FT: Explicitly check for MDE not present in non-FT association

IEEE Std 802.11-2012, 12.4.2 states that if an MDE is present in an
(Re)Association Request frame but the RSNE uses a non-FT AKM suite, the
AP shall reject the association using status code 43 ("Invalid AKMP").

wpa_validate_wpa_ie() now explicitly checks for this condition to meet
this requirement instead of simply ignoring the MDE based on non-FT AKM.

Signed-off-by: Will Glynn <will@willglynn.com>

src/ap/wpa_auth_ie.c

@@ -716,6 +716,10 @@ int wpa_validate_wpa_ie(struct wpa_authenticator *wpa_auth,
 				    "MDIE", mdie, MOBILITY_DOMAIN_ID_LEN);
 			return WPA_INVALID_MDIE;
 		}
+	} else if (mdie != NULL) {
+		wpa_printf(MSG_DEBUG,
+			   "RSN: Trying to use non-FT AKM suite, but MDIE included");
+		return WPA_INVALID_AKMP;
 	}
 #endif /* CONFIG_IEEE80211R_AP */