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/filter.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 <net/ax25.h> |
22 | #include <linux/inet.h> |
23 | #include <linux/netdevice.h> |
24 | #include <linux/skbuff.h> |
25 | #include <net/sock.h> |
26 | #include <net/tcp_states.h> |
27 | #include <linux/fcntl.h> |
28 | #include <linux/mm.h> |
29 | #include <linux/interrupt.h> |
30 | #include <net/rose.h> |
31 | |
32 | /* |
33 | * State machine for state 1, Awaiting Call Accepted State. |
34 | * The handling of the timer(s) is in file rose_timer.c. |
35 | * Handling of state 0 and connection release is in af_rose.c. |
36 | */ |
37 | static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
38 | { |
39 | struct rose_sock *rose = rose_sk(sk); |
40 | |
41 | switch (frametype) { |
42 | case ROSE_CALL_ACCEPTED: |
43 | rose_stop_timer(sk); |
44 | rose_start_idletimer(sk); |
45 | rose->condition = 0x00; |
46 | rose->vs = 0; |
47 | rose->va = 0; |
48 | rose->vr = 0; |
49 | rose->vl = 0; |
50 | rose->state = ROSE_STATE_3; |
51 | sk->sk_state = TCP_ESTABLISHED; |
52 | if (!sock_flag(sk, flag: SOCK_DEAD)) |
53 | sk->sk_state_change(sk); |
54 | break; |
55 | |
56 | case ROSE_CLEAR_REQUEST: |
57 | rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); |
58 | rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); |
59 | rose->neighbour->use--; |
60 | break; |
61 | |
62 | default: |
63 | break; |
64 | } |
65 | |
66 | return 0; |
67 | } |
68 | |
69 | /* |
70 | * State machine for state 2, Awaiting Clear Confirmation State. |
71 | * The handling of the timer(s) is in file rose_timer.c |
72 | * Handling of state 0 and connection release is in af_rose.c. |
73 | */ |
74 | static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
75 | { |
76 | struct rose_sock *rose = rose_sk(sk); |
77 | |
78 | switch (frametype) { |
79 | case ROSE_CLEAR_REQUEST: |
80 | rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); |
81 | rose_disconnect(sk, 0, skb->data[3], skb->data[4]); |
82 | rose->neighbour->use--; |
83 | break; |
84 | |
85 | case ROSE_CLEAR_CONFIRMATION: |
86 | rose_disconnect(sk, 0, -1, -1); |
87 | rose->neighbour->use--; |
88 | break; |
89 | |
90 | default: |
91 | break; |
92 | } |
93 | |
94 | return 0; |
95 | } |
96 | |
97 | /* |
98 | * State machine for state 3, Connected State. |
99 | * The handling of the timer(s) is in file rose_timer.c |
100 | * Handling of state 0 and connection release is in af_rose.c. |
101 | */ |
102 | static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m) |
103 | { |
104 | struct rose_sock *rose = rose_sk(sk); |
105 | int queued = 0; |
106 | |
107 | switch (frametype) { |
108 | case ROSE_RESET_REQUEST: |
109 | rose_stop_timer(sk); |
110 | rose_start_idletimer(sk); |
111 | rose_write_internal(sk, ROSE_RESET_CONFIRMATION); |
112 | rose->condition = 0x00; |
113 | rose->vs = 0; |
114 | rose->vr = 0; |
115 | rose->va = 0; |
116 | rose->vl = 0; |
117 | rose_requeue_frames(sk); |
118 | break; |
119 | |
120 | case ROSE_CLEAR_REQUEST: |
121 | rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); |
122 | rose_disconnect(sk, 0, skb->data[3], skb->data[4]); |
123 | rose->neighbour->use--; |
124 | break; |
125 | |
126 | case ROSE_RR: |
127 | case ROSE_RNR: |
128 | if (!rose_validate_nr(sk, nr)) { |
129 | rose_write_internal(sk, ROSE_RESET_REQUEST); |
130 | rose->condition = 0x00; |
131 | rose->vs = 0; |
132 | rose->vr = 0; |
133 | rose->va = 0; |
134 | rose->vl = 0; |
135 | rose->state = ROSE_STATE_4; |
136 | rose_start_t2timer(sk); |
137 | rose_stop_idletimer(sk); |
138 | } else { |
139 | rose_frames_acked(sk, nr); |
140 | if (frametype == ROSE_RNR) { |
141 | rose->condition |= ROSE_COND_PEER_RX_BUSY; |
142 | } else { |
143 | rose->condition &= ~ROSE_COND_PEER_RX_BUSY; |
144 | } |
145 | } |
146 | break; |
147 | |
148 | case ROSE_DATA: /* XXX */ |
149 | rose->condition &= ~ROSE_COND_PEER_RX_BUSY; |
150 | if (!rose_validate_nr(sk, nr)) { |
151 | rose_write_internal(sk, ROSE_RESET_REQUEST); |
152 | rose->condition = 0x00; |
153 | rose->vs = 0; |
154 | rose->vr = 0; |
155 | rose->va = 0; |
156 | rose->vl = 0; |
157 | rose->state = ROSE_STATE_4; |
158 | rose_start_t2timer(sk); |
159 | rose_stop_idletimer(sk); |
160 | break; |
161 | } |
162 | rose_frames_acked(sk, nr); |
163 | if (ns == rose->vr) { |
164 | rose_start_idletimer(sk); |
165 | if (sk_filter_trim_cap(sk, skb, ROSE_MIN_LEN) == 0 && |
166 | __sock_queue_rcv_skb(sk, skb) == 0) { |
167 | rose->vr = (rose->vr + 1) % ROSE_MODULUS; |
168 | queued = 1; |
169 | } else { |
170 | /* Should never happen ! */ |
171 | rose_write_internal(sk, ROSE_RESET_REQUEST); |
172 | rose->condition = 0x00; |
173 | rose->vs = 0; |
174 | rose->vr = 0; |
175 | rose->va = 0; |
176 | rose->vl = 0; |
177 | rose->state = ROSE_STATE_4; |
178 | rose_start_t2timer(sk); |
179 | rose_stop_idletimer(sk); |
180 | break; |
181 | } |
182 | if (atomic_read(v: &sk->sk_rmem_alloc) > |
183 | (sk->sk_rcvbuf >> 1)) |
184 | rose->condition |= ROSE_COND_OWN_RX_BUSY; |
185 | } |
186 | /* |
187 | * If the window is full, ack the frame, else start the |
188 | * acknowledge hold back timer. |
189 | */ |
190 | if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) { |
191 | rose->condition &= ~ROSE_COND_ACK_PENDING; |
192 | rose_stop_timer(sk); |
193 | rose_enquiry_response(sk); |
194 | } else { |
195 | rose->condition |= ROSE_COND_ACK_PENDING; |
196 | rose_start_hbtimer(sk); |
197 | } |
198 | break; |
199 | |
200 | default: |
201 | printk(KERN_WARNING "ROSE: unknown %02X in state 3\n" , frametype); |
202 | break; |
203 | } |
204 | |
205 | return queued; |
206 | } |
207 | |
208 | /* |
209 | * State machine for state 4, Awaiting Reset Confirmation State. |
210 | * The handling of the timer(s) is in file rose_timer.c |
211 | * Handling of state 0 and connection release is in af_rose.c. |
212 | */ |
213 | static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
214 | { |
215 | struct rose_sock *rose = rose_sk(sk); |
216 | |
217 | switch (frametype) { |
218 | case ROSE_RESET_REQUEST: |
219 | rose_write_internal(sk, ROSE_RESET_CONFIRMATION); |
220 | fallthrough; |
221 | case ROSE_RESET_CONFIRMATION: |
222 | rose_stop_timer(sk); |
223 | rose_start_idletimer(sk); |
224 | rose->condition = 0x00; |
225 | rose->va = 0; |
226 | rose->vr = 0; |
227 | rose->vs = 0; |
228 | rose->vl = 0; |
229 | rose->state = ROSE_STATE_3; |
230 | rose_requeue_frames(sk); |
231 | break; |
232 | |
233 | case ROSE_CLEAR_REQUEST: |
234 | rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); |
235 | rose_disconnect(sk, 0, skb->data[3], skb->data[4]); |
236 | rose->neighbour->use--; |
237 | break; |
238 | |
239 | default: |
240 | break; |
241 | } |
242 | |
243 | return 0; |
244 | } |
245 | |
246 | /* |
247 | * State machine for state 5, Awaiting Call Acceptance State. |
248 | * The handling of the timer(s) is in file rose_timer.c |
249 | * Handling of state 0 and connection release is in af_rose.c. |
250 | */ |
251 | static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
252 | { |
253 | if (frametype == ROSE_CLEAR_REQUEST) { |
254 | rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); |
255 | rose_disconnect(sk, 0, skb->data[3], skb->data[4]); |
256 | rose_sk(sk)->neighbour->use--; |
257 | } |
258 | |
259 | return 0; |
260 | } |
261 | |
262 | /* Higher level upcall for a LAPB frame */ |
263 | int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb) |
264 | { |
265 | struct rose_sock *rose = rose_sk(sk); |
266 | int queued = 0, frametype, ns, nr, q, d, m; |
267 | |
268 | if (rose->state == ROSE_STATE_0) |
269 | return 0; |
270 | |
271 | frametype = rose_decode(skb, &ns, &nr, &q, &d, &m); |
272 | |
273 | switch (rose->state) { |
274 | case ROSE_STATE_1: |
275 | queued = rose_state1_machine(sk, skb, frametype); |
276 | break; |
277 | case ROSE_STATE_2: |
278 | queued = rose_state2_machine(sk, skb, frametype); |
279 | break; |
280 | case ROSE_STATE_3: |
281 | queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m); |
282 | break; |
283 | case ROSE_STATE_4: |
284 | queued = rose_state4_machine(sk, skb, frametype); |
285 | break; |
286 | case ROSE_STATE_5: |
287 | queued = rose_state5_machine(sk, skb, frametype); |
288 | break; |
289 | } |
290 | |
291 | rose_kick(sk); |
292 | |
293 | return queued; |
294 | } |
295 | |