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.
10 * This module supports a network interface which provides lapb_sematics
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/slab.h>
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
32typedef 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); */
44static void isdn_x25iface_proto_del(struct concap_proto *);
45static int isdn_x25iface_proto_close(struct concap_proto *);
46static int isdn_x25iface_proto_restart(struct concap_proto *,
47				       struct net_device *,
48				       struct concap_device_ops *);
49static int isdn_x25iface_xmit(struct concap_proto *, struct sk_buff *);
50static int isdn_x25iface_receive(struct concap_proto *, struct sk_buff *);
51static int isdn_x25iface_connect_ind(struct concap_proto *);
52static int isdn_x25iface_disconn_ind(struct concap_proto *);
53
54
55static 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 */
67static 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 */
74static 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 */
84struct 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 */
106static int isdn_x25iface_proto_close(struct concap_proto *cprot) {
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 */
133static void isdn_x25iface_proto_del(struct concap_proto *cprot) {
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 */
162static int isdn_x25iface_proto_restart(struct concap_proto *cprot,
163				       struct net_device *ndev,
164				       struct concap_device_ops *dops)
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 */
191static int isdn_x25iface_receive(struct concap_proto *cprot, struct sk_buff *skb)
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] = X25_IFACE_DATA;
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 */
210static int isdn_x25iface_connect_ind(struct concap_proto *cprot)
211{
212	struct sk_buff *skb;
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;
224
225	skb = dev_alloc_skb(1);
226	if (skb) {
227		*(skb_put(skb, 1)) = X25_IFACE_CONNECT;
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 */
241static int isdn_x25iface_disconn_ind(struct concap_proto *cprot)
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)) = X25_IFACE_DISCONNECT;
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*/
270static int isdn_x25iface_xmit(struct concap_proto *cprot, struct sk_buff *skb)
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",
276		  MY_DEVNAME(cprot->net_dev), firstbyte, *state);
277	switch (firstbyte) {
278	case X25_IFACE_DATA:
279		if (*state == WAN_CONNECTED) {
280			skb_pull(skb, 1);
281			cprot->net_dev->trans_start = jiffies;
282			ret = (cprot->dops->data_req(cprot, skb));
283			/* prepare for future retransmissions */
284			if (ret) skb_push(skb, 1);
285			return ret;
286		}
287		illegal_state_warn(*state, firstbyte);
288		break;
289	case X25_IFACE_CONNECT:
290		if (*state == WAN_DISCONNECTED) {
291			*state = WAN_CONNECTING;
292			ret = cprot->dops->connect_req(cprot);
293			if (ret) {
294				/* reset state and notify upper layer about
295				 * immidiatly failed attempts */
296				isdn_x25iface_disconn_ind(cprot);
297			}
298		} else {
299			illegal_state_warn(*state, firstbyte);
300		}
301		break;
302	case X25_IFACE_DISCONNECT:
303		switch (*state) {
304		case WAN_DISCONNECTED:
305			/* Should not happen. However, give upper layer a
306			   chance to recover from inconstistency  but don't
307			   trust the lower layer sending the disconn_confirm
308			   when already disconnected */
309			printk(KERN_WARNING "isdn_x25iface_xmit: disconnect "
310			       " requested while disconnected\n");
311			isdn_x25iface_disconn_ind(cprot);
312			break; /* prevent infinite loops */
313		case WAN_CONNECTING:
314		case WAN_CONNECTED:
315			*state = WAN_DISCONNECTED;
316			cprot->dops->disconn_req(cprot);
317			break;
318		default:
319			illegal_state_warn(*state, firstbyte);
320		}
321		break;
322	case X25_IFACE_PARAMS:
323		printk(KERN_WARNING "isdn_x25iface_xmit: setting of lapb"
324		       " options not yet supported\n");
325		break;
326	default:
327		printk(KERN_WARNING "isdn_x25iface_xmit: frame with illegal"
328		       " first byte %x ignored:\n", firstbyte);
329	}
330	dev_kfree_skb(skb);
331	return 0;
332}
333