tx.c

linux 内核源代码

/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007	Jiri Benc <[e-mail]>
 * Copyright 2007	Johannes Berg <[e-mail]>
 *
 * 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.
 *
 *
 * Transmit and frame generation functions.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/etherdevice.h>
#include <linux/bitmap.h>
#include <linux/rcupdate.h>
#include <net/net_namespace.h>
#include <net/ieee80211_radiotap.h>
#include <net/cfg80211.h>
#include <net/mac80211.h>
#include <asm/unaligned.h>

#include "ieee80211_i.h"
#include "ieee80211_led.h"
#include "wep.h"
#include "wpa.h"
#include "wme.h"
#include "ieee80211_rate.h"

#define IEEE80211_TX_OK		0
#define IEEE80211_TX_AGAIN	1
#define IEEE80211_TX_FRAG_AGAIN	2

/* misc utils */

static inline void ieee80211_include_sequence(struct ieee80211_sub_if_data *sdata,
					      struct ieee80211_hdr *hdr)
{
	/* Set the sequence number for this frame. */
	hdr->seq_ctrl = cpu_to_le16(sdata->sequence);

	/* Increase the sequence number. */
	sdata->sequence = (sdata->sequence + 0x10) & IEEE80211_SCTL_SEQ;
}

#ifdef CONFIG_MAC80211_LOWTX_FRAME_DUMP
static void ieee80211_dump_frame(const char *ifname, const char *title,
				 const struct sk_buff *skb)
{
	const struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
	u16 fc;
	int hdrlen;
	DECLARE_MAC_BUF(mac);

	printk(KERN_DEBUG "%s: %s (len=%d)", ifname, title, skb->len);
	if (skb->len < 4) {
		printk("\n");
		return;
	}

	fc = le16_to_cpu(hdr->frame_control);
	hdrlen = ieee80211_get_hdrlen(fc);
	if (hdrlen > skb->len)
		hdrlen = skb->len;
	if (hdrlen >= 4)
		printk(" FC=0x%04x DUR=0x%04x",
		       fc, le16_to_cpu(hdr->duration_id));
	if (hdrlen >= 10)
		printk(" A1=%s", print_mac(mac, hdr->addr1));
	if (hdrlen >= 16)
		printk(" A2=%s", print_mac(mac, hdr->addr2));
	if (hdrlen >= 24)
		printk(" A3=%s", print_mac(mac, hdr->addr3));
	if (hdrlen >= 30)
		printk(" A4=%s", print_mac(mac, hdr->addr4));
	printk("\n");
}
#else /* CONFIG_MAC80211_LOWTX_FRAME_DUMP */
static inline void ieee80211_dump_frame(const char *ifname, const char *title,
					struct sk_buff *skb)
{
}
#endif /* CONFIG_MAC80211_LOWTX_FRAME_DUMP */

static u16 ieee80211_duration(struct ieee80211_txrx_data *tx, int group_addr,
			      int next_frag_len)
{
	int rate, mrate, erp, dur, i;
	struct ieee80211_rate *txrate = tx->u.tx.rate;
	struct ieee80211_local *local = tx->local;
	struct ieee80211_hw_mode *mode = tx->u.tx.mode;

	erp = txrate->flags & IEEE80211_RATE_ERP;

	/*
	 * data and mgmt (except PS Poll):
	 * - during CFP: 32768
	 * - during contention period:
	 *   if addr1 is group address: 0
	 *   if more fragments = 0 and addr1 is individual address: time to
	 *      transmit one ACK plus SIFS
	 *   if more fragments = 1 and addr1 is individual address: time to
	 *      transmit next fragment plus 2 x ACK plus 3 x SIFS
	 *
	 * IEEE 802.11, 9.6:
	 * - control response frame (CTS or ACK) shall be transmitted using the
	 *   same rate as the immediately previous frame in the frame exchange
	 *   sequence, if this rate belongs to the PHY mandatory rates, or else
	 *   at the highest possible rate belonging to the PHY rates in the
	 *   BSSBasicRateSet
	 */

	if ((tx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_CTL) {
		/* TODO: These control frames are not currently sent by
		 * 80211.o, but should they be implemented, this function
		 * needs to be updated to support duration field calculation.
		 *
		 * RTS: time needed to transmit pending data/mgmt frame plus
		 *    one CTS frame plus one ACK frame plus 3 x SIFS
		 * CTS: duration of immediately previous RTS minus time
		 *    required to transmit CTS and its SIFS
		 * ACK: 0 if immediately previous directed data/mgmt had
		 *    more=0, with more=1 duration in ACK frame is duration
		 *    from previous frame minus time needed to transmit ACK
		 *    and its SIFS
		 * PS Poll: BIT(15) | BIT(14) | aid
		 */
		return 0;
	}

	/* data/mgmt */
	if (0 /* FIX: data/mgmt during CFP */)
		return 32768;

	if (group_addr) /* Group address as the destination - no ACK */
		return 0;

	/* Individual destination address:
	 * IEEE 802.11, Ch. 9.6 (after IEEE 802.11g changes)
	 * CTS and ACK frames shall be transmitted using the highest rate in
	 * basic rate set that is less than or equal to the rate of the
	 * immediately previous frame and that is using the same modulation
	 * (CCK or OFDM). If no basic rate set matches with these requirements,
	 * the highest mandatory rate of the PHY that is less than or equal to
	 * the rate of the previous frame is used.
	 * Mandatory rates for IEEE 802.11g PHY: 1, 2, 5.5, 11, 6, 12, 24 Mbps
	 */
	rate = -1;
	mrate = 10; /* use 1 Mbps if everything fails */
	for (i = 0; i < mode->num_rates; i++) {
		struct ieee80211_rate *r = &mode->rates[i];
		if (r->rate > txrate->rate)
			break;

		if (IEEE80211_RATE_MODULATION(txrate->flags) !=
		    IEEE80211_RATE_MODULATION(r->flags))
			continue;

		if (r->flags & IEEE80211_RATE_BASIC)
			rate = r->rate;
		else if (r->flags & IEEE80211_RATE_MANDATORY)
			mrate = r->rate;
	}
	if (rate == -1) {
		/* No matching basic rate found; use highest suitable mandatory
		 * PHY rate */
		rate = mrate;
	}

	/* Time needed to transmit ACK
	 * (10 bytes + 4-byte FCS = 112 bits) plus SIFS; rounded up
	 * to closest integer */

	dur = ieee80211_frame_duration(local, 10, rate, erp,
		       tx->sdata->flags & IEEE80211_SDATA_SHORT_PREAMBLE);

	if (next_frag_len) {
		/* Frame is fragmented: duration increases with time needed to
		 * transmit next fragment plus ACK and 2 x SIFS. */
		dur *= 2; /* ACK + SIFS */
		/* next fragment */
		dur += ieee80211_frame_duration(local, next_frag_len,
				txrate->rate, erp,
				tx->sdata->flags &
					IEEE80211_SDATA_SHORT_PREAMBLE);
	}

	return dur;
}

static inline int __ieee80211_queue_stopped(const struct ieee80211_local *local,
					    int queue)
{
	return test_bit(IEEE80211_LINK_STATE_XOFF, &local->state[queue]);
}

static inline int __ieee80211_queue_pending(const struct ieee80211_local *local,
					    int queue)
{
	return test_bit(IEEE80211_LINK_STATE_PENDING, &local->state[queue]);
}

static int inline is_ieee80211_device(struct net_device *dev,
				      struct net_device *master)
{
	return (wdev_priv(dev->ieee80211_ptr) ==
		wdev_priv(master->ieee80211_ptr));
}

/* tx handlers */

static ieee80211_txrx_result
ieee80211_tx_h_check_assoc(struct ieee80211_txrx_data *tx)
{
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
	struct sk_buff *skb = tx->skb;
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
	u32 sta_flags;

	if (unlikely(tx->flags & IEEE80211_TXRXD_TX_INJECTED))
		return TXRX_CONTINUE;

	if (unlikely(tx->local->sta_scanning != 0) &&
	    ((tx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_MGMT ||
	     (tx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_PROBE_REQ))
		return TXRX_DROP;

	if (tx->flags & IEEE80211_TXRXD_TXPS_BUFFERED)
		return TXRX_CONTINUE;

	sta_flags = tx->sta ? tx->sta->flags : 0;

	if (likely(tx->flags & IEEE80211_TXRXD_TXUNICAST)) {
		if (unlikely(!(sta_flags & WLAN_STA_ASSOC) &&
			     tx->sdata->type != IEEE80211_IF_TYPE_IBSS &&
			     (tx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA)) {
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
			DECLARE_MAC_BUF(mac);
			printk(KERN_DEBUG "%s: dropped data frame to not "
			       "associated station %s\n",
			       tx->dev->name, print_mac(mac, hdr->addr1));
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
			I802_DEBUG_INC(tx->local->tx_handlers_drop_not_assoc);
			return TXRX_DROP;
		}
	} else {
		if (unlikely((tx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA &&
			     tx->local->num_sta == 0 &&
			     tx->sdata->type != IEEE80211_IF_TYPE_IBSS)) {
			/*
			 * No associated STAs - no need to send multicast
			 * frames.
			 */
			return TXRX_DROP;
		}
		return TXRX_CONTINUE;
	}

	if (unlikely(/* !injected && */ tx->sdata->ieee802_1x &&
		     !(sta_flags & WLAN_STA_AUTHORIZED))) {
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
		DECLARE_MAC_BUF(mac);
		printk(KERN_DEBUG "%s: dropped frame to %s"
		       " (unauthorized port)\n", tx->dev->name,
		       print_mac(mac, hdr->addr1));
#endif
		I802_DEBUG_INC(tx->local->tx_handlers_drop_unauth_port);
		return TXRX_DROP;
	}

	return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_tx_h_sequence(struct ieee80211_txrx_data *tx)
{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;

	if (ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_control)) >= 24)
		ieee80211_include_sequence(tx->sdata, hdr);

	return TXRX_CONTINUE;
}

/* This function is called whenever the AP is about to exceed the maximum limit
 * of buffered frames for power saving STAs. This situation should not really
 * happen often during normal operation, so dropping the oldest buffered packet
 * from each queue should be OK to make some room for new frames. */
static void purge_old_ps_buffers(struct ieee80211_local *local)
{
	int total = 0, purged = 0;
	struct sk_buff *skb;
	struct ieee80211_sub_if_data *sdata;
	struct sta_info *sta;

	/*
	 * virtual interfaces are protected by RCU
	 */
	rcu_read_lock();

	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
		struct ieee80211_if_ap *ap;
		if (sdata->dev == local->mdev ||
		    sdata->type != IEEE80211_IF_TYPE_AP)
			continue;
		ap = &sdata->u.ap;
		skb = skb_dequeue(&ap->ps_bc_buf);
		if (skb) {
			purged++;
			dev_kfree_skb(skb);
		}
		total += skb_queue_len(&ap->ps_bc_buf);
	}
	rcu_read_unlock();

	read_lock_bh(&local->sta_lock);
	list_for_each_entry(sta, &local->sta_list, list) {
		skb = skb_dequeue(&sta->ps_tx_buf);
		if (skb) {
			purged++;
			dev_kfree_skb(skb);
		}
		total += skb_queue_len(&sta->ps_tx_buf);
	}
	read_unlock_bh(&local->sta_lock);

	local->total_ps_buffered = total;
	printk(KERN_DEBUG "%s: PS buffers full - purged %d frames\n",
	       wiphy_name(local->hw.wiphy), purged);
}

static inline ieee80211_txrx_result
ieee80211_tx_h_multicast_ps_buf(struct ieee80211_txrx_data *tx)
{
	/* broadcast/multicast frame */
	/* If any of the associated stations is in power save mode,
	 * the frame is buffered to be sent after DTIM beacon frame */
	if ((tx->local->hw.flags & IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING) &&
	    tx->sdata->type != IEEE80211_IF_TYPE_WDS &&
	    tx->sdata->bss && atomic_read(&tx->sdata->bss->num_sta_ps) &&
	    !(tx->fc & IEEE80211_FCTL_ORDER)) {
		if (tx->local->total_ps_buffered >= TOTAL_MAX_TX_BUFFER)
			purge_old_ps_buffers(tx->local);
		if (skb_queue_len(&tx->sdata->bss->ps_bc_buf) >=
		    AP_MAX_BC_BUFFER) {
			if (net_ratelimit()) {
				printk(KERN_DEBUG "%s: BC TX buffer full - "
				       "dropping the oldest frame\n",
				       tx->dev->name);
			}
			dev_kfree_skb(skb_dequeue(&tx->sdata->bss->ps_bc_buf));
		} else
			tx->local->total_ps_buffered++;
		skb_queue_tail(&tx->sdata->bss->ps_bc_buf, tx->skb);
		return TXRX_QUEUED;
	}

	return TXRX_CONTINUE;
}

static inline ieee80211_txrx_result
ieee80211_tx_h_unicast_ps_buf(struct ieee80211_txrx_data *tx)
{
	struct sta_info *sta = tx->sta;
	DECLARE_MAC_BUF(mac);

	if (unlikely(!sta ||
		     ((tx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_MGMT &&
		      (tx->fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PROBE_RESP)))
		return TXRX_CONTINUE;

	if (unlikely((sta->flags & WLAN_STA_PS) && !sta->pspoll)) {
		struct ieee80211_tx_packet_data *pkt_data;
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
		printk(KERN_DEBUG "STA %s aid %d: PS buffer (entries "
		       "before %d)\n",
		       print_mac(mac, sta->addr), sta->aid,
		       skb_queue_len(&sta->ps_tx_buf));
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
		sta->flags |= WLAN_STA_TIM;
		if (tx->local->total_ps_buffered >= TOTAL_MAX_TX_BUFFER)
			purge_old_ps_buffers(tx->local);
		if (skb_queue_len(&sta->ps_tx_buf) >= STA_MAX_TX_BUFFER) {
			struct sk_buff *old = skb_dequeue(&sta->ps_tx_buf);
			if (net_ratelimit()) {
				printk(KERN_DEBUG "%s: STA %s TX "
				       "buffer full - dropping oldest frame\n",
				       tx->dev->name, print_mac(mac, sta->addr));
			}
			dev_kfree_skb(old);
		} else
			tx->local->total_ps_buffered++;
		/* Queue frame to be sent after STA sends an PS Poll frame */
		if (skb_queue_empty(&sta->ps_tx_buf)) {
			if (tx->local->ops->set_tim)
				tx->local->ops->set_tim(local_to_hw(tx->local),
						       sta->aid, 1);
			if (tx->sdata->bss)
				bss_tim_set(tx->local, tx->sdata->bss, sta->aid);
		}
		pkt_data = (struct ieee80211_tx_packet_data *)tx->skb->cb;
		pkt_data->jiffies = jiffies;
		skb_queue_tail(&sta->ps_tx_buf, tx->skb);
		return TXRX_QUEUED;
	}
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
	else if (unlikely(sta->flags & WLAN_STA_PS)) {
		printk(KERN_DEBUG "%s: STA %s in PS mode, but pspoll "
		       "set -> send frame\n", tx->dev->name,
		       print_mac(mac, sta->addr));
	}
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
	sta->pspoll = 0;

	return TXRX_CONTINUE;
}


static ieee80211_txrx_result
ieee80211_tx_h_ps_buf(struct ieee80211_txrx_data *tx)
{
	if (unlikely(tx->flags & IEEE80211_TXRXD_TXPS_BUFFERED))
		return TXRX_CONTINUE;

	if (tx->flags & IEEE80211_TXRXD_TXUNICAST)
		return ieee80211_tx_h_unicast_ps_buf(tx);
	else
		return ieee80211_tx_h_multicast_ps_buf(tx);
}




static ieee80211_txrx_result
ieee80211_tx_h_select_key(struct ieee80211_txrx_data *tx)
{
	struct ieee80211_key *key;

	if (unlikely(tx->u.tx.control->flags & IEEE80211_TXCTL_DO_NOT_ENCRYPT))
		tx->key = NULL;
	else if (tx->sta && (key = rcu_dereference(tx->sta->key)))
		tx->key = key;
	else if ((key = rcu_dereference(tx->sdata->default_key)))
		tx->key = key;
	else if (tx->sdata->drop_unencrypted &&
		 !(tx->sdata->eapol && ieee80211_is_eapol(tx->skb))) {
		I802_DEBUG_INC(tx->local->tx_handlers_drop_unencrypted);
		return TXRX_DROP;
	} else {
		tx->key = NULL;
		tx->u.tx.control->flags |= IEEE80211_TXCTL_DO_NOT_ENCRYPT;
	}

	if (tx->key) {
		tx->key->tx_rx_count++;
		/* TODO: add threshold stuff again */
	}

	return TXRX_CONTINUE;
}

static ieee80211_txrx_result
ieee80211_tx_h_fragment(struct ieee80211_txrx_data *tx)
{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) tx->skb->data;
	size_t hdrlen, per_fragm, num_fragm, payload_len, left;
	struct sk_buff **frags, *first, *frag;
	int i;
	u16 seq;
	u8 *pos;
	int frag_threshold = tx->local->fragmentation_threshold;