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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/timer.h> |
18 | #include <linux/string.h> |
19 | #include <linux/sockios.h> |
20 | #include <linux/net.h> |
21 | #include <linux/slab.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_states.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; |
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_tail(&ax25->ack_queue)) != NULL) |
76 | skb_queue_head(&ax25->write_queue, skb); |
77 | } |
78 | |
79 | /* |
80 | * Validate that the value of nr is between va and vs. Return true or |
81 | * false for testing. |
82 | */ |
83 | int ax25_validate_nr(ax25_cb *ax25, unsigned short nr) |
84 | { |
85 | unsigned short vc = ax25->va; |
86 | |
87 | while (vc != ax25->vs) { |
88 | if (nr == vc) return 1; |
89 | vc = (vc + 1) % ax25->modulus; |
90 | } |
91 | |
92 | if (nr == ax25->vs) return 1; |
93 | |
94 | return 0; |
95 | } |
96 | |
97 | /* |
98 | * This routine is the centralised routine for parsing the control |
99 | * information for the different frame formats. |
100 | */ |
101 | int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf) |
102 | { |
103 | unsigned char *frame; |
104 | int frametype = AX25_ILLEGAL; |
105 | |
106 | frame = skb->data; |
107 | *ns = *nr = *pf = 0; |
108 | |
109 | if (ax25->modulus == AX25_MODULUS) { |
110 | if ((frame[0] & AX25_S) == 0) { |
111 | frametype = AX25_I; /* I frame - carries NR/NS/PF */ |
112 | *ns = (frame[0] >> 1) & 0x07; |
113 | *nr = (frame[0] >> 5) & 0x07; |
114 | *pf = frame[0] & AX25_PF; |
115 | } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ |
116 | frametype = frame[0] & 0x0F; |
117 | *nr = (frame[0] >> 5) & 0x07; |
118 | *pf = frame[0] & AX25_PF; |
119 | } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ |
120 | frametype = frame[0] & ~AX25_PF; |
121 | *pf = frame[0] & AX25_PF; |
122 | } |
123 | skb_pull(skb, 1); |
124 | } else { |
125 | if ((frame[0] & AX25_S) == 0) { |
126 | frametype = AX25_I; /* I frame - carries NR/NS/PF */ |
127 | *ns = (frame[0] >> 1) & 0x7F; |
128 | *nr = (frame[1] >> 1) & 0x7F; |
129 | *pf = frame[1] & AX25_EPF; |
130 | skb_pull(skb, 2); |
131 | } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ |
132 | frametype = frame[0] & 0x0F; |
133 | *nr = (frame[1] >> 1) & 0x7F; |
134 | *pf = frame[1] & AX25_EPF; |
135 | skb_pull(skb, 2); |
136 | } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ |
137 | frametype = frame[0] & ~AX25_PF; |
138 | *pf = frame[0] & AX25_PF; |
139 | skb_pull(skb, 1); |
140 | } |
141 | } |
142 | |
143 | return frametype; |
144 | } |
145 | |
146 | /* |
147 | * This routine is called when the HDLC layer internally generates a |
148 | * command or response for the remote machine ( eg. RR, UA etc. ). |
149 | * Only supervisory or unnumbered frames are processed. |
150 | */ |
151 | void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type) |
152 | { |
153 | struct sk_buff *skb; |
154 | unsigned char *dptr; |
155 | |
156 | if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL) |
157 | return; |
158 | |
159 | skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len); |
160 | |
161 | skb_reset_network_header(skb); |
162 | |
163 | /* Assume a response - address structure for DTE */ |
164 | if (ax25->modulus == AX25_MODULUS) { |
165 | dptr = skb_put(skb, 1); |
166 | *dptr = frametype; |
167 | *dptr |= (poll_bit) ? AX25_PF : 0; |
168 | if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */ |
169 | *dptr |= (ax25->vr << 5); |
170 | } else { |
171 | if ((frametype & AX25_U) == AX25_U) { |
172 | dptr = skb_put(skb, 1); |
173 | *dptr = frametype; |
174 | *dptr |= (poll_bit) ? AX25_PF : 0; |
175 | } else { |
176 | dptr = skb_put(skb, 2); |
177 | dptr[0] = frametype; |
178 | dptr[1] = (ax25->vr << 1); |
179 | dptr[1] |= (poll_bit) ? AX25_EPF : 0; |
180 | } |
181 | } |
182 | |
183 | ax25_transmit_buffer(ax25, skb, type); |
184 | } |
185 | |
186 | /* |
187 | * Send a 'DM' to an unknown connection attempt, or an invalid caller. |
188 | * |
189 | * Note: src here is the sender, thus it's the target of the DM |
190 | */ |
191 | void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi) |
192 | { |
193 | struct sk_buff *skb; |
194 | char *dptr; |
195 | ax25_digi retdigi; |
196 | |
197 | if (dev == NULL) |
198 | return; |
199 | |
200 | if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL) |
201 | return; /* Next SABM will get DM'd */ |
202 | |
203 | skb_reserve(skb, dev->hard_header_len); |
204 | skb_reset_network_header(skb); |
205 | |
206 | ax25_digi_invert(digi, &retdigi); |
207 | |
208 | dptr = skb_put(skb, 1); |
209 | |
210 | *dptr = AX25_DM | AX25_PF; |
211 | |
212 | /* |
213 | * Do the address ourselves |
214 | */ |
215 | dptr = skb_push(skb, ax25_addr_size(digi)); |
216 | dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS); |
217 | |
218 | ax25_queue_xmit(skb, dev); |
219 | } |
220 | |
221 | /* |
222 | * Exponential backoff for AX.25 |
223 | */ |
224 | void ax25_calculate_t1(ax25_cb *ax25) |
225 | { |
226 | int n, t = 2; |
227 | |
228 | switch (ax25->backoff) { |
229 | case 0: |
230 | break; |
231 | |
232 | case 1: |
233 | t += 2 * ax25->n2count; |
234 | break; |
235 | |
236 | case 2: |
237 | for (n = 0; n < ax25->n2count; n++) |
238 | t *= 2; |
239 | if (t > 8) t = 8; |
240 | break; |
241 | } |
242 | |
243 | ax25->t1 = t * ax25->rtt; |
244 | } |
245 | |
246 | /* |
247 | * Calculate the Round Trip Time |
248 | */ |
249 | void ax25_calculate_rtt(ax25_cb *ax25) |
250 | { |
251 | if (ax25->backoff == 0) |
252 | return; |
253 | |
254 | if (ax25_t1timer_running(ax25) && ax25->n2count == 0) |
255 | ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10; |
256 | |
257 | if (ax25->rtt < AX25_T1CLAMPLO) |
258 | ax25->rtt = AX25_T1CLAMPLO; |
259 | |
260 | if (ax25->rtt > AX25_T1CLAMPHI) |
261 | ax25->rtt = AX25_T1CLAMPHI; |
262 | } |
263 | |
264 | void ax25_disconnect(ax25_cb *ax25, int reason) |
265 | { |
266 | ax25_clear_queues(ax25); |
267 | |
268 | ax25_stop_t1timer(ax25); |
269 | ax25_stop_t2timer(ax25); |
270 | ax25_stop_t3timer(ax25); |
271 | ax25_stop_idletimer(ax25); |
272 | |
273 | ax25->state = AX25_STATE_0; |
274 | |
275 | ax25_link_failed(ax25, reason); |
276 | |
277 | if (ax25->sk != NULL) { |
278 | local_bh_disable(); |
279 | bh_lock_sock(ax25->sk); |
280 | ax25->sk->sk_state = TCP_CLOSE; |
281 | ax25->sk->sk_err = reason; |
282 | ax25->sk->sk_shutdown |= SEND_SHUTDOWN; |
283 | if (!sock_flag(ax25->sk, SOCK_DEAD)) { |
284 | ax25->sk->sk_state_change(ax25->sk); |
285 | sock_set_flag(ax25->sk, SOCK_DEAD); |
286 | } |
287 | bh_unlock_sock(ax25->sk); |
288 | local_bh_enable(); |
289 | } |
290 | } |
291 |
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Tags:
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v2.6.34-rc5
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