linux/net/batman-adv/translation-table.h
Antonio Quartulli 3275e7cc84 batman-adv: improve unicast packet (re)routing
In case of a client X roaming from a generic node A to another node B, it is
possible that a third node C gets A's OGM but not B's. At this point in time, if
C wants to send data to X it will send a unicast packet destined to A. The
packet header will contain A's last ttvn (C got A's OGM and so it knows it).

The packet will travel towards A without being intercepted because the ttvn
contained in its header is the newest for A.

Once A will receive the packet, A's state will not report to be in a "roaming
phase" (because, after a roaming, once A sends out its OGM, all the changes are
committed and the node is considered not to be in the roaming state anymore)
and it will match the ttvn carried by the packet. Therefore there is no reason
for A to try to alter the packet's route, thus dropping the packet because the
destination client is not there anymore.

However, C is well aware that it's routing information towards the client X is
outdated as it received an OGM from A saying that the client roamed away.
Thanks to this detail, this patch introduces a small change in behaviour: as
long as C is in the state of not knowing the new location of client X it will
forward the traffic to its last known location using ttvn-1 of the destination.
By using an older ttvn node A will be forced to re-route the packet.
Intermediate nodes are also allowed to update the packet's destination as long
as they have the information about the client's new location.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
2012-05-13 19:06:38 +02:00

60 lines
2.6 KiB
C

/*
* Copyright (C) 2007-2012 B.A.T.M.A.N. contributors:
*
* Marek Lindner, Simon Wunderlich, Antonio Quartulli
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*
*/
#ifndef _NET_BATMAN_ADV_TRANSLATION_TABLE_H_
#define _NET_BATMAN_ADV_TRANSLATION_TABLE_H_
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,
int ifindex);
void tt_local_remove(struct bat_priv *bat_priv,
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, bool roaming,
bool wifi);
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);
struct orig_node *transtable_search(struct bat_priv *bat_priv,
const uint8_t *src, const uint8_t *addr);
uint16_t tt_local_crc(struct bat_priv *bat_priv);
void tt_free(struct bat_priv *bat_priv);
bool send_tt_response(struct bat_priv *bat_priv,
struct tt_query_packet *tt_request);
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 tt_commit_changes(struct bat_priv *bat_priv);
bool is_ap_isolated(struct bat_priv *bat_priv, uint8_t *src, uint8_t *dst);
void tt_update_orig(struct bat_priv *bat_priv, struct orig_node *orig_node,
const unsigned char *tt_buff, uint8_t tt_num_changes,
uint8_t ttvn, uint16_t tt_crc);
bool tt_global_client_is_roaming(struct bat_priv *bat_priv, uint8_t *addr);
#endif /* _NET_BATMAN_ADV_TRANSLATION_TABLE_H_ */