hostap_80211_tx.c

linux内核源码

#include "hostap_80211.h"
#include "hostap_common.h"
#include "hostap_wlan.h"
#include "hostap.h"
#include "hostap_ap.h"

/* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
/* Ethernet-II snap header (RFC1042 for most EtherTypes) */
static unsigned char rfc1042_header[] =
{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };
/* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
static unsigned char bridge_tunnel_header[] =
{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
/* No encapsulation header if EtherType < 0x600 (=length) */

void hostap_dump_tx_80211(const char *name, struct sk_buff *skb)
{
	struct ieee80211_hdr_4addr *hdr;
	u16 fc;
	DECLARE_MAC_BUF(mac);

	hdr = (struct ieee80211_hdr_4addr *) skb->data;

	printk(KERN_DEBUG "%s: TX len=%d jiffies=%ld\n",
	       name, skb->len, jiffies);

	if (skb->len < 2)
		return;

	fc = le16_to_cpu(hdr->frame_ctl);
	printk(KERN_DEBUG "   FC=0x%04x (type=%d:%d)%s%s",
	       fc, WLAN_FC_GET_TYPE(fc) >> 2, WLAN_FC_GET_STYPE(fc) >> 4,
	       fc & IEEE80211_FCTL_TODS ? " [ToDS]" : "",
	       fc & IEEE80211_FCTL_FROMDS ? " [FromDS]" : "");

	if (skb->len < IEEE80211_DATA_HDR3_LEN) {
		printk("\n");
		return;
	}

	printk(" dur=0x%04x seq=0x%04x\n", le16_to_cpu(hdr->duration_id),
	       le16_to_cpu(hdr->seq_ctl));

	printk(KERN_DEBUG "   A1=%s", print_mac(mac, hdr->addr1));
	printk(" A2=%s", print_mac(mac, hdr->addr2));
	printk(" A3=%s", print_mac(mac, hdr->addr3));
	if (skb->len >= 30)
		printk(" A4=%s", print_mac(mac, hdr->addr4));
	printk("\n");
}


/* hard_start_xmit function for data interfaces (wlan#, wlan#wds#, wlan#sta)
 * Convert Ethernet header into a suitable IEEE 802.11 header depending on
 * device configuration. */
int hostap_data_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct hostap_interface *iface;
	local_info_t *local;
	int need_headroom, need_tailroom = 0;
	struct ieee80211_hdr_4addr hdr;
	u16 fc, ethertype = 0;
	enum {
		WDS_NO = 0, WDS_OWN_FRAME, WDS_COMPLIANT_FRAME
	} use_wds = WDS_NO;
	u8 *encaps_data;
	int hdr_len, encaps_len, skip_header_bytes;
	int to_assoc_ap = 0;
	struct hostap_skb_tx_data *meta;

	iface = netdev_priv(dev);
	local = iface->local;

	if (skb->len < ETH_HLEN) {
		printk(KERN_DEBUG "%s: hostap_data_start_xmit: short skb "
		       "(len=%d)\n", dev->name, skb->len);
		kfree_skb(skb);
		return 0;
	}

	if (local->ddev != dev) {
		use_wds = (local->iw_mode == IW_MODE_MASTER &&
			   !(local->wds_type & HOSTAP_WDS_STANDARD_FRAME)) ?
			WDS_OWN_FRAME : WDS_COMPLIANT_FRAME;
		if (dev == local->stadev) {
			to_assoc_ap = 1;
			use_wds = WDS_NO;
		} else if (dev == local->apdev) {
			printk(KERN_DEBUG "%s: prism2_tx: trying to use "
			       "AP device with Ethernet net dev\n", dev->name);
			kfree_skb(skb);
			return 0;
		}
	} else {
		if (local->iw_mode == IW_MODE_REPEAT) {
			printk(KERN_DEBUG "%s: prism2_tx: trying to use "
			       "non-WDS link in Repeater mode\n", dev->name);
			kfree_skb(skb);
			return 0;
		} else if (local->iw_mode == IW_MODE_INFRA &&
			   (local->wds_type & HOSTAP_WDS_AP_CLIENT) &&
			   memcmp(skb->data + ETH_ALEN, dev->dev_addr,
				  ETH_ALEN) != 0) {
			/* AP client mode: send frames with foreign src addr
			 * using 4-addr WDS frames */
			use_wds = WDS_COMPLIANT_FRAME;
		}
	}

	/* Incoming skb->data: dst_addr[6], src_addr[6], proto[2], payload
	 * ==>
	 * Prism2 TX frame with 802.11 header:
	 * txdesc (address order depending on used mode; includes dst_addr and
	 * src_addr), possible encapsulation (RFC1042/Bridge-Tunnel;
	 * proto[2], payload {, possible addr4[6]} */

	ethertype = (skb->data[12] << 8) | skb->data[13];

	memset(&hdr, 0, sizeof(hdr));

	/* Length of data after IEEE 802.11 header */
	encaps_data = NULL;
	encaps_len = 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;
		encaps_len = sizeof(rfc1042_header);
		skip_header_bytes -= 2;
	}

	fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA;
	hdr_len = IEEE80211_DATA_HDR3_LEN;

	if (use_wds != WDS_NO) {
		/* Note! Prism2 station firmware has problems with sending real
		 * 802.11 frames with four addresses; until these problems can
		 * be fixed or worked around, 4-addr frames needed for WDS are
		 * using incompatible format: FromDS flag is not set and the
		 * fourth address is added after the frame payload; it is
		 * assumed, that the receiving station knows how to handle this
		 * frame format */

		if (use_wds == WDS_COMPLIANT_FRAME) {
			fc |= IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS;
			/* From&To DS: Addr1 = RA, Addr2 = TA, Addr3 = DA,
			 * Addr4 = SA */
			skb_copy_from_linear_data_offset(skb, ETH_ALEN,
							 &hdr.addr4, ETH_ALEN);
			hdr_len += ETH_ALEN;
		} else {
			/* bogus 4-addr format to workaround Prism2 station
			 * f/w bug */
			fc |= IEEE80211_FCTL_TODS;
			/* From DS: Addr1 = DA (used as RA),
			 * Addr2 = BSSID (used as TA), Addr3 = SA (used as DA),
			 */

			/* SA from skb->data + ETH_ALEN will be added after
			 * frame payload; use hdr.addr4 as a temporary buffer
			 */
			skb_copy_from_linear_data_offset(skb, ETH_ALEN,
							 &hdr.addr4, ETH_ALEN);
			need_tailroom += ETH_ALEN;
		}

		/* send broadcast and multicast frames to broadcast RA, if
		 * configured; otherwise, use unicast RA of the WDS link */
		if ((local->wds_type & HOSTAP_WDS_BROADCAST_RA) &&
		    skb->data[0] & 0x01)
			memset(&hdr.addr1, 0xff, ETH_ALEN);
		else if (iface->type == HOSTAP_INTERFACE_WDS)
			memcpy(&hdr.addr1, iface->u.wds.remote_addr,
			       ETH_ALEN);
		else
			memcpy(&hdr.addr1, local->bssid, ETH_ALEN);
		memcpy(&hdr.addr2, dev->dev_addr, ETH_ALEN);
		skb_copy_from_linear_data(skb, &hdr.addr3, ETH_ALEN);
	} else if (local->iw_mode == IW_MODE_MASTER && !to_assoc_ap) {
		fc |= IEEE80211_FCTL_FROMDS;
		/* From DS: Addr1 = DA, Addr2 = BSSID, Addr3 = SA */
		skb_copy_from_linear_data(skb, &hdr.addr1, ETH_ALEN);
		memcpy(&hdr.addr2, dev->dev_addr, ETH_ALEN);
		skb_copy_from_linear_data_offset(skb, ETH_ALEN, &hdr.addr3,
						 ETH_ALEN);
	} else if (local->iw_mode == IW_MODE_INFRA || to_assoc_ap) {
		fc |= IEEE80211_FCTL_TODS;
		/* To DS: Addr1 = BSSID, Addr2 = SA, Addr3 = DA */
		memcpy(&hdr.addr1, to_assoc_ap ?
		       local->assoc_ap_addr : local->bssid, ETH_ALEN);
		skb_copy_from_linear_data_offset(skb, ETH_ALEN, &hdr.addr2,
						 ETH_ALEN);
		skb_copy_from_linear_data(skb, &hdr.addr3, ETH_ALEN);
	} else if (local->iw_mode == IW_MODE_ADHOC) {
		/* not From/To DS: Addr1 = DA, Addr2 = SA, Addr3 = BSSID */
		skb_copy_from_linear_data(skb, &hdr.addr1, ETH_ALEN);
		skb_copy_from_linear_data_offset(skb, ETH_ALEN, &hdr.addr2,
						 ETH_ALEN);
		memcpy(&hdr.addr3, local->bssid, ETH_ALEN);
	}

	hdr.frame_ctl = cpu_to_le16(fc);

	skb_pull(skb, skip_header_bytes);
	need_headroom = local->func->need_tx_headroom + hdr_len + encaps_len;
	if (skb_tailroom(skb) < need_tailroom) {
		skb = skb_unshare(skb, GFP_ATOMIC);
		if (skb == NULL) {
			iface->stats.tx_dropped++;
			return 0;
		}
		if (pskb_expand_head(skb, need_headroom, need_tailroom,
				     GFP_ATOMIC)) {
			kfree_skb(skb);
			iface->stats.tx_dropped++;
			return 0;
		}
	} else if (skb_headroom(skb) < need_headroom) {
		struct sk_buff *tmp = skb;
		skb = skb_realloc_headroom(skb, need_headroom);
		kfree_skb(tmp);
		if (skb == NULL) {
			iface->stats.tx_dropped++;
			return 0;
		}
	} else {
		skb = skb_unshare(skb, GFP_ATOMIC);
		if (skb == NULL) {
			iface->stats.tx_dropped++;
			return 0;
		}
	}

	if (encaps_data)
		memcpy(skb_push(skb, encaps_len), encaps_data, encaps_len);
	memcpy(skb_push(skb, hdr_len), &hdr, hdr_len);
	if (use_wds == WDS_OWN_FRAME) {
		memcpy(skb_put(skb, ETH_ALEN), &hdr.addr4, ETH_ALEN);
	}

	iface->stats.tx_packets++;
	iface->stats.tx_bytes += skb->len;

	skb_reset_mac_header(skb);
	meta = (struct hostap_skb_tx_data *) skb->cb;
	memset(meta, 0, sizeof(*meta));
	meta->magic = HOSTAP_SKB_TX_DATA_MAGIC;
	if (use_wds)
		meta->flags |= HOSTAP_TX_FLAGS_WDS;
	meta->ethertype = ethertype;
	meta->iface = iface;

	/* Send IEEE 802.11 encapsulated frame using the master radio device */
	skb->dev = local->dev;
	dev_queue_xmit(skb);
	return 0;
}


/* hard_start_xmit function for hostapd wlan#ap interfaces */
int hostap_mgmt_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct hostap_interface *iface;
	local_info_t *local;
	struct hostap_skb_tx_data *meta;
	struct ieee80211_hdr_4addr *hdr;
	u16 fc;

	iface = netdev_priv(dev);
	local = iface->local;

	if (skb->len < 10) {