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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 * 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>
17#include <linux/timer.h>
18#include <linux/string.h>
19#include <linux/sockios.h>
20#include <linux/net.h>
21#include <linux/slab.h>
22#include <net/ax25.h>
23#include <linux/inet.h>
24#include <linux/netdevice.h>
25#include <linux/skbuff.h>
26#include <net/sock.h>
27#include <net/tcp_states.h>
28#include <asm/uaccess.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) {
58 skb = skb_dequeue(&ax25->ack_queue);
59 kfree_skb(skb);
60 ax25->va = (ax25->va + 1) % ax25->modulus;
61 }
62 }
63}
64
65void ax25_requeue_frames(ax25_cb *ax25)
66{
67 struct sk_buff *skb;
68
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_tail(&ax25->ack_queue)) != NULL)
75 skb_queue_head(&ax25->write_queue, skb);
76}
77
78/*
79 * Validate that the value of nr is between va and vs. Return true or
80 * false for testing.
81 */
82int ax25_validate_nr(ax25_cb *ax25, unsigned short nr)
83{
84 unsigned short vc = ax25->va;
85
86 while (vc != ax25->vs) {
87 if (nr == vc) return 1;
88 vc = (vc + 1) % ax25->modulus;
89 }
90
91 if (nr == ax25->vs) return 1;
92
93 return 0;
94}
95
96/*
97 * This routine is the centralised routine for parsing the control
98 * information for the different frame formats.
99 */
100int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf)
101{
102 unsigned char *frame;
103 int frametype = AX25_ILLEGAL;
104
105 frame = skb->data;
106 *ns = *nr = *pf = 0;
107
108 if (ax25->modulus == AX25_MODULUS) {
109 if ((frame[0] & AX25_S) == 0) {
110 frametype = AX25_I; /* I frame - carries NR/NS/PF */
111 *ns = (frame[0] >> 1) & 0x07;
112 *nr = (frame[0] >> 5) & 0x07;
113 *pf = frame[0] & AX25_PF;
114 } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
115 frametype = frame[0] & 0x0F;
116 *nr = (frame[0] >> 5) & 0x07;
117 *pf = frame[0] & AX25_PF;
118 } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
119 frametype = frame[0] & ~AX25_PF;
120 *pf = frame[0] & AX25_PF;
121 }
122 skb_pull(skb, 1);
123 } else {
124 if ((frame[0] & AX25_S) == 0) {
125 frametype = AX25_I; /* I frame - carries NR/NS/PF */
126 *ns = (frame[0] >> 1) & 0x7F;
127 *nr = (frame[1] >> 1) & 0x7F;
128 *pf = frame[1] & AX25_EPF;
129 skb_pull(skb, 2);
130 } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
131 frametype = frame[0] & 0x0F;
132 *nr = (frame[1] >> 1) & 0x7F;
133 *pf = frame[1] & AX25_EPF;
134 skb_pull(skb, 2);
135 } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
136 frametype = frame[0] & ~AX25_PF;
137 *pf = frame[0] & AX25_PF;
138 skb_pull(skb, 1);
139 }
140 }
141
142 return frametype;
143}
144
145/*
146 * This routine is called when the HDLC layer internally generates a
147 * command or response for the remote machine ( eg. RR, UA etc. ).
148 * Only supervisory or unnumbered frames are processed.
149 */
150void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type)
151{
152 struct sk_buff *skb;
153 unsigned char *dptr;
154
155 if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL)
156 return;
157
158 skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len);
159
160 skb_reset_network_header(skb);
161
162 /* Assume a response - address structure for DTE */
163 if (ax25->modulus == AX25_MODULUS) {
164 dptr = skb_put(skb, 1);
165 *dptr = frametype;
166 *dptr |= (poll_bit) ? AX25_PF : 0;
167 if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */
168 *dptr |= (ax25->vr << 5);
169 } else {
170 if ((frametype & AX25_U) == AX25_U) {
171 dptr = skb_put(skb, 1);
172 *dptr = frametype;
173 *dptr |= (poll_bit) ? AX25_PF : 0;
174 } else {
175 dptr = skb_put(skb, 2);
176 dptr[0] = frametype;
177 dptr[1] = (ax25->vr << 1);
178 dptr[1] |= (poll_bit) ? AX25_EPF : 0;
179 }
180 }
181
182 ax25_transmit_buffer(ax25, skb, type);
183}
184
185/*
186 * Send a 'DM' to an unknown connection attempt, or an invalid caller.
187 *
188 * Note: src here is the sender, thus it's the target of the DM
189 */
190void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi)
191{
192 struct sk_buff *skb;
193 char *dptr;
194 ax25_digi retdigi;
195
196 if (dev == NULL)
197 return;
198
199 if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL)
200 return; /* Next SABM will get DM'd */
201
202 skb_reserve(skb, dev->hard_header_len);
203 skb_reset_network_header(skb);
204
205 ax25_digi_invert(digi, &retdigi);
206
207 dptr = skb_put(skb, 1);
208
209 *dptr = AX25_DM | AX25_PF;
210
211 /*
212 * Do the address ourselves
213 */
214 dptr = skb_push(skb, ax25_addr_size(digi));
215 dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS);
216
217 ax25_queue_xmit(skb, dev);
218}
219
220/*
221 * Exponential backoff for AX.25
222 */
223void ax25_calculate_t1(ax25_cb *ax25)
224{
225 int n, t = 2;
226
227 switch (ax25->backoff) {
228 case 0:
229 break;
230
231 case 1:
232 t += 2 * ax25->n2count;
233 break;
234
235 case 2:
236 for (n = 0; n < ax25->n2count; n++)
237 t *= 2;
238 if (t > 8) t = 8;
239 break;
240 }
241
242 ax25->t1 = t * ax25->rtt;
243}
244
245/*
246 * Calculate the Round Trip Time
247 */
248void ax25_calculate_rtt(ax25_cb *ax25)
249{
250 if (ax25->backoff == 0)
251 return;
252
253 if (ax25_t1timer_running(ax25) && ax25->n2count == 0)
254 ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10;
255
256 if (ax25->rtt < AX25_T1CLAMPLO)
257 ax25->rtt = AX25_T1CLAMPLO;
258
259 if (ax25->rtt > AX25_T1CLAMPHI)
260 ax25->rtt = AX25_T1CLAMPHI;
261}
262
263void ax25_disconnect(ax25_cb *ax25, int reason)
264{
265 ax25_clear_queues(ax25);
266
267 ax25_stop_t1timer(ax25);
268 ax25_stop_t2timer(ax25);
269 ax25_stop_t3timer(ax25);
270 ax25_stop_idletimer(ax25);
271
272 ax25->state = AX25_STATE_0;
273
274 ax25_link_failed(ax25, reason);
275
276 if (ax25->sk != NULL) {
277 local_bh_disable();
278 bh_lock_sock(ax25->sk);
279 ax25->sk->sk_state = TCP_CLOSE;
280 ax25->sk->sk_err = reason;
281 ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
282 if (!sock_flag(ax25->sk, SOCK_DEAD)) {
283 ax25->sk->sk_state_change(ax25->sk);
284 sock_set_flag(ax25->sk, SOCK_DEAD);
285 }
286 bh_unlock_sock(ax25->sk);
287 local_bh_enable();
288 }
289}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *
4 * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
5 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
6 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
7 * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
8 */
9#include <linux/errno.h>
10#include <linux/types.h>
11#include <linux/socket.h>
12#include <linux/in.h>
13#include <linux/kernel.h>
14#include <linux/timer.h>
15#include <linux/string.h>
16#include <linux/sockios.h>
17#include <linux/net.h>
18#include <linux/slab.h>
19#include <net/ax25.h>
20#include <linux/inet.h>
21#include <linux/netdevice.h>
22#include <linux/skbuff.h>
23#include <net/sock.h>
24#include <net/tcp_states.h>
25#include <linux/uaccess.h>
26#include <linux/fcntl.h>
27#include <linux/mm.h>
28#include <linux/interrupt.h>
29
30/*
31 * This routine purges all the queues of frames.
32 */
33void ax25_clear_queues(ax25_cb *ax25)
34{
35 skb_queue_purge(&ax25->write_queue);
36 skb_queue_purge(&ax25->ack_queue);
37 skb_queue_purge(&ax25->reseq_queue);
38 skb_queue_purge(&ax25->frag_queue);
39}
40
41/*
42 * This routine purges the input queue of those frames that have been
43 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
44 * SDL diagram.
45 */
46void ax25_frames_acked(ax25_cb *ax25, unsigned short nr)
47{
48 struct sk_buff *skb;
49
50 /*
51 * Remove all the ack-ed frames from the ack queue.
52 */
53 if (ax25->va != nr) {
54 while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) {
55 skb = skb_dequeue(&ax25->ack_queue);
56 kfree_skb(skb);
57 ax25->va = (ax25->va + 1) % ax25->modulus;
58 }
59 }
60}
61
62void ax25_requeue_frames(ax25_cb *ax25)
63{
64 struct sk_buff *skb;
65
66 /*
67 * Requeue all the un-ack-ed frames on the output queue to be picked
68 * up by ax25_kick called from the timer. This arrangement handles the
69 * possibility of an empty output queue.
70 */
71 while ((skb = skb_dequeue_tail(&ax25->ack_queue)) != NULL)
72 skb_queue_head(&ax25->write_queue, skb);
73}
74
75/*
76 * Validate that the value of nr is between va and vs. Return true or
77 * false for testing.
78 */
79int ax25_validate_nr(ax25_cb *ax25, unsigned short nr)
80{
81 unsigned short vc = ax25->va;
82
83 while (vc != ax25->vs) {
84 if (nr == vc) return 1;
85 vc = (vc + 1) % ax25->modulus;
86 }
87
88 if (nr == ax25->vs) return 1;
89
90 return 0;
91}
92
93/*
94 * This routine is the centralised routine for parsing the control
95 * information for the different frame formats.
96 */
97int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf)
98{
99 unsigned char *frame;
100 int frametype = AX25_ILLEGAL;
101
102 frame = skb->data;
103 *ns = *nr = *pf = 0;
104
105 if (ax25->modulus == AX25_MODULUS) {
106 if ((frame[0] & AX25_S) == 0) {
107 frametype = AX25_I; /* I frame - carries NR/NS/PF */
108 *ns = (frame[0] >> 1) & 0x07;
109 *nr = (frame[0] >> 5) & 0x07;
110 *pf = frame[0] & AX25_PF;
111 } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
112 frametype = frame[0] & 0x0F;
113 *nr = (frame[0] >> 5) & 0x07;
114 *pf = frame[0] & AX25_PF;
115 } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
116 frametype = frame[0] & ~AX25_PF;
117 *pf = frame[0] & AX25_PF;
118 }
119 skb_pull(skb, 1);
120 } else {
121 if ((frame[0] & AX25_S) == 0) {
122 frametype = AX25_I; /* I frame - carries NR/NS/PF */
123 *ns = (frame[0] >> 1) & 0x7F;
124 *nr = (frame[1] >> 1) & 0x7F;
125 *pf = frame[1] & AX25_EPF;
126 skb_pull(skb, 2);
127 } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
128 frametype = frame[0] & 0x0F;
129 *nr = (frame[1] >> 1) & 0x7F;
130 *pf = frame[1] & AX25_EPF;
131 skb_pull(skb, 2);
132 } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
133 frametype = frame[0] & ~AX25_PF;
134 *pf = frame[0] & AX25_PF;
135 skb_pull(skb, 1);
136 }
137 }
138
139 return frametype;
140}
141
142/*
143 * This routine is called when the HDLC layer internally generates a
144 * command or response for the remote machine ( eg. RR, UA etc. ).
145 * Only supervisory or unnumbered frames are processed.
146 */
147void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type)
148{
149 struct sk_buff *skb;
150 unsigned char *dptr;
151
152 if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL)
153 return;
154
155 skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len);
156
157 skb_reset_network_header(skb);
158
159 /* Assume a response - address structure for DTE */
160 if (ax25->modulus == AX25_MODULUS) {
161 dptr = skb_put(skb, 1);
162 *dptr = frametype;
163 *dptr |= (poll_bit) ? AX25_PF : 0;
164 if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */
165 *dptr |= (ax25->vr << 5);
166 } else {
167 if ((frametype & AX25_U) == AX25_U) {
168 dptr = skb_put(skb, 1);
169 *dptr = frametype;
170 *dptr |= (poll_bit) ? AX25_PF : 0;
171 } else {
172 dptr = skb_put(skb, 2);
173 dptr[0] = frametype;
174 dptr[1] = (ax25->vr << 1);
175 dptr[1] |= (poll_bit) ? AX25_EPF : 0;
176 }
177 }
178
179 ax25_transmit_buffer(ax25, skb, type);
180}
181
182/*
183 * Send a 'DM' to an unknown connection attempt, or an invalid caller.
184 *
185 * Note: src here is the sender, thus it's the target of the DM
186 */
187void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi)
188{
189 struct sk_buff *skb;
190 char *dptr;
191 ax25_digi retdigi;
192
193 if (dev == NULL)
194 return;
195
196 if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL)
197 return; /* Next SABM will get DM'd */
198
199 skb_reserve(skb, dev->hard_header_len);
200 skb_reset_network_header(skb);
201
202 ax25_digi_invert(digi, &retdigi);
203
204 dptr = skb_put(skb, 1);
205
206 *dptr = AX25_DM | AX25_PF;
207
208 /*
209 * Do the address ourselves
210 */
211 dptr = skb_push(skb, ax25_addr_size(digi));
212 dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS);
213
214 ax25_queue_xmit(skb, dev);
215}
216
217/*
218 * Exponential backoff for AX.25
219 */
220void ax25_calculate_t1(ax25_cb *ax25)
221{
222 int n, t = 2;
223
224 switch (ax25->backoff) {
225 case 0:
226 break;
227
228 case 1:
229 t += 2 * ax25->n2count;
230 break;
231
232 case 2:
233 for (n = 0; n < ax25->n2count; n++)
234 t *= 2;
235 if (t > 8) t = 8;
236 break;
237 }
238
239 ax25->t1 = t * ax25->rtt;
240}
241
242/*
243 * Calculate the Round Trip Time
244 */
245void ax25_calculate_rtt(ax25_cb *ax25)
246{
247 if (ax25->backoff == 0)
248 return;
249
250 if (ax25_t1timer_running(ax25) && ax25->n2count == 0)
251 ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10;
252
253 if (ax25->rtt < AX25_T1CLAMPLO)
254 ax25->rtt = AX25_T1CLAMPLO;
255
256 if (ax25->rtt > AX25_T1CLAMPHI)
257 ax25->rtt = AX25_T1CLAMPHI;
258}
259
260void ax25_disconnect(ax25_cb *ax25, int reason)
261{
262 ax25_clear_queues(ax25);
263
264 if (reason == ENETUNREACH) {
265 del_timer_sync(&ax25->timer);
266 del_timer_sync(&ax25->t1timer);
267 del_timer_sync(&ax25->t2timer);
268 del_timer_sync(&ax25->t3timer);
269 del_timer_sync(&ax25->idletimer);
270 } else {
271 if (ax25->sk && !sock_flag(ax25->sk, SOCK_DESTROY))
272 ax25_stop_heartbeat(ax25);
273 ax25_stop_t1timer(ax25);
274 ax25_stop_t2timer(ax25);
275 ax25_stop_t3timer(ax25);
276 ax25_stop_idletimer(ax25);
277 }
278
279 ax25->state = AX25_STATE_0;
280
281 ax25_link_failed(ax25, reason);
282
283 if (ax25->sk != NULL) {
284 local_bh_disable();
285 bh_lock_sock(ax25->sk);
286 ax25->sk->sk_state = TCP_CLOSE;
287 ax25->sk->sk_err = reason;
288 ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
289 if (!sock_flag(ax25->sk, SOCK_DEAD)) {
290 ax25->sk->sk_state_change(ax25->sk);
291 sock_set_flag(ax25->sk, SOCK_DEAD);
292 }
293 bh_unlock_sock(ax25->sk);
294 local_bh_enable();
295 }
296}