From c5971f7080f9f8e33bb3da54db1c66a2319cac2a Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Tue, 7 Oct 2025 14:49:16 -0700
Subject: [PATCH] [border-agent] check that BA is enabled in
 `RegisterService()` (#11993)

This change adds a check at the beginning of `RegisterService()`
to ensure that the border agent is enabled before attempting to
register a service.

Previously, methods like `SetServiceBaseName()` would call
`RegisterService()` regardless of whether the agent was enabled,
leading to unintended service registration attempts on a disabled
agent.

This commit also adds a new test case to verify that changing the
service base name on a disabled border agent does not result in a
service being registered.
---
 src/core/meshcop/border_agent.cpp |  1 +
 tests/nexus/test_border_agent.cpp | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/src/core/meshcop/border_agent.cpp b/src/core/meshcop/border_agent.cpp
index ff6635cbf..2f14be12f 100644
--- a/src/core/meshcop/border_agent.cpp
+++ b/src/core/meshcop/border_agent.cpp
@@ -466,6 +466,7 @@ void BorderAgent::RegisterService(void)
     uint16_t       txtDataBufferSize;
     uint16_t       txtDataLength;
 
+    VerifyOrExit(IsEnabled());
     VerifyOrExit(Get<Dnssd>().IsReady());
 
     // Allocate a large enough buffer to fit both the TXT data
diff --git a/tests/nexus/test_border_agent.cpp b/tests/nexus/test_border_agent.cpp
index 51fe3502c..08794d04c 100644
--- a/tests/nexus/test_border_agent.cpp
+++ b/tests/nexus/test_border_agent.cpp
@@ -1786,6 +1786,26 @@ void TestBorderAgentServiceRegistration(void)
 
     sBrowseOutcomes.Clear();
 
+    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+    Log("Change the base service name while agent is disabled and validate no service is registered");
+
+    SuccessOrQuit(node0.Get<MeshCoP::BorderAgent>().SetServiceBaseName("NewName"));
+
+    VerifyOrQuit(!node0.Get<MeshCoP::BorderAgent>().IsEnabled());
+
+    nexus.AdvanceTime(30 * Time::kOneSecondInMsec);
+
+    iterator = node0.Get<Dns::Multicast::Core>().AllocateIterator();
+    VerifyOrQuit(iterator != nullptr);
+
+    VerifyOrQuit(node0.Get<Dns::Multicast::Core>().GetNextService(*iterator, service, entryState) == kErrorNotFound);
+
+    node0.Get<Dns::Multicast::Core>().FreeIterator(*iterator);
+
+    VerifyOrQuit(sBrowseOutcomes.IsEmpty());
+
+    SuccessOrQuit(node0.Get<MeshCoP::BorderAgent>().SetServiceBaseName("OpenThreadAgent"));
+
     // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     Log("Re-enable Border Agent and validate that service is registered again");