Commit 2e3c8736 authored by Luis Carlos Cobo's avatar Luis Carlos Cobo Committed by John W. Linville
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mac80211: support functions for mesh



The two important features coded in mesh.c are:

Recently Multicast Cache: in on-demand HWMP, multicast traffic is retransmitted
by every receiving node. Even though a mesh TTL counter avoids infinite loops,
it is also necessary to avoid traffic explosion by keeping a cache of multicast
mesh frame that have been received recently. With this feature, maximum number
of retransmissions of a multicast frame for the case of N nodes within the range
of each other would be N. Without it, the maximum number of retransmissions
would be in the order of N^(MESH_TTL - 1).

Code to support mesh tables.
Signed-off-by: default avatarLuis Carlos Cobo <luisca@cozybit.com>
Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent ccf80ddf
/*
* Copyright (c) 2008 open80211s Ltd.
* Authors: Luis Carlos Cobo <luisca@cozybit.com>
* Javier Cardona <javier@cozybit.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "ieee80211_i.h"
#include "mesh.h"
#define PP_OFFSET 1 /* Path Selection Protocol */
#define PM_OFFSET 5 /* Path Selection Metric */
#define CC_OFFSET 9 /* Congestion Control Mode */
#define CAPAB_OFFSET 17
#define ACCEPT_PLINKS 0x80
int mesh_allocated;
static struct kmem_cache *rm_cache;
void ieee80211s_init(void)
{
mesh_pathtbl_init();
mesh_allocated = 1;
rm_cache = kmem_cache_create("mesh_rmc", sizeof(struct rmc_entry),
0, 0, NULL);
}
void ieee80211s_stop(void)
{
mesh_pathtbl_unregister();
kmem_cache_destroy(rm_cache);
}
/**
* mesh_matches_local - check if the config of a mesh point matches ours
*
* @ie: information elements of a management frame from the mesh peer
* @dev: local mesh interface
*
* This function checks if the mesh configuration of a mesh point matches the
* local mesh configuration, i.e. if both nodes belong to the same mesh network.
*/
bool mesh_matches_local(struct ieee802_11_elems *ie, struct net_device *dev)
{
struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
struct ieee80211_if_sta *sta = &sdata->u.sta;
if (sta->mesh_id_len == ie->mesh_id_len &&
memcmp(sta->mesh_id, ie->mesh_id, ie->mesh_id_len) == 0 &&
memcmp(sta->mesh_pp_id, ie->mesh_config + PP_OFFSET, 4) == 0 &&
memcmp(sta->mesh_pm_id, ie->mesh_config + PM_OFFSET, 4) == 0 &&
memcmp(sta->mesh_cc_id, ie->mesh_config + CC_OFFSET, 4) == 0)
/*
* As support for each feature is added, check for matching
* - On mesh config capabilities
* - Power Save Support En
* - Sync support enabled
* - Sync support active
* - Sync support required from peer
* - MDA enabled
* - Power management control on fc
*/
return true;
return false;
}
/**
* mesh_peer_accepts_plinks - check if an mp is willing to establish peer links
*
* @ie: information elements of a management frame from the mesh peer
* @dev: local mesh interface
*/
bool mesh_peer_accepts_plinks(struct ieee802_11_elems *ie,
struct net_device *dev)
{
return (*(ie->mesh_config + CAPAB_OFFSET) & ACCEPT_PLINKS) != 0;
}
/**
* mesh_accept_plinks_update: update accepting_plink in local mesh beacons
*
* @dev: mesh interface in which mesh beacons are going to be updated
*/
void mesh_accept_plinks_update(struct net_device *dev)
{
struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
bool free_plinks;
/* In case mesh_plink_free_count > 0 and mesh_plinktbl_capacity == 0,
* the mesh interface might be able to establish plinks with peers that
* are already on the table but are not on ESTAB state. However, in
* general the mesh interface is not accepting peer link requests from
* new peers, and that must be reflected in the beacon
*/
free_plinks = mesh_plink_availables(sdata);
if (free_plinks != sdata->u.sta.accepting_plinks)
ieee80211_sta_timer((unsigned long) sdata);
}
void mesh_ids_set_default(struct ieee80211_if_sta *sta)
{
u8 def_id[4] = {0x00, 0x0F, 0xAC, 0xff};
memcpy(sta->mesh_pp_id, def_id, 4);
memcpy(sta->mesh_pm_id, def_id, 4);
memcpy(sta->mesh_cc_id, def_id, 4);
}
int mesh_rmc_init(struct net_device *dev)
{
struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
int i;
sdata->u.sta.rmc = kmalloc(sizeof(struct mesh_rmc), GFP_KERNEL);
if (!sdata->u.sta.rmc)
return -ENOMEM;
sdata->u.sta.rmc->idx_mask = RMC_BUCKETS - 1;
for (i = 0; i < RMC_BUCKETS; i++)
INIT_LIST_HEAD(&sdata->u.sta.rmc->bucket[i].list);
return 0;
}
void mesh_rmc_free(struct net_device *dev)
{
struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
struct mesh_rmc *rmc = sdata->u.sta.rmc;
struct rmc_entry *p, *n;
int i;
if (!sdata->u.sta.rmc)
return;
for (i = 0; i < RMC_BUCKETS; i++)
list_for_each_entry_safe(p, n, &rmc->bucket[i].list, list) {
list_del(&p->list);
kmem_cache_free(rm_cache, p);
}
kfree(rmc);
sdata->u.sta.rmc = NULL;
}
/**
* mesh_rmc_check - Check frame in recent multicast cache and add if absent.
*
* @sa: source address
* @mesh_hdr: mesh_header
*
* Returns: 0 if the frame is not in the cache, nonzero otherwise.
*
* Checks using the source address and the mesh sequence number if we have
* received this frame lately. If the frame is not in the cache, it is added to
* it.
*/
int mesh_rmc_check(u8 *sa, struct ieee80211s_hdr *mesh_hdr,
struct net_device *dev)
{
struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
struct mesh_rmc *rmc = sdata->u.sta.rmc;
u32 seqnum = 0;
int entries = 0;
u8 idx;
struct rmc_entry *p, *n;
/* Don't care about endianness since only match matters */
memcpy(&seqnum, mesh_hdr->seqnum, sizeof(mesh_hdr->seqnum));
idx = mesh_hdr->seqnum[0] & rmc->idx_mask;
list_for_each_entry_safe(p, n, &rmc->bucket[idx].list, list) {
++entries;
if (time_after(jiffies, p->exp_time) ||
(entries == RMC_QUEUE_MAX_LEN)) {
list_del(&p->list);
kmem_cache_free(rm_cache, p);
--entries;
} else if ((seqnum == p->seqnum)
&& (memcmp(sa, p->sa, ETH_ALEN) == 0))
return -1;
}
p = kmem_cache_alloc(rm_cache, GFP_ATOMIC);
if (!p) {
printk(KERN_DEBUG "o11s: could not allocate RMC entry\n");
return 0;
}
p->seqnum = seqnum;
p->exp_time = jiffies + RMC_TIMEOUT;
memcpy(p->sa, sa, ETH_ALEN);
list_add(&p->list, &rmc->bucket[idx].list);
return 0;
}
void mesh_mgmt_ies_add(struct sk_buff *skb, struct net_device *dev)
{
struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
struct ieee80211_supported_band *sband;
u8 *pos;
int len, i, rate;
sband = local->hw.wiphy->bands[local->hw.conf.channel->band];
len = sband->n_bitrates;
if (len > 8)
len = 8;
pos = skb_put(skb, len + 2);
*pos++ = WLAN_EID_SUPP_RATES;
*pos++ = len;
for (i = 0; i < len; i++) {
rate = sband->bitrates[i].bitrate;
*pos++ = (u8) (rate / 5);
}
if (sband->n_bitrates > len) {
pos = skb_put(skb, sband->n_bitrates - len + 2);
*pos++ = WLAN_EID_EXT_SUPP_RATES;
*pos++ = sband->n_bitrates - len;
for (i = len; i < sband->n_bitrates; i++) {
rate = sband->bitrates[i].bitrate;
*pos++ = (u8) (rate / 5);
}
}
pos = skb_put(skb, 2 + sdata->u.sta.mesh_id_len);
*pos++ = WLAN_EID_MESH_ID;
*pos++ = sdata->u.sta.mesh_id_len;
if (sdata->u.sta.mesh_id_len)
memcpy(pos, sdata->u.sta.mesh_id, sdata->u.sta.mesh_id_len);
pos = skb_put(skb, 21);
*pos++ = WLAN_EID_MESH_CONFIG;
*pos++ = MESH_CFG_LEN;
/* Version */
*pos++ = 1;
/* Active path selection protocol ID */
memcpy(pos, sdata->u.sta.mesh_pp_id, 4);
pos += 4;
/* Active path selection metric ID */
memcpy(pos, sdata->u.sta.mesh_pm_id, 4);
pos += 4;
/* Congestion control mode identifier */
memcpy(pos, sdata->u.sta.mesh_cc_id, 4);
pos += 4;
/* Channel precedence:
* Not running simple channel unification protocol
*/
memset(pos, 0x00, 4);
pos += 4;
/* Mesh capability */
sdata->u.sta.accepting_plinks = mesh_plink_availables(sdata);
*pos++ = sdata->u.sta.accepting_plinks ? ACCEPT_PLINKS : 0x00;
*pos++ = 0x00;
return;
}
u32 mesh_table_hash(u8 *addr, struct net_device *dev, struct mesh_table *tbl)
{
/* Use last four bytes of hw addr and interface index as hash index */
return jhash_2words(*(u32 *)(addr+2), dev->ifindex, tbl->hash_rnd)
& tbl->hash_mask;
}
u8 mesh_id_hash(u8 *mesh_id, int mesh_id_len)
{
if (!mesh_id_len)
return 1;
else if (mesh_id_len == 1)
return (u8) mesh_id[0];
else
return (u8) (mesh_id[0] + 2 * mesh_id[1]);
}
struct mesh_table *mesh_table_alloc(int size_order)
{
int i;
struct mesh_table *newtbl;
newtbl = kmalloc(sizeof(struct mesh_table), GFP_KERNEL);
if (!newtbl)
return NULL;
newtbl->hash_buckets = kzalloc(sizeof(struct hlist_head) *
(1 << size_order), GFP_KERNEL);
if (!newtbl->hash_buckets) {
kfree(newtbl);
return NULL;
}
newtbl->hashwlock = kmalloc(sizeof(spinlock_t) *
(1 << size_order), GFP_KERNEL);
if (!newtbl->hashwlock) {
kfree(newtbl->hash_buckets);
kfree(newtbl);
return NULL;
}
newtbl->size_order = size_order;
newtbl->hash_mask = (1 << size_order) - 1;
atomic_set(&newtbl->entries, 0);
get_random_bytes(&newtbl->hash_rnd,
sizeof(newtbl->hash_rnd));
for (i = 0; i <= newtbl->hash_mask; i++)
spin_lock_init(&newtbl->hashwlock[i]);
return newtbl;
}
void mesh_table_free(struct mesh_table *tbl, bool free_leafs)
{
struct hlist_head *mesh_hash;
struct hlist_node *p, *q;
int i;
mesh_hash = tbl->hash_buckets;
for (i = 0; i <= tbl->hash_mask; i++) {
spin_lock(&tbl->hashwlock[i]);
hlist_for_each_safe(p, q, &mesh_hash[i]) {
tbl->free_node(p, free_leafs);
atomic_dec(&tbl->entries);
}
spin_unlock(&tbl->hashwlock[i]);
}
kfree(tbl->hash_buckets);
kfree(tbl->hashwlock);
kfree(tbl);
}
static void ieee80211_mesh_path_timer(unsigned long data)
{
struct ieee80211_sub_if_data *sdata =
(struct ieee80211_sub_if_data *) data;
struct ieee80211_if_sta *ifsta = &sdata->u.sta;
struct ieee80211_local *local = wdev_priv(&sdata->wdev);
queue_work(local->hw.workqueue, &ifsta->work);
}
struct mesh_table *mesh_table_grow(struct mesh_table *tbl)
{
struct mesh_table *newtbl;
struct hlist_head *oldhash;
struct hlist_node *p;
int err = 0;
int i;
if (atomic_read(&tbl->entries)
< tbl->mean_chain_len * (tbl->hash_mask + 1)) {
err = -EPERM;
goto endgrow;
}
newtbl = mesh_table_alloc(tbl->size_order + 1);
if (!newtbl) {
err = -ENOMEM;
goto endgrow;
}
newtbl->free_node = tbl->free_node;
newtbl->mean_chain_len = tbl->mean_chain_len;
newtbl->copy_node = tbl->copy_node;
atomic_set(&newtbl->entries, atomic_read(&tbl->entries));
oldhash = tbl->hash_buckets;
for (i = 0; i <= tbl->hash_mask; i++)
hlist_for_each(p, &oldhash[i])
tbl->copy_node(p, newtbl);
endgrow:
if (err)
return NULL;
else
return newtbl;
}
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