batman-adv: improved client announcement mechanism

The client announcement mechanism informs every mesh node in the network
of any connected non-mesh client, in order to find the path towards that
client from any given point in the mesh.

The old implementation was based on the simple idea of appending a data
buffer to each OGM containing all the client MAC addresses the node is
serving. All other nodes can populate their global translation tables
(table which links client MAC addresses to node addresses) using this
MAC address buffer and linking it to the node's address contained in the
OGM. A node that wants to contact a client has to lookup the node the
client is connected to and its address in the global translation table.

It is easy to understand that this implementation suffers from several
issues:
 - big overhead (each and every OGM contains the entire list of
   connected clients)
 - high latencies for client route updates due to long OGM trip time and
   OGM losses

The new implementation addresses these issues by appending client
changes (new client joined or a client left) to the OGM instead of
filling it with all the client addresses each time. In this way nodes
can modify their global tables by means of "updates", thus reducing the
overhead within the OGMs.

To keep the entire network in sync each node maintains a translation
table version number (ttvn) and a translation table checksum. These
values are spread with the OGM to allow all the network participants to
determine whether or not they need to update their translation table
information.

When a translation table lookup is performed in order to send a packet
to a client attached to another node, the destination's ttvn is added to
the payload packet. Forwarding nodes can compare the packet's ttvn with
their destination's ttvn (this node could have a fresher information
than the source) and re-route the packet if necessary. This greatly
reduces the packet loss of clients roaming from one AP to the next.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

1 files changed, 27 insertions, 7 deletions

diff --git a/net/batman-adv/translation-table.h b/net/batman-adv/translation-table.h
index 0f2b9905cfc..51f7e3060f6 100644
--- a/net/batman-adv/translation-table.h
+++ b/net/batman-adv/translation-table.h
@@ -22,23 +22,43 @@
 #ifndef _NET_BATMAN_ADV_TRANSLATION_TABLE_H_
 #define _NET_BATMAN_ADV_TRANSLATION_TABLE_H_
 
-int tt_local_init(struct bat_priv *bat_priv);
+int tt_len(int changes_num);
+int tt_changes_fill_buffer(struct bat_priv *bat_priv,
+			   unsigned char *buff, int buff_len);
+int tt_init(struct bat_priv *bat_priv);
 void tt_local_add(struct net_device *soft_iface, const uint8_t *addr);
 void tt_local_remove(struct bat_priv *bat_priv,
 		     const uint8_t *addr, const char *message);
-int tt_local_fill_buffer(struct bat_priv *bat_priv,
-			  unsigned char *buff, int buff_len);
 int tt_local_seq_print_text(struct seq_file *seq, void *offset);
-void tt_local_free(struct bat_priv *bat_priv);
-int tt_global_init(struct bat_priv *bat_priv);
 void tt_global_add_orig(struct bat_priv *bat_priv,
 			struct orig_node *orig_node,
 			const unsigned char *tt_buff, int tt_buff_len);
+int tt_global_add(struct bat_priv *bat_priv,
+		  struct orig_node *orig_node, const unsigned char *addr,
+		  uint8_t ttvn);
 int tt_global_seq_print_text(struct seq_file *seq, void *offset);
 void tt_global_del_orig(struct bat_priv *bat_priv,
-			 struct orig_node *orig_node, const char *message);
-void tt_global_free(struct bat_priv *bat_priv);
+			struct orig_node *orig_node, const char *message);
+void tt_global_del(struct bat_priv *bat_priv,
+		   struct orig_node *orig_node, const unsigned char *addr,
+		   const char *message);
 struct orig_node *transtable_search(struct bat_priv *bat_priv,
 				    const uint8_t *addr);
+void tt_save_orig_buffer(struct bat_priv *bat_priv, struct orig_node *orig_node,
+			 const unsigned char *tt_buff, uint8_t tt_num_changes);
+uint16_t tt_local_crc(struct bat_priv *bat_priv);
+uint16_t tt_global_crc(struct bat_priv *bat_priv, struct orig_node *orig_node);
+void tt_free(struct bat_priv *bat_priv);
+int send_tt_request(struct bat_priv *bat_priv,
+		    struct orig_node *dst_orig_node, uint8_t hvn,
+		    uint16_t tt_crc, bool full_table);
+bool send_tt_response(struct bat_priv *bat_priv,
+		      struct tt_query_packet *tt_request);
+void tt_update_changes(struct bat_priv *bat_priv, struct orig_node *orig_node,
+		       uint16_t tt_num_changes, uint8_t ttvn,
+		       struct tt_change *tt_change);
+bool is_my_client(struct bat_priv *bat_priv, const uint8_t *addr);
+void handle_tt_response(struct bat_priv *bat_priv,
+			struct tt_query_packet *tt_response);
 
 #endif /* _NET_BATMAN_ADV_TRANSLATION_TABLE_H_ */