From 4fe428d0793231c1fa6dd378a3e4b172c21ed8f9 Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Wed, 15 May 2024 10:29:07 -0700
Subject: [PATCH] [network-data] optimize `ContainsOmrPrefix()` (#10239)

This commit simplifies the `Leader::ContainsOmrPrefix()` method by
eliminating the loop over sub-TLVs based on stable flag status. Since
OMR prefixes must be marked as stable, the search for a given OMR
prefix can be restricted to stable sub-TLV only.
---
 src/core/thread/network_data_leader.hpp     |  2 +-
 src/core/thread/network_data_leader_ftd.cpp | 40 ++++++++++-----------
 2 files changed, 19 insertions(+), 23 deletions(-)

diff --git a/src/core/thread/network_data_leader.hpp b/src/core/thread/network_data_leader.hpp
index 4ad1a99f0..597689199 100644
--- a/src/core/thread/network_data_leader.hpp
+++ b/src/core/thread/network_data_leader.hpp
@@ -431,7 +431,7 @@ public:
      * @retval FALSE Otherwise.
      *
      */
-    bool ContainsOmrPrefix(const Ip6::Prefix &aPrefix);
+    bool ContainsOmrPrefix(const Ip6::Prefix &aPrefix) const;
 #endif
 
 #endif // OPENTHREAD_FTD
diff --git a/src/core/thread/network_data_leader_ftd.cpp b/src/core/thread/network_data_leader_ftd.cpp
index 5cfc44e56..5905ced3d 100644
--- a/src/core/thread/network_data_leader_ftd.cpp
+++ b/src/core/thread/network_data_leader_ftd.cpp
@@ -1358,44 +1358,40 @@ void Leader::HandleTimer(void)
     }
 }
 
-#if OPENTHREAD_FTD && OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE
-bool Leader::ContainsOmrPrefix(const Ip6::Prefix &aPrefix)
+#if OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE
+
+bool Leader::ContainsOmrPrefix(const Ip6::Prefix &aPrefix) const
 {
-    PrefixTlv *prefixTlv;
-    bool       contains = false;
+    bool                   contains = false;
+    const PrefixTlv       *prefixTlv;
+    const BorderRouterTlv *brSubTlv;
 
     VerifyOrExit(BorderRouter::RoutingManager::IsValidOmrPrefix(aPrefix));
 
     prefixTlv = FindPrefix(aPrefix);
     VerifyOrExit(prefixTlv != nullptr);
 
-    for (int i = 0; i < 2; i++)
+    brSubTlv = prefixTlv->FindSubTlv<BorderRouterTlv>(/* aStable */ true);
+
+    VerifyOrExit(brSubTlv != nullptr);
+
+    for (const BorderRouterEntry *entry = brSubTlv->GetFirstEntry(); entry <= brSubTlv->GetLastEntry(); entry++)
     {
-        const BorderRouterTlv *borderRouter = prefixTlv->FindSubTlv<BorderRouterTlv>(/* aStable */ (i == 0));
+        OnMeshPrefixConfig config;
 
-        if (borderRouter == nullptr)
+        config.SetFrom(*prefixTlv, *brSubTlv, *entry);
+
+        if (BorderRouter::RoutingManager::IsValidOmrPrefix(config))
         {
-            continue;
-        }
-
-        for (const BorderRouterEntry *entry = borderRouter->GetFirstEntry(); entry <= borderRouter->GetLastEntry();
-             entry                          = entry->GetNext())
-        {
-            OnMeshPrefixConfig config;
-
-            config.SetFrom(*prefixTlv, *borderRouter, *entry);
-
-            if (BorderRouter::RoutingManager::IsValidOmrPrefix(config))
-            {
-                ExitNow(contains = true);
-            }
+            ExitNow(contains = true);
         }
     }
 
 exit:
     return contains;
 }
-#endif
+
+#endif // OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE
 
 //---------------------------------------------------------------------------------------------------------------------
 // Leader::ContextIds