mac80211: create Probe Request template

Certain type of hardware, for example wl1251 and wl1271, need a template
for the Probe Request. Create a function ieee80211_probereq_get() which
creates the template and drivers send it to hardware.
Signed-off-by: NKalle Valo <kalle.valo@nokia.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

include/net/mac80211.h

@@ -1904,6 +1904,23 @@ struct sk_buff *ieee80211_pspoll_get(struct ieee80211_hw *hw,
 struct sk_buff *ieee80211_nullfunc_get(struct ieee80211_hw *hw,
 				       struct ieee80211_vif *vif);
 
+/**
+ * ieee80211_probereq_get - retrieve a Probe Request template
+ * @hw: pointer obtained from ieee80211_alloc_hw().
+ * @vif: &struct ieee80211_vif pointer from the add_interface callback.
+ * @ssid: SSID buffer
+ * @ssid_len: length of SSID
+ * @ie: buffer containing all IEs except SSID for the template
+ * @ie_len: length of the IE buffer
+ *
+ * Creates a Probe Request template which can, for example, be uploaded to
+ * hardware.
+ */
+struct sk_buff *ieee80211_probereq_get(struct ieee80211_hw *hw,
+				       struct ieee80211_vif *vif,
+				       const u8 *ssid, size_t ssid_len,
+				       const u8 *ie, size_t ie_len);
+
 /**
  * ieee80211_rts_get - RTS frame generation function
  * @hw: pointer obtained from ieee80211_alloc_hw().

net/mac80211/tx.c

@@ -2278,6 +2278,56 @@ struct sk_buff *ieee80211_nullfunc_get(struct ieee80211_hw *hw,
 }
 EXPORT_SYMBOL(ieee80211_nullfunc_get);
 
+struct sk_buff *ieee80211_probereq_get(struct ieee80211_hw *hw,
+				       struct ieee80211_vif *vif,
+				       const u8 *ssid, size_t ssid_len,
+				       const u8 *ie, size_t ie_len)
+{
+	struct ieee80211_sub_if_data *sdata;
+	struct ieee80211_local *local;
+	struct ieee80211_hdr_3addr *hdr;
+	struct sk_buff *skb;
+	size_t ie_ssid_len;
+	u8 *pos;
+
+	sdata = vif_to_sdata(vif);
+	local = sdata->local;
+	ie_ssid_len = 2 + ssid_len;
+
+	skb = dev_alloc_skb(local->hw.extra_tx_headroom + sizeof(*hdr) +
+			    ie_ssid_len + ie_len);
+	if (!skb) {
+		printk(KERN_DEBUG "%s: failed to allocate buffer for probe "
+		       "request template\n", sdata->name);
+		return NULL;
+	}
+
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+
+	hdr = (struct ieee80211_hdr_3addr *) skb_put(skb, sizeof(*hdr));
+	memset(hdr, 0, sizeof(*hdr));
+	hdr->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
+					 IEEE80211_STYPE_PROBE_REQ);
+	memset(hdr->addr1, 0xff, ETH_ALEN);
+	memcpy(hdr->addr2, vif->addr, ETH_ALEN);
+	memset(hdr->addr3, 0xff, ETH_ALEN);
+
+	pos = skb_put(skb, ie_ssid_len);
+	*pos++ = WLAN_EID_SSID;
+	*pos++ = ssid_len;
+	if (ssid)
+		memcpy(pos, ssid, ssid_len);
+	pos += ssid_len;
+
+	if (ie) {
+		pos = skb_put(skb, ie_len);
+		memcpy(pos, ie, ie_len);
+	}
+
+	return skb;
+}
+EXPORT_SYMBOL(ieee80211_probereq_get);
+
 void ieee80211_rts_get(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		       const void *frame, size_t frame_len,
 		       const struct ieee80211_tx_info *frame_txctl,