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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 | ||
16 | #include <linux/errno.h> | |
17 | #include <linux/types.h> | |
18 | #include <linux/socket.h> | |
19 | #include <linux/in.h> | |
20 | #include <linux/kernel.h> | |
1da177e4 LT |
21 | #include <linux/timer.h> |
22 | #include <linux/string.h> | |
23 | #include <linux/sockios.h> | |
24 | #include <linux/net.h> | |
25 | #include <linux/inet.h> | |
26 | #include <linux/skbuff.h> | |
27 | #include <net/sock.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 | #include <net/lapb.h> | |
34 | ||
35 | /* | |
36 | * This routine purges all the queues of frames. | |
37 | */ | |
38 | void lapb_clear_queues(struct lapb_cb *lapb) | |
39 | { | |
40 | skb_queue_purge(&lapb->write_queue); | |
41 | skb_queue_purge(&lapb->ack_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 lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr) | |
50 | { | |
51 | struct sk_buff *skb; | |
52 | int modulus; | |
53 | ||
54 | modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; | |
55 | ||
56 | /* | |
57 | * Remove all the ack-ed frames from the ack queue. | |
58 | */ | |
59 | if (lapb->va != nr) | |
60 | while (skb_peek(&lapb->ack_queue) && lapb->va != nr) { | |
56d6c3d7 | 61 | skb = skb_dequeue(&lapb->ack_queue); |
1da177e4 LT |
62 | kfree_skb(skb); |
63 | lapb->va = (lapb->va + 1) % modulus; | |
64 | } | |
65 | } | |
66 | ||
67 | void lapb_requeue_frames(struct lapb_cb *lapb) | |
68 | { | |
56d6c3d7 | 69 | struct sk_buff *skb, *skb_prev = NULL; |
1da177e4 LT |
70 | |
71 | /* | |
72 | * Requeue all the un-ack-ed frames on the output queue to be picked | |
73 | * up by lapb_kick called from the timer. This arrangement handles the | |
74 | * possibility of an empty output queue. | |
75 | */ | |
76 | while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) { | |
77 | if (!skb_prev) | |
78 | skb_queue_head(&lapb->write_queue, skb); | |
79 | else | |
8728b834 | 80 | skb_append(skb_prev, skb, &lapb->write_queue); |
1da177e4 LT |
81 | skb_prev = skb; |
82 | } | |
83 | } | |
84 | ||
85 | /* | |
86 | * Validate that the value of nr is between va and vs. Return true or | |
87 | * false for testing. | |
88 | */ | |
89 | int lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr) | |
90 | { | |
91 | unsigned short vc = lapb->va; | |
92 | int modulus; | |
56d6c3d7 | 93 | |
1da177e4 LT |
94 | modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; |
95 | ||
96 | while (vc != lapb->vs) { | |
97 | if (nr == vc) | |
98 | return 1; | |
99 | vc = (vc + 1) % modulus; | |
100 | } | |
56d6c3d7 | 101 | |
1da177e4 LT |
102 | return nr == lapb->vs; |
103 | } | |
104 | ||
105 | /* | |
106 | * This routine is the centralised routine for parsing the control | |
107 | * information for the different frame formats. | |
108 | */ | |
109 | int lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb, | |
110 | struct lapb_frame *frame) | |
111 | { | |
112 | frame->type = LAPB_ILLEGAL; | |
113 | ||
114 | #if LAPB_DEBUG > 2 | |
115 | printk(KERN_DEBUG "lapb: (%p) S%d RX %02X %02X %02X\n", | |
116 | lapb->dev, lapb->state, | |
117 | skb->data[0], skb->data[1], skb->data[2]); | |
118 | #endif | |
119 | ||
120 | /* We always need to look at 2 bytes, sometimes we need | |
121 | * to look at 3 and those cases are handled below. | |
122 | */ | |
123 | if (!pskb_may_pull(skb, 2)) | |
124 | return -1; | |
125 | ||
126 | if (lapb->mode & LAPB_MLP) { | |
127 | if (lapb->mode & LAPB_DCE) { | |
128 | if (skb->data[0] == LAPB_ADDR_D) | |
129 | frame->cr = LAPB_COMMAND; | |
130 | if (skb->data[0] == LAPB_ADDR_C) | |
131 | frame->cr = LAPB_RESPONSE; | |
132 | } else { | |
133 | if (skb->data[0] == LAPB_ADDR_C) | |
134 | frame->cr = LAPB_COMMAND; | |
135 | if (skb->data[0] == LAPB_ADDR_D) | |
136 | frame->cr = LAPB_RESPONSE; | |
137 | } | |
138 | } else { | |
139 | if (lapb->mode & LAPB_DCE) { | |
140 | if (skb->data[0] == LAPB_ADDR_B) | |
141 | frame->cr = LAPB_COMMAND; | |
142 | if (skb->data[0] == LAPB_ADDR_A) | |
143 | frame->cr = LAPB_RESPONSE; | |
144 | } else { | |
145 | if (skb->data[0] == LAPB_ADDR_A) | |
146 | frame->cr = LAPB_COMMAND; | |
147 | if (skb->data[0] == LAPB_ADDR_B) | |
148 | frame->cr = LAPB_RESPONSE; | |
149 | } | |
150 | } | |
56d6c3d7 | 151 | |
1da177e4 LT |
152 | skb_pull(skb, 1); |
153 | ||
154 | if (lapb->mode & LAPB_EXTENDED) { | |
155 | if (!(skb->data[0] & LAPB_S)) { | |
156 | if (!pskb_may_pull(skb, 2)) | |
157 | return -1; | |
158 | /* | |
159 | * I frame - carries NR/NS/PF | |
160 | */ | |
161 | frame->type = LAPB_I; | |
162 | frame->ns = (skb->data[0] >> 1) & 0x7F; | |
163 | frame->nr = (skb->data[1] >> 1) & 0x7F; | |
164 | frame->pf = skb->data[1] & LAPB_EPF; | |
165 | frame->control[0] = skb->data[0]; | |
166 | frame->control[1] = skb->data[1]; | |
167 | skb_pull(skb, 2); | |
168 | } else if ((skb->data[0] & LAPB_U) == 1) { | |
169 | if (!pskb_may_pull(skb, 2)) | |
170 | return -1; | |
171 | /* | |
172 | * S frame - take out PF/NR | |
173 | */ | |
174 | frame->type = skb->data[0] & 0x0F; | |
175 | frame->nr = (skb->data[1] >> 1) & 0x7F; | |
176 | frame->pf = skb->data[1] & LAPB_EPF; | |
177 | frame->control[0] = skb->data[0]; | |
178 | frame->control[1] = skb->data[1]; | |
179 | skb_pull(skb, 2); | |
180 | } else if ((skb->data[0] & LAPB_U) == 3) { | |
181 | /* | |
182 | * U frame - take out PF | |
183 | */ | |
184 | frame->type = skb->data[0] & ~LAPB_SPF; | |
185 | frame->pf = skb->data[0] & LAPB_SPF; | |
186 | frame->control[0] = skb->data[0]; | |
187 | frame->control[1] = 0x00; | |
188 | skb_pull(skb, 1); | |
189 | } | |
190 | } else { | |
191 | if (!(skb->data[0] & LAPB_S)) { | |
192 | /* | |
193 | * I frame - carries NR/NS/PF | |
194 | */ | |
195 | frame->type = LAPB_I; | |
196 | frame->ns = (skb->data[0] >> 1) & 0x07; | |
197 | frame->nr = (skb->data[0] >> 5) & 0x07; | |
198 | frame->pf = skb->data[0] & LAPB_SPF; | |
199 | } else if ((skb->data[0] & LAPB_U) == 1) { | |
200 | /* | |
201 | * S frame - take out PF/NR | |
202 | */ | |
203 | frame->type = skb->data[0] & 0x0F; | |
204 | frame->nr = (skb->data[0] >> 5) & 0x07; | |
205 | frame->pf = skb->data[0] & LAPB_SPF; | |
206 | } else if ((skb->data[0] & LAPB_U) == 3) { | |
207 | /* | |
208 | * U frame - take out PF | |
209 | */ | |
210 | frame->type = skb->data[0] & ~LAPB_SPF; | |
211 | frame->pf = skb->data[0] & LAPB_SPF; | |
212 | } | |
213 | ||
214 | frame->control[0] = skb->data[0]; | |
215 | ||
216 | skb_pull(skb, 1); | |
217 | } | |
218 | ||
219 | return 0; | |
220 | } | |
221 | ||
56d6c3d7 | 222 | /* |
1da177e4 | 223 | * This routine is called when the HDLC layer internally generates a |
56d6c3d7 | 224 | * command or response for the remote machine ( eg. RR, UA etc. ). |
1da177e4 LT |
225 | * Only supervisory or unnumbered frames are processed, FRMRs are handled |
226 | * by lapb_transmit_frmr below. | |
227 | */ | |
228 | void lapb_send_control(struct lapb_cb *lapb, int frametype, | |
229 | int poll_bit, int type) | |
230 | { | |
231 | struct sk_buff *skb; | |
232 | unsigned char *dptr; | |
233 | ||
234 | if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL) | |
235 | return; | |
236 | ||
237 | skb_reserve(skb, LAPB_HEADER_LEN + 1); | |
238 | ||
239 | if (lapb->mode & LAPB_EXTENDED) { | |
240 | if ((frametype & LAPB_U) == LAPB_U) { | |
241 | dptr = skb_put(skb, 1); | |
242 | *dptr = frametype; | |
243 | *dptr |= poll_bit ? LAPB_SPF : 0; | |
244 | } else { | |
245 | dptr = skb_put(skb, 2); | |
246 | dptr[0] = frametype; | |
247 | dptr[1] = (lapb->vr << 1); | |
248 | dptr[1] |= poll_bit ? LAPB_EPF : 0; | |
249 | } | |
250 | } else { | |
251 | dptr = skb_put(skb, 1); | |
252 | *dptr = frametype; | |
253 | *dptr |= poll_bit ? LAPB_SPF : 0; | |
254 | if ((frametype & LAPB_U) == LAPB_S) /* S frames carry NR */ | |
255 | *dptr |= (lapb->vr << 5); | |
256 | } | |
257 | ||
258 | lapb_transmit_buffer(lapb, skb, type); | |
259 | } | |
260 | ||
56d6c3d7 | 261 | /* |
1da177e4 LT |
262 | * This routine generates FRMRs based on information previously stored in |
263 | * the LAPB control block. | |
264 | */ | |
265 | void lapb_transmit_frmr(struct lapb_cb *lapb) | |
266 | { | |
267 | struct sk_buff *skb; | |
268 | unsigned char *dptr; | |
269 | ||
270 | if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL) | |
271 | return; | |
272 | ||
273 | skb_reserve(skb, LAPB_HEADER_LEN + 1); | |
274 | ||
275 | if (lapb->mode & LAPB_EXTENDED) { | |
276 | dptr = skb_put(skb, 6); | |
277 | *dptr++ = LAPB_FRMR; | |
278 | *dptr++ = lapb->frmr_data.control[0]; | |
279 | *dptr++ = lapb->frmr_data.control[1]; | |
280 | *dptr++ = (lapb->vs << 1) & 0xFE; | |
281 | *dptr = (lapb->vr << 1) & 0xFE; | |
282 | if (lapb->frmr_data.cr == LAPB_RESPONSE) | |
283 | *dptr |= 0x01; | |
284 | dptr++; | |
285 | *dptr++ = lapb->frmr_type; | |
286 | ||
287 | #if LAPB_DEBUG > 1 | |
288 | printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X %02X %02X\n", | |
289 | lapb->dev, lapb->state, | |
290 | skb->data[1], skb->data[2], skb->data[3], | |
291 | skb->data[4], skb->data[5]); | |
292 | #endif | |
293 | } else { | |
294 | dptr = skb_put(skb, 4); | |
295 | *dptr++ = LAPB_FRMR; | |
296 | *dptr++ = lapb->frmr_data.control[0]; | |
297 | *dptr = (lapb->vs << 1) & 0x0E; | |
298 | *dptr |= (lapb->vr << 5) & 0xE0; | |
299 | if (lapb->frmr_data.cr == LAPB_RESPONSE) | |
300 | *dptr |= 0x10; | |
301 | dptr++; | |
302 | *dptr++ = lapb->frmr_type; | |
303 | ||
304 | #if LAPB_DEBUG > 1 | |
305 | printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X\n", | |
306 | lapb->dev, lapb->state, skb->data[1], | |
307 | skb->data[2], skb->data[3]); | |
308 | #endif | |
309 | } | |
310 | ||
311 | lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE); | |
312 | } |