xref: /openbsd/sys/net/ppp-deflate.c (revision db3296cf)
1 /*	$OpenBSD: ppp-deflate.c,v 1.7 2002/09/13 00:12:07 deraadt Exp $	*/
2 /*	$NetBSD: ppp-deflate.c,v 1.1 1996/03/15 02:28:09 paulus Exp $	*/
3 
4 /*
5  * ppp_deflate.c - interface the zlib procedures for Deflate compression
6  * and decompression (as used by gzip) to the PPP code.
7  * This version is for use with mbufs on BSD-derived systems.
8  *
9  * Copyright (c) 1989-2002 Paul Mackerras. All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  *
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  *
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in
20  *    the documentation and/or other materials provided with the
21  *    distribution.
22  *
23  * 3. The name(s) of the authors of this software must not be used to
24  *    endorse or promote products derived from this software without
25  *    prior written permission.
26  *
27  * 4. Redistributions of any form whatsoever must retain the following
28  *    acknowledgment:
29  *    "This product includes software developed by Paul Mackerras
30  *     <paulus@samba.org>".
31  *
32  * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
33  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
34  * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
35  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
36  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
37  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
38  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
39  */
40 
41 #include <sys/param.h>
42 #include <sys/types.h>
43 #include <sys/systm.h>
44 #include <sys/mbuf.h>
45 #include <net/ppp_defs.h>
46 #include <net/zlib.h>
47 
48 #define PACKETPTR	struct mbuf *
49 #include <net/ppp-comp.h>
50 
51 #if DO_DEFLATE
52 
53 /*
54  * State for a Deflate (de)compressor.
55  */
56 struct deflate_state {
57     int		seqno;
58     int		w_size;
59     int		unit;
60     int		hdrlen;
61     int		mru;
62     int		debug;
63     z_stream	strm;
64     struct compstat stats;
65 };
66 
67 #define DEFLATE_OVHD	2		/* Deflate overhead/packet */
68 
69 static void	*zalloc(void *, u_int items, u_int size);
70 static void	zfree(void *, void *ptr, u_int nb);
71 static void	*z_comp_alloc(u_char *options, int opt_len);
72 static void	*z_decomp_alloc(u_char *options, int opt_len);
73 static void	z_comp_free(void *state);
74 static void	z_decomp_free(void *state);
75 static int	z_comp_init(void *state, u_char *options, int opt_len,
76 				 int unit, int hdrlen, int debug);
77 static int	z_decomp_init(void *state, u_char *options, int opt_len,
78 				     int unit, int hdrlen, int mru, int debug);
79 static int	z_compress(void *state, struct mbuf **mret,
80 				  struct mbuf *mp, int slen, int maxolen);
81 static void	z_incomp(void *state, struct mbuf *dmsg);
82 static int	z_decompress(void *state, struct mbuf *cmp,
83 				    struct mbuf **dmpp);
84 static void	z_comp_reset(void *state);
85 static void	z_decomp_reset(void *state);
86 static void	z_comp_stats(void *state, struct compstat *stats);
87 
88 /*
89  * Procedures exported to if_ppp.c.
90  */
91 struct compressor ppp_deflate = {
92     CI_DEFLATE,			/* compress_proto */
93     z_comp_alloc,		/* comp_alloc */
94     z_comp_free,		/* comp_free */
95     z_comp_init,		/* comp_init */
96     z_comp_reset,		/* comp_reset */
97     z_compress,			/* compress */
98     z_comp_stats,		/* comp_stat */
99     z_decomp_alloc,		/* decomp_alloc */
100     z_decomp_free,		/* decomp_free */
101     z_decomp_init,		/* decomp_init */
102     z_decomp_reset,		/* decomp_reset */
103     z_decompress,		/* decompress */
104     z_incomp,			/* incomp */
105     z_comp_stats,		/* decomp_stat */
106 };
107 
108 struct compressor ppp_deflate_draft = {
109     CI_DEFLATE_DRAFT,		/* compress_proto */
110     z_comp_alloc,		/* comp_alloc */
111     z_comp_free,		/* comp_free */
112     z_comp_init,		/* comp_init */
113     z_comp_reset,		/* comp_reset */
114     z_compress,			/* compress */
115     z_comp_stats,		/* comp_stat */
116     z_decomp_alloc,		/* decomp_alloc */
117     z_decomp_free,		/* decomp_free */
118     z_decomp_init,		/* decomp_init */
119     z_decomp_reset,		/* decomp_reset */
120     z_decompress,		/* decompress */
121     z_incomp,			/* incomp */
122     z_comp_stats,		/* decomp_stat */
123 };
124 /*
125  * Space allocation and freeing routines for use by zlib routines.
126  */
127 void *
128 zalloc(notused, items, size)
129     void *notused;
130     u_int items, size;
131 {
132     void *ptr;
133 
134     MALLOC(ptr, void *, items * size, M_DEVBUF, M_NOWAIT);
135     return ptr;
136 }
137 
138 void
139 zfree(notused, ptr, nbytes)
140     void *notused;
141     void *ptr;
142     u_int nbytes;
143 {
144     FREE(ptr, M_DEVBUF);
145 }
146 
147 /*
148  * Allocate space for a compressor.
149  */
150 static void *
151 z_comp_alloc(options, opt_len)
152     u_char *options;
153     int opt_len;
154 {
155     struct deflate_state *state;
156     int w_size;
157 
158     if (opt_len != CILEN_DEFLATE
159 	|| (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
160 	|| options[1] != CILEN_DEFLATE
161 	|| DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
162 	|| options[3] != DEFLATE_CHK_SEQUENCE)
163 	return NULL;
164     w_size = DEFLATE_SIZE(options[2]);
165     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
166 	return NULL;
167 
168     MALLOC(state, struct deflate_state *, sizeof(struct deflate_state),
169 	   M_DEVBUF, M_NOWAIT);
170     if (state == NULL)
171 	return NULL;
172 
173     state->strm.next_in = NULL;
174     state->strm.zalloc = zalloc;
175     state->strm.zfree = zfree;
176     if (deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION, DEFLATE_METHOD_VAL,
177 		     -w_size, 8, Z_DEFAULT_STRATEGY, DEFLATE_OVHD+2) != Z_OK) {
178 	FREE(state, M_DEVBUF);
179 	return NULL;
180     }
181 
182     state->w_size = w_size;
183     bzero(&state->stats, sizeof(state->stats));
184     return (void *) state;
185 }
186 
187 static void
188 z_comp_free(arg)
189     void *arg;
190 {
191     struct deflate_state *state = (struct deflate_state *) arg;
192 
193     deflateEnd(&state->strm);
194     FREE(state, M_DEVBUF);
195 }
196 
197 static int
198 z_comp_init(arg, options, opt_len, unit, hdrlen, debug)
199     void *arg;
200     u_char *options;
201     int opt_len, unit, hdrlen, debug;
202 {
203     struct deflate_state *state = (struct deflate_state *) arg;
204 
205     if (opt_len < CILEN_DEFLATE
206 	|| (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
207 	|| options[1] != CILEN_DEFLATE
208 	|| DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
209 	|| DEFLATE_SIZE(options[2]) != state->w_size
210 	|| options[3] != DEFLATE_CHK_SEQUENCE)
211 	return 0;
212 
213     state->seqno = 0;
214     state->unit = unit;
215     state->hdrlen = hdrlen;
216     state->debug = debug;
217 
218     deflateReset(&state->strm);
219 
220     return 1;
221 }
222 
223 static void
224 z_comp_reset(arg)
225     void *arg;
226 {
227     struct deflate_state *state = (struct deflate_state *) arg;
228 
229     state->seqno = 0;
230     deflateReset(&state->strm);
231 }
232 
233 int
234 z_compress(arg, mret, mp, orig_len, maxolen)
235     void *arg;
236     struct mbuf **mret;		/* compressed packet (out) */
237     struct mbuf *mp;		/* uncompressed packet (in) */
238     int orig_len, maxolen;
239 {
240     struct deflate_state *state = (struct deflate_state *) arg;
241     u_char *rptr, *wptr;
242     int proto, olen, wspace, r, flush;
243     struct mbuf *m;
244 
245     /*
246      * Check that the protocol is in the range we handle.
247      */
248     rptr = mtod(mp, u_char *);
249     proto = PPP_PROTOCOL(rptr);
250     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb) {
251 	*mret = NULL;
252 	return orig_len;
253     }
254 
255     /* Allocate one mbuf initially. */
256     if (maxolen > orig_len)
257 	maxolen = orig_len;
258     MGET(m, M_DONTWAIT, MT_DATA);
259     *mret = m;
260     if (m != NULL) {
261 	m->m_len = 0;
262 	if (maxolen + state->hdrlen > MLEN)
263 	    MCLGET(m, M_DONTWAIT);
264 	wspace = M_TRAILINGSPACE(m);
265 	if (state->hdrlen + PPP_HDRLEN + 2 < wspace) {
266 	    m->m_data += state->hdrlen;
267 	    wspace -= state->hdrlen;
268 	}
269 	wptr = mtod(m, u_char *);
270 
271 	/*
272 	 * Copy over the PPP header and store the 2-byte sequence number.
273 	 */
274 	wptr[0] = PPP_ADDRESS(rptr);
275 	wptr[1] = PPP_CONTROL(rptr);
276 	wptr[2] = PPP_COMP >> 8;
277 	wptr[3] = PPP_COMP;
278 	wptr += PPP_HDRLEN;
279 	wptr[0] = state->seqno >> 8;
280 	wptr[1] = state->seqno;
281 	wptr += 2;
282 	state->strm.next_out = wptr;
283 	state->strm.avail_out = wspace - (PPP_HDRLEN + 2);
284     } else {
285 	state->strm.next_out = NULL;
286 	state->strm.avail_out = 1000000;
287 	wptr = NULL;
288 	wspace = 0;
289     }
290     ++state->seqno;
291 
292     rptr += (proto > 0xff)? 2: 3;	/* skip 1st proto byte if 0 */
293     state->strm.next_in = rptr;
294     state->strm.avail_in = mtod(mp, u_char *) + mp->m_len - rptr;
295     mp = mp->m_next;
296     flush = (mp == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
297     olen = 0;
298     for (;;) {
299 	r = deflate(&state->strm, flush);
300 	if (r != Z_OK) {
301 	    printf("z_compress: deflate returned %d (%s)\n",
302 		   r, (state->strm.msg? state->strm.msg: ""));
303 	    break;
304 	}
305 	if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
306 	    break;		/* all done */
307 	if (state->strm.avail_in == 0 && mp != NULL) {
308 	    state->strm.next_in = mtod(mp, u_char *);
309 	    state->strm.avail_in = mp->m_len;
310 	    mp = mp->m_next;
311 	    if (mp == NULL)
312 		flush = Z_PACKET_FLUSH;
313 	}
314 	if (state->strm.avail_out == 0) {
315 	    if (m != NULL) {
316 		m->m_len = wspace;
317 		olen += wspace;
318 		MGET(m->m_next, M_DONTWAIT, MT_DATA);
319 		m = m->m_next;
320 		if (m != NULL) {
321 		    m->m_len = 0;
322 		    if (maxolen - olen > MLEN)
323 			MCLGET(m, M_DONTWAIT);
324 		    state->strm.next_out = mtod(m, u_char *);
325 		    state->strm.avail_out = wspace = M_TRAILINGSPACE(m);
326 		}
327 	    }
328 	    if (m == NULL) {
329 		state->strm.next_out = NULL;
330 		state->strm.avail_out = 1000000;
331 	    }
332 	}
333     }
334     if (m != NULL)
335 	olen += (m->m_len = wspace - state->strm.avail_out);
336 
337     /*
338      * See if we managed to reduce the size of the packet.
339      * If the compressor just gave us a single zero byte, it means
340      * the packet was incompressible.
341      */
342     if (m != NULL && olen < orig_len
343 	&& !(olen == PPP_HDRLEN + 3 && *wptr == 0)) {
344 	state->stats.comp_bytes += olen;
345 	state->stats.comp_packets++;
346     } else {
347 	if (*mret != NULL) {
348 	    m_freem(*mret);
349 	    *mret = NULL;
350 	}
351 	state->stats.inc_bytes += orig_len;
352 	state->stats.inc_packets++;
353 	olen = orig_len;
354     }
355     state->stats.unc_bytes += orig_len;
356     state->stats.unc_packets++;
357 
358     return olen;
359 }
360 
361 static void
362 z_comp_stats(arg, stats)
363     void *arg;
364     struct compstat *stats;
365 {
366     struct deflate_state *state = (struct deflate_state *) arg;
367     u_int out;
368 
369     *stats = state->stats;
370     stats->ratio = stats->unc_bytes;
371     out = stats->comp_bytes + stats->inc_bytes;
372     if (stats->ratio <= 0x7ffffff)
373 	stats->ratio <<= 8;
374     else
375 	out >>= 8;
376     if (out != 0)
377 	stats->ratio /= out;
378 }
379 
380 /*
381  * Allocate space for a decompressor.
382  */
383 static void *
384 z_decomp_alloc(options, opt_len)
385     u_char *options;
386     int opt_len;
387 {
388     struct deflate_state *state;
389     int w_size;
390 
391     if (opt_len != CILEN_DEFLATE
392 	|| (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
393 	|| options[1] != CILEN_DEFLATE
394 	|| DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
395 	|| options[3] != DEFLATE_CHK_SEQUENCE)
396 	return NULL;
397     w_size = DEFLATE_SIZE(options[2]);
398     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
399 	return NULL;
400 
401     MALLOC(state, struct deflate_state *, sizeof(struct deflate_state),
402 	   M_DEVBUF, M_NOWAIT);
403     if (state == NULL)
404 	return NULL;
405 
406     state->strm.next_out = NULL;
407     state->strm.zalloc = zalloc;
408     state->strm.zfree = zfree;
409     if (inflateInit2(&state->strm, -w_size) != Z_OK) {
410 	FREE(state, M_DEVBUF);
411 	return NULL;
412     }
413 
414     state->w_size = w_size;
415     bzero(&state->stats, sizeof(state->stats));
416     return (void *) state;
417 }
418 
419 static void
420 z_decomp_free(arg)
421     void *arg;
422 {
423     struct deflate_state *state = (struct deflate_state *) arg;
424 
425     inflateEnd(&state->strm);
426     FREE(state, M_DEVBUF);
427 }
428 
429 static int
430 z_decomp_init(arg, options, opt_len, unit, hdrlen, mru, debug)
431     void *arg;
432     u_char *options;
433     int opt_len, unit, hdrlen, mru, debug;
434 {
435     struct deflate_state *state = (struct deflate_state *) arg;
436 
437     if (opt_len < CILEN_DEFLATE
438 	|| (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
439 	|| options[1] != CILEN_DEFLATE
440 	|| DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
441 	|| DEFLATE_SIZE(options[2]) != state->w_size
442 	|| options[3] != DEFLATE_CHK_SEQUENCE)
443 	return 0;
444 
445     state->seqno = 0;
446     state->unit = unit;
447     state->hdrlen = hdrlen;
448     state->debug = debug;
449     state->mru = mru;
450 
451     inflateReset(&state->strm);
452 
453     return 1;
454 }
455 
456 static void
457 z_decomp_reset(arg)
458     void *arg;
459 {
460     struct deflate_state *state = (struct deflate_state *) arg;
461 
462     state->seqno = 0;
463     inflateReset(&state->strm);
464 }
465 
466 /*
467  * Decompress a Deflate-compressed packet.
468  *
469  * Because of patent problems, we return DECOMP_ERROR for errors
470  * found by inspecting the input data and for system problems, but
471  * DECOMP_FATALERROR for any errors which could possibly be said to
472  * be being detected "after" decompression.  For DECOMP_ERROR,
473  * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
474  * infringing a patent of Motorola's if we do, so we take CCP down
475  * instead.
476  *
477  * Given that the frame has the correct sequence number and a good FCS,
478  * errors such as invalid codes in the input most likely indicate a
479  * bug, so we return DECOMP_FATALERROR for them in order to turn off
480  * compression, even though they are detected by inspecting the input.
481  */
482 int
483 z_decompress(arg, mi, mop)
484     void *arg;
485     struct mbuf *mi, **mop;
486 {
487     struct deflate_state *state = (struct deflate_state *) arg;
488     struct mbuf *mo, *mo_head;
489     u_char *rptr, *wptr;
490     int rlen, olen, ospace;
491     int seq, i, flush, r, decode_proto;
492     u_char hdr[PPP_HDRLEN + DEFLATE_OVHD];
493 
494     *mop = NULL;
495     rptr = mtod(mi, u_char *);
496     rlen = mi->m_len;
497     for (i = 0; i < PPP_HDRLEN + DEFLATE_OVHD; ++i) {
498 	while (rlen <= 0) {
499 	    mi = mi->m_next;
500 	    if (mi == NULL)
501 		return DECOMP_ERROR;
502 	    rptr = mtod(mi, u_char *);
503 	    rlen = mi->m_len;
504 	}
505 	hdr[i] = *rptr++;
506 	--rlen;
507     }
508 
509     /* Check the sequence number. */
510     seq = (hdr[PPP_HDRLEN] << 8) + hdr[PPP_HDRLEN+1];
511     if (seq != state->seqno) {
512 	if (state->debug)
513 	    printf("z_decompress%d: bad seq # %d, expected %d\n",
514 		   state->unit, seq, state->seqno);
515 	return DECOMP_ERROR;
516     }
517     ++state->seqno;
518 
519     /* Allocate an output mbuf. */
520     MGETHDR(mo, M_DONTWAIT, MT_DATA);
521     if (mo == NULL)
522 	return DECOMP_ERROR;
523     mo_head = mo;
524     mo->m_len = 0;
525     mo->m_next = NULL;
526     MCLGET(mo, M_DONTWAIT);
527     ospace = M_TRAILINGSPACE(mo);
528     if (state->hdrlen + PPP_HDRLEN < ospace) {
529 	mo->m_data += state->hdrlen;
530 	ospace -= state->hdrlen;
531     }
532 
533     /*
534      * Fill in the first part of the PPP header.  The protocol field
535      * comes from the decompressed data.
536      */
537     wptr = mtod(mo, u_char *);
538     wptr[0] = PPP_ADDRESS(hdr);
539     wptr[1] = PPP_CONTROL(hdr);
540     wptr[2] = 0;
541 
542     /*
543      * Set up to call inflate.  We set avail_out to 1 initially so we can
544      * look at the first byte of the output and decide whether we have
545      * a 1-byte or 2-byte protocol field.
546      */
547     state->strm.next_in = rptr;
548     state->strm.avail_in = rlen;
549     mi = mi->m_next;
550     flush = (mi == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
551     rlen += PPP_HDRLEN + DEFLATE_OVHD;
552     state->strm.next_out = wptr + 3;
553     state->strm.avail_out = 1;
554     decode_proto = 1;
555     olen = PPP_HDRLEN;
556 
557     /*
558      * Call inflate, supplying more input or output as needed.
559      */
560     for (;;) {
561 	r = inflate(&state->strm, flush);
562 	if (r != Z_OK) {
563 #ifndef DEFLATE_DEBUG
564 	    if (state->debug)
565 #endif
566 		printf("z_decompress%d: inflate returned %d (%s)\n",
567 		       state->unit, r, (state->strm.msg? state->strm.msg: ""));
568 	    m_freem(mo_head);
569 	    return DECOMP_FATALERROR;
570 	}
571 	if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
572 	    break;		/* all done */
573 	if (state->strm.avail_in == 0 && mi != NULL) {
574 	    state->strm.next_in = mtod(mi, u_char *);
575 	    state->strm.avail_in = mi->m_len;
576 	    rlen += mi->m_len;
577 	    mi = mi->m_next;
578 	    if (mi == NULL)
579 		flush = Z_PACKET_FLUSH;
580 	}
581 	if (state->strm.avail_out == 0) {
582 	    if (decode_proto) {
583 		state->strm.avail_out = ospace - PPP_HDRLEN;
584 		if ((wptr[3] & 1) == 0) {
585 		    /* 2-byte protocol field */
586 		    wptr[2] = wptr[3];
587 		    --state->strm.next_out;
588 		    ++state->strm.avail_out;
589 		    --olen;
590 		}
591 		decode_proto = 0;
592 	    } else {
593 		mo->m_len = ospace;
594 		olen += ospace;
595 		MGET(mo->m_next, M_DONTWAIT, MT_DATA);
596 		mo = mo->m_next;
597 		if (mo == NULL) {
598 		    m_freem(mo_head);
599 		    return DECOMP_ERROR;
600 		}
601 		MCLGET(mo, M_DONTWAIT);
602 		state->strm.next_out = mtod(mo, u_char *);
603 		state->strm.avail_out = ospace = M_TRAILINGSPACE(mo);
604 	    }
605 	}
606     }
607     if (decode_proto) {
608 	m_freem(mo_head);
609 	return DECOMP_ERROR;
610     }
611     olen += (mo->m_len = ospace - state->strm.avail_out);
612 #ifdef DEFLATE_DEBUG
613     if (olen > state->mru + PPP_HDRLEN)
614 	printf("ppp_deflate%d: exceeded mru (%d > %d)\n",
615 	       state->unit, olen, state->mru + PPP_HDRLEN);
616 #endif
617 
618     state->stats.unc_bytes += olen;
619     state->stats.unc_packets++;
620     state->stats.comp_bytes += rlen;
621     state->stats.comp_packets++;
622 
623     *mop = mo_head;
624     return DECOMP_OK;
625 }
626 
627 /*
628  * Incompressible data has arrived - add it to the history.
629  */
630 static void
631 z_incomp(arg, mi)
632     void *arg;
633     struct mbuf *mi;
634 {
635     struct deflate_state *state = (struct deflate_state *) arg;
636     u_char *rptr;
637     int rlen, proto, r;
638 
639     /*
640      * Check that the protocol is one we handle.
641      */
642     rptr = mtod(mi, u_char *);
643     proto = PPP_PROTOCOL(rptr);
644     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
645 	return;
646 
647     ++state->seqno;
648 
649     /*
650      * Iterate through the mbufs, adding the characters in them
651      * to the decompressor's history.  For the first mbuf, we start
652      * at the either the 1st or 2nd byte of the protocol field,
653      * depending on whether the protocol value is compressible.
654      */
655     rlen = mi->m_len;
656     state->strm.next_in = rptr + 3;
657     state->strm.avail_in = rlen - 3;
658     if (proto > 0xff) {
659 	--state->strm.next_in;
660 	++state->strm.avail_in;
661     }
662     for (;;) {
663 	r = inflateIncomp(&state->strm);
664 	if (r != Z_OK) {
665 	    /* gak! */
666 #ifndef DEFLATE_DEBUG
667 	    if (state->debug)
668 #endif
669 		printf("z_incomp%d: inflateIncomp returned %d (%s)\n",
670 		       state->unit, r, (state->strm.msg? state->strm.msg: ""));
671 	    return;
672 	}
673 	mi = mi->m_next;
674 	if (mi == NULL)
675 	    break;
676 	state->strm.next_in = mtod(mi, u_char *);
677 	state->strm.avail_in = mi->m_len;
678 	rlen += mi->m_len;
679     }
680 
681     /*
682      * Update stats.
683      */
684     state->stats.inc_bytes += rlen;
685     state->stats.inc_packets++;
686     state->stats.unc_bytes += rlen;
687     state->stats.unc_packets++;
688 }
689 
690 #endif /* DO_DEFLATE */
691