[routing-manager] generate random nat64 prefix and add it to netdata (#7232)

This commit generates a random NAT64 prefix and adds the prefix to
NetworkData if none exits. The prefix will be saved in Settings for
recovery.

It also adds a new CLI command `br nat64prefix` to show the local
nat64 prefix.

A new config OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE is defined
and used to guard the change.

This initial implementation only supports a single BR.

etc/cmake/options.cmake

@@ -82,6 +82,11 @@ if(OT_BORDER_ROUTING)
     target_compile_definitions(ot-config INTERFACE "OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE=1")
 endif()
 
+option(OT_BORDER_ROUTING_NAT64 "enable border routing NAT64 support")
+if(OT_BORDER_ROUTING_NAT64)
+    target_compile_definitions(ot-config INTERFACE "OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE=1")
+endif()
+
 if(NOT OT_EXTERNAL_MBEDTLS)
     set(OT_MBEDTLS mbedtls)
     target_compile_definitions(ot-config INTERFACE "OPENTHREAD_CONFIG_ENABLE_BUILTIN_MBEDTLS=1")

examples/README.md

@@ -11,6 +11,8 @@ This page lists the available common switches with description. Unless stated ot
 | BIG_ENDIAN | OT_BIG_ENDIAN | Allows the host platform to use big-endian byte order. |
 | BORDER_AGENT | OT_BORDER_AGENT | Enables support for border agent. In most cases, enable this switch if you are building On-mesh Commissioner or Border Router with External Commissioning support. |
 | BORDER_ROUTER | OT_BORDER_ROUTER | Enables support for Border Router. This switch is usually combined with the BORDER_AGENT and UDP_FORWARD (or PLATFORM_UDP in case of RCP design) switches to build Border Router device. |
+| BORDER_ROUTING | OT_BORDER_ROUTING | Enables bi-directional border routing between Thread and Infrastructure networks for Border Router. |
+| BORDER_ROUTING_NAT64 | OT_BORDER_ROUTING_NAT64 | Enables NAT64 border routing support for Border Router. |
 | BUILTIN_MBEDTLS_MANAGEMENT | OT_BUILTIN_MBEDTLS_MANAGEMENT | Enables the built-in mbedTLS management. Enable this switch if the external mbedTLS is used, but mbedTLS memory allocation and debug config should be managed internally by OpenThread. |
 | CHANNEL_MANAGER | OT_CHANNEL_MANAGER | Enables support for channel manager. Enable this switch on devices that are supposed to request a Thread network channel change. This switch should be used only with an FTD build. |
 | CHANNEL_MONITOR | OT_CHANNEL_MONITOR | Enables support for channel monitor. Enable this switch on devices that are supposed to determine the cleaner channels. |

examples/common-switches.mk

@@ -34,6 +34,7 @@ BIG_ENDIAN                ?= 0
 BORDER_AGENT              ?= 0
 BORDER_ROUTER             ?= 0
 BORDER_ROUTING            ?= 0
+BORDER_ROUTING_NAT64	  ?= 0
 COAP                      ?= 0
 COAP_BLOCK                ?= 0
 COAP_OBSERVE              ?= 0
@@ -116,6 +117,10 @@ ifeq ($(BORDER_ROUTING),1)
 COMMONCFLAGS                   += -DOPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE=1
 endif
 
+ifeq ($(BORDER_ROUTING_NAT64),1)
+COMMONCFLAGS		       += -DOPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE=1
+endif
+
 ifeq ($(COAP),1)
 COMMONCFLAGS                   += -DOPENTHREAD_CONFIG_COAP_API_ENABLE=1
 endif

include/openthread/border_router.h

@@ -117,6 +117,23 @@ otError otBorderRoutingGetOmrPrefix(otInstance *aInstance, otIp6Prefix *aPrefix)
  */
 otError otBorderRoutingGetOnLinkPrefix(otInstance *aInstance, otIp6Prefix *aPrefix);
 
+/**
+ * This function returns the local NAT64 prefix.
+ *
+ * This prefix might not be advertised in the Thread network.
+ *
+ * This function is only available when `OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE`
+ * is enabled.
+ *
+ * @param[in]   aInstance   A pointer to an OpenThread instance.
+ * @param[out]  aPrefix     A pointer to where the prefix will be output to.
+ *
+ * @retval  OT_ERROR_INVALID_STATE  The Border Routing Manager is not initialized yet.
+ * @retval  OT_ERROR_NONE           Successfully retrieved the NAT64 prefix.
+ *
+ */
+otError otBorderRoutingGetNat64Prefix(otInstance *aInstance, otIp6Prefix *aPrefix);
+
 /**
  * This method provides a full or stable copy of the local Thread Network Data.
  *

include/openthread/instance.h

@@ -53,7 +53,7 @@ extern "C" {
  * @note This number versions both OpenThread platform and user APIs.
  *
  */
-#define OPENTHREAD_API_VERSION (184)
+#define OPENTHREAD_API_VERSION (185)
 
 /**
  * @addtogroup api-instance

include/openthread/platform/settings.h

@@ -54,7 +54,7 @@ extern "C" {
 /**
  * This enumeration defines the keys of settings.
  *
- * Note: When adding a new setings key, if the settings corresponding to the key contains security sensitive
+ * Note: When adding a new settings key, if the settings corresponding to the key contains security sensitive
  *       information, the developer MUST add the key to the array `kCriticalKeys`.
  *
  */
@@ -73,6 +73,7 @@ enum
     OT_SETTINGS_KEY_SRP_ECDSA_KEY        = 0x000b, ///< SRP client ECDSA public/private key pair.
     OT_SETTINGS_KEY_SRP_CLIENT_INFO      = 0x000c, ///< The SRP client info (selected SRP server address).
     OT_SETTINGS_KEY_SRP_SERVER_INFO      = 0x000d, ///< The SRP server info (UDP port).
+    OT_SETTINGS_KEY_NAT64_PREFIX         = 0x000e, ///< NAT64 prefix.
 };
 
 /**

script/check-scan-build

@@ -37,6 +37,7 @@ readonly OT_BUILD_OPTIONS=(
     "-DOT_BORDER_AGENT=ON"
     "-DOT_BORDER_ROUTER=ON"
     "-DOT_BORDER_ROUTING=ON"
+    "-DOT_BORDER_ROUTING_NAT64=ON"
     "-DOT_COAP=ON"
     "-DOT_COAP_BLOCK=ON"
     "-DOT_COAP_OBSERVE=ON"

script/make-pretty

@@ -83,6 +83,7 @@ readonly OT_CLANG_TIDY_BUILD_OPTS=(
     '-DOT_BORDER_AGENT=ON'
     '-DOT_BORDER_ROUTER=ON'
     '-DOT_BORDER_ROUTING=ON'
+    '-DOT_BORDER_ROUTING_NAT64=ON'
     '-DOT_CHANNEL_MANAGER=ON'
     '-DOT_CHANNEL_MONITOR=ON'
     '-DOT_CHILD_SUPERVISION=ON'

src/cli/README.md

@@ -393,6 +393,18 @@ fd41:2650:a6f5:0::/64
 Done
 ```
 
+### br nat64prefix
+
+Get the local NAT64 prefix of the Border Router.
+
+`OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE` is required.
+
+```bash
+> br nat64prefix
+fd14:1078:b3d5:b0b0:0:0::/96
+Done
+```
+
 ### bufferinfo
 
 Show the current message buffer information.

src/cli/cli.cpp

@@ -494,6 +494,15 @@ otError Interpreter::ProcessBorderRouting(Arg aArgs[])
         SuccessOrExit(error = otBorderRoutingGetOnLinkPrefix(GetInstancePtr(), &onLinkPrefix));
         OutputIp6PrefixLine(onLinkPrefix);
     }
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+    else if (aArgs[0] == "nat64prefix")
+    {
+        otIp6Prefix nat64Prefix;
+
+        SuccessOrExit(error = otBorderRoutingGetNat64Prefix(GetInstancePtr(), &nat64Prefix));
+        OutputIp6PrefixLine(nat64Prefix);
+    }
+#endif // OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
     else
     {
         error = OT_ERROR_INVALID_COMMAND;

src/core/api/border_router_api.cpp

@@ -64,7 +64,13 @@ otError otBorderRoutingGetOnLinkPrefix(otInstance *aInstance, otIp6Prefix *aPref
     return AsCoreType(aInstance).Get<BorderRouter::RoutingManager>().GetOnLinkPrefix(AsCoreType(aPrefix));
 }
 
-#endif
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+otError otBorderRoutingGetNat64Prefix(otInstance *aInstance, otIp6Prefix *aPrefix)
+{
+    return AsCoreType(aInstance).Get<BorderRouter::RoutingManager>().GetNat64Prefix(AsCoreType(aPrefix));
+}
+#endif // OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+#endif // OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE
 
 otError otBorderRouterGetNetData(otInstance *aInstance, bool aStable, uint8_t *aData, uint8_t *aDataLength)
 {

src/core/border_router/routing_manager.cpp

@@ -64,6 +64,7 @@ RoutingManager::RoutingManager(Instance &aInstance)
     , mInfraIfIndex(0)
     , mIsAdvertisingLocalOnLinkPrefix(false)
     , mOnLinkPrefixDeprecateTimer(aInstance, HandleOnLinkPrefixDeprecateTimer)
+    , mIsAdvertisingLocalNat64Prefix(false)
     , mTimeRouterAdvMessageLastUpdate(TimerMilli::GetNow())
     , mLearntRouterAdvMessageFromHost(false)
     , mDiscoveredPrefixInvalidTimer(aInstance, HandleDiscoveredPrefixInvalidTimer)
@@ -79,6 +80,8 @@ RoutingManager::RoutingManager(Instance &aInstance)
     mLocalOmrPrefix.Clear();
 
     mLocalOnLinkPrefix.Clear();
+
+    mLocalNat64Prefix.Clear();
 }
 
 Error RoutingManager::Init(uint32_t aInfraIfIndex, bool aInfraIfIsRunning)
@@ -90,6 +93,9 @@ Error RoutingManager::Init(uint32_t aInfraIfIndex, bool aInfraIfIsRunning)
 
     SuccessOrExit(error = LoadOrGenerateRandomOmrPrefix());
     SuccessOrExit(error = LoadOrGenerateRandomOnLinkPrefix());
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+    SuccessOrExit(error = LoadOrGenerateRandomNat64Prefix());
+#endif
 
     mInfraIfIndex = aInfraIfIndex;
 
@@ -141,6 +147,19 @@ exit:
     return error;
 }
 
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+Error RoutingManager::GetNat64Prefix(Ip6::Prefix &aPrefix)
+{
+    Error error = kErrorNone;
+
+    VerifyOrExit(IsInitialized(), error = kErrorInvalidState);
+    aPrefix = mLocalNat64Prefix;
+
+exit:
+    return error;
+}
+#endif
+
 Error RoutingManager::LoadOrGenerateRandomOmrPrefix(void)
 {
     Error error = kErrorNone;
@@ -151,6 +170,7 @@ Error RoutingManager::LoadOrGenerateRandomOmrPrefix(void)
 
         otLogNoteBr("No valid OMR prefix found in settings, generating new one");
 
+        // TODO: generate OMR prefix from the /48 BR ULA prefix
         error = randomOmrPrefix.GenerateRandomUla();
         if (error != kErrorNone)
         {
@@ -195,6 +215,39 @@ exit:
     return error;
 }
 
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+Error RoutingManager::LoadOrGenerateRandomNat64Prefix(void)
+{
+    Error error = kErrorNone;
+
+    if (Get<Settings>().Read<Settings::Nat64Prefix>(mLocalNat64Prefix) != kErrorNone ||
+        !mLocalNat64Prefix.IsValidNat64())
+    {
+        Ip6::NetworkPrefix randomNat64Prefix;
+        constexpr uint8_t  nat64PrefixLength = 96;
+
+        otLogNoteBr("No valid NAT64 prefix found in settings, generating new one");
+
+        // TODO: generate NAT64 prefix from the /48 BR ULA prefix
+        error = randomNat64Prefix.GenerateRandomUla();
+        if (error != kErrorNone)
+        {
+            otLogCritBr("Failed to generate random NAT64 prefix");
+            ExitNow();
+        }
+
+        mLocalNat64Prefix.Clear();
+        mLocalNat64Prefix.Set(randomNat64Prefix);
+        mLocalNat64Prefix.SetLength(nat64PrefixLength);
+
+        IgnoreError(Get<Settings>().Save<Settings::Nat64Prefix>(mLocalNat64Prefix));
+    }
+
+exit:
+    return error;
+}
+#endif
+
 void RoutingManager::EvaluateState(void)
 {
     if (mIsEnabled && Get<Mle::MleRouter>().IsAttached() && mInfraIfIsRunning)
@@ -233,6 +286,13 @@ void RoutingManager::Stop(void)
         DeprecateOnLinkPrefix();
     }
 
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+    if (mIsAdvertisingLocalNat64Prefix)
+    {
+        RemoveExternalRoute(mLocalNat64Prefix);
+        mIsAdvertisingLocalNat64Prefix = false;
+    }
+#endif
     // Use empty OMR & on-link prefixes to invalidate possible advertised prefixes.
     SendRouterAdvertisement(OmrPrefixArray(), nullptr);
 
@@ -429,7 +489,7 @@ Error RoutingManager::PublishLocalOmrPrefix(void)
     else
     {
         Get<NetworkData::Notifier>().HandleServerDataUpdated();
-        otLogInfoBr("Published local OMR prefix %s in Thread network", mLocalOmrPrefix.ToString().AsCString());
+        otLogInfoBr("Publishing local OMR prefix %s in Thread network", mLocalOmrPrefix.ToString().AsCString());
     }
 
     return error;
@@ -444,7 +504,7 @@ void RoutingManager::UnpublishLocalOmrPrefix(void)
     SuccessOrExit(error = Get<NetworkData::Local>().RemoveOnMeshPrefix(mLocalOmrPrefix));
 
     Get<NetworkData::Notifier>().HandleServerDataUpdated();
-    otLogInfoBr("Unpublished local OMR prefix %s from Thread network", mLocalOmrPrefix.ToString().AsCString());
+    otLogInfoBr("Unpublishing local OMR prefix %s from Thread network", mLocalOmrPrefix.ToString().AsCString());
 
 exit:
     if (error != kErrorNone)
@@ -454,7 +514,7 @@ exit:
     }
 }
 
-Error RoutingManager::AddExternalRoute(const Ip6::Prefix &aPrefix, RoutePreference aRoutePreference)
+Error RoutingManager::AddExternalRoute(const Ip6::Prefix &aPrefix, RoutePreference aRoutePreference, bool aNat64)
 {
     Error                            error;
     NetworkData::ExternalRouteConfig routeConfig;
@@ -464,6 +524,7 @@ Error RoutingManager::AddExternalRoute(const Ip6::Prefix &aPrefix, RoutePreferen
     routeConfig.Clear();
     routeConfig.SetPrefix(aPrefix);
     routeConfig.mStable     = true;
+    routeConfig.mNat64      = aNat64;
     routeConfig.mPreference = aRoutePreference;
 
     error = Get<NetworkData::Local>().AddHasRoutePrefix(routeConfig);
@@ -474,7 +535,7 @@ Error RoutingManager::AddExternalRoute(const Ip6::Prefix &aPrefix, RoutePreferen
     else
     {
         Get<NetworkData::Notifier>().HandleServerDataUpdated();
-        otLogInfoBr("Added external route %s", aPrefix.ToString().AsCString());
+        otLogInfoBr("Adding external route %s", aPrefix.ToString().AsCString());
     }
 
     return error;
@@ -489,7 +550,7 @@ void RoutingManager::RemoveExternalRoute(const Ip6::Prefix &aPrefix)
     SuccessOrExit(error = Get<NetworkData::Local>().RemoveHasRoutePrefix(aPrefix));
 
     Get<NetworkData::Notifier>().HandleServerDataUpdated();
-    otLogInfoBr("Removed external route %s", aPrefix.ToString().AsCString());
+    otLogInfoBr("Removing external route %s", aPrefix.ToString().AsCString());
 
 exit:
     if (error != kErrorNone)
@@ -573,6 +634,36 @@ void RoutingManager::DeprecateOnLinkPrefix(void)
                                         TimeMilli::SecToMsec(kDefaultOnLinkPrefixLifetime));
 }
 
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+void RoutingManager::EvaluateNat64Prefix(void)
+{
+    OT_ASSERT(mIsRunning);
+
+    NetworkData::Iterator            iterator = NetworkData::kIteratorInit;
+    NetworkData::ExternalRouteConfig config;
+    bool                             hasAdvertisedNat64Prefix = false;
+
+    otLogInfoBr("Evaluating NAT64 prefix");
+
+    while (Get<NetworkData::Leader>().GetNextExternalRoute(iterator, config) == kErrorNone)
+    {
+        if (config.mNat64 && config.GetPrefix().IsValidNat64())
+        {
+            hasAdvertisedNat64Prefix = true;
+        }
+    }
+
+    if (!hasAdvertisedNat64Prefix && !mIsAdvertisingLocalNat64Prefix)
+    {
+        // TODO: when multiple prefixes exits, remove the ones with lower preference or numerically larger.
+        if (AddExternalRoute(mLocalNat64Prefix, NetworkData::kRoutePreferenceLow, /* aNat64= */ true) == kErrorNone)
+        {
+            mIsAdvertisingLocalNat64Prefix = true;
+        }
+    }
+}
+#endif
+
 // This method evaluate the routing policy depends on prefix and route
 // information on Thread Network and infra link. As a result, this
 // method May send RA messages on infra link and publish/unpublish
@@ -589,6 +680,9 @@ void RoutingManager::EvaluateRoutingPolicy(void)
     // 0. Evaluate on-link & OMR prefixes.
     newOnLinkPrefix = EvaluateOnLinkPrefix();
     EvaluateOmrPrefix(newOmrPrefixes);
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+    EvaluateNat64Prefix();
+#endif
 
     // 1. Send Router Advertisement message if necessary.
     SendRouterAdvertisement(newOmrPrefixes, newOnLinkPrefix);

src/core/border_router/routing_manager.hpp

@@ -138,6 +138,22 @@ public:
      */
     Error GetOnLinkPrefix(Ip6::Prefix &aPrefix);
 
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+    /**
+     * This method returns the local NAT64 prefix.
+     *
+     * The local NAT64 prefix will be published in the Thread network
+     * if none exists.
+     *
+     * @param[out]  aPrefix  A reference to where the prefix will be output to.
+     *
+     * @retval  kErrorInvalidState  The Border Routing Manager is not initialized yet.
+     * @retval  kErrorNone          Successfully retrieved the NAT64 prefix.
+     *
+     */
+    Error GetNat64Prefix(Ip6::Prefix &aPrefix);
+#endif // OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+
     /**
      * This method receives an ICMPv6 message on the infrastructure interface.
      *
@@ -278,13 +294,18 @@ private:
 
     const Ip6::Prefix *EvaluateOnLinkPrefix(void);
 
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+    Error LoadOrGenerateRandomNat64Prefix(void);
+    void  EvaluateNat64Prefix(void);
+#endif
+
     void  EvaluateRoutingPolicy(void);
     void  StartRoutingPolicyEvaluationJitter(uint32_t aJitterMilli);
     void  StartRoutingPolicyEvaluationDelay(uint32_t aDelayMilli);
     void  EvaluateOmrPrefix(OmrPrefixArray &aNewOmrPrefixes);
     Error PublishLocalOmrPrefix(void);
     void  UnpublishLocalOmrPrefix(void);
-    Error AddExternalRoute(const Ip6::Prefix &aPrefix, RoutePreference aRoutePreference);
+    Error AddExternalRoute(const Ip6::Prefix &aPrefix, RoutePreference aRoutePreference, bool aNat64 = false);
     void  RemoveExternalRoute(const Ip6::Prefix &aPrefix);
     void  StartRouterSolicitationDelay(void);
     Error SendRouterSolicitation(void);
@@ -359,6 +380,13 @@ private:
     TimeMilli  mTimeAdvertisedOnLinkPrefix;
     TimerMilli mOnLinkPrefixDeprecateTimer;
 
+    // The NAT64 prefix loaded from local persistent storage or
+    // randomly generated if none is found in persistent storage.
+    Ip6::Prefix mLocalNat64Prefix;
+
+    // True if the local NAT64 prefix is advertised in Thread network.
+    bool mIsAdvertisingLocalNat64Prefix;
+
     // The array of prefixes discovered on the infra link. Those
     // prefixes consist of on-link prefix(es) and OMR prefixes
     // advertised by BRs in another Thread Network which is connected to

src/core/common/settings.cpp

@@ -154,6 +154,7 @@ const char *SettingsBase::KeyToString(Key aKey)
         "SrpEcdsaKey",       // (11) kKeySrpEcdsaKey
         "SrpClientInfo",     // (12) kKeySrpClientInfo
         "SrpServerInfo",     // (13) kKeySrpServerInfo
+        "Nat64Prefix",       // (14) kKeyNat64Prefix
     };
 
     static_assert(1 == kKeyActiveDataset, "kKeyActiveDataset value is incorrect");
@@ -169,8 +170,9 @@ const char *SettingsBase::KeyToString(Key aKey)
     static_assert(11 == kKeySrpEcdsaKey, "kKeySrpEcdsaKey value is incorrect");
     static_assert(12 == kKeySrpClientInfo, "kKeySrpClientInfo value is incorrect");
     static_assert(13 == kKeySrpServerInfo, "kKeySrpServerInfo value is incorrect");
+    static_assert(14 == kKeyNat64Prefix, "kKeyNat64Prefix value is incorrect");
 
-    static_assert(kLastKey == kKeySrpServerInfo, "kLastKey is not valid");
+    static_assert(kLastKey == kKeyNat64Prefix, "kLastKey is not valid");
 
     OT_ASSERT(aKey <= kLastKey);
 
@@ -431,6 +433,7 @@ void Settings::Log(Action aAction, Error aError, Key aKey, const void *aValue)
 #if OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE
         case kKeyOmrPrefix:
         case kKeyOnLinkPrefix:
+        case kKeyNat64Prefix:
             LogPrefix(aAction, aKey, *reinterpret_cast<const Ip6::Prefix *>(aValue));
             break;
 #endif

src/core/common/settings.hpp

@@ -122,9 +122,10 @@ public:
         kKeySrpEcdsaKey       = OT_SETTINGS_KEY_SRP_ECDSA_KEY,
         kKeySrpClientInfo     = OT_SETTINGS_KEY_SRP_CLIENT_INFO,
         kKeySrpServerInfo     = OT_SETTINGS_KEY_SRP_SERVER_INFO,
+        kKeyNat64Prefix       = OT_SETTINGS_KEY_NAT64_PREFIX,
     };
 
-    static constexpr Key kLastKey = kKeySrpServerInfo; ///< The last (numerically) enumerator value in `Key`.
+    static constexpr Key kLastKey = kKeyNat64Prefix; ///< The last (numerically) enumerator value in `Key`.
 
     /**
      * This structure represents the device's own network information for settings storage.
@@ -596,6 +597,23 @@ public:
     private:
         OnLinkPrefix(void) = default;
     };
+
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+    /**
+     * This class defines constants and types for NAT64 prefix settings.
+     *
+     */
+    class Nat64Prefix
+    {
+    public:
+        static constexpr Key kKey = kKeyNat64Prefix; ///< The associated key.
+
+        typedef Ip6::Prefix ValueType; ///< The associated value type.
+
+    private:
+        Nat64Prefix(void) = default;
+    };
+#endif // OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
 #endif // OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE
 
 #if OPENTHREAD_CONFIG_SRP_CLIENT_ENABLE
@@ -848,7 +866,7 @@ public:
      *  - It must provide a nested type `EntryType::ValueType` to specify the associated entry value type.
      *
      * This version of `Read<EntryType>` is intended for use with entries that have a simple entry value type (which can
-     * be represented by an existing type), e.g., `OmrPrefx` (using `Ip6::Prefix` as the value type).
+     * be represented by an existing type), e.g., `OmrPrefix` (using `Ip6::Prefix` as the value type).
      *
      * @tparam EntryType              The settings entry type.
      *
@@ -898,7 +916,7 @@ public:
      *  - It must provide a nested type `EntryType::ValueType` to specify the associated entry value type.
      *
      * This version of `Save<EntryType>` is intended for use with entries that have a simple entry value type (which can
-     * be represented by an existing type), e.g., `OmrPrefx` (using `Ip6::Prefix` as the value type).
+     * be represented by an existing type), e.g., `OmrPrefix` (using `Ip6::Prefix` as the value type).
      *
      * @tparam EntryType              The settings entry type.
      *

src/core/config/border_router.h

@@ -75,6 +75,16 @@
 #define OPENTHREAD_CONFIG_BORDER_ROUTING_VICARIOUS_RS_ENABLE 1
 #endif
 
+/**
+ * @def OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+ *
+ * Define to 1 to enable Border Routing NAT64 support.
+ *
+ */
+#ifndef OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE
+#define OPENTHREAD_CONFIG_BORDER_ROUTING_NAT64_ENABLE 0
+#endif
+
 /**
  * @def OPENTHREAD_CONFIG_BORDER_AGENT_UDP_PORT
  *