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1da177e4
LT
1/*
2 * ==FILEVERSION 980319==
3 *
4 * ppp_deflate.c - interface the zlib procedures for Deflate compression
5 * and decompression (as used by gzip) to the PPP code.
6 * This version is for use with Linux kernel 1.3.X.
7 *
8 * Copyright (c) 1994 The Australian National University.
9 * All rights reserved.
10 *
11 * Permission to use, copy, modify, and distribute this software and its
12 * documentation is hereby granted, provided that the above copyright
13 * notice appears in all copies. This software is provided without any
14 * warranty, express or implied. The Australian National University
15 * makes no representations about the suitability of this software for
16 * any purpose.
17 *
18 * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
19 * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
20 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
21 * THE AUSTRALIAN NATIONAL UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY
22 * OF SUCH DAMAGE.
23 *
24 * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
25 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
26 * AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
27 * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
28 * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
29 * OR MODIFICATIONS.
30 *
31 * From: deflate.c,v 1.1 1996/01/18 03:17:48 paulus Exp
32 */
33
34#include <linux/module.h>
35#include <linux/slab.h>
36#include <linux/vmalloc.h>
37#include <linux/init.h>
38#include <linux/string.h>
39
40#include <linux/ppp_defs.h>
41#include <linux/ppp-comp.h>
42
43#include <linux/zlib.h>
44
45/*
46 * State for a Deflate (de)compressor.
47 */
48struct ppp_deflate_state {
49 int seqno;
50 int w_size;
51 int unit;
52 int mru;
53 int debug;
54 z_stream strm;
55 struct compstat stats;
56};
57
58#define DEFLATE_OVHD 2 /* Deflate overhead/packet */
59
60static void *z_comp_alloc(unsigned char *options, int opt_len);
61static void *z_decomp_alloc(unsigned char *options, int opt_len);
62static void z_comp_free(void *state);
63static void z_decomp_free(void *state);
64static int z_comp_init(void *state, unsigned char *options,
65 int opt_len,
66 int unit, int hdrlen, int debug);
67static int z_decomp_init(void *state, unsigned char *options,
68 int opt_len,
69 int unit, int hdrlen, int mru, int debug);
70static int z_compress(void *state, unsigned char *rptr,
71 unsigned char *obuf,
72 int isize, int osize);
73static void z_incomp(void *state, unsigned char *ibuf, int icnt);
74static int z_decompress(void *state, unsigned char *ibuf,
75 int isize, unsigned char *obuf, int osize);
76static void z_comp_reset(void *state);
77static void z_decomp_reset(void *state);
78static void z_comp_stats(void *state, struct compstat *stats);
79
80/**
81 * z_comp_free - free the memory used by a compressor
82 * @arg: pointer to the private state for the compressor.
83 */
84static void z_comp_free(void *arg)
85{
86 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
87
88 if (state) {
89 zlib_deflateEnd(&state->strm);
96edf83c 90 vfree(state->strm.workspace);
1da177e4
LT
91 kfree(state);
92 }
93}
94
95/**
96 * z_comp_alloc - allocate space for a compressor.
97 * @options: pointer to CCP option data
98 * @opt_len: length of the CCP option at @options.
99 *
100 * The @options pointer points to the a buffer containing the
101 * CCP option data for the compression being negotiated. It is
102 * formatted according to RFC1979, and describes the window
103 * size that the peer is requesting that we use in compressing
104 * data to be sent to it.
105 *
106 * Returns the pointer to the private state for the compressor,
107 * or NULL if we could not allocate enough memory.
108 */
109static void *z_comp_alloc(unsigned char *options, int opt_len)
110{
111 struct ppp_deflate_state *state;
112 int w_size;
113
114 if (opt_len != CILEN_DEFLATE
115 || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
116 || options[1] != CILEN_DEFLATE
117 || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
118 || options[3] != DEFLATE_CHK_SEQUENCE)
119 return NULL;
120 w_size = DEFLATE_SIZE(options[2]);
121 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
122 return NULL;
123
dd00cc48 124 state = kzalloc(sizeof(*state),
1da177e4
LT
125 GFP_KERNEL);
126 if (state == NULL)
127 return NULL;
128
1da177e4
LT
129 state->strm.next_in = NULL;
130 state->w_size = w_size;
131 state->strm.workspace = vmalloc(zlib_deflate_workspacesize());
132 if (state->strm.workspace == NULL)
133 goto out_free;
134
135 if (zlib_deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION,
136 DEFLATE_METHOD_VAL, -w_size, 8, Z_DEFAULT_STRATEGY)
137 != Z_OK)
138 goto out_free;
139 return (void *) state;
140
141out_free:
142 z_comp_free(state);
143 return NULL;
144}
145
146/**
147 * z_comp_init - initialize a previously-allocated compressor.
148 * @arg: pointer to the private state for the compressor
149 * @options: pointer to the CCP option data describing the
150 * compression that was negotiated with the peer
151 * @opt_len: length of the CCP option data at @options
152 * @unit: PPP unit number for diagnostic messages
153 * @hdrlen: ignored (present for backwards compatibility)
154 * @debug: debug flag; if non-zero, debug messages are printed.
155 *
156 * The CCP options described by @options must match the options
157 * specified when the compressor was allocated. The compressor
158 * history is reset. Returns 0 for failure (CCP options don't
159 * match) or 1 for success.
160 */
161static int z_comp_init(void *arg, unsigned char *options, int opt_len,
162 int unit, int hdrlen, int debug)
163{
164 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
165
166 if (opt_len < CILEN_DEFLATE
167 || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
168 || options[1] != CILEN_DEFLATE
169 || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
170 || DEFLATE_SIZE(options[2]) != state->w_size
171 || options[3] != DEFLATE_CHK_SEQUENCE)
172 return 0;
173
174 state->seqno = 0;
175 state->unit = unit;
176 state->debug = debug;
177
178 zlib_deflateReset(&state->strm);
179
180 return 1;
181}
182
183/**
184 * z_comp_reset - reset a previously-allocated compressor.
185 * @arg: pointer to private state for the compressor.
186 *
187 * This clears the history for the compressor and makes it
188 * ready to start emitting a new compressed stream.
189 */
190static void z_comp_reset(void *arg)
191{
192 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
193
194 state->seqno = 0;
195 zlib_deflateReset(&state->strm);
196}
197
198/**
199 * z_compress - compress a PPP packet with Deflate compression.
200 * @arg: pointer to private state for the compressor
201 * @rptr: uncompressed packet (input)
202 * @obuf: compressed packet (output)
203 * @isize: size of uncompressed packet
204 * @osize: space available at @obuf
205 *
206 * Returns the length of the compressed packet, or 0 if the
207 * packet is incompressible.
208 */
209int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,
210 int isize, int osize)
211{
212 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
213 int r, proto, off, olen, oavail;
214 unsigned char *wptr;
215
216 /*
217 * Check that the protocol is in the range we handle.
218 */
219 proto = PPP_PROTOCOL(rptr);
220 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
221 return 0;
222
223 /* Don't generate compressed packets which are larger than
224 the uncompressed packet. */
225 if (osize > isize)
226 osize = isize;
227
228 wptr = obuf;
229
230 /*
231 * Copy over the PPP header and store the 2-byte sequence number.
232 */
233 wptr[0] = PPP_ADDRESS(rptr);
234 wptr[1] = PPP_CONTROL(rptr);
235 wptr[2] = PPP_COMP >> 8;
236 wptr[3] = PPP_COMP;
237 wptr += PPP_HDRLEN;
238 wptr[0] = state->seqno >> 8;
239 wptr[1] = state->seqno;
240 wptr += DEFLATE_OVHD;
241 olen = PPP_HDRLEN + DEFLATE_OVHD;
242 state->strm.next_out = wptr;
243 state->strm.avail_out = oavail = osize - olen;
244 ++state->seqno;
245
246 off = (proto > 0xff) ? 2 : 3; /* skip 1st proto byte if 0 */
247 rptr += off;
248 state->strm.next_in = rptr;
249 state->strm.avail_in = (isize - off);
250
251 for (;;) {
252 r = zlib_deflate(&state->strm, Z_PACKET_FLUSH);
253 if (r != Z_OK) {
254 if (state->debug)
255 printk(KERN_ERR
256 "z_compress: deflate returned %d\n", r);
257 break;
258 }
259 if (state->strm.avail_out == 0) {
260 olen += oavail;
261 state->strm.next_out = NULL;
262 state->strm.avail_out = oavail = 1000000;
263 } else {
264 break; /* all done */
265 }
266 }
267 olen += oavail - state->strm.avail_out;
268
269 /*
270 * See if we managed to reduce the size of the packet.
271 */
272 if (olen < isize) {
273 state->stats.comp_bytes += olen;
274 state->stats.comp_packets++;
275 } else {
276 state->stats.inc_bytes += isize;
277 state->stats.inc_packets++;
278 olen = 0;
279 }
280 state->stats.unc_bytes += isize;
281 state->stats.unc_packets++;
282
283 return olen;
284}
285
286/**
287 * z_comp_stats - return compression statistics for a compressor
288 * or decompressor.
289 * @arg: pointer to private space for the (de)compressor
290 * @stats: pointer to a struct compstat to receive the result.
291 */
292static void z_comp_stats(void *arg, struct compstat *stats)
293{
294 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
295
296 *stats = state->stats;
297}
298
299/**
300 * z_decomp_free - Free the memory used by a decompressor.
301 * @arg: pointer to private space for the decompressor.
302 */
303static void z_decomp_free(void *arg)
304{
305 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
306
307 if (state) {
308 zlib_inflateEnd(&state->strm);
96edf83c 309 kfree(state->strm.workspace);
1da177e4
LT
310 kfree(state);
311 }
312}
313
314/**
315 * z_decomp_alloc - allocate space for a decompressor.
316 * @options: pointer to CCP option data
317 * @opt_len: length of the CCP option at @options.
318 *
319 * The @options pointer points to the a buffer containing the
320 * CCP option data for the compression being negotiated. It is
321 * formatted according to RFC1979, and describes the window
322 * size that we are requesting the peer to use in compressing
323 * data to be sent to us.
324 *
325 * Returns the pointer to the private state for the decompressor,
326 * or NULL if we could not allocate enough memory.
327 */
328static void *z_decomp_alloc(unsigned char *options, int opt_len)
329{
330 struct ppp_deflate_state *state;
331 int w_size;
332
333 if (opt_len != CILEN_DEFLATE
334 || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
335 || options[1] != CILEN_DEFLATE
336 || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
337 || options[3] != DEFLATE_CHK_SEQUENCE)
338 return NULL;
339 w_size = DEFLATE_SIZE(options[2]);
340 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
341 return NULL;
342
dd00cc48 343 state = kzalloc(sizeof(*state), GFP_KERNEL);
1da177e4
LT
344 if (state == NULL)
345 return NULL;
346
1da177e4
LT
347 state->w_size = w_size;
348 state->strm.next_out = NULL;
349 state->strm.workspace = kmalloc(zlib_inflate_workspacesize(),
350 GFP_KERNEL|__GFP_REPEAT);
351 if (state->strm.workspace == NULL)
352 goto out_free;
353
354 if (zlib_inflateInit2(&state->strm, -w_size) != Z_OK)
355 goto out_free;
356 return (void *) state;
357
358out_free:
359 z_decomp_free(state);
360 return NULL;
361}
362
363/**
364 * z_decomp_init - initialize a previously-allocated decompressor.
365 * @arg: pointer to the private state for the decompressor
366 * @options: pointer to the CCP option data describing the
367 * compression that was negotiated with the peer
368 * @opt_len: length of the CCP option data at @options
369 * @unit: PPP unit number for diagnostic messages
370 * @hdrlen: ignored (present for backwards compatibility)
371 * @mru: maximum length of decompressed packets
372 * @debug: debug flag; if non-zero, debug messages are printed.
373 *
374 * The CCP options described by @options must match the options
375 * specified when the decompressor was allocated. The decompressor
376 * history is reset. Returns 0 for failure (CCP options don't
377 * match) or 1 for success.
378 */
379static int z_decomp_init(void *arg, unsigned char *options, int opt_len,
380 int unit, int hdrlen, int mru, int debug)
381{
382 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
383
384 if (opt_len < CILEN_DEFLATE
385 || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
386 || options[1] != CILEN_DEFLATE
387 || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
388 || DEFLATE_SIZE(options[2]) != state->w_size
389 || options[3] != DEFLATE_CHK_SEQUENCE)
390 return 0;
391
392 state->seqno = 0;
393 state->unit = unit;
394 state->debug = debug;
395 state->mru = mru;
396
397 zlib_inflateReset(&state->strm);
398
399 return 1;
400}
401
402/**
403 * z_decomp_reset - reset a previously-allocated decompressor.
404 * @arg: pointer to private state for the decompressor.
405 *
406 * This clears the history for the decompressor and makes it
407 * ready to receive a new compressed stream.
408 */
409static void z_decomp_reset(void *arg)
410{
411 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
412
413 state->seqno = 0;
414 zlib_inflateReset(&state->strm);
415}
416
417/**
418 * z_decompress - decompress a Deflate-compressed packet.
419 * @arg: pointer to private state for the decompressor
420 * @ibuf: pointer to input (compressed) packet data
421 * @isize: length of input packet
422 * @obuf: pointer to space for output (decompressed) packet
423 * @osize: amount of space available at @obuf
424 *
425 * Because of patent problems, we return DECOMP_ERROR for errors
426 * found by inspecting the input data and for system problems, but
427 * DECOMP_FATALERROR for any errors which could possibly be said to
428 * be being detected "after" decompression. For DECOMP_ERROR,
429 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
430 * infringing a patent of Motorola's if we do, so we take CCP down
431 * instead.
432 *
433 * Given that the frame has the correct sequence number and a good FCS,
434 * errors such as invalid codes in the input most likely indicate a
435 * bug, so we return DECOMP_FATALERROR for them in order to turn off
436 * compression, even though they are detected by inspecting the input.
437 */
438int z_decompress(void *arg, unsigned char *ibuf, int isize,
439 unsigned char *obuf, int osize)
440{
441 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
442 int olen, seq, r;
443 int decode_proto, overflow;
444 unsigned char overflow_buf[1];
445
446 if (isize <= PPP_HDRLEN + DEFLATE_OVHD) {
447 if (state->debug)
448 printk(KERN_DEBUG "z_decompress%d: short pkt (%d)\n",
449 state->unit, isize);
450 return DECOMP_ERROR;
451 }
452
453 /* Check the sequence number. */
454 seq = (ibuf[PPP_HDRLEN] << 8) + ibuf[PPP_HDRLEN+1];
455 if (seq != (state->seqno & 0xffff)) {
456 if (state->debug)
457 printk(KERN_DEBUG "z_decompress%d: bad seq # %d, expected %d\n",
458 state->unit, seq, state->seqno & 0xffff);
459 return DECOMP_ERROR;
460 }
461 ++state->seqno;
462
463 /*
464 * Fill in the first part of the PPP header. The protocol field
465 * comes from the decompressed data.
466 */
467 obuf[0] = PPP_ADDRESS(ibuf);
468 obuf[1] = PPP_CONTROL(ibuf);
469 obuf[2] = 0;
470
471 /*
472 * Set up to call inflate. We set avail_out to 1 initially so we can
473 * look at the first byte of the output and decide whether we have
474 * a 1-byte or 2-byte protocol field.
475 */
476 state->strm.next_in = ibuf + PPP_HDRLEN + DEFLATE_OVHD;
477 state->strm.avail_in = isize - (PPP_HDRLEN + DEFLATE_OVHD);
478 state->strm.next_out = obuf + 3;
479 state->strm.avail_out = 1;
480 decode_proto = 1;
481 overflow = 0;
482
483 /*
484 * Call inflate, supplying more input or output as needed.
485 */
486 for (;;) {
487 r = zlib_inflate(&state->strm, Z_PACKET_FLUSH);
488 if (r != Z_OK) {
489 if (state->debug)
490 printk(KERN_DEBUG "z_decompress%d: inflate returned %d (%s)\n",
491 state->unit, r, (state->strm.msg? state->strm.msg: ""));
492 return DECOMP_FATALERROR;
493 }
494 if (state->strm.avail_out != 0)
495 break; /* all done */
496 if (decode_proto) {
497 state->strm.avail_out = osize - PPP_HDRLEN;
498 if ((obuf[3] & 1) == 0) {
499 /* 2-byte protocol field */
500 obuf[2] = obuf[3];
501 --state->strm.next_out;
502 ++state->strm.avail_out;
503 }
504 decode_proto = 0;
505 } else if (!overflow) {
506 /*
507 * We've filled up the output buffer; the only way to
508 * find out whether inflate has any more characters
509 * left is to give it another byte of output space.
510 */
511 state->strm.next_out = overflow_buf;
512 state->strm.avail_out = 1;
513 overflow = 1;
514 } else {
515 if (state->debug)
516 printk(KERN_DEBUG "z_decompress%d: ran out of mru\n",
517 state->unit);
518 return DECOMP_FATALERROR;
519 }
520 }
521
522 if (decode_proto) {
523 if (state->debug)
524 printk(KERN_DEBUG "z_decompress%d: didn't get proto\n",
525 state->unit);
526 return DECOMP_ERROR;
527 }
528
529 olen = osize + overflow - state->strm.avail_out;
530 state->stats.unc_bytes += olen;
531 state->stats.unc_packets++;
532 state->stats.comp_bytes += isize;
533 state->stats.comp_packets++;
534
535 return olen;
536}
537
538/**
539 * z_incomp - add incompressible input data to the history.
540 * @arg: pointer to private state for the decompressor
541 * @ibuf: pointer to input packet data
542 * @icnt: length of input data.
543 */
544static void z_incomp(void *arg, unsigned char *ibuf, int icnt)
545{
546 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
547 int proto, r;
548
549 /*
550 * Check that the protocol is one we handle.
551 */
552 proto = PPP_PROTOCOL(ibuf);
553 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
554 return;
555
556 ++state->seqno;
557
558 /*
559 * We start at the either the 1st or 2nd byte of the protocol field,
560 * depending on whether the protocol value is compressible.
561 */
562 state->strm.next_in = ibuf + 3;
563 state->strm.avail_in = icnt - 3;
564 if (proto > 0xff) {
565 --state->strm.next_in;
566 ++state->strm.avail_in;
567 }
568
569 r = zlib_inflateIncomp(&state->strm);
570 if (r != Z_OK) {
571 /* gak! */
572 if (state->debug) {
573 printk(KERN_DEBUG "z_incomp%d: inflateIncomp returned %d (%s)\n",
574 state->unit, r, (state->strm.msg? state->strm.msg: ""));
575 }
576 return;
577 }
578
579 /*
580 * Update stats.
581 */
582 state->stats.inc_bytes += icnt;
583 state->stats.inc_packets++;
584 state->stats.unc_bytes += icnt;
585 state->stats.unc_packets++;
586}
587
588/*************************************************************
589 * Module interface table
590 *************************************************************/
591
592/* These are in ppp_generic.c */
593extern int ppp_register_compressor (struct compressor *cp);
594extern void ppp_unregister_compressor (struct compressor *cp);
595
596/*
597 * Procedures exported to if_ppp.c.
598 */
599static struct compressor ppp_deflate = {
600 .compress_proto = CI_DEFLATE,
601 .comp_alloc = z_comp_alloc,
602 .comp_free = z_comp_free,
603 .comp_init = z_comp_init,
604 .comp_reset = z_comp_reset,
605 .compress = z_compress,
606 .comp_stat = z_comp_stats,
607 .decomp_alloc = z_decomp_alloc,
608 .decomp_free = z_decomp_free,
609 .decomp_init = z_decomp_init,
610 .decomp_reset = z_decomp_reset,
611 .decompress = z_decompress,
612 .incomp = z_incomp,
613 .decomp_stat = z_comp_stats,
614 .owner = THIS_MODULE
615};
616
617static struct compressor ppp_deflate_draft = {
618 .compress_proto = CI_DEFLATE_DRAFT,
619 .comp_alloc = z_comp_alloc,
620 .comp_free = z_comp_free,
621 .comp_init = z_comp_init,
622 .comp_reset = z_comp_reset,
623 .compress = z_compress,
624 .comp_stat = z_comp_stats,
625 .decomp_alloc = z_decomp_alloc,
626 .decomp_free = z_decomp_free,
627 .decomp_init = z_decomp_init,
628 .decomp_reset = z_decomp_reset,
629 .decompress = z_decompress,
630 .incomp = z_incomp,
631 .decomp_stat = z_comp_stats,
632 .owner = THIS_MODULE
633};
634
635static int __init deflate_init(void)
6aa20a22 636{
1da177e4
LT
637 int answer = ppp_register_compressor(&ppp_deflate);
638 if (answer == 0)
639 printk(KERN_INFO
640 "PPP Deflate Compression module registered\n");
641 ppp_register_compressor(&ppp_deflate_draft);
642 return answer;
643}
6aa20a22 644
1da177e4
LT
645static void __exit deflate_cleanup(void)
646{
647 ppp_unregister_compressor(&ppp_deflate);
648 ppp_unregister_compressor(&ppp_deflate_draft);
649}
650
651module_init(deflate_init);
652module_exit(deflate_cleanup);
653MODULE_LICENSE("Dual BSD/GPL");
654MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE));
655MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE_DRAFT));