[dataset] introduce AffectsConnectivity() and public API (#13134)

This commit introduces helper methods to `MeshCoP::Dataset` to determine
if a given Dataset affects network connectivity or the Network Key.
It also adds a corresponding public API `otDatasetAffectsConnectivity()`.

A Dataset is considered to affect connectivity if it contains a
different Channel, PAN ID, Mesh Local Prefix, or Network Key than
the current values in use.

include/openthread/dataset.h

@@ -633,6 +633,24 @@ void otDatasetConvertToTlvs(const otOperationalDataset *aDataset, otOperationalD
  */
 otError otDatasetUpdateTlvs(const otOperationalDataset *aDataset, otOperationalDatasetTlvs *aDatasetTlvs);
 
+/**
+ * Indicates whether or not a given Operational Dataset (in TLVs format) affects connectivity.
+ *
+ * A Dataset affects connectivity if it contains a different Channel, PAN ID, Mesh Local Prefix, Network Key, or
+ * Security Policy than the current values in use.
+ *
+ * The following security policy changes are considered to affect connectivity:
+ * - Disabling routers (R bit: 1 to 0).
+ * - Enabling non-CCM routers (NCR bit: 0 to 1).
+ * - Increasing the version threshold for routing (VR field).
+ *
+ * @param[in]  aInstance     A pointer to an OpenThread instance.
+ * @param[in]  aDatasetTlvs  A pointer to Operational Dataset TLVs.
+ *
+ * @returns TRUE if @p aDatasetTlvs affects connectivity, FALSE otherwise.
+ */
+bool otDatasetAffectsConnectivity(otInstance *aInstance, const otOperationalDatasetTlvs *aDatasetTlvs);
+
 /**
  * @}
  */

include/openthread/instance.h

@@ -52,7 +52,7 @@ extern "C" {
  *
  * @note This number versions both OpenThread platform and user APIs.
  */
-#define OPENTHREAD_API_VERSION (598)
+#define OPENTHREAD_API_VERSION (599)
 
 /**
  * @addtogroup api-instance

src/core/api/dataset_api.cpp

@@ -228,3 +228,17 @@ otError otDatasetUpdateTlvs(const otOperationalDataset *aDataset, otOperationalD
 exit:
     return error;
 }
+
+bool otDatasetAffectsConnectivity(otInstance *aInstance, const otOperationalDatasetTlvs *aDatasetTlvs)
+{
+    bool             affects = false;
+    MeshCoP::Dataset dataset;
+
+    AssertPointerIsNotNull(aDatasetTlvs);
+
+    SuccessOrExit(dataset.SetFrom(*aDatasetTlvs));
+    affects = dataset.AffectsConnectivity(AsCoreType(aInstance));
+
+exit:
+    return affects;
+}

src/core/meshcop/dataset.cpp

@@ -611,6 +611,51 @@ exit:
     return isSubset;
 }
 
+bool Dataset::AffectsConnectivity(Instance &aInstance) const
+{
+    bool               affects = true;
+    ChannelTlvValue    channelValue;
+    Mac::PanId         panId;
+    Ip6::NetworkPrefix meshLocalPrefix;
+
+    if (Read<ChannelTlv>(channelValue) == kErrorNone)
+    {
+        VerifyOrExit(channelValue.GetChannel() == aInstance.Get<Mac::Mac>().GetPanChannel());
+    }
+
+    if (Read<PanIdTlv>(panId) == kErrorNone)
+    {
+        VerifyOrExit(panId == aInstance.Get<Mac::Mac>().GetPanId());
+    }
+
+    if (Read<MeshLocalPrefixTlv>(meshLocalPrefix) == kErrorNone)
+    {
+        VerifyOrExit(meshLocalPrefix == aInstance.Get<Mle::Mle>().GetMeshLocalPrefix());
+    }
+
+    VerifyOrExit(!AffectsNetworkKey(aInstance));
+
+    affects = false;
+
+exit:
+    return affects;
+}
+
+bool Dataset::AffectsNetworkKey(Instance &aInstance) const
+{
+    bool       affects = false;
+    NetworkKey networkKey;
+    NetworkKey localNetworkKey;
+
+    SuccessOrExit(Read<NetworkKeyTlv>(networkKey));
+
+    aInstance.Get<KeyManager>().GetNetworkKey(localNetworkKey);
+    affects = (networkKey != localNetworkKey);
+
+exit:
+    return affects;
+}
+
 const char *Dataset::TypeToString(Type aType) { return (aType == kActive) ? "Active" : "Pending"; }
 
 } // namespace MeshCoP

src/core/meshcop/dataset.hpp

@@ -655,6 +655,36 @@ public:
      */
     bool IsSubsetOf(const Dataset &aOther) const;
 
+    /**
+     * Indicates whether or not the Dataset affects connectivity.
+     *
+     * A Dataset affects connectivity if it contains a different Channel, PAN ID, Mesh Local Prefix, Network Key, or
+     * Security Policy than the current values in use.
+     *
+     * The following security policy changes are considered to affect connectivity:
+     * - Disabling routers (R bit: 1 to 0).
+     * - Enabling non-CCM routers (NCR bit: 0 to 1).
+     * - Increasing the version threshold for routing (VR field).
+     *
+     * @param[in] aInstance  The OpenThread instance.
+     *
+     * @retval TRUE   The Dataset affects connectivity.
+     * @retval FALSE  The Dataset does not affect connectivity.
+     */
+    bool AffectsConnectivity(Instance &aInstance) const;
+
+    /**
+     * Indicates whether or not the Dataset affects the Network Key.
+     *
+     * A Dataset affects the Network Key if it contains a different Network Key than the current value in use.
+     *
+     * @param[in] aInstance  The OpenThread instance.
+     *
+     * @retval TRUE   The Dataset affects the Network Key.
+     * @retval FALSE  The Dataset does not affect the Network Key.
+     */
+    bool AffectsNetworkKey(Instance &aInstance) const;
+
     /**
      * Converts a Dataset Type to a string.
      *

src/core/meshcop/dataset_manager_ftd.cpp

@@ -49,16 +49,12 @@ Error DatasetManager::ProcessSetOrReplaceRequest(MgmtCommand          aCommand,
                                                  const Coap::Message &aMessage,
                                                  RequestInfo         &aInfo) const
 {
-    Error              error = kErrorParse;
+    Error       error = kErrorParse;
-    Dataset            dataset;
+    Dataset     dataset;
-    OffsetRange        offsetRange;
+    OffsetRange offsetRange;
-    Timestamp          activeTimestamp;
+    Timestamp   activeTimestamp;
-    ChannelTlvValue    channelValue;
+    uint16_t    sessionId;
-    uint16_t           sessionId;
+    uint32_t    delayTimer;
-    Ip6::NetworkPrefix meshLocalPrefix;
-    NetworkKey         networkKey;
-    uint16_t           panId;
-    uint32_t           delayTimer;
 
     aInfo.Clear();
 
@@ -86,35 +82,8 @@ Error DatasetManager::ProcessSetOrReplaceRequest(MgmtCommand          aCommand,
     // Determine whether the new Dataset affects connectivity
     // or network key.
 
-    if ((dataset.Read<ChannelTlv>(channelValue) == kErrorNone) &&
+    aInfo.mAffectsConnectivity = dataset.AffectsConnectivity(GetInstance());
-        (channelValue.GetChannel() != Get<Mac::Mac>().GetPanChannel()))
+    aInfo.mAffectsNetworkKey   = dataset.AffectsNetworkKey(GetInstance());
-    {
-        aInfo.mAffectsConnectivity = true;
-    }
-
-    if ((dataset.Read<PanIdTlv>(panId) == kErrorNone) && (panId != Get<Mac::Mac>().GetPanId()))
-    {
-        aInfo.mAffectsConnectivity = true;
-    }
-
-    if ((dataset.Read<MeshLocalPrefixTlv>(meshLocalPrefix) == kErrorNone) &&
-        (meshLocalPrefix != Get<Mle::Mle>().GetMeshLocalPrefix()))
-    {
-        aInfo.mAffectsConnectivity = true;
-    }
-
-    if (dataset.Read<NetworkKeyTlv>(networkKey) == kErrorNone)
-    {
-        NetworkKey localNetworkKey;
-
-        Get<KeyManager>().GetNetworkKey(localNetworkKey);
-
-        if (networkKey != localNetworkKey)
-        {
-            aInfo.mAffectsConnectivity = true;
-            aInfo.mAffectsNetworkKey   = true;
-        }
-    }
 
     // Check active timestamp rollback. If there is no change to
     // network key, active timestamp must be ahead of local value.