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Antonio Quartulli
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batman-adv: Distributed ARP Table - create DHT helper functions
Add all the relevant functions in order to manage a Distributed Hash Table over the B.A.T.M.A.N.-adv network. It will later be used to store several ARP entries and implement DAT (Distributed ARP Table) Signed-off-by: Antonio Quartulli <[email protected]>
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‎net/batman-adv/Makefile

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Original file line numberDiff line numberDiff line change
@@ -23,6 +23,7 @@ batman-adv-y += bat_iv_ogm.o
2323
batman-adv-y += bitarray.o
2424
batman-adv-$(CONFIG_BATMAN_ADV_BLA) += bridge_loop_avoidance.o
2525
batman-adv-y += debugfs.o
26+
batman-adv-y += distributed-arp-table.o
2627
batman-adv-y += gateway_client.o
2728
batman-adv-y += gateway_common.o
2829
batman-adv-y += hard-interface.o

‎net/batman-adv/distributed-arp-table.c

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@@ -0,0 +1,270 @@
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/* Copyright (C) 2011-2012 B.A.T.M.A.N. contributors:
2+
*
3+
* Antonio Quartulli
4+
*
5+
* This program is free software; you can redistribute it and/or
6+
* modify it under the terms of version 2 of the GNU General Public
7+
* License as published by the Free Software Foundation.
8+
*
9+
* This program is distributed in the hope that it will be useful, but
10+
* WITHOUT ANY WARRANTY; without even the implied warranty of
11+
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12+
* General Public License for more details.
13+
*
14+
* You should have received a copy of the GNU General Public License
15+
* along with this program; if not, write to the Free Software
16+
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA
18+
*/
19+
20+
#include <linux/if_ether.h>
21+
#include <linux/if_arp.h>
22+
23+
#include "main.h"
24+
#include "distributed-arp-table.h"
25+
#include "hard-interface.h"
26+
#include "originator.h"
27+
#include "send.h"
28+
#include "types.h"
29+
#include "unicast.h"
30+
31+
/**
32+
* batadv_hash_dat - compute the hash value for an IP address
33+
* @data: data to hash
34+
* @size: size of the hash table
35+
*
36+
* Returns the selected index in the hash table for the given data
37+
*/
38+
static uint32_t batadv_hash_dat(const void *data, uint32_t size)
39+
{
40+
const unsigned char *key = data;
41+
uint32_t hash = 0;
42+
size_t i;
43+
44+
for (i = 0; i < 4; i++) {
45+
hash += key[i];
46+
hash += (hash << 10);
47+
hash ^= (hash >> 6);
48+
}
49+
50+
hash += (hash << 3);
51+
hash ^= (hash >> 11);
52+
hash += (hash << 15);
53+
54+
return hash % size;
55+
}
56+
57+
/**
58+
* batadv_is_orig_node_eligible - check whether a node can be a DHT candidate
59+
* @res: the array with the already selected candidates
60+
* @select: number of already selected candidates
61+
* @tmp_max: address of the currently evaluated node
62+
* @max: current round max address
63+
* @last_max: address of the last selected candidate
64+
* @candidate: orig_node under evaluation
65+
* @max_orig_node: last selected candidate
66+
*
67+
* Returns true if the node has been elected as next candidate or false othrwise
68+
*/
69+
static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
70+
int select, batadv_dat_addr_t tmp_max,
71+
batadv_dat_addr_t max,
72+
batadv_dat_addr_t last_max,
73+
struct batadv_orig_node *candidate,
74+
struct batadv_orig_node *max_orig_node)
75+
{
76+
bool ret = false;
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int j;
78+
79+
/* Check if this node has already been selected... */
80+
for (j = 0; j < select; j++)
81+
if (res[j].orig_node == candidate)
82+
break;
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/* ..and possibly skip it */
84+
if (j < select)
85+
goto out;
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/* sanity check: has it already been selected? This should not happen */
87+
if (tmp_max > last_max)
88+
goto out;
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/* check if during this iteration an originator with a closer dht
90+
* address has already been found
91+
*/
92+
if (tmp_max < max)
93+
goto out;
94+
/* this is an hash collision with the temporary selected node. Choose
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* the one with the lowest address
96+
*/
97+
if ((tmp_max == max) &&
98+
(batadv_compare_eth(candidate->orig, max_orig_node->orig) > 0))
99+
goto out;
100+
101+
ret = true;
102+
out:
103+
return ret;
104+
}
105+
106+
/**
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* batadv_choose_next_candidate - select the next DHT candidate
108+
* @bat_priv: the bat priv with all the soft interface information
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* @cands: candidates array
110+
* @select: number of candidates already present in the array
111+
* @ip_key: key to look up in the DHT
112+
* @last_max: pointer where the address of the selected candidate will be saved
113+
*/
114+
static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
115+
struct batadv_dat_candidate *cands,
116+
int select, batadv_dat_addr_t ip_key,
117+
batadv_dat_addr_t *last_max)
118+
{
119+
batadv_dat_addr_t max = 0, tmp_max = 0;
120+
struct batadv_orig_node *orig_node, *max_orig_node = NULL;
121+
struct batadv_hashtable *hash = bat_priv->orig_hash;
122+
struct hlist_node *node;
123+
struct hlist_head *head;
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int i;
125+
126+
/* if no node is eligible as candidate, leave the candidate type as
127+
* NOT_FOUND
128+
*/
129+
cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
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131+
/* iterate over the originator list and find the node with closest
132+
* dat_address which has not been selected yet
133+
*/
134+
for (i = 0; i < hash->size; i++) {
135+
head = &hash->table[i];
136+
137+
rcu_read_lock();
138+
hlist_for_each_entry_rcu(orig_node, node, head, hash_entry) {
139+
/* the dht space is a ring and addresses are unsigned */
140+
tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
141+
ip_key;
142+
143+
if (!batadv_is_orig_node_eligible(cands, select,
144+
tmp_max, max,
145+
*last_max, orig_node,
146+
max_orig_node))
147+
continue;
148+
149+
if (!atomic_inc_not_zero(&orig_node->refcount))
150+
continue;
151+
152+
max = tmp_max;
153+
if (max_orig_node)
154+
batadv_orig_node_free_ref(max_orig_node);
155+
max_orig_node = orig_node;
156+
}
157+
rcu_read_unlock();
158+
}
159+
if (max_orig_node) {
160+
cands[select].type = BATADV_DAT_CANDIDATE_ORIG;
161+
cands[select].orig_node = max_orig_node;
162+
batadv_dbg(BATADV_DBG_DAT, bat_priv,
163+
"dat_select_candidates() %d: selected %pM addr=%u dist=%u\n",
164+
select, max_orig_node->orig, max_orig_node->dat_addr,
165+
max);
166+
}
167+
*last_max = max;
168+
}
169+
170+
/**
171+
* batadv_dat_select_candidates - selects the nodes which the DHT message has to
172+
* be sent to
173+
* @bat_priv: the bat priv with all the soft interface information
174+
* @ip_dst: ipv4 to look up in the DHT
175+
*
176+
* An originator O is selected if and only if its DHT_ID value is one of three
177+
* closest values (from the LEFT, with wrap around if needed) then the hash
178+
* value of the key. ip_dst is the key.
179+
*
180+
* Returns the candidate array of size BATADV_DAT_CANDIDATE_NUM
181+
*/
182+
static struct batadv_dat_candidate *
183+
batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst)
184+
{
185+
int select;
186+
batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
187+
struct batadv_dat_candidate *res;
188+
189+
if (!bat_priv->orig_hash)
190+
return NULL;
191+
192+
res = kmalloc(BATADV_DAT_CANDIDATES_NUM * sizeof(*res), GFP_ATOMIC);
193+
if (!res)
194+
return NULL;
195+
196+
ip_key = (batadv_dat_addr_t)batadv_hash_dat(&ip_dst,
197+
BATADV_DAT_ADDR_MAX);
198+
199+
batadv_dbg(BATADV_DBG_DAT, bat_priv,
200+
"dat_select_candidates(): IP=%pI4 hash(IP)=%u\n", &ip_dst,
201+
ip_key);
202+
203+
for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
204+
batadv_choose_next_candidate(bat_priv, res, select, ip_key,
205+
&last_max);
206+
207+
return res;
208+
}
209+
210+
/**
211+
* batadv_dat_send_data - send a payload to the selected candidates
212+
* @bat_priv: the bat priv with all the soft interface information
213+
* @skb: payload to send
214+
* @ip: the DHT key
215+
* @packet_subtype: unicast4addr packet subtype to use
216+
*
217+
* In this function the skb is copied by means of pskb_copy() and is sent as
218+
* unicast packet to each of the selected candidates
219+
*
220+
* Returns true if the packet is sent to at least one candidate, false otherwise
221+
*/
222+
static bool batadv_dat_send_data(struct batadv_priv *bat_priv,
223+
struct sk_buff *skb, __be32 ip,
224+
int packet_subtype)
225+
{
226+
int i;
227+
bool ret = false;
228+
int send_status;
229+
struct batadv_neigh_node *neigh_node = NULL;
230+
struct sk_buff *tmp_skb;
231+
struct batadv_dat_candidate *cand;
232+
233+
cand = batadv_dat_select_candidates(bat_priv, ip);
234+
if (!cand)
235+
goto out;
236+
237+
batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
238+
239+
for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
240+
if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
241+
continue;
242+
243+
neigh_node = batadv_orig_node_get_router(cand[i].orig_node);
244+
if (!neigh_node)
245+
goto free_orig;
246+
247+
tmp_skb = pskb_copy(skb, GFP_ATOMIC);
248+
if (!batadv_unicast_4addr_prepare_skb(bat_priv, tmp_skb,
249+
cand[i].orig_node,
250+
packet_subtype)) {
251+
kfree_skb(tmp_skb);
252+
goto free_neigh;
253+
}
254+
255+
send_status = batadv_send_skb_packet(tmp_skb,
256+
neigh_node->if_incoming,
257+
neigh_node->addr);
258+
if (send_status == NET_XMIT_SUCCESS)
259+
/* packet sent to a candidate: return true */
260+
ret = true;
261+
free_neigh:
262+
batadv_neigh_node_free_ref(neigh_node);
263+
free_orig:
264+
batadv_orig_node_free_ref(cand[i].orig_node);
265+
}
266+
267+
out:
268+
kfree(cand);
269+
return ret;
270+
}

‎net/batman-adv/distributed-arp-table.h

Lines changed: 58 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,58 @@
1+
/* Copyright (C) 2011-2012 B.A.T.M.A.N. contributors:
2+
*
3+
* Antonio Quartulli
4+
*
5+
* This program is free software; you can redistribute it and/or
6+
* modify it under the terms of version 2 of the GNU General Public
7+
* License as published by the Free Software Foundation.
8+
*
9+
* This program is distributed in the hope that it will be useful, but
10+
* WITHOUT ANY WARRANTY; without even the implied warranty of
11+
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12+
* General Public License for more details.
13+
*
14+
* You should have received a copy of the GNU General Public License
15+
* along with this program; if not, write to the Free Software
16+
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17+
* 02110-1301, USA
18+
*/
19+
20+
#ifndef _NET_BATMAN_ADV_ARP_H_
21+
#define _NET_BATMAN_ADV_ARP_H_
22+
23+
#include "types.h"
24+
#include "originator.h"
25+
26+
#define BATADV_DAT_ADDR_MAX ((batadv_dat_addr_t)~(batadv_dat_addr_t)0)
27+
28+
/**
29+
* batadv_dat_init_orig_node_addr - assign a DAT address to the orig_node
30+
* @orig_node: the node to assign the DAT address to
31+
*/
32+
static inline void
33+
batadv_dat_init_orig_node_addr(struct batadv_orig_node *orig_node)
34+
{
35+
uint32_t addr;
36+
37+
addr = batadv_choose_orig(orig_node->orig, BATADV_DAT_ADDR_MAX);
38+
orig_node->dat_addr = (batadv_dat_addr_t)addr;
39+
}
40+
41+
/**
42+
* batadv_dat_init_own_addr - assign a DAT address to the node itself
43+
* @bat_priv: the bat priv with all the soft interface information
44+
* @primary_if: a pointer to the primary interface
45+
*/
46+
static inline void
47+
batadv_dat_init_own_addr(struct batadv_priv *bat_priv,
48+
struct batadv_hard_iface *primary_if)
49+
{
50+
uint32_t addr;
51+
52+
addr = batadv_choose_orig(primary_if->net_dev->dev_addr,
53+
BATADV_DAT_ADDR_MAX);
54+
55+
bat_priv->dat.addr = (batadv_dat_addr_t)addr;
56+
}
57+
58+
#endif /* _NET_BATMAN_ADV_ARP_H_ */

‎net/batman-adv/hard-interface.c

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -18,6 +18,7 @@
1818
*/
1919

2020
#include "main.h"
21+
#include "distributed-arp-table.h"
2122
#include "hard-interface.h"
2223
#include "soft-interface.h"
2324
#include "send.h"
@@ -109,6 +110,8 @@ static void batadv_primary_if_update_addr(struct batadv_priv *bat_priv,
109110
if (!primary_if)
110111
goto out;
111112

113+
batadv_dat_init_own_addr(bat_priv, primary_if);
114+
112115
skb = bat_priv->vis.my_info->skb_packet;
113116
vis_packet = (struct batadv_vis_packet *)skb->data;
114117
memcpy(vis_packet->vis_orig, primary_if->net_dev->dev_addr, ETH_ALEN);

‎net/batman-adv/main.h

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -73,6 +73,9 @@
7373

7474
#define BATADV_LOG_BUF_LEN 8192 /* has to be a power of 2 */
7575

76+
/* numbers of originator to contact for any PUT/GET DHT operation */
77+
#define BATADV_DAT_CANDIDATES_NUM 3
78+
7679
#define BATADV_VIS_INTERVAL 5000 /* 5 seconds */
7780

7881
/* how much worse secondary interfaces may be to be considered as bonding
@@ -117,6 +120,9 @@ enum batadv_uev_type {
117120

118121
#define BATADV_GW_THRESHOLD 50
119122

123+
#define BATADV_DAT_CANDIDATE_NOT_FOUND 0
124+
#define BATADV_DAT_CANDIDATE_ORIG 1
125+
120126
/* Debug Messages */
121127
#ifdef pr_fmt
122128
#undef pr_fmt

‎net/batman-adv/originator.c

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -18,6 +18,7 @@
1818
*/
1919

2020
#include "main.h"
21+
#include "distributed-arp-table.h"
2122
#include "originator.h"
2223
#include "hash.h"
2324
#include "translation-table.h"
@@ -223,6 +224,7 @@ struct batadv_orig_node *batadv_get_orig_node(struct batadv_priv *bat_priv,
223224
orig_node->tt_poss_change = false;
224225
orig_node->bat_priv = bat_priv;
225226
memcpy(orig_node->orig, addr, ETH_ALEN);
227+
batadv_dat_init_orig_node_addr(orig_node);
226228
orig_node->router = NULL;
227229
orig_node->tt_crc = 0;
228230
atomic_set(&orig_node->last_ttvn, 0);

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