tx.c

linux 内核源代码

		 * __ieee80211_parse_tx_radiotap has now removed
		 * the radiotap header that was present and pre-filled
		 * 'tx' with tx control information.
		 */
	}

	hdr = (struct ieee80211_hdr *) skb->data;

	tx->sta = sta_info_get(local, hdr->addr1);
	tx->fc = le16_to_cpu(hdr->frame_control);

	if (is_multicast_ether_addr(hdr->addr1)) {
		tx->flags &= ~IEEE80211_TXRXD_TXUNICAST;
		control->flags |= IEEE80211_TXCTL_NO_ACK;
	} else {
		tx->flags |= IEEE80211_TXRXD_TXUNICAST;
		control->flags &= ~IEEE80211_TXCTL_NO_ACK;
	}

	if (tx->flags & IEEE80211_TXRXD_FRAGMENTED) {
		if ((tx->flags & IEEE80211_TXRXD_TXUNICAST) &&
		    skb->len + FCS_LEN > local->fragmentation_threshold &&
		    !local->ops->set_frag_threshold)
			tx->flags |= IEEE80211_TXRXD_FRAGMENTED;
		else
			tx->flags &= ~IEEE80211_TXRXD_FRAGMENTED;
	}

	if (!tx->sta)
		control->flags |= IEEE80211_TXCTL_CLEAR_DST_MASK;
	else if (tx->sta->clear_dst_mask) {
		control->flags |= IEEE80211_TXCTL_CLEAR_DST_MASK;
		tx->sta->clear_dst_mask = 0;
	}

	hdrlen = ieee80211_get_hdrlen(tx->fc);
	if (skb->len > hdrlen + sizeof(rfc1042_header) + 2) {
		u8 *pos = &skb->data[hdrlen + sizeof(rfc1042_header)];
		tx->ethertype = (pos[0] << 8) | pos[1];
	}
	control->flags |= IEEE80211_TXCTL_FIRST_FRAGMENT;

	return res;
}

/* Device in tx->dev has a reference added; use dev_put(tx->dev) when
 * finished with it.
 *
 * NB: @tx is uninitialised when passed in here
 */
static int ieee80211_tx_prepare(struct ieee80211_txrx_data *tx,
				struct sk_buff *skb,
				struct net_device *mdev,
				struct ieee80211_tx_control *control)
{
	struct ieee80211_tx_packet_data *pkt_data;
	struct net_device *dev;

	pkt_data = (struct ieee80211_tx_packet_data *)skb->cb;
	dev = dev_get_by_index(&init_net, pkt_data->ifindex);
	if (unlikely(dev && !is_ieee80211_device(dev, mdev))) {
		dev_put(dev);
		dev = NULL;
	}
	if (unlikely(!dev))
		return -ENODEV;
	/* initialises tx with control */
	__ieee80211_tx_prepare(tx, skb, dev, control);
	return 0;
}

static int __ieee80211_tx(struct ieee80211_local *local, struct sk_buff *skb,
			  struct ieee80211_txrx_data *tx)
{
	struct ieee80211_tx_control *control = tx->u.tx.control;
	int ret, i;

	if (!ieee80211_qdisc_installed(local->mdev) &&
	    __ieee80211_queue_stopped(local, 0)) {
		netif_stop_queue(local->mdev);
		return IEEE80211_TX_AGAIN;
	}
	if (skb) {
		ieee80211_dump_frame(wiphy_name(local->hw.wiphy),
				     "TX to low-level driver", skb);
		ret = local->ops->tx(local_to_hw(local), skb, control);
		if (ret)
			return IEEE80211_TX_AGAIN;
		local->mdev->trans_start = jiffies;
		ieee80211_led_tx(local, 1);
	}
	if (tx->u.tx.extra_frag) {
		control->flags &= ~(IEEE80211_TXCTL_USE_RTS_CTS |
				    IEEE80211_TXCTL_USE_CTS_PROTECT |
				    IEEE80211_TXCTL_CLEAR_DST_MASK |
				    IEEE80211_TXCTL_FIRST_FRAGMENT);
		for (i = 0; i < tx->u.tx.num_extra_frag; i++) {
			if (!tx->u.tx.extra_frag[i])
				continue;
			if (__ieee80211_queue_stopped(local, control->queue))
				return IEEE80211_TX_FRAG_AGAIN;
			if (i == tx->u.tx.num_extra_frag) {
				control->tx_rate = tx->u.tx.last_frag_hwrate;
				control->rate = tx->u.tx.last_frag_rate;
				if (tx->flags & IEEE80211_TXRXD_TXPROBE_LAST_FRAG)
					control->flags |=
						IEEE80211_TXCTL_RATE_CTRL_PROBE;
				else
					control->flags &=
						~IEEE80211_TXCTL_RATE_CTRL_PROBE;
			}

			ieee80211_dump_frame(wiphy_name(local->hw.wiphy),
					     "TX to low-level driver",
					     tx->u.tx.extra_frag[i]);
			ret = local->ops->tx(local_to_hw(local),
					    tx->u.tx.extra_frag[i],
					    control);
			if (ret)
				return IEEE80211_TX_FRAG_AGAIN;
			local->mdev->trans_start = jiffies;
			ieee80211_led_tx(local, 1);
			tx->u.tx.extra_frag[i] = NULL;
		}
		kfree(tx->u.tx.extra_frag);
		tx->u.tx.extra_frag = NULL;
	}
	return IEEE80211_TX_OK;
}

static int ieee80211_tx(struct net_device *dev, struct sk_buff *skb,
			struct ieee80211_tx_control *control)
{
	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
	struct sta_info *sta;
	ieee80211_tx_handler *handler;
	struct ieee80211_txrx_data tx;
	ieee80211_txrx_result res = TXRX_DROP, res_prepare;
	int ret, i;

	WARN_ON(__ieee80211_queue_pending(local, control->queue));

	if (unlikely(skb->len < 10)) {
		dev_kfree_skb(skb);
		return 0;
	}

	/* initialises tx */
	res_prepare = __ieee80211_tx_prepare(&tx, skb, dev, control);

	if (res_prepare == TXRX_DROP) {
		dev_kfree_skb(skb);
		return 0;
	}

	/*
	 * key references are protected using RCU and this requires that
	 * we are in a read-site RCU section during receive processing
	 */
	rcu_read_lock();

	sta = tx.sta;
	tx.u.tx.mode = local->hw.conf.mode;

	for (handler = local->tx_handlers; *handler != NULL;
	     handler++) {
		res = (*handler)(&tx);
		if (res != TXRX_CONTINUE)
			break;
	}

	skb = tx.skb; /* handlers are allowed to change skb */

	if (sta)
		sta_info_put(sta);

	if (unlikely(res == TXRX_DROP)) {
		I802_DEBUG_INC(local->tx_handlers_drop);
		goto drop;
	}

	if (unlikely(res == TXRX_QUEUED)) {
		I802_DEBUG_INC(local->tx_handlers_queued);
		rcu_read_unlock();
		return 0;
	}

	if (tx.u.tx.extra_frag) {
		for (i = 0; i < tx.u.tx.num_extra_frag; i++) {
			int next_len, dur;
			struct ieee80211_hdr *hdr =
				(struct ieee80211_hdr *)
				tx.u.tx.extra_frag[i]->data;

			if (i + 1 < tx.u.tx.num_extra_frag) {
				next_len = tx.u.tx.extra_frag[i + 1]->len;
			} else {
				next_len = 0;
				tx.u.tx.rate = tx.u.tx.last_frag_rate;
				tx.u.tx.last_frag_hwrate = tx.u.tx.rate->val;
			}
			dur = ieee80211_duration(&tx, 0, next_len);
			hdr->duration_id = cpu_to_le16(dur);
		}
	}

retry:
	ret = __ieee80211_tx(local, skb, &tx);
	if (ret) {
		struct ieee80211_tx_stored_packet *store =
			&local->pending_packet[control->queue];

		if (ret == IEEE80211_TX_FRAG_AGAIN)
			skb = NULL;
		set_bit(IEEE80211_LINK_STATE_PENDING,
			&local->state[control->queue]);
		smp_mb();
		/* When the driver gets out of buffers during sending of
		 * fragments and calls ieee80211_stop_queue, there is
		 * a small window between IEEE80211_LINK_STATE_XOFF and
		 * IEEE80211_LINK_STATE_PENDING flags are set. If a buffer
		 * gets available in that window (i.e. driver calls
		 * ieee80211_wake_queue), we would end up with ieee80211_tx
		 * called with IEEE80211_LINK_STATE_PENDING. Prevent this by
		 * continuing transmitting here when that situation is
		 * possible to have happened. */
		if (!__ieee80211_queue_stopped(local, control->queue)) {
			clear_bit(IEEE80211_LINK_STATE_PENDING,
				  &local->state[control->queue]);
			goto retry;
		}
		memcpy(&store->control, control,
		       sizeof(struct ieee80211_tx_control));
		store->skb = skb;
		store->extra_frag = tx.u.tx.extra_frag;
		store->num_extra_frag = tx.u.tx.num_extra_frag;
		store->last_frag_hwrate = tx.u.tx.last_frag_hwrate;
		store->last_frag_rate = tx.u.tx.last_frag_rate;
		store->last_frag_rate_ctrl_probe =
			!!(tx.flags & IEEE80211_TXRXD_TXPROBE_LAST_FRAG);
	}
	rcu_read_unlock();
	return 0;

 drop:
	if (skb)
		dev_kfree_skb(skb);
	for (i = 0; i < tx.u.tx.num_extra_frag; i++)
		if (tx.u.tx.extra_frag[i])
			dev_kfree_skb(tx.u.tx.extra_frag[i]);
	kfree(tx.u.tx.extra_frag);
	rcu_read_unlock();
	return 0;
}

/* device xmit handlers */

int ieee80211_master_start_xmit(struct sk_buff *skb,
				struct net_device *dev)
{
	struct ieee80211_tx_control control;
	struct ieee80211_tx_packet_data *pkt_data;
	struct net_device *odev = NULL;
	struct ieee80211_sub_if_data *osdata;
	int headroom;
	int ret;

	/*
	 * copy control out of the skb so other people can use skb->cb
	 */
	pkt_data = (struct ieee80211_tx_packet_data *)skb->cb;
	memset(&control, 0, sizeof(struct ieee80211_tx_control));

	if (pkt_data->ifindex)
		odev = dev_get_by_index(&init_net, pkt_data->ifindex);
	if (unlikely(odev && !is_ieee80211_device(odev, dev))) {
		dev_put(odev);
		odev = NULL;
	}
	if (unlikely(!odev)) {
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
		printk(KERN_DEBUG "%s: Discarded packet with nonexistent "
		       "originating device\n", dev->name);
#endif
		dev_kfree_skb(skb);
		return 0;
	}
	osdata = IEEE80211_DEV_TO_SUB_IF(odev);

	headroom = osdata->local->tx_headroom + IEEE80211_ENCRYPT_HEADROOM;
	if (skb_headroom(skb) < headroom) {
		if (pskb_expand_head(skb, headroom, 0, GFP_ATOMIC)) {
			dev_kfree_skb(skb);
			dev_put(odev);
			return 0;
		}
	}

	control.ifindex = odev->ifindex;
	control.type = osdata->type;
	if (pkt_data->flags & IEEE80211_TXPD_REQ_TX_STATUS)
		control.flags |= IEEE80211_TXCTL_REQ_TX_STATUS;
	if (pkt_data->flags & IEEE80211_TXPD_DO_NOT_ENCRYPT)
		control.flags |= IEEE80211_TXCTL_DO_NOT_ENCRYPT;
	if (pkt_data->flags & IEEE80211_TXPD_REQUEUE)
		control.flags |= IEEE80211_TXCTL_REQUEUE;
	control.queue = pkt_data->queue;

	ret = ieee80211_tx(odev, skb, &control);
	dev_put(odev);

	return ret;
}

int ieee80211_monitor_start_xmit(struct sk_buff *skb,
				 struct net_device *dev)
{
	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
	struct ieee80211_tx_packet_data *pkt_data;
	struct ieee80211_radiotap_header *prthdr =
		(struct ieee80211_radiotap_header *)skb->data;
	u16 len_rthdr;

	/* check for not even having the fixed radiotap header part */
	if (unlikely(skb->len < sizeof(struct ieee80211_radiotap_header)))
		goto fail; /* too short to be possibly valid */

	/* is it a header version we can trust to find length from? */
	if (unlikely(prthdr->it_version))
		goto fail; /* only version 0 is supported */

	/* then there must be a radiotap header with a length we can use */
	len_rthdr = ieee80211_get_radiotap_len(skb->data);

	/* does the skb contain enough to deliver on the alleged length? */
	if (unlikely(skb->len < len_rthdr))
		goto fail; /* skb too short for claimed rt header extent */

	skb->dev = local->mdev;

	pkt_data = (struct ieee80211_tx_packet_data *)skb->cb;
	memset(pkt_data, 0, sizeof(*pkt_data));
	/* needed because we set skb device to master */
	pkt_data->ifindex = dev->ifindex;

	pkt_data->flags |= IEEE80211_TXPD_DO_NOT_ENCRYPT;

	/*
	 * fix up the pointers accounting for the radiotap
	 * header still being in there.  We are being given
	 * a precooked IEEE80211 header so no need for
	 * normal processing
	 */
	skb_set_mac_header(skb, len_rthdr);
	/*
	 * these are just fixed to the end of the rt area since we
	 * don't have any better information and at this point, nobody cares
	 */
	skb_set_network_header(skb, len_rthdr);
	skb_set_transport_header(skb, len_rthdr);

	/* pass the radiotap header up to the next stage intact */
	dev_queue_xmit(skb);
	return NETDEV_TX_OK;

fail:
	dev_kfree_skb(skb);
	return NETDEV_TX_OK; /* meaning, we dealt with the skb */
}

/**
 * ieee80211_subif_start_xmit - netif start_xmit function for Ethernet-type
 * subinterfaces (wlan#, WDS, and VLAN interfaces)
 * @skb: packet to be sent
 * @dev: incoming interface
 *
 * Returns: 0 on success (and frees skb in this case) or 1 on failure (skb will
 * not be freed, and caller is responsible for either retrying later or freeing
 * skb).
 *
 * This function takes in an Ethernet header and encapsulates it with suitable
 * IEEE 802.11 header based on which interface the packet is coming in. The
 * encapsulated packet will then be passed to master interface, wlan#.11, for
 * transmission (through low-level driver).
 */
int ieee80211_subif_start_xmit(struct sk_buff *skb,
			       struct net_device *dev)
{
	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
	struct ieee80211_tx_packet_data *pkt_data;
	struct ieee80211_sub_if_data *sdata;
	int ret = 1, head_need;
	u16 ethertype, hdrlen, fc;
	struct ieee80211_hdr hdr;
	const u8 *encaps_data;
	int encaps_len, skip_header_bytes;
	int nh_pos, h_pos;
	struct sta_info *sta;

	sdata = IEEE80211_DEV_TO_SUB_IF(dev);
	if (unlikely(skb->len < ETH_HLEN)) {
		printk(KERN_DEBUG "%s: short skb (len=%d)\n",
		       dev->name, skb->len);
		ret = 0;
		goto fail;
	}

	nh_pos = skb_network_header(skb) - skb->data;
	h_pos = skb_transport_header(skb) - skb->data;

	/* convert Ethernet header to proper 802.11 header (based on
	 * operation mode) */
	ethertype = (skb->data[12] << 8) | skb->data[13];
	/* TODO: handling for 802.1x authorized/unauthorized port */
	fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA;

	switch (sdata->type) {
	case IEEE80211_IF_TYPE_AP:
	case IEEE80211_IF_TYPE_VLAN:
		fc |= IEEE80211_FCTL_FROMDS;
		/* DA BSSID SA */
		memcpy(hdr.addr1, skb->data, ETH_ALEN);
		memcpy(hdr.addr2, dev->dev_addr, ETH_ALEN);
		memcpy(hdr.addr3, skb->data + ETH_ALEN, ETH_ALEN);
		hdrlen = 24;
		break;
	case IEEE80211_IF_TYPE_WDS:
		fc |= IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS;
		/* RA TA DA SA */
		memcpy(hdr.addr1, sdata->u.wds.remote_addr, ETH_ALEN);
		memcpy(hdr.addr2, dev->dev_addr, ETH_ALEN);
		memcpy(hdr.addr3, skb->data, ETH_ALEN);
		memcpy(hdr.addr4, skb->data + ETH_ALEN, ETH_ALEN);
		hdrlen = 30;
		break;
	case IEEE80211_IF_TYPE_STA:
		fc |= IEEE80211_FCTL_TODS;
		/* BSSID SA DA */
		memcpy(hdr.addr1, sdata->u.sta.bssid, ETH_ALEN);
		memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
		memcpy(hdr.addr3, skb->data, ETH_ALEN);
		hdrlen = 24;
		break;
	case IEEE80211_IF_TYPE_IBSS:
		/* DA SA BSSID */
		memcpy(hdr.addr1, skb->data, ETH_ALEN);
		memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
		memcpy(hdr.addr3, sdata->u.sta.bssid, ETH_ALEN);
		hdrlen = 24;
		break;
	default:
		ret = 0;
		goto fail;
	}

	/* receiver is QoS enabled, use a QoS type frame */
	sta = sta_info_get(local, hdr.addr1);
	if (sta) {
		if (sta->flags & WLAN_STA_WME) {
			fc |= IEEE80211_STYPE_QOS_DATA;
			hdrlen += 2;
		}
		sta_info_put(sta);
	}

	hdr.frame_control = cpu_to_le16(fc);
	hdr.duration_id = 0;
	hdr.seq_ctrl = 0;

	skip_header_bytes = ETH_HLEN;
	if (ethertype == ETH_P_AARP || ethertype == ETH_P_IPX) {
		encaps_data = bridge_tunnel_header;
		encaps_len = sizeof(bridge_tunnel_header);
		skip_header_bytes -= 2;
	} else if (ethertype >= 0x600) {
		encaps_data = rfc1042_header;