policy: make roam-steers client-rejectable

While usteer tries it's best to determine the availability of a better
node for a certain client, it might still attempt to direct the client
to a unsuitable AP.

Transition away from using BSS-Transition-Requests with the
disassoc-imminent bit set and instead unset this bit.

This way, the client can inform the AP it will not transition to a
different BSS but instead wishes to remain connected to the current AP.

usteer will still kick clients in case they either accepted the
BSS-transition-request and do not roam or ignore the request completely.

Signed-off-by: David Bauer <mail@david-bauer.net>

local_node.c

@@ -180,6 +180,11 @@ usteer_handle_bss_tm_response(struct usteer_local_node *ln, struct blob_attr *ms
 	si->bss_transition_response.status_code = blobmsg_get_u8(tb[BSS_TM_RESPONSE_STATUS_CODE]);
 	si->bss_transition_response.timestamp = current_time;
 
+	if (si->bss_transition_response.status_code) {
+		/* Cancel imminent kick in case BSS transition was rejected */
+		si->kick_time = 0;
+	}
+
 	return 0;
 }
 

policy.c

@@ -314,14 +314,11 @@ usteer_roam_sm_found_better_node(struct sta_info *si, struct uevent *ev, enum ro
 }
 
 static bool
-usteer_roam_trigger_sm(struct sta_info *si)
+usteer_roam_trigger_sm(struct usteer_local_node *ln, struct sta_info *si)
 {
 	struct uevent ev = {
 		.si_cur = si,
 	};
-	uint64_t min_signal;
-
-	min_signal = usteer_snr_to_signal(si->node, config.roam_trigger_snr);
 
 	switch (si->roam_state) {
 	case ROAM_TRIGGER_SCAN:
@@ -341,7 +338,7 @@ usteer_roam_trigger_sm(struct sta_info *si)
 		if (config.roam_scan_tries && si->roam_tries >= config.roam_scan_tries) {
 			if (!config.roam_scan_timeout) {
 				/* Prepare to kick client */
-				usteer_roam_set_state(si, ROAM_TRIGGER_WAIT_KICK, &ev);
+				usteer_roam_set_state(si, ROAM_TRIGGER_SCAN_DONE, &ev);
 			} else {
 				/* Kick in scan timeout */
 				si->roam_scan_timeout_start = current_time;
@@ -360,30 +357,10 @@ usteer_roam_trigger_sm(struct sta_info *si)
 		break;
 
 	case ROAM_TRIGGER_SCAN_DONE:
-		if (usteer_roam_sm_found_better_node(si, &ev, ROAM_TRIGGER_WAIT_KICK))
+		usteer_ubus_bss_transition_request(si, 1, false, false, 100);
-			break;
+		si->kick_time = current_time;
-
-		/* Kick back to SCAN state if candidate expired */
-		usteer_roam_sm_start_scan(si, &ev);
-		break;
-
-	case ROAM_TRIGGER_WAIT_KICK:
-		if (si->signal > min_signal)
-			break;
-
-		usteer_roam_set_state(si, ROAM_TRIGGER_NOTIFY_KICK, &ev);
-		usteer_ubus_notify_client_disassoc(si);
-		break;
-	case ROAM_TRIGGER_NOTIFY_KICK:
-		if (current_time - si->roam_event < config.roam_kick_delay * 100)
-			break;
-
-		usteer_roam_set_state(si, ROAM_TRIGGER_KICK, &ev);
-		break;
-	case ROAM_TRIGGER_KICK:
-		usteer_ubus_kick_client(si);
 		usteer_roam_set_state(si, ROAM_TRIGGER_IDLE, &ev);
-		return true;
+		break;
 	}
 
 	return false;
@@ -407,6 +384,7 @@ usteer_local_node_roam_check(struct usteer_local_node *ln, struct uevent *ev)
 
 	list_for_each_entry(si, &ln->node.sta_info, node_list) {
 		if (si->connected != STA_CONNECTED || si->signal >= min_signal ||
+			si->kick_time ||
 		    current_time - si->roam_kick < config.roam_trigger_interval) {
 			usteer_roam_set_state(si, ROAM_TRIGGER_IDLE, ev);
 			continue;
@@ -416,7 +394,7 @@ usteer_local_node_roam_check(struct usteer_local_node *ln, struct uevent *ev)
 		 * If the state machine kicked a client, other clients should wait
 		 * until the next turn
 		 */
-		if (usteer_roam_trigger_sm(si))
+		if (usteer_roam_trigger_sm(ln, si))
 			return;
 	}
 }
@@ -548,6 +526,18 @@ out:
 	usteer_event(&ev);
 }
 
+static void
+usteer_local_node_perform_kick(struct usteer_local_node *ln)
+{
+	struct sta_info *si;
+
+	list_for_each_entry(si, &ln->node.sta_info, node_list) {
+		if (!si->kick_time || si->kick_time > current_time)
+			continue;
+
+		usteer_ubus_kick_client(si);
+	}
+}
 
 void
 usteer_local_node_kick(struct usteer_local_node *ln)
@@ -556,6 +546,8 @@ usteer_local_node_kick(struct usteer_local_node *ln)
 		.node_local = &ln->node,
 	};
 
+	usteer_local_node_perform_kick(ln);
+
 	usteer_local_node_snr_kick(ln);
 	usteer_local_node_load_kick(ln);
 	usteer_local_node_roam_check(ln, &ev);

sta.c

@@ -149,6 +149,7 @@ usteer_sta_get(const uint8_t *addr, bool create)
 void usteer_sta_disconnected(struct sta_info *si)
 {
 	si->connected = STA_NOT_CONNECTED;
+	si->kick_time = 0;
 	usteer_sta_info_update_timeout(si, config.local_sta_timeout);
 }
 

usteer.h

@@ -219,9 +219,6 @@ enum roam_trigger_state {
 	ROAM_TRIGGER_IDLE,
 	ROAM_TRIGGER_SCAN,
 	ROAM_TRIGGER_SCAN_DONE,
-	ROAM_TRIGGER_WAIT_KICK,
-	ROAM_TRIGGER_NOTIFY_KICK,
-	ROAM_TRIGGER_KICK,
 };
 
 struct sta_info {
@@ -254,6 +251,8 @@ struct sta_info {
 		uint64_t timestamp;
 	} bss_transition_response;
 
+	uint64_t kick_time;
+
 	int kick_count;
 
 	uint32_t below_min_snr;