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