sys/net/ppp_layer/ppp_deflate.c

   1 /* $FreeBSD: src/sys/net/ppp_deflate.c,v 1.12.2.1 2002/04/14 21:41:48 luigi Exp $       */
   2
   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 mbufs on BSD-derived systems.
   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
  32 #include <sys/param.h>
  33 #include <sys/systm.h>
  34 #include <sys/malloc.h>
  35 #include <sys/mbuf.h>
  36 #include "ppp_defs.h"
  37 #include <net/zlib.h>
  38
  39 #define PACKETPTR       struct mbuf *
  40 #include "ppp_comp.h"
  41
  42 #if DO_DEFLATE
  43
  44 #define DEFLATE_DEBUG   1
  45
  46 /*
  47  * State for a Deflate (de)compressor.
  48  */
  49 struct deflate_state {
  50     int         seqno;
  51     int         w_size;
  52     int         unit;
  53     int         hdrlen;
  54     int         mru;
  55     int         debug;
  56     z_stream    strm;
  57     struct compstat stats;
  58 };
  59
  60 #define DEFLATE_OVHD    2               /* Deflate overhead/packet */
  61
  62 static void     *z_alloc (void *, u_int items, u_int size);
  63 static void     z_free (void *, void *ptr);
  64 static void     *z_comp_alloc (u_char *options, int opt_len);
  65 static void     *z_decomp_alloc (u_char *options, int opt_len);
  66 static void     z_comp_free (void *state);
  67 static void     z_decomp_free (void *state);
  68 static int      z_comp_init (void *state, u_char *options, int opt_len,
  69                                  int unit, int hdrlen, int debug);
  70 static int      z_decomp_init (void *state, u_char *options, int opt_len,
  71                                      int unit, int hdrlen, int mru, int debug);
  72 static int      z_compress (void *state, struct mbuf **mret,
  73                                   struct mbuf *mp, int slen, int maxolen);
  74 static void     z_incomp (void *state, struct mbuf *dmsg);
  75 static int      z_decompress (void *state, struct mbuf *cmp,
  76                                     struct mbuf **dmpp);
  77 static void     z_comp_reset (void *state);
  78 static void     z_decomp_reset (void *state);
  79 static void     z_comp_stats (void *state, struct compstat *stats);
  80
  81 /*
  82  * Procedures exported to if_ppp.c.
  83  */
  84 struct compressor ppp_deflate = {
  85     CI_DEFLATE,                 /* compress_proto */
  86     z_comp_alloc,               /* comp_alloc */
  87     z_comp_free,                /* comp_free */
  88     z_comp_init,                /* comp_init */
  89     z_comp_reset,               /* comp_reset */
  90     z_compress,                 /* compress */
  91     z_comp_stats,               /* comp_stat */
  92     z_decomp_alloc,             /* decomp_alloc */
  93     z_decomp_free,              /* decomp_free */
  94     z_decomp_init,              /* decomp_init */
  95     z_decomp_reset,             /* decomp_reset */
  96     z_decompress,               /* decompress */
  97     z_incomp,                   /* incomp */
  98     z_comp_stats,               /* decomp_stat */
  99 };
 100
 101 struct compressor ppp_deflate_draft = {
 102     CI_DEFLATE_DRAFT,           /* compress_proto */
 103     z_comp_alloc,               /* comp_alloc */
 104     z_comp_free,                /* comp_free */
 105     z_comp_init,                /* comp_init */
 106     z_comp_reset,               /* comp_reset */
 107     z_compress,                 /* compress */
 108     z_comp_stats,               /* comp_stat */
 109     z_decomp_alloc,             /* decomp_alloc */
 110     z_decomp_free,              /* decomp_free */
 111     z_decomp_init,              /* decomp_init */
 112     z_decomp_reset,             /* decomp_reset */
 113     z_decompress,               /* decompress */
 114     z_incomp,                   /* incomp */
 115     z_comp_stats,               /* decomp_stat */
 116 };
 117
 118 /*
 119  * Space allocation and freeing routines for use by zlib routines.
 120  */
 121 static void *
 122 z_alloc(void *notused, u_int items, u_int size)
 123 {
 124     void *ptr;
 125
 126     ptr = kmalloc(items * size, M_DEVBUF, M_WAITOK);
 127     return ptr;
 128 }
 129
 130 static void
 131 z_free(void *notused, void *ptr)
 132 {
 133     kfree(ptr, M_DEVBUF);
 134 }
 135
 136 /*
 137  * Allocate space for a compressor.
 138  */
 139 static void *
 140 z_comp_alloc(u_char *options, int opt_len)
 141 {
 142     struct deflate_state *state;
 143     int w_size;
 144
 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         || options[3] != DEFLATE_CHK_SEQUENCE)
 150         return NULL;
 151     w_size = DEFLATE_SIZE(options[2]);
 152     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
 153         return NULL;
 154
 155     state = kmalloc(sizeof(struct deflate_state), M_DEVBUF, M_WAITOK);
 156
 157     state->strm.next_in = NULL;
 158     state->strm.zalloc = z_alloc;
 159     state->strm.zfree = z_free;
 160     if (deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION, DEFLATE_METHOD_VAL,
 161                      -w_size, 8, Z_DEFAULT_STRATEGY) != Z_OK) {
 162         kfree(state, M_DEVBUF);
 163         return NULL;
 164     }
 165
 166     state->w_size = w_size;
 167     bzero(&state->stats, sizeof(state->stats));
 168     return (void *) state;
 169 }
 170
 171 static void
 172 z_comp_free(void *arg)
 173 {
 174     struct deflate_state *state = (struct deflate_state *) arg;
 175
 176     deflateEnd(&state->strm);
 177     kfree(state, M_DEVBUF);
 178 }
 179
 180 static int
 181 z_comp_init(void *arg, u_char *options, int opt_len, int unit, int hdrlen,
 182             int debug)
 183 {
 184     struct deflate_state *state = (struct deflate_state *) arg;
 185
 186     if (opt_len < CILEN_DEFLATE
 187         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 188         || options[1] != CILEN_DEFLATE
 189         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 190         || DEFLATE_SIZE(options[2]) != state->w_size
 191         || options[3] != DEFLATE_CHK_SEQUENCE)
 192         return 0;
 193
 194     state->seqno = 0;
 195     state->unit = unit;
 196     state->hdrlen = hdrlen;
 197     state->debug = debug;
 198
 199     deflateReset(&state->strm);
 200
 201     return 1;
 202 }
 203
 204 static void
 205 z_comp_reset(void *arg)
 206 {
 207     struct deflate_state *state = (struct deflate_state *) arg;
 208
 209     state->seqno = 0;
 210     deflateReset(&state->strm);
 211 }
 212
 213 /*
 214  * Parameters:
 215  *      mret:   compressed packet (out)
 216  *      mp:     uncompressed packet (in)
 217  */
 218 static int
 219 z_compress(void *arg, struct mbuf **mret, struct mbuf *mp, int orig_len,
 220            int maxolen)
 221 {
 222     struct deflate_state *state = (struct deflate_state *) arg;
 223     u_char *rptr, *wptr;
 224     int proto, olen, wspace, r, flush;
 225     struct mbuf *m;
 226
 227     /*
 228      * Check that the protocol is in the range we handle.
 229      */
 230     rptr = mtod(mp, u_char *);
 231     proto = PPP_PROTOCOL(rptr);
 232     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb) {
 233         *mret = NULL;
 234         return orig_len;
 235     }
 236
 237     /* Allocate one mbuf initially. */
 238     if (maxolen > orig_len)
 239         maxolen = orig_len;
 240     MGET(m, M_NOWAIT, MT_DATA);
 241     *mret = m;
 242     if (m != NULL) {
 243         m->m_len = 0;
 244         if (maxolen + state->hdrlen > MLEN)
 245             MCLGET(m, M_NOWAIT);
 246         wspace = M_TRAILINGSPACE(m);
 247         if (state->hdrlen + PPP_HDRLEN + 2 < wspace) {
 248             m->m_data += state->hdrlen;
 249             wspace -= state->hdrlen;
 250         }
 251         wptr = mtod(m, u_char *);
 252
 253         /*
 254          * Copy over the PPP header and store the 2-byte sequence number.
 255          */
 256         wptr[0] = PPP_ADDRESS(rptr);
 257         wptr[1] = PPP_CONTROL(rptr);
 258         wptr[2] = PPP_COMP >> 8;
 259         wptr[3] = PPP_COMP;
 260         wptr += PPP_HDRLEN;
 261         wptr[0] = state->seqno >> 8;
 262         wptr[1] = state->seqno;
 263         wptr += 2;
 264         state->strm.next_out = wptr;
 265         state->strm.avail_out = wspace - (PPP_HDRLEN + 2);
 266     } else {
 267         state->strm.next_out = NULL;
 268         state->strm.avail_out = 1000000;
 269         wptr = NULL;
 270         wspace = 0;
 271     }
 272     ++state->seqno;
 273
 274     rptr += (proto > 0xff)? 2: 3;       /* skip 1st proto byte if 0 */
 275     state->strm.next_in = rptr;
 276     state->strm.avail_in = mtod(mp, u_char *) + mp->m_len - rptr;
 277     mp = mp->m_next;
 278     flush = (mp == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 279     olen = 0;
 280     for (;;) {
 281         r = deflate(&state->strm, flush);
 282         if (r != Z_OK) {
 283             kprintf("z_compress: deflate returned %d (%s)\n",
 284                    r, (state->strm.msg? state->strm.msg: ""));
 285             break;
 286         }
 287         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 288             break;              /* all done */
 289         if (state->strm.avail_in == 0 && mp != NULL) {
 290             state->strm.next_in = mtod(mp, u_char *);
 291             state->strm.avail_in = mp->m_len;
 292             mp = mp->m_next;
 293             if (mp == NULL)
 294                 flush = Z_PACKET_FLUSH;
 295         }
 296         if (state->strm.avail_out == 0) {
 297             if (m != NULL) {
 298                 m->m_len = wspace;
 299                 olen += wspace;
 300                 MGET(m->m_next, M_NOWAIT, MT_DATA);
 301                 m = m->m_next;
 302                 if (m != NULL) {
 303                     m->m_len = 0;
 304                     if (maxolen - olen > MLEN)
 305                         MCLGET(m, M_NOWAIT);
 306                     state->strm.next_out = mtod(m, u_char *);
 307                     state->strm.avail_out = wspace = M_TRAILINGSPACE(m);
 308                 }
 309             }
 310             if (m == NULL) {
 311                 state->strm.next_out = NULL;
 312                 state->strm.avail_out = 1000000;
 313             }
 314         }
 315     }
 316     if (m != NULL)
 317         olen += (m->m_len = wspace - state->strm.avail_out);
 318
 319     /*
 320      * See if we managed to reduce the size of the packet.
 321      */
 322     if (m != NULL && olen < orig_len) {
 323         state->stats.comp_bytes += olen;
 324         state->stats.comp_packets++;
 325     } else {
 326         if (*mret != NULL) {
 327             m_freem(*mret);
 328             *mret = NULL;
 329         }
 330         state->stats.inc_bytes += orig_len;
 331         state->stats.inc_packets++;
 332         olen = orig_len;
 333     }
 334     state->stats.unc_bytes += orig_len;
 335     state->stats.unc_packets++;
 336
 337     return olen;
 338 }
 339
 340 static void
 341 z_comp_stats(void *arg, struct compstat *stats)
 342 {
 343     struct deflate_state *state = (struct deflate_state *) arg;
 344     u_int out;
 345
 346     *stats = state->stats;
 347     stats->ratio = stats->unc_bytes;
 348     out = stats->comp_bytes + stats->inc_bytes;
 349     if (stats->ratio <= 0x7ffffff)
 350         stats->ratio <<= 8;
 351     else
 352         out >>= 8;
 353     if (out != 0)
 354         stats->ratio /= out;
 355 }
 356
 357 /*
 358  * Allocate space for a decompressor.
 359  */
 360 static void *
 361 z_decomp_alloc(u_char *options, int opt_len)
 362 {
 363     struct deflate_state *state;
 364     int w_size;
 365
 366     if (opt_len != CILEN_DEFLATE
 367         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 368         || options[1] != CILEN_DEFLATE
 369         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 370         || options[3] != DEFLATE_CHK_SEQUENCE)
 371         return NULL;
 372     w_size = DEFLATE_SIZE(options[2]);
 373     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
 374         return NULL;
 375
 376     state = kmalloc(sizeof(struct deflate_state), M_DEVBUF, M_WAITOK);
 377
 378     state->strm.next_out = NULL;
 379     state->strm.zalloc = z_alloc;
 380     state->strm.zfree = z_free;
 381     if (inflateInit2(&state->strm, -w_size) != Z_OK) {
 382         kfree(state, M_DEVBUF);
 383         return NULL;
 384     }
 385
 386     state->w_size = w_size;
 387     bzero(&state->stats, sizeof(state->stats));
 388     return (void *) state;
 389 }
 390
 391 static void
 392 z_decomp_free(void *arg)
 393 {
 394     struct deflate_state *state = (struct deflate_state *) arg;
 395
 396     inflateEnd(&state->strm);
 397     kfree(state, M_DEVBUF);
 398 }
 399
 400 static int
 401 z_decomp_init(void *arg, u_char *options, int opt_len, int unit, int hdrlen,
 402               int mru, int debug)
 403 {
 404     struct deflate_state *state = (struct deflate_state *) arg;
 405
 406     if (opt_len < CILEN_DEFLATE
 407         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 408         || options[1] != CILEN_DEFLATE
 409         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 410         || DEFLATE_SIZE(options[2]) != state->w_size
 411         || options[3] != DEFLATE_CHK_SEQUENCE)
 412         return 0;
 413
 414     state->seqno = 0;
 415     state->unit = unit;
 416     state->hdrlen = hdrlen;
 417     state->debug = debug;
 418     state->mru = mru;
 419
 420     inflateReset(&state->strm);
 421
 422     return 1;
 423 }
 424
 425 static void
 426 z_decomp_reset(void *arg)
 427 {
 428     struct deflate_state *state = (struct deflate_state *) arg;
 429
 430     state->seqno = 0;
 431     inflateReset(&state->strm);
 432 }
 433
 434 /*
 435  * Decompress a Deflate-compressed packet.
 436  *
 437  * Because of patent problems, we return DECOMP_ERROR for errors
 438  * found by inspecting the input data and for system problems, but
 439  * DECOMP_FATALERROR for any errors which could possibly be said to
 440  * be being detected "after" decompression.  For DECOMP_ERROR,
 441  * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
 442  * infringing a patent of Motorola's if we do, so we take CCP down
 443  * instead.
 444  *
 445  * Given that the frame has the correct sequence number and a good FCS,
 446  * errors such as invalid codes in the input most likely indicate a
 447  * bug, so we return DECOMP_FATALERROR for them in order to turn off
 448  * compression, even though they are detected by inspecting the input.
 449  */
 450 static int
 451 z_decompress(void *arg, struct mbuf *mi, struct mbuf **mop)
 452 {
 453     struct deflate_state *state = (struct deflate_state *) arg;
 454     struct mbuf *mo, *mo_head;
 455     u_char *rptr, *wptr;
 456     int rlen, olen, ospace;
 457     int seq, i, flush, r, decode_proto;
 458     u_char hdr[PPP_HDRLEN + DEFLATE_OVHD];
 459
 460     *mop = NULL;
 461     rptr = mtod(mi, u_char *);
 462     rlen = mi->m_len;
 463     for (i = 0; i < PPP_HDRLEN + DEFLATE_OVHD; ++i) {
 464         while (rlen <= 0) {
 465             mi = mi->m_next;
 466             if (mi == NULL)
 467                 return DECOMP_ERROR;
 468             rptr = mtod(mi, u_char *);
 469             rlen = mi->m_len;
 470         }
 471         hdr[i] = *rptr++;
 472         --rlen;
 473     }
 474
 475     /* Check the sequence number. */
 476     seq = (hdr[PPP_HDRLEN] << 8) + hdr[PPP_HDRLEN+1];
 477     if (seq != state->seqno) {
 478         if (state->debug)
 479             kprintf("z_decompress%d: bad seq # %d, expected %d\n",
 480                    state->unit, seq, state->seqno);
 481         return DECOMP_ERROR;
 482     }
 483     ++state->seqno;
 484
 485     /* Allocate an output mbuf. */
 486     MGETHDR(mo, M_NOWAIT, MT_DATA);
 487     if (mo == NULL)
 488         return DECOMP_ERROR;
 489     mo_head = mo;
 490     mo->m_len = 0;
 491     mo->m_next = NULL;
 492     MCLGET(mo, M_NOWAIT);
 493     ospace = M_TRAILINGSPACE(mo);
 494     if (state->hdrlen + PPP_HDRLEN < ospace) {
 495         mo->m_data += state->hdrlen;
 496         ospace -= state->hdrlen;
 497     }
 498
 499     /*
 500      * Fill in the first part of the PPP header.  The protocol field
 501      * comes from the decompressed data.
 502      */
 503     wptr = mtod(mo, u_char *);
 504     wptr[0] = PPP_ADDRESS(hdr);
 505     wptr[1] = PPP_CONTROL(hdr);
 506     wptr[2] = 0;
 507
 508     /*
 509      * Set up to call inflate.  We set avail_out to 1 initially so we can
 510      * look at the first byte of the output and decide whether we have
 511      * a 1-byte or 2-byte protocol field.
 512      */
 513     state->strm.next_in = rptr;
 514     state->strm.avail_in = rlen;
 515     mi = mi->m_next;
 516     flush = (mi == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 517     rlen += PPP_HDRLEN + DEFLATE_OVHD;
 518     state->strm.next_out = wptr + 3;
 519     state->strm.avail_out = 1;
 520     decode_proto = 1;
 521     olen = PPP_HDRLEN;
 522
 523     /*
 524      * Call inflate, supplying more input or output as needed.
 525      */
 526     for (;;) {
 527         r = inflate(&state->strm, flush);
 528         if (r != Z_OK) {
 529 #if !DEFLATE_DEBUG
 530             if (state->debug)
 531 #endif
 532                 kprintf("z_decompress%d: inflate returned %d (%s)\n",
 533                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 534             m_freem(mo_head);
 535             return DECOMP_FATALERROR;
 536         }
 537         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 538             break;              /* all done */
 539         if (state->strm.avail_in == 0 && mi != NULL) {
 540             state->strm.next_in = mtod(mi, u_char *);
 541             state->strm.avail_in = mi->m_len;
 542             rlen += mi->m_len;
 543             mi = mi->m_next;
 544             if (mi == NULL)
 545                 flush = Z_PACKET_FLUSH;
 546         }
 547         if (state->strm.avail_out == 0) {
 548             if (decode_proto) {
 549                 state->strm.avail_out = ospace - PPP_HDRLEN;
 550                 if ((wptr[3] & 1) == 0) {
 551                     /* 2-byte protocol field */
 552                     wptr[2] = wptr[3];
 553                     --state->strm.next_out;
 554                     ++state->strm.avail_out;
 555                     --olen;
 556                 }
 557                 decode_proto = 0;
 558             } else {
 559                 mo->m_len = ospace;
 560                 olen += ospace;
 561                 MGET(mo->m_next, M_NOWAIT, MT_DATA);
 562                 mo = mo->m_next;
 563                 if (mo == NULL) {
 564                     m_freem(mo_head);
 565                     return DECOMP_ERROR;
 566                 }
 567                 MCLGET(mo, M_NOWAIT);
 568                 state->strm.next_out = mtod(mo, u_char *);
 569                 state->strm.avail_out = ospace = M_TRAILINGSPACE(mo);
 570             }
 571         }
 572     }
 573     if (decode_proto) {
 574         m_freem(mo_head);
 575         return DECOMP_ERROR;
 576     }
 577     olen += (mo->m_len = ospace - state->strm.avail_out);
 578 #if DEFLATE_DEBUG
 579     if (state->debug && olen > state->mru + PPP_HDRLEN)
 580         kprintf("ppp_deflate%d: exceeded mru (%d > %d)\n",
 581                state->unit, olen, state->mru + PPP_HDRLEN);
 582 #endif
 583
 584     state->stats.unc_bytes += olen;
 585     state->stats.unc_packets++;
 586     state->stats.comp_bytes += rlen;
 587     state->stats.comp_packets++;
 588
 589     *mop = mo_head;
 590     return DECOMP_OK;
 591 }
 592
 593 /*
 594  * Incompressible data has arrived - add it to the history.
 595  */
 596 static void
 597 z_incomp(void *arg, struct mbuf *mi)
 598 {
 599     struct deflate_state *state = (struct deflate_state *) arg;
 600     u_char *rptr;
 601     int rlen, proto, r;
 602
 603     /*
 604      * Check that the protocol is one we handle.
 605      */
 606     rptr = mtod(mi, u_char *);
 607     proto = PPP_PROTOCOL(rptr);
 608     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
 609         return;
 610
 611     ++state->seqno;
 612
 613     /*
 614      * Iterate through the mbufs, adding the characters in them
 615      * to the decompressor's history.  For the first mbuf, we start
 616      * at the either the 1st or 2nd byte of the protocol field,
 617      * depending on whether the protocol value is compressible.
 618      */
 619     rlen = mi->m_len;
 620     state->strm.next_in = rptr + 3;
 621     state->strm.avail_in = rlen - 3;
 622     if (proto > 0xff) {
 623         --state->strm.next_in;
 624         ++state->strm.avail_in;
 625     }
 626     for (;;) {
 627         r = inflateIncomp(&state->strm);
 628         if (r != Z_OK) {
 629             /* gak! */
 630 #if !DEFLATE_DEBUG
 631             if (state->debug)
 632 #endif
 633                 kprintf("z_incomp%d: inflateIncomp returned %d (%s)\n",
 634                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 635             return;
 636         }
 637         mi = mi->m_next;
 638         if (mi == NULL)
 639             break;
 640         state->strm.next_in = mtod(mi, u_char *);
 641         state->strm.avail_in = mi->m_len;
 642         rlen += mi->m_len;
 643     }
 644
 645     /*
 646      * Update stats.
 647      */
 648     state->stats.inc_bytes += rlen;
 649     state->stats.inc_packets++;
 650     state->stats.unc_bytes += rlen;
 651     state->stats.unc_packets++;
 652 }
 653
 654 #endif /* DO_DEFLATE */