batman-adv: refine API calls for unicast transmissions of SKBs

With this patch the functions batadv_send_skb_unicast() and
batadv_send_skb_unicast_4addr() are further refined into
batadv_send_skb_via_tt(), batadv_send_skb_via_tt_4addr() and
batadv_send_skb_via_gw(). This way we avoid any "guessing" about where to send
a packet in the unicast forwarding methods and let the callers decide.

This is going to be useful for the upcoming multicast related patches in
particular.

Further, the return values were polished a little to use the more
appropriate NET_XMIT_* defines.
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Acked-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

net/batman-adv/distributed-arp-table.c

@@ -1037,13 +1037,13 @@ bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
 	 * that a node not using the 4addr packet format doesn't support it.
 	 */
 	if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
-		err = batadv_send_skb_unicast_4addr(bat_priv, skb_new,
-						    BATADV_P_DAT_CACHE_REPLY,
-						    vid);
+		err = batadv_send_skb_via_tt_4addr(bat_priv, skb_new,
+						   BATADV_P_DAT_CACHE_REPLY,
+						   vid);
 	else
-		err = batadv_send_skb_unicast(bat_priv, skb_new, vid);
+		err = batadv_send_skb_via_tt(bat_priv, skb_new, vid);
 
-	if (!err) {
+	if (err != NET_XMIT_DROP) {
 		batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
 		ret = true;
 	}

net/batman-adv/send.c

@@ -234,35 +234,31 @@ bool batadv_send_skb_prepare_unicast_4addr(struct batadv_priv *bat_priv,
 }
 
 /**
- * batadv_send_generic_unicast_skb - send an skb as unicast
+ * batadv_send_skb_unicast - encapsulate and send an skb via unicast
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: payload to send
  * @packet_type: the batman unicast packet type to use
  * @packet_subtype: the unicast 4addr packet subtype (only relevant for unicast
  *  4addr packets)
+ * @orig_node: the originator to send the packet to
  * @vid: the vid to be used to search the translation table
  *
- * Returns 1 in case of error or 0 otherwise.
+ * Wrap the given skb into a batman-adv unicast or unicast-4addr header
+ * depending on whether BATADV_UNICAST or BATADV_UNICAST_4ADDR was supplied
+ * as packet_type. Then send this frame to the given orig_node and release a
+ * reference to this orig_node.
+ *
+ * Returns NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
  */
-int batadv_send_skb_generic_unicast(struct batadv_priv *bat_priv,
-				    struct sk_buff *skb, int packet_type,
-				    int packet_subtype,
-				    unsigned short vid)
+static int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
+				   struct sk_buff *skb, int packet_type,
+				   int packet_subtype,
+				   struct batadv_orig_node *orig_node,
+				   unsigned short vid)
 {
 	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 	struct batadv_unicast_packet *unicast_packet;
-	struct batadv_orig_node *orig_node;
-	int ret = NET_RX_DROP;
-
-	/* get routing information */
-	if (is_multicast_ether_addr(ethhdr->h_dest))
-		orig_node = batadv_gw_get_selected_orig(bat_priv);
-	else
-		/* check for tt host - increases orig_node refcount.
-		 * returns NULL in case of AP isolation
-		 */
-		orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
-						     ethhdr->h_dest, vid);
+	int ret = NET_XMIT_DROP;
 
 	if (!orig_node)
 		goto out;
@@ -296,16 +292,67 @@ int batadv_send_skb_generic_unicast(struct batadv_priv *bat_priv,
 		unicast_packet->ttvn = unicast_packet->ttvn - 1;
 
 	if (batadv_send_skb_to_orig(skb, orig_node, NULL) != NET_XMIT_DROP)
-		ret = 0;
+		ret = NET_XMIT_SUCCESS;
 
 out:
 	if (orig_node)
 		batadv_orig_node_free_ref(orig_node);
-	if (ret == NET_RX_DROP)
+	if (ret == NET_XMIT_DROP)
 		kfree_skb(skb);
 	return ret;
 }
 
+/**
+ * batadv_send_skb_via_tt_generic - send an skb via TT lookup
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: payload to send
+ * @packet_type: the batman unicast packet type to use
+ * @packet_subtype: the unicast 4addr packet subtype (only relevant for unicast
+ *  4addr packets)
+ * @vid: the vid to be used to search the translation table
+ *
+ * Look up the recipient node for the destination address in the ethernet
+ * header via the translation table. Wrap the given skb into a batman-adv
+ * unicast or unicast-4addr header depending on whether BATADV_UNICAST or
+ * BATADV_UNICAST_4ADDR was supplied as packet_type. Then send this frame
+ * to the according destination node.
+ *
+ * Returns NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
+ */
+int batadv_send_skb_via_tt_generic(struct batadv_priv *bat_priv,
+				   struct sk_buff *skb, int packet_type,
+				   int packet_subtype, unsigned short vid)
+{
+	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
+	struct batadv_orig_node *orig_node;
+
+	orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
+					     ethhdr->h_dest, vid);
+	return batadv_send_skb_unicast(bat_priv, skb, packet_type,
+				       packet_subtype, orig_node, vid);
+}
+
+/**
+ * batadv_send_skb_via_gw - send an skb via gateway lookup
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: payload to send
+ * @vid: the vid to be used to search the translation table
+ *
+ * Look up the currently selected gateway. Wrap the given skb into a batman-adv
+ * unicast header and send this frame to this gateway node.
+ *
+ * Returns NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
+ */
+int batadv_send_skb_via_gw(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			   unsigned short vid)
+{
+	struct batadv_orig_node *orig_node;
+
+	orig_node = batadv_gw_get_selected_orig(bat_priv);
+	return batadv_send_skb_unicast(bat_priv, skb, BATADV_UNICAST, 0,
+				       orig_node, vid);
+}
+
 void batadv_schedule_bat_ogm(struct batadv_hard_iface *hard_iface)
 {
 	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);

net/batman-adv/send.h

@@ -38,45 +38,54 @@ bool batadv_send_skb_prepare_unicast_4addr(struct batadv_priv *bat_priv,
 					   struct sk_buff *skb,
 					   struct batadv_orig_node *orig_node,
 					   int packet_subtype);
-int batadv_send_skb_generic_unicast(struct batadv_priv *bat_priv,
-				    struct sk_buff *skb, int packet_type,
-				    int packet_subtype,
-				    unsigned short vid);
+int batadv_send_skb_via_tt_generic(struct batadv_priv *bat_priv,
+				   struct sk_buff *skb, int packet_type,
+				   int packet_subtype, unsigned short vid);
+int batadv_send_skb_via_gw(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			   unsigned short vid);
 
 /**
- * batadv_send_unicast_skb - send the skb encapsulated in a unicast packet
+ * batadv_send_skb_via_tt - send an skb via TT lookup
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the payload to send
  * @vid: the vid to be used to search the translation table
  *
- * Returns 1 in case of error or 0 otherwise.
+ * Look up the recipient node for the destination address in the ethernet
+ * header via the translation table. Wrap the given skb into a batman-adv
+ * unicast header. Then send this frame to the according destination node.
+ *
+ * Returns NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
  */
-static inline int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
-					  struct sk_buff *skb,
-					  unsigned short vid)
+static inline int batadv_send_skb_via_tt(struct batadv_priv *bat_priv,
+					 struct sk_buff *skb,
+					 unsigned short vid)
 {
-	return batadv_send_skb_generic_unicast(bat_priv, skb, BATADV_UNICAST,
-					       0, vid);
+	return batadv_send_skb_via_tt_generic(bat_priv, skb, BATADV_UNICAST, 0,
+					      vid);
 }
 
 /**
- * batadv_send_4addr_unicast_skb - send the skb encapsulated in a unicast 4addr
- *  packet
+ * batadv_send_skb_via_tt_4addr - send an skb via TT lookup
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the payload to send
  * @packet_subtype: the unicast 4addr packet subtype to use
  * @vid: the vid to be used to search the translation table
  *
- * Returns 1 in case of error or 0 otherwise.
+ * Look up the recipient node for the destination address in the ethernet
+ * header via the translation table. Wrap the given skb into a batman-adv
+ * unicast-4addr header. Then send this frame to the according destination
+ * node.
+ *
+ * Returns NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
  */
-static inline int batadv_send_skb_unicast_4addr(struct batadv_priv *bat_priv,
-						struct sk_buff *skb,
-						int packet_subtype,
-						unsigned short vid)
+static inline int batadv_send_skb_via_tt_4addr(struct batadv_priv *bat_priv,
+					       struct sk_buff *skb,
+					       int packet_subtype,
+					       unsigned short vid)
 {
-	return batadv_send_skb_generic_unicast(bat_priv, skb,
-					       BATADV_UNICAST_4ADDR,
-					       packet_subtype, vid);
+	return batadv_send_skb_via_tt_generic(bat_priv, skb,
+					      BATADV_UNICAST_4ADDR,
+					      packet_subtype, vid);
 }
 
 #endif /* _NET_BATMAN_ADV_SEND_H_ */

net/batman-adv/soft-interface.c

@@ -298,8 +298,12 @@ static int batadv_interface_tx(struct sk_buff *skb,
 
 		batadv_dat_snoop_outgoing_arp_reply(bat_priv, skb);
 
-		ret = batadv_send_skb_unicast(bat_priv, skb, vid);
-		if (ret != 0)
+		if (is_multicast_ether_addr(ethhdr->h_dest))
+			ret = batadv_send_skb_via_gw(bat_priv, skb, vid);
+		else
+			ret = batadv_send_skb_via_tt(bat_priv, skb, vid);
+
+		if (ret == NET_XMIT_DROP)
 			goto dropped_freed;
 	}