1 /*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
8 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
9 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
10 */
11 #include <linux/errno.h>
12 #include <linux/types.h>
13 #include <linux/socket.h>
14 #include <linux/in.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/timer.h>
18 #include <linux/string.h>
19 #include <linux/sockios.h>
20 #include <linux/spinlock.h>
21 #include <linux/net.h>
22 #include <linux/slab.h>
23 #include <net/ax25.h>
24 #include <linux/inet.h>
25 #include <linux/netdevice.h>
26 #include <linux/skbuff.h>
27 #include <net/sock.h>
28 #include <linux/uaccess.h>
29 #include <linux/fcntl.h>
30 #include <linux/mm.h>
31 #include <linux/interrupt.h>
32
33 static DEFINE_SPINLOCK(ax25_frag_lock);
34
ax25_send_frame(struct sk_buff * skb,int paclen,ax25_address * src,ax25_address * dest,ax25_digi * digi,struct net_device * dev)35 ax25_cb *ax25_send_frame(struct sk_buff *skb, int paclen, ax25_address *src, ax25_address *dest, ax25_digi *digi, struct net_device *dev)
36 {
37 ax25_dev *ax25_dev;
38 ax25_cb *ax25;
39
40 /*
41 * Take the default packet length for the device if zero is
42 * specified.
43 */
44 if (paclen == 0) {
45 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
46 return NULL;
47
48 paclen = ax25_dev->values[AX25_VALUES_PACLEN];
49 }
50
51 /*
52 * Look for an existing connection.
53 */
54 if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) {
55 ax25_output(ax25, paclen, skb);
56 return ax25; /* It already existed */
57 }
58
59 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
60 return NULL;
61
62 if ((ax25 = ax25_create_cb()) == NULL)
63 return NULL;
64
65 ax25_fillin_cb(ax25, ax25_dev);
66
67 ax25->source_addr = *src;
68 ax25->dest_addr = *dest;
69
70 if (digi != NULL) {
71 ax25->digipeat = kmemdup(digi, sizeof(*digi), GFP_ATOMIC);
72 if (ax25->digipeat == NULL) {
73 ax25_cb_put(ax25);
74 return NULL;
75 }
76 }
77
78 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
79 case AX25_PROTO_STD_SIMPLEX:
80 case AX25_PROTO_STD_DUPLEX:
81 ax25_std_establish_data_link(ax25);
82 break;
83
84 #ifdef CONFIG_AX25_DAMA_SLAVE
85 case AX25_PROTO_DAMA_SLAVE:
86 if (ax25_dev->dama.slave)
87 ax25_ds_establish_data_link(ax25);
88 else
89 ax25_std_establish_data_link(ax25);
90 break;
91 #endif
92 }
93
94 /*
95 * There is one ref for the state machine; a caller needs
96 * one more to put it back, just like with the existing one.
97 */
98 ax25_cb_hold(ax25);
99
100 ax25_cb_add(ax25);
101
102 ax25->state = AX25_STATE_1;
103
104 ax25_start_heartbeat(ax25);
105
106 ax25_output(ax25, paclen, skb);
107
108 return ax25; /* We had to create it */
109 }
110
111 EXPORT_SYMBOL(ax25_send_frame);
112
113 /*
114 * All outgoing AX.25 I frames pass via this routine. Therefore this is
115 * where the fragmentation of frames takes place. If fragment is set to
116 * zero then we are not allowed to do fragmentation, even if the frame
117 * is too large.
118 */
ax25_output(ax25_cb * ax25,int paclen,struct sk_buff * skb)119 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
120 {
121 struct sk_buff *skbn;
122 unsigned char *p;
123 int frontlen, len, fragno, ka9qfrag, first = 1;
124
125 if (paclen < 16) {
126 WARN_ON_ONCE(1);
127 kfree_skb(skb);
128 return;
129 }
130
131 if ((skb->len - 1) > paclen) {
132 if (*skb->data == AX25_P_TEXT) {
133 skb_pull(skb, 1); /* skip PID */
134 ka9qfrag = 0;
135 } else {
136 paclen -= 2; /* Allow for fragment control info */
137 ka9qfrag = 1;
138 }
139
140 fragno = skb->len / paclen;
141 if (skb->len % paclen == 0) fragno--;
142
143 frontlen = skb_headroom(skb); /* Address space + CTRL */
144
145 while (skb->len > 0) {
146 spin_lock_bh(&ax25_frag_lock);
147 if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
148 spin_unlock_bh(&ax25_frag_lock);
149 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
150 return;
151 }
152
153 if (skb->sk != NULL)
154 skb_set_owner_w(skbn, skb->sk);
155
156 spin_unlock_bh(&ax25_frag_lock);
157
158 len = (paclen > skb->len) ? skb->len : paclen;
159
160 if (ka9qfrag == 1) {
161 skb_reserve(skbn, frontlen + 2);
162 skb_set_network_header(skbn,
163 skb_network_offset(skb));
164 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
165 p = skb_push(skbn, 2);
166
167 *p++ = AX25_P_SEGMENT;
168
169 *p = fragno--;
170 if (first) {
171 *p |= AX25_SEG_FIRST;
172 first = 0;
173 }
174 } else {
175 skb_reserve(skbn, frontlen + 1);
176 skb_set_network_header(skbn,
177 skb_network_offset(skb));
178 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
179 p = skb_push(skbn, 1);
180 *p = AX25_P_TEXT;
181 }
182
183 skb_pull(skb, len);
184 skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
185 }
186
187 kfree_skb(skb);
188 } else {
189 skb_queue_tail(&ax25->write_queue, skb); /* Throw it on the queue */
190 }
191
192 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
193 case AX25_PROTO_STD_SIMPLEX:
194 case AX25_PROTO_STD_DUPLEX:
195 ax25_kick(ax25);
196 break;
197
198 #ifdef CONFIG_AX25_DAMA_SLAVE
199 /*
200 * A DAMA slave is _required_ to work as normal AX.25L2V2
201 * if no DAMA master is available.
202 */
203 case AX25_PROTO_DAMA_SLAVE:
204 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
205 break;
206 #endif
207 }
208 }
209
210 /*
211 * This procedure is passed a buffer descriptor for an iframe. It builds
212 * the rest of the control part of the frame and then writes it out.
213 */
ax25_send_iframe(ax25_cb * ax25,struct sk_buff * skb,int poll_bit)214 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
215 {
216 unsigned char *frame;
217
218 if (skb == NULL)
219 return;
220
221 skb_reset_network_header(skb);
222
223 if (ax25->modulus == AX25_MODULUS) {
224 frame = skb_push(skb, 1);
225
226 *frame = AX25_I;
227 *frame |= (poll_bit) ? AX25_PF : 0;
228 *frame |= (ax25->vr << 5);
229 *frame |= (ax25->vs << 1);
230 } else {
231 frame = skb_push(skb, 2);
232
233 frame[0] = AX25_I;
234 frame[0] |= (ax25->vs << 1);
235 frame[1] = (poll_bit) ? AX25_EPF : 0;
236 frame[1] |= (ax25->vr << 1);
237 }
238
239 ax25_start_idletimer(ax25);
240
241 ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
242 }
243
ax25_kick(ax25_cb * ax25)244 void ax25_kick(ax25_cb *ax25)
245 {
246 struct sk_buff *skb, *skbn;
247 int last = 1;
248 unsigned short start, end, next;
249
250 if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
251 return;
252
253 if (ax25->condition & AX25_COND_PEER_RX_BUSY)
254 return;
255
256 if (skb_peek(&ax25->write_queue) == NULL)
257 return;
258
259 start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
260 end = (ax25->va + ax25->window) % ax25->modulus;
261
262 if (start == end)
263 return;
264
265 /*
266 * Transmit data until either we're out of data to send or
267 * the window is full. Send a poll on the final I frame if
268 * the window is filled.
269 */
270
271 /*
272 * Dequeue the frame and copy it.
273 * Check for race with ax25_clear_queues().
274 */
275 skb = skb_dequeue(&ax25->write_queue);
276 if (!skb)
277 return;
278
279 ax25->vs = start;
280
281 do {
282 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
283 skb_queue_head(&ax25->write_queue, skb);
284 break;
285 }
286
287 if (skb->sk != NULL)
288 skb_set_owner_w(skbn, skb->sk);
289
290 next = (ax25->vs + 1) % ax25->modulus;
291 last = (next == end);
292
293 /*
294 * Transmit the frame copy.
295 * bke 960114: do not set the Poll bit on the last frame
296 * in DAMA mode.
297 */
298 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
299 case AX25_PROTO_STD_SIMPLEX:
300 case AX25_PROTO_STD_DUPLEX:
301 ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
302 break;
303
304 #ifdef CONFIG_AX25_DAMA_SLAVE
305 case AX25_PROTO_DAMA_SLAVE:
306 ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
307 break;
308 #endif
309 }
310
311 ax25->vs = next;
312
313 /*
314 * Requeue the original data frame.
315 */
316 skb_queue_tail(&ax25->ack_queue, skb);
317
318 } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
319
320 ax25->condition &= ~AX25_COND_ACK_PENDING;
321
322 if (!ax25_t1timer_running(ax25)) {
323 ax25_stop_t3timer(ax25);
324 ax25_calculate_t1(ax25);
325 ax25_start_t1timer(ax25);
326 }
327 }
328
ax25_transmit_buffer(ax25_cb * ax25,struct sk_buff * skb,int type)329 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
330 {
331 struct sk_buff *skbn;
332 unsigned char *ptr;
333 int headroom;
334
335 if (ax25->ax25_dev == NULL) {
336 ax25_disconnect(ax25, ENETUNREACH);
337 return;
338 }
339
340 headroom = ax25_addr_size(ax25->digipeat);
341
342 if (skb_headroom(skb) < headroom) {
343 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
344 printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
345 kfree_skb(skb);
346 return;
347 }
348
349 if (skb->sk != NULL)
350 skb_set_owner_w(skbn, skb->sk);
351
352 consume_skb(skb);
353 skb = skbn;
354 }
355
356 ptr = skb_push(skb, headroom);
357
358 ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
359
360 ax25_queue_xmit(skb, ax25->ax25_dev->dev);
361 }
362
363 /*
364 * A small shim to dev_queue_xmit to add the KISS control byte, and do
365 * any packet forwarding in operation.
366 */
ax25_queue_xmit(struct sk_buff * skb,struct net_device * dev)367 void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev)
368 {
369 unsigned char *ptr;
370
371 skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));
372
373 ptr = skb_push(skb, 1);
374 *ptr = 0x00; /* KISS */
375
376 dev_queue_xmit(skb);
377 }
378
ax25_check_iframes_acked(ax25_cb * ax25,unsigned short nr)379 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
380 {
381 if (ax25->vs == nr) {
382 ax25_frames_acked(ax25, nr);
383 ax25_calculate_rtt(ax25);
384 ax25_stop_t1timer(ax25);
385 ax25_start_t3timer(ax25);
386 return 1;
387 } else {
388 if (ax25->va != nr) {
389 ax25_frames_acked(ax25, nr);
390 ax25_calculate_t1(ax25);
391 ax25_start_t1timer(ax25);
392 return 1;
393 }
394 }
395 return 0;
396 }
397
