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1da177e4 LT |
1 | /* |
2 | * Update: The Berkeley copyright was changed, and the change | |
3 | * is retroactive to all "true" BSD software (ie everything | |
4 | * from UCB as opposed to other peoples code that just carried | |
5 | * the same license). The new copyright doesn't clash with the | |
6 | * GPL, so the module-only restriction has been removed.. | |
7 | */ | |
8 | ||
9 | /* Because this code is derived from the 4.3BSD compress source: | |
10 | * | |
11 | * Copyright (c) 1985, 1986 The Regents of the University of California. | |
12 | * All rights reserved. | |
13 | * | |
14 | * This code is derived from software contributed to Berkeley by | |
15 | * James A. Woods, derived from original work by Spencer Thomas | |
16 | * and Joseph Orost. | |
17 | * | |
18 | * Redistribution and use in source and binary forms, with or without | |
19 | * modification, are permitted provided that the following conditions | |
20 | * are met: | |
21 | * 1. Redistributions of source code must retain the above copyright | |
22 | * notice, this list of conditions and the following disclaimer. | |
23 | * 2. Redistributions in binary form must reproduce the above copyright | |
24 | * notice, this list of conditions and the following disclaimer in the | |
25 | * documentation and/or other materials provided with the distribution. | |
26 | * 3. All advertising materials mentioning features or use of this software | |
27 | * must display the following acknowledgement: | |
28 | * This product includes software developed by the University of | |
29 | * California, Berkeley and its contributors. | |
30 | * 4. Neither the name of the University nor the names of its contributors | |
31 | * may be used to endorse or promote products derived from this software | |
32 | * without specific prior written permission. | |
33 | * | |
34 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
35 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
36 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
37 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
38 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
39 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
40 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
41 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
42 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
43 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
44 | * SUCH DAMAGE. | |
45 | */ | |
46 | ||
47 | /* | |
48 | * This version is for use with contiguous buffers on Linux-derived systems. | |
49 | * | |
50 | * ==FILEVERSION 20000226== | |
51 | * | |
52 | * NOTE TO MAINTAINERS: | |
53 | * If you modify this file at all, please set the number above to the | |
54 | * date of the modification as YYMMDD (year month day). | |
55 | * bsd_comp.c is shipped with a PPP distribution as well as with | |
56 | * the kernel; if everyone increases the FILEVERSION number above, | |
57 | * then scripts can do the right thing when deciding whether to | |
58 | * install a new bsd_comp.c file. Don't change the format of that | |
59 | * line otherwise, so the installation script can recognize it. | |
60 | * | |
61 | * From: bsd_comp.c,v 1.3 1994/12/08 01:59:58 paulus Exp | |
62 | */ | |
63 | ||
64 | #include <linux/module.h> | |
65 | #include <linux/init.h> | |
66 | #include <linux/slab.h> | |
67 | #include <linux/vmalloc.h> | |
68 | #include <linux/string.h> | |
69 | ||
70 | #include <linux/ppp_defs.h> | |
71 | ||
72 | #undef PACKETPTR | |
73 | #define PACKETPTR 1 | |
74 | #include <linux/ppp-comp.h> | |
75 | #undef PACKETPTR | |
76 | ||
77 | #include <asm/byteorder.h> | |
78 | ||
79 | /* | |
80 | * PPP "BSD compress" compression | |
81 | * The differences between this compression and the classic BSD LZW | |
82 | * source are obvious from the requirement that the classic code worked | |
83 | * with files while this handles arbitrarily long streams that | |
84 | * are broken into packets. They are: | |
85 | * | |
86 | * When the code size expands, a block of junk is not emitted by | |
87 | * the compressor and not expected by the decompressor. | |
88 | * | |
89 | * New codes are not necessarily assigned every time an old | |
90 | * code is output by the compressor. This is because a packet | |
91 | * end forces a code to be emitted, but does not imply that a | |
92 | * new sequence has been seen. | |
93 | * | |
94 | * The compression ratio is checked at the first end of a packet | |
95 | * after the appropriate gap. Besides simplifying and speeding | |
96 | * things up, this makes it more likely that the transmitter | |
97 | * and receiver will agree when the dictionary is cleared when | |
98 | * compression is not going well. | |
99 | */ | |
100 | ||
101 | /* | |
102 | * Macros to extract protocol version and number of bits | |
103 | * from the third byte of the BSD Compress CCP configuration option. | |
104 | */ | |
105 | ||
106 | #define BSD_VERSION(x) ((x) >> 5) | |
107 | #define BSD_NBITS(x) ((x) & 0x1F) | |
108 | ||
109 | #define BSD_CURRENT_VERSION 1 | |
110 | ||
111 | /* | |
112 | * A dictionary for doing BSD compress. | |
113 | */ | |
114 | ||
115 | struct bsd_dict { | |
116 | union { /* hash value */ | |
117 | unsigned long fcode; | |
118 | struct { | |
119 | #if defined(__LITTLE_ENDIAN) /* Little endian order */ | |
120 | unsigned short prefix; /* preceding code */ | |
121 | unsigned char suffix; /* last character of new code */ | |
122 | unsigned char pad; | |
123 | #elif defined(__BIG_ENDIAN) /* Big endian order */ | |
124 | unsigned char pad; | |
125 | unsigned char suffix; /* last character of new code */ | |
126 | unsigned short prefix; /* preceding code */ | |
127 | #else | |
128 | #error Endianness not defined... | |
129 | #endif | |
130 | } hs; | |
131 | } f; | |
132 | unsigned short codem1; /* output of hash table -1 */ | |
133 | unsigned short cptr; /* map code to hash table entry */ | |
134 | }; | |
135 | ||
136 | struct bsd_db { | |
137 | int totlen; /* length of this structure */ | |
138 | unsigned int hsize; /* size of the hash table */ | |
139 | unsigned char hshift; /* used in hash function */ | |
140 | unsigned char n_bits; /* current bits/code */ | |
141 | unsigned char maxbits; /* maximum bits/code */ | |
142 | unsigned char debug; /* non-zero if debug desired */ | |
143 | unsigned char unit; /* ppp unit number */ | |
144 | unsigned short seqno; /* sequence # of next packet */ | |
145 | unsigned int mru; /* size of receive (decompress) bufr */ | |
146 | unsigned int maxmaxcode; /* largest valid code */ | |
147 | unsigned int max_ent; /* largest code in use */ | |
148 | unsigned int in_count; /* uncompressed bytes, aged */ | |
149 | unsigned int bytes_out; /* compressed bytes, aged */ | |
150 | unsigned int ratio; /* recent compression ratio */ | |
151 | unsigned int checkpoint; /* when to next check the ratio */ | |
152 | unsigned int clear_count; /* times dictionary cleared */ | |
153 | unsigned int incomp_count; /* incompressible packets */ | |
154 | unsigned int incomp_bytes; /* incompressible bytes */ | |
155 | unsigned int uncomp_count; /* uncompressed packets */ | |
156 | unsigned int uncomp_bytes; /* uncompressed bytes */ | |
157 | unsigned int comp_count; /* compressed packets */ | |
158 | unsigned int comp_bytes; /* compressed bytes */ | |
159 | unsigned short *lens; /* array of lengths of codes */ | |
160 | struct bsd_dict *dict; /* dictionary */ | |
161 | }; | |
162 | ||
163 | #define BSD_OVHD 2 /* BSD compress overhead/packet */ | |
164 | #define MIN_BSD_BITS 9 | |
165 | #define BSD_INIT_BITS MIN_BSD_BITS | |
166 | #define MAX_BSD_BITS 15 | |
167 | ||
168 | static void bsd_free (void *state); | |
169 | static void *bsd_alloc(unsigned char *options, int opt_len, int decomp); | |
170 | static void *bsd_comp_alloc (unsigned char *options, int opt_len); | |
171 | static void *bsd_decomp_alloc (unsigned char *options, int opt_len); | |
172 | ||
173 | static int bsd_init (void *db, unsigned char *options, | |
174 | int opt_len, int unit, int debug, int decomp); | |
175 | static int bsd_comp_init (void *state, unsigned char *options, | |
176 | int opt_len, int unit, int opthdr, int debug); | |
177 | static int bsd_decomp_init (void *state, unsigned char *options, | |
178 | int opt_len, int unit, int opthdr, int mru, | |
179 | int debug); | |
180 | ||
181 | static void bsd_reset (void *state); | |
182 | static void bsd_comp_stats (void *state, struct compstat *stats); | |
183 | ||
184 | static int bsd_compress (void *state, unsigned char *rptr, | |
185 | unsigned char *obuf, int isize, int osize); | |
186 | static void bsd_incomp (void *state, unsigned char *ibuf, int icnt); | |
187 | ||
188 | static int bsd_decompress (void *state, unsigned char *ibuf, int isize, | |
189 | unsigned char *obuf, int osize); | |
190 | ||
191 | /* These are in ppp_generic.c */ | |
192 | extern int ppp_register_compressor (struct compressor *cp); | |
193 | extern void ppp_unregister_compressor (struct compressor *cp); | |
194 | ||
195 | /* | |
196 | * the next two codes should not be changed lightly, as they must not | |
197 | * lie within the contiguous general code space. | |
198 | */ | |
199 | #define CLEAR 256 /* table clear output code */ | |
200 | #define FIRST 257 /* first free entry */ | |
201 | #define LAST 255 | |
202 | ||
203 | #define MAXCODE(b) ((1 << (b)) - 1) | |
204 | #define BADCODEM1 MAXCODE(MAX_BSD_BITS); | |
205 | ||
206 | #define BSD_HASH(prefix,suffix,hshift) ((((unsigned long)(suffix))<<(hshift)) \ | |
207 | ^ (unsigned long)(prefix)) | |
208 | #define BSD_KEY(prefix,suffix) ((((unsigned long)(suffix)) << 16) \ | |
209 | + (unsigned long)(prefix)) | |
210 | ||
211 | #define CHECK_GAP 10000 /* Ratio check interval */ | |
212 | ||
213 | #define RATIO_SCALE_LOG 8 | |
214 | #define RATIO_SCALE (1<<RATIO_SCALE_LOG) | |
215 | #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) | |
216 | ||
217 | /* | |
218 | * clear the dictionary | |
219 | */ | |
220 | ||
221 | static void | |
222 | bsd_clear(struct bsd_db *db) | |
223 | { | |
224 | db->clear_count++; | |
225 | db->max_ent = FIRST-1; | |
226 | db->n_bits = BSD_INIT_BITS; | |
227 | db->bytes_out = 0; | |
228 | db->in_count = 0; | |
229 | db->ratio = 0; | |
230 | db->checkpoint = CHECK_GAP; | |
231 | } | |
232 | ||
233 | /* | |
234 | * If the dictionary is full, then see if it is time to reset it. | |
235 | * | |
236 | * Compute the compression ratio using fixed-point arithmetic | |
237 | * with 8 fractional bits. | |
238 | * | |
239 | * Since we have an infinite stream instead of a single file, | |
240 | * watch only the local compression ratio. | |
241 | * | |
242 | * Since both peers must reset the dictionary at the same time even in | |
243 | * the absence of CLEAR codes (while packets are incompressible), they | |
244 | * must compute the same ratio. | |
245 | */ | |
246 | ||
247 | static int bsd_check (struct bsd_db *db) /* 1=output CLEAR */ | |
248 | { | |
249 | unsigned int new_ratio; | |
250 | ||
251 | if (db->in_count >= db->checkpoint) | |
252 | { | |
253 | /* age the ratio by limiting the size of the counts */ | |
254 | if (db->in_count >= RATIO_MAX || db->bytes_out >= RATIO_MAX) | |
255 | { | |
256 | db->in_count -= (db->in_count >> 2); | |
257 | db->bytes_out -= (db->bytes_out >> 2); | |
258 | } | |
259 | ||
260 | db->checkpoint = db->in_count + CHECK_GAP; | |
261 | ||
262 | if (db->max_ent >= db->maxmaxcode) | |
263 | { | |
264 | /* Reset the dictionary only if the ratio is worse, | |
265 | * or if it looks as if it has been poisoned | |
266 | * by incompressible data. | |
267 | * | |
268 | * This does not overflow, because | |
269 | * db->in_count <= RATIO_MAX. | |
270 | */ | |
271 | ||
272 | new_ratio = db->in_count << RATIO_SCALE_LOG; | |
273 | if (db->bytes_out != 0) | |
274 | { | |
275 | new_ratio /= db->bytes_out; | |
276 | } | |
277 | ||
278 | if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) | |
279 | { | |
280 | bsd_clear (db); | |
281 | return 1; | |
282 | } | |
283 | db->ratio = new_ratio; | |
284 | } | |
285 | } | |
286 | return 0; | |
287 | } | |
288 | ||
289 | /* | |
290 | * Return statistics. | |
291 | */ | |
292 | ||
293 | static void bsd_comp_stats (void *state, struct compstat *stats) | |
294 | { | |
295 | struct bsd_db *db = (struct bsd_db *) state; | |
296 | ||
297 | stats->unc_bytes = db->uncomp_bytes; | |
298 | stats->unc_packets = db->uncomp_count; | |
299 | stats->comp_bytes = db->comp_bytes; | |
300 | stats->comp_packets = db->comp_count; | |
301 | stats->inc_bytes = db->incomp_bytes; | |
302 | stats->inc_packets = db->incomp_count; | |
303 | stats->in_count = db->in_count; | |
304 | stats->bytes_out = db->bytes_out; | |
305 | } | |
306 | ||
307 | /* | |
308 | * Reset state, as on a CCP ResetReq. | |
309 | */ | |
310 | ||
311 | static void bsd_reset (void *state) | |
312 | { | |
313 | struct bsd_db *db = (struct bsd_db *) state; | |
314 | ||
315 | bsd_clear(db); | |
316 | ||
317 | db->seqno = 0; | |
318 | db->clear_count = 0; | |
319 | } | |
320 | ||
321 | /* | |
322 | * Release the compression structure | |
323 | */ | |
324 | ||
325 | static void bsd_free (void *state) | |
326 | { | |
327 | struct bsd_db *db = (struct bsd_db *) state; | |
328 | ||
329 | if (db) | |
330 | { | |
331 | /* | |
332 | * Release the dictionary | |
333 | */ | |
334 | if (db->dict) | |
335 | { | |
336 | vfree (db->dict); | |
337 | db->dict = NULL; | |
338 | } | |
339 | /* | |
340 | * Release the string buffer | |
341 | */ | |
342 | if (db->lens) | |
343 | { | |
344 | vfree (db->lens); | |
345 | db->lens = NULL; | |
346 | } | |
347 | /* | |
348 | * Finally release the structure itself. | |
349 | */ | |
350 | kfree (db); | |
351 | } | |
352 | } | |
353 | ||
354 | /* | |
355 | * Allocate space for a (de) compressor. | |
356 | */ | |
357 | ||
358 | static void *bsd_alloc (unsigned char *options, int opt_len, int decomp) | |
359 | { | |
360 | int bits; | |
361 | unsigned int hsize, hshift, maxmaxcode; | |
362 | struct bsd_db *db; | |
363 | ||
364 | if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3 | |
365 | || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) | |
366 | { | |
367 | return NULL; | |
368 | } | |
369 | ||
370 | bits = BSD_NBITS(options[2]); | |
371 | ||
372 | switch (bits) | |
373 | { | |
374 | case 9: /* needs 82152 for both directions */ | |
375 | case 10: /* needs 84144 */ | |
376 | case 11: /* needs 88240 */ | |
377 | case 12: /* needs 96432 */ | |
378 | hsize = 5003; | |
379 | hshift = 4; | |
380 | break; | |
381 | case 13: /* needs 176784 */ | |
382 | hsize = 9001; | |
383 | hshift = 5; | |
384 | break; | |
385 | case 14: /* needs 353744 */ | |
386 | hsize = 18013; | |
387 | hshift = 6; | |
388 | break; | |
389 | case 15: /* needs 691440 */ | |
390 | hsize = 35023; | |
391 | hshift = 7; | |
392 | break; | |
393 | case 16: /* needs 1366160--far too much, */ | |
394 | /* hsize = 69001; */ /* and 69001 is too big for cptr */ | |
395 | /* hshift = 8; */ /* in struct bsd_db */ | |
396 | /* break; */ | |
397 | default: | |
398 | return NULL; | |
399 | } | |
400 | /* | |
401 | * Allocate the main control structure for this instance. | |
402 | */ | |
403 | maxmaxcode = MAXCODE(bits); | |
404 | db = (struct bsd_db *) kmalloc (sizeof (struct bsd_db), | |
405 | GFP_KERNEL); | |
406 | if (!db) | |
407 | { | |
408 | return NULL; | |
409 | } | |
410 | ||
411 | memset (db, 0, sizeof(struct bsd_db)); | |
412 | /* | |
413 | * Allocate space for the dictionary. This may be more than one page in | |
414 | * length. | |
415 | */ | |
416 | db->dict = (struct bsd_dict *) vmalloc (hsize * | |
417 | sizeof (struct bsd_dict)); | |
418 | if (!db->dict) | |
419 | { | |
420 | bsd_free (db); | |
421 | return NULL; | |
422 | } | |
423 | ||
424 | /* | |
425 | * If this is the compression buffer then there is no length data. | |
426 | */ | |
427 | if (!decomp) | |
428 | { | |
429 | db->lens = NULL; | |
430 | } | |
431 | /* | |
432 | * For decompression, the length information is needed as well. | |
433 | */ | |
434 | else | |
435 | { | |
436 | db->lens = (unsigned short *) vmalloc ((maxmaxcode + 1) * | |
437 | sizeof (db->lens[0])); | |
438 | if (!db->lens) | |
439 | { | |
440 | bsd_free (db); | |
441 | return (NULL); | |
442 | } | |
443 | } | |
444 | /* | |
445 | * Initialize the data information for the compression code | |
446 | */ | |
447 | db->totlen = sizeof (struct bsd_db) + | |
448 | (sizeof (struct bsd_dict) * hsize); | |
449 | ||
450 | db->hsize = hsize; | |
451 | db->hshift = hshift; | |
452 | db->maxmaxcode = maxmaxcode; | |
453 | db->maxbits = bits; | |
454 | ||
455 | return (void *) db; | |
456 | } | |
457 | ||
458 | static void *bsd_comp_alloc (unsigned char *options, int opt_len) | |
459 | { | |
460 | return bsd_alloc (options, opt_len, 0); | |
461 | } | |
462 | ||
463 | static void *bsd_decomp_alloc (unsigned char *options, int opt_len) | |
464 | { | |
465 | return bsd_alloc (options, opt_len, 1); | |
466 | } | |
467 | ||
468 | /* | |
469 | * Initialize the database. | |
470 | */ | |
471 | ||
472 | static int bsd_init (void *state, unsigned char *options, | |
473 | int opt_len, int unit, int debug, int decomp) | |
474 | { | |
475 | struct bsd_db *db = state; | |
476 | int indx; | |
477 | ||
478 | if ((opt_len != 3) || (options[0] != CI_BSD_COMPRESS) || (options[1] != 3) | |
479 | || (BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) | |
480 | || (BSD_NBITS(options[2]) != db->maxbits) | |
481 | || (decomp && db->lens == NULL)) | |
482 | { | |
483 | return 0; | |
484 | } | |
485 | ||
486 | if (decomp) | |
487 | { | |
488 | indx = LAST; | |
489 | do | |
490 | { | |
491 | db->lens[indx] = 1; | |
492 | } | |
493 | while (indx-- > 0); | |
494 | } | |
495 | ||
496 | indx = db->hsize; | |
497 | while (indx-- != 0) | |
498 | { | |
499 | db->dict[indx].codem1 = BADCODEM1; | |
500 | db->dict[indx].cptr = 0; | |
501 | } | |
502 | ||
503 | db->unit = unit; | |
504 | db->mru = 0; | |
505 | #ifndef DEBUG | |
506 | if (debug) | |
507 | #endif | |
508 | db->debug = 1; | |
509 | ||
510 | bsd_reset(db); | |
511 | ||
512 | return 1; | |
513 | } | |
514 | ||
515 | static int bsd_comp_init (void *state, unsigned char *options, | |
516 | int opt_len, int unit, int opthdr, int debug) | |
517 | { | |
518 | return bsd_init (state, options, opt_len, unit, debug, 0); | |
519 | } | |
520 | ||
521 | static int bsd_decomp_init (void *state, unsigned char *options, | |
522 | int opt_len, int unit, int opthdr, int mru, | |
523 | int debug) | |
524 | { | |
525 | return bsd_init (state, options, opt_len, unit, debug, 1); | |
526 | } | |
527 | ||
528 | /* | |
529 | * Obtain pointers to the various structures in the compression tables | |
530 | */ | |
531 | ||
532 | #define dict_ptrx(p,idx) &(p->dict[idx]) | |
533 | #define lens_ptrx(p,idx) &(p->lens[idx]) | |
534 | ||
535 | #ifdef DEBUG | |
536 | static unsigned short *lens_ptr(struct bsd_db *db, int idx) | |
537 | { | |
538 | if ((unsigned int) idx > (unsigned int) db->maxmaxcode) | |
539 | { | |
540 | printk ("<9>ppp: lens_ptr(%d) > max\n", idx); | |
541 | idx = 0; | |
542 | } | |
543 | return lens_ptrx (db, idx); | |
544 | } | |
545 | ||
546 | static struct bsd_dict *dict_ptr(struct bsd_db *db, int idx) | |
547 | { | |
548 | if ((unsigned int) idx >= (unsigned int) db->hsize) | |
549 | { | |
550 | printk ("<9>ppp: dict_ptr(%d) > max\n", idx); | |
551 | idx = 0; | |
552 | } | |
553 | return dict_ptrx (db, idx); | |
554 | } | |
555 | ||
556 | #else | |
557 | #define lens_ptr(db,idx) lens_ptrx(db,idx) | |
558 | #define dict_ptr(db,idx) dict_ptrx(db,idx) | |
559 | #endif | |
560 | ||
561 | /* | |
562 | * compress a packet | |
563 | * | |
564 | * The result of this function is the size of the compressed | |
565 | * packet. A zero is returned if the packet was not compressed | |
566 | * for some reason, such as the size being larger than uncompressed. | |
567 | * | |
568 | * One change from the BSD compress command is that when the | |
569 | * code size expands, we do not output a bunch of padding. | |
570 | */ | |
571 | ||
572 | static int bsd_compress (void *state, unsigned char *rptr, unsigned char *obuf, | |
573 | int isize, int osize) | |
574 | { | |
575 | struct bsd_db *db; | |
576 | int hshift; | |
577 | unsigned int max_ent; | |
578 | unsigned int n_bits; | |
579 | unsigned int bitno; | |
580 | unsigned long accm; | |
581 | int ent; | |
582 | unsigned long fcode; | |
583 | struct bsd_dict *dictp; | |
584 | unsigned char c; | |
585 | int hval; | |
586 | int disp; | |
587 | int ilen; | |
588 | int mxcode; | |
589 | unsigned char *wptr; | |
590 | int olen; | |
591 | ||
592 | #define PUTBYTE(v) \ | |
593 | { \ | |
594 | ++olen; \ | |
595 | if (wptr) \ | |
596 | { \ | |
597 | *wptr++ = (unsigned char) (v); \ | |
598 | if (olen >= osize) \ | |
599 | { \ | |
600 | wptr = NULL; \ | |
601 | } \ | |
602 | } \ | |
603 | } | |
604 | ||
605 | #define OUTPUT(ent) \ | |
606 | { \ | |
607 | bitno -= n_bits; \ | |
608 | accm |= ((ent) << bitno); \ | |
609 | do \ | |
610 | { \ | |
611 | PUTBYTE(accm >> 24); \ | |
612 | accm <<= 8; \ | |
613 | bitno += 8; \ | |
614 | } \ | |
615 | while (bitno <= 24); \ | |
616 | } | |
617 | ||
618 | /* | |
619 | * If the protocol is not in the range we're interested in, | |
620 | * just return without compressing the packet. If it is, | |
621 | * the protocol becomes the first byte to compress. | |
622 | */ | |
623 | ||
624 | ent = PPP_PROTOCOL(rptr); | |
625 | if (ent < 0x21 || ent > 0xf9) | |
626 | { | |
627 | return 0; | |
628 | } | |
629 | ||
630 | db = (struct bsd_db *) state; | |
631 | hshift = db->hshift; | |
632 | max_ent = db->max_ent; | |
633 | n_bits = db->n_bits; | |
634 | bitno = 32; | |
635 | accm = 0; | |
636 | mxcode = MAXCODE (n_bits); | |
637 | ||
638 | /* Initialize the output pointers */ | |
639 | wptr = obuf; | |
640 | olen = PPP_HDRLEN + BSD_OVHD; | |
641 | ||
642 | if (osize > isize) | |
643 | { | |
644 | osize = isize; | |
645 | } | |
646 | ||
647 | /* This is the PPP header information */ | |
648 | if (wptr) | |
649 | { | |
650 | *wptr++ = PPP_ADDRESS(rptr); | |
651 | *wptr++ = PPP_CONTROL(rptr); | |
652 | *wptr++ = 0; | |
653 | *wptr++ = PPP_COMP; | |
654 | *wptr++ = db->seqno >> 8; | |
655 | *wptr++ = db->seqno; | |
656 | } | |
657 | ||
658 | /* Skip the input header */ | |
659 | rptr += PPP_HDRLEN; | |
660 | isize -= PPP_HDRLEN; | |
661 | ilen = ++isize; /* Low byte of protocol is counted as input */ | |
662 | ||
663 | while (--ilen > 0) | |
664 | { | |
665 | c = *rptr++; | |
666 | fcode = BSD_KEY (ent, c); | |
667 | hval = BSD_HASH (ent, c, hshift); | |
668 | dictp = dict_ptr (db, hval); | |
669 | ||
670 | /* Validate and then check the entry. */ | |
671 | if (dictp->codem1 >= max_ent) | |
672 | { | |
673 | goto nomatch; | |
674 | } | |
675 | ||
676 | if (dictp->f.fcode == fcode) | |
677 | { | |
678 | ent = dictp->codem1 + 1; | |
679 | continue; /* found (prefix,suffix) */ | |
680 | } | |
681 | ||
682 | /* continue probing until a match or invalid entry */ | |
683 | disp = (hval == 0) ? 1 : hval; | |
684 | ||
685 | do | |
686 | { | |
687 | hval += disp; | |
688 | if (hval >= db->hsize) | |
689 | { | |
690 | hval -= db->hsize; | |
691 | } | |
692 | dictp = dict_ptr (db, hval); | |
693 | if (dictp->codem1 >= max_ent) | |
694 | { | |
695 | goto nomatch; | |
696 | } | |
697 | } | |
698 | while (dictp->f.fcode != fcode); | |
699 | ||
700 | ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */ | |
701 | continue; | |
702 | ||
703 | nomatch: | |
704 | OUTPUT(ent); /* output the prefix */ | |
705 | ||
706 | /* code -> hashtable */ | |
707 | if (max_ent < db->maxmaxcode) | |
708 | { | |
709 | struct bsd_dict *dictp2; | |
710 | struct bsd_dict *dictp3; | |
711 | int indx; | |
712 | ||
713 | /* expand code size if needed */ | |
714 | if (max_ent >= mxcode) | |
715 | { | |
716 | db->n_bits = ++n_bits; | |
717 | mxcode = MAXCODE (n_bits); | |
718 | } | |
719 | ||
720 | /* Invalidate old hash table entry using | |
721 | * this code, and then take it over. | |
722 | */ | |
723 | ||
724 | dictp2 = dict_ptr (db, max_ent + 1); | |
725 | indx = dictp2->cptr; | |
726 | dictp3 = dict_ptr (db, indx); | |
727 | ||
728 | if (dictp3->codem1 == max_ent) | |
729 | { | |
730 | dictp3->codem1 = BADCODEM1; | |
731 | } | |
732 | ||
733 | dictp2->cptr = hval; | |
734 | dictp->codem1 = max_ent; | |
735 | dictp->f.fcode = fcode; | |
736 | db->max_ent = ++max_ent; | |
737 | ||
738 | if (db->lens) | |
739 | { | |
740 | unsigned short *len1 = lens_ptr (db, max_ent); | |
741 | unsigned short *len2 = lens_ptr (db, ent); | |
742 | *len1 = *len2 + 1; | |
743 | } | |
744 | } | |
745 | ent = c; | |
746 | } | |
747 | ||
748 | OUTPUT(ent); /* output the last code */ | |
749 | ||
750 | db->bytes_out += olen - PPP_HDRLEN - BSD_OVHD; | |
751 | db->uncomp_bytes += isize; | |
752 | db->in_count += isize; | |
753 | ++db->uncomp_count; | |
754 | ++db->seqno; | |
755 | ||
756 | if (bitno < 32) | |
757 | { | |
758 | ++db->bytes_out; /* must be set before calling bsd_check */ | |
759 | } | |
760 | ||
761 | /* | |
762 | * Generate the clear command if needed | |
763 | */ | |
764 | ||
765 | if (bsd_check(db)) | |
766 | { | |
767 | OUTPUT (CLEAR); | |
768 | } | |
769 | ||
770 | /* | |
771 | * Pad dribble bits of last code with ones. | |
772 | * Do not emit a completely useless byte of ones. | |
773 | */ | |
774 | ||
775 | if (bitno != 32) | |
776 | { | |
777 | PUTBYTE((accm | (0xff << (bitno-8))) >> 24); | |
778 | } | |
779 | ||
780 | /* | |
781 | * Increase code size if we would have without the packet | |
782 | * boundary because the decompressor will do so. | |
783 | */ | |
784 | ||
785 | if (max_ent >= mxcode && max_ent < db->maxmaxcode) | |
786 | { | |
787 | db->n_bits++; | |
788 | } | |
789 | ||
790 | /* If output length is too large then this is an incomplete frame. */ | |
791 | if (wptr == NULL) | |
792 | { | |
793 | ++db->incomp_count; | |
794 | db->incomp_bytes += isize; | |
795 | olen = 0; | |
796 | } | |
797 | else /* Count the number of compressed frames */ | |
798 | { | |
799 | ++db->comp_count; | |
800 | db->comp_bytes += olen; | |
801 | } | |
802 | ||
803 | /* Return the resulting output length */ | |
804 | return olen; | |
805 | #undef OUTPUT | |
806 | #undef PUTBYTE | |
807 | } | |
808 | ||
809 | /* | |
810 | * Update the "BSD Compress" dictionary on the receiver for | |
811 | * incompressible data by pretending to compress the incoming data. | |
812 | */ | |
813 | ||
814 | static void bsd_incomp (void *state, unsigned char *ibuf, int icnt) | |
815 | { | |
816 | (void) bsd_compress (state, ibuf, (char *) 0, icnt, 0); | |
817 | } | |
818 | ||
819 | /* | |
820 | * Decompress "BSD Compress". | |
821 | * | |
822 | * Because of patent problems, we return DECOMP_ERROR for errors | |
823 | * found by inspecting the input data and for system problems, but | |
824 | * DECOMP_FATALERROR for any errors which could possibly be said to | |
825 | * be being detected "after" decompression. For DECOMP_ERROR, | |
826 | * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be | |
827 | * infringing a patent of Motorola's if we do, so we take CCP down | |
828 | * instead. | |
829 | * | |
830 | * Given that the frame has the correct sequence number and a good FCS, | |
831 | * errors such as invalid codes in the input most likely indicate a | |
832 | * bug, so we return DECOMP_FATALERROR for them in order to turn off | |
833 | * compression, even though they are detected by inspecting the input. | |
834 | */ | |
835 | ||
836 | static int bsd_decompress (void *state, unsigned char *ibuf, int isize, | |
837 | unsigned char *obuf, int osize) | |
838 | { | |
839 | struct bsd_db *db; | |
840 | unsigned int max_ent; | |
841 | unsigned long accm; | |
842 | unsigned int bitno; /* 1st valid bit in accm */ | |
843 | unsigned int n_bits; | |
844 | unsigned int tgtbitno; /* bitno when we have a code */ | |
845 | struct bsd_dict *dictp; | |
846 | int explen; | |
847 | int seq; | |
848 | unsigned int incode; | |
849 | unsigned int oldcode; | |
850 | unsigned int finchar; | |
851 | unsigned char *p; | |
852 | unsigned char *wptr; | |
853 | int adrs; | |
854 | int ctrl; | |
855 | int ilen; | |
856 | int codelen; | |
857 | int extra; | |
858 | ||
859 | db = (struct bsd_db *) state; | |
860 | max_ent = db->max_ent; | |
861 | accm = 0; | |
862 | bitno = 32; /* 1st valid bit in accm */ | |
863 | n_bits = db->n_bits; | |
864 | tgtbitno = 32 - n_bits; /* bitno when we have a code */ | |
865 | ||
866 | /* | |
867 | * Save the address/control from the PPP header | |
868 | * and then get the sequence number. | |
869 | */ | |
870 | ||
871 | adrs = PPP_ADDRESS (ibuf); | |
872 | ctrl = PPP_CONTROL (ibuf); | |
873 | ||
874 | seq = (ibuf[4] << 8) + ibuf[5]; | |
875 | ||
876 | ibuf += (PPP_HDRLEN + 2); | |
877 | ilen = isize - (PPP_HDRLEN + 2); | |
878 | ||
879 | /* | |
880 | * Check the sequence number and give up if it differs from | |
881 | * the value we're expecting. | |
882 | */ | |
883 | ||
884 | if (seq != db->seqno) | |
885 | { | |
886 | if (db->debug) | |
887 | { | |
888 | printk("bsd_decomp%d: bad sequence # %d, expected %d\n", | |
889 | db->unit, seq, db->seqno - 1); | |
890 | } | |
891 | return DECOMP_ERROR; | |
892 | } | |
893 | ||
894 | ++db->seqno; | |
895 | db->bytes_out += ilen; | |
896 | ||
897 | /* | |
898 | * Fill in the ppp header, but not the last byte of the protocol | |
899 | * (that comes from the decompressed data). | |
900 | */ | |
901 | ||
902 | wptr = obuf; | |
903 | *wptr++ = adrs; | |
904 | *wptr++ = ctrl; | |
905 | *wptr++ = 0; | |
906 | ||
907 | oldcode = CLEAR; | |
908 | explen = 3; | |
909 | ||
910 | /* | |
911 | * Keep the checkpoint correctly so that incompressible packets | |
912 | * clear the dictionary at the proper times. | |
913 | */ | |
914 | ||
915 | for (;;) | |
916 | { | |
917 | if (ilen-- <= 0) | |
918 | { | |
919 | db->in_count += (explen - 3); /* don't count the header */ | |
920 | break; | |
921 | } | |
922 | ||
923 | /* | |
924 | * Accumulate bytes until we have a complete code. | |
925 | * Then get the next code, relying on the 32-bit, | |
926 | * unsigned accm to mask the result. | |
927 | */ | |
928 | ||
929 | bitno -= 8; | |
930 | accm |= *ibuf++ << bitno; | |
931 | if (tgtbitno < bitno) | |
932 | { | |
933 | continue; | |
934 | } | |
935 | ||
936 | incode = accm >> tgtbitno; | |
937 | accm <<= n_bits; | |
938 | bitno += n_bits; | |
939 | ||
940 | /* | |
941 | * The dictionary must only be cleared at the end of a packet. | |
942 | */ | |
943 | ||
944 | if (incode == CLEAR) | |
945 | { | |
946 | if (ilen > 0) | |
947 | { | |
948 | if (db->debug) | |
949 | { | |
950 | printk("bsd_decomp%d: bad CLEAR\n", db->unit); | |
951 | } | |
952 | return DECOMP_FATALERROR; /* probably a bug */ | |
953 | } | |
954 | ||
955 | bsd_clear(db); | |
956 | break; | |
957 | } | |
958 | ||
959 | if ((incode > max_ent + 2) || (incode > db->maxmaxcode) | |
960 | || (incode > max_ent && oldcode == CLEAR)) | |
961 | { | |
962 | if (db->debug) | |
963 | { | |
964 | printk("bsd_decomp%d: bad code 0x%x oldcode=0x%x ", | |
965 | db->unit, incode, oldcode); | |
966 | printk("max_ent=0x%x explen=%d seqno=%d\n", | |
967 | max_ent, explen, db->seqno); | |
968 | } | |
969 | return DECOMP_FATALERROR; /* probably a bug */ | |
970 | } | |
971 | ||
972 | /* Special case for KwKwK string. */ | |
973 | if (incode > max_ent) | |
974 | { | |
975 | finchar = oldcode; | |
976 | extra = 1; | |
977 | } | |
978 | else | |
979 | { | |
980 | finchar = incode; | |
981 | extra = 0; | |
982 | } | |
983 | ||
984 | codelen = *(lens_ptr (db, finchar)); | |
985 | explen += codelen + extra; | |
986 | if (explen > osize) | |
987 | { | |
988 | if (db->debug) | |
989 | { | |
990 | printk("bsd_decomp%d: ran out of mru\n", db->unit); | |
991 | #ifdef DEBUG | |
992 | printk(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n", | |
993 | ilen, finchar, codelen, explen); | |
994 | #endif | |
995 | } | |
996 | return DECOMP_FATALERROR; | |
997 | } | |
998 | ||
999 | /* | |
1000 | * Decode this code and install it in the decompressed buffer. | |
1001 | */ | |
1002 | ||
1003 | wptr += codelen; | |
1004 | p = wptr; | |
1005 | while (finchar > LAST) | |
1006 | { | |
1007 | struct bsd_dict *dictp2 = dict_ptr (db, finchar); | |
1008 | ||
1009 | dictp = dict_ptr (db, dictp2->cptr); | |
1010 | #ifdef DEBUG | |
1011 | if (--codelen <= 0 || dictp->codem1 != finchar-1) | |
1012 | { | |
1013 | if (codelen <= 0) | |
1014 | { | |
1015 | printk("bsd_decomp%d: fell off end of chain ", db->unit); | |
1016 | printk("0x%x at 0x%x by 0x%x, max_ent=0x%x\n", | |
1017 | incode, finchar, dictp2->cptr, max_ent); | |
1018 | } | |
1019 | else | |
1020 | { | |
1021 | if (dictp->codem1 != finchar-1) | |
1022 | { | |
1023 | printk("bsd_decomp%d: bad code chain 0x%x " | |
1024 | "finchar=0x%x ", | |
1025 | db->unit, incode, finchar); | |
1026 | ||
1027 | printk("oldcode=0x%x cptr=0x%x codem1=0x%x\n", | |
1028 | oldcode, dictp2->cptr, dictp->codem1); | |
1029 | } | |
1030 | } | |
1031 | return DECOMP_FATALERROR; | |
1032 | } | |
1033 | #endif | |
1034 | *--p = dictp->f.hs.suffix; | |
1035 | finchar = dictp->f.hs.prefix; | |
1036 | } | |
1037 | *--p = finchar; | |
1038 | ||
1039 | #ifdef DEBUG | |
1040 | if (--codelen != 0) | |
1041 | { | |
1042 | printk("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", | |
1043 | db->unit, codelen, incode, max_ent); | |
1044 | } | |
1045 | #endif | |
1046 | ||
1047 | if (extra) /* the KwKwK case again */ | |
1048 | { | |
1049 | *wptr++ = finchar; | |
1050 | } | |
1051 | ||
1052 | /* | |
1053 | * If not first code in a packet, and | |
1054 | * if not out of code space, then allocate a new code. | |
1055 | * | |
1056 | * Keep the hash table correct so it can be used | |
1057 | * with uncompressed packets. | |
1058 | */ | |
1059 | ||
1060 | if (oldcode != CLEAR && max_ent < db->maxmaxcode) | |
1061 | { | |
1062 | struct bsd_dict *dictp2, *dictp3; | |
1063 | unsigned short *lens1, *lens2; | |
1064 | unsigned long fcode; | |
1065 | int hval, disp, indx; | |
1066 | ||
1067 | fcode = BSD_KEY(oldcode,finchar); | |
1068 | hval = BSD_HASH(oldcode,finchar,db->hshift); | |
1069 | dictp = dict_ptr (db, hval); | |
1070 | ||
1071 | /* look for a free hash table entry */ | |
1072 | if (dictp->codem1 < max_ent) | |
1073 | { | |
1074 | disp = (hval == 0) ? 1 : hval; | |
1075 | do | |
1076 | { | |
1077 | hval += disp; | |
1078 | if (hval >= db->hsize) | |
1079 | { | |
1080 | hval -= db->hsize; | |
1081 | } | |
1082 | dictp = dict_ptr (db, hval); | |
1083 | } | |
1084 | while (dictp->codem1 < max_ent); | |
1085 | } | |
1086 | ||
1087 | /* | |
1088 | * Invalidate previous hash table entry | |
1089 | * assigned this code, and then take it over | |
1090 | */ | |
1091 | ||
1092 | dictp2 = dict_ptr (db, max_ent + 1); | |
1093 | indx = dictp2->cptr; | |
1094 | dictp3 = dict_ptr (db, indx); | |
1095 | ||
1096 | if (dictp3->codem1 == max_ent) | |
1097 | { | |
1098 | dictp3->codem1 = BADCODEM1; | |
1099 | } | |
1100 | ||
1101 | dictp2->cptr = hval; | |
1102 | dictp->codem1 = max_ent; | |
1103 | dictp->f.fcode = fcode; | |
1104 | db->max_ent = ++max_ent; | |
1105 | ||
1106 | /* Update the length of this string. */ | |
1107 | lens1 = lens_ptr (db, max_ent); | |
1108 | lens2 = lens_ptr (db, oldcode); | |
1109 | *lens1 = *lens2 + 1; | |
1110 | ||
1111 | /* Expand code size if needed. */ | |
1112 | if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) | |
1113 | { | |
1114 | db->n_bits = ++n_bits; | |
1115 | tgtbitno = 32-n_bits; | |
1116 | } | |
1117 | } | |
1118 | oldcode = incode; | |
1119 | } | |
1120 | ||
1121 | ++db->comp_count; | |
1122 | ++db->uncomp_count; | |
1123 | db->comp_bytes += isize - BSD_OVHD - PPP_HDRLEN; | |
1124 | db->uncomp_bytes += explen; | |
1125 | ||
1126 | if (bsd_check(db)) | |
1127 | { | |
1128 | if (db->debug) | |
1129 | { | |
1130 | printk("bsd_decomp%d: peer should have cleared dictionary on %d\n", | |
1131 | db->unit, db->seqno - 1); | |
1132 | } | |
1133 | } | |
1134 | return explen; | |
1135 | } | |
1136 | ||
1137 | /************************************************************* | |
1138 | * Table of addresses for the BSD compression module | |
1139 | *************************************************************/ | |
1140 | ||
1141 | static struct compressor ppp_bsd_compress = { | |
1142 | .compress_proto = CI_BSD_COMPRESS, | |
1143 | .comp_alloc = bsd_comp_alloc, | |
1144 | .comp_free = bsd_free, | |
1145 | .comp_init = bsd_comp_init, | |
1146 | .comp_reset = bsd_reset, | |
1147 | .compress = bsd_compress, | |
1148 | .comp_stat = bsd_comp_stats, | |
1149 | .decomp_alloc = bsd_decomp_alloc, | |
1150 | .decomp_free = bsd_free, | |
1151 | .decomp_init = bsd_decomp_init, | |
1152 | .decomp_reset = bsd_reset, | |
1153 | .decompress = bsd_decompress, | |
1154 | .incomp = bsd_incomp, | |
1155 | .decomp_stat = bsd_comp_stats, | |
1156 | .owner = THIS_MODULE | |
1157 | }; | |
1158 | ||
1159 | /************************************************************* | |
1160 | * Module support routines | |
1161 | *************************************************************/ | |
1162 | ||
1163 | static int __init bsdcomp_init(void) | |
1164 | { | |
1165 | int answer = ppp_register_compressor(&ppp_bsd_compress); | |
1166 | if (answer == 0) | |
1167 | printk(KERN_INFO "PPP BSD Compression module registered\n"); | |
1168 | return answer; | |
1169 | } | |
1170 | ||
1171 | static void __exit bsdcomp_cleanup(void) | |
1172 | { | |
1173 | ppp_unregister_compressor(&ppp_bsd_compress); | |
1174 | } | |
1175 | ||
1176 | module_init(bsdcomp_init); | |
1177 | module_exit(bsdcomp_cleanup); | |
1178 | MODULE_LICENSE("Dual BSD/GPL"); | |
1179 | MODULE_ALIAS("ppp-compress-" __stringify(CI_BSD_COMPRESS)); |