sys/net/ppp-deflate.c

   1 /*      $NetBSD: ppp-deflate.c,v 1.19 2008/11/29 23:15:20 cube 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@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 1.19 2008/11/29 23:15:20 cube 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, NULL);
 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 */