[PATCH v4 08/11] station: roam blacklist AP even mid-roam

[James Prestwood <prestwoj@gmail.com>]

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(-)

diff --git a/src/station.c b/src/station.c
index 623cfdca..c5529842 100644
--- a/src/station.c
+++ b/src/station.c
@@ -3225,12 +3225,10 @@ 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;
@@ -3294,8 +3292,13 @@ 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;
@@ -3322,15 +3325,24 @@ 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,
-- 
2.34.1