Add optional reassoc-to-same-BSS optimization

The new reassoc_same_bss_optim=1 configuration parameter can now be used
to request wpa_supplicant to bypass the unnecessary Authentication frame
exchange when reassociating back to the same BSS with which the device
is already associated. This functionality is disabled by default since
it may cause undesired interoperability issues with some APs.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

wpa_supplicant/config.c

@@ -4185,6 +4185,7 @@ static const struct global_parse_data global_fields[] = {
 	{ INT(preassoc_mac_addr), 0 },
 	{ INT(key_mgmt_offload), 0},
 	{ INT(passive_scan), 0 },
+	{ INT(reassoc_same_bss_optim), 0 },
 };
 
 #undef FUNC

wpa_supplicant/config.h

@@ -1149,6 +1149,11 @@ struct wpa_config {
 	 * (scan_ssid=1) or P2P device discovery.
 	 */
 	int passive_scan;
+
+	/**
+	 * reassoc_same_bss_optim - Whether to optimize reassoc-to-same-BSS
+	 */
+	int reassoc_same_bss_optim;
 };
 
 

wpa_supplicant/config_file.c

@@ -1233,6 +1233,10 @@ static void wpa_config_write_global(FILE *f, struct wpa_config *config)
 
 	if (config->passive_scan)
 		fprintf(f, "passive_scan=%d\n", config->passive_scan);
+
+	if (config->reassoc_same_bss_optim)
+		fprintf(f, "reassoc_same_bss_optim=%d\n",
+			config->reassoc_same_bss_optim);
 }
 
 #endif /* CONFIG_NO_CONFIG_WRITE */

wpa_supplicant/sme.c

@@ -207,6 +207,7 @@ static void sme_send_authentication(struct wpa_supplicant *wpa_s,
 	struct wpabuf *resp = NULL;
 	u8 ext_capab[18];
 	int ext_capab_len;
+	int skip_auth;
 
 	if (bss == NULL) {
 		wpa_msg(wpa_s, MSG_ERROR, "SME: No scan result available for "
@@ -215,6 +216,8 @@ static void sme_send_authentication(struct wpa_supplicant *wpa_s,
 		return;
 	}
 
+	skip_auth = wpa_s->conf->reassoc_same_bss_optim &&
+		wpa_s->reassoc_same_bss;
 	wpa_s->current_bss = bss;
 
 	os_memset(&params, 0, sizeof(params));
@@ -465,7 +468,7 @@ static void sme_send_authentication(struct wpa_supplicant *wpa_s,
 	sme_auth_handle_rrm(wpa_s, bss);
 
 #ifdef CONFIG_SAE
-	if (params.auth_alg == WPA_AUTH_ALG_SAE &&
+	if (!skip_auth && params.auth_alg == WPA_AUTH_ALG_SAE &&
 	    pmksa_cache_set_current(wpa_s->wpa, NULL, bss->bssid, ssid, 0) == 0)
 	{
 		wpa_dbg(wpa_s, MSG_DEBUG,
@@ -474,7 +477,7 @@ static void sme_send_authentication(struct wpa_supplicant *wpa_s,
 		wpa_s->sme.sae_pmksa_caching = 1;
 	}
 
-	if (params.auth_alg == WPA_AUTH_ALG_SAE) {
+	if (!skip_auth && params.auth_alg == WPA_AUTH_ALG_SAE) {
 		if (start)
 			resp = sme_auth_build_sae_commit(wpa_s, ssid,
 							 bss->bssid);
@@ -532,6 +535,15 @@ static void sme_send_authentication(struct wpa_supplicant *wpa_s,
 	}
 #endif /* CONFIG_P2P */
 
+	if (skip_auth) {
+		wpa_msg(wpa_s, MSG_DEBUG,
+			"SME: Skip authentication step on reassoc-to-same-BSS");
+		wpabuf_free(resp);
+		sme_associate(wpa_s, ssid->mode, bss->bssid, WLAN_AUTH_OPEN);
+		return;
+	}
+
+
 	wpa_s->sme.auth_alg = params.auth_alg;
 	if (wpa_drv_authenticate(wpa_s, &params) < 0) {
 		wpa_msg(wpa_s, MSG_INFO, "SME: Authentication request to the "