GAS: Shorten the duration of the wait for GAS comeback response

When exchanging GAS frames with the AP, the initial response from the AP
may take a while to come, since the AP may need to fetch the info from a
server. The next fragments/comeback response frames should take much
less time since the AP already has all of the info, so the wait time
for these frames can be reduced.

In addition, some drivers, e.g., mac80211, try to combine ROC based flows,
to improve medium utilization. For example, if the requested ROC fits
entirely in a previous requested ROC they can be combined. Thus, reducing
the wait time for the next frames can improve medium utilization.

Shorten the duration of GAS comeback to improve medium utilization and
overall GAS exchange times.

Signed-off-by: Matti Gottlieb <matti.gottlieb@intel.com>

wpa_supplicant/gas_query.c

@@ -25,6 +25,9 @@
 /** GAS query timeout in seconds */
 #define GAS_QUERY_TIMEOUT_PERIOD 2
 
+/* GAS query wait-time / duration in ms */
+#define GAS_QUERY_WAIT_TIME_INITIAL 1000
+#define GAS_QUERY_WAIT_TIME_COMEBACK 150
 
 /**
  * struct gas_query_pending - Pending GAS query
@@ -254,9 +257,8 @@ static int pmf_in_use(struct wpa_supplicant *wpa_s, const u8 *addr)
 
 
 static int gas_query_tx(struct gas_query *gas, struct gas_query_pending *query,
-			struct wpabuf *req)
+			struct wpabuf *req, unsigned int wait_time)
 {
-	unsigned int wait_time;
 	int res, prot = pmf_in_use(gas->wpa_s, query->addr);
 
 	wpa_printf(MSG_DEBUG, "GAS: Send action frame to " MACSTR " len=%u "
@@ -267,7 +269,6 @@ static int gas_query_tx(struct gas_query *gas, struct gas_query_pending *query,
 		*categ = WLAN_ACTION_PROTECTED_DUAL;
 	}
 	os_get_reltime(&query->last_oper);
-	wait_time = 1000;
 	if (gas->wpa_s->max_remain_on_chan &&
 	    wait_time > gas->wpa_s->max_remain_on_chan)
 		wait_time = gas->wpa_s->max_remain_on_chan;
@@ -285,6 +286,7 @@ static void gas_query_tx_comeback_req(struct gas_query *gas,
 				      struct gas_query_pending *query)
 {
 	struct wpabuf *req;
+	unsigned int wait_time;
 
 	req = gas_build_comeback_req(query->dialog_token);
 	if (req == NULL) {
@@ -292,7 +294,10 @@ static void gas_query_tx_comeback_req(struct gas_query *gas,
 		return;
 	}
 
-	if (gas_query_tx(gas, query, req) < 0) {
+	wait_time = !query->offchannel_tx_started ?
+		GAS_QUERY_WAIT_TIME_INITIAL : GAS_QUERY_WAIT_TIME_COMEBACK;
+
+	if (gas_query_tx(gas, query, req, wait_time) < 0) {
 		wpa_printf(MSG_DEBUG, "GAS: Failed to send Action frame to "
 			   MACSTR, MAC2STR(query->addr));
 		gas_query_done(gas, query, GAS_QUERY_INTERNAL_ERROR);
@@ -626,7 +631,8 @@ static void gas_query_start_cb(struct wpa_radio_work *work, int deinit)
 
 	gas->work = work;
 
-	if (gas_query_tx(gas, query, query->req) < 0) {
+	if (gas_query_tx(gas, query, query->req,
+			 GAS_QUERY_WAIT_TIME_INITIAL) < 0) {
 		wpa_printf(MSG_DEBUG, "GAS: Failed to send Action frame to "
 			   MACSTR, MAC2STR(query->addr));
 		gas_query_free(query, 1);