2 * ppp_deflate.c - interface the zlib procedures for Deflate compression
3 * and decompression (as used by gzip) to the PPP code.
5 * Copyright 1994-1998 Paul Mackerras.
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * version 2 as published by the Free Software Foundation.
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/vmalloc.h>
15 #include <linux/init.h>
16 #include <linux/string.h>
18 #include <linux/ppp_defs.h>
19 #include <linux/ppp-comp.h>
21 #include <linux/zlib.h>
22 #include <asm/unaligned.h>
25 * State for a Deflate (de)compressor.
27 struct ppp_deflate_state {
34 struct compstat stats;
37 #define DEFLATE_OVHD 2 /* Deflate overhead/packet */
39 static void *z_comp_alloc(unsigned char *options, int opt_len);
40 static void *z_decomp_alloc(unsigned char *options, int opt_len);
41 static void z_comp_free(void *state);
42 static void z_decomp_free(void *state);
43 static int z_comp_init(void *state, unsigned char *options,
45 int unit, int hdrlen, int debug);
46 static int z_decomp_init(void *state, unsigned char *options,
48 int unit, int hdrlen, int mru, int debug);
49 static int z_compress(void *state, unsigned char *rptr,
51 int isize, int osize);
52 static void z_incomp(void *state, unsigned char *ibuf, int icnt);
53 static int z_decompress(void *state, unsigned char *ibuf,
54 int isize, unsigned char *obuf, int osize);
55 static void z_comp_reset(void *state);
56 static void z_decomp_reset(void *state);
57 static void z_comp_stats(void *state, struct compstat *stats);
60 * z_comp_free - free the memory used by a compressor
61 * @arg: pointer to the private state for the compressor.
63 static void z_comp_free(void *arg)
65 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
68 zlib_deflateEnd(&state->strm);
69 vfree(state->strm.workspace);
75 * z_comp_alloc - allocate space for a compressor.
76 * @options: pointer to CCP option data
77 * @opt_len: length of the CCP option at @options.
79 * The @options pointer points to the a buffer containing the
80 * CCP option data for the compression being negotiated. It is
81 * formatted according to RFC1979, and describes the window
82 * size that the peer is requesting that we use in compressing
83 * data to be sent to it.
85 * Returns the pointer to the private state for the compressor,
86 * or NULL if we could not allocate enough memory.
88 static void *z_comp_alloc(unsigned char *options, int opt_len)
90 struct ppp_deflate_state *state;
93 if (opt_len != CILEN_DEFLATE ||
94 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
95 options[1] != CILEN_DEFLATE ||
96 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
97 options[3] != DEFLATE_CHK_SEQUENCE)
99 w_size = DEFLATE_SIZE(options[2]);
100 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
103 state = kzalloc(sizeof(*state),
108 state->strm.next_in = NULL;
109 state->w_size = w_size;
110 state->strm.workspace = vmalloc(zlib_deflate_workspacesize(-w_size, 8));
111 if (state->strm.workspace == NULL)
114 if (zlib_deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION,
115 DEFLATE_METHOD_VAL, -w_size, 8, Z_DEFAULT_STRATEGY)
118 return (void *) state;
126 * z_comp_init - initialize a previously-allocated compressor.
127 * @arg: pointer to the private state for the compressor
128 * @options: pointer to the CCP option data describing the
129 * compression that was negotiated with the peer
130 * @opt_len: length of the CCP option data at @options
131 * @unit: PPP unit number for diagnostic messages
132 * @hdrlen: ignored (present for backwards compatibility)
133 * @debug: debug flag; if non-zero, debug messages are printed.
135 * The CCP options described by @options must match the options
136 * specified when the compressor was allocated. The compressor
137 * history is reset. Returns 0 for failure (CCP options don't
138 * match) or 1 for success.
140 static int z_comp_init(void *arg, unsigned char *options, int opt_len,
141 int unit, int hdrlen, int debug)
143 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
145 if (opt_len < CILEN_DEFLATE ||
146 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
147 options[1] != CILEN_DEFLATE ||
148 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
149 DEFLATE_SIZE(options[2]) != state->w_size ||
150 options[3] != DEFLATE_CHK_SEQUENCE)
155 state->debug = debug;
157 zlib_deflateReset(&state->strm);
163 * z_comp_reset - reset a previously-allocated compressor.
164 * @arg: pointer to private state for the compressor.
166 * This clears the history for the compressor and makes it
167 * ready to start emitting a new compressed stream.
169 static void z_comp_reset(void *arg)
171 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
174 zlib_deflateReset(&state->strm);
178 * z_compress - compress a PPP packet with Deflate compression.
179 * @arg: pointer to private state for the compressor
180 * @rptr: uncompressed packet (input)
181 * @obuf: compressed packet (output)
182 * @isize: size of uncompressed packet
183 * @osize: space available at @obuf
185 * Returns the length of the compressed packet, or 0 if the
186 * packet is incompressible.
188 static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,
189 int isize, int osize)
191 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
192 int r, proto, off, olen, oavail;
196 * Check that the protocol is in the range we handle.
198 proto = PPP_PROTOCOL(rptr);
199 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
202 /* Don't generate compressed packets which are larger than
203 the uncompressed packet. */
210 * Copy over the PPP header and store the 2-byte sequence number.
212 wptr[0] = PPP_ADDRESS(rptr);
213 wptr[1] = PPP_CONTROL(rptr);
214 put_unaligned_be16(PPP_COMP, wptr + 2);
216 put_unaligned_be16(state->seqno, wptr);
217 wptr += DEFLATE_OVHD;
218 olen = PPP_HDRLEN + DEFLATE_OVHD;
219 state->strm.next_out = wptr;
220 state->strm.avail_out = oavail = osize - olen;
223 off = (proto > 0xff) ? 2 : 3; /* skip 1st proto byte if 0 */
225 state->strm.next_in = rptr;
226 state->strm.avail_in = (isize - off);
229 r = zlib_deflate(&state->strm, Z_PACKET_FLUSH);
233 "z_compress: deflate returned %d\n", r);
236 if (state->strm.avail_out == 0) {
238 state->strm.next_out = NULL;
239 state->strm.avail_out = oavail = 1000000;
241 break; /* all done */
244 olen += oavail - state->strm.avail_out;
247 * See if we managed to reduce the size of the packet.
250 state->stats.comp_bytes += olen;
251 state->stats.comp_packets++;
253 state->stats.inc_bytes += isize;
254 state->stats.inc_packets++;
257 state->stats.unc_bytes += isize;
258 state->stats.unc_packets++;
264 * z_comp_stats - return compression statistics for a compressor
266 * @arg: pointer to private space for the (de)compressor
267 * @stats: pointer to a struct compstat to receive the result.
269 static void z_comp_stats(void *arg, struct compstat *stats)
271 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
273 *stats = state->stats;
277 * z_decomp_free - Free the memory used by a decompressor.
278 * @arg: pointer to private space for the decompressor.
280 static void z_decomp_free(void *arg)
282 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
285 zlib_inflateEnd(&state->strm);
286 vfree(state->strm.workspace);
292 * z_decomp_alloc - allocate space for a decompressor.
293 * @options: pointer to CCP option data
294 * @opt_len: length of the CCP option at @options.
296 * The @options pointer points to the a buffer containing the
297 * CCP option data for the compression being negotiated. It is
298 * formatted according to RFC1979, and describes the window
299 * size that we are requesting the peer to use in compressing
300 * data to be sent to us.
302 * Returns the pointer to the private state for the decompressor,
303 * or NULL if we could not allocate enough memory.
305 static void *z_decomp_alloc(unsigned char *options, int opt_len)
307 struct ppp_deflate_state *state;
310 if (opt_len != CILEN_DEFLATE ||
311 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
312 options[1] != CILEN_DEFLATE ||
313 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
314 options[3] != DEFLATE_CHK_SEQUENCE)
316 w_size = DEFLATE_SIZE(options[2]);
317 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
320 state = kzalloc(sizeof(*state), GFP_KERNEL);
324 state->w_size = w_size;
325 state->strm.next_out = NULL;
326 state->strm.workspace = vmalloc(zlib_inflate_workspacesize());
327 if (state->strm.workspace == NULL)
330 if (zlib_inflateInit2(&state->strm, -w_size) != Z_OK)
332 return (void *) state;
335 z_decomp_free(state);
340 * z_decomp_init - initialize a previously-allocated decompressor.
341 * @arg: pointer to the private state for the decompressor
342 * @options: pointer to the CCP option data describing the
343 * compression that was negotiated with the peer
344 * @opt_len: length of the CCP option data at @options
345 * @unit: PPP unit number for diagnostic messages
346 * @hdrlen: ignored (present for backwards compatibility)
347 * @mru: maximum length of decompressed packets
348 * @debug: debug flag; if non-zero, debug messages are printed.
350 * The CCP options described by @options must match the options
351 * specified when the decompressor was allocated. The decompressor
352 * history is reset. Returns 0 for failure (CCP options don't
353 * match) or 1 for success.
355 static int z_decomp_init(void *arg, unsigned char *options, int opt_len,
356 int unit, int hdrlen, int mru, int debug)
358 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
360 if (opt_len < CILEN_DEFLATE ||
361 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
362 options[1] != CILEN_DEFLATE ||
363 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
364 DEFLATE_SIZE(options[2]) != state->w_size ||
365 options[3] != DEFLATE_CHK_SEQUENCE)
370 state->debug = debug;
373 zlib_inflateReset(&state->strm);
379 * z_decomp_reset - reset a previously-allocated decompressor.
380 * @arg: pointer to private state for the decompressor.
382 * This clears the history for the decompressor and makes it
383 * ready to receive a new compressed stream.
385 static void z_decomp_reset(void *arg)
387 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
390 zlib_inflateReset(&state->strm);
394 * z_decompress - decompress a Deflate-compressed packet.
395 * @arg: pointer to private state for the decompressor
396 * @ibuf: pointer to input (compressed) packet data
397 * @isize: length of input packet
398 * @obuf: pointer to space for output (decompressed) packet
399 * @osize: amount of space available at @obuf
401 * Because of patent problems, we return DECOMP_ERROR for errors
402 * found by inspecting the input data and for system problems, but
403 * DECOMP_FATALERROR for any errors which could possibly be said to
404 * be being detected "after" decompression. For DECOMP_ERROR,
405 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
406 * infringing a patent of Motorola's if we do, so we take CCP down
409 * Given that the frame has the correct sequence number and a good FCS,
410 * errors such as invalid codes in the input most likely indicate a
411 * bug, so we return DECOMP_FATALERROR for them in order to turn off
412 * compression, even though they are detected by inspecting the input.
414 static int z_decompress(void *arg, unsigned char *ibuf, int isize,
415 unsigned char *obuf, int osize)
417 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
419 int decode_proto, overflow;
420 unsigned char overflow_buf[1];
422 if (isize <= PPP_HDRLEN + DEFLATE_OVHD) {
424 printk(KERN_DEBUG "z_decompress%d: short pkt (%d)\n",
429 /* Check the sequence number. */
430 seq = get_unaligned_be16(ibuf + PPP_HDRLEN);
431 if (seq != (state->seqno & 0xffff)) {
433 printk(KERN_DEBUG "z_decompress%d: bad seq # %d, expected %d\n",
434 state->unit, seq, state->seqno & 0xffff);
440 * Fill in the first part of the PPP header. The protocol field
441 * comes from the decompressed data.
443 obuf[0] = PPP_ADDRESS(ibuf);
444 obuf[1] = PPP_CONTROL(ibuf);
448 * Set up to call inflate. We set avail_out to 1 initially so we can
449 * look at the first byte of the output and decide whether we have
450 * a 1-byte or 2-byte protocol field.
452 state->strm.next_in = ibuf + PPP_HDRLEN + DEFLATE_OVHD;
453 state->strm.avail_in = isize - (PPP_HDRLEN + DEFLATE_OVHD);
454 state->strm.next_out = obuf + 3;
455 state->strm.avail_out = 1;
460 * Call inflate, supplying more input or output as needed.
463 r = zlib_inflate(&state->strm, Z_PACKET_FLUSH);
466 printk(KERN_DEBUG "z_decompress%d: inflate returned %d (%s)\n",
467 state->unit, r, (state->strm.msg? state->strm.msg: ""));
468 return DECOMP_FATALERROR;
470 if (state->strm.avail_out != 0)
471 break; /* all done */
473 state->strm.avail_out = osize - PPP_HDRLEN;
474 if ((obuf[3] & 1) == 0) {
475 /* 2-byte protocol field */
477 --state->strm.next_out;
478 ++state->strm.avail_out;
481 } else if (!overflow) {
483 * We've filled up the output buffer; the only way to
484 * find out whether inflate has any more characters
485 * left is to give it another byte of output space.
487 state->strm.next_out = overflow_buf;
488 state->strm.avail_out = 1;
492 printk(KERN_DEBUG "z_decompress%d: ran out of mru\n",
494 return DECOMP_FATALERROR;
500 printk(KERN_DEBUG "z_decompress%d: didn't get proto\n",
505 olen = osize + overflow - state->strm.avail_out;
506 state->stats.unc_bytes += olen;
507 state->stats.unc_packets++;
508 state->stats.comp_bytes += isize;
509 state->stats.comp_packets++;
515 * z_incomp - add incompressible input data to the history.
516 * @arg: pointer to private state for the decompressor
517 * @ibuf: pointer to input packet data
518 * @icnt: length of input data.
520 static void z_incomp(void *arg, unsigned char *ibuf, int icnt)
522 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
526 * Check that the protocol is one we handle.
528 proto = PPP_PROTOCOL(ibuf);
529 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
535 * We start at the either the 1st or 2nd byte of the protocol field,
536 * depending on whether the protocol value is compressible.
538 state->strm.next_in = ibuf + 3;
539 state->strm.avail_in = icnt - 3;
541 --state->strm.next_in;
542 ++state->strm.avail_in;
545 r = zlib_inflateIncomp(&state->strm);
549 printk(KERN_DEBUG "z_incomp%d: inflateIncomp returned %d (%s)\n",
550 state->unit, r, (state->strm.msg? state->strm.msg: ""));
558 state->stats.inc_bytes += icnt;
559 state->stats.inc_packets++;
560 state->stats.unc_bytes += icnt;
561 state->stats.unc_packets++;
564 /*************************************************************
565 * Module interface table
566 *************************************************************/
568 /* These are in ppp_generic.c */
569 extern int ppp_register_compressor (struct compressor *cp);
570 extern void ppp_unregister_compressor (struct compressor *cp);
573 * Procedures exported to if_ppp.c.
575 static struct compressor ppp_deflate = {
576 .compress_proto = CI_DEFLATE,
577 .comp_alloc = z_comp_alloc,
578 .comp_free = z_comp_free,
579 .comp_init = z_comp_init,
580 .comp_reset = z_comp_reset,
581 .compress = z_compress,
582 .comp_stat = z_comp_stats,
583 .decomp_alloc = z_decomp_alloc,
584 .decomp_free = z_decomp_free,
585 .decomp_init = z_decomp_init,
586 .decomp_reset = z_decomp_reset,
587 .decompress = z_decompress,
589 .decomp_stat = z_comp_stats,
593 static struct compressor ppp_deflate_draft = {
594 .compress_proto = CI_DEFLATE_DRAFT,
595 .comp_alloc = z_comp_alloc,
596 .comp_free = z_comp_free,
597 .comp_init = z_comp_init,
598 .comp_reset = z_comp_reset,
599 .compress = z_compress,
600 .comp_stat = z_comp_stats,
601 .decomp_alloc = z_decomp_alloc,
602 .decomp_free = z_decomp_free,
603 .decomp_init = z_decomp_init,
604 .decomp_reset = z_decomp_reset,
605 .decompress = z_decompress,
607 .decomp_stat = z_comp_stats,
611 static int __init deflate_init(void)
613 int answer = ppp_register_compressor(&ppp_deflate);
616 "PPP Deflate Compression module registered\n");
617 ppp_register_compressor(&ppp_deflate_draft);
621 static void __exit deflate_cleanup(void)
623 ppp_unregister_compressor(&ppp_deflate);
624 ppp_unregister_compressor(&ppp_deflate_draft);
627 module_init(deflate_init);
628 module_exit(deflate_cleanup);
629 MODULE_LICENSE("Dual BSD/GPL");
630 MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE));
631 MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE_DRAFT));