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[PATCH] vfree and kfree cleanup in drivers/
[deliverable/linux.git] / drivers / isdn / i4l / isdn_bsdcomp.c
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 */
286 vfree(db->dict);
287 db->dict = NULL;
288
289 /*
290 * Release the string buffer
291 */
292 vfree(db->lens);
293 db->lens = NULL;
294
295 /*
296 * Finally release the structure itself.
297 */
298 kfree(db);
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);
Linux kernel - Deliverables
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