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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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/*
Joe Perches475be4d2012-02-19 19:52:38 -080010 * Update: The Berkeley copyright was changed, and the change
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 * 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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070059#include <linux/types.h>
60#include <linux/fcntl.h>
61#include <linux/interrupt.h>
62#include <linux/ptrace.h>
63#include <linux/ioport.h>
64#include <linux/in.h>
65#include <linux/slab.h>
66#include <linux/tty.h>
67#include <linux/errno.h>
68#include <linux/string.h> /* used in new tty drivers */
69#include <linux/signal.h> /* used in new tty drivers */
70#include <linux/bitops.h>
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072#include <asm/byteorder.h>
73#include <asm/types.h>
74
75#include <linux/if.h>
76
77#include <linux/if_ether.h>
78#include <linux/netdevice.h>
79#include <linux/skbuff.h>
80#include <linux/inet.h>
81#include <linux/ioctl.h>
82#include <linux/vmalloc.h>
83
84#include <linux/ppp_defs.h>
85
86#include <linux/isdn.h>
87#include <linux/isdn_ppp.h>
88#include <linux/ip.h>
89#include <linux/tcp.h>
90#include <linux/if_arp.h>
91#include <linux/ppp-comp.h>
92
93#include "isdn_ppp.h"
94
95MODULE_DESCRIPTION("ISDN4Linux: BSD Compression for PPP over ISDN");
96MODULE_LICENSE("Dual BSD/GPL");
97
98#define BSD_VERSION(x) ((x) >> 5)
99#define BSD_NBITS(x) ((x) & 0x1F)
100
101#define BSD_CURRENT_VERSION 1
102
103#define DEBUG 1
104
105/*
106 * A dictionary for doing BSD compress.
107 */
108
109struct bsd_dict {
110 u32 fcode;
111 u16 codem1; /* output of hash table -1 */
112 u16 cptr; /* map code to hash table entry */
113};
114
115struct bsd_db {
116 int totlen; /* length of this structure */
117 unsigned int hsize; /* size of the hash table */
118 unsigned char hshift; /* used in hash function */
119 unsigned char n_bits; /* current bits/code */
120 unsigned char maxbits; /* maximum bits/code */
121 unsigned char debug; /* non-zero if debug desired */
122 unsigned char unit; /* ppp unit number */
Joe Perches475be4d2012-02-19 19:52:38 -0800123 u16 seqno; /* sequence # of next packet */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 unsigned int mru; /* size of receive (decompress) bufr */
125 unsigned int maxmaxcode; /* largest valid code */
126 unsigned int max_ent; /* largest code in use */
127 unsigned int in_count; /* uncompressed bytes, aged */
128 unsigned int bytes_out; /* compressed bytes, aged */
129 unsigned int ratio; /* recent compression ratio */
130 unsigned int checkpoint; /* when to next check the ratio */
131 unsigned int clear_count; /* times dictionary cleared */
132 unsigned int incomp_count; /* incompressible packets */
133 unsigned int incomp_bytes; /* incompressible bytes */
134 unsigned int uncomp_count; /* uncompressed packets */
135 unsigned int uncomp_bytes; /* uncompressed bytes */
136 unsigned int comp_count; /* compressed packets */
137 unsigned int comp_bytes; /* compressed bytes */
138 unsigned short *lens; /* array of lengths of codes */
139 struct bsd_dict *dict; /* dictionary */
140 int xmit;
141};
142
143#define BSD_OVHD 2 /* BSD compress overhead/packet */
144#define MIN_BSD_BITS 9
145#define BSD_INIT_BITS MIN_BSD_BITS
146#define MAX_BSD_BITS 15
147
148/*
149 * the next two codes should not be changed lightly, as they must not
150 * lie within the contiguous general code space.
151 */
152#define CLEAR 256 /* table clear output code */
153#define FIRST 257 /* first free entry */
154#define LAST 255
155
156#define MAXCODE(b) ((1 << (b)) - 1)
Phil Carmody497888c2011-07-14 15:07:13 +0300157#define BADCODEM1 MAXCODE(MAX_BSD_BITS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158
Joe Perches475be4d2012-02-19 19:52:38 -0800159#define BSD_HASH(prefix, suffix, hshift) ((((unsigned long)(suffix)) << (hshift)) \
160 ^ (unsigned long)(prefix))
161#define BSD_KEY(prefix, suffix) ((((unsigned long)(suffix)) << 16) \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 + (unsigned long)(prefix))
163
164#define CHECK_GAP 10000 /* Ratio check interval */
165
166#define RATIO_SCALE_LOG 8
Joe Perches475be4d2012-02-19 19:52:38 -0800167#define RATIO_SCALE (1 << RATIO_SCALE_LOG)
168#define RATIO_MAX (0x7fffffff >> RATIO_SCALE_LOG)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169
170/*
171 * clear the dictionary
172 */
173
174static void bsd_clear(struct bsd_db *db)
175{
176 db->clear_count++;
Joe Perches475be4d2012-02-19 19:52:38 -0800177 db->max_ent = FIRST - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 db->n_bits = BSD_INIT_BITS;
179 db->bytes_out = 0;
180 db->in_count = 0;
181 db->incomp_count = 0;
182 db->ratio = 0;
183 db->checkpoint = CHECK_GAP;
184}
185
186/*
187 * If the dictionary is full, then see if it is time to reset it.
188 *
189 * Compute the compression ratio using fixed-point arithmetic
190 * with 8 fractional bits.
191 *
192 * Since we have an infinite stream instead of a single file,
193 * watch only the local compression ratio.
194 *
195 * Since both peers must reset the dictionary at the same time even in
196 * the absence of CLEAR codes (while packets are incompressible), they
197 * must compute the same ratio.
198 */
Joe Perches475be4d2012-02-19 19:52:38 -0800199static int bsd_check(struct bsd_db *db) /* 1=output CLEAR */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200{
Joe Perches475be4d2012-02-19 19:52:38 -0800201 unsigned int new_ratio;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202
Joe Perches475be4d2012-02-19 19:52:38 -0800203 if (db->in_count >= db->checkpoint)
204 {
205 /* age the ratio by limiting the size of the counts */
206 if (db->in_count >= RATIO_MAX || db->bytes_out >= RATIO_MAX)
207 {
208 db->in_count -= (db->in_count >> 2);
209 db->bytes_out -= (db->bytes_out >> 2);
210 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211
Joe Perches475be4d2012-02-19 19:52:38 -0800212 db->checkpoint = db->in_count + CHECK_GAP;
213
214 if (db->max_ent >= db->maxmaxcode)
215 {
216 /* Reset the dictionary only if the ratio is worse,
217 * or if it looks as if it has been poisoned
218 * by incompressible data.
219 *
220 * This does not overflow, because
221 * db->in_count <= RATIO_MAX.
222 */
223
224 new_ratio = db->in_count << RATIO_SCALE_LOG;
225 if (db->bytes_out != 0)
226 {
227 new_ratio /= db->bytes_out;
228 }
229
230 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE)
231 {
232 bsd_clear(db);
233 return 1;
234 }
235 db->ratio = new_ratio;
236 }
237 }
238 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239}
240
241/*
242 * Return statistics.
243 */
244
Joe Perches475be4d2012-02-19 19:52:38 -0800245static void bsd_stats(void *state, struct compstat *stats)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246{
247 struct bsd_db *db = (struct bsd_db *) state;
Joe Perches475be4d2012-02-19 19:52:38 -0800248
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 stats->unc_bytes = db->uncomp_bytes;
250 stats->unc_packets = db->uncomp_count;
251 stats->comp_bytes = db->comp_bytes;
252 stats->comp_packets = db->comp_count;
253 stats->inc_bytes = db->incomp_bytes;
254 stats->inc_packets = db->incomp_count;
255 stats->in_count = db->in_count;
256 stats->bytes_out = db->bytes_out;
257}
258
259/*
260 * Reset state, as on a CCP ResetReq.
261 */
Joe Perches475be4d2012-02-19 19:52:38 -0800262static void bsd_reset(void *state, unsigned char code, unsigned char id,
263 unsigned char *data, unsigned len,
264 struct isdn_ppp_resetparams *rsparm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265{
266 struct bsd_db *db = (struct bsd_db *) state;
267
268 bsd_clear(db);
269 db->seqno = 0;
270 db->clear_count = 0;
271}
272
273/*
274 * Release the compression structure
275 */
Joe Perches475be4d2012-02-19 19:52:38 -0800276static void bsd_free(void *state)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277{
278 struct bsd_db *db = (struct bsd_db *) state;
279
280 if (db) {
281 /*
282 * Release the dictionary
283 */
Jesper Juhlf91012102005-09-10 00:26:54 -0700284 vfree(db->dict);
285 db->dict = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286
287 /*
288 * Release the string buffer
289 */
Jesper Juhlf91012102005-09-10 00:26:54 -0700290 vfree(db->lens);
291 db->lens = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292
293 /*
294 * Finally release the structure itself.
295 */
Jesper Juhlf91012102005-09-10 00:26:54 -0700296 kfree(db);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 }
298}
299
300
301/*
302 * Allocate space for a (de) compressor.
303 */
Joe Perches475be4d2012-02-19 19:52:38 -0800304static void *bsd_alloc(struct isdn_ppp_comp_data *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305{
306 int bits;
307 unsigned int hsize, hshift, maxmaxcode;
308 struct bsd_db *db;
309 int decomp;
310
311 static unsigned int htab[][2] = {
Joe Perches475be4d2012-02-19 19:52:38 -0800312 { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } ,
313 { 9001 , 5 } , { 18013 , 6 } , { 35023 , 7 } , { 69001 , 8 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 };
Joe Perches475be4d2012-02-19 19:52:38 -0800315
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 if (data->optlen != 1 || data->num != CI_BSD_COMPRESS
Joe Perches475be4d2012-02-19 19:52:38 -0800317 || BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 return NULL;
319
320 bits = BSD_NBITS(data->options[0]);
321
Joe Perches475be4d2012-02-19 19:52:38 -0800322 if (bits < 9 || bits > 15)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 return NULL;
324
Joe Perches475be4d2012-02-19 19:52:38 -0800325 hsize = htab[bits - 9][0];
326 hshift = htab[bits - 9][1];
327
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 /*
329 * Allocate the main control structure for this instance.
330 */
331 maxmaxcode = MAXCODE(bits);
Joe Perches475be4d2012-02-19 19:52:38 -0800332 db = kzalloc(sizeof(struct bsd_db), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 if (!db)
334 return NULL;
335
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 db->xmit = data->flags & IPPP_COMP_FLAG_XMIT;
337 decomp = db->xmit ? 0 : 1;
338
339 /*
340 * Allocate space for the dictionary. This may be more than one page in
341 * length.
342 */
Jesper Juhl7c8347a2007-08-24 23:25:33 -0700343 db->dict = vmalloc(hsize * sizeof(struct bsd_dict));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 if (!db->dict) {
Joe Perches475be4d2012-02-19 19:52:38 -0800345 bsd_free(db);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 return NULL;
347 }
348
349 /*
350 * If this is the compression buffer then there is no length data.
351 * For decompression, the length information is needed as well.
352 */
353 if (!decomp)
354 db->lens = NULL;
355 else {
Jesper Juhl7c8347a2007-08-24 23:25:33 -0700356 db->lens = vmalloc((maxmaxcode + 1) * sizeof(db->lens[0]));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 if (!db->lens) {
Joe Perches475be4d2012-02-19 19:52:38 -0800358 bsd_free(db);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 return (NULL);
360 }
361 }
362
363 /*
364 * Initialize the data information for the compression code
365 */
Joe Perches475be4d2012-02-19 19:52:38 -0800366 db->totlen = sizeof(struct bsd_db) + (sizeof(struct bsd_dict) * hsize);
367 db->hsize = hsize;
368 db->hshift = hshift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 db->maxmaxcode = maxmaxcode;
Joe Perches475be4d2012-02-19 19:52:38 -0800370 db->maxbits = bits;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371
Joe Perches475be4d2012-02-19 19:52:38 -0800372 return (void *)db;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373}
374
375/*
376 * Initialize the database.
377 */
Joe Perches475be4d2012-02-19 19:52:38 -0800378static int bsd_init(void *state, struct isdn_ppp_comp_data *data, int unit, int debug)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379{
380 struct bsd_db *db = state;
381 int indx;
382 int decomp;
383
Joe Perches475be4d2012-02-19 19:52:38 -0800384 if (!state || !data) {
385 printk(KERN_ERR "isdn_bsd_init: [%d] ERR, state %lx data %lx\n", unit, (long)state, (long)data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 return 0;
387 }
388
389 decomp = db->xmit ? 0 : 1;
Joe Perches475be4d2012-02-19 19:52:38 -0800390
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 if (data->optlen != 1 || data->num != CI_BSD_COMPRESS
Joe Perches475be4d2012-02-19 19:52:38 -0800392 || (BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION)
393 || (BSD_NBITS(data->options[0]) != db->maxbits)
394 || (decomp && db->lens == NULL)) {
395 printk(KERN_ERR "isdn_bsd: %d %d %d %d %lx\n", data->optlen, data->num, data->options[0], decomp, (unsigned long)db->lens);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 return 0;
397 }
398
399 if (decomp)
Joe Perches475be4d2012-02-19 19:52:38 -0800400 for (indx = LAST; indx >= 0; indx--)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 db->lens[indx] = 1;
402
403 indx = db->hsize;
404 while (indx-- != 0) {
405 db->dict[indx].codem1 = BADCODEM1;
406 db->dict[indx].cptr = 0;
407 }
408
409 db->unit = unit;
410 db->mru = 0;
411
412 db->debug = 1;
Joe Perches475be4d2012-02-19 19:52:38 -0800413
414 bsd_reset(db, 0, 0, NULL, 0, NULL);
415
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 return 1;
417}
418
419/*
420 * Obtain pointers to the various structures in the compression tables
421 */
422
Joe Perches475be4d2012-02-19 19:52:38 -0800423#define dict_ptrx(p, idx) &(p->dict[idx])
424#define lens_ptrx(p, idx) &(p->lens[idx])
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425
426#ifdef DEBUG
427static unsigned short *lens_ptr(struct bsd_db *db, int idx)
428{
429 if ((unsigned int) idx > (unsigned int) db->maxmaxcode) {
Joe Perches475be4d2012-02-19 19:52:38 -0800430 printk(KERN_DEBUG "<9>ppp: lens_ptr(%d) > max\n", idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 idx = 0;
432 }
Joe Perches475be4d2012-02-19 19:52:38 -0800433 return lens_ptrx(db, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434}
435
436static struct bsd_dict *dict_ptr(struct bsd_db *db, int idx)
437{
438 if ((unsigned int) idx >= (unsigned int) db->hsize) {
Joe Perches475be4d2012-02-19 19:52:38 -0800439 printk(KERN_DEBUG "<9>ppp: dict_ptr(%d) > max\n", idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 idx = 0;
441 }
Joe Perches475be4d2012-02-19 19:52:38 -0800442 return dict_ptrx(db, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443}
444
445#else
Joe Perches475be4d2012-02-19 19:52:38 -0800446#define lens_ptr(db, idx) lens_ptrx(db, idx)
447#define dict_ptr(db, idx) dict_ptrx(db, idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448#endif
449
450/*
451 * compress a packet
452 */
Joe Perches475be4d2012-02-19 19:52:38 -0800453static int bsd_compress(void *state, struct sk_buff *skb_in, struct sk_buff *skb_out, int proto)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454{
455 struct bsd_db *db;
456 int hshift;
457 unsigned int max_ent;
458 unsigned int n_bits;
459 unsigned int bitno;
460 unsigned long accm;
461 int ent;
462 unsigned long fcode;
463 struct bsd_dict *dictp;
464 unsigned char c;
Joe Perches475be4d2012-02-19 19:52:38 -0800465 int hval, disp, ilen, mxcode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 unsigned char *rptr = skb_in->data;
467 int isize = skb_in->len;
468
Joe Perches475be4d2012-02-19 19:52:38 -0800469#define OUTPUT(ent) \
470 { \
471 bitno -= n_bits; \
472 accm |= ((ent) << bitno); \
473 do { \
474 if (skb_out && skb_tailroom(skb_out) > 0) \
475 *(skb_put(skb_out, 1)) = (unsigned char)(accm >> 24); \
476 accm <<= 8; \
477 bitno += 8; \
478 } while (bitno <= 24); \
479 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480
481 /*
482 * If the protocol is not in the range we're interested in,
483 * just return without compressing the packet. If it is,
484 * the protocol becomes the first byte to compress.
485 */
Joe Perches475be4d2012-02-19 19:52:38 -0800486 printk(KERN_DEBUG "bsd_compress called with %x\n", proto);
487
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 ent = proto;
Joe Perches475be4d2012-02-19 19:52:38 -0800489 if (proto < 0x21 || proto > 0xf9 || !(proto & 0x1))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 return 0;
491
492 db = (struct bsd_db *) state;
493 hshift = db->hshift;
494 max_ent = db->max_ent;
495 n_bits = db->n_bits;
496 bitno = 32;
497 accm = 0;
Joe Perches475be4d2012-02-19 19:52:38 -0800498 mxcode = MAXCODE(n_bits);
499
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 /* This is the PPP header information */
Joe Perches475be4d2012-02-19 19:52:38 -0800501 if (skb_out && skb_tailroom(skb_out) >= 2) {
502 char *v = skb_put(skb_out, 2);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 /* we only push our own data on the header,
Joe Perches475be4d2012-02-19 19:52:38 -0800504 AC,PC and protos is pushed by caller */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505 v[0] = db->seqno >> 8;
506 v[1] = db->seqno;
507 }
508
Joe Perches475be4d2012-02-19 19:52:38 -0800509 ilen = ++isize; /* This is off by one, but that is what is in draft! */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510
511 while (--ilen > 0) {
Joe Perches475be4d2012-02-19 19:52:38 -0800512 c = *rptr++;
513 fcode = BSD_KEY(ent, c);
514 hval = BSD_HASH(ent, c, hshift);
515 dictp = dict_ptr(db, hval);
516
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 /* Validate and then check the entry. */
518 if (dictp->codem1 >= max_ent)
519 goto nomatch;
520
521 if (dictp->fcode == fcode) {
522 ent = dictp->codem1 + 1;
523 continue; /* found (prefix,suffix) */
524 }
Joe Perches475be4d2012-02-19 19:52:38 -0800525
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 /* continue probing until a match or invalid entry */
527 disp = (hval == 0) ? 1 : hval;
528
529 do {
530 hval += disp;
531 if (hval >= db->hsize)
532 hval -= db->hsize;
Joe Perches475be4d2012-02-19 19:52:38 -0800533 dictp = dict_ptr(db, hval);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 if (dictp->codem1 >= max_ent)
535 goto nomatch;
536 } while (dictp->fcode != fcode);
537
538 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
539 continue;
Joe Perches475be4d2012-02-19 19:52:38 -0800540
541 nomatch:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 OUTPUT(ent); /* output the prefix */
Joe Perches475be4d2012-02-19 19:52:38 -0800543
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 /* code -> hashtable */
545 if (max_ent < db->maxmaxcode) {
546 struct bsd_dict *dictp2;
547 struct bsd_dict *dictp3;
548 int indx;
549
550 /* expand code size if needed */
551 if (max_ent >= mxcode) {
552 db->n_bits = ++n_bits;
Joe Perches475be4d2012-02-19 19:52:38 -0800553 mxcode = MAXCODE(n_bits);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 }
Joe Perches475be4d2012-02-19 19:52:38 -0800555
556 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557 * Invalidate old hash table entry using
558 * this code, and then take it over.
559 */
Joe Perches475be4d2012-02-19 19:52:38 -0800560 dictp2 = dict_ptr(db, max_ent + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 indx = dictp2->cptr;
Joe Perches475be4d2012-02-19 19:52:38 -0800562 dictp3 = dict_ptr(db, indx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563
564 if (dictp3->codem1 == max_ent)
565 dictp3->codem1 = BADCODEM1;
566
567 dictp2->cptr = hval;
568 dictp->codem1 = max_ent;
569 dictp->fcode = fcode;
570 db->max_ent = ++max_ent;
571
572 if (db->lens) {
Joe Perches475be4d2012-02-19 19:52:38 -0800573 unsigned short *len1 = lens_ptr(db, max_ent);
574 unsigned short *len2 = lens_ptr(db, ent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 *len1 = *len2 + 1;
576 }
577 }
578 ent = c;
579 }
Joe Perches475be4d2012-02-19 19:52:38 -0800580
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 OUTPUT(ent); /* output the last code */
582
Joe Perches475be4d2012-02-19 19:52:38 -0800583 if (skb_out)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 db->bytes_out += skb_out->len; /* Do not count bytes from here */
585 db->uncomp_bytes += isize;
586 db->in_count += isize;
587 ++db->uncomp_count;
588 ++db->seqno;
589
590 if (bitno < 32)
591 ++db->bytes_out; /* must be set before calling bsd_check */
592
593 /*
594 * Generate the clear command if needed
595 */
596
597 if (bsd_check(db))
Joe Perches475be4d2012-02-19 19:52:38 -0800598 OUTPUT(CLEAR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599
600 /*
601 * Pad dribble bits of last code with ones.
602 * Do not emit a completely useless byte of ones.
603 */
Joe Perches475be4d2012-02-19 19:52:38 -0800604 if (bitno < 32 && skb_out && skb_tailroom(skb_out) > 0)
605 *(skb_put(skb_out, 1)) = (unsigned char)((accm | (0xff << (bitno - 8))) >> 24);
606
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 /*
608 * Increase code size if we would have without the packet
609 * boundary because the decompressor will do so.
610 */
611 if (max_ent >= mxcode && max_ent < db->maxmaxcode)
612 db->n_bits++;
613
614 /* If output length is too large then this is an incompressible frame. */
Joe Perches475be4d2012-02-19 19:52:38 -0800615 if (!skb_out || (skb_out && skb_out->len >= skb_in->len)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 ++db->incomp_count;
617 db->incomp_bytes += isize;
618 return 0;
619 }
620
621 /* Count the number of compressed frames */
622 ++db->comp_count;
623 db->comp_bytes += skb_out->len;
624 return skb_out->len;
625
626#undef OUTPUT
627}
628
629/*
630 * Update the "BSD Compress" dictionary on the receiver for
631 * incompressible data by pretending to compress the incoming data.
632 */
Joe Perches475be4d2012-02-19 19:52:38 -0800633static void bsd_incomp(void *state, struct sk_buff *skb_in, int proto)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634{
Joe Perches475be4d2012-02-19 19:52:38 -0800635 bsd_compress(state, skb_in, NULL, proto);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636}
637
638/*
639 * Decompress "BSD Compress".
640 */
Joe Perches475be4d2012-02-19 19:52:38 -0800641static int bsd_decompress(void *state, struct sk_buff *skb_in, struct sk_buff *skb_out,
642 struct isdn_ppp_resetparams *rsparm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643{
644 struct bsd_db *db;
645 unsigned int max_ent;
646 unsigned long accm;
647 unsigned int bitno; /* 1st valid bit in accm */
648 unsigned int n_bits;
649 unsigned int tgtbitno; /* bitno when we have a code */
650 struct bsd_dict *dictp;
651 int seq;
652 unsigned int incode;
653 unsigned int oldcode;
654 unsigned int finchar;
Joe Perches475be4d2012-02-19 19:52:38 -0800655 unsigned char *p, *ibuf;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 int ilen;
657 int codelen;
658 int extra;
659
660 db = (struct bsd_db *) state;
661 max_ent = db->max_ent;
662 accm = 0;
663 bitno = 32; /* 1st valid bit in accm */
664 n_bits = db->n_bits;
665 tgtbitno = 32 - n_bits; /* bitno when we have a code */
666
667 printk(KERN_DEBUG "bsd_decompress called\n");
668
Joe Perches475be4d2012-02-19 19:52:38 -0800669 if (!skb_in || !skb_out) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 printk(KERN_ERR "bsd_decompress called with NULL parameter\n");
671 return DECOMP_ERROR;
672 }
Joe Perches475be4d2012-02-19 19:52:38 -0800673
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 /*
675 * Get the sequence number.
676 */
Joe Perches475be4d2012-02-19 19:52:38 -0800677 if ((p = skb_pull(skb_in, 2)) == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 return DECOMP_ERROR;
679 }
Joe Perches475be4d2012-02-19 19:52:38 -0800680 p -= 2;
681 seq = (p[0] << 8) + p[1];
682 ilen = skb_in->len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 ibuf = skb_in->data;
684
685 /*
686 * Check the sequence number and give up if it differs from
687 * the value we're expecting.
688 */
689 if (seq != db->seqno) {
690 if (db->debug) {
691 printk(KERN_DEBUG "bsd_decomp%d: bad sequence # %d, expected %d\n",
Joe Perches475be4d2012-02-19 19:52:38 -0800692 db->unit, seq, db->seqno - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 }
694 return DECOMP_ERROR;
695 }
696
697 ++db->seqno;
698 db->bytes_out += ilen;
699
Joe Perches475be4d2012-02-19 19:52:38 -0800700 if (skb_tailroom(skb_out) > 0)
701 *(skb_put(skb_out, 1)) = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 else
703 return DECOMP_ERR_NOMEM;
Joe Perches475be4d2012-02-19 19:52:38 -0800704
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 oldcode = CLEAR;
706
707 /*
708 * Keep the checkpoint correctly so that incompressible packets
709 * clear the dictionary at the proper times.
710 */
711
712 for (;;) {
713 if (ilen-- <= 0) {
714 db->in_count += (skb_out->len - 1); /* don't count the header */
715 break;
716 }
717
718 /*
719 * Accumulate bytes until we have a complete code.
720 * Then get the next code, relying on the 32-bit,
721 * unsigned accm to mask the result.
722 */
723
724 bitno -= 8;
725 accm |= *ibuf++ << bitno;
726 if (tgtbitno < bitno)
727 continue;
728
729 incode = accm >> tgtbitno;
730 accm <<= n_bits;
731 bitno += n_bits;
732
733 /*
734 * The dictionary must only be cleared at the end of a packet.
735 */
Joe Perches475be4d2012-02-19 19:52:38 -0800736
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 if (incode == CLEAR) {
738 if (ilen > 0) {
739 if (db->debug)
740 printk(KERN_DEBUG "bsd_decomp%d: bad CLEAR\n", db->unit);
741 return DECOMP_FATALERROR; /* probably a bug */
742 }
743 bsd_clear(db);
744 break;
745 }
746
747 if ((incode > max_ent + 2) || (incode > db->maxmaxcode)
Joe Perches475be4d2012-02-19 19:52:38 -0800748 || (incode > max_ent && oldcode == CLEAR)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749 if (db->debug) {
750 printk(KERN_DEBUG "bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
Joe Perches475be4d2012-02-19 19:52:38 -0800751 db->unit, incode, oldcode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 printk(KERN_DEBUG "max_ent=0x%x skb->Len=%d seqno=%d\n",
Joe Perches475be4d2012-02-19 19:52:38 -0800753 max_ent, skb_out->len, db->seqno);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 }
755 return DECOMP_FATALERROR; /* probably a bug */
756 }
Joe Perches475be4d2012-02-19 19:52:38 -0800757
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 /* Special case for KwKwK string. */
759 if (incode > max_ent) {
760 finchar = oldcode;
761 extra = 1;
762 } else {
763 finchar = incode;
764 extra = 0;
765 }
766
Joe Perches475be4d2012-02-19 19:52:38 -0800767 codelen = *(lens_ptr(db, finchar));
768 if (skb_tailroom(skb_out) < codelen + extra) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 if (db->debug) {
770 printk(KERN_DEBUG "bsd_decomp%d: ran out of mru\n", db->unit);
771#ifdef DEBUG
772 printk(KERN_DEBUG " len=%d, finchar=0x%x, codelen=%d,skblen=%d\n",
Joe Perches475be4d2012-02-19 19:52:38 -0800773 ilen, finchar, codelen, skb_out->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774#endif
775 }
776 return DECOMP_FATALERROR;
777 }
778
779 /*
780 * Decode this code and install it in the decompressed buffer.
781 */
782
Joe Perches475be4d2012-02-19 19:52:38 -0800783 p = skb_put(skb_out, codelen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 p += codelen;
785 while (finchar > LAST) {
Joe Perches475be4d2012-02-19 19:52:38 -0800786 struct bsd_dict *dictp2 = dict_ptr(db, finchar);
787
788 dictp = dict_ptr(db, dictp2->cptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789
790#ifdef DEBUG
Joe Perches475be4d2012-02-19 19:52:38 -0800791 if (--codelen <= 0 || dictp->codem1 != finchar - 1) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 if (codelen <= 0) {
793 printk(KERN_ERR "bsd_decomp%d: fell off end of chain ", db->unit);
794 printk(KERN_ERR "0x%x at 0x%x by 0x%x, max_ent=0x%x\n", incode, finchar, dictp2->cptr, max_ent);
795 } else {
Joe Perches475be4d2012-02-19 19:52:38 -0800796 if (dictp->codem1 != finchar - 1) {
797 printk(KERN_ERR "bsd_decomp%d: bad code chain 0x%x finchar=0x%x ", db->unit, incode, finchar);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 printk(KERN_ERR "oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, dictp2->cptr, dictp->codem1);
799 }
800 }
801 return DECOMP_FATALERROR;
802 }
803#endif
804
805 {
806 u32 fcode = dictp->fcode;
807 *--p = (fcode >> 16) & 0xff;
808 finchar = fcode & 0xffff;
809 }
810 }
811 *--p = finchar;
Joe Perches475be4d2012-02-19 19:52:38 -0800812
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813#ifdef DEBUG
814 if (--codelen != 0)
815 printk(KERN_ERR "bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", db->unit, codelen, incode, max_ent);
816#endif
Joe Perches475be4d2012-02-19 19:52:38 -0800817
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 if (extra) /* the KwKwK case again */
Joe Perches475be4d2012-02-19 19:52:38 -0800819 *(skb_put(skb_out, 1)) = finchar;
820
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 /*
822 * If not first code in a packet, and
823 * if not out of code space, then allocate a new code.
824 *
825 * Keep the hash table correct so it can be used
826 * with uncompressed packets.
827 */
828 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
829 struct bsd_dict *dictp2, *dictp3;
Joe Perches475be4d2012-02-19 19:52:38 -0800830 u16 *lens1, *lens2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 unsigned long fcode;
832 int hval, disp, indx;
Joe Perches475be4d2012-02-19 19:52:38 -0800833
834 fcode = BSD_KEY(oldcode, finchar);
835 hval = BSD_HASH(oldcode, finchar, db->hshift);
836 dictp = dict_ptr(db, hval);
837
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 /* look for a free hash table entry */
839 if (dictp->codem1 < max_ent) {
840 disp = (hval == 0) ? 1 : hval;
841 do {
842 hval += disp;
843 if (hval >= db->hsize)
844 hval -= db->hsize;
Joe Perches475be4d2012-02-19 19:52:38 -0800845 dictp = dict_ptr(db, hval);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 } while (dictp->codem1 < max_ent);
847 }
Joe Perches475be4d2012-02-19 19:52:38 -0800848
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849 /*
850 * Invalidate previous hash table entry
851 * assigned this code, and then take it over
852 */
853
Joe Perches475be4d2012-02-19 19:52:38 -0800854 dictp2 = dict_ptr(db, max_ent + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 indx = dictp2->cptr;
Joe Perches475be4d2012-02-19 19:52:38 -0800856 dictp3 = dict_ptr(db, indx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857
858 if (dictp3->codem1 == max_ent)
859 dictp3->codem1 = BADCODEM1;
860
861 dictp2->cptr = hval;
862 dictp->codem1 = max_ent;
863 dictp->fcode = fcode;
864 db->max_ent = ++max_ent;
865
866 /* Update the length of this string. */
Joe Perches475be4d2012-02-19 19:52:38 -0800867 lens1 = lens_ptr(db, max_ent);
868 lens2 = lens_ptr(db, oldcode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 *lens1 = *lens2 + 1;
Joe Perches475be4d2012-02-19 19:52:38 -0800870
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871 /* Expand code size if needed. */
872 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
873 db->n_bits = ++n_bits;
874 tgtbitno = 32-n_bits;
875 }
876 }
877 oldcode = incode;
878 }
879
880 ++db->comp_count;
881 ++db->uncomp_count;
882 db->comp_bytes += skb_in->len - BSD_OVHD;
883 db->uncomp_bytes += skb_out->len;
884
885 if (bsd_check(db)) {
886 if (db->debug)
887 printk(KERN_DEBUG "bsd_decomp%d: peer should have cleared dictionary on %d\n",
Joe Perches475be4d2012-02-19 19:52:38 -0800888 db->unit, db->seqno - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 }
890 return skb_out->len;
891}
892
893/*************************************************************
894 * Table of addresses for the BSD compression module
895 *************************************************************/
896
897static struct isdn_ppp_compressor ippp_bsd_compress = {
898 .owner = THIS_MODULE,
899 .num = CI_BSD_COMPRESS,
900 .alloc = bsd_alloc,
901 .free = bsd_free,
902 .init = bsd_init,
903 .reset = bsd_reset,
904 .compress = bsd_compress,
905 .decompress = bsd_decompress,
906 .incomp = bsd_incomp,
907 .stat = bsd_stats,
908};
909
910/*************************************************************
911 * Module support routines
912 *************************************************************/
913
914static int __init isdn_bsdcomp_init(void)
915{
Joe Perches475be4d2012-02-19 19:52:38 -0800916 int answer = isdn_ppp_register_compressor(&ippp_bsd_compress);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 if (answer == 0)
Joe Perches475be4d2012-02-19 19:52:38 -0800918 printk(KERN_INFO "PPP BSD Compression module registered\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919 return answer;
920}
921
922static void __exit isdn_bsdcomp_exit(void)
923{
Joe Perches475be4d2012-02-19 19:52:38 -0800924 isdn_ppp_unregister_compressor(&ippp_bsd_compress);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925}
926
927module_init(isdn_bsdcomp_init);
928module_exit(isdn_bsdcomp_exit);