mac80211: Use 3-address format for mesh broadcast frames.

The 11s task group recently changed the frame mesh multicast/broadcast frame
format to use 3-address.  This was done to avoid interactions with widely
deployed lazy-WDS access points.

This patch changes the format of group addressed frames, both mesh-originated
and proxied, to use the data format defined in draft D2.08 and forward.  The
address fields used for group addressed frames is:

In 802.11 header
 ToDS:0  FromDS:1
 addr1: DA  (broadcast/multicast address)
 addr2: TA
 addr3: Mesh SA

In address extension header:
 addr4: SA  (only present if frame was proxied)

Note that this change breaks backward compatibility with earlier mesh stack
versions.

Signed-off-by: Andrey Yurovsky <andrey@cozybit.com>
Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/util.c b/net/wireless/util.c
index ba387d8..693275a 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -274,11 +274,11 @@
 	switch (ae) {
 	case 0:
 		return 6;
-	case 1:
+	case MESH_FLAGS_AE_A4:
 		return 12;
-	case 2:
+	case MESH_FLAGS_AE_A5_A6:
 		return 18;
-	case 3:
+	case (MESH_FLAGS_AE_A4 | MESH_FLAGS_AE_A5_A6):
 		return 24;
 	default:
 		return 6;
@@ -333,10 +333,18 @@
 		}
 		break;
 	case cpu_to_le16(IEEE80211_FCTL_FROMDS):
-		if (iftype != NL80211_IFTYPE_STATION ||
+		if ((iftype != NL80211_IFTYPE_STATION &&
+		    iftype != NL80211_IFTYPE_MESH_POINT) ||
 		    (is_multicast_ether_addr(dst) &&
 		     !compare_ether_addr(src, addr)))
 			return -1;
+		if (iftype == NL80211_IFTYPE_MESH_POINT) {
+			struct ieee80211s_hdr *meshdr =
+				(struct ieee80211s_hdr *) (skb->data + hdrlen);
+			hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
+			if (meshdr->flags & MESH_FLAGS_AE_A4)
+				memcpy(src, meshdr->eaddr1, ETH_ALEN);
+		}
 		break;
 	case cpu_to_le16(0):
 		if (iftype != NL80211_IFTYPE_ADHOC)