Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * BSD compression module | |
3 | * | |
4 | * Patched version for ISDN syncPPP written 1997/1998 by Michael Hipp | |
5 | * The whole module is now SKB based. | |
6 | * | |
7 | */ | |
8 | ||
9 | /* | |
10 | * Update: The Berkeley copyright was changed, and the change | |
11 | * is retroactive to all "true" BSD software (ie everything | |
12 | * from UCB as opposed to other peoples code that just carried | |
13 | * the same license). The new copyright doesn't clash with the | |
14 | * GPL, so the module-only restriction has been removed.. | |
15 | */ | |
16 | ||
17 | /* | |
18 | * Original copyright notice: | |
19 | * | |
20 | * Copyright (c) 1985, 1986 The Regents of the University of California. | |
21 | * All rights reserved. | |
22 | * | |
23 | * This code is derived from software contributed to Berkeley by | |
24 | * James A. Woods, derived from original work by Spencer Thomas | |
25 | * and Joseph Orost. | |
26 | * | |
27 | * Redistribution and use in source and binary forms, with or without | |
28 | * modification, are permitted provided that the following conditions | |
29 | * are met: | |
30 | * 1. Redistributions of source code must retain the above copyright | |
31 | * notice, this list of conditions and the following disclaimer. | |
32 | * 2. Redistributions in binary form must reproduce the above copyright | |
33 | * notice, this list of conditions and the following disclaimer in the | |
34 | * documentation and/or other materials provided with the distribution. | |
35 | * 3. All advertising materials mentioning features or use of this software | |
36 | * must display the following acknowledgement: | |
37 | * This product includes software developed by the University of | |
38 | * California, Berkeley and its contributors. | |
39 | * 4. Neither the name of the University nor the names of its contributors | |
40 | * may be used to endorse or promote products derived from this software | |
41 | * without specific prior written permission. | |
42 | * | |
43 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
44 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
45 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
46 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
47 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
48 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
49 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
50 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
51 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
52 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
53 | * SUCH DAMAGE. | |
54 | */ | |
55 | ||
56 | #include <linux/module.h> | |
57 | #include <linux/init.h> | |
58 | #include <linux/kernel.h> | |
59 | #include <linux/sched.h> | |
60 | #include <linux/types.h> | |
61 | #include <linux/fcntl.h> | |
62 | #include <linux/interrupt.h> | |
63 | #include <linux/ptrace.h> | |
64 | #include <linux/ioport.h> | |
65 | #include <linux/in.h> | |
66 | #include <linux/slab.h> | |
67 | #include <linux/tty.h> | |
68 | #include <linux/errno.h> | |
69 | #include <linux/string.h> /* used in new tty drivers */ | |
70 | #include <linux/signal.h> /* used in new tty drivers */ | |
71 | #include <linux/bitops.h> | |
72 | ||
73 | #include <asm/system.h> | |
74 | #include <asm/byteorder.h> | |
75 | #include <asm/types.h> | |
76 | ||
77 | #include <linux/if.h> | |
78 | ||
79 | #include <linux/if_ether.h> | |
80 | #include <linux/netdevice.h> | |
81 | #include <linux/skbuff.h> | |
82 | #include <linux/inet.h> | |
83 | #include <linux/ioctl.h> | |
84 | #include <linux/vmalloc.h> | |
85 | ||
86 | #include <linux/ppp_defs.h> | |
87 | ||
88 | #include <linux/isdn.h> | |
89 | #include <linux/isdn_ppp.h> | |
90 | #include <linux/ip.h> | |
91 | #include <linux/tcp.h> | |
92 | #include <linux/if_arp.h> | |
93 | #include <linux/ppp-comp.h> | |
94 | ||
95 | #include "isdn_ppp.h" | |
96 | ||
97 | MODULE_DESCRIPTION("ISDN4Linux: BSD Compression for PPP over ISDN"); | |
98 | MODULE_LICENSE("Dual BSD/GPL"); | |
99 | ||
100 | #define BSD_VERSION(x) ((x) >> 5) | |
101 | #define BSD_NBITS(x) ((x) & 0x1F) | |
102 | ||
103 | #define BSD_CURRENT_VERSION 1 | |
104 | ||
105 | #define DEBUG 1 | |
106 | ||
107 | /* | |
108 | * A dictionary for doing BSD compress. | |
109 | */ | |
110 | ||
111 | struct bsd_dict { | |
112 | u32 fcode; | |
113 | u16 codem1; /* output of hash table -1 */ | |
114 | u16 cptr; /* map code to hash table entry */ | |
115 | }; | |
116 | ||
117 | struct bsd_db { | |
118 | int totlen; /* length of this structure */ | |
119 | unsigned int hsize; /* size of the hash table */ | |
120 | unsigned char hshift; /* used in hash function */ | |
121 | unsigned char n_bits; /* current bits/code */ | |
122 | unsigned char maxbits; /* maximum bits/code */ | |
123 | unsigned char debug; /* non-zero if debug desired */ | |
124 | unsigned char unit; /* ppp unit number */ | |
125 | u16 seqno; /* sequence # of next packet */ | |
126 | unsigned int mru; /* size of receive (decompress) bufr */ | |
127 | unsigned int maxmaxcode; /* largest valid code */ | |
128 | unsigned int max_ent; /* largest code in use */ | |
129 | unsigned int in_count; /* uncompressed bytes, aged */ | |
130 | unsigned int bytes_out; /* compressed bytes, aged */ | |
131 | unsigned int ratio; /* recent compression ratio */ | |
132 | unsigned int checkpoint; /* when to next check the ratio */ | |
133 | unsigned int clear_count; /* times dictionary cleared */ | |
134 | unsigned int incomp_count; /* incompressible packets */ | |
135 | unsigned int incomp_bytes; /* incompressible bytes */ | |
136 | unsigned int uncomp_count; /* uncompressed packets */ | |
137 | unsigned int uncomp_bytes; /* uncompressed bytes */ | |
138 | unsigned int comp_count; /* compressed packets */ | |
139 | unsigned int comp_bytes; /* compressed bytes */ | |
140 | unsigned short *lens; /* array of lengths of codes */ | |
141 | struct bsd_dict *dict; /* dictionary */ | |
142 | int xmit; | |
143 | }; | |
144 | ||
145 | #define BSD_OVHD 2 /* BSD compress overhead/packet */ | |
146 | #define MIN_BSD_BITS 9 | |
147 | #define BSD_INIT_BITS MIN_BSD_BITS | |
148 | #define MAX_BSD_BITS 15 | |
149 | ||
150 | /* | |
151 | * the next two codes should not be changed lightly, as they must not | |
152 | * lie within the contiguous general code space. | |
153 | */ | |
154 | #define CLEAR 256 /* table clear output code */ | |
155 | #define FIRST 257 /* first free entry */ | |
156 | #define LAST 255 | |
157 | ||
158 | #define MAXCODE(b) ((1 << (b)) - 1) | |
159 | #define BADCODEM1 MAXCODE(MAX_BSD_BITS); | |
160 | ||
161 | #define BSD_HASH(prefix,suffix,hshift) ((((unsigned long)(suffix))<<(hshift)) \ | |
162 | ^ (unsigned long)(prefix)) | |
163 | #define BSD_KEY(prefix,suffix) ((((unsigned long)(suffix)) << 16) \ | |
164 | + (unsigned long)(prefix)) | |
165 | ||
166 | #define CHECK_GAP 10000 /* Ratio check interval */ | |
167 | ||
168 | #define RATIO_SCALE_LOG 8 | |
169 | #define RATIO_SCALE (1<<RATIO_SCALE_LOG) | |
170 | #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) | |
171 | ||
172 | /* | |
173 | * clear the dictionary | |
174 | */ | |
175 | ||
176 | static void bsd_clear(struct bsd_db *db) | |
177 | { | |
178 | db->clear_count++; | |
179 | db->max_ent = FIRST-1; | |
180 | db->n_bits = BSD_INIT_BITS; | |
181 | db->bytes_out = 0; | |
182 | db->in_count = 0; | |
183 | db->incomp_count = 0; | |
184 | db->ratio = 0; | |
185 | db->checkpoint = CHECK_GAP; | |
186 | } | |
187 | ||
188 | /* | |
189 | * If the dictionary is full, then see if it is time to reset it. | |
190 | * | |
191 | * Compute the compression ratio using fixed-point arithmetic | |
192 | * with 8 fractional bits. | |
193 | * | |
194 | * Since we have an infinite stream instead of a single file, | |
195 | * watch only the local compression ratio. | |
196 | * | |
197 | * Since both peers must reset the dictionary at the same time even in | |
198 | * the absence of CLEAR codes (while packets are incompressible), they | |
199 | * must compute the same ratio. | |
200 | */ | |
201 | static int bsd_check (struct bsd_db *db) /* 1=output CLEAR */ | |
202 | { | |
203 | unsigned int new_ratio; | |
204 | ||
205 | if (db->in_count >= db->checkpoint) | |
206 | { | |
207 | /* age the ratio by limiting the size of the counts */ | |
208 | if (db->in_count >= RATIO_MAX || db->bytes_out >= RATIO_MAX) | |
209 | { | |
210 | db->in_count -= (db->in_count >> 2); | |
211 | db->bytes_out -= (db->bytes_out >> 2); | |
212 | } | |
213 | ||
214 | db->checkpoint = db->in_count + CHECK_GAP; | |
215 | ||
216 | if (db->max_ent >= db->maxmaxcode) | |
217 | { | |
218 | /* Reset the dictionary only if the ratio is worse, | |
219 | * or if it looks as if it has been poisoned | |
220 | * by incompressible data. | |
221 | * | |
222 | * This does not overflow, because | |
223 | * db->in_count <= RATIO_MAX. | |
224 | */ | |
225 | ||
226 | new_ratio = db->in_count << RATIO_SCALE_LOG; | |
227 | if (db->bytes_out != 0) | |
228 | { | |
229 | new_ratio /= db->bytes_out; | |
230 | } | |
231 | ||
232 | if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) | |
233 | { | |
234 | bsd_clear (db); | |
235 | return 1; | |
236 | } | |
237 | db->ratio = new_ratio; | |
238 | } | |
239 | } | |
240 | return 0; | |
241 | } | |
242 | ||
243 | /* | |
244 | * Return statistics. | |
245 | */ | |
246 | ||
247 | static void bsd_stats (void *state, struct compstat *stats) | |
248 | { | |
249 | struct bsd_db *db = (struct bsd_db *) state; | |
250 | ||
251 | stats->unc_bytes = db->uncomp_bytes; | |
252 | stats->unc_packets = db->uncomp_count; | |
253 | stats->comp_bytes = db->comp_bytes; | |
254 | stats->comp_packets = db->comp_count; | |
255 | stats->inc_bytes = db->incomp_bytes; | |
256 | stats->inc_packets = db->incomp_count; | |
257 | stats->in_count = db->in_count; | |
258 | stats->bytes_out = db->bytes_out; | |
259 | } | |
260 | ||
261 | /* | |
262 | * Reset state, as on a CCP ResetReq. | |
263 | */ | |
264 | static void bsd_reset (void *state,unsigned char code, unsigned char id, | |
265 | unsigned char *data, unsigned len, | |
266 | struct isdn_ppp_resetparams *rsparm) | |
267 | { | |
268 | struct bsd_db *db = (struct bsd_db *) state; | |
269 | ||
270 | bsd_clear(db); | |
271 | db->seqno = 0; | |
272 | db->clear_count = 0; | |
273 | } | |
274 | ||
275 | /* | |
276 | * Release the compression structure | |
277 | */ | |
278 | static void bsd_free (void *state) | |
279 | { | |
280 | struct bsd_db *db = (struct bsd_db *) state; | |
281 | ||
282 | if (db) { | |
283 | /* | |
284 | * Release the dictionary | |
285 | */ | |
f9101210 JJ |
286 | vfree(db->dict); |
287 | db->dict = NULL; | |
1da177e4 LT |
288 | |
289 | /* | |
290 | * Release the string buffer | |
291 | */ | |
f9101210 JJ |
292 | vfree(db->lens); |
293 | db->lens = NULL; | |
1da177e4 LT |
294 | |
295 | /* | |
296 | * Finally release the structure itself. | |
297 | */ | |
f9101210 | 298 | kfree(db); |
1da177e4 LT |
299 | } |
300 | } | |
301 | ||
302 | ||
303 | /* | |
304 | * Allocate space for a (de) compressor. | |
305 | */ | |
306 | static void *bsd_alloc (struct isdn_ppp_comp_data *data) | |
307 | { | |
308 | int bits; | |
309 | unsigned int hsize, hshift, maxmaxcode; | |
310 | struct bsd_db *db; | |
311 | int decomp; | |
312 | ||
313 | static unsigned int htab[][2] = { | |
314 | { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } , | |
315 | { 9001 , 5 } , { 18013 , 6 } , { 35023 , 7 } , { 69001 , 8 } | |
316 | }; | |
317 | ||
318 | if (data->optlen != 1 || data->num != CI_BSD_COMPRESS | |
319 | || BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION) | |
320 | return NULL; | |
321 | ||
322 | bits = BSD_NBITS(data->options[0]); | |
323 | ||
324 | if(bits < 9 || bits > 15) | |
325 | return NULL; | |
326 | ||
327 | hsize = htab[bits-9][0]; | |
328 | hshift = htab[bits-9][1]; | |
329 | ||
330 | /* | |
331 | * Allocate the main control structure for this instance. | |
332 | */ | |
333 | maxmaxcode = MAXCODE(bits); | |
334 | db = (struct bsd_db *) kmalloc (sizeof (struct bsd_db),GFP_KERNEL); | |
335 | if (!db) | |
336 | return NULL; | |
337 | ||
338 | memset (db, 0, sizeof(struct bsd_db)); | |
339 | ||
340 | db->xmit = data->flags & IPPP_COMP_FLAG_XMIT; | |
341 | decomp = db->xmit ? 0 : 1; | |
342 | ||
343 | /* | |
344 | * Allocate space for the dictionary. This may be more than one page in | |
345 | * length. | |
346 | */ | |
347 | db->dict = (struct bsd_dict *) vmalloc (hsize * sizeof (struct bsd_dict)); | |
348 | if (!db->dict) { | |
349 | bsd_free (db); | |
350 | return NULL; | |
351 | } | |
352 | ||
353 | /* | |
354 | * If this is the compression buffer then there is no length data. | |
355 | * For decompression, the length information is needed as well. | |
356 | */ | |
357 | if (!decomp) | |
358 | db->lens = NULL; | |
359 | else { | |
360 | db->lens = (unsigned short *) vmalloc ((maxmaxcode + 1) * | |
361 | sizeof (db->lens[0])); | |
362 | if (!db->lens) { | |
363 | bsd_free (db); | |
364 | return (NULL); | |
365 | } | |
366 | } | |
367 | ||
368 | /* | |
369 | * Initialize the data information for the compression code | |
370 | */ | |
371 | db->totlen = sizeof (struct bsd_db) + (sizeof (struct bsd_dict) * hsize); | |
372 | db->hsize = hsize; | |
373 | db->hshift = hshift; | |
374 | db->maxmaxcode = maxmaxcode; | |
375 | db->maxbits = bits; | |
376 | ||
377 | return (void *) db; | |
378 | } | |
379 | ||
380 | /* | |
381 | * Initialize the database. | |
382 | */ | |
383 | static int bsd_init (void *state, struct isdn_ppp_comp_data *data, int unit, int debug) | |
384 | { | |
385 | struct bsd_db *db = state; | |
386 | int indx; | |
387 | int decomp; | |
388 | ||
389 | if(!state || !data) { | |
390 | printk(KERN_ERR "isdn_bsd_init: [%d] ERR, state %lx data %lx\n",unit,(long)state,(long)data); | |
391 | return 0; | |
392 | } | |
393 | ||
394 | decomp = db->xmit ? 0 : 1; | |
395 | ||
396 | if (data->optlen != 1 || data->num != CI_BSD_COMPRESS | |
397 | || (BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION) | |
398 | || (BSD_NBITS(data->options[0]) != db->maxbits) | |
399 | || (decomp && db->lens == NULL)) { | |
400 | printk(KERN_ERR "isdn_bsd: %d %d %d %d %lx\n",data->optlen,data->num,data->options[0],decomp,(unsigned long)db->lens); | |
401 | return 0; | |
402 | } | |
403 | ||
404 | if (decomp) | |
405 | for(indx=LAST;indx>=0;indx--) | |
406 | db->lens[indx] = 1; | |
407 | ||
408 | indx = db->hsize; | |
409 | while (indx-- != 0) { | |
410 | db->dict[indx].codem1 = BADCODEM1; | |
411 | db->dict[indx].cptr = 0; | |
412 | } | |
413 | ||
414 | db->unit = unit; | |
415 | db->mru = 0; | |
416 | ||
417 | db->debug = 1; | |
418 | ||
419 | bsd_reset(db,0,0,NULL,0,NULL); | |
420 | ||
421 | return 1; | |
422 | } | |
423 | ||
424 | /* | |
425 | * Obtain pointers to the various structures in the compression tables | |
426 | */ | |
427 | ||
428 | #define dict_ptrx(p,idx) &(p->dict[idx]) | |
429 | #define lens_ptrx(p,idx) &(p->lens[idx]) | |
430 | ||
431 | #ifdef DEBUG | |
432 | static unsigned short *lens_ptr(struct bsd_db *db, int idx) | |
433 | { | |
434 | if ((unsigned int) idx > (unsigned int) db->maxmaxcode) { | |
435 | printk (KERN_DEBUG "<9>ppp: lens_ptr(%d) > max\n", idx); | |
436 | idx = 0; | |
437 | } | |
438 | return lens_ptrx (db, idx); | |
439 | } | |
440 | ||
441 | static struct bsd_dict *dict_ptr(struct bsd_db *db, int idx) | |
442 | { | |
443 | if ((unsigned int) idx >= (unsigned int) db->hsize) { | |
444 | printk (KERN_DEBUG "<9>ppp: dict_ptr(%d) > max\n", idx); | |
445 | idx = 0; | |
446 | } | |
447 | return dict_ptrx (db, idx); | |
448 | } | |
449 | ||
450 | #else | |
451 | #define lens_ptr(db,idx) lens_ptrx(db,idx) | |
452 | #define dict_ptr(db,idx) dict_ptrx(db,idx) | |
453 | #endif | |
454 | ||
455 | /* | |
456 | * compress a packet | |
457 | */ | |
458 | static int bsd_compress (void *state, struct sk_buff *skb_in, struct sk_buff *skb_out,int proto) | |
459 | { | |
460 | struct bsd_db *db; | |
461 | int hshift; | |
462 | unsigned int max_ent; | |
463 | unsigned int n_bits; | |
464 | unsigned int bitno; | |
465 | unsigned long accm; | |
466 | int ent; | |
467 | unsigned long fcode; | |
468 | struct bsd_dict *dictp; | |
469 | unsigned char c; | |
470 | int hval,disp,ilen,mxcode; | |
471 | unsigned char *rptr = skb_in->data; | |
472 | int isize = skb_in->len; | |
473 | ||
474 | #define OUTPUT(ent) \ | |
475 | { \ | |
476 | bitno -= n_bits; \ | |
477 | accm |= ((ent) << bitno); \ | |
478 | do { \ | |
479 | if(skb_out && skb_tailroom(skb_out) > 0) \ | |
480 | *(skb_put(skb_out,1)) = (unsigned char) (accm>>24); \ | |
481 | accm <<= 8; \ | |
482 | bitno += 8; \ | |
483 | } while (bitno <= 24); \ | |
484 | } | |
485 | ||
486 | /* | |
487 | * If the protocol is not in the range we're interested in, | |
488 | * just return without compressing the packet. If it is, | |
489 | * the protocol becomes the first byte to compress. | |
490 | */ | |
491 | printk(KERN_DEBUG "bsd_compress called with %x\n",proto); | |
492 | ||
493 | ent = proto; | |
494 | if (proto < 0x21 || proto > 0xf9 || !(proto & 0x1) ) | |
495 | return 0; | |
496 | ||
497 | db = (struct bsd_db *) state; | |
498 | hshift = db->hshift; | |
499 | max_ent = db->max_ent; | |
500 | n_bits = db->n_bits; | |
501 | bitno = 32; | |
502 | accm = 0; | |
503 | mxcode = MAXCODE (n_bits); | |
504 | ||
505 | /* This is the PPP header information */ | |
506 | if(skb_out && skb_tailroom(skb_out) >= 2) { | |
507 | char *v = skb_put(skb_out,2); | |
508 | /* we only push our own data on the header, | |
509 | AC,PC and protos is pushed by caller */ | |
510 | v[0] = db->seqno >> 8; | |
511 | v[1] = db->seqno; | |
512 | } | |
513 | ||
514 | ilen = ++isize; /* This is off by one, but that is what is in draft! */ | |
515 | ||
516 | while (--ilen > 0) { | |
517 | c = *rptr++; | |
518 | fcode = BSD_KEY (ent, c); | |
519 | hval = BSD_HASH (ent, c, hshift); | |
520 | dictp = dict_ptr (db, hval); | |
521 | ||
522 | /* Validate and then check the entry. */ | |
523 | if (dictp->codem1 >= max_ent) | |
524 | goto nomatch; | |
525 | ||
526 | if (dictp->fcode == fcode) { | |
527 | ent = dictp->codem1 + 1; | |
528 | continue; /* found (prefix,suffix) */ | |
529 | } | |
530 | ||
531 | /* continue probing until a match or invalid entry */ | |
532 | disp = (hval == 0) ? 1 : hval; | |
533 | ||
534 | do { | |
535 | hval += disp; | |
536 | if (hval >= db->hsize) | |
537 | hval -= db->hsize; | |
538 | dictp = dict_ptr (db, hval); | |
539 | if (dictp->codem1 >= max_ent) | |
540 | goto nomatch; | |
541 | } while (dictp->fcode != fcode); | |
542 | ||
543 | ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */ | |
544 | continue; | |
545 | ||
546 | nomatch: | |
547 | OUTPUT(ent); /* output the prefix */ | |
548 | ||
549 | /* code -> hashtable */ | |
550 | if (max_ent < db->maxmaxcode) { | |
551 | struct bsd_dict *dictp2; | |
552 | struct bsd_dict *dictp3; | |
553 | int indx; | |
554 | ||
555 | /* expand code size if needed */ | |
556 | if (max_ent >= mxcode) { | |
557 | db->n_bits = ++n_bits; | |
558 | mxcode = MAXCODE (n_bits); | |
559 | } | |
560 | ||
561 | /* | |
562 | * Invalidate old hash table entry using | |
563 | * this code, and then take it over. | |
564 | */ | |
565 | dictp2 = dict_ptr (db, max_ent + 1); | |
566 | indx = dictp2->cptr; | |
567 | dictp3 = dict_ptr (db, indx); | |
568 | ||
569 | if (dictp3->codem1 == max_ent) | |
570 | dictp3->codem1 = BADCODEM1; | |
571 | ||
572 | dictp2->cptr = hval; | |
573 | dictp->codem1 = max_ent; | |
574 | dictp->fcode = fcode; | |
575 | db->max_ent = ++max_ent; | |
576 | ||
577 | if (db->lens) { | |
578 | unsigned short *len1 = lens_ptr (db, max_ent); | |
579 | unsigned short *len2 = lens_ptr (db, ent); | |
580 | *len1 = *len2 + 1; | |
581 | } | |
582 | } | |
583 | ent = c; | |
584 | } | |
585 | ||
586 | OUTPUT(ent); /* output the last code */ | |
587 | ||
588 | if(skb_out) | |
589 | db->bytes_out += skb_out->len; /* Do not count bytes from here */ | |
590 | db->uncomp_bytes += isize; | |
591 | db->in_count += isize; | |
592 | ++db->uncomp_count; | |
593 | ++db->seqno; | |
594 | ||
595 | if (bitno < 32) | |
596 | ++db->bytes_out; /* must be set before calling bsd_check */ | |
597 | ||
598 | /* | |
599 | * Generate the clear command if needed | |
600 | */ | |
601 | ||
602 | if (bsd_check(db)) | |
603 | OUTPUT (CLEAR); | |
604 | ||
605 | /* | |
606 | * Pad dribble bits of last code with ones. | |
607 | * Do not emit a completely useless byte of ones. | |
608 | */ | |
609 | if (bitno < 32 && skb_out && skb_tailroom(skb_out) > 0) | |
610 | *(skb_put(skb_out,1)) = (unsigned char) ((accm | (0xff << (bitno-8))) >> 24); | |
611 | ||
612 | /* | |
613 | * Increase code size if we would have without the packet | |
614 | * boundary because the decompressor will do so. | |
615 | */ | |
616 | if (max_ent >= mxcode && max_ent < db->maxmaxcode) | |
617 | db->n_bits++; | |
618 | ||
619 | /* If output length is too large then this is an incompressible frame. */ | |
620 | if (!skb_out || (skb_out && skb_out->len >= skb_in->len) ) { | |
621 | ++db->incomp_count; | |
622 | db->incomp_bytes += isize; | |
623 | return 0; | |
624 | } | |
625 | ||
626 | /* Count the number of compressed frames */ | |
627 | ++db->comp_count; | |
628 | db->comp_bytes += skb_out->len; | |
629 | return skb_out->len; | |
630 | ||
631 | #undef OUTPUT | |
632 | } | |
633 | ||
634 | /* | |
635 | * Update the "BSD Compress" dictionary on the receiver for | |
636 | * incompressible data by pretending to compress the incoming data. | |
637 | */ | |
638 | static void bsd_incomp (void *state, struct sk_buff *skb_in,int proto) | |
639 | { | |
640 | bsd_compress (state, skb_in, NULL, proto); | |
641 | } | |
642 | ||
643 | /* | |
644 | * Decompress "BSD Compress". | |
645 | */ | |
646 | static int bsd_decompress (void *state, struct sk_buff *skb_in, struct sk_buff *skb_out, | |
647 | struct isdn_ppp_resetparams *rsparm) | |
648 | { | |
649 | struct bsd_db *db; | |
650 | unsigned int max_ent; | |
651 | unsigned long accm; | |
652 | unsigned int bitno; /* 1st valid bit in accm */ | |
653 | unsigned int n_bits; | |
654 | unsigned int tgtbitno; /* bitno when we have a code */ | |
655 | struct bsd_dict *dictp; | |
656 | int seq; | |
657 | unsigned int incode; | |
658 | unsigned int oldcode; | |
659 | unsigned int finchar; | |
660 | unsigned char *p,*ibuf; | |
661 | int ilen; | |
662 | int codelen; | |
663 | int extra; | |
664 | ||
665 | db = (struct bsd_db *) state; | |
666 | max_ent = db->max_ent; | |
667 | accm = 0; | |
668 | bitno = 32; /* 1st valid bit in accm */ | |
669 | n_bits = db->n_bits; | |
670 | tgtbitno = 32 - n_bits; /* bitno when we have a code */ | |
671 | ||
672 | printk(KERN_DEBUG "bsd_decompress called\n"); | |
673 | ||
674 | if(!skb_in || !skb_out) { | |
675 | printk(KERN_ERR "bsd_decompress called with NULL parameter\n"); | |
676 | return DECOMP_ERROR; | |
677 | } | |
678 | ||
679 | /* | |
680 | * Get the sequence number. | |
681 | */ | |
682 | if( (p = skb_pull(skb_in,2)) == NULL) { | |
683 | return DECOMP_ERROR; | |
684 | } | |
685 | p-=2; | |
686 | seq = (p[0] << 8) + p[1]; | |
687 | ilen = skb_in->len; | |
688 | ibuf = skb_in->data; | |
689 | ||
690 | /* | |
691 | * Check the sequence number and give up if it differs from | |
692 | * the value we're expecting. | |
693 | */ | |
694 | if (seq != db->seqno) { | |
695 | if (db->debug) { | |
696 | printk(KERN_DEBUG "bsd_decomp%d: bad sequence # %d, expected %d\n", | |
697 | db->unit, seq, db->seqno - 1); | |
698 | } | |
699 | return DECOMP_ERROR; | |
700 | } | |
701 | ||
702 | ++db->seqno; | |
703 | db->bytes_out += ilen; | |
704 | ||
705 | if(skb_tailroom(skb_out) > 0) | |
706 | *(skb_put(skb_out,1)) = 0; | |
707 | else | |
708 | return DECOMP_ERR_NOMEM; | |
709 | ||
710 | oldcode = CLEAR; | |
711 | ||
712 | /* | |
713 | * Keep the checkpoint correctly so that incompressible packets | |
714 | * clear the dictionary at the proper times. | |
715 | */ | |
716 | ||
717 | for (;;) { | |
718 | if (ilen-- <= 0) { | |
719 | db->in_count += (skb_out->len - 1); /* don't count the header */ | |
720 | break; | |
721 | } | |
722 | ||
723 | /* | |
724 | * Accumulate bytes until we have a complete code. | |
725 | * Then get the next code, relying on the 32-bit, | |
726 | * unsigned accm to mask the result. | |
727 | */ | |
728 | ||
729 | bitno -= 8; | |
730 | accm |= *ibuf++ << bitno; | |
731 | if (tgtbitno < bitno) | |
732 | continue; | |
733 | ||
734 | incode = accm >> tgtbitno; | |
735 | accm <<= n_bits; | |
736 | bitno += n_bits; | |
737 | ||
738 | /* | |
739 | * The dictionary must only be cleared at the end of a packet. | |
740 | */ | |
741 | ||
742 | if (incode == CLEAR) { | |
743 | if (ilen > 0) { | |
744 | if (db->debug) | |
745 | printk(KERN_DEBUG "bsd_decomp%d: bad CLEAR\n", db->unit); | |
746 | return DECOMP_FATALERROR; /* probably a bug */ | |
747 | } | |
748 | bsd_clear(db); | |
749 | break; | |
750 | } | |
751 | ||
752 | if ((incode > max_ent + 2) || (incode > db->maxmaxcode) | |
753 | || (incode > max_ent && oldcode == CLEAR)) { | |
754 | if (db->debug) { | |
755 | printk(KERN_DEBUG "bsd_decomp%d: bad code 0x%x oldcode=0x%x ", | |
756 | db->unit, incode, oldcode); | |
757 | printk(KERN_DEBUG "max_ent=0x%x skb->Len=%d seqno=%d\n", | |
758 | max_ent, skb_out->len, db->seqno); | |
759 | } | |
760 | return DECOMP_FATALERROR; /* probably a bug */ | |
761 | } | |
762 | ||
763 | /* Special case for KwKwK string. */ | |
764 | if (incode > max_ent) { | |
765 | finchar = oldcode; | |
766 | extra = 1; | |
767 | } else { | |
768 | finchar = incode; | |
769 | extra = 0; | |
770 | } | |
771 | ||
772 | codelen = *(lens_ptr (db, finchar)); | |
773 | if( skb_tailroom(skb_out) < codelen + extra) { | |
774 | if (db->debug) { | |
775 | printk(KERN_DEBUG "bsd_decomp%d: ran out of mru\n", db->unit); | |
776 | #ifdef DEBUG | |
777 | printk(KERN_DEBUG " len=%d, finchar=0x%x, codelen=%d,skblen=%d\n", | |
778 | ilen, finchar, codelen, skb_out->len); | |
779 | #endif | |
780 | } | |
781 | return DECOMP_FATALERROR; | |
782 | } | |
783 | ||
784 | /* | |
785 | * Decode this code and install it in the decompressed buffer. | |
786 | */ | |
787 | ||
788 | p = skb_put(skb_out,codelen); | |
789 | p += codelen; | |
790 | while (finchar > LAST) { | |
791 | struct bsd_dict *dictp2 = dict_ptr (db, finchar); | |
792 | ||
793 | dictp = dict_ptr (db, dictp2->cptr); | |
794 | ||
795 | #ifdef DEBUG | |
796 | if (--codelen <= 0 || dictp->codem1 != finchar-1) { | |
797 | if (codelen <= 0) { | |
798 | printk(KERN_ERR "bsd_decomp%d: fell off end of chain ", db->unit); | |
799 | printk(KERN_ERR "0x%x at 0x%x by 0x%x, max_ent=0x%x\n", incode, finchar, dictp2->cptr, max_ent); | |
800 | } else { | |
801 | if (dictp->codem1 != finchar-1) { | |
802 | printk(KERN_ERR "bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",db->unit, incode, finchar); | |
803 | printk(KERN_ERR "oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, dictp2->cptr, dictp->codem1); | |
804 | } | |
805 | } | |
806 | return DECOMP_FATALERROR; | |
807 | } | |
808 | #endif | |
809 | ||
810 | { | |
811 | u32 fcode = dictp->fcode; | |
812 | *--p = (fcode >> 16) & 0xff; | |
813 | finchar = fcode & 0xffff; | |
814 | } | |
815 | } | |
816 | *--p = finchar; | |
817 | ||
818 | #ifdef DEBUG | |
819 | if (--codelen != 0) | |
820 | printk(KERN_ERR "bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", db->unit, codelen, incode, max_ent); | |
821 | #endif | |
822 | ||
823 | if (extra) /* the KwKwK case again */ | |
824 | *(skb_put(skb_out,1)) = finchar; | |
825 | ||
826 | /* | |
827 | * If not first code in a packet, and | |
828 | * if not out of code space, then allocate a new code. | |
829 | * | |
830 | * Keep the hash table correct so it can be used | |
831 | * with uncompressed packets. | |
832 | */ | |
833 | if (oldcode != CLEAR && max_ent < db->maxmaxcode) { | |
834 | struct bsd_dict *dictp2, *dictp3; | |
835 | u16 *lens1, *lens2; | |
836 | unsigned long fcode; | |
837 | int hval, disp, indx; | |
838 | ||
839 | fcode = BSD_KEY(oldcode,finchar); | |
840 | hval = BSD_HASH(oldcode,finchar,db->hshift); | |
841 | dictp = dict_ptr (db, hval); | |
842 | ||
843 | /* look for a free hash table entry */ | |
844 | if (dictp->codem1 < max_ent) { | |
845 | disp = (hval == 0) ? 1 : hval; | |
846 | do { | |
847 | hval += disp; | |
848 | if (hval >= db->hsize) | |
849 | hval -= db->hsize; | |
850 | dictp = dict_ptr (db, hval); | |
851 | } while (dictp->codem1 < max_ent); | |
852 | } | |
853 | ||
854 | /* | |
855 | * Invalidate previous hash table entry | |
856 | * assigned this code, and then take it over | |
857 | */ | |
858 | ||
859 | dictp2 = dict_ptr (db, max_ent + 1); | |
860 | indx = dictp2->cptr; | |
861 | dictp3 = dict_ptr (db, indx); | |
862 | ||
863 | if (dictp3->codem1 == max_ent) | |
864 | dictp3->codem1 = BADCODEM1; | |
865 | ||
866 | dictp2->cptr = hval; | |
867 | dictp->codem1 = max_ent; | |
868 | dictp->fcode = fcode; | |
869 | db->max_ent = ++max_ent; | |
870 | ||
871 | /* Update the length of this string. */ | |
872 | lens1 = lens_ptr (db, max_ent); | |
873 | lens2 = lens_ptr (db, oldcode); | |
874 | *lens1 = *lens2 + 1; | |
875 | ||
876 | /* Expand code size if needed. */ | |
877 | if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) { | |
878 | db->n_bits = ++n_bits; | |
879 | tgtbitno = 32-n_bits; | |
880 | } | |
881 | } | |
882 | oldcode = incode; | |
883 | } | |
884 | ||
885 | ++db->comp_count; | |
886 | ++db->uncomp_count; | |
887 | db->comp_bytes += skb_in->len - BSD_OVHD; | |
888 | db->uncomp_bytes += skb_out->len; | |
889 | ||
890 | if (bsd_check(db)) { | |
891 | if (db->debug) | |
892 | printk(KERN_DEBUG "bsd_decomp%d: peer should have cleared dictionary on %d\n", | |
893 | db->unit, db->seqno - 1); | |
894 | } | |
895 | return skb_out->len; | |
896 | } | |
897 | ||
898 | /************************************************************* | |
899 | * Table of addresses for the BSD compression module | |
900 | *************************************************************/ | |
901 | ||
902 | static struct isdn_ppp_compressor ippp_bsd_compress = { | |
903 | .owner = THIS_MODULE, | |
904 | .num = CI_BSD_COMPRESS, | |
905 | .alloc = bsd_alloc, | |
906 | .free = bsd_free, | |
907 | .init = bsd_init, | |
908 | .reset = bsd_reset, | |
909 | .compress = bsd_compress, | |
910 | .decompress = bsd_decompress, | |
911 | .incomp = bsd_incomp, | |
912 | .stat = bsd_stats, | |
913 | }; | |
914 | ||
915 | /************************************************************* | |
916 | * Module support routines | |
917 | *************************************************************/ | |
918 | ||
919 | static int __init isdn_bsdcomp_init(void) | |
920 | { | |
921 | int answer = isdn_ppp_register_compressor (&ippp_bsd_compress); | |
922 | if (answer == 0) | |
923 | printk (KERN_INFO "PPP BSD Compression module registered\n"); | |
924 | return answer; | |
925 | } | |
926 | ||
927 | static void __exit isdn_bsdcomp_exit(void) | |
928 | { | |
929 | isdn_ppp_unregister_compressor (&ippp_bsd_compress); | |
930 | } | |
931 | ||
932 | module_init(isdn_bsdcomp_init); | |
933 | module_exit(isdn_bsdcomp_exit); |