node: keep track of roam-sources and roam-destinations

Keep track of STA journeys between multiple nodes. When a new STA is
reported from a foreign node, check whether this STA was previously
associated with a local node.

Vice versa, check upon association whether or not the STA was previously
associated with a foreign node.

Keep track of these roaming transactions using two new (local) fields of
the node struct.

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

local_node.c

@@ -150,10 +150,29 @@ usteer_local_node_assoc_update(struct sta_info *si, struct blob_attr *data)
 		[MSG_ASSOC] = { "assoc", BLOBMSG_TYPE_BOOL },
 	};
 	struct blob_attr *tb[__MSG_MAX];
+	struct usteer_remote_node *rn;
+	struct sta_info *remote_si;
 
 	blobmsg_parse(policy, __MSG_MAX, tb, blobmsg_data(data), blobmsg_data_len(data));
-	if (tb[MSG_ASSOC] && blobmsg_get_u8(tb[MSG_ASSOC]))
+	if (tb[MSG_ASSOC] && blobmsg_get_u8(tb[MSG_ASSOC])) {
+		if (si->connected == STA_NOT_CONNECTED) {
+			/* New connection. Check if STA roamed. */
+			for_each_remote_node(rn) {
+				remote_si = usteer_sta_info_get(si->sta, &rn->node, NULL);
+				if (!remote_si)
+					continue;
+
+				if (current_time - remote_si->last_connected < config.roam_process_timeout) {
+					rn->node.roam_source++;
+					/* Don't abort looking for roam sources here.
+					 * The client might have roamed via another node
+					 * within the roam-timeout.
+					 */
+				}
+			}
+		}
 		si->connected = STA_CONNECTED;
+	}
 
 	if (si->node->freq < 4000)
 		si->sta->seen_2ghz = 1;

main.c

@@ -96,6 +96,7 @@ void usteer_init_defaults(void)
 	config.remote_node_timeout = 10;
 
 	config.roam_kick_delay = 100;
+	config.roam_process_timeout = 5 * 1000;
 	config.roam_scan_tries = 3;
 	config.roam_scan_interval = 10 * 1000;
 	config.roam_trigger_interval = 60 * 1000;

openwrt/usteer/files/etc/config/usteer

@@ -50,6 +50,10 @@ config usteer
 	# Minimum signal-to-noise ratio or signal level (dBm) to remain connected
 	#option min_snr 0
 
+	# Timeout (in ms) after which a association following a disassociation is not seen
+	# as a roam
+	#option roam_process_timeout 5000
+
 	# Minimum signal-to-noise ratio or signal level (dBm) before attempting to trigger
 	# client scans for roaming
 	#option roam_scan_snr 0

openwrt/usteer/files/etc/init.d/usteer

@@ -79,7 +79,7 @@ uci_usteer() {
 		load_balancing_threshold band_steering_threshold \
 		remote_update_interval \
 		min_connect_snr min_snr signal_diff_threshold \
-		initial_connect_delay \
+		initial_connect_delay roam_process_timeout\
 		roam_kick_delay roam_scan_tries \
 		roam_scan_snr roam_scan_interval \
 		roam_trigger_snr roam_trigger_interval \

remote.c

@@ -155,9 +155,11 @@ static void
 interface_add_station(struct usteer_remote_node *node, struct blob_attr *data)
 {
 	struct sta *sta;
-	struct sta_info *si;
+	struct sta_info *si, *local_si;
 	struct apmsg_sta msg;
+	struct usteer_node *local_node;
 	bool create;
+	bool connect_change;
 
 	if (!parse_apmsg_sta(&msg, data)) {
 		MSG(DEBUG, "Cannot parse station in message\n");
@@ -177,10 +179,26 @@ interface_add_station(struct usteer_remote_node *node, struct blob_attr *data)
 	if (!si)
 		return;
 
+	connect_change = si->connected != msg.connected;
 	si->connected = msg.connected;
 	si->signal = msg.signal;
 	si->seen = current_time - msg.seen;
 	si->last_connected = current_time - msg.last_connected;
+
+	/* Check if client roamed to this foreign node */
+	if ((connect_change || create) && si->connected == STA_CONNECTED) {
+		for_each_local_node(local_node) {
+			local_si = usteer_sta_info_get(sta, local_node, NULL);
+			if (!local_si)
+				continue;
+
+			if (current_time - local_si->last_connected < config.roam_process_timeout) {
+				node->node.roam_destination++;
+				break;
+			}
+		}
+	}
+
 	usteer_sta_info_update_timeout(si, msg.timeout);
 }
 

ubus.c

@@ -154,6 +154,7 @@ struct cfg_item {
 	_cfg(BOOL, assoc_steering), \
 	_cfg(I32, min_connect_snr), \
 	_cfg(I32, min_snr), \
+	_cfg(U32, roam_process_timeout), \
 	_cfg(I32, roam_scan_snr), \
 	_cfg(U32, roam_scan_tries), \
 	_cfg(U32, roam_scan_interval), \
@@ -281,6 +282,8 @@ void usteer_dump_node(struct blob_buf *buf, struct usteer_node *node)
 	blobmsg_add_u32(buf, "noise", node->noise);
 	blobmsg_add_u32(buf, "load", node->load);
 	blobmsg_add_u32(buf, "max_assoc", node->max_assoc);
+	blobmsg_add_u32(buf, "roam_source", node->roam_source);
+	blobmsg_add_u32(buf, "roam_destination", node->roam_destination);
 	if (node->rrm_nr)
 		blobmsg_add_field(buf, BLOBMSG_TYPE_ARRAY, "rrm_nr",
 				  blobmsg_data(node->rrm_nr),

usteer.h

@@ -87,6 +87,9 @@ struct usteer_node {
 	int n_assoc;
 	int max_assoc;
 	int load;
+
+	int roam_source;
+	int roam_destination;
 };
 
 struct usteer_scan_request {
@@ -160,6 +163,8 @@ struct usteer_config {
 	uint32_t signal_diff_threshold;
 
 	int32_t roam_scan_snr;
+	uint32_t roam_process_timeout;
+
 	uint32_t roam_scan_tries;
 	uint32_t roam_scan_interval;