p80211conv.c

Linux的无线局域网方案是一个Linux设备驱动程序和子系统 一揽子方案的用意是提供全系列的IEEE 802.11标准的Mac 管理功能

		skb_put( ((struct sk_buff*)pb->ethhostbuf), buflen);	/* make room */
		pb->ethbuf = ((struct sk_buff*)pb->ethhostbuf)->data;
		pb->ethbuflen = buflen;

		/* setup the pointers */
		pb->eth_hdr = (wlan_ethhdr_t*)pb->ethbuf;
		pb->eth_llc = (wlan_llc_t*)(pb->ethbuf + sizeof(wlan_ethhdr_t));
		pb->eth_snap = (wlan_snap_t*)
			(pb->ethbuf + sizeof(wlan_ethhdr_t) + sizeof(wlan_llc_t));
		pb->eth_payload = pb->ethbuf + sizeof(wlan_ethhdr_t);
		pb->eth_payloadlen = buflen - sizeof(wlan_ethhdr_t);

		/* now copy the data from the 80211 frame */
		memcpy( pb->ethbuf, pb->p80211_payload, buflen);	/* copy the data */
	} else if (	pb->p80211_llc->dsap == 0xaa &&
				pb->p80211_llc->ssap == 0xaa &&
				pb->p80211_llc->ctl == 0x03 &&
				memcmp( pb->p80211_snap->oui, 
					oui_rfc1042, WLAN_IEEE_OUI_LEN) == 0 &&
				ethconv == WLAN_ETHCONV_8021h && 
				p80211_stt_findproto(ieee2host16(pb->p80211_snap->type)) ) {
		/* it's a SNAP + RFC1042 frame && protocol is in STT */
		/* build 802.3 + RFC1042 */
		
		/* Test for an overlength frame */
		if ( pb->p80211_payloadlen > WLAN_MAX_ETHFRM_LEN - WLAN_ETHHDR_LEN ) {
			/* A bogus length ethfrm has been sent. */
			/* Is someone trying an oflow attack? */
			return 1;
		}

		llclen = pb->p80211_payloadlen;
		buflen = wlan_max( llclen + sizeof(wlan_ethhdr_t), WLAN_MIN_ETHFRM_LEN);
		pb->ethhostbuf = dev_alloc_skb(buflen + 2); /* +2 is attempt to align IP header */
		if ( pb->ethhostbuf == NULL ) return 1;
		skb_reserve( (struct sk_buff*)pb->ethhostbuf, 2);		
		skb_put( (struct sk_buff*)pb->ethhostbuf, buflen);	/* make room */
		pb->ethbuf = ((struct sk_buff*)pb->ethhostbuf)->data;
		pb->ethbuflen = buflen;
/*		memset( pb->ethbuf, 0, buflen);	*/		/* zero for possible PAD */

		/* set up the pointers */
		pb->eth_hdr = (wlan_ethhdr_t*)pb->ethbuf;
		pb->eth_llc = (wlan_llc_t*)(pb->ethbuf + sizeof(wlan_ethhdr_t));
		pb->eth_snap = (wlan_snap_t*)
			(pb->ethbuf + sizeof(wlan_ethhdr_t) + sizeof(wlan_llc_t));
		pb->eth_payload = pb->ethbuf + sizeof(wlan_ethhdr_t);
		pb->eth_payloadlen = llclen;

		/* set up the 802.3 header */	
		pb->eth_hdr->type = htons(pb->eth_payloadlen);
		memcpy( pb->eth_hdr->daddr, daddr, WLAN_ETHADDR_LEN);
		memcpy( pb->eth_hdr->saddr, saddr, WLAN_ETHADDR_LEN);

		/* now copy the data from the 80211 frame */
		memcpy( pb->eth_payload, pb->p80211_payload, pb->p80211_payloadlen);
	} else if ( pb->p80211_llc->dsap == 0xaa &&
			pb->p80211_llc->ssap == 0xaa &&
			pb->p80211_llc->ctl == 0x03 ) {
		/* it's an 802.1h frame || (an RFC1042 && protocol is not in STT) */
		/* build a DIXII + RFC894 */

		dixlen = pb->p80211_payloadlen - sizeof(wlan_llc_t) - sizeof(wlan_snap_t);

		/* Test for an overlength frame */
		if ( dixlen + WLAN_ETHHDR_LEN > WLAN_MAX_ETHFRM_LEN) {
			/* A bogus length ethfrm has been sent. */
			/* Is someone trying an oflow attack? */
			return 1;
		}

		dixlen = pb->p80211_payloadlen - sizeof(wlan_llc_t) - sizeof(wlan_snap_t);
		buflen = wlan_max( dixlen + sizeof(wlan_ethhdr_t), WLAN_MIN_ETHFRM_LEN);
		pb->ethhostbuf = dev_alloc_skb(buflen + 2); /* +2 is attempt to align IP header */
		if ( pb->ethhostbuf == NULL ) return 1;
		skb_reserve( (struct sk_buff*)pb->ethhostbuf, 2);		
		skb_put( (struct sk_buff*)pb->ethhostbuf, buflen);	/* make room */
		pb->ethbuf = ((struct sk_buff*)pb->ethhostbuf)->data;
		pb->ethbuflen = buflen;
/*		memset( pb->ethbuf, 0, buflen);	*/		/* zero for possible PAD */

		/* set up the pointers */
		pb->eth_hdr = (wlan_ethhdr_t*)pb->ethbuf;
		pb->eth_llc = NULL;
		pb->eth_snap = NULL;
		pb->eth_payload = pb->ethbuf + sizeof(wlan_ethhdr_t);
		pb->eth_payloadlen = dixlen;

		/* make sure the llc and snap ptrs are set */
		pb->p80211_llc = (wlan_llc_t*)pb->p80211_payload;
		pb->p80211_snap = (wlan_snap_t*)
			(pb->p80211_payload + sizeof(wlan_llc_t));

		/* set up the DIXII header */	
		pb->eth_hdr->type = pb->p80211_snap->type;
		memcpy( pb->eth_hdr->daddr, daddr, WLAN_ETHADDR_LEN);
		memcpy( pb->eth_hdr->saddr, saddr, WLAN_ETHADDR_LEN);

		/* now copy the data from the 80211 frame */
		memcpy( pb->eth_payload, 
				pb->p80211_payload + sizeof(wlan_llc_t) + sizeof(wlan_snap_t), 
				dixlen);
	} else {
		/* any NON-ENCAP */
		/* it's a generic 80211+LLC or IPX 'Raw 802.3' */
		/*  build an 802.3 frame */
		/* allocate space and setup hostbuf */

		/* Test for an overlength frame */
		if ( pb->p80211_payloadlen + WLAN_ETHHDR_LEN > WLAN_MAX_ETHFRM_LEN) {
			/* A bogus length ethfrm has been sent. */
			/* Is someone trying an oflow attack? */
			return 1;
		}

		llclen = pb->p80211_payloadlen;
		buflen = wlan_max( llclen + sizeof(wlan_ethhdr_t), WLAN_MIN_ETHFRM_LEN);
		pb->ethhostbuf = dev_alloc_skb(buflen + 2); /* +2 is attempt to align IP header */
		if ( pb->ethhostbuf == NULL ) return 1;
		skb_reserve( (struct sk_buff*)pb->ethhostbuf, 2);		
		skb_put( (struct sk_buff*)pb->ethhostbuf, buflen);	/* make room */
		pb->ethbuf = ((struct sk_buff*)pb->ethhostbuf)->data;
		pb->ethbuflen = buflen;
/*		memset( pb->ethbuf, 0, buflen);	*/		/* zero for possible PAD */

		/* set up the pointers */
		pb->eth_hdr = (wlan_ethhdr_t*)pb->ethbuf;
		pb->eth_llc = (wlan_llc_t*)(pb->ethbuf + sizeof(wlan_ethhdr_t));
		pb->eth_snap = (wlan_snap_t*)
			(pb->ethbuf + sizeof(wlan_ethhdr_t) + sizeof(wlan_llc_t));
		pb->eth_payload = pb->ethbuf + sizeof(wlan_ethhdr_t);
		pb->eth_payloadlen = llclen;

		/* set up the 802.3 header */	
		pb->eth_hdr->type = htons(pb->eth_payloadlen);
		memcpy( pb->eth_hdr->daddr, daddr, WLAN_ETHADDR_LEN);
		memcpy( pb->eth_hdr->saddr, saddr, WLAN_ETHADDR_LEN);

		/* now copy the data from the 80211 frame */
		memcpy( pb->eth_payload, pb->p80211_payload, pb->p80211_payloadlen);
	}
	return 0;
}


/*----------------------------------------------------------------
* p80211pb_freeskb
*
* Free method for wlan_pb's that have skbs in them.  Called
* via ptr from p80211pb_free.  
*
* Arguments:
*	buf	Ptr to an skb
*	size	Passed in to match the ptr declaration.
*		Unused in this function.
*
* Returns: 
*	nothing
*	
* Call context:
*	May be called in interrupt or non-interrupt context
----------------------------------------------------------------*/
void p80211pb_freeskb( void *buf, int size )
{
	dev_kfree_skb( (struct sk_buff*)buf );
}


/*----------------------------------------------------------------
* p80211pb_pbfreeskb
*
* Free method for wlan_pb's that linux kmalloc'd buffers in them.  
* Called via ptr from p80211pb_free.  
*
* Arguments:
*	buf	Ptr to buffer
*	size	Size of buffer
*
* Returns: 
*	nothing
*	
* Call context:
*	May be called in interrupt or non-interrupt context
----------------------------------------------------------------*/
void p80211pb_kfree_s( void *buf, int size)
{
	kfree_s( buf, size);
}


/*----------------------------------------------------------------
* p80211pb_alloc
*
* Allocs and zeros a wlan_pb structure.  Largely here for symmetry
* with the pbfree routine.  Also handy w/ ports to platforms where
* we have fixed alloc pools.
*
* Arguments:
*	none
*
* Returns: 
*	The address of a zeroed wlan_pb on success, NULL otherwise.
*	
* Call context:
*	May be called in interrupt or non-interrupt context
----------------------------------------------------------------*/
wlan_pb_t* p80211pb_alloc(void)
{
	wlan_pb_t	*pb;
	pb = kmalloc( sizeof(wlan_pb_t), GFP_ATOMIC);
	if ( pb != NULL ) {
		memset(pb, 0, sizeof(wlan_pb_t));
	}
	return pb;
}


/*----------------------------------------------------------------
* p80211pb_alloc_p80211
*
* Allocates a buffer for an 80211 frame and sets the ptrs in a 
* given pb.  Primarily used by the receive path.  Handled
* here so that the allocation used and the free method are set
* in one place (helps with portability?).
*
* Arguments:
*	pb	ptr to a wlan_pb_t previously allocated w/ p80211pb_alloc
*		if NULL, calls p80211pb_alloc.
*	size	length of the 802.11 buffer to allocate.  Note that
*		on some platforms w/ fixed size buffer pools, the size
*		will be ignored for allocation but _will_ be set in
*		the pb structure.
*
* Returns: 
*	The address of the given or allocated wlan_pb on success, 
*	NULL otherwise.
*	
* Call context:
*	May be called in interrupt or non-interrupt context
----------------------------------------------------------------*/
wlan_pb_t* p80211pb_alloc_p80211(wlan_pb_t *pb, UINT len)
{
	if ( pb == NULL ) {
		pb = p80211pb_alloc();
	}
	if ( pb != NULL ) {
		pb->p80211hostbuf = kmalloc( len, GFP_ATOMIC);
		if ( pb->p80211hostbuf != NULL ) {
			pb->p80211free = p80211pb_kfree_s;
			pb->p80211buf = (UINT8*)pb->p80211hostbuf;
			pb->p80211buflen = len;
			pb->p80211frmlen = len;		/* initially assume frm is same as buf */
			pb->p80211_hdr = (p80211_hdr_t*)pb->p80211buf;
			pb->p80211_payload = pb->p80211buf + WLAN_HDR_A3_LEN;
			pb->p80211_payloadlen = pb->p80211buflen - WLAN_HDR_A3_LEN - WLAN_CRC_LEN;
		}
	}
	return pb;
}


/*----------------------------------------------------------------
* p80211pb_free
*
* Frees the ethhostbuf and the p80211hostbuf elements of a wlan_pb
* if there is a free method for each.  Then frees the wlan_pb itself.
*
* Arguments:
*	pb	ptr to a wlan_pb_t previously allocated w/ p80211pb_alloc
*		or p80211pb_alloc_p80211.
*
* Returns: 
*	nothing
*	
* Call context:
*	May be called in interrupt or non-interrupt context
----------------------------------------------------------------*/
void p80211pb_free(wlan_pb_t* pb)
{
	if ( pb != NULL ) {
		if ( pb->ethhostbuf != NULL && pb->ethfree != NULL)
		{
			(*(pb->ethfree))(pb->ethhostbuf, pb->ethbuflen);
		}
		if ( pb->p80211hostbuf != NULL && pb->p80211free != NULL)
		{
			(*(pb->p80211free))(pb->p80211hostbuf, pb->p80211buflen);
		}
		kfree_s(pb, sizeof(wlan_pb_t));
	}
}


/*----------------------------------------------------------------
* p80211_stt_findproto
*
* Searches the 802.1h Selective Translation Table for a given 
* protocol.
*
* Arguments:
*	proto	protocl number (in host order) to search for.
*
* Returns: 
*	1 - if the table is empty or a match is found.
*	0 - if the table is non-empty and a match is not found.
*	
* Call context:
*	May be called in interrupt or non-interrupt context
----------------------------------------------------------------*/
int p80211_stt_findproto(UINT16 proto)
{
	/* Always return found for now.  This is the behavior used by the */
	/*  Zoom Win95 driver when 802.1h mode is selected */
	/* TODO: If necessary, add an actual search we'll probably
		 need this to match the CMAC's way of doing things.
		 Need to do some testing to confirm.
	*/

	return 1;
}


#if 0
/* MSM: This function is currently unused.  Not sure if we'll ever need it. */
/*----------------------------------------------------------------
* p80211_stt_addproto
*
* Add a protocol to the 802.1h Selective Translation Table.
*
* Arguments:
*	proto	protocl number (in host order) to search for.
*
* Returns: 
*	nothing
*	
* Call context:
*	May be called in interrupt or non-interrupt context
----------------------------------------------------------------*/
int p80211_stt_addproto(UINT16 proto)
{
	return;
}

#endif