[dua] support to specify iid for domain unicast address (#4900)

include/openthread/instance.h

@@ -53,7 +53,7 @@ extern "C" {
  * @note This number versions both OpenThread platform and user APIs.
  *
  */
-#define OPENTHREAD_API_VERSION (2)
+#define OPENTHREAD_API_VERSION (3)
 
 /**
  * @addtogroup api-instance

include/openthread/ip6.h

@@ -57,6 +57,24 @@ extern "C" {
 #define OT_IP6_IID_SIZE 8                              ///< Size of an IPv6 Interface Identifier (bytes)
 #define OT_IP6_ADDRESS_SIZE 16                         ///< Size of an IPv6 address (bytes)
 
+/**
+ * @struct otIp6InterfaceIdentifier
+ *
+ * This structure represents the Interface Identifier of an IPv6 address.
+ *
+ */
+OT_TOOL_PACKED_BEGIN
+struct otIp6InterfaceIdentifier
+{
+    uint8_t m8[OT_IP6_IID_SIZE]; ///< The Interface Identifier of an IPv6 address.
+} OT_TOOL_PACKED_END;
+
+/**
+ * This structure represents the Interface Identifier of an IPv6 address.
+ *
+ */
+typedef struct otIp6InterfaceIdentifier otIp6InterfaceIdentifier;
+
 /**
  * @struct otIp6Address
  *

include/openthread/thread.h

@@ -477,7 +477,7 @@ otError otThreadSetNetworkName(otInstance *aInstance, const char *aNetworkName);
 /**
  * Get the Thread Domain Name.
  *
- * This function is only availble since Thread 1.2.
+ * This function is only available since Thread 1.2.
  *
  * @param[in]  aInstance A pointer to an OpenThread instance.
  *
@@ -491,7 +491,7 @@ const char *otThreadGetDomainName(otInstance *aInstance);
 /**
  * Set the Thread Domain Name.
  *
- * This function is only availble since Thread 1.2.
+ * This function is only available since Thread 1.2.
  * This function succeeds only when Thread protocols are disabled.
  *
  * @param[in]  aInstance     A pointer to an OpenThread instance.
@@ -505,6 +505,35 @@ const char *otThreadGetDomainName(otInstance *aInstance);
  */
 otError otThreadSetDomainName(otInstance *aInstance, const char *aDomainName);
 
+/**
+ * Set/Clear the Interface Identifier manually specified for the Thread Domain Unicast Address.
+ *
+ * This function is only available since Thread 1.2 when `OPENTHREAD_CONFIG_DUA_ENABLE` is enabled.
+ *
+ * @param[in]  aInstance   A pointer to an OpenThread instance.
+ * @param[in]  aIid        A pointer to the Interface Identifier to set or NULL to clear.
+ *
+ * @retval OT_ERROR_NONE           Successfully set/cleared the Interface Identifier.
+ * @retval OT_ERROR_INVALID_ARGS   The specified Interface Identifier is reserved.
+ *
+ * @sa otThreadGetFixedDuaInterfaceIdentifier
+ */
+otError otThreadSetFixedDuaInterfaceIdentifier(otInstance *aInstance, const otIp6InterfaceIdentifier *aIid);
+
+/**
+ * Get the Interface Identifier manually specified for the Thread Domain Unicast Address.
+ *
+ * This function is only available since Thread 1.2 when `OPENTHREAD_CONFIG_DUA_ENABLE` is enabled.
+ *
+ * @param[in]  aInstance A pointer to an OpenThread instance.
+ *
+ * @returns A pointer to the Interface Identifier which was set manually, or NULL if none was set.
+ *
+ * @sa otThreadSetFixedDuaInterfaceIdentifier
+ *
+ */
+const otIp6InterfaceIdentifier *otThreadGetFixedDuaInterfaceIdentifier(otInstance *aInstance);
+
 /**
  * Get the thrKeySequenceCounter.
  *