[routing-manager] track and report last update time of routers (#10244)

This commit enhances the `DiscoveredPrefixTable::Router` class to
track the last time an ND6 message (RA or NS) was received from each
discovered router. This information is now available through the
`otBorderRoutingRouterEntry` and can be viewed using the `br routers`
CLI command.

include/openthread/border_routing.h

@@ -97,6 +97,7 @@ typedef struct otBorderRoutingPrefixTableIterator
 typedef struct otBorderRoutingRouterEntry
 {
     otIp6Address mAddress;                      ///< IPv6 address of the router.
+    uint32_t     mMsecSinceLastUpdate;          ///< Milliseconds since last update (any message rx) from this router.
     bool         mManagedAddressConfigFlag : 1; ///< The router's Managed Address Config flag (`M` flag).
     bool         mOtherConfigFlag : 1;          ///< The router's Other Config flag (`O` flag).
     bool         mStubRouterFlag : 1;           ///< The router's Stub Router flag.

include/openthread/instance.h

@@ -53,7 +53,7 @@ extern "C" {
  * @note This number versions both OpenThread platform and user APIs.
  *
  */
-#define OPENTHREAD_API_VERSION (413)
+#define OPENTHREAD_API_VERSION (414)
 
 /**
  * @addtogroup api-instance

src/cli/README_BR.md

@@ -351,9 +351,10 @@ Info per router:
   - M: Managed Address Config flag
   - O: Other Config flag
   - Stub: Stub Router flag (indicates whether the router is a stub router)
+- Milliseconds since last received message from this router
 
 ```bash
 > br routers
-ff02:0:0:0:0:0:0:1 (M:0 O:0 Stub:1)
+ff02:0:0:0:0:0:0:1 (M:0 O:0 Stub:1) ms-since-rx:1505
 Done
 ```

src/cli/cli_br.cpp

@@ -428,7 +428,7 @@ template <> otError Br::Process<Cmd("prefixtable")>(Arg aArgs[])
         }
 
         OutputFormat("router:");
-        OutputRouterInfo(entry.mRouter);
+        OutputRouterInfo(entry.mRouter, kShortVersion);
     }
 
 exit:
@@ -518,7 +518,7 @@ exit:
  * @cli br routers
  * @code
  * br routers
- * ff02:0:0:0:0:0:0:1 (M:0 O:0 Stub:1)
+ * ff02:0:0:0:0:0:0:1 (M:0 O:0 Stub:1) ms-since-rx:1505
  * Done
  * @endcode
  * @par
@@ -529,6 +529,7 @@ exit:
  *   - M: Managed Address Config flag
  *   - O: Other Config flag
  *   - Stub: Stub Router flag (indicates whether the router is a stub router)
+ * - Milliseconds since last received message from this router
  * @sa otBorderRoutingGetNextRouterEntry
  */
 template <> otError Br::Process<Cmd("routers")>(Arg aArgs[])
@@ -543,18 +544,29 @@ template <> otError Br::Process<Cmd("routers")>(Arg aArgs[])
 
     while (otBorderRoutingGetNextRouterEntry(GetInstancePtr(), &iterator, &entry) == OT_ERROR_NONE)
     {
-        OutputRouterInfo(entry);
+        OutputRouterInfo(entry, kLongVersion);
     }
 
 exit:
     return error;
 }
 
-void Br::OutputRouterInfo(const otBorderRoutingRouterEntry &aEntry)
+void Br::OutputRouterInfo(const otBorderRoutingRouterEntry &aEntry, RouterOutputMode aMode)
 {
     OutputIp6Address(aEntry.mAddress);
-    OutputLine(" (M:%u O:%u Stub:%u)", aEntry.mManagedAddressConfigFlag, aEntry.mOtherConfigFlag,
-               aEntry.mStubRouterFlag);
+    OutputFormat(" (M:%u O:%u Stub:%u)", aEntry.mManagedAddressConfigFlag, aEntry.mOtherConfigFlag,
+                 aEntry.mStubRouterFlag);
+
+    switch (aMode)
+    {
+    case kShortVersion:
+        OutputNewLine();
+        break;
+
+    case kLongVersion:
+        OutputLine(" ms-since-rx:%lu", ToUlong(aEntry.mMsecSinceLastUpdate));
+        break;
+    }
 }
 
 template <> otError Br::Process<Cmd("raoptions")>(Arg aArgs[])

src/cli/cli_br.hpp

@@ -89,10 +89,16 @@ private:
         kPrefixTypeFavored = 1u << 1,
     };
 
+    enum RouterOutputMode : uint8_t
+    {
+        kShortVersion,
+        kLongVersion,
+    };
+
     template <CommandId kCommandId> otError Process(Arg aArgs[]);
 
     otError ParsePrefixTypeArgs(Arg aArgs[], PrefixType &aFlags);
-    void    OutputRouterInfo(const otBorderRoutingRouterEntry &aEntry);
+    void    OutputRouterInfo(const otBorderRoutingRouterEntry &aEntry, RouterOutputMode aMode);
 };
 
 } // namespace Cli

src/core/border_router/routing_manager.cpp

@@ -1643,9 +1643,10 @@ exit:
 
 void RoutingManager::RxRaTracker::UpdateRouterOnRx(Router &aRouter)
 {
-    aRouter.mNsProbeCount = 0;
-    aRouter.mTimeout = TimerMilli::GetNow() + Random::NonCrypto::AddJitter(Router::kActiveTimeout, Router::kJitter);
+    aRouter.mNsProbeCount   = 0;
+    aRouter.mLastUpdateTime = TimerMilli::GetNow();
 
+    aRouter.mTimeout = aRouter.mLastUpdateTime + Random::NonCrypto::AddJitter(Router::kActiveTimeout, Router::kJitter);
     mRouterTimer.FireAtIfEarlier(aRouter.mTimeout);
 }
 
@@ -1770,7 +1771,7 @@ Error RoutingManager::RxRaTracker::GetNextEntry(PrefixTableIterator &aIterator,
 
     SuccessOrExit(error = iterator.AdvanceToNextEntry());
 
-    iterator.GetRouter()->CopyInfoTo(aEntry.mRouter);
+    iterator.GetRouter()->CopyInfoTo(aEntry.mRouter, iterator.GetInitTime());
 
     switch (iterator.GetEntryType())
     {
@@ -1794,7 +1795,7 @@ Error RoutingManager::RxRaTracker::GetNextRouter(PrefixTableIterator &aIterator,
     ClearAllBytes(aEntry);
 
     SuccessOrExit(error = iterator.AdvanceToNextRouter(Iterator::kRouterIterator));
-    iterator.GetRouter()->CopyInfoTo(aEntry);
+    iterator.GetRouter()->CopyInfoTo(aEntry, iterator.GetInitTime());
 
 exit:
     return error;
@@ -1917,9 +1918,10 @@ bool RoutingManager::RxRaTracker::Router::Matches(EmptyChecker aChecker) const
     return !hasFlags && mOnLinkPrefixes.IsEmpty() && mRoutePrefixes.IsEmpty();
 }
 
-void RoutingManager::RxRaTracker::Router::CopyInfoTo(RouterEntry &aEntry) const
+void RoutingManager::RxRaTracker::Router::CopyInfoTo(RouterEntry &aEntry, TimeMilli aNow) const
 {
     aEntry.mAddress                  = mAddress;
+    aEntry.mMsecSinceLastUpdate      = aNow - mLastUpdateTime;
     aEntry.mManagedAddressConfigFlag = mManagedAddressConfigFlag;
     aEntry.mOtherConfigFlag          = mOtherConfigFlag;
     aEntry.mStubRouterFlag           = mStubRouterFlag;

src/core/border_router/routing_manager.hpp

@@ -817,7 +817,7 @@ private:
 
             bool Matches(const Ip6::Address &aAddress) const { return aAddress == mAddress; }
             bool Matches(EmptyChecker aChecker) const;
-            void CopyInfoTo(RouterEntry &aEntry) const;
+            void CopyInfoTo(RouterEntry &aEntry, TimeMilli aNow) const;
 
             using OnLinkPrefixList = OwningList<Entry<OnLinkPrefix>>;
             using RoutePrefixList  = OwningList<Entry<RoutePrefix>>;
@@ -825,6 +825,7 @@ private:
             Ip6::Address     mAddress;
             OnLinkPrefixList mOnLinkPrefixes;
             RoutePrefixList  mRoutePrefixes;
+            TimeMilli        mLastUpdateTime;
             TimeMilli        mTimeout;
             uint8_t          mNsProbeCount;
             bool             mManagedAddressConfigFlag : 1;