1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 *
4 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
5 *
6 * Most of this code is based on the SDL diagrams published in the 7th ARRL
7 * Computer Networking Conference papers. The diagrams have mistakes in them,
8 * but are mostly correct. Before you modify the code could you read the SDL
9 * diagrams as the code is not obvious and probably very easy to break.
10 */
11 #include <linux/errno.h>
12 #include <linux/types.h>
13 #include <linux/socket.h>
14 #include <linux/in.h>
15 #include <linux/kernel.h>
16 #include <linux/timer.h>
17 #include <linux/string.h>
18 #include <linux/sockios.h>
19 #include <linux/net.h>
20 #include <net/ax25.h>
21 #include <linux/inet.h>
22 #include <linux/netdevice.h>
23 #include <linux/skbuff.h>
24 #include <net/sock.h>
25 #include <net/tcp_states.h>
26 #include <linux/fcntl.h>
27 #include <linux/mm.h>
28 #include <linux/interrupt.h>
29 #include <net/rose.h>
30
31 /*
32 * State machine for state 1, Awaiting Call Accepted State.
33 * The handling of the timer(s) is in file rose_timer.c.
34 * Handling of state 0 and connection release is in af_rose.c.
35 */
rose_state1_machine(struct sock * sk,struct sk_buff * skb,int frametype)36 static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
37 {
38 struct rose_sock *rose = rose_sk(sk);
39
40 switch (frametype) {
41 case ROSE_CALL_ACCEPTED:
42 rose_stop_timer(sk);
43 rose_start_idletimer(sk);
44 rose->condition = 0x00;
45 rose->vs = 0;
46 rose->va = 0;
47 rose->vr = 0;
48 rose->vl = 0;
49 rose->state = ROSE_STATE_3;
50 sk->sk_state = TCP_ESTABLISHED;
51 if (!sock_flag(sk, SOCK_DEAD))
52 sk->sk_state_change(sk);
53 break;
54
55 case ROSE_CLEAR_REQUEST:
56 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
57 rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
58 rose->neighbour->use--;
59 break;
60
61 default:
62 break;
63 }
64
65 return 0;
66 }
67
68 /*
69 * State machine for state 2, Awaiting Clear Confirmation State.
70 * The handling of the timer(s) is in file rose_timer.c
71 * Handling of state 0 and connection release is in af_rose.c.
72 */
rose_state2_machine(struct sock * sk,struct sk_buff * skb,int frametype)73 static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
74 {
75 struct rose_sock *rose = rose_sk(sk);
76
77 switch (frametype) {
78 case ROSE_CLEAR_REQUEST:
79 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
80 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
81 rose->neighbour->use--;
82 break;
83
84 case ROSE_CLEAR_CONFIRMATION:
85 rose_disconnect(sk, 0, -1, -1);
86 rose->neighbour->use--;
87 break;
88
89 default:
90 break;
91 }
92
93 return 0;
94 }
95
96 /*
97 * State machine for state 3, Connected State.
98 * The handling of the timer(s) is in file rose_timer.c
99 * Handling of state 0 and connection release is in af_rose.c.
100 */
rose_state3_machine(struct sock * sk,struct sk_buff * skb,int frametype,int ns,int nr,int q,int d,int m)101 static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
102 {
103 struct rose_sock *rose = rose_sk(sk);
104 int queued = 0;
105
106 switch (frametype) {
107 case ROSE_RESET_REQUEST:
108 rose_stop_timer(sk);
109 rose_start_idletimer(sk);
110 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
111 rose->condition = 0x00;
112 rose->vs = 0;
113 rose->vr = 0;
114 rose->va = 0;
115 rose->vl = 0;
116 rose_requeue_frames(sk);
117 break;
118
119 case ROSE_CLEAR_REQUEST:
120 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
121 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
122 rose->neighbour->use--;
123 break;
124
125 case ROSE_RR:
126 case ROSE_RNR:
127 if (!rose_validate_nr(sk, nr)) {
128 rose_write_internal(sk, ROSE_RESET_REQUEST);
129 rose->condition = 0x00;
130 rose->vs = 0;
131 rose->vr = 0;
132 rose->va = 0;
133 rose->vl = 0;
134 rose->state = ROSE_STATE_4;
135 rose_start_t2timer(sk);
136 rose_stop_idletimer(sk);
137 } else {
138 rose_frames_acked(sk, nr);
139 if (frametype == ROSE_RNR) {
140 rose->condition |= ROSE_COND_PEER_RX_BUSY;
141 } else {
142 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
143 }
144 }
145 break;
146
147 case ROSE_DATA: /* XXX */
148 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
149 if (!rose_validate_nr(sk, nr)) {
150 rose_write_internal(sk, ROSE_RESET_REQUEST);
151 rose->condition = 0x00;
152 rose->vs = 0;
153 rose->vr = 0;
154 rose->va = 0;
155 rose->vl = 0;
156 rose->state = ROSE_STATE_4;
157 rose_start_t2timer(sk);
158 rose_stop_idletimer(sk);
159 break;
160 }
161 rose_frames_acked(sk, nr);
162 if (ns == rose->vr) {
163 rose_start_idletimer(sk);
164 if (sk_filter_trim_cap(sk, skb, ROSE_MIN_LEN) == 0 &&
165 __sock_queue_rcv_skb(sk, skb) == 0) {
166 rose->vr = (rose->vr + 1) % ROSE_MODULUS;
167 queued = 1;
168 } else {
169 /* Should never happen ! */
170 rose_write_internal(sk, ROSE_RESET_REQUEST);
171 rose->condition = 0x00;
172 rose->vs = 0;
173 rose->vr = 0;
174 rose->va = 0;
175 rose->vl = 0;
176 rose->state = ROSE_STATE_4;
177 rose_start_t2timer(sk);
178 rose_stop_idletimer(sk);
179 break;
180 }
181 if (atomic_read(&sk->sk_rmem_alloc) >
182 (sk->sk_rcvbuf >> 1))
183 rose->condition |= ROSE_COND_OWN_RX_BUSY;
184 }
185 /*
186 * If the window is full, ack the frame, else start the
187 * acknowledge hold back timer.
188 */
189 if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
190 rose->condition &= ~ROSE_COND_ACK_PENDING;
191 rose_stop_timer(sk);
192 rose_enquiry_response(sk);
193 } else {
194 rose->condition |= ROSE_COND_ACK_PENDING;
195 rose_start_hbtimer(sk);
196 }
197 break;
198
199 default:
200 printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
201 break;
202 }
203
204 return queued;
205 }
206
207 /*
208 * State machine for state 4, Awaiting Reset Confirmation State.
209 * The handling of the timer(s) is in file rose_timer.c
210 * Handling of state 0 and connection release is in af_rose.c.
211 */
rose_state4_machine(struct sock * sk,struct sk_buff * skb,int frametype)212 static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
213 {
214 struct rose_sock *rose = rose_sk(sk);
215
216 switch (frametype) {
217 case ROSE_RESET_REQUEST:
218 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
219 fallthrough;
220 case ROSE_RESET_CONFIRMATION:
221 rose_stop_timer(sk);
222 rose_start_idletimer(sk);
223 rose->condition = 0x00;
224 rose->va = 0;
225 rose->vr = 0;
226 rose->vs = 0;
227 rose->vl = 0;
228 rose->state = ROSE_STATE_3;
229 rose_requeue_frames(sk);
230 break;
231
232 case ROSE_CLEAR_REQUEST:
233 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
234 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
235 rose->neighbour->use--;
236 break;
237
238 default:
239 break;
240 }
241
242 return 0;
243 }
244
245 /*
246 * State machine for state 5, Awaiting Call Acceptance State.
247 * The handling of the timer(s) is in file rose_timer.c
248 * Handling of state 0 and connection release is in af_rose.c.
249 */
rose_state5_machine(struct sock * sk,struct sk_buff * skb,int frametype)250 static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
251 {
252 if (frametype == ROSE_CLEAR_REQUEST) {
253 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
254 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
255 rose_sk(sk)->neighbour->use--;
256 }
257
258 return 0;
259 }
260
261 /* Higher level upcall for a LAPB frame */
rose_process_rx_frame(struct sock * sk,struct sk_buff * skb)262 int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
263 {
264 struct rose_sock *rose = rose_sk(sk);
265 int queued = 0, frametype, ns, nr, q, d, m;
266
267 if (rose->state == ROSE_STATE_0)
268 return 0;
269
270 frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);
271
272 switch (rose->state) {
273 case ROSE_STATE_1:
274 queued = rose_state1_machine(sk, skb, frametype);
275 break;
276 case ROSE_STATE_2:
277 queued = rose_state2_machine(sk, skb, frametype);
278 break;
279 case ROSE_STATE_3:
280 queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
281 break;
282 case ROSE_STATE_4:
283 queued = rose_state4_machine(sk, skb, frametype);
284 break;
285 case ROSE_STATE_5:
286 queued = rose_state5_machine(sk, skb, frametype);
287 break;
288 }
289
290 rose_kick(sk);
291
292 return queued;
293 }
294