[net-next-2.6.git] / drivers / isdn / i4l / isdn_x25iface.c

/* $Id: isdn_x25iface.c,v 1.1.2.2 2004/01/12 22:37:19 keil Exp $
 *
 * Linux ISDN subsystem, X.25 related functions
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 * stuff needed to support the Linux X.25 PLP code on top of devices that
 * can provide a lab_b service using the concap_proto mechanism.
 * This module supports a network interface which provides lapb_sematics
 * -- as defined in Documentation/networking/x25-iface.txt -- to
 * the upper layer and assumes that the lower layer provides a reliable
 * data link service by means of the concap_device_ops callbacks.
 *
 * Only protocol specific stuff goes here. Device specific stuff
 * goes to another -- device related -- concap_proto support source file.
 *
 */

/* #include <linux/isdn.h> */
#include <linux/netdevice.h>
#include <linux/concap.h>
#include <linux/wanrouter.h>
#include <net/x25device.h>
#include "isdn_x25iface.h"

/* for debugging messages not to cause an oops when device pointer is NULL*/
#define MY_DEVNAME(dev)  ( (dev) ? (dev)->name : "DEVICE UNSPECIFIED" )


typedef struct isdn_x25iface_proto_data {
	int magic;
	enum wan_states state;
	/* Private stuff, not to be accessed via proto_data. We provide the
	   other storage for the concap_proto instance here as well,
	   enabling us to allocate both with just one kmalloc(): */ 
	struct concap_proto priv;
} ix25_pdata_t;


/* is now in header file (extern): struct concap_proto * isdn_x25iface_proto_new(void); */
static void isdn_x25iface_proto_del( struct concap_proto * );
static int isdn_x25iface_proto_close( struct concap_proto * );
static int isdn_x25iface_proto_restart( struct concap_proto *,
					struct net_device *,
					struct concap_device_ops *);
static int isdn_x25iface_xmit( struct concap_proto *, struct sk_buff * );
static int isdn_x25iface_receive( struct concap_proto *, struct sk_buff * );
static int isdn_x25iface_connect_ind( struct concap_proto * );
static int isdn_x25iface_disconn_ind( struct concap_proto * );


static struct concap_proto_ops ix25_pops = {
	&isdn_x25iface_proto_new,
	&isdn_x25iface_proto_del,
	&isdn_x25iface_proto_restart,
	&isdn_x25iface_proto_close,
	&isdn_x25iface_xmit,
	&isdn_x25iface_receive,
	&isdn_x25iface_connect_ind,
	&isdn_x25iface_disconn_ind
};

/* error message helper function */
static void illegal_state_warn( unsigned state, unsigned char firstbyte) 
{
	printk( KERN_WARNING "isdn_x25iface: firstbyte %x illegal in"
		"current state %d\n",firstbyte, state );
}

/* check protocol data field for consistency */
static int pdata_is_bad( ix25_pdata_t * pda ){

	if( pda  &&  pda -> magic == ISDN_X25IFACE_MAGIC ) return 0;
	printk( KERN_WARNING
		"isdn_x25iface_xxx: illegal pointer to proto data\n" );
	return 1;
}

/* create a new x25 interface protocol instance
 */
struct concap_proto * isdn_x25iface_proto_new(void)
{
	ix25_pdata_t * tmp = kmalloc(sizeof(ix25_pdata_t),GFP_KERNEL);
	IX25DEBUG("isdn_x25iface_proto_new\n");
	if( tmp ){
		tmp -> magic = ISDN_X25IFACE_MAGIC;
		tmp -> state = WAN_UNCONFIGURED;
		/* private data space used to hold the concap_proto data.
		   Only to be accessed via the returned pointer */
		spin_lock_init(&tmp->priv.lock);
		tmp -> priv.dops       = NULL;
		tmp -> priv.net_dev    = NULL;
		tmp -> priv.pops       = &ix25_pops;
		tmp -> priv.flags      = 0;
		tmp -> priv.proto_data = tmp;
		return( &(tmp -> priv) );
	}
	return NULL;
};

/* close the x25iface encapsulation protocol 
 */
static int isdn_x25iface_proto_close(struct concap_proto *cprot){

	ix25_pdata_t *tmp;
        int ret = 0;
	ulong flags;

	if( ! cprot ){
		printk( KERN_ERR "isdn_x25iface_proto_close: "
			"invalid concap_proto pointer\n" );
		return -1;
	}
	IX25DEBUG( "isdn_x25iface_proto_close %s \n", MY_DEVNAME(cprot -> net_dev) );
	spin_lock_irqsave(&cprot->lock, flags);
	cprot -> dops    = NULL;
	cprot -> net_dev = NULL;
	tmp = cprot -> proto_data;
	if( pdata_is_bad( tmp ) ){
		ret = -1;
	} else {
		tmp -> state = WAN_UNCONFIGURED;
	}
	spin_unlock_irqrestore(&cprot->lock, flags);
	return ret;
}

/* Delete the x25iface encapsulation protocol instance
 */
static void isdn_x25iface_proto_del(struct concap_proto *cprot){

	ix25_pdata_t * tmp;
 
	IX25DEBUG( "isdn_x25iface_proto_del \n" );
	if( ! cprot ){
		printk( KERN_ERR "isdn_x25iface_proto_del: "
			"concap_proto pointer is NULL\n" );
		return;
	}
	tmp = cprot -> proto_data;
	if( tmp == NULL ){ 
		printk( KERN_ERR "isdn_x25iface_proto_del: inconsistent "
			"proto_data pointer (maybe already deleted?)\n"); 
		return;
	}
	/* close if the protocol is still open */
	if( cprot -> dops ) isdn_x25iface_proto_close(cprot);
	/* freeing the storage should be sufficient now. But some additional
	   settings might help to catch wild pointer bugs */
	tmp -> magic = 0;
	cprot -> proto_data = NULL;

	kfree( tmp );
	return;
}

/* (re-)initialize the data structures for x25iface encapsulation
 */
static int isdn_x25iface_proto_restart(struct concap_proto *cprot,
					struct net_device *ndev,
					struct concap_device_ops *dops)
{
	ix25_pdata_t * pda = cprot -> proto_data ;
	ulong flags;

	IX25DEBUG( "isdn_x25iface_proto_restart %s \n", MY_DEVNAME(ndev) );

	if ( pdata_is_bad( pda ) ) return -1;

	if( !( dops  && dops -> data_req && dops -> connect_req 
	       && dops -> disconn_req )  ){
		printk( KERN_WARNING "isdn_x25iface_restart: required dops"
			" missing\n" );
		isdn_x25iface_proto_close(cprot);
		return -1;
	}
	spin_lock_irqsave(&cprot->lock, flags);
	cprot -> net_dev = ndev;
	cprot -> pops = &ix25_pops;
	cprot -> dops = dops;
	pda -> state = WAN_DISCONNECTED;
	spin_unlock_irqrestore(&cprot->lock, flags);
	return 0;
}

/* deliver a dl_data frame received from i4l HL driver to the network layer 
 */
static int isdn_x25iface_receive(struct concap_proto *cprot, struct sk_buff *skb)
{
  	IX25DEBUG( "isdn_x25iface_receive %s \n", MY_DEVNAME(cprot->net_dev) );
	if ( ( (ix25_pdata_t*) (cprot->proto_data) ) 
	     -> state == WAN_CONNECTED ){
		if( skb_push(skb, 1)){
			skb -> data[0]=0x00;
			skb->protocol = x25_type_trans(skb, cprot->net_dev);
			netif_rx(skb);
			return 0;
		}
	}
	printk(KERN_WARNING "isdn_x25iface_receive %s: not connected, skb dropped\n", MY_DEVNAME(cprot->net_dev) );
	dev_kfree_skb(skb);
	return -1;
}

/* a connection set up is indicated by lower layer 
 */
static int isdn_x25iface_connect_ind(struct concap_proto *cprot)
{
	struct sk_buff * skb = dev_alloc_skb(1);
	enum wan_states *state_p 
	  = &( ( (ix25_pdata_t*) (cprot->proto_data) ) -> state);
	IX25DEBUG( "isdn_x25iface_connect_ind %s \n"
		   , MY_DEVNAME(cprot->net_dev) );
	if( *state_p == WAN_UNCONFIGURED ){ 
		printk(KERN_WARNING 
		       "isdn_x25iface_connect_ind while unconfigured %s\n"
		       , MY_DEVNAME(cprot->net_dev) );
		return -1;
	}
	*state_p = WAN_CONNECTED;
	if( skb ){
		*( skb_put(skb, 1) ) = 0x01;
		skb->protocol = x25_type_trans(skb, cprot->net_dev);
		netif_rx(skb);
		return 0;
	} else {
		printk(KERN_WARNING "isdn_x25iface_connect_ind: "
		       " out of memory -- disconnecting\n");
		cprot -> dops -> disconn_req(cprot);
		return -1;
	}
}
	
/* a disconnect is indicated by lower layer 
 */
static int isdn_x25iface_disconn_ind(struct concap_proto *cprot)
{
	struct sk_buff *skb;
	enum wan_states *state_p 
	  = &( ( (ix25_pdata_t*) (cprot->proto_data) ) -> state);
	IX25DEBUG( "isdn_x25iface_disconn_ind %s \n", MY_DEVNAME(cprot -> net_dev) );
	if( *state_p == WAN_UNCONFIGURED ){ 
		printk(KERN_WARNING 
		       "isdn_x25iface_disconn_ind while unconfigured\n");
		return -1;
	}
	if(! cprot -> net_dev) return -1;
	*state_p = WAN_DISCONNECTED;
	skb = dev_alloc_skb(1);
	if( skb ){
		*( skb_put(skb, 1) ) = 0x02;
		skb->protocol = x25_type_trans(skb, cprot->net_dev);
		netif_rx(skb);
		return 0;
	} else {
		printk(KERN_WARNING "isdn_x25iface_disconn_ind:"
		       " out of memory\n");
		return -1;
	}
}

/* process a frame handed over to us from linux network layer. First byte
   semantics as defined in Documentation/networking/x25-iface.txt
   */
static int isdn_x25iface_xmit(struct concap_proto *cprot, struct sk_buff *skb)
{
	unsigned char firstbyte = skb->data[0];
	enum wan_states *state = &((ix25_pdata_t*)cprot->proto_data)->state;
	int ret = 0;
	IX25DEBUG( "isdn_x25iface_xmit: %s first=%x state=%d \n", MY_DEVNAME(cprot -> net_dev), firstbyte, *state );
	switch ( firstbyte ){
	case 0x00: /* dl_data request */
		if( *state == WAN_CONNECTED ){
			skb_pull(skb, 1);
			cprot -> net_dev -> trans_start = jiffies;
			ret = ( cprot -> dops -> data_req(cprot, skb) );
			/* prepare for future retransmissions */
			if( ret ) skb_push(skb,1);
			return ret;
		}
		illegal_state_warn( *state, firstbyte ); 
		break;
	case 0x01: /* dl_connect request */
		if( *state == WAN_DISCONNECTED ){
			*state = WAN_CONNECTING;
		        ret = cprot -> dops -> connect_req(cprot);
			if(ret){
				/* reset state and notify upper layer about
				 * immidiatly failed attempts */
				isdn_x25iface_disconn_ind(cprot);
			}
		} else {
			illegal_state_warn( *state, firstbyte );
		}
		break;
	case 0x02: /* dl_disconnect request */
		switch ( *state ){
		case WAN_DISCONNECTED: 
			/* Should not happen. However, give upper layer a
			   chance to recover from inconstistency  but don't
			   trust the lower layer sending the disconn_confirm
			   when already disconnected */
			printk(KERN_WARNING "isdn_x25iface_xmit: disconnect "
			       " requested while disconnected\n" );
			isdn_x25iface_disconn_ind(cprot);
			break; /* prevent infinite loops */
		case WAN_CONNECTING:
		case WAN_CONNECTED:
			*state = WAN_DISCONNECTED;
			cprot -> dops -> disconn_req(cprot);
			break;
		default:
			illegal_state_warn( *state, firstbyte );
		}
		break;
	case 0x03: /* changing lapb parameters requested */
		printk(KERN_WARNING "isdn_x25iface_xmit: setting of lapb"
		       " options not yet supported\n");
		break;
	default:
		printk(KERN_WARNING "isdn_x25iface_xmit: frame with illegal"
		       " first byte %x ignored:\n", firstbyte);
	}
	dev_kfree_skb(skb);
	return 0;
}
Commit	Line	Data
1da177e4 LT	1	/* $Id: isdn_x25iface.c,v 1.1.2.2 2004/01/12 22:37:19 keil Exp $
	2	*
	3	* Linux ISDN subsystem, X.25 related functions
	4	*
	5	* This software may be used and distributed according to the terms
	6	* of the GNU General Public License, incorporated herein by reference.
	7	*
	8	* stuff needed to support the Linux X.25 PLP code on top of devices that
	9	* can provide a lab_b service using the concap_proto mechanism.
c30fe7f7	10	* This module supports a network interface which provides lapb_sematics
1da177e4 LT	11	* -- as defined in Documentation/networking/x25-iface.txt -- to
	12	* the upper layer and assumes that the lower layer provides a reliable
	13	* data link service by means of the concap_device_ops callbacks.
	14	*
	15	* Only protocol specific stuff goes here. Device specific stuff
	16	* goes to another -- device related -- concap_proto support source file.
	17	*
	18	*/
	19
	20	/* #include <linux/isdn.h> */
	21	#include <linux/netdevice.h>
	22	#include <linux/concap.h>
	23	#include <linux/wanrouter.h>
	24	#include <net/x25device.h>
	25	#include "isdn_x25iface.h"
	26
	27	/* for debugging messages not to cause an oops when device pointer is NULL*/
	28	#define MY_DEVNAME(dev) ( (dev) ? (dev)->name : "DEVICE UNSPECIFIED" )
	29
	30
	31	typedef struct isdn_x25iface_proto_data {
	32	int magic;
	33	enum wan_states state;
	34	/* Private stuff, not to be accessed via proto_data. We provide the
	35	other storage for the concap_proto instance here as well,
	36	enabling us to allocate both with just one kmalloc(): */
	37	struct concap_proto priv;
	38	} ix25_pdata_t;
	39
	40
	41
	42	/* is now in header file (extern): struct concap_proto * isdn_x25iface_proto_new(void); */
3e206b0a AB	43	static void isdn_x25iface_proto_del( struct concap_proto * );
	44	static int isdn_x25iface_proto_close( struct concap_proto * );
	45	static int isdn_x25iface_proto_restart( struct concap_proto *,
	46	struct net_device *,
	47	struct concap_device_ops *);
	48	static int isdn_x25iface_xmit( struct concap_proto , struct sk_buff );
	49	static int isdn_x25iface_receive( struct concap_proto , struct sk_buff );
	50	static int isdn_x25iface_connect_ind( struct concap_proto * );
	51	static int isdn_x25iface_disconn_ind( struct concap_proto * );
1da177e4 LT	52
	53
	54	static struct concap_proto_ops ix25_pops = {
	55	&isdn_x25iface_proto_new,
	56	&isdn_x25iface_proto_del,
	57	&isdn_x25iface_proto_restart,
	58	&isdn_x25iface_proto_close,
	59	&isdn_x25iface_xmit,
	60	&isdn_x25iface_receive,
	61	&isdn_x25iface_connect_ind,
	62	&isdn_x25iface_disconn_ind
	63	};
	64
	65	/* error message helper function */
	66	static void illegal_state_warn( unsigned state, unsigned char firstbyte)
	67	{
	68	printk( KERN_WARNING "isdn_x25iface: firstbyte %x illegal in"
	69	"current state %d\n",firstbyte, state );
	70	}
	71
	72	/* check protocol data field for consistency */
	73	static int pdata_is_bad( ix25_pdata_t * pda ){
	74
	75	if( pda && pda -> magic == ISDN_X25IFACE_MAGIC ) return 0;
	76	printk( KERN_WARNING
	77	"isdn_x25iface_xxx: illegal pointer to proto data\n" );
	78	return 1;
	79	}
	80
	81	/* create a new x25 interface protocol instance
	82	*/
	83	struct concap_proto * isdn_x25iface_proto_new(void)
	84	{
	85	ix25_pdata_t * tmp = kmalloc(sizeof(ix25_pdata_t),GFP_KERNEL);
	86	IX25DEBUG("isdn_x25iface_proto_new\n");
	87	if( tmp ){
	88	tmp -> magic = ISDN_X25IFACE_MAGIC;
	89	tmp -> state = WAN_UNCONFIGURED;
	90	/* private data space used to hold the concap_proto data.
	91	Only to be accessed via the returned pointer */
	92	spin_lock_init(&tmp->priv.lock);
	93	tmp -> priv.dops = NULL;
	94	tmp -> priv.net_dev = NULL;
	95	tmp -> priv.pops = &ix25_pops;
	96	tmp -> priv.flags = 0;
	97	tmp -> priv.proto_data = tmp;
	98	return( &(tmp -> priv) );
	99	}
	100	return NULL;
	101	};
	102
	103	/* close the x25iface encapsulation protocol
	104	*/
3e206b0a	105	static int isdn_x25iface_proto_close(struct concap_proto *cprot){
1da177e4 LT	106
	107	ix25_pdata_t *tmp;
	108	int ret = 0;
	109	ulong flags;
	110
	111	if( ! cprot ){
	112	printk( KERN_ERR "isdn_x25iface_proto_close: "
	113	"invalid concap_proto pointer\n" );
	114	return -1;
	115	}
	116	IX25DEBUG( "isdn_x25iface_proto_close %s \n", MY_DEVNAME(cprot -> net_dev) );
	117	spin_lock_irqsave(&cprot->lock, flags);
	118	cprot -> dops = NULL;
	119	cprot -> net_dev = NULL;
	120	tmp = cprot -> proto_data;
	121	if( pdata_is_bad( tmp ) ){
	122	ret = -1;
	123	} else {
	124	tmp -> state = WAN_UNCONFIGURED;
	125	}
	126	spin_unlock_irqrestore(&cprot->lock, flags);
	127	return ret;
	128	}
	129
	130	/* Delete the x25iface encapsulation protocol instance
	131	*/
3e206b0a	132	static void isdn_x25iface_proto_del(struct concap_proto *cprot){
1da177e4 LT	133
	134	ix25_pdata_t * tmp;
	135
	136	IX25DEBUG( "isdn_x25iface_proto_del \n" );
	137	if( ! cprot ){
	138	printk( KERN_ERR "isdn_x25iface_proto_del: "
	139	"concap_proto pointer is NULL\n" );
	140	return;
	141	}
	142	tmp = cprot -> proto_data;
	143	if( tmp == NULL ){
	144	printk( KERN_ERR "isdn_x25iface_proto_del: inconsistent "
	145	"proto_data pointer (maybe already deleted?)\n");
	146	return;
	147	}
	148	/* close if the protocol is still open */
	149	if( cprot -> dops ) isdn_x25iface_proto_close(cprot);
	150	/* freeing the storage should be sufficient now. But some additional
	151	settings might help to catch wild pointer bugs */
	152	tmp -> magic = 0;
	153	cprot -> proto_data = NULL;
	154
	155	kfree( tmp );
	156	return;
	157	}
	158
	159	/* (re-)initialize the data structures for x25iface encapsulation
	160	*/
3e206b0a AB	161	static int isdn_x25iface_proto_restart(struct concap_proto *cprot,
	162	struct net_device *ndev,
	163	struct concap_device_ops *dops)
1da177e4 LT	164	{
	165	ix25_pdata_t * pda = cprot -> proto_data ;
	166	ulong flags;
	167
	168	IX25DEBUG( "isdn_x25iface_proto_restart %s \n", MY_DEVNAME(ndev) );
	169
	170	if ( pdata_is_bad( pda ) ) return -1;
	171
	172	if( !( dops && dops -> data_req && dops -> connect_req
	173	&& dops -> disconn_req ) ){
	174	printk( KERN_WARNING "isdn_x25iface_restart: required dops"
	175	" missing\n" );
	176	isdn_x25iface_proto_close(cprot);
	177	return -1;
	178	}
	179	spin_lock_irqsave(&cprot->lock, flags);
	180	cprot -> net_dev = ndev;
	181	cprot -> pops = &ix25_pops;
	182	cprot -> dops = dops;
	183	pda -> state = WAN_DISCONNECTED;
	184	spin_unlock_irqrestore(&cprot->lock, flags);
	185	return 0;
	186	}
	187
	188	/* deliver a dl_data frame received from i4l HL driver to the network layer
	189	*/
3e206b0a	190	static int isdn_x25iface_receive(struct concap_proto cprot, struct sk_buff skb)
1da177e4 LT	191	{
	192	IX25DEBUG( "isdn_x25iface_receive %s \n", MY_DEVNAME(cprot->net_dev) );
	193	if ( ( (ix25_pdata_t*) (cprot->proto_data) )
	194	-> state == WAN_CONNECTED ){
	195	if( skb_push(skb, 1)){
	196	skb -> data[0]=0x00;
	197	skb->protocol = x25_type_trans(skb, cprot->net_dev);
	198	netif_rx(skb);
	199	return 0;
	200	}
	201	}
	202	printk(KERN_WARNING "isdn_x25iface_receive %s: not connected, skb dropped\n", MY_DEVNAME(cprot->net_dev) );
	203	dev_kfree_skb(skb);
	204	return -1;
	205	}
	206
	207	/* a connection set up is indicated by lower layer
	208	*/
3e206b0a	209	static int isdn_x25iface_connect_ind(struct concap_proto *cprot)
1da177e4 LT	210	{
	211	struct sk_buff * skb = dev_alloc_skb(1);
	212	enum wan_states *state_p
	213	= &( ( (ix25_pdata_t*) (cprot->proto_data) ) -> state);
	214	IX25DEBUG( "isdn_x25iface_connect_ind %s \n"
	215	, MY_DEVNAME(cprot->net_dev) );
	216	if( *state_p == WAN_UNCONFIGURED ){
	217	printk(KERN_WARNING
	218	"isdn_x25iface_connect_ind while unconfigured %s\n"
	219	, MY_DEVNAME(cprot->net_dev) );
	220	return -1;
	221	}
	222	*state_p = WAN_CONNECTED;
	223	if( skb ){
	224	*( skb_put(skb, 1) ) = 0x01;
	225	skb->protocol = x25_type_trans(skb, cprot->net_dev);
	226	netif_rx(skb);
	227	return 0;
	228	} else {
	229	printk(KERN_WARNING "isdn_x25iface_connect_ind: "
	230	" out of memory -- disconnecting\n");
	231	cprot -> dops -> disconn_req(cprot);
	232	return -1;
	233	}
	234	}
	235
	236	/* a disconnect is indicated by lower layer
	237	*/
3e206b0a	238	static int isdn_x25iface_disconn_ind(struct concap_proto *cprot)
1da177e4 LT	239	{
	240	struct sk_buff *skb;
	241	enum wan_states *state_p
	242	= &( ( (ix25_pdata_t*) (cprot->proto_data) ) -> state);
	243	IX25DEBUG( "isdn_x25iface_disconn_ind %s \n", MY_DEVNAME(cprot -> net_dev) );
	244	if( *state_p == WAN_UNCONFIGURED ){
	245	printk(KERN_WARNING
	246	"isdn_x25iface_disconn_ind while unconfigured\n");
	247	return -1;
	248	}
	249	if(! cprot -> net_dev) return -1;
	250	*state_p = WAN_DISCONNECTED;
	251	skb = dev_alloc_skb(1);
	252	if( skb ){
	253	*( skb_put(skb, 1) ) = 0x02;
	254	skb->protocol = x25_type_trans(skb, cprot->net_dev);
	255	netif_rx(skb);
	256	return 0;
	257	} else {
	258	printk(KERN_WARNING "isdn_x25iface_disconn_ind:"
	259	" out of memory\n");
	260	return -1;
	261	}
	262	}
	263
	264	/* process a frame handed over to us from linux network layer. First byte
	265	semantics as defined in Documentation/networking/x25-iface.txt
	266	*/
3e206b0a	267	static int isdn_x25iface_xmit(struct concap_proto cprot, struct sk_buff skb)
1da177e4 LT	268	{
	269	unsigned char firstbyte = skb->data[0];
	270	enum wan_states state = &((ix25_pdata_t)cprot->proto_data)->state;
	271	int ret = 0;
	272	IX25DEBUG( "isdn_x25iface_xmit: %s first=%x state=%d \n", MY_DEVNAME(cprot -> net_dev), firstbyte, *state );
	273	switch ( firstbyte ){
	274	case 0x00: /* dl_data request */
	275	if( *state == WAN_CONNECTED ){
	276	skb_pull(skb, 1);
	277	cprot -> net_dev -> trans_start = jiffies;
	278	ret = ( cprot -> dops -> data_req(cprot, skb) );
	279	/* prepare for future retransmissions */
	280	if( ret ) skb_push(skb,1);
	281	return ret;
	282	}
	283	illegal_state_warn( *state, firstbyte );
	284	break;
	285	case 0x01: /* dl_connect request */
	286	if( *state == WAN_DISCONNECTED ){
	287	*state = WAN_CONNECTING;
	288	ret = cprot -> dops -> connect_req(cprot);
	289	if(ret){
	290	/* reset state and notify upper layer about
	291	* immidiatly failed attempts */
	292	isdn_x25iface_disconn_ind(cprot);
	293	}
	294	} else {
	295	illegal_state_warn( *state, firstbyte );
	296	}
	297	break;
	298	case 0x02: /* dl_disconnect request */
	299	switch ( *state ){
	300	case WAN_DISCONNECTED:
	301	/* Should not happen. However, give upper layer a
	302	chance to recover from inconstistency but don't
	303	trust the lower layer sending the disconn_confirm
	304	when already disconnected */
	305	printk(KERN_WARNING "isdn_x25iface_xmit: disconnect "
	306	" requested while disconnected\n" );
	307	isdn_x25iface_disconn_ind(cprot);
	308	break; /* prevent infinite loops */
	309	case WAN_CONNECTING:
	310	case WAN_CONNECTED:
	311	*state = WAN_DISCONNECTED;
	312	cprot -> dops -> disconn_req(cprot);
	313	break;
	314	default:
	315	illegal_state_warn( *state, firstbyte );
	316	}
	317	break;
	318	case 0x03: /* changing lapb parameters requested */
	319	printk(KERN_WARNING "isdn_x25iface_xmit: setting of lapb"
	320	" options not yet supported\n");
	321	break;
	322	default:
	323	printk(KERN_WARNING "isdn_x25iface_xmit: frame with illegal"
	324	" first byte %x ignored:\n", firstbyte);
	325	}
	326	dev_kfree_skb(skb);
	327	return 0;
	328	}