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

/* src/p80211/p80211conv.c
*
* Ether/802.11 conversions and packet buffer routines
*
* Copyright (C) 1999 AbsoluteValue Systems, Inc.  All Rights Reserved.
* --------------------------------------------------------------------
*
* linux-wlan
*
*   The contents of this file are subject to the Mozilla Public
*   License Version 1.1 (the "License"); you may not use this file
*   except in compliance with the License. You may obtain a copy of
*   the License at http://www.mozilla.org/MPL/
*
*   Software distributed under the License is distributed on an "AS
*   IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
*   implied. See the License for the specific language governing
*   rights and limitations under the License.
*
*   Alternatively, the contents of this file may be used under the
*   terms of the GNU Public License version 2 (the "GPL"), in which
*   case the provisions of the GPL are applicable instead of the
*   above.  If you wish to allow the use of your version of this file
*   only under the terms of the GPL and not to allow others to use
*   your version of this file under the MPL, indicate your decision
*   by deleting the provisions above and replace them with the notice
*   and other provisions required by the GPL.  If you do not delete
*   the provisions above, a recipient may use your version of this
*   file under either the MPL or the GPL.
*
* --------------------------------------------------------------------
*
* Inquiries regarding the linux-wlan Open Source project can be
* made directly to:
*
* AbsoluteValue Systems Inc.
* [e-mail]
* http://www.linux-wlan.com
*
* --------------------------------------------------------------------
*
* Portions of the development of this software were funded by 
* Intersil Corporation as part of PRISM(R) chipset product development.
*
* --------------------------------------------------------------------
*
* This file defines the functions that perform Ethernet to/from
* 802.11 frame conversions.  Additionally,  the functions for
* manipulating the wlan_pb_t packet buffer structures are here.
*
* --------------------------------------------------------------------
*/


/*================================================================*/
/* System Includes */

#define __NO_VERSION__		/* prevent the static definition */

#include <linux/config.h>
#include <linux/version.h>
#include <wlan/wlan_compat.h>

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <asm/byteorder.h>

/*================================================================*/
/* Project Includes */

#include <wlan/version.h>
#include <wlan/p80211types.h>
#include <wlan/p80211hdr.h>
#include <wlan/p80211conv.h>
#include <wlan/p80211mgmt.h>
#include <wlan/p80211msg.h>
#include <wlan/p80211netdev.h>
#include <wlan/p80211ioctl.h>
#include <wlan/p80211req.h>


/*================================================================*/
/* Local Constants */

/*================================================================*/
/* Local Macros */


/*================================================================*/
/* Local Types */


/*================================================================*/
/* Local Static Definitions */

static UINT8	oui_rfc1042[] = {0x00, 0x00, 0x00};
static UINT8	oui_8021h[] = {0x00, 0x00, 0xf8};

/*================================================================*/
/* Local Function Declarations */


/*================================================================*/
/* Function Definitions */

/*----------------------------------------------------------------
* p80211pb_ether_to_80211
*
* Uses the contents of the ether frame and the etherconv setting
* to build the elements of the 802.11 frame.  
*
* We don't actually set 
* up the frame header here.  That's the MAC's job.  We're only handling
* conversion of DIXII or 802.3+LLC frames to something that works
* with 802.11.
*
* Assume the following are already set:
*   pb->ethfree
*   pb->ethhostbuf
*   pb->ethbuf;
*   pb->ethbuflen
*   pb->eth_hdr
*	returns: zero on success, non-zero on failure
*
* Arguments:
*	ethconv		Conversion type to perform
*	pb		Packet buffer containing the ether frame
*
* Returns: 
*	0 on success, non-zero otherwise
*	
* Call context:
*	May be called in interrupt or non-interrupt context
----------------------------------------------------------------*/
int p80211pb_ether_to_p80211( wlandevice_t *wlandev, UINT32 ethconv, wlan_pb_t *pb)
{
	UINT16	proto;
	UINT16	fc;
	UINT8	*a1 = NULL;
	UINT8	*a2 = NULL;
	UINT8	*a3 = NULL;

	DBFENTER;

	if ( ethconv == WLAN_ETHCONV_ENCAP ) { /* simplest case */
		/* here, we don't care what kind of ether frm. Just stick it */
		/*  in the 80211 payload */
		pb->p80211hostbuf = kmalloc( WLAN_HDR_A3_LEN, GFP_ATOMIC);
		if ( pb->p80211hostbuf == NULL ) {
			return 1;
			WLAN_LOG_DEBUG0(1, "Failed to alloc hostbuf1\n");
		}
		pb->p80211buflen = WLAN_HDR_A3_LEN;
		pb->p80211free = p80211pb_kfree_s;
		pb->p80211buf = (UINT8*)(pb->p80211hostbuf);
		pb->p80211_hdr = (p80211_hdr_t*)pb->p80211buf;
		pb->p80211_payload = pb->ethbuf;
		pb->p80211_payloadlen = pb->ethbuflen;
	} else {
		/* step 1: classify ether frame, DIX or 802.3? */
		proto = ntohs(pb->eth_hdr->type);
		if ( proto <= 1500 ) { /* codes <= 1500 reserved for 802.3 lengths */
			/* it's 802.3, pass ether payload unchanged,  */
			/*   leave off any PAD octets.  */
			pb->p80211hostbuf = kmalloc( WLAN_HDR_A3_LEN, GFP_ATOMIC);
			if ( pb->p80211hostbuf == NULL ) {
				WLAN_LOG_DEBUG0(1, "Failed to alloc hostbuf2\n");
				return 1;
			}
			pb->p80211buflen = WLAN_HDR_A3_LEN;
			pb->p80211free = p80211pb_kfree_s;
			pb->p80211buf = (UINT8*)(pb->p80211hostbuf);
			pb->p80211_hdr = (p80211_hdr_t*)pb->p80211buf;

			/* setup the payload ptrs */
			pb->p80211_payload = pb->ethbuf + sizeof(wlan_ethhdr_t);
			pb->p80211_payloadlen = ntohs(pb->eth_hdr->type);
		} else {
			/* it's DIXII, time for some conversion */
			pb->p80211hostbuf = kmalloc( 
						WLAN_HDR_A3_LEN + 
						sizeof(wlan_llc_t) +
						sizeof(wlan_snap_t), GFP_ATOMIC);
			if ( pb->p80211hostbuf == NULL ) {
				WLAN_LOG_DEBUG0(1, "Failed to alloc hostbuf3\n");
				return 1;
			}
			pb->p80211buflen = 
						WLAN_HDR_A3_LEN + 
						sizeof(wlan_llc_t) +
						sizeof(wlan_snap_t);
			pb->p80211free = p80211pb_kfree_s;
			pb->p80211buf = (UINT8*)pb->p80211hostbuf;
			pb->p80211_hdr = (p80211_hdr_t*)pb->p80211buf;
			pb->p80211_llc = (wlan_llc_t*)(pb->p80211buf + WLAN_HDR_A3_LEN);
			pb->p80211_snap = (wlan_snap_t*)(((UINT8*)pb->p80211_llc) + sizeof(wlan_llc_t));

			/* setup the LLC header */
			pb->p80211_llc->dsap = 0xAA;	/* SNAP, see IEEE 802 */
			pb->p80211_llc->ssap = 0xAA;
			pb->p80211_llc->ctl = 0x03;
		
			/* setup the SNAP header */
			pb->p80211_snap->type = htons(proto);
			if ( ethconv == WLAN_ETHCONV_8021h && 
				 p80211_stt_findproto(proto) ) {
				memcpy( pb->p80211_snap->oui, oui_8021h, WLAN_IEEE_OUI_LEN);
			} else {
				memcpy( pb->p80211_snap->oui, oui_rfc1042, WLAN_IEEE_OUI_LEN);
			}

			/* setup the payload ptrs */
			pb->p80211_payload = pb->ethbuf + sizeof(wlan_ethhdr_t);
			pb->p80211_payloadlen = pb->ethbuflen - sizeof(wlan_ethhdr_t);

		}
	}

	/* Set up the 802.11 header */
	/* It's a data frame */
	fc = host2ieee16( WLAN_SET_FC_FTYPE(WLAN_FTYPE_DATA) |  
			WLAN_SET_FC_FSTYPE(WLAN_FSTYPE_DATAONLY));
	pb->p80211_hdr->a3.dur = 0;
	pb->p80211_hdr->a3.seq = 0;

	switch ( wlandev->macmode ) {
	case WLAN_MACMODE_IBSS_STA: 
		a1 = pb->eth_hdr->daddr;	/*dest*/
		a2 = wlandev->netdev->dev_addr;	/*src*/
		a3 = wlandev->bssid;		/*bssid*/
		break;
	case WLAN_MACMODE_ESS_STA:
		fc |= host2ieee16(WLAN_SET_FC_TODS(1));
		a1 = wlandev->bssid;		/*bssid*/
		a2 = wlandev->netdev->dev_addr;	/*src*/
		a3 = pb->eth_hdr->daddr;	/*dest*/
		break;
	case WLAN_MACMODE_ESS_AP:
		fc |= host2ieee16(WLAN_SET_FC_FROMDS(1));
		a1 = pb->eth_hdr->daddr;
		a2 = wlandev->bssid;
		a3 = pb->eth_hdr->saddr;
		break;
	default:
		WLAN_LOG_ERROR0("Error: Converting eth to wlan in unknown mode.\n");
		return 1;
		break;
	}
	pb->p80211_hdr->a3.fc = fc;
	memcpy( pb->p80211_hdr->a3.a1, a1, WLAN_ADDR_LEN); 
	memcpy( pb->p80211_hdr->a3.a2, a2, WLAN_ADDR_LEN);
	memcpy( pb->p80211_hdr->a3.a3, a3, WLAN_ADDR_LEN);

	/* Note that lower layers may set more bits in the fc field */

	DBFEXIT;
	return 0;
}


/*----------------------------------------------------------------
* p80211pb_80211_to_ether
*
* Uses the contents of a received 802.11 frame and the etherconv 
* setting to build an ether frame.
*
* This function extracts the src and dest address from the 802.11
* frame to use in the construction of the eth frame.
*
* This function _will_ set the ethfree member.  If a caller wants
* to allow some other component (a higher layer?) take responsiblity
* for freeing the ethhostbuf, the caller should set ethfree to NULL.
*
* Assume the following are already set:
*	pb->p80211free
*	pb->p80211hostbuf
*	pb->p80211buf
*	pb->p80211buflen
*	pb->p80211_hdr
*	pb->p80211_payload
*	pb->p80211_payloadlen
*
* Arguments:
*	ethconv		Conversion type to perform
*	pb		Packet buffer containing the 802.11 frame
*
* Returns: 
*	0 on success, non-zero otherwise
*	
* Call context:
*	May be called in interrupt or non-interrupt context
----------------------------------------------------------------*/
int p80211pb_p80211_to_ether( wlandevice_t *wlandev, UINT32 ethconv, wlan_pb_t *pb)
{
	UINT8			*daddr = NULL;
	UINT8			*saddr = NULL;
	wlan_ethhdr_t	*ethhdr;
	UINT			llclen;		/* 802 LLC+data length */
	UINT			dixlen;		/* DIX data length */
	UINT			buflen;		/* full frame length, including PAD */
	UINT16			fc;

	/* setup some vars for convenience */
	fc = ieee2host16(pb->p80211_hdr->a3.fc);
	if ( (WLAN_GET_FC_TODS(fc) == 0) && (WLAN_GET_FC_FROMDS(fc) == 0) ) {
		daddr = pb->p80211_hdr->a3.a1;
		saddr = pb->p80211_hdr->a3.a2;
	} else if( (WLAN_GET_FC_TODS(fc) == 0) && (WLAN_GET_FC_FROMDS(fc) == 1) ) {
		daddr = pb->p80211_hdr->a3.a1;
		saddr = pb->p80211_hdr->a3.a3;
	} else if( (WLAN_GET_FC_TODS(fc) == 1) && (WLAN_GET_FC_FROMDS(fc) == 0) ) {
		daddr = pb->p80211_hdr->a3.a3;
		saddr = pb->p80211_hdr->a3.a2;
	} else {
		WLAN_LOG_ERROR0("HDR_A4 detected! A4 currently not supported.\n");
		/* set some bogus pointers so at least we won't crash */
		daddr = pb->p80211_hdr->a3.a1;
		saddr = pb->p80211_hdr->a3.a2;
	}

	ethhdr = (wlan_ethhdr_t*)(pb->p80211_payload);
	pb->p80211_llc = (wlan_llc_t*)(((UINT8*)pb->p80211_hdr) + sizeof(p80211_hdr_a3_t));
	pb->p80211_snap = (wlan_snap_t*)(((UINT8*)pb->p80211_llc) + sizeof(wlan_llc_t));

	/* Test for the various encodings */
	if ( memcmp( daddr, ethhdr->daddr, WLAN_ETHADDR_LEN) == 0 && 
		memcmp(  saddr, ethhdr->saddr, WLAN_ETHADDR_LEN) == 0 ) {
		/* ENCAP */
		/* Test for an overlength frame */
		if ( pb->p80211frmlen > WLAN_HDR_A3_LEN+WLAN_CRC_LEN+WLAN_MAX_ETHFRM_LEN) {
			/* A bogus length ethfrm has been encap'd. */
			/* Is someone trying an oflow attack? */
			return 1;
		}

		/* allocate space and setup host buffer */
		buflen = llclen = pb->p80211frmlen - WLAN_HDR_A3_LEN - WLAN_CRC_LEN;
		pb->ethhostbuf = dev_alloc_skb(buflen + 2); /* +2 is attempt to align IP header */
		if ( pb->ethhostbuf == NULL ) return 1;
		pb->ethfree = p80211pb_freeskb;
		skb_reserve( pb->ethhostbuf, 2);