[v2,10/13] station: roam blacklist AP even mid-roam

Commit Message

James Prestwood March 24, 2025, 2:15 p.m. UTC

If an AP directed roam frame comes in while IWD is roaming its
still valuable to parse that frame and blacklist the BSS that
sent it.

This can happen most frequently during a roam scan while connected
to an overloaded BSS that is requesting IWD roams elsewhere.
---
 src/station.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

Patch

diff --git a/src/station.c b/src/station.c
index b96419be..066ca337 100644
--- a/src/station.c
+++ b/src/station.c
@@ -3162,12 +3162,10 @@  static void station_ap_directed_roam(struct station *station,
 	uint8_t req_mode;
 	uint16_t dtimer;
 	uint8_t valid_interval;
+	bool can_roam = !station_cannot_roam(station);
 
 	l_debug("ifindex: %u", netdev_get_ifindex(station->netdev));
 
-	if (station_cannot_roam(station))
-		return;
-
 	if (station->state != STATION_STATE_CONNECTED) {
 		l_debug("roam: unexpected AP directed roam -- ignore");
 		return;
@@ -3231,8 +3229,13 @@  static void station_ap_directed_roam(struct station *station,
 	 * disassociating us. If either of these bits are set, set the
 	 * ap_directed_roaming flag. Otherwise still try roaming but don't
 	 * treat it any different than a normal roam.
+	 *
+	 * The only exception here is if we are in the middle of roaming
+	 * (can_roam == false) since we cannot reliably know if the roam scan
+	 * included frequencies from potential candidates in this request,
+	 * forcing a roam in this case might result in unintended behavior.
 	 */
-	if (req_mode & (WNM_REQUEST_MODE_DISASSOCIATION_IMMINENT |
+	if (can_roam && req_mode & (WNM_REQUEST_MODE_DISASSOCIATION_IMMINENT |
 			WNM_REQUEST_MODE_TERMINATION_IMMINENT |
 			WNM_REQUEST_MODE_ESS_DISASSOCIATION_IMMINENT))
 		station->ap_directed_roaming = true;
@@ -3259,15 +3262,24 @@  static void station_ap_directed_roam(struct station *station,
 		pos += url_len;
 	}
 
+	blacklist_add_bss(station->connected_bss->addr,
+				BLACKLIST_REASON_ROAM_REQUESTED);
+	station_debug_event(station, "ap-roam-blacklist-added");
+
+	/*
+	 * Validating the frame and blacklisting should still be done even if
+	 * we are mid-roam. Its important to track the BSS requesting the
+	 * transition so when the current roam completes IWD will be less likely
+	 * to roam back to the current BSS.
+	 */
+	if (!can_roam)
+		return;
+
 	station->preparing_roam = true;
 
 	l_timeout_remove(station->roam_trigger_timeout);
 	station->roam_trigger_timeout = NULL;
 
-	blacklist_add_bss(station->connected_bss->addr,
-				BLACKLIST_REASON_ROAM_REQUESTED);
-	station_debug_event(station, "ap-roam-blacklist-added");
-
 	if (req_mode & WNM_REQUEST_MODE_PREFERRED_CANDIDATE_LIST) {
 		l_debug("roam: AP sent a preferred candidate list");
 		station_neighbor_report_cb(station->netdev, 0, body + pos,