[dataset] simplify IsSubsetOf() (#10292)

This commit adds a method `Dataset::IsSubsetOf()` to check whether one
dataset is a subset of another. A dataset is considered a subset if
all its TLVs, excluding Active/Pending Timestamp and Delay Timer
TLVs, are present in the other dataset with exactly matching values.

This new method simplifies `Dataset::Info::IsSubsetOf()`. The unit
test `test_dataset` is updated to validate the `IsSubsetOf()()`
method.

src/core/meshcop/dataset.cpp

@@ -103,57 +103,13 @@ exit:
 
 bool Dataset::Info::IsSubsetOf(const Info &aOther) const
 {
-    bool isSubset = false;
+    Dataset dataset;
+    Dataset other;
 
-    if (IsPresent<kNetworkKey>())
-    {
-        VerifyOrExit(aOther.IsPresent<kNetworkKey>() && Get<kNetworkKey>() == aOther.Get<kNetworkKey>());
-    }
+    dataset.SetFrom(*this);
+    other.SetFrom(aOther);
 
-    if (IsPresent<kNetworkName>())
-    {
-        VerifyOrExit(aOther.IsPresent<kNetworkName>() && Get<kNetworkName>() == aOther.Get<kNetworkName>());
-    }
-
-    if (IsPresent<kExtendedPanId>())
-    {
-        VerifyOrExit(aOther.IsPresent<kExtendedPanId>() && Get<kExtendedPanId>() == aOther.Get<kExtendedPanId>());
-    }
-
-    if (IsPresent<kMeshLocalPrefix>())
-    {
-        VerifyOrExit(aOther.IsPresent<kMeshLocalPrefix>() && Get<kMeshLocalPrefix>() == aOther.Get<kMeshLocalPrefix>());
-    }
-
-    if (IsPresent<kPanId>())
-    {
-        VerifyOrExit(aOther.IsPresent<kPanId>() && Get<kPanId>() == aOther.Get<kPanId>());
-    }
-
-    if (IsPresent<kChannel>())
-    {
-        VerifyOrExit(aOther.IsPresent<kChannel>() && Get<kChannel>() == aOther.Get<kChannel>());
-    }
-
-    if (IsPresent<kPskc>())
-    {
-        VerifyOrExit(aOther.IsPresent<kPskc>() && Get<kPskc>() == aOther.Get<kPskc>());
-    }
-
-    if (IsPresent<kSecurityPolicy>())
-    {
-        VerifyOrExit(aOther.IsPresent<kSecurityPolicy>() && Get<kSecurityPolicy>() == aOther.Get<kSecurityPolicy>());
-    }
-
-    if (IsPresent<kChannelMask>())
-    {
-        VerifyOrExit(aOther.IsPresent<kChannelMask>() && Get<kChannelMask>() == aOther.Get<kChannelMask>());
-    }
-
-    isSubset = true;
-
-exit:
-    return isSubset;
+    return dataset.IsSubsetOf(other);
 }
 
 Dataset::Dataset(void)
@@ -585,6 +541,31 @@ void Dataset::RemoveTlv(Tlv *aTlv)
     }
 }
 
+bool Dataset::IsSubsetOf(const Dataset &aOther) const
+{
+    bool isSubset = false;
+
+    for (const Tlv *tlv = GetTlvsStart(); tlv < GetTlvsEnd(); tlv = tlv->GetNext())
+    {
+        const Tlv *otherTlv;
+
+        if ((tlv->GetType() == Tlv::kActiveTimestamp) || (tlv->GetType() == Tlv::kPendingTimestamp) ||
+            (tlv->GetType() == Tlv::kDelayTimer))
+        {
+            continue;
+        }
+
+        otherTlv = aOther.FindTlv(tlv->GetType());
+        VerifyOrExit(otherTlv != nullptr);
+        VerifyOrExit(memcmp(tlv, otherTlv, tlv->GetSize()) == 0);
+    }
+
+    isSubset = true;
+
+exit:
+    return isSubset;
+}
+
 const char *Dataset::TypeToString(Type aType) { return (aType == kActive) ? "Active" : "Pending"; }
 
 #if OPENTHREAD_CONFIG_PLATFORM_KEY_REFERENCES_ENABLE

src/core/meshcop/dataset.hpp

@@ -220,7 +220,7 @@ public:
          *
          * @param[in] aOther   The other Dataset to check against.
          *
-         * @retval TRUE   The current dataset is a subset of @p aOther.
+         * @retval TRUE   The current Dataset is a subset of @p aOther.
          * @retval FALSE  The current Dataset is not a subset of @p aOther.
          *
          */
@@ -672,6 +672,20 @@ public:
      */
     const Tlv *GetTlvsEnd(void) const { return reinterpret_cast<const Tlv *>(mTlvs + mLength); }
 
+    /**
+     * Determines whether this Dataset is a subset of another Dataset.
+     *
+     * The Dataset is considered a subset if all of its TLVs, excluding Active/Pending Timestamp and Delay Timer TLVs,
+     * are present in the @p aOther Dataset and the TLV values match exactly.
+     *
+     * @param[in] aOther   The other Dataset to check against.
+     *
+     * @retval TRUE   The current dataset is a subset of @p aOther.
+     * @retval FALSE  The current Dataset is not a subset of @p aOther.
+     *
+     */
+    bool IsSubsetOf(const Dataset &aOther) const;
+
     /**
      * Converts a Dataset Type to a string.
      *

tests/unit/test_dataset.cpp

@@ -224,6 +224,41 @@ void TestDataset(void)
     VerifyOrQuit(memcmp(dataset.GetBytes() + sizeof(kTlvBytes), kTlvBytes, sizeof(kTlvBytes)) == 0);
 
     VerifyOrQuit(dataset.ValidateTlvs() == kErrorParse);
+
+    // Validate `IsSubsetOf()`
+
+    SuccessOrQuit(dataset.SetFrom(kTlvBytes, sizeof(kTlvBytes)));
+
+    datasetInfo.Clear();
+    datasetInfo.mComponents.mIsPanIdPresent      = true;
+    datasetInfo.mComponents.mIsNetworkKeyPresent = true;
+    datasetInfo.mPanId                           = 0xface;
+    datasetInfo.mNetworkKey                      = kNetworkKey;
+
+    dataset2.SetFrom(datasetInfo);
+
+    SuccessOrQuit(dataset2.ValidateTlvs());
+    SuccessOrQuit(dataset.ValidateTlvs());
+
+    VerifyOrQuit(dataset2.IsSubsetOf(dataset));
+    VerifyOrQuit(!dataset.IsSubsetOf(dataset2));
+
+    datasetInfo.mComponents.mIsActiveTimestampPresent  = true;
+    datasetInfo.mComponents.mIsPendingTimestampPresent = true;
+    datasetInfo.mComponents.mIsDelayPresent            = true;
+    datasetInfo.mActiveTimestamp.mSeconds              = 0xffff;
+    datasetInfo.mPendingTimestamp.mSeconds             = 0x1000;
+    datasetInfo.mDelay                                 = 5000;
+    dataset2.SetFrom(datasetInfo);
+
+    VerifyOrQuit(dataset2.IsSubsetOf(dataset));
+    VerifyOrQuit(!dataset.IsSubsetOf(dataset2));
+
+    datasetInfo.mPanId = 0xcafe;
+    dataset2.SetFrom(datasetInfo);
+
+    VerifyOrQuit(!dataset2.IsSubsetOf(dataset));
+    VerifyOrQuit(!dataset.IsSubsetOf(dataset2));
 }
 
 } // namespace MeshCoP