wme.c

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#include "includes.h"

#include "hostapd.h"
#include "ieee802_11.h"
#include "wme.h"
#include "sta_info.h"
#include "driver_i.h"


/* TODO: maintain separate sequence and fragment numbers for each AC
 * TODO: IGMP snooping to track which multicasts to forward - and use QOS-DATA
 * if only WMM stations are receiving a certain group */


static inline u8 wmm_aci_aifsn(int aifsn, int acm, int aci)
{
        u8 ret;
        ret = (aifsn << WMM_AC_AIFNS_SHIFT) & WMM_AC_AIFSN_MASK;
        if (acm)
                ret |= WMM_AC_ACM;
        ret |= (aci << WMM_AC_ACI_SHIFT) & WMM_AC_ACI_MASK;
        return ret;
}


static inline u8 wmm_ecw(int ecwmin, int ecwmax)
{
        return ((ecwmin << WMM_AC_ECWMIN_SHIFT) & WMM_AC_ECWMIN_MASK) |
                ((ecwmax << WMM_AC_ECWMAX_SHIFT) & WMM_AC_ECWMAX_MASK);
}


/*
 * Add WMM Parameter Element to Beacon, Probe Response, and (Re)Association
 * Response frames.
 */
u8 * hostapd_eid_wmm(struct hostapd_data *hapd, u8 *eid)
{
        u8 *pos = eid;
        struct wmm_parameter_element *wmm =
                (struct wmm_parameter_element *) (pos + 2);
        int e;

        if (!hapd->conf->wmm_enabled)
                return eid;
        eid[0] = WLAN_EID_VENDOR_SPECIFIC;
        wmm->oui[0] = 0x00;
        wmm->oui[1] = 0x50;
        wmm->oui[2] = 0xf2;
        wmm->oui_type = WMM_OUI_TYPE;
        wmm->oui_subtype = WMM_OUI_SUBTYPE_PARAMETER_ELEMENT;
        wmm->version = WMM_VERSION;
        wmm->qos_info = hapd->parameter_set_count & 0xf;

        /* fill in a parameter set record for each AC */
        for (e = 0; e < 4; e++) {
                struct wmm_ac_parameter *ac = &wmm->ac[e];
                struct hostapd_wmm_ac_params *acp =
                        &hapd->iconf->wmm_ac_params[e];

                ac->aci_aifsn = wmm_aci_aifsn(acp->aifs,
                                              acp->admission_control_mandatory,
                                              e);
                ac->cw = wmm_ecw(acp->cwmin, acp->cwmax);
                ac->txop_limit = host_to_le16(acp->txop_limit);
        }

        pos = (u8 *) (wmm + 1);
        eid[1] = pos - eid - 2; /* element length */

        return pos;
}


/* This function is called when a station sends an association request with
 * WMM info element. The function returns zero on success or non-zero on any
 * error in WMM element. eid does not include Element ID and Length octets. */
int hostapd_eid_wmm_valid(struct hostapd_data *hapd, u8 *eid, size_t len)
{
        struct wmm_information_element *wmm;

        wpa_hexdump(MSG_MSGDUMP, "WMM IE", eid, len);

        if (len < sizeof(struct wmm_information_element)) {
                wpa_printf(MSG_DEBUG, "Too short WMM IE (len=%lu)",
                           (unsigned long) len);
                return -1;
        }

        wmm = (struct wmm_information_element *) eid;
        wpa_printf(MSG_DEBUG, "Validating WMM IE: OUI %02x:%02x:%02x  "
                   "OUI type %d  OUI sub-type %d  version %d  QoS info 0x%x",
                   wmm->oui[0], wmm->oui[1], wmm->oui[2], wmm->oui_type,
                   wmm->oui_subtype, wmm->version, wmm->qos_info);
        if (wmm->oui_subtype != WMM_OUI_SUBTYPE_INFORMATION_ELEMENT ||
            wmm->version != WMM_VERSION) {
                wpa_printf(MSG_DEBUG, "Unsupported WMM IE Subtype/Version");
                return -1;
        }

        return 0;
}


/* This function is called when a station sends an ACK frame for an AssocResp
 * frame (status=success) and the matching AssocReq contained a WMM element.
 */
int hostapd_wmm_sta_config(struct hostapd_data *hapd, struct sta_info *sta)
{
        /* update kernel STA data for WMM related items (WLAN_STA_WPA flag) */
        if (sta->flags & WLAN_STA_WMM)
                hostapd_sta_set_flags(hapd, sta->addr, sta->flags,
                                      WLAN_STA_WMM, ~0);
        else
                hostapd_sta_set_flags(hapd, sta->addr, sta->flags,
                                      0, ~WLAN_STA_WMM);

        return 0;
}


static void wmm_send_action(struct hostapd_data *hapd, const u8 *addr,
                            const struct wmm_tspec_element *tspec,
                            u8 action_code, u8 dialogue_token, u8 status_code)
{
        u8 buf[256];
        struct ieee80211_mgmt *m = (struct ieee80211_mgmt *) buf;
        struct wmm_tspec_element *t = (struct wmm_tspec_element *)
                m->u.action.u.wmm_action.variable;
        int len;

        hostapd_logger(hapd, addr, HOSTAPD_MODULE_IEEE80211,
                       HOSTAPD_LEVEL_DEBUG,
                       "action response - reason %d", status_code);
        os_memset(buf, 0, sizeof(buf));
        m->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
                                        WLAN_FC_STYPE_ACTION);
        os_memcpy(m->da, addr, ETH_ALEN);
        os_memcpy(m->sa, hapd->own_addr, ETH_ALEN);
        os_memcpy(m->bssid, hapd->own_addr, ETH_ALEN);
        m->u.action.category = WLAN_ACTION_WMM;
        m->u.action.u.wmm_action.action_code = action_code;
        m->u.action.u.wmm_action.dialog_token = dialogue_token;
        m->u.action.u.wmm_action.status_code = status_code;
        os_memcpy(t, tspec, sizeof(struct wmm_tspec_element));
        len = ((u8 *) (t + 1)) - buf;

        if (hostapd_send_mgmt_frame(hapd, m, len) < 0)
                perror("wmm_send_action: send");
}


int wmm_process_tspec(struct wmm_tspec_element *tspec)
{
        int medium_time, pps, duration;
        int up, psb, dir, tid;
        u16 val, surplus;

        up = (tspec->ts_info[1] >> 3) & 0x07;
        psb = (tspec->ts_info[1] >> 2) & 0x01;
        dir = (tspec->ts_info[0] >> 5) & 0x03;
        tid = (tspec->ts_info[0] >> 1) & 0x0f;
        wpa_printf(MSG_DEBUG, "WMM: TS Info: UP=%d PSB=%d Direction=%d TID=%d",
                   up, psb, dir, tid);
        val = le_to_host16(tspec->nominal_msdu_size);
        wpa_printf(MSG_DEBUG, "WMM: Nominal MSDU Size: %d%s",
                   val & 0x7fff, val & 0x8000 ? " (fixed)" : "");
        wpa_printf(MSG_DEBUG, "WMM: Mean Data Rate: %u bps",
                   le_to_host32(tspec->mean_data_rate));
        wpa_printf(MSG_DEBUG, "WMM: Minimum PHY Rate: %u bps",
                   le_to_host32(tspec->minimum_phy_rate));
        val = le_to_host16(tspec->surplus_bandwidth_allowance);
        wpa_printf(MSG_DEBUG, "WMM: Surplus Bandwidth Allowance: %u.%04u",
                   val >> 13, 10000 * (val & 0x1fff) / 0x2000);

        val = le_to_host16(tspec->nominal_msdu_size);
        if (val == 0) {
                wpa_printf(MSG_DEBUG, "WMM: Invalid Nominal MSDU Size (0)");
                return WMM_ADDTS_STATUS_INVALID_PARAMETERS;
        }
        /* pps = Ceiling((Mean Data Rate / 8) / Nominal MSDU Size) */
        pps = ((le_to_host32(tspec->mean_data_rate) / 8) + val - 1) / val;
        wpa_printf(MSG_DEBUG, "WMM: Packets-per-second estimate for TSPEC: %d",
                   pps);

        if (le_to_host32(tspec->minimum_phy_rate) < 1000000) {
                wpa_printf(MSG_DEBUG, "WMM: Too small Minimum PHY Rate");
                return WMM_ADDTS_STATUS_INVALID_PARAMETERS;
        }

        duration = (le_to_host16(tspec->nominal_msdu_size) & 0x7fff) * 8 /
                (le_to_host32(tspec->minimum_phy_rate) / 1000000) +
                50 /* FIX: proper SIFS + ACK duration */;

        /* unsigned binary number with an implicit binary point after the
         * leftmost 3 bits, i.e., 0x2000 = 1.0 */
        surplus = le_to_host16(tspec->surplus_bandwidth_allowance);
        if (surplus <= 0x2000) {
                wpa_printf(MSG_DEBUG, "WMM: Surplus Bandwidth Allowance not "
                           "greater than unity");
                return WMM_ADDTS_STATUS_INVALID_PARAMETERS;
        }

        medium_time = surplus * pps * duration / 0x2000;
        wpa_printf(MSG_DEBUG, "WMM: Estimated medium time: %u", medium_time);

        /*
         * TODO: store list of granted (and still active) TSPECs and check
         * whether there is available medium time for this request. For now,
         * just refuse requests that would by themselves take very large
         * portion of the available bandwidth.
         */
        if (medium_time > 750000) {
                wpa_printf(MSG_DEBUG, "WMM: Refuse TSPEC request for over "
                           "75%% of available bandwidth");
                return WMM_ADDTS_STATUS_REFUSED;
        }

        /* Convert to 32 microseconds per second unit */
        tspec->medium_time = host_to_le16(medium_time / 32);

        return WMM_ADDTS_STATUS_ADMISSION_ACCEPTED;
}


static void wmm_addts_req(struct hostapd_data *hapd,
                          struct ieee80211_mgmt *mgmt,
                          struct wmm_tspec_element *tspec, size_t len)
{
        u8 *end = ((u8 *) mgmt) + len;
        int res;

        if ((u8 *) (tspec + 1) > end) {
                wpa_printf(MSG_DEBUG, "WMM: TSPEC overflow in ADDTS Request");
                return;
        }

        wpa_printf(MSG_DEBUG, "WMM: ADDTS Request (Dialog Token %d) for TSPEC "
                   "from " MACSTR,
                   mgmt->u.action.u.wmm_action.dialog_token,
                   MAC2STR(mgmt->sa));

        res = wmm_process_tspec(tspec);
        wpa_printf(MSG_DEBUG, "WMM: ADDTS processing result: %d", res);

        wmm_send_action(hapd, mgmt->sa, tspec, WMM_ACTION_CODE_ADDTS_RESP,
                        mgmt->u.action.u.wmm_action.dialog_token, res);
}


void hostapd_wmm_action(struct hostapd_data *hapd, struct ieee80211_mgmt *mgmt,
                        size_t len)
{
        int action_code;
        int left = len - IEEE80211_HDRLEN - 4;
        u8 *pos = ((u8 *) mgmt) + IEEE80211_HDRLEN + 4;
        struct ieee802_11_elems elems;
        struct sta_info *sta = ap_get_sta(hapd, mgmt->sa);

        /* check that the request comes from a valid station */
        if (!sta ||
            (sta->flags & (WLAN_STA_ASSOC | WLAN_STA_WMM)) !=
            (WLAN_STA_ASSOC | WLAN_STA_WMM)) {
                hostapd_logger(hapd, mgmt->sa, HOSTAPD_MODULE_IEEE80211,
                               HOSTAPD_LEVEL_DEBUG,
                               "wmm action received is not from associated wmm"
                               " station");
                /* TODO: respond with action frame refused status code */
                return;
        }

        /* extract the tspec info element */
        if (ieee802_11_parse_elems(pos, left, &elems, 1) == ParseFailed) {
                hostapd_logger(hapd, mgmt->sa, HOSTAPD_MODULE_IEEE80211,
                               HOSTAPD_LEVEL_DEBUG,
                               "hostapd_wmm_action - could not parse wmm "
                               "action");
                /* TODO: respond with action frame invalid parameters status
                 * code */
                return;
        }

        if (!elems.wmm_tspec ||
            elems.wmm_tspec_len != (sizeof(struct wmm_tspec_element) - 2)) {
                hostapd_logger(hapd, mgmt->sa, HOSTAPD_MODULE_IEEE80211,
                               HOSTAPD_LEVEL_DEBUG,
                               "hostapd_wmm_action - missing or wrong length "
                               "tspec");
                /* TODO: respond with action frame invalid parameters status
                 * code */
                return;
        }

        /* TODO: check the request is for an AC with ACM set, if not, refuse
         * request */

        action_code = mgmt->u.action.u.wmm_action.action_code;
        switch (action_code) {
        case WMM_ACTION_CODE_ADDTS_REQ:
                wmm_addts_req(hapd, mgmt, (struct wmm_tspec_element *)
                              (elems.wmm_tspec - 2), len);
                return;
#if 0
        /* TODO: needed for client implementation */
        case WMM_ACTION_CODE_ADDTS_RESP:
                wmm_setup_request(hapd, mgmt, len);
                return;
        /* TODO: handle station teardown requests */
        case WMM_ACTION_CODE_DELTS:
                wmm_teardown(hapd, mgmt, len);
                return;
#endif
        }

        hostapd_logger(hapd, mgmt->sa, HOSTAPD_MODULE_IEEE80211,
                       HOSTAPD_LEVEL_DEBUG,
                       "hostapd_wmm_action - unknown action code %d",
                       action_code);
}