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1da177e4 LT |
1 | /* |
2 | * LAPB release 002 | |
3 | * | |
4 | * This code REQUIRES 2.1.15 or higher/ NET3.038 | |
5 | * | |
6 | * This module: | |
7 | * This module is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version | |
10 | * 2 of the License, or (at your option) any later version. | |
11 | * | |
12 | * History | |
13 | * LAPB 001 Jonathan Naylor Started Coding | |
14 | */ | |
15 | ||
a508da6c JP |
16 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
17 | ||
1da177e4 LT |
18 | #include <linux/errno.h> |
19 | #include <linux/types.h> | |
20 | #include <linux/socket.h> | |
21 | #include <linux/in.h> | |
22 | #include <linux/kernel.h> | |
1da177e4 LT |
23 | #include <linux/timer.h> |
24 | #include <linux/string.h> | |
25 | #include <linux/sockios.h> | |
26 | #include <linux/net.h> | |
27 | #include <linux/inet.h> | |
28 | #include <linux/skbuff.h> | |
5a0e3ad6 | 29 | #include <linux/slab.h> |
1da177e4 LT |
30 | #include <net/sock.h> |
31 | #include <asm/uaccess.h> | |
1da177e4 LT |
32 | #include <linux/fcntl.h> |
33 | #include <linux/mm.h> | |
34 | #include <linux/interrupt.h> | |
35 | #include <net/lapb.h> | |
36 | ||
37 | /* | |
38 | * This routine purges all the queues of frames. | |
39 | */ | |
40 | void lapb_clear_queues(struct lapb_cb *lapb) | |
41 | { | |
42 | skb_queue_purge(&lapb->write_queue); | |
43 | skb_queue_purge(&lapb->ack_queue); | |
44 | } | |
45 | ||
46 | /* | |
47 | * This routine purges the input queue of those frames that have been | |
48 | * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the | |
49 | * SDL diagram. | |
50 | */ | |
51 | void lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr) | |
52 | { | |
53 | struct sk_buff *skb; | |
54 | int modulus; | |
55 | ||
56 | modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; | |
57 | ||
58 | /* | |
59 | * Remove all the ack-ed frames from the ack queue. | |
60 | */ | |
61 | if (lapb->va != nr) | |
62 | while (skb_peek(&lapb->ack_queue) && lapb->va != nr) { | |
56d6c3d7 | 63 | skb = skb_dequeue(&lapb->ack_queue); |
1da177e4 LT |
64 | kfree_skb(skb); |
65 | lapb->va = (lapb->va + 1) % modulus; | |
66 | } | |
67 | } | |
68 | ||
69 | void lapb_requeue_frames(struct lapb_cb *lapb) | |
70 | { | |
56d6c3d7 | 71 | struct sk_buff *skb, *skb_prev = NULL; |
1da177e4 LT |
72 | |
73 | /* | |
74 | * Requeue all the un-ack-ed frames on the output queue to be picked | |
75 | * up by lapb_kick called from the timer. This arrangement handles the | |
76 | * possibility of an empty output queue. | |
77 | */ | |
78 | while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) { | |
79 | if (!skb_prev) | |
80 | skb_queue_head(&lapb->write_queue, skb); | |
81 | else | |
8728b834 | 82 | skb_append(skb_prev, skb, &lapb->write_queue); |
1da177e4 LT |
83 | skb_prev = skb; |
84 | } | |
85 | } | |
86 | ||
87 | /* | |
88 | * Validate that the value of nr is between va and vs. Return true or | |
89 | * false for testing. | |
90 | */ | |
91 | int lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr) | |
92 | { | |
93 | unsigned short vc = lapb->va; | |
94 | int modulus; | |
56d6c3d7 | 95 | |
1da177e4 LT |
96 | modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; |
97 | ||
98 | while (vc != lapb->vs) { | |
99 | if (nr == vc) | |
100 | return 1; | |
101 | vc = (vc + 1) % modulus; | |
102 | } | |
56d6c3d7 | 103 | |
1da177e4 LT |
104 | return nr == lapb->vs; |
105 | } | |
106 | ||
107 | /* | |
108 | * This routine is the centralised routine for parsing the control | |
109 | * information for the different frame formats. | |
110 | */ | |
111 | int lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb, | |
112 | struct lapb_frame *frame) | |
113 | { | |
114 | frame->type = LAPB_ILLEGAL; | |
115 | ||
0d08df6c | 116 | lapb_dbg(2, "(%p) S%d RX %3ph\n", lapb->dev, lapb->state, skb->data); |
1da177e4 LT |
117 | |
118 | /* We always need to look at 2 bytes, sometimes we need | |
119 | * to look at 3 and those cases are handled below. | |
120 | */ | |
121 | if (!pskb_may_pull(skb, 2)) | |
122 | return -1; | |
123 | ||
124 | if (lapb->mode & LAPB_MLP) { | |
125 | if (lapb->mode & LAPB_DCE) { | |
126 | if (skb->data[0] == LAPB_ADDR_D) | |
127 | frame->cr = LAPB_COMMAND; | |
128 | if (skb->data[0] == LAPB_ADDR_C) | |
129 | frame->cr = LAPB_RESPONSE; | |
130 | } else { | |
131 | if (skb->data[0] == LAPB_ADDR_C) | |
132 | frame->cr = LAPB_COMMAND; | |
133 | if (skb->data[0] == LAPB_ADDR_D) | |
134 | frame->cr = LAPB_RESPONSE; | |
135 | } | |
136 | } else { | |
137 | if (lapb->mode & LAPB_DCE) { | |
138 | if (skb->data[0] == LAPB_ADDR_B) | |
139 | frame->cr = LAPB_COMMAND; | |
140 | if (skb->data[0] == LAPB_ADDR_A) | |
141 | frame->cr = LAPB_RESPONSE; | |
142 | } else { | |
143 | if (skb->data[0] == LAPB_ADDR_A) | |
144 | frame->cr = LAPB_COMMAND; | |
145 | if (skb->data[0] == LAPB_ADDR_B) | |
146 | frame->cr = LAPB_RESPONSE; | |
147 | } | |
148 | } | |
56d6c3d7 | 149 | |
1da177e4 LT |
150 | skb_pull(skb, 1); |
151 | ||
152 | if (lapb->mode & LAPB_EXTENDED) { | |
153 | if (!(skb->data[0] & LAPB_S)) { | |
154 | if (!pskb_may_pull(skb, 2)) | |
155 | return -1; | |
156 | /* | |
157 | * I frame - carries NR/NS/PF | |
158 | */ | |
159 | frame->type = LAPB_I; | |
160 | frame->ns = (skb->data[0] >> 1) & 0x7F; | |
161 | frame->nr = (skb->data[1] >> 1) & 0x7F; | |
162 | frame->pf = skb->data[1] & LAPB_EPF; | |
163 | frame->control[0] = skb->data[0]; | |
164 | frame->control[1] = skb->data[1]; | |
165 | skb_pull(skb, 2); | |
166 | } else if ((skb->data[0] & LAPB_U) == 1) { | |
167 | if (!pskb_may_pull(skb, 2)) | |
168 | return -1; | |
169 | /* | |
170 | * S frame - take out PF/NR | |
171 | */ | |
172 | frame->type = skb->data[0] & 0x0F; | |
173 | frame->nr = (skb->data[1] >> 1) & 0x7F; | |
174 | frame->pf = skb->data[1] & LAPB_EPF; | |
175 | frame->control[0] = skb->data[0]; | |
176 | frame->control[1] = skb->data[1]; | |
177 | skb_pull(skb, 2); | |
178 | } else if ((skb->data[0] & LAPB_U) == 3) { | |
179 | /* | |
180 | * U frame - take out PF | |
181 | */ | |
182 | frame->type = skb->data[0] & ~LAPB_SPF; | |
183 | frame->pf = skb->data[0] & LAPB_SPF; | |
184 | frame->control[0] = skb->data[0]; | |
185 | frame->control[1] = 0x00; | |
186 | skb_pull(skb, 1); | |
187 | } | |
188 | } else { | |
189 | if (!(skb->data[0] & LAPB_S)) { | |
190 | /* | |
191 | * I frame - carries NR/NS/PF | |
192 | */ | |
193 | frame->type = LAPB_I; | |
194 | frame->ns = (skb->data[0] >> 1) & 0x07; | |
195 | frame->nr = (skb->data[0] >> 5) & 0x07; | |
196 | frame->pf = skb->data[0] & LAPB_SPF; | |
197 | } else if ((skb->data[0] & LAPB_U) == 1) { | |
198 | /* | |
199 | * S frame - take out PF/NR | |
200 | */ | |
201 | frame->type = skb->data[0] & 0x0F; | |
202 | frame->nr = (skb->data[0] >> 5) & 0x07; | |
203 | frame->pf = skb->data[0] & LAPB_SPF; | |
204 | } else if ((skb->data[0] & LAPB_U) == 3) { | |
205 | /* | |
206 | * U frame - take out PF | |
207 | */ | |
208 | frame->type = skb->data[0] & ~LAPB_SPF; | |
209 | frame->pf = skb->data[0] & LAPB_SPF; | |
210 | } | |
211 | ||
212 | frame->control[0] = skb->data[0]; | |
213 | ||
214 | skb_pull(skb, 1); | |
215 | } | |
216 | ||
217 | return 0; | |
218 | } | |
219 | ||
56d6c3d7 | 220 | /* |
1da177e4 | 221 | * This routine is called when the HDLC layer internally generates a |
56d6c3d7 | 222 | * command or response for the remote machine ( eg. RR, UA etc. ). |
1da177e4 LT |
223 | * Only supervisory or unnumbered frames are processed, FRMRs are handled |
224 | * by lapb_transmit_frmr below. | |
225 | */ | |
226 | void lapb_send_control(struct lapb_cb *lapb, int frametype, | |
227 | int poll_bit, int type) | |
228 | { | |
229 | struct sk_buff *skb; | |
230 | unsigned char *dptr; | |
231 | ||
232 | if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL) | |
233 | return; | |
234 | ||
235 | skb_reserve(skb, LAPB_HEADER_LEN + 1); | |
236 | ||
237 | if (lapb->mode & LAPB_EXTENDED) { | |
238 | if ((frametype & LAPB_U) == LAPB_U) { | |
239 | dptr = skb_put(skb, 1); | |
240 | *dptr = frametype; | |
241 | *dptr |= poll_bit ? LAPB_SPF : 0; | |
242 | } else { | |
243 | dptr = skb_put(skb, 2); | |
244 | dptr[0] = frametype; | |
245 | dptr[1] = (lapb->vr << 1); | |
246 | dptr[1] |= poll_bit ? LAPB_EPF : 0; | |
247 | } | |
248 | } else { | |
249 | dptr = skb_put(skb, 1); | |
250 | *dptr = frametype; | |
251 | *dptr |= poll_bit ? LAPB_SPF : 0; | |
252 | if ((frametype & LAPB_U) == LAPB_S) /* S frames carry NR */ | |
253 | *dptr |= (lapb->vr << 5); | |
254 | } | |
255 | ||
256 | lapb_transmit_buffer(lapb, skb, type); | |
257 | } | |
258 | ||
56d6c3d7 | 259 | /* |
1da177e4 LT |
260 | * This routine generates FRMRs based on information previously stored in |
261 | * the LAPB control block. | |
262 | */ | |
263 | void lapb_transmit_frmr(struct lapb_cb *lapb) | |
264 | { | |
265 | struct sk_buff *skb; | |
266 | unsigned char *dptr; | |
267 | ||
268 | if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL) | |
269 | return; | |
270 | ||
271 | skb_reserve(skb, LAPB_HEADER_LEN + 1); | |
272 | ||
273 | if (lapb->mode & LAPB_EXTENDED) { | |
274 | dptr = skb_put(skb, 6); | |
275 | *dptr++ = LAPB_FRMR; | |
276 | *dptr++ = lapb->frmr_data.control[0]; | |
277 | *dptr++ = lapb->frmr_data.control[1]; | |
278 | *dptr++ = (lapb->vs << 1) & 0xFE; | |
279 | *dptr = (lapb->vr << 1) & 0xFE; | |
280 | if (lapb->frmr_data.cr == LAPB_RESPONSE) | |
281 | *dptr |= 0x01; | |
282 | dptr++; | |
283 | *dptr++ = lapb->frmr_type; | |
284 | ||
0d08df6c | 285 | lapb_dbg(1, "(%p) S%d TX FRMR %5ph\n", |
a508da6c | 286 | lapb->dev, lapb->state, |
0d08df6c | 287 | &skb->data[1]); |
1da177e4 LT |
288 | } else { |
289 | dptr = skb_put(skb, 4); | |
290 | *dptr++ = LAPB_FRMR; | |
291 | *dptr++ = lapb->frmr_data.control[0]; | |
292 | *dptr = (lapb->vs << 1) & 0x0E; | |
293 | *dptr |= (lapb->vr << 5) & 0xE0; | |
294 | if (lapb->frmr_data.cr == LAPB_RESPONSE) | |
295 | *dptr |= 0x10; | |
296 | dptr++; | |
297 | *dptr++ = lapb->frmr_type; | |
298 | ||
0d08df6c AS |
299 | lapb_dbg(1, "(%p) S%d TX FRMR %3ph\n", |
300 | lapb->dev, lapb->state, &skb->data[1]); | |
1da177e4 LT |
301 | } |
302 | ||
303 | lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE); | |
304 | } |