mac80211: adding 802.11n essential A-MPDU addBA capability

This patch adds the capability to identify and answer an add block ACK
request.
As this series of patches only adds HT handling with no aggregations,
(A-MPDU aggregations acceptance is not obligatory according to 802.11n
draft) we are currently sending back a refusal upon this request.

Signed-off-by: Ron Rindjunsky <ron.rindjunsky@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mac80211/ieee80211_sta.c

@@ -57,6 +57,13 @@
 
 #define ERP_INFO_USE_PROTECTION BIT(1)
 
+/* mgmt header + 1 byte action code */
+#define IEEE80211_MIN_ACTION_SIZE (24 + 1)
+
+#define IEEE80211_ADDBA_PARAM_POLICY_MASK 0x0002
+#define IEEE80211_ADDBA_PARAM_TID_MASK 0x003C
+#define IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK 0xFFA0
+
 static void ieee80211_send_probe_req(struct net_device *dev, u8 *dst,
 				     u8 *ssid, size_t ssid_len);
 static struct ieee80211_sta_bss *
@@ -987,6 +994,91 @@ static void ieee80211_auth_challenge(struct net_device *dev,
 			    elems.challenge_len + 2, 1);
 }
 
+static void ieee80211_send_addba_resp(struct net_device *dev, u8 *da, u16 tid,
+					u8 dialog_token, u16 status, u16 policy,
+					u16 buf_size, u16 timeout)
+{
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_if_sta *ifsta = &sdata->u.sta;
+	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+	struct sk_buff *skb;
+	struct ieee80211_mgmt *mgmt;
+	u16 capab;
+
+	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
+	if (!skb) {
+		printk(KERN_DEBUG "%s: failed to allocate buffer "
+		       "for addba resp frame\n", dev->name);
+		return;
+	}
+
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+	mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
+	memset(mgmt, 0, 24);
+	memcpy(mgmt->da, da, ETH_ALEN);
+	memcpy(mgmt->sa, dev->dev_addr, ETH_ALEN);
+	if (sdata->type == IEEE80211_IF_TYPE_AP)
+		memcpy(mgmt->bssid, dev->dev_addr, ETH_ALEN);
+	else
+		memcpy(mgmt->bssid, ifsta->bssid, ETH_ALEN);
+	mgmt->frame_control = IEEE80211_FC(IEEE80211_FTYPE_MGMT,
+					   IEEE80211_STYPE_ACTION);
+
+	skb_put(skb, 1 + sizeof(mgmt->u.action.u.addba_resp));
+	mgmt->u.action.category = WLAN_CATEGORY_BACK;
+	mgmt->u.action.u.addba_resp.action_code = WLAN_ACTION_ADDBA_RESP;
+	mgmt->u.action.u.addba_resp.dialog_token = dialog_token;
+
+	capab = (u16)(policy << 1);	/* bit 1 aggregation policy */
+	capab |= (u16)(tid << 2); 	/* bit 5:2 TID number */
+	capab |= (u16)(buf_size << 6);	/* bit 15:6 max size of aggregation */
+
+	mgmt->u.action.u.addba_resp.capab = cpu_to_le16(capab);
+	mgmt->u.action.u.addba_resp.timeout = cpu_to_le16(timeout);
+	mgmt->u.action.u.addba_resp.status = cpu_to_le16(status);
+
+	ieee80211_sta_tx(dev, skb, 0);
+
+	return;
+}
+
+static void ieee80211_sta_process_addba_request(struct net_device *dev,
+						struct ieee80211_mgmt *mgmt,
+						size_t len)
+{
+	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+	struct sta_info *sta;
+	u16 capab, tid, timeout, ba_policy, buf_size, status;
+	u8 dialog_token;
+
+	sta = sta_info_get(local, mgmt->sa);
+	if (!sta)
+		return;
+
+	/* extract session parameters from addba request frame */
+	dialog_token = mgmt->u.action.u.addba_req.dialog_token;
+	timeout = le16_to_cpu(mgmt->u.action.u.addba_req.timeout);
+
+	capab = le16_to_cpu(mgmt->u.action.u.addba_req.capab);
+	ba_policy = (capab & IEEE80211_ADDBA_PARAM_POLICY_MASK) >> 1;
+	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
+	buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;
+
+	/* TODO - currently aggregation is declined (A-MPDU add BA request
+	* acceptance is not obligatory by 802.11n draft), but here is
+	* the entry point for dealing with it */
+#ifdef MAC80211_HT_DEBUG
+	if (net_ratelimit())
+		printk(KERN_DEBUG "Add Block Ack request arrived,"
+				   " currently denying it\n");
+#endif /* MAC80211_HT_DEBUG */
+
+	status = WLAN_STATUS_REQUEST_DECLINED;
+
+	ieee80211_send_addba_resp(sta->dev, sta->addr, tid, dialog_token,
+				status, 1, buf_size, timeout);
+	sta_info_put(sta);
+}
 
 static void ieee80211_rx_mgmt_auth(struct net_device *dev,
 				   struct ieee80211_if_sta *ifsta,
@@ -1870,6 +1962,34 @@ static void ieee80211_rx_mgmt_probe_req(struct net_device *dev,
 	ieee80211_sta_tx(dev, skb, 0);
 }
 
+void ieee80211_rx_mgmt_action(struct net_device *dev,
+			     struct ieee80211_if_sta *ifsta,
+			     struct ieee80211_mgmt *mgmt,
+			     size_t len)
+{
+	if (len < IEEE80211_MIN_ACTION_SIZE)
+		return;
+
+	switch (mgmt->u.action.category) {
+	case WLAN_CATEGORY_BACK:
+		switch (mgmt->u.action.u.addba_req.action_code) {
+		case WLAN_ACTION_ADDBA_REQ:
+			if (len < (IEEE80211_MIN_ACTION_SIZE +
+				   sizeof(mgmt->u.action.u.addba_req)))
+				break;
+			ieee80211_sta_process_addba_request(dev, mgmt, len);
+			break;
+		default:
+			if (net_ratelimit())
+			   printk(KERN_DEBUG "%s: received unsupported BACK\n",
+					dev->name);
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+}
 
 void ieee80211_sta_rx_mgmt(struct net_device *dev, struct sk_buff *skb,
 			   struct ieee80211_rx_status *rx_status)
@@ -1899,6 +2019,7 @@ void ieee80211_sta_rx_mgmt(struct net_device *dev, struct sk_buff *skb,
 	case IEEE80211_STYPE_REASSOC_RESP:
 	case IEEE80211_STYPE_DEAUTH:
 	case IEEE80211_STYPE_DISASSOC:
+	case IEEE80211_STYPE_ACTION:
 		skb_queue_tail(&ifsta->skb_queue, skb);
 		queue_work(local->hw.workqueue, &ifsta->work);
 		return;
@@ -1956,6 +2077,9 @@ static void ieee80211_sta_rx_queued_mgmt(struct net_device *dev,
 	case IEEE80211_STYPE_DISASSOC:
 		ieee80211_rx_mgmt_disassoc(dev, ifsta, mgmt, skb->len);
 		break;
+	case IEEE80211_STYPE_ACTION:
+		ieee80211_rx_mgmt_action(dev, ifsta, mgmt, skb->len);
+		break;
 	}
 
 	kfree_skb(skb);