mac80211: adding 802.11n essential A-MSDU Rx capability

This patch adds the ability to receive and handle A-MSDU frames.
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_i.h

@@ -155,6 +155,7 @@ struct ieee80211_txrx_data {
 			int load;
 			u32 tkip_iv32;
 			u16 tkip_iv16;
+			u8  amsdu_frame;
 		} rx;
 	} u;
 };

net/mac80211/rx.c

@@ -243,6 +243,10 @@ ieee80211_rx_h_parse_qos(struct ieee80211_txrx_data *rx)
 		u8 *qc = data + ieee80211_get_hdrlen(rx->fc) - QOS_CONTROL_LEN;
 		/* frame has qos control */
 		tid = qc[0] & QOS_CONTROL_TID_MASK;
+		if (qc[0] & IEEE80211_QOS_CONTROL_A_MSDU_PRESENT)
+			rx->u.rx.amsdu_frame = 1;
+		else
+			rx->u.rx.amsdu_frame = 0;
 	} else {
 		if (unlikely((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_MGMT)) {
 			/* Separate TID for management frames */
@@ -1196,6 +1200,125 @@ ieee80211_deliver_skb(struct ieee80211_txrx_data *rx)
 	}
 }
 
+static ieee80211_txrx_result
+ieee80211_rx_h_amsdu(struct ieee80211_txrx_data *rx)
+{
+	struct net_device *dev = rx->dev;
+	struct ieee80211_local *local = rx->local;
+	u16 fc, ethertype;
+	u8 *payload;
+	struct sk_buff *skb = rx->skb, *frame = NULL;
+	const struct ethhdr *eth;
+	int remaining, err;
+	u8 dst[ETH_ALEN];
+	u8 src[ETH_ALEN];
+	DECLARE_MAC_BUF(mac);
+
+	fc = rx->fc;
+	if (unlikely((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA))
+		return TXRX_CONTINUE;
+
+	if (unlikely(!WLAN_FC_DATA_PRESENT(fc)))
+		return TXRX_DROP;
+
+	if (!rx->u.rx.amsdu_frame)
+		return TXRX_CONTINUE;
+
+	err = ieee80211_data_to_8023(rx);
+	if (unlikely(err))
+		return TXRX_DROP;
+
+	skb->dev = dev;
+
+	dev->stats.rx_packets++;
+	dev->stats.rx_bytes += skb->len;
+
+	/* skip the wrapping header */
+	eth = (struct ethhdr *) skb_pull(skb, sizeof(struct ethhdr));
+	if (!eth)
+		return TXRX_DROP;
+
+	while (skb != frame) {
+		u8 padding;
+		__be16 len = eth->h_proto;
+		unsigned int subframe_len = sizeof(struct ethhdr) + ntohs(len);
+
+		remaining = skb->len;
+		memcpy(dst, eth->h_dest, ETH_ALEN);
+		memcpy(src, eth->h_source, ETH_ALEN);
+
+		padding = ((4 - subframe_len) & 0x3);
+		/* the last MSDU has no padding */
+		if (subframe_len > remaining) {
+			printk(KERN_DEBUG "%s: wrong buffer size", dev->name);
+			return TXRX_DROP;
+		}
+
+		skb_pull(skb, sizeof(struct ethhdr));
+		/* if last subframe reuse skb */
+		if (remaining <= subframe_len + padding)
+			frame = skb;
+		else {
+			frame = dev_alloc_skb(local->hw.extra_tx_headroom +
+					      subframe_len);
+
+			if (frame == NULL)
+				return TXRX_DROP;
+
+			skb_reserve(frame, local->hw.extra_tx_headroom +
+				    sizeof(struct ethhdr));
+			memcpy(skb_put(frame, ntohs(len)), skb->data,
+				ntohs(len));
+
+			eth = (struct ethhdr *) skb_pull(skb, ntohs(len) +
+							padding);
+			if (!eth) {
+				printk(KERN_DEBUG "%s: wrong buffer size ",
+				       dev->name);
+				dev_kfree_skb(frame);
+				return TXRX_DROP;
+			}
+		}
+
+		skb_set_network_header(frame, 0);
+		frame->dev = dev;
+		frame->priority = skb->priority;
+		rx->skb = frame;
+
+		if ((ieee80211_drop_802_1x_pae(rx, 0)) ||
+		    (ieee80211_drop_unencrypted(rx, 0))) {
+			if (skb == frame) /* last frame */
+				return TXRX_DROP;
+			dev_kfree_skb(frame);
+			continue;
+		}
+
+		payload = frame->data;
+		ethertype = (payload[6] << 8) | payload[7];
+
+		if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
+			ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
+			compare_ether_addr(payload,
+					   bridge_tunnel_header) == 0)) {
+			/* remove RFC1042 or Bridge-Tunnel
+			 * encapsulation and replace EtherType */
+			skb_pull(frame, 6);
+			memcpy(skb_push(frame, ETH_ALEN), src, ETH_ALEN);
+			memcpy(skb_push(frame, ETH_ALEN), dst, ETH_ALEN);
+		} else {
+			memcpy(skb_push(frame, sizeof(__be16)), &len,
+				sizeof(__be16));
+			memcpy(skb_push(frame, ETH_ALEN), src, ETH_ALEN);
+			memcpy(skb_push(frame, ETH_ALEN), dst, ETH_ALEN);
+		}
+
+
+		ieee80211_deliver_skb(rx);
+	}
+
+	return TXRX_QUEUED;
+}
+
 static ieee80211_txrx_result
 ieee80211_rx_h_data(struct ieee80211_txrx_data *rx)
 {
@@ -1379,6 +1502,7 @@ ieee80211_rx_handler ieee80211_rx_handlers[] =
 	 * are not passed to user space by these functions
 	 */
 	ieee80211_rx_h_remove_qos_control,
+	ieee80211_rx_h_amsdu,
 	ieee80211_rx_h_data,
 	ieee80211_rx_h_mgmt,
 	NULL