From 13ac7297a0010c76a10665e6230154bdd31fe5ed Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Mon, 20 Feb 2023 21:20:57 -0800
Subject: [PATCH] [routing-manager] use NA target address (#8777)

This commit updates `ProcessNeighborAdvertMessage()` method in
`RoutingManager` to use the Target Address included in Neighbor
Advertisement to find the related `Router` (instead of sender's
IPv6 address). This addresses situations where the router
responding may use a different address.
---
 src/core/border_router/routing_manager.cpp | 16 ++++++++--------
 src/core/border_router/routing_manager.hpp |  5 ++---
 2 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/src/core/border_router/routing_manager.cpp b/src/core/border_router/routing_manager.cpp
index 31b12546a..f8e3d16e1 100644
--- a/src/core/border_router/routing_manager.cpp
+++ b/src/core/border_router/routing_manager.cpp
@@ -363,7 +363,7 @@ void RoutingManager::HandleReceived(const InfraIf::Icmp6Packet &aPacket, const I
         HandleRouterSolicit(aPacket, aSrcAddress);
         break;
     case Ip6::Icmp::Header::kTypeNeighborAdvert:
-        HandleNeighborAdvertisement(aPacket, aSrcAddress);
+        HandleNeighborAdvertisement(aPacket);
         break;
     default:
         break;
@@ -943,14 +943,14 @@ void RoutingManager::HandleRouterSolicit(const InfraIf::Icmp6Packet &aPacket, co
     ScheduleRoutingPolicyEvaluation(kToReplyToRs);
 }
 
-void RoutingManager::HandleNeighborAdvertisement(const InfraIf::Icmp6Packet &aPacket, const Ip6::Address &aSrcAddress)
+void RoutingManager::HandleNeighborAdvertisement(const InfraIf::Icmp6Packet &aPacket)
 {
     const Ip6::Nd::NeighborAdvertMessage *naMsg;
 
     VerifyOrExit(aPacket.GetLength() >= sizeof(naMsg));
     naMsg = reinterpret_cast<const Ip6::Nd::NeighborAdvertMessage *>(aPacket.GetBytes());
 
-    mDiscoveredPrefixTable.ProcessNeighborAdvertMessage(*naMsg, aSrcAddress);
+    mDiscoveredPrefixTable.ProcessNeighborAdvertMessage(*naMsg);
 
 exit:
     return;
@@ -1715,14 +1715,14 @@ void RoutingManager::DiscoveredPrefixTable::RemoveExpiredEntries(void)
 void RoutingManager::DiscoveredPrefixTable::SignalTableChanged(void) { mSignalTask.Post(); }
 
 void RoutingManager::DiscoveredPrefixTable::ProcessNeighborAdvertMessage(
-    const Ip6::Nd::NeighborAdvertMessage &aNaMessage,
-    const Ip6::Address                   &aSrcAddress)
+    const Ip6::Nd::NeighborAdvertMessage &aNaMessage)
 {
-    Router *router = mRouters.FindMatching(aSrcAddress);
+    Router *router;
 
-    VerifyOrExit(router != nullptr);
     VerifyOrExit(aNaMessage.IsValid());
-    VerifyOrExit(aNaMessage.GetTargetAddress() == router->mAddress);
+
+    router = mRouters.FindMatching(aNaMessage.GetTargetAddress());
+    VerifyOrExit(router != nullptr);
 
     LogInfo("Received NA from router %s", router->mAddress.ToString().AsCString());
 
diff --git a/src/core/border_router/routing_manager.hpp b/src/core/border_router/routing_manager.hpp
index a8b39d615..19e057d75 100644
--- a/src/core/border_router/routing_manager.hpp
+++ b/src/core/border_router/routing_manager.hpp
@@ -462,8 +462,7 @@ private:
 
         void ProcessRouterAdvertMessage(const Ip6::Nd::RouterAdvertMessage &aRaMessage,
                                         const Ip6::Address                 &aSrcAddress);
-        void ProcessNeighborAdvertMessage(const Ip6::Nd::NeighborAdvertMessage &aNaMessage,
-                                          const Ip6::Address                   &aSrcAddress);
+        void ProcessNeighborAdvertMessage(const Ip6::Nd::NeighborAdvertMessage &aNaMessage);
 
         void SetAllowDefaultRouteInNetData(bool aAllow);
 
@@ -868,7 +867,7 @@ private:
 
     void HandleRouterAdvertisement(const InfraIf::Icmp6Packet &aPacket, const Ip6::Address &aSrcAddress);
     void HandleRouterSolicit(const InfraIf::Icmp6Packet &aPacket, const Ip6::Address &aSrcAddress);
-    void HandleNeighborAdvertisement(const InfraIf::Icmp6Packet &aPacket, const Ip6::Address &aSrcAddress);
+    void HandleNeighborAdvertisement(const InfraIf::Icmp6Packet &aPacket);
     bool ShouldProcessPrefixInfoOption(const Ip6::Nd::PrefixInfoOption &aPio, const Ip6::Prefix &aPrefix);
     bool ShouldProcessRouteInfoOption(const Ip6::Nd::RouteInfoOption &aRio, const Ip6::Prefix &aPrefix);
     void UpdateDiscoveredPrefixTableOnNetDataChange(void);