e33fa3073f74b100616e5d0756721c3906b854c4
[sfrench/cifs-2.6.git] / drivers / isdn / i4l / isdn_x25iface.c
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 */
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  */
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  */
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  */
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  */
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  */
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                 *(u8 *)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  */
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                 *(u8 *)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 */
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 }