[router-table] rename FindNextHopOf() to FindNextHopTowards() (openthread#13008)

This commit renames the `RouterTable::FindNextHopOf()` method to
`RouterTable::FindNextHopTowards()` to more accurately reflect its
purpose: finding the next hop on the path towards a given destination
router.

Author: abtink

src/core/thread/mle_ftd.cpp

@@ -1799,7 +1799,7 @@ void Mle::HandleTimeTick(void)
             continue;
         }
 
-        if (IsLeader() && (mRouterTable.FindNextHopOf(router) == nullptr) &&
+        if (IsLeader() && (mRouterTable.FindNextHopTowards(router) == nullptr) &&
             (mRouterTable.GetLinkCost(router) >= kMaxRouteCost) && (age >= kMaxLeaderToRouterTimeout))
         {
             LogInfo("Router 0x%04x ID timeout expired (no route)", router.GetRloc16());

src/core/thread/router_table.cpp

@@ -317,7 +317,10 @@ const Router *RouterTable::FindRouterByRloc16(uint16_t aRloc16) const
     return FindRouterById(Mle::RouterIdFromRloc16(aRloc16));
 }
 
-const Router *RouterTable::FindNextHopOf(const Router &aRouter) const { return FindRouterById(aRouter.GetNextHop()); }
+const Router *RouterTable::FindNextHopTowards(const Router &aRouter) const
+{
+    return FindRouterById(aRouter.GetNextHop());
+}
 
 Router *RouterTable::FindRouter(const Mac::ExtAddress &aExtAddress)
 {
@@ -431,7 +434,7 @@ void RouterTable::GetNextHopAndPathCost(uint16_t aDestRloc16, uint16_t &aNextHop
     }
 
     router  = FindRouterById(Mle::RouterIdFromRloc16(aDestRloc16));
-    nextHop = (router != nullptr) ? FindNextHopOf(*router) : nullptr;
+    nextHop = (router != nullptr) ? FindNextHopTowards(*router) : nullptr;
 
     if (Get<Mle::Mle>().IsChild())
     {
@@ -663,7 +666,7 @@ void RouterTable::UpdateRoutes(const Mle::RouteTlv &aRouteTlv, uint8_t aNeighbor
             continue;
         }
 
-        nextHop = FindNextHopOf(*router);
+        nextHop = FindNextHopTowards(*router);
 
         cost = aRouteTlv.GetRouteCost(index);
         cost = (cost == 0) ? Mle::kMaxRouteCost : cost;

src/core/thread/router_table.hpp

@@ -242,22 +242,22 @@ class RouterTable : public InstanceLocator, private NonCopyable
     const Router *FindRouterByRloc16(uint16_t aRloc16) const;
 
     /**
-     * Finds the router that is the next hop of a given router.
+     * Finds the router that is the next hop towards a given router.
      *
-     * @param[in]  aRouter  The router to find next hop of.
+     * @param[in]  aRouter  The destination router.
      *
      * @returns A pointer to the router or `nullptr` if the router could not be found.
      */
-    Router *FindNextHopOf(const Router &aRouter) { return AsNonConst(AsConst(this)->FindNextHopOf(aRouter)); }
+    Router *FindNextHopTowards(const Router &aRouter) { return AsNonConst(AsConst(this)->FindNextHopTowards(aRouter)); }
 
     /**
-     * Finds the router that is the next hop of a given router.
+     * Finds the router that is the next hop towards a given router.
      *
-     * @param[in]  aRouter  The router to find next hop of.
+     * @param[in]  aRouter  The destination router.
      *
      * @returns A pointer to the router or `nullptr` if the router could not be found.
      */
-    const Router *FindNextHopOf(const Router &aRouter) const;
+    const Router *FindNextHopTowards(const Router &aRouter) const;
 
     /**
      * Find the router for a given MAC Extended Address.