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, 27 insertions, 0 deletions

diff --git a/net/batman-adv/packet.h b/net/batman-adv/packet.h
index 5e3b1026b509..aa46c2778ad8 100644
--- a/net/batman-adv/packet.h
+++ b/net/batman-adv/packet.h
@@ -249,6 +249,33 @@ struct batadv_unicast_4addr_packet {
          */
 };
 
+/**
+ * struct batadv_frag_packet - fragmented packet
+ * @header: common batman packet header with type, compatversion, and ttl
+ * @dest: final destination used when routing fragments
+ * @orig: originator of the fragment used when merging the packet
+ * @no: fragment number within this sequence
+ * @reserved: reserved byte for alignment
+ * @seqno: sequence identification
+ * @total_size: size of the merged packet
+ */
+struct batadv_frag_packet {
+        struct  batadv_header header;
+#if defined(__BIG_ENDIAN_BITFIELD)
+        uint8_t no:4;
+        uint8_t reserved:4;
+#elif defined(__LITTLE_ENDIAN_BITFIELD)
+        uint8_t reserved:4;
+        uint8_t no:4;
+#else
+#error "unknown bitfield endianess"
+#endif
+        uint8_t dest[ETH_ALEN];
+        uint8_t orig[ETH_ALEN];
+        __be16  seqno;
+        __be16  total_size;
+};
+
 struct batadv_bcast_packet {
         struct batadv_header header;
         uint8_t  reserved;