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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
11 */
12#include <linux/errno.h>
13#include <linux/types.h>
14#include <linux/socket.h>
15#include <linux/in.h>
16#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/timer.h>
18#include <linux/string.h>
19#include <linux/sockios.h>
20#include <linux/net.h>
21#include <net/ax25.h>
22#include <linux/inet.h>
23#include <linux/netdevice.h>
24#include <linux/skbuff.h>
25#include <net/sock.h>
Arnaldo Carvalho de Meloc752f072005-08-09 20:08:28 -070026#include <net/tcp_states.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <asm/uaccess.h>
28#include <asm/system.h>
29#include <linux/fcntl.h>
30#include <linux/mm.h>
31#include <linux/interrupt.h>
32
33/*
34 * This routine purges all the queues of frames.
35 */
36void ax25_clear_queues(ax25_cb *ax25)
37{
38 skb_queue_purge(&ax25->write_queue);
39 skb_queue_purge(&ax25->ack_queue);
40 skb_queue_purge(&ax25->reseq_queue);
41 skb_queue_purge(&ax25->frag_queue);
42}
43
44/*
45 * This routine purges the input queue of those frames that have been
46 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
47 * SDL diagram.
48 */
49void ax25_frames_acked(ax25_cb *ax25, unsigned short nr)
50{
51 struct sk_buff *skb;
52
53 /*
54 * Remove all the ack-ed frames from the ack queue.
55 */
56 if (ax25->va != nr) {
57 while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) {
YOSHIFUJI Hideaki528930b2007-02-09 23:24:31 +090058 skb = skb_dequeue(&ax25->ack_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 kfree_skb(skb);
60 ax25->va = (ax25->va + 1) % ax25->modulus;
61 }
62 }
63}
64
65void ax25_requeue_frames(ax25_cb *ax25)
66{
YOSHIFUJI Hideaki528930b2007-02-09 23:24:31 +090067 struct sk_buff *skb, *skb_prev = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
69 /*
70 * Requeue all the un-ack-ed frames on the output queue to be picked
71 * up by ax25_kick called from the timer. This arrangement handles the
72 * possibility of an empty output queue.
73 */
74 while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) {
75 if (skb_prev == NULL)
76 skb_queue_head(&ax25->write_queue, skb);
77 else
David S. Miller8728b832005-08-09 19:25:21 -070078 skb_append(skb_prev, skb, &ax25->write_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 skb_prev = skb;
80 }
81}
82
83/*
84 * Validate that the value of nr is between va and vs. Return true or
85 * false for testing.
86 */
87int ax25_validate_nr(ax25_cb *ax25, unsigned short nr)
88{
89 unsigned short vc = ax25->va;
90
91 while (vc != ax25->vs) {
92 if (nr == vc) return 1;
93 vc = (vc + 1) % ax25->modulus;
94 }
95
96 if (nr == ax25->vs) return 1;
97
98 return 0;
99}
100
101/*
102 * This routine is the centralised routine for parsing the control
103 * information for the different frame formats.
104 */
105int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf)
106{
107 unsigned char *frame;
108 int frametype = AX25_ILLEGAL;
109
110 frame = skb->data;
111 *ns = *nr = *pf = 0;
112
113 if (ax25->modulus == AX25_MODULUS) {
114 if ((frame[0] & AX25_S) == 0) {
115 frametype = AX25_I; /* I frame - carries NR/NS/PF */
116 *ns = (frame[0] >> 1) & 0x07;
117 *nr = (frame[0] >> 5) & 0x07;
118 *pf = frame[0] & AX25_PF;
119 } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
120 frametype = frame[0] & 0x0F;
121 *nr = (frame[0] >> 5) & 0x07;
122 *pf = frame[0] & AX25_PF;
123 } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
124 frametype = frame[0] & ~AX25_PF;
125 *pf = frame[0] & AX25_PF;
126 }
127 skb_pull(skb, 1);
128 } else {
129 if ((frame[0] & AX25_S) == 0) {
130 frametype = AX25_I; /* I frame - carries NR/NS/PF */
131 *ns = (frame[0] >> 1) & 0x7F;
132 *nr = (frame[1] >> 1) & 0x7F;
133 *pf = frame[1] & AX25_EPF;
134 skb_pull(skb, 2);
135 } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
136 frametype = frame[0] & 0x0F;
137 *nr = (frame[1] >> 1) & 0x7F;
138 *pf = frame[1] & AX25_EPF;
139 skb_pull(skb, 2);
140 } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
141 frametype = frame[0] & ~AX25_PF;
142 *pf = frame[0] & AX25_PF;
143 skb_pull(skb, 1);
144 }
145 }
146
147 return frametype;
148}
149
150/*
151 * This routine is called when the HDLC layer internally generates a
152 * command or response for the remote machine ( eg. RR, UA etc. ).
153 * Only supervisory or unnumbered frames are processed.
154 */
155void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type)
156{
157 struct sk_buff *skb;
158 unsigned char *dptr;
159
160 if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL)
161 return;
162
163 skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len);
164
165 skb->nh.raw = skb->data;
166
167 /* Assume a response - address structure for DTE */
168 if (ax25->modulus == AX25_MODULUS) {
169 dptr = skb_put(skb, 1);
170 *dptr = frametype;
171 *dptr |= (poll_bit) ? AX25_PF : 0;
172 if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */
173 *dptr |= (ax25->vr << 5);
174 } else {
175 if ((frametype & AX25_U) == AX25_U) {
176 dptr = skb_put(skb, 1);
177 *dptr = frametype;
178 *dptr |= (poll_bit) ? AX25_PF : 0;
179 } else {
180 dptr = skb_put(skb, 2);
181 dptr[0] = frametype;
182 dptr[1] = (ax25->vr << 1);
183 dptr[1] |= (poll_bit) ? AX25_EPF : 0;
184 }
185 }
186
187 ax25_transmit_buffer(ax25, skb, type);
188}
189
190/*
191 * Send a 'DM' to an unknown connection attempt, or an invalid caller.
192 *
193 * Note: src here is the sender, thus it's the target of the DM
194 */
195void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi)
196{
197 struct sk_buff *skb;
198 char *dptr;
199 ax25_digi retdigi;
200
201 if (dev == NULL)
202 return;
203
204 if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL)
205 return; /* Next SABM will get DM'd */
206
207 skb_reserve(skb, dev->hard_header_len);
208 skb->nh.raw = skb->data;
209
210 ax25_digi_invert(digi, &retdigi);
211
212 dptr = skb_put(skb, 1);
213
214 *dptr = AX25_DM | AX25_PF;
215
216 /*
217 * Do the address ourselves
218 */
219 dptr = skb_push(skb, ax25_addr_size(digi));
220 dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS);
221
Arnaldo Carvalho de Melo29c4be52005-04-21 16:46:56 -0700222 ax25_queue_xmit(skb, dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223}
224
225/*
226 * Exponential backoff for AX.25
227 */
228void ax25_calculate_t1(ax25_cb *ax25)
229{
230 int n, t = 2;
231
232 switch (ax25->backoff) {
233 case 0:
234 break;
235
236 case 1:
237 t += 2 * ax25->n2count;
238 break;
239
240 case 2:
241 for (n = 0; n < ax25->n2count; n++)
242 t *= 2;
243 if (t > 8) t = 8;
244 break;
245 }
246
247 ax25->t1 = t * ax25->rtt;
248}
249
250/*
251 * Calculate the Round Trip Time
252 */
253void ax25_calculate_rtt(ax25_cb *ax25)
254{
255 if (ax25->backoff == 0)
256 return;
257
258 if (ax25_t1timer_running(ax25) && ax25->n2count == 0)
259 ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10;
260
261 if (ax25->rtt < AX25_T1CLAMPLO)
262 ax25->rtt = AX25_T1CLAMPLO;
263
264 if (ax25->rtt > AX25_T1CLAMPHI)
265 ax25->rtt = AX25_T1CLAMPHI;
266}
267
268void ax25_disconnect(ax25_cb *ax25, int reason)
269{
270 ax25_clear_queues(ax25);
271
272 ax25_stop_t1timer(ax25);
273 ax25_stop_t2timer(ax25);
274 ax25_stop_t3timer(ax25);
275 ax25_stop_idletimer(ax25);
276
277 ax25->state = AX25_STATE_0;
278
279 ax25_link_failed(ax25, reason);
280
281 if (ax25->sk != NULL) {
282 bh_lock_sock(ax25->sk);
283 ax25->sk->sk_state = TCP_CLOSE;
284 ax25->sk->sk_err = reason;
285 ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
286 if (!sock_flag(ax25->sk, SOCK_DEAD)) {
287 ax25->sk->sk_state_change(ax25->sk);
288 sock_set_flag(ax25->sk, SOCK_DEAD);
289 }
290 bh_unlock_sock(ax25->sk);
291 }
292}