chan.c

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/*
 * mac80211 - channel management
 */

#include <linux/nl80211.h>
#include <net/cfg80211.h>
#include "ieee80211_i.h"

static enum ieee80211_chan_mode
__ieee80211_get_channel_mode(struct ieee80211_local *local,
                 struct ieee80211_sub_if_data *ignore)
{
    struct ieee80211_sub_if_data *sdata;

    lockdep_assert_held(&local->iflist_mtx);

    list_for_each_entry(sdata, &local->interfaces, list) {
        if (sdata == ignore)
            continue;

        if (!ieee80211_sdata_running(sdata))
            continue;

        switch (sdata->vif.type) {
        case NL80211_IFTYPE_MONITOR:
            continue;
        case NL80211_IFTYPE_STATION:
            if (!sdata->u.mgd.associated)
                continue;
            break;
        case NL80211_IFTYPE_ADHOC:
            if (!sdata->u.ibss.ssid_len)
                continue;
            if (!sdata->u.ibss.fixed_channel)
                return CHAN_MODE_HOPPING;
            break;
        case NL80211_IFTYPE_AP_VLAN:
            /* will also have _AP interface */
            continue;
        case NL80211_IFTYPE_AP:
            if (!sdata->u.ap.beacon)
                continue;
            break;
        case NL80211_IFTYPE_MESH_POINT:
            if (!sdata->wdev.mesh_id_len)
                continue;
            break;
        default:
            break;
        }

        return CHAN_MODE_FIXED;
    }

    return CHAN_MODE_UNDEFINED;
}

enum ieee80211_chan_mode
ieee80211_get_channel_mode(struct ieee80211_local *local,
               struct ieee80211_sub_if_data *ignore)
{
    enum ieee80211_chan_mode mode;

    mutex_lock(&local->iflist_mtx);
    mode = __ieee80211_get_channel_mode(local, ignore);
    mutex_unlock(&local->iflist_mtx);

    return mode;
}

static enum nl80211_channel_type
ieee80211_get_superchan(struct ieee80211_local *local,
            struct ieee80211_sub_if_data *sdata)
{
    enum nl80211_channel_type superchan = NL80211_CHAN_NO_HT;
    struct ieee80211_sub_if_data *tmp;

    mutex_lock(&local->iflist_mtx);
    list_for_each_entry(tmp, &local->interfaces, list) {
        if (tmp == sdata)
            continue;

        if (!ieee80211_sdata_running(tmp))
            continue;

        switch (tmp->vif.bss_conf.channel_type) {
        case NL80211_CHAN_NO_HT:
        case NL80211_CHAN_HT20:
            if (superchan > tmp->vif.bss_conf.channel_type)
                break;

            superchan = tmp->vif.bss_conf.channel_type;
            break;
        case NL80211_CHAN_HT40PLUS:
            WARN_ON(superchan == NL80211_CHAN_HT40MINUS);
            superchan = NL80211_CHAN_HT40PLUS;
            break;
        case NL80211_CHAN_HT40MINUS:
            WARN_ON(superchan == NL80211_CHAN_HT40PLUS);
            superchan = NL80211_CHAN_HT40MINUS;
            break;
        }
    }
    mutex_unlock(&local->iflist_mtx);

    return superchan;
}

static bool
ieee80211_channel_types_are_compatible(enum nl80211_channel_type chantype1,
                       enum nl80211_channel_type chantype2,
                       enum nl80211_channel_type *compat)
{
    /*
     * start out with chantype1 being the result,
     * overwriting later if needed
     */
    if (compat)
        *compat = chantype1;

    switch (chantype1) {
    case NL80211_CHAN_NO_HT:
        if (compat)
            *compat = chantype2;
        break;
    case NL80211_CHAN_HT20:
        /*
         * allow any change that doesn't go to no-HT
         * (if it already is no-HT no change is needed)
         */
        if (chantype2 == NL80211_CHAN_NO_HT)
            break;
        if (compat)
            *compat = chantype2;
        break;
    case NL80211_CHAN_HT40PLUS:
    case NL80211_CHAN_HT40MINUS:
        /* allow smaller bandwidth and same */
        if (chantype2 == NL80211_CHAN_NO_HT)
            break;
        if (chantype2 == NL80211_CHAN_HT20)
            break;
        if (chantype2 == chantype1)
            break;
        return false;
    }

    return true;
}

bool ieee80211_set_channel_type(struct ieee80211_local *local,
                struct ieee80211_sub_if_data *sdata,
                enum nl80211_channel_type chantype)
{
    enum nl80211_channel_type superchan;
    enum nl80211_channel_type compatchan;

    superchan = ieee80211_get_superchan(local, sdata);
    if (!ieee80211_channel_types_are_compatible(superchan, chantype,
                            &compatchan))
        return false;

    local->_oper_channel_type = compatchan;

    if (sdata)
        sdata->vif.bss_conf.channel_type = chantype;

    return true;

}