[radio] fix alternate short address initialization and matching (#13700)

When a router-eligible Child transitions to Router (e.g. during
TestCoapObserve when Leader notifies an upgraded child at its former
child RLOC16), OpenThread calls otPlatRadioSetAlternateShortAddress(),
which stores the previous short address in mRadioContext.mAlternateShortAddress.

Fix alternate short address handling consistently across Nexus,
simulation radio, and MAC frame utils:
- Advertise OT_RADIO_CAPS_ALT_SHORT_ADDR in both Nexus otPlatRadioGetCaps()
  and simulation gRadioCaps.
- Initialize mCslShortAddress, mShortAddress, and mAlternateShortAddress
  in otRadioContext to OT_RADIO_INVALID_SHORT_ADDR in both
  Nexus::Radio::Reset() and simulation platformRadioInit().
- Drop duplicate Radio::mShortAddress and Radio::mExtAddress from
  Nexus::Radio and use mRadioContext consistently.
- Simplify Nexus::Radio::Radio(void) to call Reset().
- Guard against Mac::kShortAddrInvalid and match both short addresses in
  Nexus::Radio::Matches() and otMacFrameDoesAddrMatchAny().

examples/platforms/simulation/radio.c

@@ -144,9 +144,9 @@ static bool sRadioCoexEnabled = true;
 
 otRadioCaps gRadioCaps =
 #if OPENTHREAD_CONFIG_THREAD_VERSION >= OT_THREAD_VERSION_1_2
-    OT_RADIO_CAPS_TRANSMIT_SEC;
+    OT_RADIO_CAPS_ALT_SHORT_ADDR | OT_RADIO_CAPS_TRANSMIT_SEC;
 #else
-    OT_RADIO_CAPS_NONE;
+    OT_RADIO_CAPS_ALT_SHORT_ADDR;
 #endif
 
 static otRadioContext sRadioContext;
@@ -417,6 +417,10 @@ void platformRadioInit(void)
     sTransmitFrame.mPsdu = sTransmitMessage.mPsdu;
     sAckFrame.mPsdu      = sAckMessage.mPsdu;
 
+    sRadioContext.mCslShortAddress       = OT_RADIO_INVALID_SHORT_ADDR;
+    sRadioContext.mShortAddress          = OT_RADIO_INVALID_SHORT_ADDR;
+    sRadioContext.mAlternateShortAddress = OT_RADIO_INVALID_SHORT_ADDR;
+
 #if OPENTHREAD_CONFIG_MAC_HEADER_IE_SUPPORT
     sTransmitFrame.mInfo.mTxInfo.mIeInfo = &sTransmitIeInfo;
 #else

examples/platforms/utils/mac_frame.cpp

@@ -108,12 +108,14 @@ bool otMacFrameDoesAddrMatchAny(const otRadioFrame *aFrame,
     switch (frameInfo.mAddrs.mDestination.GetType())
     {
     case Mac::Address::kTypeShort:
-        VerifyOrExit(frameInfo.mAddrs.mDestination.GetShort() == Mac::kShortAddrBroadcast ||
-                         frameInfo.mAddrs.mDestination.GetShort() == aShortAddress ||
-                         (aAltShortAddress != Mac::kShortAddrInvalid &&
-                          frameInfo.mAddrs.mDestination.GetShort() == aAltShortAddress),
+    {
+        Mac::ShortAddress dstAddr = frameInfo.mAddrs.mDestination.GetShort();
+
+        VerifyOrExit(dstAddr != Mac::kShortAddrInvalid, rval = false);
+        VerifyOrExit(dstAddr == Mac::kShortAddrBroadcast || dstAddr == aShortAddress || dstAddr == aAltShortAddress,
                      rval = false);
         break;
+    }
 
     case Mac::Address::kTypeExtended:
         VerifyOrExit(frameInfo.mAddrs.mDestination.GetExtended() == *static_cast<const Mac::ExtAddress *>(aExtAddress),

tests/nexus/platform/nexus_radio.cpp

@@ -42,7 +42,7 @@ extern "C" {
 otRadioCaps otPlatRadioGetCaps(otInstance *aInstance)
 {
     OT_UNUSED_VARIABLE(aInstance);
-    return OT_RADIO_CAPS_TRANSMIT_SEC;
+    return OT_RADIO_CAPS_TRANSMIT_SEC | OT_RADIO_CAPS_ALT_SHORT_ADDR;
 }
 
 int8_t otPlatRadioGetReceiveSensitivity(otInstance *aInstance)
@@ -65,18 +65,13 @@ void otPlatRadioSetPanId(otInstance *aInstance, otPanId aPanId) { AsNode(aInstan
 
 void otPlatRadioSetExtendedAddress(otInstance *aInstance, const otExtAddress *aExtAddress)
 {
-    Radio &radio = AsNode(aInstance).mRadio;
-
-    radio.mExtAddress.Set(aExtAddress->m8, Mac::ExtAddress::kReverseByteOrder);
-    AsCoreType(&radio.mRadioContext.mExtAddress).Set(aExtAddress->m8, Mac::ExtAddress::kReverseByteOrder);
+    AsCoreType(&AsNode(aInstance).mRadio.mRadioContext.mExtAddress)
+        .Set(aExtAddress->m8, Mac::ExtAddress::kReverseByteOrder);
 }
 
 void otPlatRadioSetShortAddress(otInstance *aInstance, otShortAddress aShortAddress)
 {
-    Radio &radio = AsNode(aInstance).mRadio;
-
-    radio.mShortAddress               = aShortAddress;
-    radio.mRadioContext.mShortAddress = aShortAddress;
+    AsNode(aInstance).mRadio.mRadioContext.mShortAddress = aShortAddress;
 }
 
 void otPlatRadioSetAlternateShortAddress(otInstance *aInstance, otShortAddress aShortAddress)
@@ -362,19 +357,7 @@ otError otPlatRadioConfigureEnhAckProbing(otInstance         *aInstance,
 //---------------------------------------------------------------------------------------------------------------------
 // Radio
 
-Radio::Radio(void)
-    : mState(kStateDisabled)
-    , mPromiscuous(false)
-    , mSrcMatchEnabled(false)
-    , mMacFrameCounterReset(false)
-    , mChannel(0)
-    , mPanId(0)
-    , mShortAddress(Mac::kShortAddrInvalid)
-{
-    mExtAddress.Clear();
-    ClearAllBytes(mRadioContext);
-    mTxFrame.mInfo.mTxInfo.mIeInfo = &mTxIeInfo;
-}
+Radio::Radio(void) { Reset(); }
 
 void Radio::Reset(void)
 {
@@ -384,13 +367,14 @@ void Radio::Reset(void)
     mMacFrameCounterReset = false;
     mChannel              = 0;
     mPanId                = 0;
-    mShortAddress         = Mac::kShortAddrInvalid;
-    mExtAddress.Clear();
     mSrcMatchShortEntries.Clear();
     mSrcMatchExtEntries.Clear();
     mLinkMetricsEntries.Clear();
     ClearAllBytes(mRadioContext);
-    mTxFrame.mInfo.mTxInfo.mIeInfo = &mTxIeInfo;
+    mRadioContext.mCslShortAddress       = Mac::kShortAddrInvalid;
+    mRadioContext.mShortAddress          = Mac::kShortAddrInvalid;
+    mRadioContext.mAlternateShortAddress = Mac::kShortAddrInvalid;
+    mTxFrame.mInfo.mTxInfo.mIeInfo       = &mTxIeInfo;
 }
 
 Error Radio::ConfigureEnhAckProbing(Mac::ShortAddress      aShortAddress,
@@ -506,11 +490,15 @@ bool Radio::Matches(const Mac::Address &aAddress, Mac::PanId aPanId) const
 
     if (aAddress.IsShort())
     {
-        VerifyOrExit(aAddress.IsBroadcast() || aAddress.GetShort() == mShortAddress);
+        Mac::ShortAddress shortAddr = aAddress.GetShort();
+
+        VerifyOrExit(shortAddr != Mac::kShortAddrInvalid);
+        VerifyOrExit(aAddress.IsBroadcast() || (shortAddr == mRadioContext.mShortAddress) ||
+                     (shortAddr == mRadioContext.mAlternateShortAddress));
     }
     else if (aAddress.IsExtended())
     {
-        VerifyOrExit(aAddress.GetExtended() == mExtAddress);
+        VerifyOrExit(aAddress.GetExtended() == AsCoreType(&mRadioContext.mExtAddress));
     }
 
     if ((aPanId != Mac::kPanIdBroadcast) && (mPanId != Mac::kPanIdBroadcast))

tests/nexus/platform/nexus_radio.hpp

@@ -96,8 +96,6 @@ struct Radio
     bool                                    mMacFrameCounterReset : 1;
     uint8_t                                 mChannel;
     Mac::PanId                              mPanId;
-    Mac::ShortAddress                       mShortAddress;
-    Mac::ExtAddress                         mExtAddress;
     Frame                                   mTxFrame;
     otRadioIeInfo                           mTxIeInfo;
     otRadioContext                          mRadioContext;