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: Luis Carlos Cobo <luisca@cozybit.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 383 insertions, 0 deletions

diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
new file mode 100644
index 000000000000..8ff533005d92
--- /dev/null
+++ b/net/mac80211/mesh.c
@@ -0,0 +1,383 @@
+/*
+ * 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;
+}