[mle] implement alternate RLOC16 usage during role transition (#10006)

This commit introduces a mechanism for a device transitioning from
child to router role to keep receiving frames addressed to its
previous short address for a brief period.

A new radio platform API, `otPlatRadioSetAlternateShortAddress()`, is
introduced. This allows the OT stack to configure an alternate short
address. Radio platform support for this function is indicated by the
`OT_RADIO_CAPS_ALT_SHORT_ADDR` capability in `otPlatRadioGetCaps()`
The same function can be used with `OT_RADIO_INVALID_SHORT_ADDR`
(`0xfffe`) to clear a previously set alternate short address. Support
for the new API is implemented in RCP and `RadioSpinel`, ensuring
backward compatibility by dynamically checking supported radio
capabilities.

MLE code is updated to instruct the radio to use the old child RLOC16
as an alternate address upon role transition. The MLE layer will
automatically clear the alternate address after eight seconds, or if
other state/mode changes occur. This eight-second window ensures the
new router can transmit four MLE Advertisement messages.

examples/platforms/simulation/radio.c

@@ -382,6 +382,15 @@ void otPlatRadioSetShortAddress(otInstance *aInstance, otShortAddress aShortAddr
     sRadioContext.mShortAddress = aShortAddress;
 }
 
+void otPlatRadioSetAlternateShortAddress(otInstance *aInstance, otShortAddress aShortAddress)
+{
+    OT_UNUSED_VARIABLE(aInstance);
+
+    assert(aInstance != NULL);
+
+    sRadioContext.mAlternateShortAddress = aShortAddress;
+}
+
 void otPlatRadioSetPromiscuous(otInstance *aInstance, bool aEnable)
 {
     OT_UNUSED_VARIABLE(aInstance);
@@ -849,9 +858,9 @@ void radioProcessFrame(otInstance *aInstance)
 
     otEXPECT(sPromiscuous == false);
 
-    otEXPECT_ACTION(
-        otMacFrameDoesAddrMatch(&sReceiveFrame, sPanid, sRadioContext.mShortAddress, &sRadioContext.mExtAddress),
-        error = OT_ERROR_ABORT);
+    otEXPECT_ACTION(otMacFrameDoesAddrMatchAny(&sReceiveFrame, sPanid, sRadioContext.mShortAddress,
+                                               sRadioContext.mAlternateShortAddress, &sRadioContext.mExtAddress),
+                    error = OT_ERROR_ABORT);
 
 #if OPENTHREAD_CONFIG_MLE_LINK_METRICS_SUBJECT_ENABLE
     otEXPECT_ACTION(otMacFrameGetSrcAddr(&sReceiveFrame, &macAddress) == OT_ERROR_NONE, error = OT_ERROR_PARSE);

examples/platforms/utils/mac_frame.cpp

@@ -41,6 +41,15 @@ bool otMacFrameDoesAddrMatch(const otRadioFrame *aFrame,
                              otPanId             aPanId,
                              otShortAddress      aShortAddress,
                              const otExtAddress *aExtAddress)
+{
+    return otMacFrameDoesAddrMatchAny(aFrame, aPanId, aShortAddress, Mac::kShortAddrInvalid, aExtAddress);
+}
+
+bool otMacFrameDoesAddrMatchAny(const otRadioFrame *aFrame,
+                                otPanId             aPanId,
+                                otShortAddress      aShortAddress,
+                                otShortAddress      aAltShortAddress,
+                                const otExtAddress *aExtAddress)
 {
     const Mac::Frame &frame = *static_cast<const Mac::Frame *>(aFrame);
     bool              rval  = true;
@@ -52,7 +61,9 @@ bool otMacFrameDoesAddrMatch(const otRadioFrame *aFrame,
     switch (dst.GetType())
     {
     case Mac::Address::kTypeShort:
-        VerifyOrExit(dst.GetShort() == Mac::kShortAddrBroadcast || dst.GetShort() == aShortAddress, rval = false);
+        VerifyOrExit(dst.GetShort() == Mac::kShortAddrBroadcast || dst.GetShort() == aShortAddress ||
+                         (aAltShortAddress != Mac::kShortAddrInvalid && dst.GetShort() == aAltShortAddress),
+                     rval = false);
         break;
 
     case Mac::Address::kTypeExtended:

examples/platforms/utils/mac_frame.h

@@ -132,6 +132,25 @@ bool otMacFrameDoesAddrMatch(const otRadioFrame *aFrame,
                              otShortAddress      aShortAddress,
                              const otExtAddress *aExtAddress);
 
+/**
+ * Check if @p aFrame matches the @p aPandId and @p aShortAddress, or @p aAltShortAddress or @p aExtAddress.
+ *
+ * @param[in]   aFrame            A pointer to the frame.
+ * @param[in]   aPanId            The PAN id to match with.
+ * @param[in]   aShortAddress     The short address to match with.
+ * @param[in]   aAltShortAddress  The alternate short address to match with. Can be `OT_RADIO_INVALID_SHORT_ADDR` if
+ *                                there is no alternate address.
+ * @param[in]   aExtAddress       The extended address to match with.
+ *
+ * @retval  true    It is a broadcast or matches with the PAN id and one of the addresses.
+ * @retval  false   It doesn't match.
+ */
+bool otMacFrameDoesAddrMatchAny(const otRadioFrame *aFrame,
+                                otPanId             aPanId,
+                                otShortAddress      aShortAddress,
+                                otShortAddress      aAltShortAddress,
+                                const otExtAddress *aExtAddress);
+
 /**
  * Get source MAC address.
  *
@@ -319,6 +338,7 @@ typedef struct otRadioContext
     uint32_t         mCslSampleTime; ///< The sample time based on the microsecond timer.
     uint16_t         mCslPeriod;     ///< In unit of 10 symbols.
     otShortAddress   mShortAddress;
+    otShortAddress   mAlternateShortAddress;
     otRadioKeyType   mKeyType;
     uint8_t          mKeyId;
     otMacKeyMaterial mPrevKey;