[spinel] add interface identifier of the Thread Domain Unicast Address (#6200)

This commit adds new spinel property to configure Interface Identifier
of the Thread Domain Unicast Address.

src/lib/spinel/spinel.h

@@ -1187,6 +1187,7 @@ enum
     SPINEL_CAP_MAC_RETRY_HISTOGRAM     = (SPINEL_CAP_OPENTHREAD__BEGIN + 12),
     SPINEL_CAP_MULTI_RADIO             = (SPINEL_CAP_OPENTHREAD__BEGIN + 13),
     SPINEL_CAP_SRP_CLIENT              = (SPINEL_CAP_OPENTHREAD__BEGIN + 14),
+    SPINEL_CAP_DUA                     = (SPINEL_CAP_OPENTHREAD__BEGIN + 15),
     SPINEL_CAP_OPENTHREAD__END         = 640,
 
     SPINEL_CAP_THREAD__BEGIN        = 1024,
@@ -2944,6 +2945,21 @@ enum
      */
     SPINEL_PROP_THREAD_DOMAIN_NAME = SPINEL_PROP_THREAD_EXT__BEGIN + 44,
 
+    /// Interface Identifier specified for Thread Domain Unicast Address.
+    /** Format: `A(C)` - Read-write
+     *
+     *   `A(C)`: Interface Identifier (8 bytes).
+     *
+     * Required capability: SPINEL_CAP_DUA
+     *
+     * If write to this property is performed without specified parameter
+     * the Interface Identifier of the Thread Domain Unicast Address will be cleared.
+     * If the DUA Interface Identifier is cleared on the NCP device,
+     * the get spinel property command will be returned successfully without specified parameter.
+     *
+     */
+    SPINEL_PROP_THREAD_DUA_ID = SPINEL_PROP_THREAD_EXT__BEGIN + 54,
+
     SPINEL_PROP_THREAD_EXT__END = 0x1600,
 
     SPINEL_PROP_IPV6__BEGIN = 0x60,

src/ncp/ncp_base.cpp

@@ -1931,6 +1931,10 @@ template <> otError NcpBase::HandlePropertyGet<SPINEL_PROP_CAPS>(void)
     SuccessOrExit(error = mEncoder.WriteUintPacked(SPINEL_CAP_SRP_CLIENT));
 #endif
 
+#if OPENTHREAD_CONFIG_DUA_ENABLE
+    SuccessOrExit(error = mEncoder.WriteUintPacked(SPINEL_CAP_DUA));
+#endif
+
 #endif // OPENTHREAD_MTD || OPENTHREAD_FTD
 
 exit:

src/ncp/ncp_base_dispatcher.cpp

@@ -310,6 +310,9 @@ NcpBase::PropertyHandler NcpBase::FindGetPropertyHandler(spinel_prop_key_t aKey)
 #if (OPENTHREAD_CONFIG_THREAD_VERSION >= OT_THREAD_VERSION_1_2)
         OT_NCP_GET_HANDLER_ENTRY(SPINEL_PROP_THREAD_DOMAIN_NAME),
 #endif
+#if OPENTHREAD_CONFIG_DUA_ENABLE
+        OT_NCP_GET_HANDLER_ENTRY(SPINEL_PROP_THREAD_DUA_ID),
+#endif
 #if OPENTHREAD_CONFIG_CHANNEL_MANAGER_ENABLE
         OT_NCP_GET_HANDLER_ENTRY(SPINEL_PROP_CHANNEL_MANAGER_NEW_CHANNEL),
         OT_NCP_GET_HANDLER_ENTRY(SPINEL_PROP_CHANNEL_MANAGER_DELAY),
@@ -541,6 +544,9 @@ NcpBase::PropertyHandler NcpBase::FindSetPropertyHandler(spinel_prop_key_t aKey)
 #if (OPENTHREAD_CONFIG_THREAD_VERSION >= OT_THREAD_VERSION_1_2)
         OT_NCP_SET_HANDLER_ENTRY(SPINEL_PROP_THREAD_DOMAIN_NAME),
 #endif
+#if OPENTHREAD_CONFIG_DUA_ENABLE
+        OT_NCP_SET_HANDLER_ENTRY(SPINEL_PROP_THREAD_DUA_ID),
+#endif
 #if OPENTHREAD_CONFIG_COMMISSIONER_ENABLE
         OT_NCP_SET_HANDLER_ENTRY(SPINEL_PROP_MESHCOP_COMMISSIONER_ANNOUNCE_BEGIN),
         OT_NCP_SET_HANDLER_ENTRY(SPINEL_PROP_MESHCOP_COMMISSIONER_ENERGY_SCAN),

src/ncp/ncp_base_ftd.cpp

@@ -351,6 +351,53 @@ exit:
 }
 #endif
 
+#if OPENTHREAD_CONFIG_DUA_ENABLE
+template <> otError NcpBase::HandlePropertyGet<SPINEL_PROP_THREAD_DUA_ID>(void)
+{
+    const otIp6InterfaceIdentifier *iid   = otThreadGetFixedDuaInterfaceIdentifier(mInstance);
+    otError                         error = OT_ERROR_NONE;
+
+    if (iid == nullptr)
+    {
+        // send empty response
+    }
+    else
+    {
+        for (size_t i = 0; i < sizeof(otIp6InterfaceIdentifier); i++)
+        {
+            SuccessOrExit(error = mEncoder.WriteUint8(iid->mFields.m8[i]));
+        }
+    }
+
+exit:
+    return error;
+}
+
+template <> otError NcpBase::HandlePropertySet<SPINEL_PROP_THREAD_DUA_ID>(void)
+{
+    otError error = OT_ERROR_NONE;
+
+    if (mDecoder.GetRemainingLength() == 0)
+    {
+        SuccessOrExit(error = otThreadSetFixedDuaInterfaceIdentifier(mInstance, nullptr));
+    }
+    else
+    {
+        otIp6InterfaceIdentifier iid;
+
+        for (size_t i = 0; i < sizeof(otIp6InterfaceIdentifier); i++)
+        {
+            SuccessOrExit(error = mDecoder.ReadUint8(iid.mFields.m8[i]));
+        }
+
+        SuccessOrExit(error = otThreadSetFixedDuaInterfaceIdentifier(mInstance, &iid));
+    }
+
+exit:
+    return error;
+}
+#endif // OPENTHREAD_CONFIG_DUA_ENABLE
+
 template <> otError NcpBase::HandlePropertyGet<SPINEL_PROP_NET_PSKC>(void)
 {
     return mEncoder.WriteData(otThreadGetPskc(mInstance)->m8, sizeof(spinel_net_pskc_t));