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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 skbn->h.raw = skbn->data;
57
58 skbo = skb_dequeue(&x25->fragment_queue);
59 memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
60 kfree_skb(skbo);
61
62 while ((skbo =
63 skb_dequeue(&x25->fragment_queue)) != NULL) {
64 skb_pull(skbo, (x25->neighbour->extended) ?
65 X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
66 memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
67 kfree_skb(skbo);
68 }
69
70 x25->fraglen = 0;
71 }
72
73 skb_set_owner_r(skbn, sk);
74 skb_queue_tail(&sk->sk_receive_queue, skbn);
75 if (!sock_flag(sk, SOCK_DEAD))
76 sk->sk_data_ready(sk, skbn->len);
77
78 return 0;
79 }
80
81 /*
82 * State machine for state 1, Awaiting Call Accepted State.
83 * The handling of the timer(s) is in file x25_timer.c.
84 * Handling of state 0 and connection release is in af_x25.c.
85 */
86 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
87 {
88 struct x25_address source_addr, dest_addr;
89
90 switch (frametype) {
91 case X25_CALL_ACCEPTED: {
92 struct x25_sock *x25 = x25_sk(sk);
93
94 x25_stop_timer(sk);
95 x25->condition = 0x00;
96 x25->vs = 0;
97 x25->va = 0;
98 x25->vr = 0;
99 x25->vl = 0;
100 x25->state = X25_STATE_3;
101 sk->sk_state = TCP_ESTABLISHED;
102 /*
103 * Parse the data in the frame.
104 */
105 skb_pull(skb, X25_STD_MIN_LEN);
106 skb_pull(skb, x25_addr_ntoa(skb->data, &source_addr, &dest_addr));
107 skb_pull(skb,
108 x25_parse_facilities(skb, &x25->facilities,
109 &x25->dte_facilities,
110 &x25->vc_facil_mask));
111 /*
112 * Copy any Call User Data.
113 */
114 if (skb->len >= 0) {
115 memcpy(x25->calluserdata.cuddata, skb->data,
116 skb->len);
117 x25->calluserdata.cudlength = skb->len;
118 }
119 if (!sock_flag(sk, SOCK_DEAD))
120 sk->sk_state_change(sk);
121 break;
122 }
123 case X25_CLEAR_REQUEST:
124 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
125 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
126 break;
127
128 default:
129 break;
130 }
131
132 return 0;
133 }
134
135 /*
136 * State machine for state 2, Awaiting Clear Confirmation State.
137 * The handling of the timer(s) is in file x25_timer.c
138 * Handling of state 0 and connection release is in af_x25.c.
139 */
140 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
141 {
142 switch (frametype) {
143
144 case X25_CLEAR_REQUEST:
145 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
146 x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
147 break;
148
149 case X25_CLEAR_CONFIRMATION:
150 x25_disconnect(sk, 0, 0, 0);
151 break;
152
153 default:
154 break;
155 }
156
157 return 0;
158 }
159
160 /*
161 * State machine for state 3, Connected State.
162 * The handling of the timer(s) is in file x25_timer.c
163 * Handling of state 0 and connection release is in af_x25.c.
164 */
165 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
166 {
167 int queued = 0;
168 int modulus;
169 struct x25_sock *x25 = x25_sk(sk);
170
171 modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
172
173 switch (frametype) {
174
175 case X25_RESET_REQUEST:
176 x25_write_internal(sk, X25_RESET_CONFIRMATION);
177 x25_stop_timer(sk);
178 x25->condition = 0x00;
179 x25->vs = 0;
180 x25->vr = 0;
181 x25->va = 0;
182 x25->vl = 0;
183 x25_requeue_frames(sk);
184 break;
185
186 case X25_CLEAR_REQUEST:
187 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
188 x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
189 break;
190
191 case X25_RR:
192 case X25_RNR:
193 if (!x25_validate_nr(sk, nr)) {
194 x25_clear_queues(sk);
195 x25_write_internal(sk, X25_RESET_REQUEST);
196 x25_start_t22timer(sk);
197 x25->condition = 0x00;
198 x25->vs = 0;
199 x25->vr = 0;
200 x25->va = 0;
201 x25->vl = 0;
202 x25->state = X25_STATE_4;
203 } else {
204 x25_frames_acked(sk, nr);
205 if (frametype == X25_RNR) {
206 x25->condition |= X25_COND_PEER_RX_BUSY;
207 } else {
208 x25->condition &= ~X25_COND_PEER_RX_BUSY;
209 }
210 }
211 break;
212
213 case X25_DATA: /* XXX */
214 x25->condition &= ~X25_COND_PEER_RX_BUSY;
215 if ((ns != x25->vr) || !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 break;
226 }
227 x25_frames_acked(sk, nr);
228 if (ns == x25->vr) {
229 if (x25_queue_rx_frame(sk, skb, m) == 0) {
230 x25->vr = (x25->vr + 1) % modulus;
231 queued = 1;
232 } else {
233 /* Should never happen */
234 x25_clear_queues(sk);
235 x25_write_internal(sk, X25_RESET_REQUEST);
236 x25_start_t22timer(sk);
237 x25->condition = 0x00;
238 x25->vs = 0;
239 x25->vr = 0;
240 x25->va = 0;
241 x25->vl = 0;
242 x25->state = X25_STATE_4;
243 break;
244 }
245 if (atomic_read(&sk->sk_rmem_alloc) >
246 (sk->sk_rcvbuf / 2))
247 x25->condition |= X25_COND_OWN_RX_BUSY;
248 }
249 /*
250 * If the window is full Ack it immediately, else
251 * start the holdback timer.
252 */
253 if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
254 x25->condition &= ~X25_COND_ACK_PENDING;
255 x25_stop_timer(sk);
256 x25_enquiry_response(sk);
257 } else {
258 x25->condition |= X25_COND_ACK_PENDING;
259 x25_start_t2timer(sk);
260 }
261 break;
262
263 case X25_INTERRUPT_CONFIRMATION:
264 x25->intflag = 0;
265 break;
266
267 case X25_INTERRUPT:
268 if (sock_flag(sk, SOCK_URGINLINE))
269 queued = !sock_queue_rcv_skb(sk, skb);
270 else {
271 skb_set_owner_r(skb, sk);
272 skb_queue_tail(&x25->interrupt_in_queue, skb);
273 queued = 1;
274 }
275 sk_send_sigurg(sk);
276 x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
277 break;
278
279 default:
280 printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
281 break;
282 }
283
284 return queued;
285 }
286
287 /*
288 * State machine for state 4, Awaiting Reset Confirmation State.
289 * The handling of the timer(s) is in file x25_timer.c
290 * Handling of state 0 and connection release is in af_x25.c.
291 */
292 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
293 {
294 switch (frametype) {
295
296 case X25_RESET_REQUEST:
297 x25_write_internal(sk, X25_RESET_CONFIRMATION);
298 case X25_RESET_CONFIRMATION: {
299 struct x25_sock *x25 = x25_sk(sk);
300
301 x25_stop_timer(sk);
302 x25->condition = 0x00;
303 x25->va = 0;
304 x25->vr = 0;
305 x25->vs = 0;
306 x25->vl = 0;
307 x25->state = X25_STATE_3;
308 x25_requeue_frames(sk);
309 break;
310 }
311 case X25_CLEAR_REQUEST:
312 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
313 x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
314 break;
315
316 default:
317 break;
318 }
319
320 return 0;
321 }
322
323 /* Higher level upcall for a LAPB frame */
324 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
325 {
326 struct x25_sock *x25 = x25_sk(sk);
327 int queued = 0, frametype, ns, nr, q, d, m;
328
329 if (x25->state == X25_STATE_0)
330 return 0;
331
332 frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
333
334 switch (x25->state) {
335 case X25_STATE_1:
336 queued = x25_state1_machine(sk, skb, frametype);
337 break;
338 case X25_STATE_2:
339 queued = x25_state2_machine(sk, skb, frametype);
340 break;
341 case X25_STATE_3:
342 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
343 break;
344 case X25_STATE_4:
345 queued = x25_state4_machine(sk, skb, frametype);
346 break;
347 }
348
349 x25_kick(sk);
350
351 return queued;
352 }
353
354 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
355 {
356 int queued = x25_process_rx_frame(sk, skb);
357
358 if (!queued)
359 kfree_skb(skb);
360
361 return 0;
362 }
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