[slaac] add IsEnabled() method and public API otIp6IsSlaacEnabled (#3667)

include/openthread/ip6.h

@@ -522,6 +522,17 @@ bool otIp6IsAddressUnspecified(const otIp6Address *aAddress);
  */
 otError otIp6SelectSourceAddress(otInstance *aInstance, otMessageInfo *aMessageInfo);
 
+/**
+ * This function indicates whether the SLAAC module is enabled or not.
+ *
+ * This function requires the build-time feature `OPENTHREAD_CONFIG_ENABLE_SLAAC` to be enabled.
+ *
+ * @retval TRUE    SLAAC module is enabled.
+ * @retval FALSE   SLAAC module is disabled.
+ *
+ */
+bool otIp6IsSlaacEnabled(otInstance *aInstance);
+
 /**
  * This function enables/disables the SLAAC module.
  *

src/core/api/ip6_api.cpp

@@ -272,6 +272,11 @@ exit:
 
 #if OPENTHREAD_CONFIG_ENABLE_SLAAC
 
+bool otIp6IsSlaacEnabled(otInstance *aInstance)
+{
+    return static_cast<Instance *>(aInstance)->Get<Utils::Slaac>().IsEnabled();
+}
+
 void otIp6SetSlaacEnabled(otInstance *aInstance, bool aEnabled)
 {
     Instance &    instance = *static_cast<Instance *>(aInstance);

src/core/utils/slaac_address.hpp

@@ -86,7 +86,7 @@ public:
     /**
      * This method enables the SLAAC module.
      *
-     * When enabled, new SLAAC addresses are generated and added fron on-mesh prefixes in network data.
+     * When enabled, new SLAAC addresses are generated and added from on-mesh prefixes in network data.
      *
      */
     void Enable(void);
@@ -99,6 +99,15 @@ public:
      */
     void Disable(void);
 
+    /**
+     * This method indicates whether SLAAC module is enabled or not.
+     *
+     * @retval TRUE    SLAAC module is enabled.
+     * @retval FALSE   SLAAC module is disabled.
+     *
+     */
+    bool IsEnabled(void) const { return mEnabled; }
+
     /**
      * This methods sets a SLAAC prefix filter handler.
      *