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ppp-deflate.c revision 1.20.24.1
      1 /*	$NetBSD: ppp-deflate.c,v 1.20.24.1 2017/12/03 11:39:02 jdolecek Exp $	*/
      2 /*	Id: ppp-deflate.c,v 1.5 1997/03/04 03:33:28 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 (at) 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/cdefs.h>
     42 __KERNEL_RCSID(0, "$NetBSD: ppp-deflate.c,v 1.20.24.1 2017/12/03 11:39:02 jdolecek Exp $");
     43 
     44 #include <sys/param.h>
     45 #include <sys/systm.h>
     46 #include <sys/mbuf.h>
     47 #include <sys/module.h>
     48 #include <net/if.h>
     49 #include <net/ppp_defs.h>
     50 #include <net/if_ppp.h>
     51 #include <net/zlib.h>
     52 
     53 #define PACKETPTR	struct mbuf *
     54 #include <net/ppp-comp.h>
     55 
     56 #if DO_DEFLATE
     57 
     58 #define DEFLATE_DEBUG	1
     59 
     60 /*
     61  * State for a Deflate (de)compressor.
     62  */
     63 struct deflate_state {
     64     int		seqno;
     65     int		w_size;
     66     int		unit;
     67     int		hdrlen;
     68     int		mru;
     69     int		debug;
     70     z_stream	strm;
     71     struct compstat stats;
     72 };
     73 
     74 #define DEFLATE_OVHD	2		/* Deflate overhead/packet */
     75 
     76 static void	*zalloc(void *, u_int items, u_int size);
     77 static void	zfree(void *, void *ptr);
     78 static void	*z_comp_alloc(u_char *options, int opt_len);
     79 static void	*z_decomp_alloc(u_char *options, int opt_len);
     80 static void	z_comp_free(void *state);
     81 static void	z_decomp_free(void *state);
     82 static int	z_comp_init(void *state, u_char *options, int opt_len,
     83 			    int unit, int hdrlen, int debug);
     84 static int	z_decomp_init(void *state, u_char *options, int opt_len,
     85 			      int unit, int hdrlen, int mru, int debug);
     86 static int	z_compress(void *state, struct mbuf **mret,
     87 			   struct mbuf *mp, int slen, int maxolen);
     88 static void	z_incomp(void *state, struct mbuf *dmsg);
     89 static int	z_decompress(void *state, struct mbuf *cmp,
     90 			     struct mbuf **dmpp);
     91 static void	z_comp_reset(void *state);
     92 static void	z_decomp_reset(void *state);
     93 static void	z_comp_stats(void *state, struct compstat *stats);
     94 
     95 /*
     96  * Procedures exported to if_ppp.c.
     97  */
     98 static struct compressor ppp_deflate[2] = { {
     99     .compress_proto =	CI_DEFLATE,
    100     .comp_alloc =	z_comp_alloc,
    101     .comp_free =	z_comp_free,
    102     .comp_init =	z_comp_init,
    103     .comp_reset =	z_comp_reset,
    104     .compress =		z_compress,
    105     .comp_stat =	z_comp_stats,
    106     .decomp_alloc =	z_decomp_alloc,
    107     .decomp_free =	z_decomp_free,
    108     .decomp_init =	z_decomp_init,
    109     .decomp_reset =	z_decomp_reset,
    110     .decompress =	z_decompress,
    111     .incomp =		z_incomp,
    112     .decomp_stat =	z_comp_stats,
    113 },
    114 {
    115     .compress_proto =	CI_DEFLATE_DRAFT,
    116     .comp_alloc =	z_comp_alloc,
    117     .comp_free =	z_comp_free,
    118     .comp_init =	z_comp_init,
    119     .comp_reset =	z_comp_reset,
    120     .compress =		z_compress,
    121     .comp_stat =	z_comp_stats,
    122     .decomp_alloc =	z_decomp_alloc,
    123     .decomp_free =	z_decomp_free,
    124     .decomp_init =	z_decomp_init,
    125     .decomp_reset =	z_decomp_reset,
    126     .decompress =	z_decompress,
    127     .incomp =		z_incomp,
    128     .decomp_stat =	z_comp_stats,
    129 } };
    130 /*
    131  * Space allocation and freeing routines for use by zlib routines.
    132  */
    133 void *
    134 zalloc(void *notused, u_int items, u_int size)
    135 {
    136     void *ptr;
    137 
    138     ptr = malloc(items * size, M_DEVBUF, M_NOWAIT);
    139     return ptr;
    140 }
    141 
    142 void
    143 zfree(void *notused, void *ptr)
    144 {
    145     free(ptr, M_DEVBUF);
    146 }
    147 
    148 /*
    149  * Allocate space for a compressor.
    150  */
    151 static void *
    152 z_comp_alloc(u_char *options, int opt_len)
    153 {
    154     struct deflate_state *state;
    155     int w_size;
    156 
    157     if (opt_len != CILEN_DEFLATE
    158 	|| (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
    159 	|| options[1] != CILEN_DEFLATE
    160 	|| DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
    161 	|| options[3] != DEFLATE_CHK_SEQUENCE)
    162 	return NULL;
    163     w_size = DEFLATE_SIZE(options[2]);
    164     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
    165 	return NULL;
    166 
    167     state = malloc(sizeof(struct deflate_state), M_DEVBUF, M_NOWAIT);
    168     if (state == NULL)
    169 	return NULL;
    170 
    171     state->strm.next_in = NULL;
    172     state->strm.zalloc = zalloc;
    173     state->strm.zfree = zfree;
    174     if (deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION, DEFLATE_METHOD_VAL,
    175 		     -w_size, 8, Z_DEFAULT_STRATEGY) != Z_OK) {
    176 	free(state, M_DEVBUF);
    177 	return NULL;
    178     }
    179 
    180     state->w_size = w_size;
    181     memset(&state->stats, 0, sizeof(state->stats));
    182     return (void *) state;
    183 }
    184 
    185 static void
    186 z_comp_free(void *arg)
    187 {
    188     struct deflate_state *state = (struct deflate_state *) arg;
    189 
    190     deflateEnd(&state->strm);
    191     free(state, M_DEVBUF);
    192 }
    193 
    194 static int
    195 z_comp_init(void *arg, u_char *options, int opt_len, int unit, int hdrlen,
    196             int debug)
    197 {
    198     struct deflate_state *state = (struct deflate_state *) arg;
    199 
    200     if (opt_len < CILEN_DEFLATE
    201 	|| (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
    202 	|| options[1] != CILEN_DEFLATE
    203 	|| DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
    204 	|| DEFLATE_SIZE(options[2]) != state->w_size
    205 	|| options[3] != DEFLATE_CHK_SEQUENCE)
    206 	return 0;
    207 
    208     state->seqno = 0;
    209     state->unit = unit;
    210     state->hdrlen = hdrlen;
    211     state->debug = debug;
    212 
    213     deflateReset(&state->strm);
    214 
    215     return 1;
    216 }
    217 
    218 static void
    219 z_comp_reset(void *arg)
    220 {
    221     struct deflate_state *state = (struct deflate_state *) arg;
    222 
    223     state->seqno = 0;
    224     deflateReset(&state->strm);
    225 }
    226 
    227 int
    228 z_compress(void *arg,
    229            struct mbuf **mret /* compressed packet (out) */,
    230 	   struct mbuf *mp /* uncompressed packet (in) */,
    231 	   int orig_len, int maxolen)
    232 {
    233     struct deflate_state *state = (struct deflate_state *) arg;
    234     u_char *rptr, *wptr;
    235     int proto, olen, wspace, r, flush;
    236     struct mbuf *m;
    237 
    238     /*
    239      * Check that the protocol is in the range we handle.
    240      */
    241     rptr = mtod(mp, u_char *);
    242     proto = PPP_PROTOCOL(rptr);
    243     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb) {
    244 	*mret = NULL;
    245 	return orig_len;
    246     }
    247 
    248     /* Allocate one mbuf initially. */
    249     if (maxolen > orig_len)
    250 	maxolen = orig_len;
    251     MGET(m, M_DONTWAIT, MT_DATA);
    252     *mret = m;
    253     if (m != NULL) {
    254 	m->m_len = 0;
    255 	if (maxolen + state->hdrlen > MLEN)
    256 	    MCLGET(m, M_DONTWAIT);
    257 	wspace = M_TRAILINGSPACE(m);
    258 	if (state->hdrlen + PPP_HDRLEN + 2 < wspace) {
    259 	    m->m_data += state->hdrlen;
    260 	    wspace -= state->hdrlen;
    261 	}
    262 	wptr = mtod(m, u_char *);
    263 
    264 	/*
    265 	 * Copy over the PPP header and store the 2-byte sequence number.
    266 	 */
    267 	wptr[0] = PPP_ADDRESS(rptr);
    268 	wptr[1] = PPP_CONTROL(rptr);
    269 	wptr[2] = PPP_COMP >> 8;
    270 	wptr[3] = PPP_COMP;
    271 	wptr += PPP_HDRLEN;
    272 	wptr[0] = state->seqno >> 8;
    273 	wptr[1] = state->seqno;
    274 	wptr += 2;
    275 	state->strm.next_out = wptr;
    276 	state->strm.avail_out = wspace - (PPP_HDRLEN + 2);
    277     } else {
    278 	state->strm.next_out = NULL;
    279 	state->strm.avail_out = 1000000;
    280 	wptr = NULL;
    281 	wspace = 0;
    282     }
    283     ++state->seqno;
    284 
    285     rptr += (proto > 0xff)? 2: 3;	/* skip 1st proto byte if 0 */
    286     state->strm.next_in = rptr;
    287     state->strm.avail_in = mtod(mp, u_char *) + mp->m_len - rptr;
    288     mp = mp->m_next;
    289     flush = (mp == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
    290     olen = 0;
    291     for (;;) {
    292 	r = deflate(&state->strm, flush);
    293 	if (r != Z_OK) {
    294 	    printf("z_compress: deflate returned %d (%s)\n",
    295 		   r, (state->strm.msg? state->strm.msg: ""));
    296 	    break;
    297 	}
    298 	if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
    299 	    break;		/* all done */
    300 	if (state->strm.avail_in == 0 && mp != NULL) {
    301 	    state->strm.next_in = mtod(mp, u_char *);
    302 	    state->strm.avail_in = mp->m_len;
    303 	    mp = mp->m_next;
    304 	    if (mp == NULL)
    305 		flush = Z_PACKET_FLUSH;
    306 	}
    307 	if (state->strm.avail_out == 0) {
    308 	    if (m != NULL) {
    309 		m->m_len = wspace;
    310 		olen += wspace;
    311 		MGET(m->m_next, M_DONTWAIT, MT_DATA);
    312 		m = m->m_next;
    313 		if (m != NULL) {
    314 		    m->m_len = 0;
    315 		    if (maxolen - olen > MLEN)
    316 			MCLGET(m, M_DONTWAIT);
    317 		    state->strm.next_out = mtod(m, u_char *);
    318 		    state->strm.avail_out = wspace = M_TRAILINGSPACE(m);
    319 		}
    320 	    }
    321 	    if (m == NULL) {
    322 		state->strm.next_out = NULL;
    323 		state->strm.avail_out = 1000000;
    324 	    }
    325 	}
    326     }
    327     if (m != NULL)
    328 	olen += (m->m_len = wspace - state->strm.avail_out);
    329 
    330     /*
    331      * See if we managed to reduce the size of the packet.
    332      */
    333     if (m != NULL && olen < orig_len) {
    334 	state->stats.comp_bytes += olen;
    335 	state->stats.comp_packets++;
    336     } else {
    337 	if (*mret != NULL) {
    338 	    m_freem(*mret);
    339 	    *mret = NULL;
    340 	}
    341 	state->stats.inc_bytes += orig_len;
    342 	state->stats.inc_packets++;
    343 	olen = orig_len;
    344     }
    345     state->stats.unc_bytes += orig_len;
    346     state->stats.unc_packets++;
    347 
    348     return olen;
    349 }
    350 
    351 static void
    352 z_comp_stats(void *arg, struct compstat *stats)
    353 {
    354     struct deflate_state *state = (struct deflate_state *) arg;
    355     u_int out;
    356 
    357     *stats = state->stats;
    358     stats->ratio = stats->unc_bytes;
    359     out = stats->comp_bytes + stats->inc_bytes;
    360     if (stats->ratio <= 0x7ffffff)
    361 	stats->ratio <<= 8;
    362     else
    363 	out >>= 8;
    364     if (out != 0)
    365 	stats->ratio /= out;
    366 }
    367 
    368 /*
    369  * Allocate space for a decompressor.
    370  */
    371 static void *
    372 z_decomp_alloc(u_char *options, int opt_len)
    373 {
    374     struct deflate_state *state;
    375     int w_size;
    376 
    377     if (opt_len != CILEN_DEFLATE
    378 	|| (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
    379 	|| options[1] != CILEN_DEFLATE
    380 	|| DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
    381 	|| options[3] != DEFLATE_CHK_SEQUENCE)
    382 	return NULL;
    383     w_size = DEFLATE_SIZE(options[2]);
    384     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
    385 	return NULL;
    386 
    387     state = malloc(sizeof(struct deflate_state), M_DEVBUF, M_NOWAIT);
    388     if (state == NULL)
    389 	return NULL;
    390 
    391     state->strm.next_out = NULL;
    392     state->strm.zalloc = zalloc;
    393     state->strm.zfree = zfree;
    394     if (inflateInit2(&state->strm, -w_size) != Z_OK) {
    395 	free(state, M_DEVBUF);
    396 	return NULL;
    397     }
    398 
    399     state->w_size = w_size;
    400     memset(&state->stats, 0, sizeof(state->stats));
    401     return (void *) state;
    402 }
    403 
    404 static void
    405 z_decomp_free(void *arg)
    406 {
    407     struct deflate_state *state = (struct deflate_state *) arg;
    408 
    409     inflateEnd(&state->strm);
    410     free(state, M_DEVBUF);
    411 }
    412 
    413 static int
    414 z_decomp_init(void *arg, u_char *options, int opt_len, int unit, int hdrlen,
    415               int mru, int debug)
    416 {
    417     struct deflate_state *state = (struct deflate_state *) arg;
    418 
    419     if (opt_len < CILEN_DEFLATE
    420 	|| (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
    421 	|| options[1] != CILEN_DEFLATE
    422 	|| DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
    423 	|| DEFLATE_SIZE(options[2]) != state->w_size
    424 	|| options[3] != DEFLATE_CHK_SEQUENCE)
    425 	return 0;
    426 
    427     state->seqno = 0;
    428     state->unit = unit;
    429     state->hdrlen = hdrlen;
    430     state->debug = debug;
    431     state->mru = mru;
    432 
    433     inflateReset(&state->strm);
    434 
    435     return 1;
    436 }
    437 
    438 static void
    439 z_decomp_reset(void *arg)
    440 {
    441     struct deflate_state *state = (struct deflate_state *) arg;
    442 
    443     state->seqno = 0;
    444     inflateReset(&state->strm);
    445 }
    446 
    447 /*
    448  * Decompress a Deflate-compressed packet.
    449  *
    450  * Because of patent problems, we return DECOMP_ERROR for errors
    451  * found by inspecting the input data and for system problems, but
    452  * DECOMP_FATALERROR for any errors which could possibly be said to
    453  * be being detected "after" decompression.  For DECOMP_ERROR,
    454  * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
    455  * infringing a patent of Motorola's if we do, so we take CCP down
    456  * instead.
    457  *
    458  * Given that the frame has the correct sequence number and a good FCS,
    459  * errors such as invalid codes in the input most likely indicate a
    460  * bug, so we return DECOMP_FATALERROR for them in order to turn off
    461  * compression, even though they are detected by inspecting the input.
    462  */
    463 int
    464 z_decompress(void *arg, struct mbuf *mi, struct mbuf **mop)
    465 {
    466     struct deflate_state *state = (struct deflate_state *) arg;
    467     struct mbuf *mo, *mo_head;
    468     u_char *rptr, *wptr;
    469     int rlen, olen, ospace;
    470     int seq, i, flush, r, decode_proto;
    471     u_char hdr[PPP_HDRLEN + DEFLATE_OVHD];
    472 
    473     *mop = NULL;
    474     rptr = mtod(mi, u_char *);
    475     rlen = mi->m_len;
    476     for (i = 0; i < PPP_HDRLEN + DEFLATE_OVHD; ++i) {
    477 	while (rlen <= 0) {
    478 	    mi = mi->m_next;
    479 	    if (mi == NULL)
    480 		return DECOMP_ERROR;
    481 	    rptr = mtod(mi, u_char *);
    482 	    rlen = mi->m_len;
    483 	}
    484 	hdr[i] = *rptr++;
    485 	--rlen;
    486     }
    487 
    488     /* Check the sequence number. */
    489     seq = (hdr[PPP_HDRLEN] << 8) + hdr[PPP_HDRLEN+1];
    490     if (seq != state->seqno) {
    491 	if (state->debug)
    492 	    printf("z_decompress%d: bad seq # %d, expected %d\n",
    493 		   state->unit, seq, state->seqno);
    494 	return DECOMP_ERROR;
    495     }
    496     ++state->seqno;
    497 
    498     /* Allocate an output mbuf. */
    499     MGETHDR(mo, M_DONTWAIT, MT_DATA);
    500     if (mo == NULL)
    501 	return DECOMP_ERROR;
    502     mo_head = mo;
    503     mo->m_len = 0;
    504     mo->m_next = NULL;
    505     MCLGET(mo, M_DONTWAIT);
    506     ospace = M_TRAILINGSPACE(mo);
    507     if (state->hdrlen + PPP_HDRLEN < ospace) {
    508 	mo->m_data += state->hdrlen;
    509 	ospace -= state->hdrlen;
    510     }
    511 
    512     /*
    513      * Fill in the first part of the PPP header.  The protocol field
    514      * comes from the decompressed data.
    515      */
    516     wptr = mtod(mo, u_char *);
    517     wptr[0] = PPP_ADDRESS(hdr);
    518     wptr[1] = PPP_CONTROL(hdr);
    519     wptr[2] = 0;
    520 
    521     /*
    522      * Set up to call inflate.  We set avail_out to 1 initially so we can
    523      * look at the first byte of the output and decide whether we have
    524      * a 1-byte or 2-byte protocol field.
    525      */
    526     state->strm.next_in = rptr;
    527     state->strm.avail_in = rlen;
    528     mi = mi->m_next;
    529     flush = (mi == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
    530     rlen += PPP_HDRLEN + DEFLATE_OVHD;
    531     state->strm.next_out = wptr + 3;
    532     state->strm.avail_out = 1;
    533     decode_proto = 1;
    534     olen = 0;
    535 
    536     /*
    537      * Call inflate, supplying more input or output as needed.
    538      */
    539     for (;;) {
    540 	r = inflate(&state->strm, flush);
    541 	if (r != Z_OK) {
    542 #if !DEFLATE_DEBUG
    543 	    if (state->debug)
    544 #endif
    545 		printf("z_decompress%d: inflate returned %d (%s)\n",
    546 		       state->unit, r, (state->strm.msg? state->strm.msg: ""));
    547 	    m_freem(mo_head);
    548 	    return DECOMP_FATALERROR;
    549 	}
    550 	if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
    551 	    break;		/* all done */
    552 	if (state->strm.avail_in == 0 && mi != NULL) {
    553 	    state->strm.next_in = mtod(mi, u_char *);
    554 	    state->strm.avail_in = mi->m_len;
    555 	    rlen += mi->m_len;
    556 	    mi = mi->m_next;
    557 	    if (mi == NULL)
    558 		flush = Z_PACKET_FLUSH;
    559 	}
    560 	if (state->strm.avail_out == 0) {
    561 	    if (decode_proto) {
    562 		state->strm.avail_out = ospace - PPP_HDRLEN;
    563 		if ((wptr[3] & 1) == 0) {
    564 		    /* 2-byte protocol field */
    565 		    wptr[2] = wptr[3];
    566 		    --state->strm.next_out;
    567 		    ++state->strm.avail_out;
    568 		    --olen;
    569 		}
    570 		decode_proto = 0;
    571 	    } else {
    572 		mo->m_len = ospace;
    573 		olen += ospace;
    574 		MGET(mo->m_next, M_DONTWAIT, MT_DATA);
    575 		mo = mo->m_next;
    576 		if (mo == NULL) {
    577 		    m_freem(mo_head);
    578 		    return DECOMP_ERROR;
    579 		}
    580 		MCLGET(mo, M_DONTWAIT);
    581 		state->strm.next_out = mtod(mo, u_char *);
    582 		state->strm.avail_out = ospace = M_TRAILINGSPACE(mo);
    583 	    }
    584 	}
    585     }
    586     if (decode_proto) {
    587 	m_freem(mo_head);
    588 	return DECOMP_ERROR;
    589     }
    590     olen += (mo->m_len = ospace - state->strm.avail_out);
    591 #if DEFLATE_DEBUG
    592     if (olen > state->mru + PPP_HDRLEN)
    593 	printf("ppp_deflate%d: exceeded mru (%d > %d)\n",
    594 	       state->unit, olen, state->mru + PPP_HDRLEN);
    595 #endif
    596 
    597     state->stats.unc_bytes += olen;
    598     state->stats.unc_packets++;
    599     state->stats.comp_bytes += rlen;
    600     state->stats.comp_packets++;
    601 
    602     *mop = mo_head;
    603     return DECOMP_OK;
    604 }
    605 
    606 /*
    607  * Incompressible data has arrived - add it to the history.
    608  */
    609 static void
    610 z_incomp(void *arg, struct mbuf *mi)
    611 {
    612     struct deflate_state *state = (struct deflate_state *) arg;
    613     u_char *rptr;
    614     int rlen, proto, r;
    615 
    616     /*
    617      * Check that the protocol is one we handle.
    618      */
    619     rptr = mtod(mi, u_char *);
    620     proto = PPP_PROTOCOL(rptr);
    621     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
    622 	return;
    623 
    624     ++state->seqno;
    625 
    626     /*
    627      * Iterate through the mbufs, adding the characters in them
    628      * to the decompressor's history.  For the first mbuf, we start
    629      * at the either the 1st or 2nd byte of the protocol field,
    630      * depending on whether the protocol value is compressible.
    631      */
    632     rlen = mi->m_len;
    633     state->strm.next_in = rptr + 3;
    634     state->strm.avail_in = rlen - 3;
    635     if (proto > 0xff) {
    636 	--state->strm.next_in;
    637 	++state->strm.avail_in;
    638     }
    639     for (;;) {
    640 	r = inflateIncomp(&state->strm);
    641 	if (r != Z_OK) {
    642 	    /* gak! */
    643 #if !DEFLATE_DEBUG
    644 	    if (state->debug)
    645 #endif
    646 		printf("z_incomp%d: inflateIncomp returned %d (%s)\n",
    647 		       state->unit, r, (state->strm.msg? state->strm.msg: ""));
    648 	    return;
    649 	}
    650 	mi = mi->m_next;
    651 	if (mi == NULL)
    652 	    break;
    653 	state->strm.next_in = mtod(mi, u_char *);
    654 	state->strm.avail_in = mi->m_len;
    655 	rlen += mi->m_len;
    656     }
    657 
    658     /*
    659      * Update stats.
    660      */
    661     state->stats.inc_bytes += rlen;
    662     state->stats.inc_packets++;
    663     state->stats.unc_bytes += rlen;
    664     state->stats.unc_packets++;
    665 }
    666 
    667 MODULE(MODULE_CLASS_MISC, ppp_deflate, "zlib,if_ppp");
    668 
    669 static int
    670 ppp_deflate_modcmd(modcmd_t cmd, void *arg)
    671 {
    672 
    673 	switch (cmd) {
    674 	case MODULE_CMD_INIT:
    675 		return ppp_register_compressor(ppp_deflate, 2);
    676 	case MODULE_CMD_FINI:
    677 		return ppp_unregister_compressor(ppp_deflate, 2);
    678 	case MODULE_CMD_STAT:
    679 		return 0;
    680 	default:
    681 		return ENOTTY;
    682 	}
    683 
    684 	return ENOTTY;
    685 }
    686 #endif /* DO_DEFLATE */
    687