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 
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); */
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 *);
53 
54 
55 static struct concap_proto_ops ix25_pops = {
56 	.proto_new = &isdn_x25iface_proto_new,
57 	.proto_del = &isdn_x25iface_proto_del,
58 	.restart = &isdn_x25iface_proto_restart,
59 	.close = &isdn_x25iface_proto_close,
60 	.encap_and_xmit = &isdn_x25iface_xmit,
61 	.data_ind = &isdn_x25iface_receive,
62 	.connect_ind = &isdn_x25iface_connect_ind,
63 	.disconn_ind = &isdn_x25iface_disconn_ind
64 };
65 
66 /* error message helper function */
illegal_state_warn(unsigned state,unsigned char firstbyte)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 */
pdata_is_bad(ix25_pdata_t * pda)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  */
isdn_x25iface_proto_new(void)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  */
isdn_x25iface_proto_close(struct concap_proto * cprot)106 static 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  */
isdn_x25iface_proto_del(struct concap_proto * cprot)133 static 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  */
isdn_x25iface_proto_restart(struct concap_proto * cprot,struct net_device * ndev,struct concap_device_ops * dops)162 static 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  */
isdn_x25iface_receive(struct concap_proto * cprot,struct sk_buff * skb)191 static 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  */
isdn_x25iface_connect_ind(struct concap_proto * cprot)210 static 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_u8(skb, 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  */
isdn_x25iface_disconn_ind(struct concap_proto * cprot)241 static 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_u8(skb, 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 */
isdn_x25iface_xmit(struct concap_proto * cprot,struct sk_buff * skb)270 static 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 			netif_trans_update(cprot->net_dev);
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