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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> | |
1da177e4 LT |
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> | |
c752f073 | 26 | #include <net/tcp_states.h> |
1da177e4 LT |
27 | #include <asm/uaccess.h> |
28 | #include <asm/system.h> | |
29 | #include <linux/fcntl.h> | |
30 | #include <linux/mm.h> | |
31 | #include <linux/interrupt.h> | |
32 | ||
33 | /* | |
34 | * This routine purges all the queues of frames. | |
35 | */ | |
36 | void ax25_clear_queues(ax25_cb *ax25) | |
37 | { | |
38 | skb_queue_purge(&ax25->write_queue); | |
39 | skb_queue_purge(&ax25->ack_queue); | |
40 | skb_queue_purge(&ax25->reseq_queue); | |
41 | skb_queue_purge(&ax25->frag_queue); | |
42 | } | |
43 | ||
44 | /* | |
45 | * This routine purges the input queue of those frames that have been | |
46 | * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the | |
47 | * SDL diagram. | |
48 | */ | |
49 | void ax25_frames_acked(ax25_cb *ax25, unsigned short nr) | |
50 | { | |
51 | struct sk_buff *skb; | |
52 | ||
53 | /* | |
54 | * Remove all the ack-ed frames from the ack queue. | |
55 | */ | |
56 | if (ax25->va != nr) { | |
57 | while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) { | |
528930b9 | 58 | skb = skb_dequeue(&ax25->ack_queue); |
1da177e4 LT |
59 | kfree_skb(skb); |
60 | ax25->va = (ax25->va + 1) % ax25->modulus; | |
61 | } | |
62 | } | |
63 | } | |
64 | ||
65 | void ax25_requeue_frames(ax25_cb *ax25) | |
66 | { | |
528930b9 | 67 | struct sk_buff *skb, *skb_prev = NULL; |
1da177e4 LT |
68 | |
69 | /* | |
70 | * Requeue all the un-ack-ed frames on the output queue to be picked | |
71 | * up by ax25_kick called from the timer. This arrangement handles the | |
72 | * possibility of an empty output queue. | |
73 | */ | |
74 | while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) { | |
75 | if (skb_prev == NULL) | |
76 | skb_queue_head(&ax25->write_queue, skb); | |
77 | else | |
8728b834 | 78 | skb_append(skb_prev, skb, &ax25->write_queue); |
1da177e4 LT |
79 | skb_prev = skb; |
80 | } | |
81 | } | |
82 | ||
83 | /* | |
84 | * Validate that the value of nr is between va and vs. Return true or | |
85 | * false for testing. | |
86 | */ | |
87 | int ax25_validate_nr(ax25_cb *ax25, unsigned short nr) | |
88 | { | |
89 | unsigned short vc = ax25->va; | |
90 | ||
91 | while (vc != ax25->vs) { | |
92 | if (nr == vc) return 1; | |
93 | vc = (vc + 1) % ax25->modulus; | |
94 | } | |
95 | ||
96 | if (nr == ax25->vs) return 1; | |
97 | ||
98 | return 0; | |
99 | } | |
100 | ||
101 | /* | |
102 | * This routine is the centralised routine for parsing the control | |
103 | * information for the different frame formats. | |
104 | */ | |
105 | int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf) | |
106 | { | |
107 | unsigned char *frame; | |
108 | int frametype = AX25_ILLEGAL; | |
109 | ||
110 | frame = skb->data; | |
111 | *ns = *nr = *pf = 0; | |
112 | ||
113 | if (ax25->modulus == AX25_MODULUS) { | |
114 | if ((frame[0] & AX25_S) == 0) { | |
115 | frametype = AX25_I; /* I frame - carries NR/NS/PF */ | |
116 | *ns = (frame[0] >> 1) & 0x07; | |
117 | *nr = (frame[0] >> 5) & 0x07; | |
118 | *pf = frame[0] & AX25_PF; | |
119 | } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ | |
120 | frametype = frame[0] & 0x0F; | |
121 | *nr = (frame[0] >> 5) & 0x07; | |
122 | *pf = frame[0] & AX25_PF; | |
123 | } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ | |
124 | frametype = frame[0] & ~AX25_PF; | |
125 | *pf = frame[0] & AX25_PF; | |
126 | } | |
127 | skb_pull(skb, 1); | |
128 | } else { | |
129 | if ((frame[0] & AX25_S) == 0) { | |
130 | frametype = AX25_I; /* I frame - carries NR/NS/PF */ | |
131 | *ns = (frame[0] >> 1) & 0x7F; | |
132 | *nr = (frame[1] >> 1) & 0x7F; | |
133 | *pf = frame[1] & AX25_EPF; | |
134 | skb_pull(skb, 2); | |
135 | } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ | |
136 | frametype = frame[0] & 0x0F; | |
137 | *nr = (frame[1] >> 1) & 0x7F; | |
138 | *pf = frame[1] & AX25_EPF; | |
139 | skb_pull(skb, 2); | |
140 | } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ | |
141 | frametype = frame[0] & ~AX25_PF; | |
142 | *pf = frame[0] & AX25_PF; | |
143 | skb_pull(skb, 1); | |
144 | } | |
145 | } | |
146 | ||
147 | return frametype; | |
148 | } | |
149 | ||
150 | /* | |
151 | * This routine is called when the HDLC layer internally generates a | |
152 | * command or response for the remote machine ( eg. RR, UA etc. ). | |
153 | * Only supervisory or unnumbered frames are processed. | |
154 | */ | |
155 | void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type) | |
156 | { | |
157 | struct sk_buff *skb; | |
158 | unsigned char *dptr; | |
159 | ||
160 | if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL) | |
161 | return; | |
162 | ||
163 | skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len); | |
164 | ||
c1d2bbe1 | 165 | skb_reset_network_header(skb); |
1da177e4 LT |
166 | |
167 | /* Assume a response - address structure for DTE */ | |
168 | if (ax25->modulus == AX25_MODULUS) { | |
169 | dptr = skb_put(skb, 1); | |
170 | *dptr = frametype; | |
171 | *dptr |= (poll_bit) ? AX25_PF : 0; | |
172 | if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */ | |
173 | *dptr |= (ax25->vr << 5); | |
174 | } else { | |
175 | if ((frametype & AX25_U) == AX25_U) { | |
176 | dptr = skb_put(skb, 1); | |
177 | *dptr = frametype; | |
178 | *dptr |= (poll_bit) ? AX25_PF : 0; | |
179 | } else { | |
180 | dptr = skb_put(skb, 2); | |
181 | dptr[0] = frametype; | |
182 | dptr[1] = (ax25->vr << 1); | |
183 | dptr[1] |= (poll_bit) ? AX25_EPF : 0; | |
184 | } | |
185 | } | |
186 | ||
187 | ax25_transmit_buffer(ax25, skb, type); | |
188 | } | |
189 | ||
190 | /* | |
191 | * Send a 'DM' to an unknown connection attempt, or an invalid caller. | |
192 | * | |
193 | * Note: src here is the sender, thus it's the target of the DM | |
194 | */ | |
195 | void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi) | |
196 | { | |
197 | struct sk_buff *skb; | |
198 | char *dptr; | |
199 | ax25_digi retdigi; | |
200 | ||
201 | if (dev == NULL) | |
202 | return; | |
203 | ||
204 | if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL) | |
205 | return; /* Next SABM will get DM'd */ | |
206 | ||
207 | skb_reserve(skb, dev->hard_header_len); | |
c1d2bbe1 | 208 | skb_reset_network_header(skb); |
1da177e4 LT |
209 | |
210 | ax25_digi_invert(digi, &retdigi); | |
211 | ||
212 | dptr = skb_put(skb, 1); | |
213 | ||
214 | *dptr = AX25_DM | AX25_PF; | |
215 | ||
216 | /* | |
217 | * Do the address ourselves | |
218 | */ | |
219 | dptr = skb_push(skb, ax25_addr_size(digi)); | |
220 | dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS); | |
221 | ||
29c4be51 | 222 | ax25_queue_xmit(skb, dev); |
1da177e4 LT |
223 | } |
224 | ||
225 | /* | |
226 | * Exponential backoff for AX.25 | |
227 | */ | |
228 | void ax25_calculate_t1(ax25_cb *ax25) | |
229 | { | |
230 | int n, t = 2; | |
231 | ||
232 | switch (ax25->backoff) { | |
233 | case 0: | |
234 | break; | |
235 | ||
236 | case 1: | |
237 | t += 2 * ax25->n2count; | |
238 | break; | |
239 | ||
240 | case 2: | |
241 | for (n = 0; n < ax25->n2count; n++) | |
242 | t *= 2; | |
243 | if (t > 8) t = 8; | |
244 | break; | |
245 | } | |
246 | ||
247 | ax25->t1 = t * ax25->rtt; | |
248 | } | |
249 | ||
250 | /* | |
251 | * Calculate the Round Trip Time | |
252 | */ | |
253 | void ax25_calculate_rtt(ax25_cb *ax25) | |
254 | { | |
255 | if (ax25->backoff == 0) | |
256 | return; | |
257 | ||
258 | if (ax25_t1timer_running(ax25) && ax25->n2count == 0) | |
259 | ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10; | |
260 | ||
261 | if (ax25->rtt < AX25_T1CLAMPLO) | |
262 | ax25->rtt = AX25_T1CLAMPLO; | |
263 | ||
264 | if (ax25->rtt > AX25_T1CLAMPHI) | |
265 | ax25->rtt = AX25_T1CLAMPHI; | |
266 | } | |
267 | ||
268 | void ax25_disconnect(ax25_cb *ax25, int reason) | |
269 | { | |
270 | ax25_clear_queues(ax25); | |
271 | ||
272 | ax25_stop_t1timer(ax25); | |
273 | ax25_stop_t2timer(ax25); | |
274 | ax25_stop_t3timer(ax25); | |
275 | ax25_stop_idletimer(ax25); | |
276 | ||
277 | ax25->state = AX25_STATE_0; | |
278 | ||
279 | ax25_link_failed(ax25, reason); | |
280 | ||
281 | if (ax25->sk != NULL) { | |
282 | bh_lock_sock(ax25->sk); | |
283 | ax25->sk->sk_state = TCP_CLOSE; | |
284 | ax25->sk->sk_err = reason; | |
285 | ax25->sk->sk_shutdown |= SEND_SHUTDOWN; | |
286 | if (!sock_flag(ax25->sk, SOCK_DEAD)) { | |
287 | ax25->sk->sk_state_change(ax25->sk); | |
288 | sock_set_flag(ax25->sk, SOCK_DEAD); | |
289 | } | |
290 | bh_unlock_sock(ax25->sk); | |
291 | } | |
292 | } |