[dataset] add generic Read<Tlv>() methods, refactor timestamp (#10059)

handling

This commit introduces several smaller changes to the `Dataset`
class:

- Provides template methods `Read<Tlv>()` for flexible reading of any
  TLV from dataset, mirroring the existing `Write<Tlv>()` methods.
- Replaces `SetTimestamp()` method with the `Write<Tlv>()` with
  specific timestamp TLVs
- Renames `GetTimestamp()` to `ReadTimestamp()`, aligning the naming
  convention with other methods.

src/core/meshcop/dataset.cpp

@@ -365,38 +365,9 @@ Error Dataset::SetFrom(const Info &aDatasetInfo)
     return error;
 }
 
-Error Dataset::GetTimestamp(Type aType, Timestamp &aTimestamp) const
+Error Dataset::ReadTimestamp(Type aType, Timestamp &aTimestamp) const
 {
-    Error      error = kErrorNone;
-    const Tlv *tlv;
-
-    if (aType == kActive)
-    {
-        tlv = FindTlv(Tlv::kActiveTimestamp);
-        VerifyOrExit(tlv != nullptr, error = kErrorNotFound);
-        aTimestamp = tlv->ReadValueAs<ActiveTimestampTlv>();
-    }
-    else
-    {
-        tlv = FindTlv(Tlv::kPendingTimestamp);
-        VerifyOrExit(tlv != nullptr, error = kErrorNotFound);
-        aTimestamp = tlv->ReadValueAs<PendingTimestampTlv>();
-    }
-
-exit:
-    return error;
-}
-
-void Dataset::SetTimestamp(Type aType, const Timestamp &aTimestamp)
-{
-    if (aType == kActive)
-    {
-        IgnoreError(Write<ActiveTimestampTlv>(aTimestamp));
-    }
-    else
-    {
-        IgnoreError(Write<PendingTimestampTlv>(aTimestamp));
-    }
+    return (aType == kActive) ? Read<ActiveTimestampTlv>(aTimestamp) : Read<PendingTimestampTlv>(aTimestamp);
 }
 
 Error Dataset::WriteTlv(Tlv::Type aType, const void *aValue, uint8_t aLength)

src/core/meshcop/dataset.hpp

@@ -297,6 +297,58 @@ public:
      */
     const Tlv *FindTlv(Tlv::Type aType) const;
 
+    /**
+     * Finds and reads a simple TLV in the Dataset.
+     *
+     * If the specified TLV type is not found, `kErrorNotFound` is reported.
+     *
+     * @tparam  SimpleTlvType   The simple TLV type (must be a sub-class of `SimpleTlvInfo`).
+     *
+     * @param[out] aValue       A reference to return the read TLV value.
+     *
+     * @retval kErrorNone      Successfully found and read the TLV value. @p aValue is updated.
+     * @retval kErrorNotFound  Could not find the TLV in the Dataset.
+     *
+     */
+    template <typename SimpleTlvType> Error Read(typename SimpleTlvType::ValueType &aValue) const
+    {
+        const Tlv *tlv = FindTlv(static_cast<Tlv::Type>(SimpleTlvType::kType));
+
+        return (tlv == nullptr) ? kErrorNotFound : (aValue = tlv->ReadValueAs<SimpleTlvType>(), kErrorNone);
+    }
+
+    /**
+     * Finds and reads an `uint` TLV in the Dataset.
+     *
+     * If the specified TLV type is not found, `kErrorNotFound` is reported.
+     *
+     * @tparam  UintTlvType     The integer simple TLV type (must be a sub-class of `UintTlvInfo`).
+     *
+     * @param[out] aValue       A reference to return the read TLV value.
+     *
+     * @retval kErrorNone      Successfully found and read the TLV value. @p aValue is updated.
+     * @retval kErrorNotFound  Could not find the TLV in the Dataset.
+     *
+     */
+    template <typename UintTlvType> Error Read(typename UintTlvType::UintValueType &aValue) const
+    {
+        const Tlv *tlv = FindTlv(static_cast<Tlv::Type>(UintTlvType::kType));
+
+        return (tlv == nullptr) ? kErrorNotFound : (aValue = tlv->ReadValueAs<UintTlvType>(), kErrorNone);
+    }
+
+    /**
+     * Reads the Timestamp (Active or Pending).
+     *
+     * @param[in]  aType       The type: active or pending.
+     * @param[out] aTimestamp  A reference to a `Timestamp` to output the value.
+     *
+     * @retval kErrorNone      Timestamp was read successfully. @p aTimestamp is updated.
+     * @retval kErrorNotFound  Could not find the requested Timestamp TLV.
+     *
+     */
+    Error ReadTimestamp(Type aType, Timestamp &aTimestamp) const;
+
     /**
      * Writes a TLV to the Dataset.
      *
@@ -429,27 +481,6 @@ public:
      */
     TimeMilli GetUpdateTime(void) const { return mUpdateTime; }
 
-    /**
-     * Gets the Timestamp (Active or Pending).
-     *
-     * @param[in]  aType       The type: active or pending.
-     * @param[out] aTimestamp  A reference to a `Timestamp` to output the value.
-     *
-     * @retval kErrorNone      Timestamp was read successfully. @p aTimestamp is updated.
-     * @retval kErrorNotFound  Could not find the requested Timestamp TLV.
-     *
-     */
-    Error GetTimestamp(Type aType, Timestamp &aTimestamp) const;
-
-    /**
-     * Sets the Timestamp value.
-     *
-     * @param[in] aType        The type: active or pending.
-     * @param[in] aTimestamp   A Timestamp.
-     *
-     */
-    void SetTimestamp(Type aType, const Timestamp &aTimestamp);
-
     /**
      * Reads the Dataset from a given message and checks that it is well-formed and valid.
      *

src/core/meshcop/dataset_local.cpp

@@ -82,7 +82,7 @@ Error DatasetLocal::Restore(Dataset &aDataset)
     SuccessOrExit(error);
 
     mSaved            = true;
-    mTimestampPresent = (aDataset.GetTimestamp(mType, mTimestamp) == kErrorNone);
+    mTimestampPresent = (aDataset.ReadTimestamp(mType, mTimestamp) == kErrorNone);
 
 exit:
     return error;
@@ -199,7 +199,7 @@ Error DatasetLocal::Save(const Dataset &aDataset)
         LogInfo("%s dataset set", Dataset::TypeToString(mType));
     }
 
-    mTimestampPresent = (aDataset.GetTimestamp(mType, mTimestamp) == kErrorNone);
+    mTimestampPresent = (aDataset.ReadTimestamp(mType, mTimestamp) == kErrorNone);
     mUpdateTime       = TimerMilli::GetNow();
 
 exit:

src/core/meshcop/dataset_manager.cpp

@@ -79,7 +79,7 @@ Error DatasetManager::Restore(void)
 
     SuccessOrExit(error = mLocal.Restore(dataset));
 
-    mTimestampValid = (dataset.GetTimestamp(GetType(), mTimestamp) == kErrorNone);
+    mTimestampValid = (dataset.ReadTimestamp(GetType(), mTimestamp) == kErrorNone);
 
     if (IsActiveDataset())
     {
@@ -121,7 +121,7 @@ Error DatasetManager::Save(const Dataset &aDataset)
     int   compare;
     bool  isNetworkKeyUpdated = false;
 
-    if (aDataset.GetTimestamp(GetType(), mTimestamp) == kErrorNone)
+    if (aDataset.ReadTimestamp(GetType(), mTimestamp) == kErrorNone)
     {
         mTimestampValid = true;
 
@@ -261,7 +261,7 @@ void DatasetManager::SendSet(void)
 
         IgnoreError(Get<PendingDatasetManager>().Read(pendingDataset));
 
-        if ((pendingDataset.GetTimestamp(Dataset::kActive, timestamp) == kErrorNone) &&
+        if ((pendingDataset.Read<ActiveTimestampTlv>(timestamp) == kErrorNone) &&
             (Timestamp::Compare(&timestamp, mLocal.GetTimestamp()) == 0))
         {
             // stop registration attempts during dataset transition
@@ -622,7 +622,7 @@ Error ActiveDatasetManager::Save(const Timestamp &aTimestamp,
     Dataset dataset;
 
     SuccessOrExit(error = dataset.ReadFromMessage(aMessage, aOffset, aLength));
-    dataset.SetTimestamp(Dataset::kActive, aTimestamp);
+    SuccessOrExit(error = dataset.Write<ActiveTimestampTlv>(aTimestamp));
     error = DatasetManager::Save(dataset);
 
 exit:
@@ -703,7 +703,7 @@ Error PendingDatasetManager::Save(const Timestamp &aTimestamp,
     Dataset dataset;
 
     SuccessOrExit(error = dataset.ReadFromMessage(aMessage, aOffset, aLength));
-    dataset.SetTimestamp(Dataset::kPending, aTimestamp);
+    SuccessOrExit(dataset.Write<PendingTimestampTlv>(aTimestamp));
     SuccessOrExit(error = DatasetManager::Save(dataset));
     StartDelayTimer();
 

src/core/meshcop/dataset_manager_ftd.cpp

@@ -443,7 +443,7 @@ void PendingDatasetManager::ApplyActiveDataset(const Timestamp &aTimestamp, Coap
 
     IgnoreError(dataset.Write<DelayTimerTlv>(Get<Leader>().GetDelayTimerMinimal()));
 
-    dataset.SetTimestamp(Dataset::kPending, aTimestamp);
+    IgnoreError(dataset.Write<PendingTimestampTlv>(aTimestamp));
     IgnoreError(DatasetManager::Save(dataset));
 
     StartDelayTimer();

src/core/meshcop/dataset_updater.cpp

@@ -139,14 +139,14 @@ void DatasetUpdater::PreparePendingDataset(void)
         }
 
         timestamp.AdvanceRandomTicks();
-        dataset.SetTimestamp(Dataset::kPending, timestamp);
+        IgnoreError(dataset.Write<PendingTimestampTlv>(timestamp));
     }
 
     {
         Timestamp timestamp = dataset.FindTlv(Tlv::kActiveTimestamp)->ReadValueAs<ActiveTimestampTlv>();
 
         timestamp.AdvanceRandomTicks();
-        dataset.SetTimestamp(Dataset::kActive, timestamp);
+        IgnoreError(dataset.Write<ActiveTimestampTlv>(timestamp));
     }
 
     SuccessOrExit(error = Get<PendingDatasetManager>().Save(dataset));