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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#include <asm/unaligned.h>
45
46/*
47 * State for a Deflate (de)compressor.
48 */
49struct ppp_deflate_state {
50 int seqno;
51 int w_size;
52 int unit;
53 int mru;
54 int debug;
55 z_stream strm;
56 struct compstat stats;
57};
58
59#define DEFLATE_OVHD 2 /* Deflate overhead/packet */
60
61static void *z_comp_alloc(unsigned char *options, int opt_len);
62static void *z_decomp_alloc(unsigned char *options, int opt_len);
63static void z_comp_free(void *state);
64static void z_decomp_free(void *state);
65static int z_comp_init(void *state, unsigned char *options,
66 int opt_len,
67 int unit, int hdrlen, int debug);
68static int z_decomp_init(void *state, unsigned char *options,
69 int opt_len,
70 int unit, int hdrlen, int mru, int debug);
71static int z_compress(void *state, unsigned char *rptr,
72 unsigned char *obuf,
73 int isize, int osize);
74static void z_incomp(void *state, unsigned char *ibuf, int icnt);
75static int z_decompress(void *state, unsigned char *ibuf,
76 int isize, unsigned char *obuf, int osize);
77static void z_comp_reset(void *state);
78static void z_decomp_reset(void *state);
79static void z_comp_stats(void *state, struct compstat *stats);
80
81/**
82 * z_comp_free - free the memory used by a compressor
83 * @arg: pointer to the private state for the compressor.
84 */
85static void z_comp_free(void *arg)
86{
87 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
88
89 if (state) {
90 zlib_deflateEnd(&state->strm);
91 vfree(state->strm.workspace);
92 kfree(state);
93 }
94}
95
96/**
97 * z_comp_alloc - allocate space for a compressor.
98 * @options: pointer to CCP option data
99 * @opt_len: length of the CCP option at @options.
100 *
101 * The @options pointer points to the a buffer containing the
102 * CCP option data for the compression being negotiated. It is
103 * formatted according to RFC1979, and describes the window
104 * size that the peer is requesting that we use in compressing
105 * data to be sent to it.
106 *
107 * Returns the pointer to the private state for the compressor,
108 * or NULL if we could not allocate enough memory.
109 */
110static void *z_comp_alloc(unsigned char *options, int opt_len)
111{
112 struct ppp_deflate_state *state;
113 int w_size;
114
115 if (opt_len != CILEN_DEFLATE ||
116 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
117 options[1] != CILEN_DEFLATE ||
118 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
119 options[3] != DEFLATE_CHK_SEQUENCE)
120 return NULL;
121 w_size = DEFLATE_SIZE(options[2]);
122 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
123 return NULL;
124
125 state = kzalloc(sizeof(*state),
126 GFP_KERNEL);
127 if (state == NULL)
128 return NULL;
129
130 state->strm.next_in = NULL;
131 state->w_size = w_size;
132 state->strm.workspace = vmalloc(zlib_deflate_workspacesize(-w_size, 8));
133 if (state->strm.workspace == NULL)
134 goto out_free;
135
136 if (zlib_deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION,
137 DEFLATE_METHOD_VAL, -w_size, 8, Z_DEFAULT_STRATEGY)
138 != Z_OK)
139 goto out_free;
140 return (void *) state;
141
142out_free:
143 z_comp_free(state);
144 return NULL;
145}
146
147/**
148 * z_comp_init - initialize a previously-allocated compressor.
149 * @arg: pointer to the private state for the compressor
150 * @options: pointer to the CCP option data describing the
151 * compression that was negotiated with the peer
152 * @opt_len: length of the CCP option data at @options
153 * @unit: PPP unit number for diagnostic messages
154 * @hdrlen: ignored (present for backwards compatibility)
155 * @debug: debug flag; if non-zero, debug messages are printed.
156 *
157 * The CCP options described by @options must match the options
158 * specified when the compressor was allocated. The compressor
159 * history is reset. Returns 0 for failure (CCP options don't
160 * match) or 1 for success.
161 */
162static int z_comp_init(void *arg, unsigned char *options, int opt_len,
163 int unit, int hdrlen, int debug)
164{
165 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
166
167 if (opt_len < CILEN_DEFLATE ||
168 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
169 options[1] != CILEN_DEFLATE ||
170 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
171 DEFLATE_SIZE(options[2]) != state->w_size ||
172 options[3] != DEFLATE_CHK_SEQUENCE)
173 return 0;
174
175 state->seqno = 0;
176 state->unit = unit;
177 state->debug = debug;
178
179 zlib_deflateReset(&state->strm);
180
181 return 1;
182}
183
184/**
185 * z_comp_reset - reset a previously-allocated compressor.
186 * @arg: pointer to private state for the compressor.
187 *
188 * This clears the history for the compressor and makes it
189 * ready to start emitting a new compressed stream.
190 */
191static void z_comp_reset(void *arg)
192{
193 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
194
195 state->seqno = 0;
196 zlib_deflateReset(&state->strm);
197}
198
199/**
200 * z_compress - compress a PPP packet with Deflate compression.
201 * @arg: pointer to private state for the compressor
202 * @rptr: uncompressed packet (input)
203 * @obuf: compressed packet (output)
204 * @isize: size of uncompressed packet
205 * @osize: space available at @obuf
206 *
207 * Returns the length of the compressed packet, or 0 if the
208 * packet is incompressible.
209 */
210static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,
211 int isize, int osize)
212{
213 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
214 int r, proto, off, olen, oavail;
215 unsigned char *wptr;
216
217 /*
218 * Check that the protocol is in the range we handle.
219 */
220 proto = PPP_PROTOCOL(rptr);
221 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
222 return 0;
223
224 /* Don't generate compressed packets which are larger than
225 the uncompressed packet. */
226 if (osize > isize)
227 osize = isize;
228
229 wptr = obuf;
230
231 /*
232 * Copy over the PPP header and store the 2-byte sequence number.
233 */
234 wptr[0] = PPP_ADDRESS(rptr);
235 wptr[1] = PPP_CONTROL(rptr);
236 put_unaligned_be16(PPP_COMP, wptr + 2);
237 wptr += PPP_HDRLEN;
238 put_unaligned_be16(state->seqno, wptr);
239 wptr += DEFLATE_OVHD;
240 olen = PPP_HDRLEN + DEFLATE_OVHD;
241 state->strm.next_out = wptr;
242 state->strm.avail_out = oavail = osize - olen;
243 ++state->seqno;
244
245 off = (proto > 0xff) ? 2 : 3; /* skip 1st proto byte if 0 */
246 rptr += off;
247 state->strm.next_in = rptr;
248 state->strm.avail_in = (isize - off);
249
250 for (;;) {
251 r = zlib_deflate(&state->strm, Z_PACKET_FLUSH);
252 if (r != Z_OK) {
253 if (state->debug)
254 printk(KERN_ERR
255 "z_compress: deflate returned %d\n", r);
256 break;
257 }
258 if (state->strm.avail_out == 0) {
259 olen += oavail;
260 state->strm.next_out = NULL;
261 state->strm.avail_out = oavail = 1000000;
262 } else {
263 break; /* all done */
264 }
265 }
266 olen += oavail - state->strm.avail_out;
267
268 /*
269 * See if we managed to reduce the size of the packet.
270 */
271 if (olen < isize) {
272 state->stats.comp_bytes += olen;
273 state->stats.comp_packets++;
274 } else {
275 state->stats.inc_bytes += isize;
276 state->stats.inc_packets++;
277 olen = 0;
278 }
279 state->stats.unc_bytes += isize;
280 state->stats.unc_packets++;
281
282 return olen;
283}
284
285/**
286 * z_comp_stats - return compression statistics for a compressor
287 * or decompressor.
288 * @arg: pointer to private space for the (de)compressor
289 * @stats: pointer to a struct compstat to receive the result.
290 */
291static void z_comp_stats(void *arg, struct compstat *stats)
292{
293 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
294
295 *stats = state->stats;
296}
297
298/**
299 * z_decomp_free - Free the memory used by a decompressor.
300 * @arg: pointer to private space for the decompressor.
301 */
302static void z_decomp_free(void *arg)
303{
304 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
305
306 if (state) {
307 zlib_inflateEnd(&state->strm);
308 vfree(state->strm.workspace);
309 kfree(state);
310 }
311}
312
313/**
314 * z_decomp_alloc - allocate space for a decompressor.
315 * @options: pointer to CCP option data
316 * @opt_len: length of the CCP option at @options.
317 *
318 * The @options pointer points to the a buffer containing the
319 * CCP option data for the compression being negotiated. It is
320 * formatted according to RFC1979, and describes the window
321 * size that we are requesting the peer to use in compressing
322 * data to be sent to us.
323 *
324 * Returns the pointer to the private state for the decompressor,
325 * or NULL if we could not allocate enough memory.
326 */
327static void *z_decomp_alloc(unsigned char *options, int opt_len)
328{
329 struct ppp_deflate_state *state;
330 int w_size;
331
332 if (opt_len != CILEN_DEFLATE ||
333 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
334 options[1] != CILEN_DEFLATE ||
335 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
336 options[3] != DEFLATE_CHK_SEQUENCE)
337 return NULL;
338 w_size = DEFLATE_SIZE(options[2]);
339 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
340 return NULL;
341
342 state = kzalloc(sizeof(*state), GFP_KERNEL);
343 if (state == NULL)
344 return NULL;
345
346 state->w_size = w_size;
347 state->strm.next_out = NULL;
348 state->strm.workspace = vmalloc(zlib_inflate_workspacesize());
349 if (state->strm.workspace == NULL)
350 goto out_free;
351
352 if (zlib_inflateInit2(&state->strm, -w_size) != Z_OK)
353 goto out_free;
354 return (void *) state;
355
356out_free:
357 z_decomp_free(state);
358 return NULL;
359}
360
361/**
362 * z_decomp_init - initialize a previously-allocated decompressor.
363 * @arg: pointer to the private state for the decompressor
364 * @options: pointer to the CCP option data describing the
365 * compression that was negotiated with the peer
366 * @opt_len: length of the CCP option data at @options
367 * @unit: PPP unit number for diagnostic messages
368 * @hdrlen: ignored (present for backwards compatibility)
369 * @mru: maximum length of decompressed packets
370 * @debug: debug flag; if non-zero, debug messages are printed.
371 *
372 * The CCP options described by @options must match the options
373 * specified when the decompressor was allocated. The decompressor
374 * history is reset. Returns 0 for failure (CCP options don't
375 * match) or 1 for success.
376 */
377static int z_decomp_init(void *arg, unsigned char *options, int opt_len,
378 int unit, int hdrlen, int mru, int debug)
379{
380 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
381
382 if (opt_len < CILEN_DEFLATE ||
383 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
384 options[1] != CILEN_DEFLATE ||
385 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
386 DEFLATE_SIZE(options[2]) != state->w_size ||
387 options[3] != DEFLATE_CHK_SEQUENCE)
388 return 0;
389
390 state->seqno = 0;
391 state->unit = unit;
392 state->debug = debug;
393 state->mru = mru;
394
395 zlib_inflateReset(&state->strm);
396
397 return 1;
398}
399
400/**
401 * z_decomp_reset - reset a previously-allocated decompressor.
402 * @arg: pointer to private state for the decompressor.
403 *
404 * This clears the history for the decompressor and makes it
405 * ready to receive a new compressed stream.
406 */
407static void z_decomp_reset(void *arg)
408{
409 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
410
411 state->seqno = 0;
412 zlib_inflateReset(&state->strm);
413}
414
415/**
416 * z_decompress - decompress a Deflate-compressed packet.
417 * @arg: pointer to private state for the decompressor
418 * @ibuf: pointer to input (compressed) packet data
419 * @isize: length of input packet
420 * @obuf: pointer to space for output (decompressed) packet
421 * @osize: amount of space available at @obuf
422 *
423 * Because of patent problems, we return DECOMP_ERROR for errors
424 * found by inspecting the input data and for system problems, but
425 * DECOMP_FATALERROR for any errors which could possibly be said to
426 * be being detected "after" decompression. For DECOMP_ERROR,
427 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
428 * infringing a patent of Motorola's if we do, so we take CCP down
429 * instead.
430 *
431 * Given that the frame has the correct sequence number and a good FCS,
432 * errors such as invalid codes in the input most likely indicate a
433 * bug, so we return DECOMP_FATALERROR for them in order to turn off
434 * compression, even though they are detected by inspecting the input.
435 */
436static int z_decompress(void *arg, unsigned char *ibuf, int isize,
437 unsigned char *obuf, int osize)
438{
439 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
440 int olen, seq, r;
441 int decode_proto, overflow;
442 unsigned char overflow_buf[1];
443
444 if (isize <= PPP_HDRLEN + DEFLATE_OVHD) {
445 if (state->debug)
446 printk(KERN_DEBUG "z_decompress%d: short pkt (%d)\n",
447 state->unit, isize);
448 return DECOMP_ERROR;
449 }
450
451 /* Check the sequence number. */
452 seq = get_unaligned_be16(ibuf + PPP_HDRLEN);
453 if (seq != (state->seqno & 0xffff)) {
454 if (state->debug)
455 printk(KERN_DEBUG "z_decompress%d: bad seq # %d, expected %d\n",
456 state->unit, seq, state->seqno & 0xffff);
457 return DECOMP_ERROR;
458 }
459 ++state->seqno;
460
461 /*
462 * Fill in the first part of the PPP header. The protocol field
463 * comes from the decompressed data.
464 */
465 obuf[0] = PPP_ADDRESS(ibuf);
466 obuf[1] = PPP_CONTROL(ibuf);
467 obuf[2] = 0;
468
469 /*
470 * Set up to call inflate. We set avail_out to 1 initially so we can
471 * look at the first byte of the output and decide whether we have
472 * a 1-byte or 2-byte protocol field.
473 */
474 state->strm.next_in = ibuf + PPP_HDRLEN + DEFLATE_OVHD;
475 state->strm.avail_in = isize - (PPP_HDRLEN + DEFLATE_OVHD);
476 state->strm.next_out = obuf + 3;
477 state->strm.avail_out = 1;
478 decode_proto = 1;
479 overflow = 0;
480
481 /*
482 * Call inflate, supplying more input or output as needed.
483 */
484 for (;;) {
485 r = zlib_inflate(&state->strm, Z_PACKET_FLUSH);
486 if (r != Z_OK) {
487 if (state->debug)
488 printk(KERN_DEBUG "z_decompress%d: inflate returned %d (%s)\n",
489 state->unit, r, (state->strm.msg? state->strm.msg: ""));
490 return DECOMP_FATALERROR;
491 }
492 if (state->strm.avail_out != 0)
493 break; /* all done */
494 if (decode_proto) {
495 state->strm.avail_out = osize - PPP_HDRLEN;
496 if ((obuf[3] & 1) == 0) {
497 /* 2-byte protocol field */
498 obuf[2] = obuf[3];
499 --state->strm.next_out;
500 ++state->strm.avail_out;
501 }
502 decode_proto = 0;
503 } else if (!overflow) {
504 /*
505 * We've filled up the output buffer; the only way to
506 * find out whether inflate has any more characters
507 * left is to give it another byte of output space.
508 */
509 state->strm.next_out = overflow_buf;
510 state->strm.avail_out = 1;
511 overflow = 1;
512 } else {
513 if (state->debug)
514 printk(KERN_DEBUG "z_decompress%d: ran out of mru\n",
515 state->unit);
516 return DECOMP_FATALERROR;
517 }
518 }
519
520 if (decode_proto) {
521 if (state->debug)
522 printk(KERN_DEBUG "z_decompress%d: didn't get proto\n",
523 state->unit);
524 return DECOMP_ERROR;
525 }
526
527 olen = osize + overflow - state->strm.avail_out;
528 state->stats.unc_bytes += olen;
529 state->stats.unc_packets++;
530 state->stats.comp_bytes += isize;
531 state->stats.comp_packets++;
532
533 return olen;
534}
535
536/**
537 * z_incomp - add incompressible input data to the history.
538 * @arg: pointer to private state for the decompressor
539 * @ibuf: pointer to input packet data
540 * @icnt: length of input data.
541 */
542static void z_incomp(void *arg, unsigned char *ibuf, int icnt)
543{
544 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
545 int proto, r;
546
547 /*
548 * Check that the protocol is one we handle.
549 */
550 proto = PPP_PROTOCOL(ibuf);
551 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
552 return;
553
554 ++state->seqno;
555
556 /*
557 * We start at the either the 1st or 2nd byte of the protocol field,
558 * depending on whether the protocol value is compressible.
559 */
560 state->strm.next_in = ibuf + 3;
561 state->strm.avail_in = icnt - 3;
562 if (proto > 0xff) {
563 --state->strm.next_in;
564 ++state->strm.avail_in;
565 }
566
567 r = zlib_inflateIncomp(&state->strm);
568 if (r != Z_OK) {
569 /* gak! */
570 if (state->debug) {
571 printk(KERN_DEBUG "z_incomp%d: inflateIncomp returned %d (%s)\n",
572 state->unit, r, (state->strm.msg? state->strm.msg: ""));
573 }
574 return;
575 }
576
577 /*
578 * Update stats.
579 */
580 state->stats.inc_bytes += icnt;
581 state->stats.inc_packets++;
582 state->stats.unc_bytes += icnt;
583 state->stats.unc_packets++;
584}
585
586/*************************************************************
587 * Module interface table
588 *************************************************************/
589
590/* These are in ppp_generic.c */
591extern int ppp_register_compressor (struct compressor *cp);
592extern void ppp_unregister_compressor (struct compressor *cp);
593
594/*
595 * Procedures exported to if_ppp.c.
596 */
597static struct compressor ppp_deflate = {
598 .compress_proto = CI_DEFLATE,
599 .comp_alloc = z_comp_alloc,
600 .comp_free = z_comp_free,
601 .comp_init = z_comp_init,
602 .comp_reset = z_comp_reset,
603 .compress = z_compress,
604 .comp_stat = z_comp_stats,
605 .decomp_alloc = z_decomp_alloc,
606 .decomp_free = z_decomp_free,
607 .decomp_init = z_decomp_init,
608 .decomp_reset = z_decomp_reset,
609 .decompress = z_decompress,
610 .incomp = z_incomp,
611 .decomp_stat = z_comp_stats,
612 .owner = THIS_MODULE
613};
614
615static struct compressor ppp_deflate_draft = {
616 .compress_proto = CI_DEFLATE_DRAFT,
617 .comp_alloc = z_comp_alloc,
618 .comp_free = z_comp_free,
619 .comp_init = z_comp_init,
620 .comp_reset = z_comp_reset,
621 .compress = z_compress,
622 .comp_stat = z_comp_stats,
623 .decomp_alloc = z_decomp_alloc,
624 .decomp_free = z_decomp_free,
625 .decomp_init = z_decomp_init,
626 .decomp_reset = z_decomp_reset,
627 .decompress = z_decompress,
628 .incomp = z_incomp,
629 .decomp_stat = z_comp_stats,
630 .owner = THIS_MODULE
631};
632
633static int __init deflate_init(void)
634{
635 int answer = ppp_register_compressor(&ppp_deflate);
636 if (answer == 0)
637 printk(KERN_INFO
638 "PPP Deflate Compression module registered\n");
639 ppp_register_compressor(&ppp_deflate_draft);
640 return answer;
641}
642
643static void __exit deflate_cleanup(void)
644{
645 ppp_unregister_compressor(&ppp_deflate);
646 ppp_unregister_compressor(&ppp_deflate_draft);
647}
648
649module_init(deflate_init);
650module_exit(deflate_cleanup);
651MODULE_LICENSE("Dual BSD/GPL");
652MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE));
653MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE_DRAFT));