From e2e36d61e7709370654e2d5f991206f0d5e3138a Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Thu, 26 Mar 2026 22:48:05 -0700
Subject: [PATCH] [thread] simplify `ThreadNetworkDataTlv` definition (#12770)

This commit simplifies the definition of `ThreadNetworkDataTlv`.
Previously, `ThreadNetworkDataTlv` included a 255-byte array to store
the Network Data TLVs. The code now relies on standard TLV parsing
methods like `Tlv::FindTlvValueOffsetRange()` and `Message::ReadBytes()`
to access the Network Data directly from the message payload.
---
 src/core/thread/network_data_leader_ftd.cpp | 14 ++++++---
 src/core/thread/network_data_notifier.cpp   |  4 +--
 src/core/thread/thread_tlvs.hpp             | 35 ++-------------------
 3 files changed, 13 insertions(+), 40 deletions(-)

diff --git a/src/core/thread/network_data_leader_ftd.cpp b/src/core/thread/network_data_leader_ftd.cpp
index 2629d18bb..7396f9804 100644
--- a/src/core/thread/network_data_leader_ftd.cpp
+++ b/src/core/thread/network_data_leader_ftd.cpp
@@ -221,8 +221,8 @@ void Leader::RemoveBorderRouter(uint16_t aRloc16, MatchMode aMatchMode)
 
 template <> void Leader::HandleTmf<kUriServerData>(Coap::Msg &aMsg)
 {
-    ThreadNetworkDataTlv networkDataTlv;
-    uint16_t             rloc16;
+    uint16_t    rloc16;
+    OffsetRange offsetRange;
 
     VerifyOrExit(Get<Mle::Mle>().IsLeader() && !mWaitingForNetDataSync);
 
@@ -241,12 +241,16 @@ template <> void Leader::HandleTmf<kUriServerData>(Coap::Msg &aMsg)
         ExitNow();
     }
 
-    if (Tlv::FindTlv(aMsg.mMessage, networkDataTlv) == kErrorNone)
+    if (Tlv::FindTlvValueOffsetRange(aMsg.mMessage, ThreadNetworkDataTlv::kType, offsetRange) == kErrorNone)
     {
-        VerifyOrExit(networkDataTlv.IsValid());
+        uint8_t bytes[kMaxSize];
+
+        VerifyOrExit(offsetRange.GetLength() <= kMaxSize);
+
+        aMsg.mMessage.ReadBytes(offsetRange, bytes);
 
         {
-            NetworkData networkData(GetInstance(), networkDataTlv.GetTlvs(), networkDataTlv.GetLength());
+            NetworkData networkData(GetInstance(), bytes, static_cast<uint8_t>(offsetRange.GetLength()));
 
             RegisterNetworkData(aMsg.mMessageInfo.GetPeerAddr().GetIid().GetLocator(), networkData);
         }
diff --git a/src/core/thread/network_data_notifier.cpp b/src/core/thread/network_data_notifier.cpp
index e1685a27f..898d502b9 100644
--- a/src/core/thread/network_data_notifier.cpp
+++ b/src/core/thread/network_data_notifier.cpp
@@ -191,8 +191,8 @@ Error Notifier::SendServerDataNotification(uint16_t aOldRloc16, const NetworkDat
 
     if (aNetworkData != nullptr)
     {
-        SuccessOrExit(error = Tlv::AppendTlv(*message, ThreadTlv::kThreadNetworkData, aNetworkData->GetBytes(),
-                                             aNetworkData->GetLength()));
+        SuccessOrExit(
+            error = Tlv::Append<ThreadNetworkDataTlv>(*message, aNetworkData->GetBytes(), aNetworkData->GetLength()));
 
 #if OPENTHREAD_FTD && OPENTHREAD_CONFIG_BORDER_ROUTER_SIGNAL_NETWORK_DATA_FULL
         Get<Leader>().CheckForNetDataGettingFull(*aNetworkData, aOldRloc16);
diff --git a/src/core/thread/thread_tlvs.hpp b/src/core/thread/thread_tlvs.hpp
index 80380d731..3564d53a0 100644
--- a/src/core/thread/thread_tlvs.hpp
+++ b/src/core/thread/thread_tlvs.hpp
@@ -202,40 +202,9 @@ private:
 } OT_TOOL_PACKED_END;
 
 /**
- * Implements Thread Network Data TLV generation and parsing.
+ * Defines Thread Network Data TLV constants and types.
  */
-OT_TOOL_PACKED_BEGIN
-class ThreadNetworkDataTlv : public ThreadTlv, public TlvInfo<ThreadTlv::kThreadNetworkData>
-{
-public:
-    /**
-     * Initializes the TLV.
-     */
-    void Init(void)
-    {
-        SetType(kThreadNetworkData);
-        SetLength(0);
-    }
-
-    /**
-     * Overrides same method of the base class
-     *
-     * @retval TRUE  the TLV appears to be well-formed.
-     */
-    bool IsValid(void) const { return true; }
-
-    /**
-     * Returns a pointer to the Network Data TLVs.
-     *
-     * @returns A pointer to the Network Data TLVs.
-     */
-    uint8_t *GetTlvs(void) { return mTlvs; }
-
-private:
-    static constexpr uint8_t kMaxSize = 255;
-
-    uint8_t mTlvs[kMaxSize];
-} OT_TOOL_PACKED_END;
+typedef TlvInfo<ThreadTlv::kThreadNetworkData> ThreadNetworkDataTlv;
 
 #if OPENTHREAD_CONFIG_THREAD_VERSION >= OT_THREAD_VERSION_1_2