introduce WEXT scan capabilities

Introduce scan capabilities to WEXT so that userspace can do intelligent
things with scan behavior such as handling hidden SSIDs more gracefully.
If the driver reports a specific scan capability, the driver must
respect the options specified in the iw_scan_req structure when handling
the SIOCSIWSCAN call, unless it's mode or state does not allow it to do
so, in which case it must return an error.

This version switches to Dave Kilroy's suggestion of claiming unused
padding space for the scan_capa field.
Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wireless/hostap/hostap_ioctl.c

@@ -1089,6 +1089,9 @@ static int prism2_ioctl_giwrange(struct net_device *dev,
 	range->enc_capa = IW_ENC_CAPA_WPA | IW_ENC_CAPA_WPA2 |
 		IW_ENC_CAPA_CIPHER_TKIP | IW_ENC_CAPA_CIPHER_CCMP;
 
+	if (local->sta_fw_ver >= PRISM2_FW_VER(1,3,1))
+		range->scan_capa = IW_SCAN_CAPA_ESSID;
+
 	return 0;
 }
 

drivers/net/wireless/ipw2200.c

@@ -8912,6 +8912,8 @@ static int ipw_wx_get_range(struct net_device *dev,
 	range->enc_capa = IW_ENC_CAPA_WPA | IW_ENC_CAPA_WPA2 |
 		IW_ENC_CAPA_CIPHER_TKIP | IW_ENC_CAPA_CIPHER_CCMP;
 
+	range->scan_capa = IW_SCAN_CAPA_ESSID | IW_SCAN_CAPA_TYPE;
+
 	IPW_DEBUG_WX("GET Range\n");
 	return 0;
 }

include/linux/wireless.h

@@ -541,6 +541,16 @@
 /* Maximum size of returned data */
 #define IW_SCAN_MAX_DATA	4096	/* In bytes */
 
+/* Scan capability flags - in (struct iw_range *)->scan_capa */
+#define IW_SCAN_CAPA_NONE		0x00
+#define IW_SCAN_CAPA_ESSID		0x01
+#define IW_SCAN_CAPA_BSSID		0x02
+#define IW_SCAN_CAPA_CHANNEL	0x04
+#define IW_SCAN_CAPA_MODE		0x08
+#define IW_SCAN_CAPA_RATE		0x10
+#define IW_SCAN_CAPA_TYPE		0x20
+#define IW_SCAN_CAPA_TIME		0x40
+
 /* Max number of char in custom event - use multiple of them if needed */
 #define IW_CUSTOM_MAX		256	/* In bytes */
 
@@ -963,6 +973,9 @@ struct	iw_range
 	__u16		old_num_channels;
 	__u8		old_num_frequency;
 
+	/* Scan capabilities */
+	__u8		scan_capa; 	/* IW_SCAN_CAPA_* bit field */
+
 	/* Wireless event capability bitmasks */
 	__u32		event_capa[6];
 

net/mac80211/ieee80211_ioctl.c

@@ -218,6 +218,8 @@ static int ieee80211_ioctl_giwrange(struct net_device *dev,
 	IW_EVENT_CAPA_SET(range->event_capa, SIOCGIWAP);
 	IW_EVENT_CAPA_SET(range->event_capa, SIOCGIWSCAN);
 
+	range->scan_capa |= IW_SCAN_CAPA_ESSID;
+
 	return 0;
 }