batman-adv: Receive fragmented packets and merge

Fragments arriving at their destination are buffered for later merge.
Merged packets are passed to the main receive function as had they never
been fragmented.

Fragments are forwarded without merging if the MTU of the outgoing
interface is smaller than the size of the merged packet.

Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index fd2cdbc3ea85..a080f63b3ef6 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -28,6 +28,7 @@
 #include "bridge_loop_avoidance.h"
 #include "distributed-arp-table.h"
 #include "network-coding.h"
+#include "fragmentation.h"
 
 static int batadv_route_unicast_packet(struct sk_buff *skb,
 				       struct batadv_hard_iface *recv_if);
@@ -1013,6 +1014,64 @@ int batadv_recv_unicast_tvlv(struct sk_buff *skb,
 	return ret;
 }
 
+/**
+ * batadv_recv_frag_packet - process received fragment
+ * @skb: the received fragment
+ * @recv_if: interface that the skb is received on
+ *
+ * This function does one of the three following things: 1) Forward fragment, if
+ * the assembled packet will exceed our MTU; 2) Buffer fragment, if we till
+ * lack further fragments; 3) Merge fragments, if we have all needed parts.
+ *
+ * Return NET_RX_DROP if the skb is not consumed, NET_RX_SUCCESS otherwise.
+ */
+int batadv_recv_frag_packet(struct sk_buff *skb,
+			    struct batadv_hard_iface *recv_if)
+{
+	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
+	struct batadv_orig_node *orig_node_src = NULL;
+	struct batadv_frag_packet *frag_packet;
+	int ret = NET_RX_DROP;
+
+	if (batadv_check_unicast_packet(bat_priv, skb,
+					sizeof(*frag_packet)) < 0)
+		goto out;
+
+	frag_packet = (struct batadv_frag_packet *)skb->data;
+	orig_node_src = batadv_orig_hash_find(bat_priv, frag_packet->orig);
+	if (!orig_node_src)
+		goto out;
+
+	/* Route the fragment if it is not for us and too big to be merged. */
+	if (!batadv_is_my_mac(bat_priv, frag_packet->dest) &&
+	    batadv_frag_skb_fwd(skb, recv_if, orig_node_src)) {
+		ret = NET_RX_SUCCESS;
+		goto out;
+	}
+
+	batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_RX);
+	batadv_add_counter(bat_priv, BATADV_CNT_FRAG_RX_BYTES, skb->len);
+
+	/* Add fragment to buffer and merge if possible. */
+	if (!batadv_frag_skb_buffer(&skb, orig_node_src))
+		goto out;
+
+	/* Deliver merged packet to the appropriate handler, if it was
+	 * merged
+	 */
+	if (skb)
+		batadv_batman_skb_recv(skb, recv_if->net_dev,
+				       &recv_if->batman_adv_ptype, NULL);
+
+	ret = NET_RX_SUCCESS;
+
+out:
+	if (orig_node_src)
+		batadv_orig_node_free_ref(orig_node_src);
+
+	return ret;
+}
+
 int batadv_recv_bcast_packet(struct sk_buff *skb,
 			     struct batadv_hard_iface *recv_if)
 {