ieee80211_tx.c

Source for the 802.11 (wireless) network stack for Linux

		fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA |
		    IEEE80211_FCTL_PROTECTED;
	else
		fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA;

	if (ieee->iw_mode == IW_MODE_INFRA) {
		fc |= IEEE80211_FCTL_TODS;
		/* To DS: Addr1 = BSSID, Addr2 = SA, Addr3 = DA */
		memcpy(header.addr1, ieee->bssid, ETH_ALEN);
		memcpy(header.addr2, src, ETH_ALEN);
		memcpy(header.addr3, dest, ETH_ALEN);
	} else if (ieee->iw_mode == IW_MODE_ADHOC) {
		/* not From/To DS: Addr1 = DA, Addr2 = SA, Addr3 = BSSID */
		memcpy(header.addr1, dest, ETH_ALEN);
		memcpy(header.addr2, src, ETH_ALEN);
		memcpy(header.addr3, ieee->bssid, ETH_ALEN);
	}
	header.frame_ctl = cpu_to_le16(fc);
	hdr_len = IEEE80211_3ADDR_LEN;

	/* Encrypt msdu first on the whole data packet. */
	if ((host_encrypt || host_encrypt_msdu) &&
	    crypt && crypt->ops && crypt->ops->encrypt_msdu) {
		int res = 0;
		int len = bytes + hdr_len + crypt->ops->extra_msdu_prefix_len +
		    crypt->ops->extra_msdu_postfix_len;
		struct sk_buff *skb_new = dev_alloc_skb(len);

		if (unlikely(!skb_new))
			goto failed;

		skb_reserve(skb_new, crypt->ops->extra_msdu_prefix_len);
		memcpy(skb_put(skb_new, hdr_len), &header, hdr_len);
		snapped = 1;
		ieee80211_copy_snap(skb_put(skb_new, SNAP_SIZE + sizeof(u16)),
				    ether_type);
		memcpy(skb_put(skb_new, skb->len), skb->data, skb->len);
		res = crypt->ops->encrypt_msdu(skb_new, hdr_len, crypt->priv);
		if (res < 0) {
			IEEE80211_ERROR("msdu encryption failed\n");
			dev_kfree_skb_any(skb_new);
			goto failed;
		}
		dev_kfree_skb_any(skb);
		skb = skb_new;
		bytes += crypt->ops->extra_msdu_prefix_len +
		    crypt->ops->extra_msdu_postfix_len;
		skb_pull(skb, hdr_len);
	}

	if (host_encrypt || ieee->host_open_frag) {
		/* Determine fragmentation size based on destination (multicast
		 * and broadcast are not fragmented) */
		if (is_multicast_ether_addr(dest) ||
		    ieee80211_is_broadcast_ether_addr(dest))
			frag_size = MAX_FRAG_THRESHOLD;
		else
			frag_size = ieee->fts;

		/* Determine amount of payload per fragment.  Regardless of if
		 * this stack is providing the full 802.11 header, one will
		 * eventually be affixed to this fragment -- so we must account
		 * for it when determining the amount of payload space. */
		bytes_per_frag = frag_size - IEEE80211_3ADDR_LEN;
		if (ieee->config &
		    (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
			bytes_per_frag -= IEEE80211_FCS_LEN;

		/* Each fragment may need to have room for encryptiong
		 * pre/postfix */
		if (host_encrypt)
			bytes_per_frag -= crypt->ops->extra_mpdu_prefix_len +
			    crypt->ops->extra_mpdu_postfix_len;

		/* Number of fragments is the total
		 * bytes_per_frag / payload_per_fragment */
		nr_frags = bytes / bytes_per_frag;
		bytes_last_frag = bytes % bytes_per_frag;
		if (bytes_last_frag)
			nr_frags++;
		else
			bytes_last_frag = bytes_per_frag;
	} else {
		nr_frags = 1;
		bytes_per_frag = bytes_last_frag = bytes;
		frag_size = bytes + IEEE80211_3ADDR_LEN;
	}

	rts_required = (frag_size > ieee->rts
			&& ieee->config & CFG_IEEE80211_RTS);
	if (rts_required)
		nr_frags++;

	/* When we allocate the TXB we allocate enough space for the reserve
	 * and full fragment bytes (bytes_per_frag doesn't include prefix,
	 * postfix, header, FCS, etc.) */
	txb = ieee80211_alloc_txb(nr_frags, frag_size, GFP_ATOMIC);
	if (unlikely(!txb)) {
		printk(KERN_WARNING "%s: Could not allocate TXB\n",
		       ieee->dev->name);
		goto failed;
	}
	txb->encrypted = encrypt;
	if (host_encrypt)
		txb->payload_size = frag_size * (nr_frags - 1) +
		    bytes_last_frag;
	else
		txb->payload_size = bytes;

	if (rts_required) {
		skb_frag = txb->fragments[0];
		frag_hdr =
		    (struct ieee80211_hdr_3addr *)skb_put(skb_frag, hdr_len);

		/*
		 * Set header frame_ctl to the RTS.
		 */
		header.frame_ctl =
		    cpu_to_le16(IEEE80211_FTYPE_CTL | IEEE80211_STYPE_RTS);
		memcpy(frag_hdr, &header, hdr_len);

		/*
		 * Restore header frame_ctl to the original data setting.
		 */
		header.frame_ctl = cpu_to_le16(fc);

		if (ieee->config &
		    (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
			skb_put(skb_frag, 4);

		txb->rts_included = 1;
		i = 1;
	} else
		i = 0;

	for (; i < nr_frags; i++) {
		skb_frag = txb->fragments[i];

		if (host_encrypt || host_build_iv)
			skb_reserve(skb_frag,
				    crypt->ops->extra_mpdu_prefix_len);

		frag_hdr =
		    (struct ieee80211_hdr_3addr *)skb_put(skb_frag, hdr_len);
		memcpy(frag_hdr, &header, hdr_len);

		/* If this is not the last fragment, then add the MOREFRAGS
		 * bit to the frame control */
		if (i != nr_frags - 1) {
			frag_hdr->frame_ctl =
			    cpu_to_le16(fc | IEEE80211_FCTL_MOREFRAGS);
			bytes = bytes_per_frag;
		} else {
			/* The last fragment takes the remaining length */
			bytes = bytes_last_frag;
		}

		if (i == 0 && !snapped) {
			ieee80211_copy_snap(skb_put
					    (skb_frag, SNAP_SIZE + sizeof(u16)),
					    ether_type);
			bytes -= SNAP_SIZE + sizeof(u16);
		}

		memcpy(skb_put(skb_frag, bytes), skb->data, bytes);

		/* Advance the SKB... */
		skb_pull(skb, bytes);

		/* Encryption routine will move the header forward in order
		 * to insert the IV between the header and the payload */
		if (host_encrypt)
			ieee80211_encrypt_fragment(ieee, skb_frag, hdr_len);
		else if (host_build_iv) {
			struct ieee80211_crypt_data *crypt;

			crypt = ieee->crypt[ieee->tx_keyidx];
			atomic_inc(&crypt->refcnt);
			if (crypt->ops->build_iv)
				crypt->ops->build_iv(skb_frag, hdr_len,
						     crypt->priv);
			atomic_dec(&crypt->refcnt);
		}

		if (ieee->config &
		    (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
			skb_put(skb_frag, 4);
	}

      success:
	spin_unlock_irqrestore(&ieee->lock, flags);

	dev_kfree_skb_any(skb);

	if (txb) {
		int ret = (*ieee->hard_start_xmit) (txb, dev, priority);
		if (ret == 0) {
			stats->tx_packets++;
			stats->tx_bytes += txb->payload_size;
			return 0;
		}

		if (ret == NETDEV_TX_BUSY) {
			printk(KERN_ERR "%s: NETDEV_TX_BUSY returned; "
			       "driver should report queue full via "
			       "ieee_device->is_queue_full.\n",
			       ieee->dev->name);
		}

		ieee80211_txb_free(txb);
	}

	return 0;

      failed:
	spin_unlock_irqrestore(&ieee->lock, flags);
	netif_stop_queue(dev);
	stats->tx_errors++;
	return 1;
}

/* Incoming 802.11 strucure is converted to a TXB
 * a block of 802.11 fragment packets (stored as skbs) */
int ieee80211_tx_frame(struct ieee80211_device *ieee,
		       struct ieee80211_hdr *frame, int len)
{
	struct ieee80211_txb *txb = NULL;
	unsigned long flags;
	struct net_device_stats *stats = &ieee->stats;
	struct sk_buff *skb_frag;
	int priority = -1;

	spin_lock_irqsave(&ieee->lock, flags);

	/* If there is no driver handler to take the TXB, dont' bother
	 * creating it... */
	if (!ieee->hard_start_xmit) {
		printk(KERN_WARNING "%s: No xmit handler.\n", ieee->dev->name);
		goto success;
	}

	if (unlikely(len < 24)) {
		printk(KERN_WARNING "%s: skb too small (%d).\n",
		       ieee->dev->name, len);
		goto success;
	}

	/* When we allocate the TXB we allocate enough space for the reserve
	 * and full fragment bytes (bytes_per_frag doesn't include prefix,
	 * postfix, header, FCS, etc.) */
	txb = ieee80211_alloc_txb(1, len, GFP_ATOMIC);
	if (unlikely(!txb)) {
		printk(KERN_WARNING "%s: Could not allocate TXB\n",
		       ieee->dev->name);
		goto failed;
	}
	txb->encrypted = 0;
	txb->payload_size = len;

	skb_frag = txb->fragments[0];

	memcpy(skb_put(skb_frag, len), frame, len);

	if (ieee->config &
	    (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
		skb_put(skb_frag, 4);

      success:
	spin_unlock_irqrestore(&ieee->lock, flags);

	if (txb) {
		if ((*ieee->hard_start_xmit) (txb, ieee->dev, priority) == 0) {
			stats->tx_packets++;
			stats->tx_bytes += txb->payload_size;
			return 0;
		}
		ieee80211_txb_free(txb);
	}
	return 0;

      failed:
	spin_unlock_irqrestore(&ieee->lock, flags);
	stats->tx_errors++;
	return 1;
}

EXPORT_SYMBOL(ieee80211_tx_frame);
EXPORT_SYMBOL(ieee80211_txb_free);