeroInteractions(mMockContentCaptureManager);
     }
 
+    @Test
+    public void processEvent_loginDetected_belowResetLimit() throws Exception {
+        when(mMockEventBuffer.toArray()).thenReturn(BUFFERED_EVENTS);
+        mContentProtectionEventProcessor.mSuspiciousTextDetected = true;
+        ContentCaptureEvent event =
+                createAndroidPasswordFieldEvent(
+                        ANDROID_CLASS_NAME, InputType.TYPE_TEXT_VARIATION_PASSWORD);
+
+        for (int i = 0; i < RESET_LOGIN_TOTAL_EVENTS_TO_PROCESS; i++) {
+            mContentProtectionEventProcessor.processEvent(PROCESS_EVENT);
+        }
+
+        assertThat(mContentProtectionEventProcessor.mPasswordFieldDetected).isFalse();
+        assertThat(mContentProtectionEventProcessor.mSuspiciousTextDetected).isTrue();
+        verify(mMockEventBuffer, never()).clear();
+        verify(mMockEventBuffer, never()).toArray();
+
+        mContentProtectionEventProcessor.processEvent(event);
+
+        assertThat(mContentProtectionEventProcessor.mPasswordFieldDetected).isFalse();
+        assertThat(mContentProtectionEventProcessor.mSuspiciousTextDetected).isFalse();
+        verify(mMockEventBuffer).clear();
+        verify(mMockEventBuffer).toArray();
+        assertOnLoginDetected();
+    }
+
+    @Test
+    public void processEvent_loginDetected_aboveResetLimit() throws Exception {
+        mContentProtectionEventProcessor.mSuspiciousTextDetected = true;
+        ContentCaptureEvent event =
+                createAndroidPasswordFieldEvent(
+                        ANDROID_CLASS_NAME, InputType.TYPE_TEXT_VARIATION_PASSWORD);
+
+        for (int i = 0; i < RESET_LOGIN_TOTAL_EVENTS_TO_PROCESS + 1; i++) {
+            mContentProtectionEventProcessor.processEvent(PROCESS_EVENT);
+        }
+
+        assertThat(mContentProtectionEventProcessor.mPasswordFieldDetected).isFalse();
+        assertThat(mContentProtectionEventProcessor.mSuspiciousTextDetected).isFalse();
+        verify(mMockEventBuffer, never()).clear();
+        verify(mMockEventBuffer, never()).toArray();
+
+        mContentProtectionEventProcessor.processEvent(event);
+
+        assertThat(mContentProtectionEventProcessor.mPasswordFieldDetected).isTrue();
+        assertThat(mContentProtectionEventProcessor.mSuspiciousTextDetected).isFalse();
+        verify(mMockEventBuffer, never()).clear();
+        verify(mMockEventBuffer, never()).toArray();
+    }
+
     @Test
     public void processEvent_multipleLoginsDetected_belowFlushThreshold() throws Exception {
         when(mMockEventBuffer.toArray()).thenReturn(BUFFERED_EVENTS);