1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 *
4 * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
5 */
6 #include <linux/errno.h>
7 #include <linux/types.h>
8 #include <linux/socket.h>
9 #include <linux/in.h>
10 #include <linux/kernel.h>
11 #include <linux/timer.h>
12 #include <linux/string.h>
13 #include <linux/sockios.h>
14 #include <linux/net.h>
15 #include <linux/slab.h>
16 #include <net/ax25.h>
17 #include <linux/inet.h>
18 #include <linux/netdevice.h>
19 #include <linux/skbuff.h>
20 #include <net/sock.h>
21 #include <net/tcp_states.h>
22 #include <linux/uaccess.h>
23 #include <linux/fcntl.h>
24 #include <linux/mm.h>
25 #include <linux/interrupt.h>
26 #include <net/netrom.h>
27
28 /*
29 * This routine purges all of the queues of frames.
30 */
31 void nr_clear_queues(struct sock *sk)
32 {
33 struct nr_sock *nr = nr_sk(sk);
34
35 skb_queue_purge(&sk->sk_write_queue);
36 skb_queue_purge(&nr->ack_queue);
37 skb_queue_purge(&nr->reseq_queue);
38 skb_queue_purge(&nr->frag_queue);
39 }
40
41 /*
42 * This routine purges the input queue of those frames that have been
43 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
44 * SDL diagram.
45 */
46 void nr_frames_acked(struct sock *sk, unsigned short nr)
47 {
48 struct nr_sock *nrom = nr_sk(sk);
49 struct sk_buff *skb;
50
51 /*
52 * Remove all the ack-ed frames from the ack queue.
53 */
54 if (nrom->va != nr) {
55 while (skb_peek(&nrom->ack_queue) != NULL && nrom->va != nr) {
56 skb = skb_dequeue(&nrom->ack_queue);
57 kfree_skb(skb);
58 nrom->va = (nrom->va + 1) % NR_MODULUS;
59 }
60 }
61 }
62
63 /*
64 * Requeue all the un-ack-ed frames on the output queue to be picked
65 * up by nr_kick called from the timer. This arrangement handles the
66 * possibility of an empty output queue.
67 */
68 void nr_requeue_frames(struct sock *sk)
69 {
70 struct sk_buff *skb, *skb_prev = NULL;
71
72 while ((skb = skb_dequeue(&nr_sk(sk)->ack_queue)) != NULL) {
73 if (skb_prev == NULL)
74 skb_queue_head(&sk->sk_write_queue, skb);
75 else
76 skb_append(skb_prev, skb, &sk->sk_write_queue);
77 skb_prev = skb;
78 }
79 }
80
81 /*
82 * Validate that the value of nr is between va and vs. Return true or
83 * false for testing.
84 */
85 int nr_validate_nr(struct sock *sk, unsigned short nr)
86 {
87 struct nr_sock *nrom = nr_sk(sk);
88 unsigned short vc = nrom->va;
89
90 while (vc != nrom->vs) {
91 if (nr == vc) return 1;
92 vc = (vc + 1) % NR_MODULUS;
93 }
94
95 return nr == nrom->vs;
96 }
97
98 /*
99 * Check that ns is within the receive window.
100 */
101 int nr_in_rx_window(struct sock *sk, unsigned short ns)
102 {
103 struct nr_sock *nr = nr_sk(sk);
104 unsigned short vc = nr->vr;
105 unsigned short vt = (nr->vl + nr->window) % NR_MODULUS;
106
107 while (vc != vt) {
108 if (ns == vc) return 1;
109 vc = (vc + 1) % NR_MODULUS;
110 }
111
112 return 0;
113 }
114
115 /*
116 * This routine is called when the HDLC layer internally generates a
117 * control frame.
118 */
119 void nr_write_internal(struct sock *sk, int frametype)
120 {
121 struct nr_sock *nr = nr_sk(sk);
122 struct sk_buff *skb;
123 unsigned char *dptr;
124 int len, timeout;
125
126 len = NR_TRANSPORT_LEN;
127
128 switch (frametype & 0x0F) {
129 case NR_CONNREQ:
130 len += 17;
131 break;
132 case NR_CONNACK:
133 len += (nr->bpqext) ? 2 : 1;
134 break;
135 case NR_DISCREQ:
136 case NR_DISCACK:
137 case NR_INFOACK:
138 break;
139 default:
140 printk(KERN_ERR "NET/ROM: nr_write_internal - invalid frame type %d\n", frametype);
141 return;
142 }
143
144 skb = alloc_skb(NR_NETWORK_LEN + len, GFP_ATOMIC);
145 if (!skb)
146 return;
147
148 /*
149 * Space for AX.25 and NET/ROM network header
150 */
151 skb_reserve(skb, NR_NETWORK_LEN);
152
153 dptr = skb_put(skb, len);
154
155 switch (frametype & 0x0F) {
156 case NR_CONNREQ:
157 timeout = nr->t1 / HZ;
158 *dptr++ = nr->my_index;
159 *dptr++ = nr->my_id;
160 *dptr++ = 0;
161 *dptr++ = 0;
162 *dptr++ = frametype;
163 *dptr++ = nr->window;
164 memcpy(dptr, &nr->user_addr, AX25_ADDR_LEN);
165 dptr[6] &= ~AX25_CBIT;
166 dptr[6] &= ~AX25_EBIT;
167 dptr[6] |= AX25_SSSID_SPARE;
168 dptr += AX25_ADDR_LEN;
169 memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
170 dptr[6] &= ~AX25_CBIT;
171 dptr[6] &= ~AX25_EBIT;
172 dptr[6] |= AX25_SSSID_SPARE;
173 dptr += AX25_ADDR_LEN;
174 *dptr++ = timeout % 256;
175 *dptr++ = timeout / 256;
176 break;
177
178 case NR_CONNACK:
179 *dptr++ = nr->your_index;
180 *dptr++ = nr->your_id;
181 *dptr++ = nr->my_index;
182 *dptr++ = nr->my_id;
183 *dptr++ = frametype;
184 *dptr++ = nr->window;
185 if (nr->bpqext)
186 *dptr++ = READ_ONCE(sysctl_netrom_network_ttl_initialiser);
187 break;
188
189 case NR_DISCREQ:
190 case NR_DISCACK:
191 *dptr++ = nr->your_index;
192 *dptr++ = nr->your_id;
193 *dptr++ = 0;
194 *dptr++ = 0;
195 *dptr++ = frametype;
196 break;
197
198 case NR_INFOACK:
199 *dptr++ = nr->your_index;
200 *dptr++ = nr->your_id;
201 *dptr++ = 0;
202 *dptr++ = nr->vr;
203 *dptr++ = frametype;
204 break;
205 }
206
207 nr_transmit_buffer(sk, skb);
208 }
209
210 /*
211 * This routine is called to send an error reply.
212 */
213 void __nr_transmit_reply(struct sk_buff *skb, int mine, unsigned char cmdflags)
214 {
215 struct sk_buff *skbn;
216 unsigned char *dptr;
217 int len;
218
219 len = NR_NETWORK_LEN + NR_TRANSPORT_LEN + 1;
220
221 if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL)
222 return;
223
224 skb_reserve(skbn, 0);
225
226 dptr = skb_put(skbn, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
227
228 skb_copy_from_linear_data_offset(skb, 7, dptr, AX25_ADDR_LEN);
229 dptr[6] &= ~AX25_CBIT;
230 dptr[6] &= ~AX25_EBIT;
231 dptr[6] |= AX25_SSSID_SPARE;
232 dptr += AX25_ADDR_LEN;
233
234 skb_copy_from_linear_data(skb, dptr, AX25_ADDR_LEN);
235 dptr[6] &= ~AX25_CBIT;
236 dptr[6] |= AX25_EBIT;
237 dptr[6] |= AX25_SSSID_SPARE;
238 dptr += AX25_ADDR_LEN;
239
240 *dptr++ = READ_ONCE(sysctl_netrom_network_ttl_initialiser);
241
242 if (mine) {
243 *dptr++ = 0;
244 *dptr++ = 0;
245 *dptr++ = skb->data[15];
246 *dptr++ = skb->data[16];
247 } else {
248 *dptr++ = skb->data[15];
249 *dptr++ = skb->data[16];
250 *dptr++ = 0;
251 *dptr++ = 0;
252 }
253
254 *dptr++ = cmdflags;
255 *dptr++ = 0;
256
257 if (!nr_route_frame(skbn, NULL))
258 kfree_skb(skbn);
259 }
260
261 void nr_disconnect(struct sock *sk, int reason)
262 {
263 nr_stop_t1timer(sk);
264 nr_stop_t2timer(sk);
265 nr_stop_t4timer(sk);
266 nr_stop_idletimer(sk);
267
268 nr_clear_queues(sk);
269
270 nr_sk(sk)->state = NR_STATE_0;
271
272 sk->sk_state = TCP_CLOSE;
273 sk->sk_err = reason;
274 sk->sk_shutdown |= SEND_SHUTDOWN;
275
276 if (!sock_flag(sk, SOCK_DEAD)) {
277 sk->sk_state_change(sk);
278 sock_set_flag(sk, SOCK_DEAD);
279 }
280 }
281
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