GAS: Send error response if no room for pending dialog context

Instead of silently dropping the response that requires fragmentation,
send an error response to the station to make it aware that no full
response will be available.

Signed-off-by: Jouni Malinen <j@w1.fi>

src/ap/gas_serv.c

@@ -989,14 +989,17 @@ static void gas_serv_req_local_processing(struct hostapd_data *hapd,
 				   "for " MACSTR " (dialog token %u)",
 				   MAC2STR(sa), dialog_token);
 			wpabuf_free(buf);
-			return;
+			tx_buf = gas_anqp_build_initial_resp_buf(
+				dialog_token, WLAN_STATUS_UNSPECIFIED_FAILURE,
+				0, NULL);
+		} else {
+			di->prot = prot;
+			di->sd_resp = buf;
+			di->sd_resp_pos = 0;
+			tx_buf = gas_anqp_build_initial_resp_buf(
+				dialog_token, WLAN_STATUS_SUCCESS,
+				comeback_delay, NULL);
 		}
-		di->prot = prot;
-		di->sd_resp = buf;
-		di->sd_resp_pos = 0;
-		tx_buf = gas_anqp_build_initial_resp_buf(
-			dialog_token, WLAN_STATUS_SUCCESS, comeback_delay,
-			NULL);
 	} else {
 		wpa_printf(MSG_DEBUG, "ANQP: Initial response (no comeback)");
 		tx_buf = gas_anqp_build_initial_resp_buf(