From 2e49f00e29d63a1c31e4115a9baafc75d2d35885 Mon Sep 17 00:00:00 2001
From: Kangping Dong <wgtdkp@google.com>
Date: Mon, 9 Jun 2025 20:05:49 +0800
Subject: [PATCH] [Thread] fix SparseArray hash for ActiveOperationalDataset

The existing ActiveOperationalDataset#hashCode has an issue that it's
depending on the SparseArray#hasCode which doesn't override the
Object#hashCode method. The consequence is that when the
ActiveOperationalDataset is used as a key in a container, there will
be a miss even if two ActiveOperationalDataset objects have the same
content.

This commit fixes this issue by using a dedicated
byteArraySparseArrayHasCode() method which computes the content hashcode
with Arrays.deepHashCode(). Also fixes the issue that mUnknownTlvs is
not counted in hashCode().

Flag: EXEMPT trivial bugfix
Change-Id: I085d3bf0bdf4bb73bb995fc28dd3857437f9743e
---
 .../net/thread/ActiveOperationalDataset.java       | 14 ++++++++++++--
 .../thread/cts/ActiveOperationalDatasetTest.java   |  9 +++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/thread/framework/java/android/net/thread/ActiveOperationalDataset.java b/thread/framework/java/android/net/thread/ActiveOperationalDataset.java
index 1b50ba7769..cd256c9991 100644
--- a/thread/framework/java/android/net/thread/ActiveOperationalDataset.java
+++ b/thread/framework/java/android/net/thread/ActiveOperationalDataset.java
@@ -363,6 +363,14 @@ public final class ActiveOperationalDataset implements Parcelable {
         outputStream.write(entries, 0, entries.length);
     }
 
+    private static int byteArraySparseArrayHashCode(@NonNull SparseArray<byte[]> array) {
+        int result = 0;
+        for (int i = 0; i < array.size(); i++) {
+            result = 31 * result + deepHashCode(array.keyAt(i), array.valueAt(i));
+        }
+        return result;
+    }
+
     private static boolean areByteSparseArraysEqual(
             @NonNull SparseArray<byte[]> first, @NonNull SparseArray<byte[]> second) {
         if (first == second) {
@@ -591,14 +599,16 @@ public final class ActiveOperationalDataset implements Parcelable {
 
     @Override
     public int hashCode() {
-        return deepHashCode(
+        // SparseArray<byte[]> is not hashable
+        int result = byteArraySparseArrayHashCode(mChannelMask);
+        result = result * 31 + byteArraySparseArrayHashCode(mUnknownTlvs);
+        return result * 31 + deepHashCode(
                 mActiveTimestamp,
                 mNetworkName,
                 mExtendedPanId,
                 mPanId,
                 mChannel,
                 mChannelPage,
-                mChannelMask,
                 mPskc,
                 mNetworkKey,
                 mMeshLocalPrefix,
diff --git a/thread/tests/cts/src/android/net/thread/cts/ActiveOperationalDatasetTest.java b/thread/tests/cts/src/android/net/thread/cts/ActiveOperationalDatasetTest.java
index 996d22d2e6..7a1b6fd86c 100644
--- a/thread/tests/cts/src/android/net/thread/cts/ActiveOperationalDatasetTest.java
+++ b/thread/tests/cts/src/android/net/thread/cts/ActiveOperationalDatasetTest.java
@@ -696,6 +696,15 @@ public final class ActiveOperationalDatasetTest {
         assertThat(dataset.getSecurityPolicy().getFlags()).isEqualTo(new byte[] {(byte) 0xff});
     }
 
+    @Test
+    public void hashCode_datasetsWithUnknownTlvs_hashCodeEquals() {
+        final byte[] datasetWithUnknownTlvs = addTlv(VALID_DATASET_TLVS, "AA01FFBB020102");
+        var dataset1 = ActiveOperationalDataset.fromThreadTlvs(datasetWithUnknownTlvs);
+        var dataset2 = ActiveOperationalDataset.fromThreadTlvs(datasetWithUnknownTlvs);
+
+        assertThat(dataset1.hashCode()).isEqualTo(dataset2.hashCode());
+    }
+
     @Test
     public void securityPolicy_invalidRotationTime_throwsIllegalArguments() {
         assertThrows(