[mle] update DetachGracefully() to stop BR routing manager (#8105)

This commit updates `Mle::DetachGracefully()` to stop Border Router
`RoutingManager`. This ensures that BR will have the chance to send
a final Router Advertisement message desecrating/removing its
previously advertised on-link or route prefixes.

src/core/border_router/routing_manager.hpp

@@ -119,6 +119,21 @@ public:
      */
     Error SetEnabled(bool aEnabled);
 
+    /**
+     * This method requests the Border Routing Manager to stop.
+     *
+     * If Border Routing Manager is running, calling this method immediately stops it and triggers the preparation
+     * and sending of a final Router Advertisement (RA) message on infrastructure interface which deprecates and/or
+     * removes any previously advertised PIO/RIO prefixes. If Routing Manager is not running (or not enabled), no
+     * action is taken.
+     *
+     * Note that this method does not change whether the Routing Manager is enabled or disabled (see `SetEnabled()`).
+     * It stops the Routing Manager temporarily. After calling this method if the device role gets changes (device
+     * gets attached) and/or the infra interface state gets changed, the Routing Manager may be started again.
+     *
+     */
+    void RequestStop(void) { Stop(); }
+
     /**
      * This method gets the preference used when advertising Route Info Options (e.g., for discovered OMR prefixes) in
      * Router Advertisement messages sent over the infrastructure link.

src/core/thread/mle.cpp

@@ -4295,7 +4295,8 @@ uint64_t Mle::CalcParentCslMetric(const Mac::CslAccuracy &aCslAccuracy)
 
 Error Mle::DetachGracefully(otDetachGracefullyCallback aCallback, void *aContext)
 {
-    Error error = kErrorNone;
+    Error    error   = kErrorNone;
+    uint32_t timeout = kDetachGracefullyTimeout;
 
     VerifyOrExit(!IsDetachingGracefully(), error = kErrorBusy);
 
@@ -4304,27 +4305,36 @@ Error Mle::DetachGracefully(otDetachGracefullyCallback aCallback, void *aContext
     mDetachGracefullyCallback = aCallback;
     mDetachGracefullyContext  = aContext;
 
-    if (IsChild() || IsRouter())
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE
+    Get<BorderRouter::RoutingManager>().RequestStop();
+#endif
+
+    switch (mRole)
     {
-        mDetachGracefullyTimer.Start(kDetachGracefullyTimeout);
-    }
-    else
-    {
-        // If the device is a leader, or it's already detached or disabled, we start the timer with zero duration to
-        // stop and invoke the callback when the timer fires, so the operation finishes immediately and asynchronously.
-        mDetachGracefullyTimer.Start(0);
+    case kRoleLeader:
+        break;
+
+    case kRoleRouter:
+#if OPENTHREAD_FTD
+        Get<MleRouter>().SendAddressRelease();
+#endif
+        break;
+
+    case kRoleChild:
+        IgnoreError(SendChildUpdateRequest(/* aAppendChallenge */ false, /* aTimeout */ 0));
+        break;
+
+    case kRoleDisabled:
+    case kRoleDetached:
+        // If device is already detached or disabled, we start the timer
+        // with zero duration to stop and invoke the callback when the
+        // timer fires, so the operation finishes immediately and
+        // asynchronously.
+        timeout = 0;
+        break;
     }
 
-    if (IsChild())
-    {
-        IgnoreError(SendChildUpdateRequest(/* aAppendChallenge */ false, /* aTimeout */ 0));
-    }
-#if OPENTHREAD_FTD
-    else if (IsRouter())
-    {
-        Get<MleRouter>().SendAddressRelease(&Mle::HandleDetachGracefullyAddressReleaseResponse, this);
-    }
-#endif
+    mDetachGracefullyTimer.Start(timeout);
 
 exit:
     return error;
@@ -4340,28 +4350,6 @@ void Mle::HandleDetachGracefullyTimer(void)
     Stop();
 }
 
-#if OPENTHREAD_FTD
-void Mle::HandleDetachGracefullyAddressReleaseResponse(void *               aContext,
-                                                       otMessage *          aMessage,
-                                                       const otMessageInfo *aMessageInfo,
-                                                       Error                aResult)
-{
-    OT_UNUSED_VARIABLE(aMessage);
-    OT_UNUSED_VARIABLE(aMessageInfo);
-    OT_UNUSED_VARIABLE(aResult);
-
-    static_cast<MleRouter *>(aContext)->HandleDetachGracefullyAddressReleaseResponse();
-}
-
-void Mle::HandleDetachGracefullyAddressReleaseResponse(void)
-{
-    if (IsDetachingGracefully())
-    {
-        Stop();
-    }
-}
-#endif // OPENTHREAD_FTD
-
 //---------------------------------------------------------------------------------------------------------------------
 // TlvList
 

src/core/thread/mle_router.cpp

@@ -3760,7 +3760,7 @@ exit:
     return error;
 }
 
-void MleRouter::SendAddressRelease(Coap::ResponseHandler aResponseHandler, void *aResponseHandlerContext)
+void MleRouter::SendAddressRelease(void)
 {
     Error            error = kErrorNone;
     Tmf::MessageInfo messageInfo(GetInstance());
@@ -3774,8 +3774,7 @@ void MleRouter::SendAddressRelease(Coap::ResponseHandler aResponseHandler, void
 
     SuccessOrExit(error = messageInfo.SetSockAddrToRlocPeerAddrToLeaderRloc());
 
-    SuccessOrExit(error =
-                      Get<Tmf::Agent>().SendMessage(*message, messageInfo, aResponseHandler, aResponseHandlerContext));
+    SuccessOrExit(error = Get<Tmf::Agent>().SendMessage(*message, messageInfo));
 
     Log(kMessageSend, kTypeAddressRelease, messageInfo.GetPeerAddr());
 

src/core/thread/mle_router.hpp

@@ -570,15 +570,6 @@ public:
     void SetThreadVersionCheckEnabled(bool aEnabled) { mThreadVersionCheckEnabled = aEnabled; }
 #endif
 
-    /**
-     * This function sends an Address Release.
-     *
-     * @param[in] aResponseHandler        A pointer to a function that is called upon response reception or time-out.
-     * @param[in] aResponseHandlerContext A pointer to callback application-specific context.
-     *
-     */
-    void SendAddressRelease(Coap::ResponseHandler aResponseHandler = nullptr, void *aResponseHandlerContext = nullptr);
-
 private:
     static constexpr uint16_t kDiscoveryMaxJitter            = 250;  // Max jitter delay Discovery Responses (in msec).
     static constexpr uint32_t kStateUpdatePeriod             = 1000; // State update period (in msec).
@@ -615,6 +606,7 @@ private:
                                      ThreadStatusTlv::Status aResponseStatus,
                                      const Router *          aRouter,
                                      const Ip6::MessageInfo &aMessageInfo);
+    void  SendAddressRelease(void);
     void  SendAdvertisement(void);
     Error SendLinkAccept(const Ip6::MessageInfo &aMessageInfo,
                          Neighbor *              aNeighbor,