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