From f5c93ad802e943e5f700e4a7ce30d17a88fd7175 Mon Sep 17 00:00:00 2001
From: Eduardo Montoya <eduardo.montoya@nordicsemi.no>
Date: Mon, 9 Dec 2024 11:11:17 +0100
Subject: [PATCH] Add Mle::FindCslNeighbor

---
 src/core/mac/mac.cpp    | 15 ++-------------
 src/core/thread/mle.cpp | 22 ++++++++++++++++++++++
 src/core/thread/mle.hpp | 14 +++++++++++---
 3 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/src/core/mac/mac.cpp b/src/core/mac/mac.cpp
index 950ab0cdd418..18e7731fe134 100644
--- a/src/core/mac/mac.cpp
+++ b/src/core/mac/mac.cpp
@@ -2473,26 +2473,15 @@ bool Mac::IsCslSupported(void) const
 
 void Mac::ProcessCsl(const RxFrame &aFrame, const Address &aSrcAddr)
 {
-    CslNeighbor *neighbor = nullptr;
+    CslNeighbor *neighbor = Get<Mle::Mle>().FindCslNeighbor(aSrcAddr);
     const CslIe *csl;
 
-    OT_UNUSED_VARIABLE(aSrcAddr);
-
+    VerifyOrExit(neighbor != nullptr);
     VerifyOrExit(aFrame.IsVersion2015() && aFrame.GetSecurityEnabled());
 
     csl = aFrame.GetCslIe();
     VerifyOrExit(csl != nullptr);
 
-#if OPENTHREAD_FTD
-    neighbor = Get<ChildTable>().FindChild(aSrcAddr, Child::kInStateAnyExceptInvalid);
-#endif
-
-#if OPENTHREAD_CONFIG_WAKEUP_END_DEVICE_ENABLE
-    neighbor = neighbor == nullptr ? Get<Mle::Mle>().GetWakeupParent() : neighbor;
-#endif
-
-    VerifyOrExit(neighbor != nullptr);
-
 #if OPENTHREAD_CONFIG_WAKEUP_END_DEVICE_ENABLE
     VerifyOrExit(neighbor->GetExtAddress() == aSrcAddr.GetExtended());
 #endif
diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index 6c1aae0632cc..e6477db2cab6 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -5654,6 +5654,28 @@ void Mle::AttachToWakeupParent()
 }
 #endif // OPENTHREAD_CONFIG_WAKEUP_END_DEVICE_ENABLE
 
+#if OPENTHREAD_CONFIG_MAC_CSL_TRANSMITTER_ENABLE
+CslNeighbor *Mle::FindCslNeighbor(const Mac::Address &aAddress)
+{
+    CslNeighbor *neighbor = nullptr;
+
+#if OPENTHREAD_FTD
+    neighbor = Get<ChildTable>().FindChild(aAddress, Child::kInStateAnyExceptInvalid);
+#endif
+
+#if OPENTHREAD_CONFIG_WAKEUP_END_DEVICE_ENABLE
+    OT_UNUSED_VARIABLE(aAddress);
+
+    if (neighbor == nullptr)
+    {
+        neighbor = GetWakeupParent();
+    }
+#endif
+
+    return neighbor;
+}
+#endif
+
 //---------------------------------------------------------------------------------------------------------------------
 // ParentCandidate
 
diff --git a/src/core/thread/mle.hpp b/src/core/thread/mle.hpp
index be96c5a0a24b..0e858d1bb77d 100644
--- a/src/core/thread/mle.hpp
+++ b/src/core/thread/mle.hpp
@@ -118,9 +118,6 @@ class Mle : public InstanceLocator, private NonCopyable
     friend class ot::LinkMetrics::Initiator;
 #endif
     friend class ot::UnitTester;
-#if OPENTHREAD_CONFIG_WAKEUP_END_DEVICE_ENABLE
-    friend class ot::Mac::Mac;
-#endif
 
 public:
     typedef otDetachGracefullyCallback DetachCallback; ///< Callback to signal end of graceful detach.
@@ -786,6 +783,17 @@ class Mle : public InstanceLocator, private NonCopyable
     void AttachToWakeupParent();
 #endif
 
+#if OPENTHREAD_CONFIG_MAC_CSL_TRANSMITTER_ENABLE
+    /**
+     * Returns a CSL Neighbor by its address.
+     *
+     * @param[in] aAddress The address of the CSL Neighbor.
+     * 
+     * @returns A pointer to the CSL Neighbor, or NULL if not found.
+     */
+    CslNeighbor *FindCslNeighbor(const Mac::Address &aAddress);
+#endif
+
 private:
     //------------------------------------------------------------------------------------------------------------------
     // Constants