mac80211: Fix the generation of PREQs in proactive RANN mechanism of HWMP

According to Section Y.7.4 Actions on receipt of proactive RANN, an individually
addressed PREQ should be generated towards the neighbor peer mesh STA indicated
in the RANN Sender Address field in the forwarding information.
Signed-off-by: Chun-Yeow Yeoh <yeohchunyeow@gmail.com>
Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/mesh.h

@@ -85,6 +85,8 @@ enum mesh_deferred_task_flags {
  * @state_lock: mesh path state lock used to protect changes to the
  * mpath itself.  No need to take this lock when adding or removing
  * an mpath to a hash bucket on a path table.
+ * @rann_snd_addr: the RANN sender address
+ * @is_root: the destination station of this path is a root node
  * @is_gate: the destination station of this path is a mesh gate
  *
  *
@@ -109,6 +111,8 @@ struct mesh_path {
 	u8 discovery_retries;
 	enum mesh_path_flags flags;
 	spinlock_t state_lock;
+	u8 rann_snd_addr[ETH_ALEN];
+	bool is_root;
 	bool is_gate;
 };
 

net/mac80211/mesh_hwmp.c

@@ -513,8 +513,9 @@ static void hwmp_preq_frame_process(struct ieee80211_sub_if_data *sdata,
 				    u8 *preq_elem, u32 metric)
 {
 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
-	struct mesh_path *mpath;
+	struct mesh_path *mpath = NULL;
 	u8 *target_addr, *orig_addr;
+	const u8 *da;
 	u8 target_flags, ttl;
 	u32 orig_sn, target_sn, lifetime;
 	bool reply = false;
@@ -591,9 +592,11 @@ static void hwmp_preq_frame_process(struct ieee80211_sub_if_data *sdata,
 		flags = PREQ_IE_FLAGS(preq_elem);
 		preq_id = PREQ_IE_PREQ_ID(preq_elem);
 		hopcount = PREQ_IE_HOPCOUNT(preq_elem) + 1;
+		da = (mpath && mpath->is_root) ?
+			mpath->rann_snd_addr : broadcast_addr;
 		mesh_path_sel_frame_tx(MPATH_PREQ, flags, orig_addr,
 				cpu_to_le32(orig_sn), target_flags, target_addr,
-				cpu_to_le32(target_sn), broadcast_addr,
+				cpu_to_le32(target_sn), da,
 				hopcount, ttl, cpu_to_le32(lifetime),
 				cpu_to_le32(metric), cpu_to_le32(preq_id),
 				sdata);
@@ -742,8 +745,8 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 	if (memcmp(orig_addr, sdata->vif.addr, ETH_ALEN) == 0)
 		return;
 
-	mhwmp_dbg("received RANN from %pM (is_gate=%d)", orig_addr,
-			root_is_gate);
+	mhwmp_dbg("received RANN from %pM via neighbour %pM (is_gate=%d)",
+			orig_addr, mgmt->sa, root_is_gate);
 
 	rcu_read_lock();
 	mpath = mesh_path_lookup(orig_addr, sdata);
@@ -774,6 +777,11 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 				       0, sdata);
 		mpath->sn = orig_sn;
 	}
+
+	/* Using individually addressed PREQ for root node */
+	memcpy(mpath->rann_snd_addr, mgmt->sa, ETH_ALEN);
+	mpath->is_root = true;
+
 	if (root_is_gate)
 		mesh_path_add_gate(mpath);
 
@@ -909,6 +917,7 @@ void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata)
 	struct mesh_preq_queue *preq_node;
 	struct mesh_path *mpath;
 	u8 ttl, target_flags;
+	const u8 *da;
 	u32 lifetime;
 
 	spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
@@ -971,9 +980,10 @@ void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata)
 		target_flags = MP_F_RF;
 
 	spin_unlock_bh(&mpath->state_lock);
+	da = (mpath->is_root) ? mpath->rann_snd_addr : broadcast_addr;
 	mesh_path_sel_frame_tx(MPATH_PREQ, 0, sdata->vif.addr,
 			cpu_to_le32(ifmsh->sn), target_flags, mpath->dst,
-			cpu_to_le32(mpath->sn), broadcast_addr, 0,
+			cpu_to_le32(mpath->sn), da, 0,
 			ttl, cpu_to_le32(lifetime), 0,
 			cpu_to_le32(ifmsh->preq_id++), sdata);
 	mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout);