android_kernel_samsung_msm8976/net/batman-adv/packet.h
Antonio Quartulli a73105b8d4 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>
2011-06-20 11:37:24 +02:00

203 lines
4.9 KiB
C

/*
* Copyright (C) 2007-2011 B.A.T.M.A.N. contributors:
*
* Marek Lindner, Simon Wunderlich
*
* 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_PACKET_H_
#define _NET_BATMAN_ADV_PACKET_H_
#define ETH_P_BATMAN 0x4305 /* unofficial/not registered Ethertype */
enum bat_packettype {
BAT_PACKET = 0x01,
BAT_ICMP = 0x02,
BAT_UNICAST = 0x03,
BAT_BCAST = 0x04,
BAT_VIS = 0x05,
BAT_UNICAST_FRAG = 0x06,
BAT_TT_QUERY = 0x07
};
/* this file is included by batctl which needs these defines */
#define COMPAT_VERSION 14
enum batman_flags {
PRIMARIES_FIRST_HOP = 1 << 4,
VIS_SERVER = 1 << 5,
DIRECTLINK = 1 << 6
};
/* ICMP message types */
enum icmp_packettype {
ECHO_REPLY = 0,
DESTINATION_UNREACHABLE = 3,
ECHO_REQUEST = 8,
TTL_EXCEEDED = 11,
PARAMETER_PROBLEM = 12
};
/* vis defines */
enum vis_packettype {
VIS_TYPE_SERVER_SYNC = 0,
VIS_TYPE_CLIENT_UPDATE = 1
};
/* fragmentation defines */
enum unicast_frag_flags {
UNI_FRAG_HEAD = 1 << 0,
UNI_FRAG_LARGETAIL = 1 << 1
};
/* TT_QUERY subtypes */
#define TT_QUERY_TYPE_MASK 0x3
enum tt_query_packettype {
TT_REQUEST = 0,
TT_RESPONSE = 1
};
/* TT_QUERY flags */
enum tt_query_flags {
TT_FULL_TABLE = 1 << 2
};
/* TT_CHANGE flags */
enum tt_change_flags {
TT_CHANGE_DEL = 0x01,
TT_CLIENT_ROAM = 0x02
};
struct batman_packet {
uint8_t packet_type;
uint8_t version; /* batman version field */
uint8_t ttl;
uint8_t flags; /* 0x40: DIRECTLINK flag, 0x20 VIS_SERVER flag... */
uint32_t seqno;
uint8_t orig[6];
uint8_t prev_sender[6];
uint8_t gw_flags; /* flags related to gateway class */
uint8_t tq;
uint8_t tt_num_changes;
uint8_t ttvn; /* translation table version number */
uint16_t tt_crc;
} __packed;
#define BAT_PACKET_LEN sizeof(struct batman_packet)
struct icmp_packet {
uint8_t packet_type;
uint8_t version; /* batman version field */
uint8_t ttl;
uint8_t msg_type; /* see ICMP message types above */
uint8_t dst[6];
uint8_t orig[6];
uint16_t seqno;
uint8_t uid;
uint8_t reserved;
} __packed;
#define BAT_RR_LEN 16
/* icmp_packet_rr must start with all fields from imcp_packet
* as this is assumed by code that handles ICMP packets */
struct icmp_packet_rr {
uint8_t packet_type;
uint8_t version; /* batman version field */
uint8_t ttl;
uint8_t msg_type; /* see ICMP message types above */
uint8_t dst[6];
uint8_t orig[6];
uint16_t seqno;
uint8_t uid;
uint8_t rr_cur;
uint8_t rr[BAT_RR_LEN][ETH_ALEN];
} __packed;
struct unicast_packet {
uint8_t packet_type;
uint8_t version; /* batman version field */
uint8_t ttl;
uint8_t ttvn; /* destination translation table version number */
uint8_t dest[6];
} __packed;
struct unicast_frag_packet {
uint8_t packet_type;
uint8_t version; /* batman version field */
uint8_t ttl;
uint8_t ttvn; /* destination translation table version number */
uint8_t dest[6];
uint8_t flags;
uint8_t align;
uint8_t orig[6];
uint16_t seqno;
} __packed;
struct bcast_packet {
uint8_t packet_type;
uint8_t version; /* batman version field */
uint8_t ttl;
uint8_t reserved;
uint32_t seqno;
uint8_t orig[6];
} __packed;
struct vis_packet {
uint8_t packet_type;
uint8_t version; /* batman version field */
uint8_t ttl; /* TTL */
uint8_t vis_type; /* which type of vis-participant sent this? */
uint32_t seqno; /* sequence number */
uint8_t entries; /* number of entries behind this struct */
uint8_t reserved;
uint8_t vis_orig[6]; /* originator that announces its neighbors */
uint8_t target_orig[6]; /* who should receive this packet */
uint8_t sender_orig[6]; /* who sent or rebroadcasted this packet */
} __packed;
struct tt_query_packet {
uint8_t packet_type;
uint8_t version; /* batman version field */
uint8_t ttl;
/* the flag field is a combination of:
* - TT_REQUEST or TT_RESPONSE
* - TT_FULL_TABLE */
uint8_t flags;
uint8_t dst[ETH_ALEN];
uint8_t src[ETH_ALEN];
/* the ttvn field is:
* if TT_REQUEST: ttvn that triggered the
* request
* if TT_RESPONSE: new ttvn for the src
* orig_node */
uint8_t ttvn;
/* tt_data field is:
* if TT_REQUEST: crc associated with the
* ttvn
* if TT_RESPONSE: table_size */
uint16_t tt_data;
} __packed;
struct tt_change {
uint8_t flags;
uint8_t addr[ETH_ALEN];
} __packed;
#endif /* _NET_BATMAN_ADV_PACKET_H_ */