1 /*
2 * X.25 Packet Layer release 002
3 *
4 * This is ALPHA test software. This code may break your machine,
5 * randomly fail to work with new releases, misbehave and/or generally
6 * screw up. It might even work.
7 *
8 * This code REQUIRES 2.1.15 or higher
9 *
10 * This module:
11 * This module is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 *
16 * History
17 * X.25 001 Jonathan Naylor Started coding.
18 * X.25 002 Jonathan Naylor Centralised disconnection code.
19 * New timer architecture.
20 * 2000-03-20 Daniela Squassoni Disabling/enabling of facilities
21 * negotiation.
22 * 2000-11-10 Henner Eisen Check and reset for out-of-sequence
23 * i-frames.
24 */
25
26 #include <linux/slab.h>
27 #include <linux/errno.h>
28 #include <linux/kernel.h>
29 #include <linux/string.h>
30 #include <linux/skbuff.h>
31 #include <net/sock.h>
32 #include <net/tcp_states.h>
33 #include <net/x25.h>
34
x25_queue_rx_frame(struct sock * sk,struct sk_buff * skb,int more)35 static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
36 {
37 struct sk_buff *skbo, *skbn = skb;
38 struct x25_sock *x25 = x25_sk(sk);
39
40 if (more) {
41 x25->fraglen += skb->len;
42 skb_queue_tail(&x25->fragment_queue, skb);
43 skb_set_owner_r(skb, sk);
44 return 0;
45 }
46
47 if (!more && x25->fraglen > 0) { /* End of fragment */
48 int len = x25->fraglen + skb->len;
49
50 if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
51 kfree_skb(skb);
52 return 1;
53 }
54
55 skb_queue_tail(&x25->fragment_queue, skb);
56
57 skb_reset_transport_header(skbn);
58
59 skbo = skb_dequeue(&x25->fragment_queue);
60 skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
61 skbo->len);
62 kfree_skb(skbo);
63
64 while ((skbo =
65 skb_dequeue(&x25->fragment_queue)) != NULL) {
66 skb_pull(skbo, (x25->neighbour->extended) ?
67 X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
68 skb_copy_from_linear_data(skbo,
69 skb_put(skbn, skbo->len),
70 skbo->len);
71 kfree_skb(skbo);
72 }
73
74 x25->fraglen = 0;
75 }
76
77 skb_set_owner_r(skbn, sk);
78 skb_queue_tail(&sk->sk_receive_queue, skbn);
79 if (!sock_flag(sk, SOCK_DEAD))
80 sk->sk_data_ready(sk, skbn->len);
81
82 return 0;
83 }
84
85 /*
86 * State machine for state 1, Awaiting Call Accepted State.
87 * The handling of the timer(s) is in file x25_timer.c.
88 * Handling of state 0 and connection release is in af_x25.c.
89 */
x25_state1_machine(struct sock * sk,struct sk_buff * skb,int frametype)90 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
91 {
92 struct x25_address source_addr, dest_addr;
93 int len;
94 struct x25_sock *x25 = x25_sk(sk);
95
96 switch (frametype) {
97 case X25_CALL_ACCEPTED: {
98
99 x25_stop_timer(sk);
100 x25->condition = 0x00;
101 x25->vs = 0;
102 x25->va = 0;
103 x25->vr = 0;
104 x25->vl = 0;
105 x25->state = X25_STATE_3;
106 sk->sk_state = TCP_ESTABLISHED;
107 /*
108 * Parse the data in the frame.
109 */
110 skb_pull(skb, X25_STD_MIN_LEN);
111
112 len = x25_parse_address_block(skb, &source_addr,
113 &dest_addr);
114 if (len > 0)
115 skb_pull(skb, len);
116 else if (len < 0)
117 goto out_clear;
118
119 len = x25_parse_facilities(skb, &x25->facilities,
120 &x25->dte_facilities,
121 &x25->vc_facil_mask);
122 if (len > 0)
123 skb_pull(skb, len);
124 else if (len < 0)
125 goto out_clear;
126 /*
127 * Copy any Call User Data.
128 */
129 if (skb->len > 0) {
130 skb_copy_from_linear_data(skb,
131 x25->calluserdata.cuddata,
132 skb->len);
133 x25->calluserdata.cudlength = skb->len;
134 }
135 if (!sock_flag(sk, SOCK_DEAD))
136 sk->sk_state_change(sk);
137 break;
138 }
139 case X25_CLEAR_REQUEST:
140 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
141 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
142 break;
143
144 default:
145 break;
146 }
147
148 return 0;
149
150 out_clear:
151 x25_write_internal(sk, X25_CLEAR_REQUEST);
152 x25->state = X25_STATE_2;
153 x25_start_t23timer(sk);
154 return 0;
155 }
156
157 /*
158 * State machine for state 2, Awaiting Clear Confirmation State.
159 * The handling of the timer(s) is in file x25_timer.c
160 * Handling of state 0 and connection release is in af_x25.c.
161 */
x25_state2_machine(struct sock * sk,struct sk_buff * skb,int frametype)162 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
163 {
164 switch (frametype) {
165
166 case X25_CLEAR_REQUEST:
167 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
168 x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
169 break;
170
171 case X25_CLEAR_CONFIRMATION:
172 x25_disconnect(sk, 0, 0, 0);
173 break;
174
175 default:
176 break;
177 }
178
179 return 0;
180 }
181
182 /*
183 * State machine for state 3, Connected State.
184 * The handling of the timer(s) is in file x25_timer.c
185 * Handling of state 0 and connection release is in af_x25.c.
186 */
x25_state3_machine(struct sock * sk,struct sk_buff * skb,int frametype,int ns,int nr,int q,int d,int m)187 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
188 {
189 int queued = 0;
190 int modulus;
191 struct x25_sock *x25 = x25_sk(sk);
192
193 modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
194
195 switch (frametype) {
196
197 case X25_RESET_REQUEST:
198 x25_write_internal(sk, X25_RESET_CONFIRMATION);
199 x25_stop_timer(sk);
200 x25->condition = 0x00;
201 x25->vs = 0;
202 x25->vr = 0;
203 x25->va = 0;
204 x25->vl = 0;
205 x25_requeue_frames(sk);
206 break;
207
208 case X25_CLEAR_REQUEST:
209 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
210 x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
211 break;
212
213 case X25_RR:
214 case X25_RNR:
215 if (!x25_validate_nr(sk, nr)) {
216 x25_clear_queues(sk);
217 x25_write_internal(sk, X25_RESET_REQUEST);
218 x25_start_t22timer(sk);
219 x25->condition = 0x00;
220 x25->vs = 0;
221 x25->vr = 0;
222 x25->va = 0;
223 x25->vl = 0;
224 x25->state = X25_STATE_4;
225 } else {
226 x25_frames_acked(sk, nr);
227 if (frametype == X25_RNR) {
228 x25->condition |= X25_COND_PEER_RX_BUSY;
229 } else {
230 x25->condition &= ~X25_COND_PEER_RX_BUSY;
231 }
232 }
233 break;
234
235 case X25_DATA: /* XXX */
236 x25->condition &= ~X25_COND_PEER_RX_BUSY;
237 if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
238 x25_clear_queues(sk);
239 x25_write_internal(sk, X25_RESET_REQUEST);
240 x25_start_t22timer(sk);
241 x25->condition = 0x00;
242 x25->vs = 0;
243 x25->vr = 0;
244 x25->va = 0;
245 x25->vl = 0;
246 x25->state = X25_STATE_4;
247 break;
248 }
249 x25_frames_acked(sk, nr);
250 if (ns == x25->vr) {
251 if (x25_queue_rx_frame(sk, skb, m) == 0) {
252 x25->vr = (x25->vr + 1) % modulus;
253 queued = 1;
254 } else {
255 /* Should never happen */
256 x25_clear_queues(sk);
257 x25_write_internal(sk, X25_RESET_REQUEST);
258 x25_start_t22timer(sk);
259 x25->condition = 0x00;
260 x25->vs = 0;
261 x25->vr = 0;
262 x25->va = 0;
263 x25->vl = 0;
264 x25->state = X25_STATE_4;
265 break;
266 }
267 if (atomic_read(&sk->sk_rmem_alloc) >
268 (sk->sk_rcvbuf >> 1))
269 x25->condition |= X25_COND_OWN_RX_BUSY;
270 }
271 /*
272 * If the window is full Ack it immediately, else
273 * start the holdback timer.
274 */
275 if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
276 x25->condition &= ~X25_COND_ACK_PENDING;
277 x25_stop_timer(sk);
278 x25_enquiry_response(sk);
279 } else {
280 x25->condition |= X25_COND_ACK_PENDING;
281 x25_start_t2timer(sk);
282 }
283 break;
284
285 case X25_INTERRUPT_CONFIRMATION:
286 clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
287 break;
288
289 case X25_INTERRUPT:
290 if (sock_flag(sk, SOCK_URGINLINE))
291 queued = !sock_queue_rcv_skb(sk, skb);
292 else {
293 skb_set_owner_r(skb, sk);
294 skb_queue_tail(&x25->interrupt_in_queue, skb);
295 queued = 1;
296 }
297 sk_send_sigurg(sk);
298 x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
299 break;
300
301 default:
302 printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
303 break;
304 }
305
306 return queued;
307 }
308
309 /*
310 * State machine for state 4, Awaiting Reset Confirmation State.
311 * The handling of the timer(s) is in file x25_timer.c
312 * Handling of state 0 and connection release is in af_x25.c.
313 */
x25_state4_machine(struct sock * sk,struct sk_buff * skb,int frametype)314 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
315 {
316 switch (frametype) {
317
318 case X25_RESET_REQUEST:
319 x25_write_internal(sk, X25_RESET_CONFIRMATION);
320 case X25_RESET_CONFIRMATION: {
321 struct x25_sock *x25 = x25_sk(sk);
322
323 x25_stop_timer(sk);
324 x25->condition = 0x00;
325 x25->va = 0;
326 x25->vr = 0;
327 x25->vs = 0;
328 x25->vl = 0;
329 x25->state = X25_STATE_3;
330 x25_requeue_frames(sk);
331 break;
332 }
333 case X25_CLEAR_REQUEST:
334 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
335 x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
336 break;
337
338 default:
339 break;
340 }
341
342 return 0;
343 }
344
345 /* Higher level upcall for a LAPB frame */
x25_process_rx_frame(struct sock * sk,struct sk_buff * skb)346 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
347 {
348 struct x25_sock *x25 = x25_sk(sk);
349 int queued = 0, frametype, ns, nr, q, d, m;
350
351 if (x25->state == X25_STATE_0)
352 return 0;
353
354 frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
355
356 switch (x25->state) {
357 case X25_STATE_1:
358 queued = x25_state1_machine(sk, skb, frametype);
359 break;
360 case X25_STATE_2:
361 queued = x25_state2_machine(sk, skb, frametype);
362 break;
363 case X25_STATE_3:
364 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
365 break;
366 case X25_STATE_4:
367 queued = x25_state4_machine(sk, skb, frametype);
368 break;
369 }
370
371 x25_kick(sk);
372
373 return queued;
374 }
375
x25_backlog_rcv(struct sock * sk,struct sk_buff * skb)376 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
377 {
378 int queued = x25_process_rx_frame(sk, skb);
379
380 if (!queued)
381 kfree_skb(skb);
382
383 return 0;
384 }
385