Add configuration option for enabling optional use of short preamble

hostapd/config.c

@@ -1908,6 +1908,11 @@ struct hostapd_config * hostapd_config_read(const char *fname)
 				printf("Line %d: invalid rate list\n", line);
 				errors++;
 			}
+		} else if (os_strcmp(buf, "preamble") == 0) {
+			if (atoi(pos))
+				conf->preamble = SHORT_PREAMBLE;
+			else
+				conf->preamble = LONG_PREAMBLE;
 		} else if (os_strcmp(buf, "ignore_broadcast_ssid") == 0) {
 			bss->ignore_broadcast_ssid = atoi(pos);
 		} else if (os_strcmp(buf, "bridge_packets") == 0) {

hostapd/hostapd.conf

@@ -159,6 +159,17 @@ fragm_threshold=2346
 #basic_rates=10 20 55 110
 #basic_rates=60 120 240
 
+# Short Preamble
+# This parameter can be used to enable optional use of short preamble for
+# frames sent at 2 Mbps, 5.5 Mbps, and 11 Mbps to improve network performance.
+# This applies only to IEEE 802.11b-compatible networks and this should only be
+# enabled if the local hardware supports use of short preamble. If any of the
+# associated STAs do not support short preamble, use of short preamble will be
+# disabled (and enabled when such STAs disassociate) dynamically.
+# 0 = do not allow use of short preamble (default)
+# 1 = allow use of short preamble
+#preamble=1
+
 # Station MAC address -based authentication
 # Please note that this kind of access control requires a driver that uses
 # hostapd to take care of management frame processing and as such, this can be