[PATCH] wpasupplicant: Only advertise MSCS and SCS in association request if supported by bss

[Sebastian Priebe]

Since version 2.10 the extended capabilities MSCS and SCS
are advertised in the association request.
This causes the assiciation request to be rejected by several
access points. Issue was observed with:
- D-Link DIR600
- Tp-Link AC1900
- Synology MR2200ac
To avoid this issue the extended capabilites MSCS and SCS
shall only be added if the bss also supports them.

Note: The extended capabilites are only included in the
association request if the bss also sent it's extended
capabilities (see wpas_populate_assoc_ies). This workaround
exists since verion 2.1.
---
--- a/wpa_supplicant/sme.c
+++ b/wpa_supplicant/sme.c
@@ -635,7 +635,7 @@
 		wpa_drv_get_ext_capa(wpa_s, WPA_IF_STATION);
 
 	ext_capab_len = wpas_build_ext_capab(wpa_s, ext_capab,
-					     sizeof(ext_capab));
+					     sizeof(ext_capab), bss);
 	if (ext_capab_len > 0) {
 		u8 *pos = wpa_s->sme.assoc_req_ie;
 		if (wpa_s->sme.assoc_req_ie_len > 0 && pos[0] == WLAN_EID_RSN)
--- a/wpa_supplicant/wpa_supplicant.c
+++ b/wpa_supplicant/wpa_supplicant.c
@@ -1881,7 +1881,7 @@
 }
 
 
-static void wpas_ext_capab_byte(struct wpa_supplicant *wpa_s, u8 *pos, int idx)
+static void wpas_ext_capab_byte(struct wpa_supplicant *wpa_s, u8 *pos, int idx, struct wpa_bss *bss)
 {
 	bool scs = true, mscs = true;
 
@@ -1932,6 +1932,8 @@
 		if (wpa_s->disable_scs_support)
 			scs = false;
 #endif /* CONFIG_TESTING_OPTIONS */
+		if (bss && !wpa_bss_ext_capab(bss, WLAN_EXT_CAPAB_SCS))
+			scs = false;
 		if (scs)
 			*pos |= 0x40; /* Bit 54 - SCS */
 		break;
@@ -1954,6 +1956,8 @@
 		if (wpa_s->disable_mscs_support)
 			mscs = false;
 #endif /* CONFIG_TESTING_OPTIONS */
+		if (bss && !wpa_bss_ext_capab(bss, WLAN_EXT_CAPAB_MSCS))
+			mscs = false;
 		if (mscs)
 			*pos |= 0x20; /* Bit 85 - Mirrored SCS */
 		break;
@@ -1961,7 +1965,7 @@
 }
 
 
-int wpas_build_ext_capab(struct wpa_supplicant *wpa_s, u8 *buf, size_t buflen)
+int wpas_build_ext_capab(struct wpa_supplicant *wpa_s, u8 *buf, size_t buflen, struct wpa_bss *bss)
 {
 	u8 *pos = buf;
 	u8 len = 11, i;
@@ -1977,7 +1981,7 @@
 	*pos++ = WLAN_EID_EXT_CAPAB;
 	*pos++ = len;
 	for (i = 0; i < len; i++, pos++) {
-		wpas_ext_capab_byte(wpa_s, pos, i);
+		wpas_ext_capab_byte(wpa_s, pos, i, bss);
 
 		if (i < wpa_s->extended_capa_len) {
 			*pos &= ~wpa_s->extended_capa_mask[i];
@@ -3145,7 +3149,7 @@
 		u8 ext_capab[18];
 		int ext_capab_len;
 		ext_capab_len = wpas_build_ext_capab(wpa_s, ext_capab,
-						     sizeof(ext_capab));
+						     sizeof(ext_capab), bss);
 		if (ext_capab_len > 0 &&
 		    wpa_ie_len + ext_capab_len <= max_wpa_ie_len) {
 			u8 *pos = wpa_ie;
--- a/wpa_supplicant/scan.c
+++ b/wpa_supplicant/scan.c
@@ -555,7 +555,7 @@
 	wpa_drv_get_ext_capa(wpa_s, type);
 
 	ext_capab_len = wpas_build_ext_capab(wpa_s, ext_capab,
-					     sizeof(ext_capab));
+					     sizeof(ext_capab), NULL);
 	if (ext_capab_len > 0 &&
 	    wpabuf_resize(&default_ies, ext_capab_len) == 0)
 		wpabuf_put_data(default_ies, ext_capab, ext_capab_len);
@@ -607,7 +607,7 @@
 		wpa_drv_get_ext_capa(wpa_s, WPA_IF_STATION);
 
 	ext_capab_len = wpas_build_ext_capab(wpa_s, ext_capab,
-					     sizeof(ext_capab));
+					     sizeof(ext_capab), NULL);
 	if (ext_capab_len > 0 &&
 	    wpabuf_resize(&extra_ie, ext_capab_len) == 0)
 		wpabuf_put_data(extra_ie, ext_capab, ext_capab_len);
--- a/wpa_supplicant/wpa_supplicant_i.h
+++ b/wpa_supplicant/wpa_supplicant_i.h
@@ -1634,7 +1634,7 @@
 		    size_t ssid_len);
 void wpas_request_connection(struct wpa_supplicant *wpa_s);
 void wpas_request_disconnection(struct wpa_supplicant *wpa_s);
-int wpas_build_ext_capab(struct wpa_supplicant *wpa_s, u8 *buf, size_t buflen);
+int wpas_build_ext_capab(struct wpa_supplicant *wpa_s, u8 *buf, size_t buflen, struct wpa_bss *bss);
 int wpas_update_random_addr(struct wpa_supplicant *wpa_s, int style);
 int wpas_update_random_addr_disassoc(struct wpa_supplicant *wpa_s);
 void add_freq(int *freqs, int *num_freqs, int freq);