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1da177e4 LT |
1 | /* |
2 | * This program is free software; you can redistribute it and/or modify | |
3 | * it under the terms of the GNU General Public License as published by | |
4 | * the Free Software Foundation; either version 2 of the License, or | |
5 | * (at your option) any later version. | |
6 | * | |
7 | * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk) | |
8 | * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) | |
9 | * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de) | |
10 | * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr) | |
11 | */ | |
12 | #include <linux/errno.h> | |
13 | #include <linux/types.h> | |
14 | #include <linux/socket.h> | |
15 | #include <linux/in.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/sched.h> | |
18 | #include <linux/timer.h> | |
19 | #include <linux/string.h> | |
20 | #include <linux/sockios.h> | |
21 | #include <linux/net.h> | |
22 | #include <net/ax25.h> | |
23 | #include <linux/inet.h> | |
24 | #include <linux/netdevice.h> | |
25 | #include <linux/skbuff.h> | |
26 | #include <net/sock.h> | |
27 | #include <net/tcp.h> | |
28 | #include <asm/uaccess.h> | |
29 | #include <asm/system.h> | |
30 | #include <linux/fcntl.h> | |
31 | #include <linux/mm.h> | |
32 | #include <linux/interrupt.h> | |
33 | ||
34 | /* | |
35 | * This routine purges all the queues of frames. | |
36 | */ | |
37 | void ax25_clear_queues(ax25_cb *ax25) | |
38 | { | |
39 | skb_queue_purge(&ax25->write_queue); | |
40 | skb_queue_purge(&ax25->ack_queue); | |
41 | skb_queue_purge(&ax25->reseq_queue); | |
42 | skb_queue_purge(&ax25->frag_queue); | |
43 | } | |
44 | ||
45 | /* | |
46 | * This routine purges the input queue of those frames that have been | |
47 | * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the | |
48 | * SDL diagram. | |
49 | */ | |
50 | void ax25_frames_acked(ax25_cb *ax25, unsigned short nr) | |
51 | { | |
52 | struct sk_buff *skb; | |
53 | ||
54 | /* | |
55 | * Remove all the ack-ed frames from the ack queue. | |
56 | */ | |
57 | if (ax25->va != nr) { | |
58 | while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) { | |
59 | skb = skb_dequeue(&ax25->ack_queue); | |
60 | kfree_skb(skb); | |
61 | ax25->va = (ax25->va + 1) % ax25->modulus; | |
62 | } | |
63 | } | |
64 | } | |
65 | ||
66 | void ax25_requeue_frames(ax25_cb *ax25) | |
67 | { | |
68 | struct sk_buff *skb, *skb_prev = NULL; | |
69 | ||
70 | /* | |
71 | * Requeue all the un-ack-ed frames on the output queue to be picked | |
72 | * up by ax25_kick called from the timer. This arrangement handles the | |
73 | * possibility of an empty output queue. | |
74 | */ | |
75 | while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) { | |
76 | if (skb_prev == NULL) | |
77 | skb_queue_head(&ax25->write_queue, skb); | |
78 | else | |
79 | skb_append(skb_prev, skb); | |
80 | skb_prev = skb; | |
81 | } | |
82 | } | |
83 | ||
84 | /* | |
85 | * Validate that the value of nr is between va and vs. Return true or | |
86 | * false for testing. | |
87 | */ | |
88 | int ax25_validate_nr(ax25_cb *ax25, unsigned short nr) | |
89 | { | |
90 | unsigned short vc = ax25->va; | |
91 | ||
92 | while (vc != ax25->vs) { | |
93 | if (nr == vc) return 1; | |
94 | vc = (vc + 1) % ax25->modulus; | |
95 | } | |
96 | ||
97 | if (nr == ax25->vs) return 1; | |
98 | ||
99 | return 0; | |
100 | } | |
101 | ||
102 | /* | |
103 | * This routine is the centralised routine for parsing the control | |
104 | * information for the different frame formats. | |
105 | */ | |
106 | int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf) | |
107 | { | |
108 | unsigned char *frame; | |
109 | int frametype = AX25_ILLEGAL; | |
110 | ||
111 | frame = skb->data; | |
112 | *ns = *nr = *pf = 0; | |
113 | ||
114 | if (ax25->modulus == AX25_MODULUS) { | |
115 | if ((frame[0] & AX25_S) == 0) { | |
116 | frametype = AX25_I; /* I frame - carries NR/NS/PF */ | |
117 | *ns = (frame[0] >> 1) & 0x07; | |
118 | *nr = (frame[0] >> 5) & 0x07; | |
119 | *pf = frame[0] & AX25_PF; | |
120 | } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ | |
121 | frametype = frame[0] & 0x0F; | |
122 | *nr = (frame[0] >> 5) & 0x07; | |
123 | *pf = frame[0] & AX25_PF; | |
124 | } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ | |
125 | frametype = frame[0] & ~AX25_PF; | |
126 | *pf = frame[0] & AX25_PF; | |
127 | } | |
128 | skb_pull(skb, 1); | |
129 | } else { | |
130 | if ((frame[0] & AX25_S) == 0) { | |
131 | frametype = AX25_I; /* I frame - carries NR/NS/PF */ | |
132 | *ns = (frame[0] >> 1) & 0x7F; | |
133 | *nr = (frame[1] >> 1) & 0x7F; | |
134 | *pf = frame[1] & AX25_EPF; | |
135 | skb_pull(skb, 2); | |
136 | } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ | |
137 | frametype = frame[0] & 0x0F; | |
138 | *nr = (frame[1] >> 1) & 0x7F; | |
139 | *pf = frame[1] & AX25_EPF; | |
140 | skb_pull(skb, 2); | |
141 | } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ | |
142 | frametype = frame[0] & ~AX25_PF; | |
143 | *pf = frame[0] & AX25_PF; | |
144 | skb_pull(skb, 1); | |
145 | } | |
146 | } | |
147 | ||
148 | return frametype; | |
149 | } | |
150 | ||
151 | /* | |
152 | * This routine is called when the HDLC layer internally generates a | |
153 | * command or response for the remote machine ( eg. RR, UA etc. ). | |
154 | * Only supervisory or unnumbered frames are processed. | |
155 | */ | |
156 | void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type) | |
157 | { | |
158 | struct sk_buff *skb; | |
159 | unsigned char *dptr; | |
160 | ||
161 | if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL) | |
162 | return; | |
163 | ||
164 | skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len); | |
165 | ||
166 | skb->nh.raw = skb->data; | |
167 | ||
168 | /* Assume a response - address structure for DTE */ | |
169 | if (ax25->modulus == AX25_MODULUS) { | |
170 | dptr = skb_put(skb, 1); | |
171 | *dptr = frametype; | |
172 | *dptr |= (poll_bit) ? AX25_PF : 0; | |
173 | if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */ | |
174 | *dptr |= (ax25->vr << 5); | |
175 | } else { | |
176 | if ((frametype & AX25_U) == AX25_U) { | |
177 | dptr = skb_put(skb, 1); | |
178 | *dptr = frametype; | |
179 | *dptr |= (poll_bit) ? AX25_PF : 0; | |
180 | } else { | |
181 | dptr = skb_put(skb, 2); | |
182 | dptr[0] = frametype; | |
183 | dptr[1] = (ax25->vr << 1); | |
184 | dptr[1] |= (poll_bit) ? AX25_EPF : 0; | |
185 | } | |
186 | } | |
187 | ||
188 | ax25_transmit_buffer(ax25, skb, type); | |
189 | } | |
190 | ||
191 | /* | |
192 | * Send a 'DM' to an unknown connection attempt, or an invalid caller. | |
193 | * | |
194 | * Note: src here is the sender, thus it's the target of the DM | |
195 | */ | |
196 | void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi) | |
197 | { | |
198 | struct sk_buff *skb; | |
199 | char *dptr; | |
200 | ax25_digi retdigi; | |
201 | ||
202 | if (dev == NULL) | |
203 | return; | |
204 | ||
205 | if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL) | |
206 | return; /* Next SABM will get DM'd */ | |
207 | ||
208 | skb_reserve(skb, dev->hard_header_len); | |
209 | skb->nh.raw = skb->data; | |
210 | ||
211 | ax25_digi_invert(digi, &retdigi); | |
212 | ||
213 | dptr = skb_put(skb, 1); | |
214 | ||
215 | *dptr = AX25_DM | AX25_PF; | |
216 | ||
217 | /* | |
218 | * Do the address ourselves | |
219 | */ | |
220 | dptr = skb_push(skb, ax25_addr_size(digi)); | |
221 | dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS); | |
222 | ||
29c4be51 | 223 | ax25_queue_xmit(skb, dev); |
1da177e4 LT |
224 | } |
225 | ||
226 | /* | |
227 | * Exponential backoff for AX.25 | |
228 | */ | |
229 | void ax25_calculate_t1(ax25_cb *ax25) | |
230 | { | |
231 | int n, t = 2; | |
232 | ||
233 | switch (ax25->backoff) { | |
234 | case 0: | |
235 | break; | |
236 | ||
237 | case 1: | |
238 | t += 2 * ax25->n2count; | |
239 | break; | |
240 | ||
241 | case 2: | |
242 | for (n = 0; n < ax25->n2count; n++) | |
243 | t *= 2; | |
244 | if (t > 8) t = 8; | |
245 | break; | |
246 | } | |
247 | ||
248 | ax25->t1 = t * ax25->rtt; | |
249 | } | |
250 | ||
251 | /* | |
252 | * Calculate the Round Trip Time | |
253 | */ | |
254 | void ax25_calculate_rtt(ax25_cb *ax25) | |
255 | { | |
256 | if (ax25->backoff == 0) | |
257 | return; | |
258 | ||
259 | if (ax25_t1timer_running(ax25) && ax25->n2count == 0) | |
260 | ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10; | |
261 | ||
262 | if (ax25->rtt < AX25_T1CLAMPLO) | |
263 | ax25->rtt = AX25_T1CLAMPLO; | |
264 | ||
265 | if (ax25->rtt > AX25_T1CLAMPHI) | |
266 | ax25->rtt = AX25_T1CLAMPHI; | |
267 | } | |
268 | ||
269 | void ax25_disconnect(ax25_cb *ax25, int reason) | |
270 | { | |
271 | ax25_clear_queues(ax25); | |
272 | ||
273 | ax25_stop_t1timer(ax25); | |
274 | ax25_stop_t2timer(ax25); | |
275 | ax25_stop_t3timer(ax25); | |
276 | ax25_stop_idletimer(ax25); | |
277 | ||
278 | ax25->state = AX25_STATE_0; | |
279 | ||
280 | ax25_link_failed(ax25, reason); | |
281 | ||
282 | if (ax25->sk != NULL) { | |
283 | bh_lock_sock(ax25->sk); | |
284 | ax25->sk->sk_state = TCP_CLOSE; | |
285 | ax25->sk->sk_err = reason; | |
286 | ax25->sk->sk_shutdown |= SEND_SHUTDOWN; | |
287 | if (!sock_flag(ax25->sk, SOCK_DEAD)) { | |
288 | ax25->sk->sk_state_change(ax25->sk); | |
289 | sock_set_flag(ax25->sk, SOCK_DEAD); | |
290 | } | |
291 | bh_unlock_sock(ax25->sk); | |
292 | } | |
293 | } |