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TOMOYO Linux Cross Reference
Linux/net/ax25/ax25_out.c

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  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 
 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  */
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  */
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 
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 
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  */
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 
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 

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