From a8e1bb27219bb2ebea1126cad07b33937f3ab155 Mon Sep 17 00:00:00 2001
From: Rahix <rahix@rahix.de>
Date: Sat, 25 Apr 2026 15:17:48 +0200
Subject: [PATCH 1/2] fdl: active: Ensure GAP never scans own address

Add a debug assertion to ensure the GAP scan never sends a status
request to the address of the active station itself.
---
 src/fdl/active.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/fdl/active.rs b/src/fdl/active.rs
index 5dcdf7a..674b5bc 100644
--- a/src/fdl/active.rs
+++ b/src/fdl/active.rs
@@ -1128,6 +1128,8 @@ impl FdlActiveStation {
             }
 
             if let GapState::DoPoll { current_address } = self.gap_state {
+                debug_assert_ne!(current_address, self.p.address);
+
                 let tx_res = phy
                     .transmit_telegram(now, |tx| {
                         Some(tx.send_fdl_status_request(current_address, self.p.address))

From 00608ab106b9c15a8d98051615ba398ec7a0e3e8 Mon Sep 17 00:00:00 2001
From: Rahix <rahix@rahix.de>
Date: Sat, 25 Apr 2026 15:23:32 +0200
Subject: [PATCH 2/2] fdl: tests: Add test for discovering direct neighbor
 stations

The active station implementation already correctly discovers direct
neighbors but no test ever verified that this works.  To catch any
regressions in the future, add a test case for this condition.
---
 src/fdl/test_active.rs | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/src/fdl/test_active.rs b/src/fdl/test_active.rs
index 3c71db2..2102f11 100644
--- a/src/fdl/test_active.rs
+++ b/src/fdl/test_active.rs
@@ -565,6 +565,36 @@ fn active_station_discovers_neighbor() {
     fdl_ut.wait_for_matching(|t| t == fdl::Telegram::Token(fdl::TokenTelegram { da: 4, sa: 7 }));
 }
 
+/// Test that an active station discovers a direct (active) neighbor station.
+#[test]
+fn active_station_discovers_direct_neighbor() {
+    crate::test_utils::prepare_test_logger();
+    let mut fdl_ut = FdlActiveUnderTest::new(7);
+
+    fdl_ut.wait_for_matching(|t| {
+        if let fdl::Telegram::Data(data_telegram) = t {
+            data_telegram.is_fdl_status_request().is_some()
+                && data_telegram.h.da == 8
+                && data_telegram.h.sa == 7
+        } else {
+            false
+        }
+    });
+
+    fdl_ut.advance_bus_time_min_tsdr();
+    fdl_ut.transmit_telegram(|tx| {
+        Some(tx.send_fdl_status_response(
+            7,
+            8,
+            fdl::ResponseState::MasterWithoutToken,
+            fdl::ResponseStatus::Ok,
+        ))
+    });
+    fdl_ut.wait_transmission();
+
+    fdl_ut.wait_for_matching(|t| t == fdl::Telegram::Token(fdl::TokenTelegram { da: 8, sa: 7 }));
+}
+
 /// Test that an active station resends the token when not received by next station
 #[test]
 fn active_station_resends_token() {