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/errno.h>
27 #include <linux/kernel.h>
28 #include <linux/string.h>
29 #include <linux/skbuff.h>
30 #include <net/sock.h>
31 #include <net/tcp_states.h>
32 #include <net/x25.h>
33
34 static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
35 {
36 struct sk_buff *skbo, *skbn = skb;
37 struct x25_sock *x25 = x25_sk(sk);
38
39 if (more) {
40 x25->fraglen += skb->len;
41 skb_queue_tail(&x25->fragment_queue, skb);
42 skb_set_owner_r(skb, sk);
43 return 0;
44 }
45
46 if (!more && x25->fraglen > 0) { /* End of fragment */
47 int len = x25->fraglen + skb->len;
48
49 if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
50 kfree_skb(skb);
51 return 1;
52 }
53
54 skb_queue_tail(&x25->fragment_queue, skb);
55
56 skb_reset_transport_header(skbn);
57
58 skbo = skb_dequeue(&x25->fragment_queue);
59 skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
60 skbo->len);
61 kfree_skb(skbo);
62
63 while ((skbo =
64 skb_dequeue(&x25->fragment_queue)) != NULL) {
65 skb_pull(skbo, (x25->neighbour->extended) ?
66 X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
67 skb_copy_from_linear_data(skbo,
68 skb_put(skbn, skbo->len),
69 skbo->len);
70 kfree_skb(skbo);
71 }
72
73 x25->fraglen = 0;
74 }
75
76 skb_set_owner_r(skbn, sk);
77 skb_queue_tail(&sk->sk_receive_queue, skbn);
78 if (!sock_flag(sk, SOCK_DEAD))
79 sk->sk_data_ready(sk, skbn->len);
80
81 return 0;
82 }
83
84 /*
85 * State machine for state 1, Awaiting Call Accepted State.
86 * The handling of the timer(s) is in file x25_timer.c.
87 * Handling of state 0 and connection release is in af_x25.c.
88 */
89 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
90 {
91 struct x25_address source_addr, dest_addr;
92
93 switch (frametype) {
94 case X25_CALL_ACCEPTED: {
95 struct x25_sock *x25 = x25_sk(sk);
96
97 x25_stop_timer(sk);
98 x25->condition = 0x00;
99 x25->vs = 0;
100 x25->va = 0;
101 x25->vr = 0;
102 x25->vl = 0;
103 x25->state = X25_STATE_3;
104 sk->sk_state = TCP_ESTABLISHED;
105 /*
106 * Parse the data in the frame.
107 */
108 skb_pull(skb, X25_STD_MIN_LEN);
109 skb_pull(skb, x25_addr_ntoa(skb->data, &source_addr, &dest_addr));
110 skb_pull(skb,
111 x25_parse_facilities(skb, &x25->facilities,
112 &x25->dte_facilities,
113 &x25->vc_facil_mask));
114 /*
115 * Copy any Call User Data.
116 */
117 if (skb->len >= 0) {
118 skb_copy_from_linear_data(skb,
119 x25->calluserdata.cuddata,
120 skb->len);
121 x25->calluserdata.cudlength = skb->len;
122 }
123 if (!sock_flag(sk, SOCK_DEAD))
124 sk->sk_state_change(sk);
125 break;
126 }
127 case X25_CLEAR_REQUEST:
128 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
129 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
130 break;
131
132 default:
133 break;
134 }
135
136 return 0;
137 }
138
139 /*
140 * State machine for state 2, Awaiting Clear Confirmation State.
141 * The handling of the timer(s) is in file x25_timer.c
142 * Handling of state 0 and connection release is in af_x25.c.
143 */
144 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
145 {
146 switch (frametype) {
147
148 case X25_CLEAR_REQUEST:
149 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
150 x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
151 break;
152
153 case X25_CLEAR_CONFIRMATION:
154 x25_disconnect(sk, 0, 0, 0);
155 break;
156
157 default:
158 break;
159 }
160
161 return 0;
162 }
163
164 /*
165 * State machine for state 3, Connected State.
166 * The handling of the timer(s) is in file x25_timer.c
167 * Handling of state 0 and connection release is in af_x25.c.
168 */
169 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
170 {
171 int queued = 0;
172 int modulus;
173 struct x25_sock *x25 = x25_sk(sk);
174
175 modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
176
177 switch (frametype) {
178
179 case X25_RESET_REQUEST:
180 x25_write_internal(sk, X25_RESET_CONFIRMATION);
181 x25_stop_timer(sk);
182 x25->condition = 0x00;
183 x25->vs = 0;
184 x25->vr = 0;
185 x25->va = 0;
186 x25->vl = 0;
187 x25_requeue_frames(sk);
188 break;
189
190 case X25_CLEAR_REQUEST:
191 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
192 x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
193 break;
194
195 case X25_RR:
196 case X25_RNR:
197 if (!x25_validate_nr(sk, nr)) {
198 x25_clear_queues(sk);
199 x25_write_internal(sk, X25_RESET_REQUEST);
200 x25_start_t22timer(sk);
201 x25->condition = 0x00;
202 x25->vs = 0;
203 x25->vr = 0;
204 x25->va = 0;
205 x25->vl = 0;
206 x25->state = X25_STATE_4;
207 } else {
208 x25_frames_acked(sk, nr);
209 if (frametype == X25_RNR) {
210 x25->condition |= X25_COND_PEER_RX_BUSY;
211 } else {
212 x25->condition &= ~X25_COND_PEER_RX_BUSY;
213 }
214 }
215 break;
216
217 case X25_DATA: /* XXX */
218 x25->condition &= ~X25_COND_PEER_RX_BUSY;
219 if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
220 x25_clear_queues(sk);
221 x25_write_internal(sk, X25_RESET_REQUEST);
222 x25_start_t22timer(sk);
223 x25->condition = 0x00;
224 x25->vs = 0;
225 x25->vr = 0;
226 x25->va = 0;
227 x25->vl = 0;
228 x25->state = X25_STATE_4;
229 break;
230 }
231 x25_frames_acked(sk, nr);
232 if (ns == x25->vr) {
233 if (x25_queue_rx_frame(sk, skb, m) == 0) {
234 x25->vr = (x25->vr + 1) % modulus;
235 queued = 1;
236 } else {
237 /* Should never happen */
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 if (atomic_read(&sk->sk_rmem_alloc) >
250 (sk->sk_rcvbuf >> 1))
251 x25->condition |= X25_COND_OWN_RX_BUSY;
252 }
253 /*
254 * If the window is full Ack it immediately, else
255 * start the holdback timer.
256 */
257 if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
258 x25->condition &= ~X25_COND_ACK_PENDING;
259 x25_stop_timer(sk);
260 x25_enquiry_response(sk);
261 } else {
262 x25->condition |= X25_COND_ACK_PENDING;
263 x25_start_t2timer(sk);
264 }
265 break;
266
267 case X25_INTERRUPT_CONFIRMATION:
268 x25->intflag = 0;
269 break;
270
271 case X25_INTERRUPT:
272 if (sock_flag(sk, SOCK_URGINLINE))
273 queued = !sock_queue_rcv_skb(sk, skb);
274 else {
275 skb_set_owner_r(skb, sk);
276 skb_queue_tail(&x25->interrupt_in_queue, skb);
277 queued = 1;
278 }
279 sk_send_sigurg(sk);
280 x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
281 break;
282
283 default:
284 printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
285 break;
286 }
287
288 return queued;
289 }
290
291 /*
292 * State machine for state 4, Awaiting Reset Confirmation State.
293 * The handling of the timer(s) is in file x25_timer.c
294 * Handling of state 0 and connection release is in af_x25.c.
295 */
296 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
297 {
298 switch (frametype) {
299
300 case X25_RESET_REQUEST:
301 x25_write_internal(sk, X25_RESET_CONFIRMATION);
302 case X25_RESET_CONFIRMATION: {
303 struct x25_sock *x25 = x25_sk(sk);
304
305 x25_stop_timer(sk);
306 x25->condition = 0x00;
307 x25->va = 0;
308 x25->vr = 0;
309 x25->vs = 0;
310 x25->vl = 0;
311 x25->state = X25_STATE_3;
312 x25_requeue_frames(sk);
313 break;
314 }
315 case X25_CLEAR_REQUEST:
316 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
317 x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
318 break;
319
320 default:
321 break;
322 }
323
324 return 0;
325 }
326
327 /* Higher level upcall for a LAPB frame */
328 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
329 {
330 struct x25_sock *x25 = x25_sk(sk);
331 int queued = 0, frametype, ns, nr, q, d, m;
332
333 if (x25->state == X25_STATE_0)
334 return 0;
335
336 frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
337
338 switch (x25->state) {
339 case X25_STATE_1:
340 queued = x25_state1_machine(sk, skb, frametype);
341 break;
342 case X25_STATE_2:
343 queued = x25_state2_machine(sk, skb, frametype);
344 break;
345 case X25_STATE_3:
346 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
347 break;
348 case X25_STATE_4:
349 queued = x25_state4_machine(sk, skb, frametype);
350 break;
351 }
352
353 x25_kick(sk);
354
355 return queued;
356 }
357
358 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
359 {
360 int queued = x25_process_rx_frame(sk, skb);
361
362 if (!queued)
363 kfree_skb(skb);
364
365 return 0;
366 }
367
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