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 <linux/netfilter.h>
28#include <net/sock.h>
29#include <asm/uaccess.h>
30#include <linux/fcntl.h>
31#include <linux/mm.h>
32#include <linux/interrupt.h>
33
34static DEFINE_SPINLOCK(ax25_frag_lock);
35
36ax25_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	/*
96	 * There is one ref for the state machine; a caller needs
97	 * one more to put it back, just like with the existing one.
98	 */
99	ax25_cb_hold(ax25);
100
101	ax25_cb_add(ax25);
102
103	ax25->state = AX25_STATE_1;
104
105	ax25_start_heartbeat(ax25);
106
107	ax25_output(ax25, paclen, skb);
108
109	return ax25;			/* We had to create it */
110}
111
112EXPORT_SYMBOL(ax25_send_frame);
113
114/*
115 *	All outgoing AX.25 I frames pass via this routine. Therefore this is
116 *	where the fragmentation of frames takes place. If fragment is set to
117 *	zero then we are not allowed to do fragmentation, even if the frame
118 *	is too large.
119 */
120void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
121{
122	struct sk_buff *skbn;
123	unsigned char *p;
124	int frontlen, len, fragno, ka9qfrag, first = 1;
125
126	if (paclen < 16) {
127		WARN_ON_ONCE(1);
128		kfree_skb(skb);
129		return;
130	}
131
132	if ((skb->len - 1) > paclen) {
133		if (*skb->data == AX25_P_TEXT) {
134			skb_pull(skb, 1); /* skip PID */
135			ka9qfrag = 0;
136		} else {
137			paclen -= 2;	/* Allow for fragment control info */
138			ka9qfrag = 1;
139		}
140
141		fragno = skb->len / paclen;
142		if (skb->len % paclen == 0) fragno--;
143
144		frontlen = skb_headroom(skb);	/* Address space + CTRL */
145
146		while (skb->len > 0) {
147			spin_lock_bh(&ax25_frag_lock);
148			if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
149				spin_unlock_bh(&ax25_frag_lock);
150				printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
151				return;
152			}
153
154			if (skb->sk != NULL)
155				skb_set_owner_w(skbn, skb->sk);
156
157			spin_unlock_bh(&ax25_frag_lock);
158
159			len = (paclen > skb->len) ? skb->len : paclen;
160
161			if (ka9qfrag == 1) {
162				skb_reserve(skbn, frontlen + 2);
163				skb_set_network_header(skbn,
164						      skb_network_offset(skb));
165				skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
166				p = skb_push(skbn, 2);
167
168				*p++ = AX25_P_SEGMENT;
169
170				*p = fragno--;
171				if (first) {
172					*p |= AX25_SEG_FIRST;
173					first = 0;
174				}
175			} else {
176				skb_reserve(skbn, frontlen + 1);
177				skb_set_network_header(skbn,
178						      skb_network_offset(skb));
179				skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
180				p = skb_push(skbn, 1);
181				*p = AX25_P_TEXT;
182			}
183
184			skb_pull(skb, len);
185			skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
186		}
187
188		kfree_skb(skb);
189	} else {
190		skb_queue_tail(&ax25->write_queue, skb);	  /* Throw it on the queue */
191	}
192
193	switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
194	case AX25_PROTO_STD_SIMPLEX:
195	case AX25_PROTO_STD_DUPLEX:
196		ax25_kick(ax25);
197		break;
198
199#ifdef CONFIG_AX25_DAMA_SLAVE
200	/*
201	 * A DAMA slave is _required_ to work as normal AX.25L2V2
202	 * if no DAMA master is available.
203	 */
204	case AX25_PROTO_DAMA_SLAVE:
205		if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
206		break;
207#endif
208	}
209}
210
211/*
212 *  This procedure is passed a buffer descriptor for an iframe. It builds
213 *  the rest of the control part of the frame and then writes it out.
214 */
215static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
216{
217	unsigned char *frame;
218
219	if (skb == NULL)
220		return;
221
222	skb_reset_network_header(skb);
223
224	if (ax25->modulus == AX25_MODULUS) {
225		frame = skb_push(skb, 1);
226
227		*frame = AX25_I;
228		*frame |= (poll_bit) ? AX25_PF : 0;
229		*frame |= (ax25->vr << 5);
230		*frame |= (ax25->vs << 1);
231	} else {
232		frame = skb_push(skb, 2);
233
234		frame[0] = AX25_I;
235		frame[0] |= (ax25->vs << 1);
236		frame[1] = (poll_bit) ? AX25_EPF : 0;
237		frame[1] |= (ax25->vr << 1);
238	}
239
240	ax25_start_idletimer(ax25);
241
242	ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
243}
244
245void ax25_kick(ax25_cb *ax25)
246{
247	struct sk_buff *skb, *skbn;
248	int last = 1;
249	unsigned short start, end, next;
250
251	if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
252		return;
253
254	if (ax25->condition & AX25_COND_PEER_RX_BUSY)
255		return;
256
257	if (skb_peek(&ax25->write_queue) == NULL)
258		return;
259
260	start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
261	end   = (ax25->va + ax25->window) % ax25->modulus;
262
263	if (start == end)
264		return;
265
266	/*
267	 * Transmit data until either we're out of data to send or
268	 * the window is full. Send a poll on the final I frame if
269	 * the window is filled.
270	 */
271
272	/*
273	 * Dequeue the frame and copy it.
274	 * Check for race with ax25_clear_queues().
275	 */
276	skb  = skb_dequeue(&ax25->write_queue);
277	if (!skb)
278		return;
279
280	ax25->vs = start;
281
282	do {
283		if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
284			skb_queue_head(&ax25->write_queue, skb);
285			break;
286		}
287
288		if (skb->sk != NULL)
289			skb_set_owner_w(skbn, skb->sk);
290
291		next = (ax25->vs + 1) % ax25->modulus;
292		last = (next == end);
293
294		/*
295		 * Transmit the frame copy.
296		 * bke 960114: do not set the Poll bit on the last frame
297		 * in DAMA mode.
298		 */
299		switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
300		case AX25_PROTO_STD_SIMPLEX:
301		case AX25_PROTO_STD_DUPLEX:
302			ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
303			break;
304
305#ifdef CONFIG_AX25_DAMA_SLAVE
306		case AX25_PROTO_DAMA_SLAVE:
307			ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
308			break;
309#endif
310		}
311
312		ax25->vs = next;
313
314		/*
315		 * Requeue the original data frame.
316		 */
317		skb_queue_tail(&ax25->ack_queue, skb);
318
319	} while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
320
321	ax25->condition &= ~AX25_COND_ACK_PENDING;
322
323	if (!ax25_t1timer_running(ax25)) {
324		ax25_stop_t3timer(ax25);
325		ax25_calculate_t1(ax25);
326		ax25_start_t1timer(ax25);
327	}
328}
329
330void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
331{
332	struct sk_buff *skbn;
333	unsigned char *ptr;
334	int headroom;
335
336	if (ax25->ax25_dev == NULL) {
337		ax25_disconnect(ax25, ENETUNREACH);
338		return;
339	}
340
341	headroom = ax25_addr_size(ax25->digipeat);
342
343	if (skb_headroom(skb) < headroom) {
344		if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
345			printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
346			kfree_skb(skb);
347			return;
348		}
349
350		if (skb->sk != NULL)
351			skb_set_owner_w(skbn, skb->sk);
352
353		consume_skb(skb);
354		skb = skbn;
355	}
356
357	ptr = skb_push(skb, headroom);
358
359	ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
360
361	ax25_queue_xmit(skb, ax25->ax25_dev->dev);
362}
363
364/*
365 *	A small shim to dev_queue_xmit to add the KISS control byte, and do
366 *	any packet forwarding in operation.
367 */
368void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev)
369{
370	unsigned char *ptr;
371
372	skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));
373
374	ptr  = skb_push(skb, 1);
375	*ptr = 0x00;			/* KISS */
376
377	dev_queue_xmit(skb);
378}
379
380int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
381{
382	if (ax25->vs == nr) {
383		ax25_frames_acked(ax25, nr);
384		ax25_calculate_rtt(ax25);
385		ax25_stop_t1timer(ax25);
386		ax25_start_t3timer(ax25);
387		return 1;
388	} else {
389		if (ax25->va != nr) {
390			ax25_frames_acked(ax25, nr);
391			ax25_calculate_t1(ax25);
392			ax25_start_t1timer(ax25);
393			return 1;
394		}
395	}
396	return 0;
397}
398
399