path: root/net/mac80211/mesh_plink.c

/*
 * Copyright (c) 2008, 2009 open80211s Ltd.
 * Author:     Luis Carlos Cobo <luisca@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 <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/random.h>
#include "ieee80211_i.h"
#include "rate.h"
#include "mesh.h"

#define PLINK_GET_LLID(p) (p + 2)
#define PLINK_GET_PLID(p) (p + 4)

#define mod_plink_timer(s, t) (mod_timer(&s->plink_timer, \
				jiffies + HZ * t / 1000))

/* We only need a valid sta if user configured a minimum rssi_threshold. */
#define rssi_threshold_check(sta, sdata) \
		(sdata->u.mesh.mshcfg.rssi_threshold == 0 ||\
		(sta && (s8) -ewma_read(&sta->avg_signal) > \
		sdata->u.mesh.mshcfg.rssi_threshold))

enum plink_event {
	PLINK_UNDEFINED,
	OPN_ACPT,
	OPN_RJCT,
	OPN_IGNR,
	CNF_ACPT,
	CNF_RJCT,
	CNF_IGNR,
	CLS_ACPT,
	CLS_IGNR
};

static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
		enum ieee80211_self_protected_actioncode action,
		u8 *da, __le16 llid, __le16 plid, __le16 reason);

/**
 * mesh_plink_fsm_restart - restart a mesh peer link finite state machine
 *
 * @sta: mesh peer link to restart
 *
 * Locking: this function must be called holding sta->lock
 */
static inline void mesh_plink_fsm_restart(struct sta_info *sta)
{
	sta->plink_state = NL80211_PLINK_LISTEN;
	sta->llid = sta->plid = sta->reason = 0;
	sta->plink_retries = 0;
}

/*
 * mesh_set_short_slot_time - enable / disable ERP short slot time.
 *
 * The standard indirectly mandates mesh STAs to turn off short slot time by
 * disallowing advertising this (802.11-2012 8.4.1.4), but that doesn't mean we
 * can't be sneaky about it. Enable short slot time if all mesh STAs in the
 * MBSS support ERP rates.
 *
 * Returns BSS_CHANGED_ERP_SLOT or 0 for no change.
 */
static u32 mesh_set_short_slot_time(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_local *local = sdata->local;
	enum ieee80211_band band = ieee80211_get_sdata_band(sdata);
	struct ieee80211_supported_band *sband = local->hw.wiphy->bands[band];
	struct sta_info *sta;
	u32 erp_rates = 0, changed = 0;
	int i;
	bool short_slot = false;

	if (band == IEEE80211_BAND_5GHZ) {
		/* (IEEE 802.11-2012 19.4.5) */
		short_slot = true;
		goto out;
	} else if (band != IEEE80211_BAND_2GHZ ||
		   (band == IEEE80211_BAND_2GHZ &&
		    local->hw.flags & IEEE80211_HW_2GHZ_SHORT_SLOT_INCAPABLE))
		goto out;

	for (i = 0; i < sband->n_bitrates; i++)
		if (sband->bitrates[i].flags & IEEE80211_RATE_ERP_G)
			erp_rates |= BIT(i);

	if (!erp_rates)
		goto out;

	rcu_read_lock();
	list_for_each_entry_rcu(sta, &local->sta_list, list) {
		if (sdata != sta->sdata ||
		    sta->plink_state != NL80211_PLINK_ESTAB)
			continue;

		short_slot = false;
		if (erp_rates & sta->sta.supp_rates[band])
			short_slot = true;
		 else
			break;
	}
	rcu_read_unlock();

out:
	if (sdata->vif.bss_conf.use_short_slot != short_slot) {
		sdata->vif.bss_conf.use_short_slot = short_slot;
		changed = BSS_CHANGED_ERP_SLOT;
		mpl_dbg(sdata, "mesh_plink %pM: ERP short slot time %d\n",
			sdata->vif.addr, short_slot);
	}
	return changed;
}

/**
 * mesh_set_ht_prot_mode - set correct HT protection mode
 *
 * Section 9.23.3.5 of IEEE 80211-2012 describes the protection rules for HT
 * mesh STA in a MBSS. Three HT protection modes are supported for now, non-HT
 * mixed mode, 20MHz-protection and no-protection mode. non-HT mixed mode is
 * selected if any non-HT peers are present in our MBSS.  20MHz-protection mode
 * is selected if all peers in our 20/40MHz MBSS support HT and atleast one
 * HT20 peer is present. Otherwise no-protection mode is selected.
 */
static u32 mesh_set_ht_prot_mode(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;
	u32 changed = 0;
	u16 ht_opmode;
	bool non_ht_sta = false, ht20_sta = false;

	if (sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_20_NOHT)
		return 0;

	rcu_read_lock();
	list_for_each_entry_rcu(sta, &local->sta_list,