wme.c

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/*
 * Copyright 2004, Instant802 Networks, Inc.
 *
 * 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/netdevice.h>
#include <linux/skbuff.h>
#include <linux/module.h>
#include <linux/if_arp.h>
#include <linux/types.h>
#include <net/ip.h>
#include <net/pkt_sched.h>

#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "wme.h"

/* Default mapping in classifier to work with default
 * queue setup.
 */
const int ieee802_1d_to_ac[8] = {
    IEEE80211_AC_BE,
    IEEE80211_AC_BK,
    IEEE80211_AC_BK,
    IEEE80211_AC_BE,
    IEEE80211_AC_VI,
    IEEE80211_AC_VI,
    IEEE80211_AC_VO,
    IEEE80211_AC_VO
};

static int wme_downgrade_ac(struct sk_buff *skb)
{
    switch (skb->priority) {
    case 6:
    case 7:
        skb->priority = 5; /* VO -> VI */
        return 0;
    case 4:
    case 5:
        skb->priority = 3; /* VI -> BE */
        return 0;
    case 0:
    case 3:
        skb->priority = 2; /* BE -> BK */
        return 0;
    default:
        return -1;
    }
}

static u16 ieee80211_downgrade_queue(struct ieee80211_sub_if_data *sdata,
                     struct sk_buff *skb)
{
    /* in case we are a client verify acm is not set for this ac */
    while (unlikely(sdata->wmm_acm & BIT(skb->priority))) {
        if (wme_downgrade_ac(skb)) {
            /*
             * This should not really happen. The AP has marked all
             * lower ACs to require admission control which is not
             * a reasonable configuration. Allow the frame to be
             * transmitted using AC_BK as a workaround.
             */
            break;
        }
    }

    /* look up which queue to use for frames with this 1d tag */
    return ieee802_1d_to_ac[skb->priority];
}

/* Indicate which queue to use for this fully formed 802.11 frame */
u16 ieee80211_select_queue_80211(struct ieee80211_sub_if_data *sdata,
                 struct sk_buff *skb,
                 struct ieee80211_hdr *hdr)
{
    struct ieee80211_local *local = sdata->local;
    u8 *p;

    if (local->hw.queues < IEEE80211_NUM_ACS)
        return 0;

    if (!ieee80211_is_data(hdr->frame_control)) {
        skb->priority = 7;
        return ieee802_1d_to_ac[skb->priority];
    }
    if (!ieee80211_is_data_qos(hdr->frame_control)) {
        skb->priority = 0;
        return ieee802_1d_to_ac[skb->priority];
    }

    p = ieee80211_get_qos_ctl(hdr);
    skb->priority = *p & IEEE80211_QOS_CTL_TAG1D_MASK;

    return ieee80211_downgrade_queue(sdata, skb);
}

/* Indicate which queue to use. */
u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
               struct sk_buff *skb)
{
    struct ieee80211_local *local = sdata->local;
    struct sta_info *sta = NULL;
    const u8 *ra = NULL;
    bool qos = false;

    if (local->hw.queues < IEEE80211_NUM_ACS || skb->len < 6) {
        skb->priority = 0; /* required for correct WPA/11i MIC */
        return 0;
    }

    rcu_read_lock();
    switch (sdata->vif.type) {
    case NL80211_IFTYPE_AP_VLAN:
        sta = rcu_dereference(sdata->u.vlan.sta);
        if (sta) {
            qos = test_sta_flag(sta, WLAN_STA_WME);
            break;
        }
    case NL80211_IFTYPE_AP:
        ra = skb->data;
        break;
    case NL80211_IFTYPE_WDS:
        ra = sdata->u.wds.remote_addr;
        break;
#ifdef CONFIG_MAC80211_MESH
    case NL80211_IFTYPE_MESH_POINT:
        qos = true;
        break;
#endif
    case NL80211_IFTYPE_STATION:
        ra = sdata->u.mgd.bssid;
        break;
    case NL80211_IFTYPE_ADHOC:
        ra = skb->data;
        break;
    default:
        break;
    }

    if (!sta && ra && !is_multicast_ether_addr(ra)) {
        sta = sta_info_get(sdata, ra);
        if (sta)
            qos = test_sta_flag(sta, WLAN_STA_WME);
    }
    rcu_read_unlock();

    if (!qos) {
        skb->priority = 0; /* required for correct WPA/11i MIC */
        return IEEE80211_AC_BE;
    }

    /* use the data classifier to determine what 802.1d tag the
     * data frame has */
    skb->priority = cfg80211_classify8021d(skb);

    return ieee80211_downgrade_queue(sdata, skb);
}

void ieee80211_set_qos_hdr(struct ieee80211_sub_if_data *sdata,
               struct sk_buff *skb)
{
    struct ieee80211_hdr *hdr = (void *)skb->data;
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

    /* Fill in the QoS header if there is one. */
    if (ieee80211_is_data_qos(hdr->frame_control)) {
        u8 *p = ieee80211_get_qos_ctl(hdr);
        u8 ack_policy, tid;

        tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;

        /* preserve EOSP bit */
        ack_policy = *p & IEEE80211_QOS_CTL_EOSP;

        if (is_multicast_ether_addr(hdr->addr1) ||
            sdata->noack_map & BIT(tid)) {
            ack_policy |= IEEE80211_QOS_CTL_ACK_POLICY_NOACK;
            info->flags |= IEEE80211_TX_CTL_NO_ACK;
        }

        /* qos header is 2 bytes */
        *p++ = ack_policy | tid;
        *p = ieee80211_vif_is_mesh(&sdata->vif) ?
            (IEEE80211_QOS_CTL_MESH_CONTROL_PRESENT >> 8) : 0;
    }
}