[ncp] add SLAAC related spinel capability and property (#3667)

This commit adds `SPINEL_CAP_SLAAC` which indicates to host whether
SLAAC feature is supported. It also adds `SPINEL_PROP_SLAAC_ENABLED`
spinel property to let host enable/disable SLAAC module at run-time.

src/ncp/ncp_base.cpp

@@ -1787,6 +1787,10 @@ template <> otError NcpBase::HandlePropertyGet<SPINEL_PROP_CAPS>(void)
     SuccessOrExit(error = mEncoder.WriteUintPacked(SPINEL_CAP_OOB_STEERING_DATA));
 #endif
 
+#if OPENTHREAD_CONFIG_ENABLE_SLAAC
+    SuccessOrExit(error = mEncoder.WriteUintPacked(SPINEL_CAP_SLAAC));
+#endif
+
 #if OPENTHREAD_CONFIG_NCP_ENABLE_PEEK_POKE
     SuccessOrExit(error = mEncoder.WriteUintPacked(SPINEL_CAP_PEEK_POKE));
 #endif

src/ncp/ncp_base_dispatcher.cpp

@@ -511,6 +511,11 @@ NcpBase::PropertyHandler NcpBase::FindGetPropertyHandler(spinel_prop_key_t aKey)
         handler = &NcpBase::HandlePropertyGet<SPINEL_PROP_RCP_VERSION>;
         break;
 #endif
+#if OPENTHREAD_CONFIG_ENABLE_SLAAC
+    case SPINEL_PROP_SLAAC_ENABLED:
+        handler = &NcpBase::HandlePropertyGet<SPINEL_PROP_SLAAC_ENABLED>;
+        break;
+#endif
 #endif // OPENTHREAD_MTD || OPENTHREAD_FTD
 
         // --------------------------------------------------------------------------
@@ -842,6 +847,11 @@ NcpBase::PropertyHandler NcpBase::FindSetPropertyHandler(spinel_prop_key_t aKey)
         handler = &NcpBase::HandlePropertySet<SPINEL_PROP_CHILD_SUPERVISION_CHECK_TIMEOUT>;
         break;
 #endif
+#if OPENTHREAD_CONFIG_ENABLE_SLAAC
+    case SPINEL_PROP_SLAAC_ENABLED:
+        handler = &NcpBase::HandlePropertySet<SPINEL_PROP_SLAAC_ENABLED>;
+        break;
+#endif
 #endif // OPENTHREAD_MTD || OPENTHREAD_FTD
 
         // --------------------------------------------------------------------------

src/ncp/ncp_base_mtd.cpp

@@ -2833,6 +2833,27 @@ template <> otError NcpBase::HandlePropertyGet<SPINEL_PROP_RCP_VERSION>(void)
 
 #endif // OPENTHREAD_ENABLE_POSIX_APP
 
+#if OPENTHREAD_CONFIG_ENABLE_SLAAC
+
+template <> otError NcpBase::HandlePropertyGet<SPINEL_PROP_SLAAC_ENABLED>(void)
+{
+    return mEncoder.WriteBool(otIp6IsSlaacEnabled(mInstance));
+}
+
+template <> otError NcpBase::HandlePropertySet<SPINEL_PROP_SLAAC_ENABLED>(void)
+{
+    otError error = OT_ERROR_NONE;
+    bool    enabled;
+
+    SuccessOrExit(error = mDecoder.ReadBool(enabled));
+    otIp6SetSlaacEnabled(mInstance, enabled);
+
+exit:
+    return error;
+}
+
+#endif // OPENTHREAD_CONFIG_ENABLE_SLAAC
+
 #if OPENTHREAD_ENABLE_LEGACY
 
 void NcpBase::RegisterLegacyHandlers(const otNcpLegacyHandlers *aHandlers)

src/ncp/spinel.c

@@ -1851,6 +1851,10 @@ const char *spinel_prop_key_to_cstr(spinel_prop_key_t prop_key)
         ret = "PARENT_RESPONSE_INFO";
         break;
 
+    case SPINEL_PROP_SLAAC_ENABLED:
+        ret = "SLAAC_ENABLED";
+        break;
+
     case SPINEL_PROP_UART_BITRATE:
         ret = "UART_BITRATE";
         break;
@@ -2480,6 +2484,10 @@ const char *spinel_capability_to_cstr(unsigned int capability)
         ret = "POSIX_APP";
         break;
 
+    case SPINEL_CAP_SLAAC:
+        ret = "SLAAC";
+        break;
+
     case SPINEL_CAP_ERROR_RATE_TRACKING:
         ret = "ERROR_RATE_TRACKING";
         break;

src/ncp/spinel.h

@@ -778,6 +778,7 @@ enum
     SPINEL_CAP_TIME_SYNC               = (SPINEL_CAP_OPENTHREAD__BEGIN + 7),
     SPINEL_CAP_CHILD_SUPERVISION       = (SPINEL_CAP_OPENTHREAD__BEGIN + 8),
     SPINEL_CAP_POSIX_APP               = (SPINEL_CAP_OPENTHREAD__BEGIN + 9),
+    SPINEL_CAP_SLAAC                   = (SPINEL_CAP_OPENTHREAD__BEGIN + 10),
     SPINEL_CAP_OPENTHREAD__END         = 640,
 
     SPINEL_CAP_THREAD__BEGIN        = 1024,
@@ -3025,6 +3026,17 @@ typedef enum
      */
     SPINEL_PROP_PARENT_RESPONSE_INFO = SPINEL_PROP_OPENTHREAD__BEGIN + 13,
 
+    /// SLAAC enabled
+    /** Format `b` - Read-Write
+     *  Required capability: `SPINEL_CAP_SLAAC`
+     *
+     * This property allows the host to enable/disable SLAAC module on NCP at run-time. When SLAAC module is enabled,
+     * SLAAC addresses (based on on-mesh prefixes in Network Data) are added to the interface. When SLAAC module is
+     * disabled any previously added SLAAC address is removed.
+     *
+     */
+    SPINEL_PROP_SLAAC_ENABLED = SPINEL_PROP_OPENTHREAD__BEGIN + 14,
+
     SPINEL_PROP_OPENTHREAD__END = 0x2000,
 
     SPINEL_PROP_INTERFACE__BEGIN = 0x100,