[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/slab.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;
	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;

	skb = dev_alloc_skb(1);
	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>
5a0e3ad6	23	#include <linux/slab.h>
1da177e4 LT	24	#include <linux/wanrouter.h>
	25	#include <net/x25device.h>
	26	#include "isdn_x25iface.h"
	27
	28	/* for debugging messages not to cause an oops when device pointer is NULL*/
	29	#define MY_DEVNAME(dev) ( (dev) ? (dev)->name : "DEVICE UNSPECIFIED" )
	30
	31
	32	typedef struct isdn_x25iface_proto_data {
	33	int magic;
	34	enum wan_states state;
	35	/* Private stuff, not to be accessed via proto_data. We provide the
	36	other storage for the concap_proto instance here as well,
	37	enabling us to allocate both with just one kmalloc(): */
	38	struct concap_proto priv;
	39	} ix25_pdata_t;
	40
	41
	42
	43	/* is now in header file (extern): struct concap_proto * isdn_x25iface_proto_new(void); */
3e206b0a AB	44	static void isdn_x25iface_proto_del( struct concap_proto * );
	45	static int isdn_x25iface_proto_close( struct concap_proto * );
	46	static int isdn_x25iface_proto_restart( struct concap_proto *,
	47	struct net_device *,
	48	struct concap_device_ops *);
	49	static int isdn_x25iface_xmit( struct concap_proto , struct sk_buff );
	50	static int isdn_x25iface_receive( struct concap_proto , struct sk_buff );
	51	static int isdn_x25iface_connect_ind( struct concap_proto * );
	52	static int isdn_x25iface_disconn_ind( struct concap_proto * );
1da177e4 LT	53
	54
	55	static struct concap_proto_ops ix25_pops = {
	56	&isdn_x25iface_proto_new,
	57	&isdn_x25iface_proto_del,
	58	&isdn_x25iface_proto_restart,
	59	&isdn_x25iface_proto_close,
	60	&isdn_x25iface_xmit,
	61	&isdn_x25iface_receive,
	62	&isdn_x25iface_connect_ind,
	63	&isdn_x25iface_disconn_ind
	64	};
	65
	66	/* error message helper function */
	67	static void illegal_state_warn( unsigned state, unsigned char firstbyte)
	68	{
	69	printk( KERN_WARNING "isdn_x25iface: firstbyte %x illegal in"
	70	"current state %d\n",firstbyte, state );
	71	}
	72
	73	/* check protocol data field for consistency */
	74	static int pdata_is_bad( ix25_pdata_t * pda ){
	75
	76	if( pda && pda -> magic == ISDN_X25IFACE_MAGIC ) return 0;
	77	printk( KERN_WARNING
	78	"isdn_x25iface_xxx: illegal pointer to proto data\n" );
	79	return 1;
	80	}
	81
	82	/* create a new x25 interface protocol instance
	83	*/
	84	struct concap_proto * isdn_x25iface_proto_new(void)
	85	{
	86	ix25_pdata_t * tmp = kmalloc(sizeof(ix25_pdata_t),GFP_KERNEL);
	87	IX25DEBUG("isdn_x25iface_proto_new\n");
	88	if( tmp ){
	89	tmp -> magic = ISDN_X25IFACE_MAGIC;
	90	tmp -> state = WAN_UNCONFIGURED;
	91	/* private data space used to hold the concap_proto data.
	92	Only to be accessed via the returned pointer */
	93	spin_lock_init(&tmp->priv.lock);
	94	tmp -> priv.dops = NULL;
	95	tmp -> priv.net_dev = NULL;
	96	tmp -> priv.pops = &ix25_pops;
	97	tmp -> priv.flags = 0;
	98	tmp -> priv.proto_data = tmp;
	99	return( &(tmp -> priv) );
	100	}
	101	return NULL;
	102	};
	103
	104	/* close the x25iface encapsulation protocol
	105	*/
3e206b0a	106	static int isdn_x25iface_proto_close(struct concap_proto *cprot){
1da177e4 LT	107
	108	ix25_pdata_t *tmp;
	109	int ret = 0;
	110	ulong flags;
	111
	112	if( ! cprot ){
	113	printk( KERN_ERR "isdn_x25iface_proto_close: "
	114	"invalid concap_proto pointer\n" );
	115	return -1;
	116	}
	117	IX25DEBUG( "isdn_x25iface_proto_close %s \n", MY_DEVNAME(cprot -> net_dev) );
	118	spin_lock_irqsave(&cprot->lock, flags);
	119	cprot -> dops = NULL;
	120	cprot -> net_dev = NULL;
	121	tmp = cprot -> proto_data;
	122	if( pdata_is_bad( tmp ) ){
	123	ret = -1;
	124	} else {
	125	tmp -> state = WAN_UNCONFIGURED;
	126	}
	127	spin_unlock_irqrestore(&cprot->lock, flags);
	128	return ret;
	129	}
	130
	131	/* Delete the x25iface encapsulation protocol instance
	132	*/
3e206b0a	133	static void isdn_x25iface_proto_del(struct concap_proto *cprot){
1da177e4 LT	134
	135	ix25_pdata_t * tmp;
	136
	137	IX25DEBUG( "isdn_x25iface_proto_del \n" );
	138	if( ! cprot ){
	139	printk( KERN_ERR "isdn_x25iface_proto_del: "
	140	"concap_proto pointer is NULL\n" );
	141	return;
	142	}
	143	tmp = cprot -> proto_data;
	144	if( tmp == NULL ){
	145	printk( KERN_ERR "isdn_x25iface_proto_del: inconsistent "
	146	"proto_data pointer (maybe already deleted?)\n");
	147	return;
	148	}
	149	/* close if the protocol is still open */
	150	if( cprot -> dops ) isdn_x25iface_proto_close(cprot);
	151	/* freeing the storage should be sufficient now. But some additional
	152	settings might help to catch wild pointer bugs */
	153	tmp -> magic = 0;
	154	cprot -> proto_data = NULL;
	155
	156	kfree( tmp );
	157	return;
	158	}
	159
	160	/* (re-)initialize the data structures for x25iface encapsulation
	161	*/
3e206b0a AB	162	static int isdn_x25iface_proto_restart(struct concap_proto *cprot,
	163	struct net_device *ndev,
	164	struct concap_device_ops *dops)
1da177e4 LT	165	{
	166	ix25_pdata_t * pda = cprot -> proto_data ;
	167	ulong flags;
	168
	169	IX25DEBUG( "isdn_x25iface_proto_restart %s \n", MY_DEVNAME(ndev) );
	170
	171	if ( pdata_is_bad( pda ) ) return -1;
	172
	173	if( !( dops && dops -> data_req && dops -> connect_req
	174	&& dops -> disconn_req ) ){
	175	printk( KERN_WARNING "isdn_x25iface_restart: required dops"
	176	" missing\n" );
	177	isdn_x25iface_proto_close(cprot);
	178	return -1;
	179	}
	180	spin_lock_irqsave(&cprot->lock, flags);
	181	cprot -> net_dev = ndev;
	182	cprot -> pops = &ix25_pops;
	183	cprot -> dops = dops;
	184	pda -> state = WAN_DISCONNECTED;
	185	spin_unlock_irqrestore(&cprot->lock, flags);
	186	return 0;
	187	}
	188
	189	/* deliver a dl_data frame received from i4l HL driver to the network layer
	190	*/
3e206b0a	191	static int isdn_x25iface_receive(struct concap_proto cprot, struct sk_buff skb)
1da177e4 LT	192	{
	193	IX25DEBUG( "isdn_x25iface_receive %s \n", MY_DEVNAME(cprot->net_dev) );
	194	if ( ( (ix25_pdata_t*) (cprot->proto_data) )
	195	-> state == WAN_CONNECTED ){
	196	if( skb_push(skb, 1)){
	197	skb -> data[0]=0x00;
	198	skb->protocol = x25_type_trans(skb, cprot->net_dev);
	199	netif_rx(skb);
	200	return 0;
	201	}
	202	}
	203	printk(KERN_WARNING "isdn_x25iface_receive %s: not connected, skb dropped\n", MY_DEVNAME(cprot->net_dev) );
	204	dev_kfree_skb(skb);
	205	return -1;
	206	}
	207
	208	/* a connection set up is indicated by lower layer
	209	*/
3e206b0a	210	static int isdn_x25iface_connect_ind(struct concap_proto *cprot)
1da177e4	211	{
d81931d9	212	struct sk_buff * skb;
1da177e4 LT	213	enum wan_states *state_p
	214	= &( ( (ix25_pdata_t*) (cprot->proto_data) ) -> state);
	215	IX25DEBUG( "isdn_x25iface_connect_ind %s \n"
	216	, MY_DEVNAME(cprot->net_dev) );
	217	if( *state_p == WAN_UNCONFIGURED ){
	218	printk(KERN_WARNING
	219	"isdn_x25iface_connect_ind while unconfigured %s\n"
	220	, MY_DEVNAME(cprot->net_dev) );
	221	return -1;
	222	}
	223	*state_p = WAN_CONNECTED;
d81931d9 ES	224
d81931d9 ES	225	skb = dev_alloc_skb(1);
1da177e4 LT	226	if( skb ){
	227	*( skb_put(skb, 1) ) = 0x01;
	228	skb->protocol = x25_type_trans(skb, cprot->net_dev);
	229	netif_rx(skb);
	230	return 0;
	231	} else {
	232	printk(KERN_WARNING "isdn_x25iface_connect_ind: "
	233	" out of memory -- disconnecting\n");
	234	cprot -> dops -> disconn_req(cprot);
	235	return -1;
	236	}
	237	}
	238
	239	/* a disconnect is indicated by lower layer
	240	*/
3e206b0a	241	static int isdn_x25iface_disconn_ind(struct concap_proto *cprot)
1da177e4 LT	242	{
	243	struct sk_buff *skb;
	244	enum wan_states *state_p
	245	= &( ( (ix25_pdata_t*) (cprot->proto_data) ) -> state);
	246	IX25DEBUG( "isdn_x25iface_disconn_ind %s \n", MY_DEVNAME(cprot -> net_dev) );
	247	if( *state_p == WAN_UNCONFIGURED ){
	248	printk(KERN_WARNING
	249	"isdn_x25iface_disconn_ind while unconfigured\n");
	250	return -1;
	251	}
	252	if(! cprot -> net_dev) return -1;
	253	*state_p = WAN_DISCONNECTED;
	254	skb = dev_alloc_skb(1);
	255	if( skb ){
	256	*( skb_put(skb, 1) ) = 0x02;
	257	skb->protocol = x25_type_trans(skb, cprot->net_dev);
	258	netif_rx(skb);
	259	return 0;
	260	} else {
	261	printk(KERN_WARNING "isdn_x25iface_disconn_ind:"
	262	" out of memory\n");
	263	return -1;
	264	}
	265	}
	266
	267	/* process a frame handed over to us from linux network layer. First byte
	268	semantics as defined in Documentation/networking/x25-iface.txt
	269	*/
3e206b0a	270	static int isdn_x25iface_xmit(struct concap_proto cprot, struct sk_buff skb)
1da177e4 LT	271	{
	272	unsigned char firstbyte = skb->data[0];
	273	enum wan_states state = &((ix25_pdata_t)cprot->proto_data)->state;
	274	int ret = 0;
	275	IX25DEBUG( "isdn_x25iface_xmit: %s first=%x state=%d \n", MY_DEVNAME(cprot -> net_dev), firstbyte, *state );
	276	switch ( firstbyte ){
	277	case 0x00: /* dl_data request */
	278	if( *state == WAN_CONNECTED ){
	279	skb_pull(skb, 1);
	280	cprot -> net_dev -> trans_start = jiffies;
	281	ret = ( cprot -> dops -> data_req(cprot, skb) );
	282	/* prepare for future retransmissions */
	283	if( ret ) skb_push(skb,1);
	284	return ret;
	285	}
	286	illegal_state_warn( *state, firstbyte );
	287	break;
	288	case 0x01: /* dl_connect request */
	289	if( *state == WAN_DISCONNECTED ){
	290	*state = WAN_CONNECTING;
	291	ret = cprot -> dops -> connect_req(cprot);
	292	if(ret){
	293	/* reset state and notify upper layer about
	294	* immidiatly failed attempts */
	295	isdn_x25iface_disconn_ind(cprot);
	296	}
	297	} else {
	298	illegal_state_warn( *state, firstbyte );
	299	}
	300	break;
	301	case 0x02: /* dl_disconnect request */
	302	switch ( *state ){
	303	case WAN_DISCONNECTED:
	304	/* Should not happen. However, give upper layer a
	305	chance to recover from inconstistency but don't
	306	trust the lower layer sending the disconn_confirm
	307	when already disconnected */
	308	printk(KERN_WARNING "isdn_x25iface_xmit: disconnect "
	309	" requested while disconnected\n" );
	310	isdn_x25iface_disconn_ind(cprot);
	311	break; /* prevent infinite loops */
	312	case WAN_CONNECTING:
	313	case WAN_CONNECTED:
	314	*state = WAN_DISCONNECTED;
	315	cprot -> dops -> disconn_req(cprot);
	316	break;
	317	default:
	318	illegal_state_warn( *state, firstbyte );
	319	}
	320	break;
	321	case 0x03: /* changing lapb parameters requested */
	322	printk(KERN_WARNING "isdn_x25iface_xmit: setting of lapb"
	323	" options not yet supported\n");
	324	break;
	325	default:
	326	printk(KERN_WARNING "isdn_x25iface_xmit: frame with illegal"
	327	" first byte %x ignored:\n", firstbyte);
	328	}
	329	dev_kfree_skb(skb);
	330	return 0;
	331	}