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>
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 <linux/slab.h>
28 #include <net/sock.h>
29 #include <asm/uaccess.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 */
lapb_clear_queues(struct lapb_cb * lapb)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 */
lapb_frames_acked(struct lapb_cb * lapb,unsigned short nr)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) {
61 skb = skb_dequeue(&lapb->ack_queue);
62 kfree_skb(skb);
63 lapb->va = (lapb->va + 1) % modulus;
64 }
65 }
66
lapb_requeue_frames(struct lapb_cb * lapb)67 void lapb_requeue_frames(struct lapb_cb *lapb)
68 {
69 struct sk_buff *skb, *skb_prev = NULL;
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
80 skb_append(skb_prev, skb, &lapb->write_queue);
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 */
lapb_validate_nr(struct lapb_cb * lapb,unsigned short nr)89 int lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr)
90 {
91 unsigned short vc = lapb->va;
92 int modulus;
93
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 }
101
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 */
lapb_decode(struct lapb_cb * lapb,struct sk_buff * skb,struct lapb_frame * frame)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 }
151
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
222 /*
223 * This routine is called when the HDLC layer internally generates a
224 * command or response for the remote machine ( eg. RR, UA etc. ).
225 * Only supervisory or unnumbered frames are processed, FRMRs are handled
226 * by lapb_transmit_frmr below.
227 */
lapb_send_control(struct lapb_cb * lapb,int frametype,int poll_bit,int type)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
261 /*
262 * This routine generates FRMRs based on information previously stored in
263 * the LAPB control block.
264 */
lapb_transmit_frmr(struct lapb_cb * lapb)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 }
313