policy: only send preferred candidate with transition request

Only send the preferred candidate with a BSS transition request.
Otherwise, unsuitable candidates might be included in the neighbor-list
of a transition request.

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

local_node.c

@@ -736,7 +736,7 @@ usteer_local_node_process_bss_tm_queries(struct uloop_timeout *timeout)
 		if (!si)
 			continue;
 
-		usteer_ubus_bss_transition_request(si, query->dialog_token, false, false, validity_period);
+		usteer_ubus_bss_transition_request(si, query->dialog_token, false, false, validity_period, NULL);
 	}
 
 	/* Free pending queries we can not handle */

policy.c

@@ -114,7 +114,7 @@ is_better_candidate(struct sta_info *si_cur, struct sta_info *si_new)
 static struct sta_info *
 find_better_candidate(struct sta_info *si_ref, struct uevent *ev, uint32_t required_criteria, uint64_t max_age)
 {
-	struct sta_info *si;
+	struct sta_info *si, *candidate = NULL;
 	struct sta *sta = si_ref->sta;
 	uint32_t reasons;
 
@@ -143,10 +143,11 @@ find_better_candidate(struct sta_info *si_ref, struct uevent *ev, uint32_t requi
 			ev->select_reasons = reasons;
 		}
 
-		return si;
+		if (candidate && si->signal > candidate->signal)
+			candidate = si;
 	}
 
-	return NULL;
+	return candidate;
 }
 
 int
@@ -297,25 +298,26 @@ usteer_roam_sm_start_scan(struct sta_info *si, struct uevent *ev)
 	usteer_roam_set_state(si, ROAM_TRIGGER_IDLE, ev);
 }
 
-static bool
+static struct sta_info *
 usteer_roam_sm_found_better_node(struct sta_info *si, struct uevent *ev, enum roam_trigger_state next_state)
 {
 	uint64_t max_age = 2 * config.roam_scan_interval;
+	struct sta_info *candidate;
 
 	if (max_age > current_time - si->roam_scan_start)
 		max_age = current_time - si->roam_scan_start;
 
-	if (find_better_candidate(si, ev, (1 << UEV_SELECT_REASON_SIGNAL), max_age)) {
+	candidate = find_better_candidate(si, ev, (1 << UEV_SELECT_REASON_SIGNAL), max_age);
+	if (candidate)
 		usteer_roam_set_state(si, next_state, ev);
-		return true;
-	}
 
-	return false;
+	return candidate;
 }
 
 static bool
 usteer_roam_trigger_sm(struct usteer_local_node *ln, struct sta_info *si)
 {
+	struct sta_info *candidate;
 	struct uevent ev = {
 		.si_cur = si,
 	};
@@ -357,7 +359,12 @@ usteer_roam_trigger_sm(struct usteer_local_node *ln, struct sta_info *si)
 		break;
 
 	case ROAM_TRIGGER_SCAN_DONE:
-		usteer_ubus_bss_transition_request(si, 1, false, false, 100);
+		candidate = usteer_roam_sm_found_better_node(si, &ev, ROAM_TRIGGER_SCAN_DONE);
+		/* Kick back in case no better node is found */
+		if (!candidate)
+			usteer_roam_set_state(si, ROAM_TRIGGER_IDLE, &ev);
+
+		usteer_ubus_bss_transition_request(si, 1, false, false, 100, candidate->node);
 		si->kick_time = current_time;
 		usteer_roam_set_state(si, ROAM_TRIGGER_IDLE, &ev);
 		break;

ubus.c

@@ -611,6 +611,16 @@ usteer_add_nr_entry(struct usteer_node *ln, struct usteer_node *node)
 	return true;
 }
 
+static void
+usteer_ubus_disassoc_add_neighbor(struct sta_info *si, struct usteer_node *node)
+{
+	void *c;
+
+	c = blobmsg_open_array(&b, "neighbors");
+	usteer_add_nr_entry(si->node, node);
+	blobmsg_close_array(&b, c);
+}
+
 static void
 usteer_ubus_disassoc_add_neighbors(struct sta_info *si)
 {
@@ -646,7 +656,8 @@ int usteer_ubus_bss_transition_request(struct sta_info *si,
 				       uint8_t dialog_token,
 				       bool disassoc_imminent,
 				       bool abridged,
-				       uint8_t validity_period)
+				       uint8_t validity_period,
+				       struct usteer_node *target_node)
 {
 	struct usteer_local_node *ln = container_of(si->node, struct usteer_local_node, node);
 
@@ -656,7 +667,11 @@ int usteer_ubus_bss_transition_request(struct sta_info *si,
 	blobmsg_add_u8(&b, "disassociation_imminent", disassoc_imminent);
 	blobmsg_add_u8(&b, "abridged", abridged);
 	blobmsg_add_u32(&b, "validity_period", validity_period);
+	if (!target_node) {
 		usteer_ubus_disassoc_add_neighbors(si);
+	} else {
+		usteer_ubus_disassoc_add_neighbor(si, target_node);
+	}
 	return ubus_invoke(ubus_ctx, ln->obj_id, "bss_transition_request", b.head, NULL, 0, 100);
 }
 

usteer.h

@@ -336,7 +336,8 @@ int usteer_ubus_bss_transition_request(struct sta_info *si,
 				       uint8_t dialog_token,
 				       bool disassoc_imminent,
 				       bool abridged,
-				       uint8_t validity_period);
+				       uint8_t validity_period,
+				       struct usteer_node *target_node);
 
 struct sta *usteer_sta_get(const uint8_t *addr, bool create);
 struct sta_info *usteer_sta_info_get(struct sta *sta, struct usteer_node *node, bool *create);