batman-adv: improved roaming mechanism

With the current client announcement implementation, in case of roaming,
an update is triggered on the new AP serving the client. At that point
the new information is spread around by means of the OGM broadcasting
mechanism. Until this operations is not executed, no node is able to
correctly route traffic towards the client. This obviously causes packet
drops and introduces a delay in the time needed by the client to recover
its connections.

A new packet type called ROAMING_ADVERTISEMENT is added to account this
issue.

This message is sent in case of roaming from the new AP serving the
client to the old one and will contain the client MAC address. In this
way an out-of-OGM update is immediately committed, so that the old node
can update its global translation table. Traffic reaching this node will
then be redirected to the correct destination utilising the fresher
information. Thus reducing the packet drops and the connection recovery
delay.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/net/batman-adv/translation-table.h b/net/batman-adv/translation-table.h
index 51f7e3060f6f..1cd2d39529fe 100644
--- a/net/batman-adv/translation-table.h
+++ b/net/batman-adv/translation-table.h
@@ -28,20 +28,20 @@ int tt_changes_fill_buffer(struct bat_priv *bat_priv,
 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);
+                     const uint8_t *addr, const char *message, bool roaming);
 int tt_local_seq_print_text(struct seq_file *seq, void *offset);
 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);
+                  uint8_t ttvn, bool roaming);
 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_del(struct bat_priv *bat_priv,
                    struct orig_node *orig_node, const unsigned char *addr,
-                   const char *message);
+                   const char *message, bool roaming);
 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,
@@ -60,5 +60,7 @@ void tt_update_changes(struct bat_priv *bat_priv, struct orig_node *orig_node,
 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);
+void send_roam_adv(struct bat_priv *bat_priv, uint8_t *client,
+                   struct orig_node *orig_node);
 
 #endif /* _NET_BATMAN_ADV_TRANSLATION_TABLE_H_ */