batman-adv: use check_unicast_packet() in recv_roam_adv()

To avoid code duplication and to simplify further changes,
check_unicast_packet() is now used in recv_roam_adv() to check for not
well formed packets and so discard them.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>

net/batman-adv/routing.c

@@ -687,21 +687,8 @@ int batadv_recv_roam_adv(struct sk_buff *skb, struct batadv_hard_iface *recv_if)
 	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
 	struct batadv_roam_adv_packet *roam_adv_packet;
 	struct batadv_orig_node *orig_node;
-	struct ethhdr *ethhdr;
-
-	/* drop packet if it has not necessary minimum size */
-	if (unlikely(!pskb_may_pull(skb,
-				    sizeof(struct batadv_roam_adv_packet))))
-		goto out;
-
-	ethhdr = (struct ethhdr *)skb_mac_header(skb);
 
-	/* packet with unicast indication but broadcast recipient */
-	if (is_broadcast_ether_addr(ethhdr->h_dest))
-		goto out;
-
-	/* packet with broadcast sender address */
-	if (is_broadcast_ether_addr(ethhdr->h_source))
+	if (batadv_check_unicast_packet(skb, sizeof(*roam_adv_packet)) < 0)
 		goto out;
 
 	batadv_inc_counter(bat_priv, BATADV_CNT_TT_ROAM_ADV_RX);