[router-table] add new methods to help iterate over router entries (#3527)

src/core/thread/router_table.cpp

@@ -52,29 +52,12 @@ RouterTable::Iterator::Iterator(Instance &aInstance)
 
 void RouterTable::Iterator::Reset(void)
 {
-    RouterTable &routerTable = GetInstance().Get<RouterTable>();
+    mRouter = GetInstance().Get<RouterTable>().GetFirstEntry();
-
-    mRouter = &routerTable.mRouters[0];
-
-    if (mRouter->GetRloc16() == 0xffff)
-    {
-        mRouter = NULL;
-    }
 }
 
 void RouterTable::Iterator::Advance(void)
 {
-    RouterTable &routerTable = GetInstance().Get<RouterTable>();
+    mRouter = GetInstance().Get<RouterTable>().GetNextEntry(mRouter);
-    Router *     listEnd     = &routerTable.mRouters[Mle::kMaxRouters];
-
-    VerifyOrExit(mRouter != NULL);
-
-    mRouter++;
-
-    VerifyOrExit(mRouter < listEnd && mRouter->GetRloc16() != 0xffff, mRouter = NULL);
-
-exit:
-    return;
 }
 
 RouterTable::RouterTable(Instance &aInstance)
@@ -86,6 +69,26 @@ RouterTable::RouterTable(Instance &aInstance)
     Clear();
 }
 
+const Router *RouterTable::GetFirstEntry(void) const
+{
+    const Router *router = &mRouters[0];
+    VerifyOrExit(router->GetRloc16() != 0xffff, router = NULL);
+
+exit:
+    return router;
+}
+
+const Router *RouterTable::GetNextEntry(const Router *aRouter) const
+{
+    VerifyOrExit(aRouter != NULL);
+    aRouter++;
+    VerifyOrExit(aRouter < &mRouters[Mle::kMaxRouters], aRouter = NULL);
+    VerifyOrExit(aRouter->GetRloc16() != 0xffff, aRouter = NULL);
+
+exit:
+    return aRouter;
+}
+
 void RouterTable::Clear(void)
 {
     memset(mAllocatedRouterIds, 0, sizeof(mAllocatedRouterIds));
@@ -271,19 +274,12 @@ otError RouterTable::Release(uint8_t aRouterId)
 
     mRouterIdReuseDelay[aRouterId] = Mle::kRouterIdReuseDelay;
 
-    for (int i = 0; i < Mle::kMaxRouters; i++)
+    for (Router *router = GetFirstEntry(); router != NULL; router = GetNextEntry(router))
     {
-        Router &router = mRouters[i];
+        if (router->GetNextHop() == rloc16)
-
-        if (router.GetRloc16() == 0xffff)
         {
-            break;
+            router->SetNextHop(Mle::kInvalidRouterId);
-        }
+            router->SetCost(0);
-
-        if (router.GetNextHop() == rloc16)
-        {
-            router.SetNextHop(Mle::kInvalidRouterId);
-            router.SetCost(0);
         }
     }
 
@@ -307,21 +303,14 @@ void RouterTable::RemoveNeighbor(Router &aRouter)
     aRouter.SetLinkQualityOut(0);
     aRouter.SetLastHeard(TimerMilli::GetNow());
 
-    for (uint8_t i = 0; i < Mle::kMaxRouters; i++)
+    for (Router *cur = GetFirstEntry(); cur != NULL; cur = GetNextEntry(cur))
     {
-        Router &cur = mRouters[i];
+        if (cur->GetNextHop() == aRouter.GetRouterId())
-
-        if (cur.GetRloc16() == 0xffff)
         {
-            break;
+            cur->SetNextHop(Mle::kInvalidRouterId);
-        }
+            cur->SetCost(0);
 
-        if (cur.GetNextHop() == aRouter.GetRouterId())
+            if (GetLinkCost(*cur) >= Mle::kMaxRouteCost)
-        {
-            cur.SetNextHop(Mle::kInvalidRouterId);
-            cur.SetCost(0);
-
-            if (GetLinkCost(cur) >= Mle::kMaxRouteCost)
             {
                 netif.GetMle().ResetAdvertiseInterval();
             }
@@ -341,16 +330,9 @@ uint8_t RouterTable::GetActiveLinkCount(void) const
 {
     uint8_t activeLinks = 0;
 
-    for (int i = 0; i < Mle::kMaxRouters; i++)
+    for (const Router *router = GetFirstEntry(); router != NULL; router = GetNextEntry(router))
     {
-        const Router &cur = mRouters[i];
+        if (router->GetState() == Neighbor::kStateValid)
-
-        if (cur.GetRloc16() == 0xffff)
-        {
-            break;
-        }
-
-        if (cur.GetState() == Neighbor::kStateValid)
         {
             activeLinks++;
         }
@@ -365,11 +347,10 @@ Router *RouterTable::GetNeighbor(uint16_t aRloc16)
 
     VerifyOrExit(aRloc16 != GetNetif().GetMle().GetRloc16());
 
-    for (int i = 0; i < Mle::kMaxRouters; i++)
+    for (router = GetFirstEntry(); router != NULL; router = GetNextEntry(router))
     {
-        if (mRouters[i].GetState() == Neighbor::kStateValid && mRouters[i].GetRloc16() == aRloc16)
+        if (router->GetState() == Neighbor::kStateValid && router->GetRloc16() == aRloc16)
         {
-            router = &mRouters[i];
             ExitNow();
         }
     }
@@ -384,11 +365,10 @@ Router *RouterTable::GetNeighbor(const Mac::ExtAddress &aExtAddress)
 
     VerifyOrExit(aExtAddress != GetNetif().GetMac().GetExtAddress());
 
-    for (int i = 0; i < Mle::kMaxRouters; i++)
+    for (router = GetFirstEntry(); router != NULL; router = GetNextEntry(router))
     {
-        if (mRouters[i].GetState() == Neighbor::kStateValid && mRouters[i].GetExtAddress() == aExtAddress)
+        if (router->GetState() == Neighbor::kStateValid && router->GetExtAddress() == aExtAddress)
         {
-            router = &mRouters[i];
             ExitNow();
         }
     }
@@ -399,41 +379,32 @@ exit:
 
 const Router *RouterTable::GetRouter(uint8_t aRouterId) const
 {
-    const Router *rval   = NULL;
+    const Router *router = NULL;
     uint16_t      rloc16 = Mle::Mle::GetRloc16(aRouterId);
 
-    for (uint8_t i = 0; i < Mle::kMaxRouters; i++)
+    for (router = GetFirstEntry(); router != NULL; router = GetNextEntry(router))
     {
-        if (mRouters[i].GetRloc16() == rloc16)
+        if (router->GetRloc16() == rloc16)
         {
-            rval = &mRouters[i];
+            break;
-            ExitNow();
         }
     }
 
-exit:
+    return router;
-    return rval;
 }
 
 Router *RouterTable::GetRouter(const Mac::ExtAddress &aExtAddress)
 {
     Router *router = NULL;
 
-    for (int i = 0; i < Mle::kMaxRouters; i++)
+    for (router = GetFirstEntry(); router != NULL; router = GetNextEntry(router))
     {
-        if (mRouters[i].GetRloc16() == 0xffff)
+        if (router->GetExtAddress() == aExtAddress)
         {
             break;
         }
-
-        if (mRouters[i].GetExtAddress() == aExtAddress)
-        {
-            router = &mRouters[i];
-            ExitNow();
-        }
     }
 
-exit:
     return router;
 }
 
@@ -488,9 +459,9 @@ uint8_t RouterTable::GetNeighborCount(void) const
 {
     uint8_t count = 0;
 
-    for (int i = 0; i < Mle::kMaxRouters; i++)
+    for (const Router *router = GetFirstEntry(); router != NULL; router = GetNextEntry(router))
     {
-        if (mRouters[i].GetState() == Neighbor::kStateValid)
+        if (router->GetState() == Neighbor::kStateValid)
         {
             count++;
         }

src/core/thread/router_table.hpp

@@ -332,7 +332,14 @@ public:
     void ProcessTimerTick(void);
 
 private:
-    void UpdateAllocation(void);
+    void          UpdateAllocation(void);
+    const Router *GetFirstEntry(void) const;
+    const Router *GetNextEntry(const Router *aRouter) const;
+    Router *GetFirstEntry(void) { return const_cast<Router *>(const_cast<const RouterTable *>(this)->GetFirstEntry()); }
+    Router *GetNextEntry(Router *aRouter)
+    {
+        return const_cast<Router *>(const_cast<const RouterTable *>(this)->GetNextEntry(aRouter));
+    }
 
     Router   mRouters[Mle::kMaxRouters];
     uint8_t  mAllocatedRouterIds[BitVectorBytes(Mle::kMaxRouterId)];