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 /* $DragonFly: src/sys/net/ppp_layer/ppp_deflate.c,v 1.9 2006/12/22 23:44:57 swildner 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) 1994 The Australian National University.
  10  * All rights reserved.
  11  *
  12  * Permission to use, copy, modify, and distribute this software and its
  13  * documentation is hereby granted, provided that the above copyright
  14  * notice appears in all copies.  This software is provided without any
  15  * warranty, express or implied. The Australian National University
  16  * makes no representations about the suitability of this software for
  17  * any purpose.
  18  *
  19  * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
  20  * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  21  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
  22  * THE AUSTRALIAN NATIONAL UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY
  23  * OF SUCH DAMAGE.
  24  *
  25  * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
  26  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  27  * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  28  * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
  29  * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
  30  * OR MODIFICATIONS.
  31  */
  32
  33 #include <sys/param.h>
  34 #include <sys/systm.h>
  35 #include <sys/malloc.h>
  36 #include <sys/mbuf.h>
  37 #include "ppp_defs.h"
  38 #include <net/zlib.h>
  39
  40 #define PACKETPTR       struct mbuf *
  41 #include "ppp_comp.h"
  42
  43 #if DO_DEFLATE
  44
  45 #define DEFLATE_DEBUG   1
  46
  47 /*
  48  * State for a Deflate (de)compressor.
  49  */
  50 struct deflate_state {
  51     int         seqno;
  52     int         w_size;
  53     int         unit;
  54     int         hdrlen;
  55     int         mru;
  56     int         debug;
  57     z_stream    strm;
  58     struct compstat stats;
  59 };
  60
  61 #define DEFLATE_OVHD    2               /* Deflate overhead/packet */
  62
  63 static void     *z_alloc (void *, u_int items, u_int size);
  64 static void     z_free (void *, void *ptr);
  65 static void     *z_comp_alloc (u_char *options, int opt_len);
  66 static void     *z_decomp_alloc (u_char *options, int opt_len);
  67 static void     z_comp_free (void *state);
  68 static void     z_decomp_free (void *state);
  69 static int      z_comp_init (void *state, u_char *options, int opt_len,
  70                                  int unit, int hdrlen, int debug);
  71 static int      z_decomp_init (void *state, u_char *options, int opt_len,
  72                                      int unit, int hdrlen, int mru, int debug);
  73 static int      z_compress (void *state, struct mbuf **mret,
  74                                   struct mbuf *mp, int slen, int maxolen);
  75 static void     z_incomp (void *state, struct mbuf *dmsg);
  76 static int      z_decompress (void *state, struct mbuf *cmp,
  77                                     struct mbuf **dmpp);
  78 static void     z_comp_reset (void *state);
  79 static void     z_decomp_reset (void *state);
  80 static void     z_comp_stats (void *state, struct compstat *stats);
  81
  82 /*
  83  * Procedures exported to if_ppp.c.
  84  */
  85 struct compressor ppp_deflate = {
  86     CI_DEFLATE,                 /* compress_proto */
  87     z_comp_alloc,               /* comp_alloc */
  88     z_comp_free,                /* comp_free */
  89     z_comp_init,                /* comp_init */
  90     z_comp_reset,               /* comp_reset */
  91     z_compress,                 /* compress */
  92     z_comp_stats,               /* comp_stat */
  93     z_decomp_alloc,             /* decomp_alloc */
  94     z_decomp_free,              /* decomp_free */
  95     z_decomp_init,              /* decomp_init */
  96     z_decomp_reset,             /* decomp_reset */
  97     z_decompress,               /* decompress */
  98     z_incomp,                   /* incomp */
  99     z_comp_stats,               /* decomp_stat */
 100 };
 101
 102 struct compressor ppp_deflate_draft = {
 103     CI_DEFLATE_DRAFT,           /* compress_proto */
 104     z_comp_alloc,               /* comp_alloc */
 105     z_comp_free,                /* comp_free */
 106     z_comp_init,                /* comp_init */
 107     z_comp_reset,               /* comp_reset */
 108     z_compress,                 /* compress */
 109     z_comp_stats,               /* comp_stat */
 110     z_decomp_alloc,             /* decomp_alloc */
 111     z_decomp_free,              /* decomp_free */
 112     z_decomp_init,              /* decomp_init */
 113     z_decomp_reset,             /* decomp_reset */
 114     z_decompress,               /* decompress */
 115     z_incomp,                   /* incomp */
 116     z_comp_stats,               /* decomp_stat */
 117 };
 118
 119 /*
 120  * Space allocation and freeing routines for use by zlib routines.
 121  */
 122 void *
 123 z_alloc(void *notused, u_int items, u_int size)
 124 {
 125     void *ptr;
 126
 127     MALLOC(ptr, void *, items * size, M_DEVBUF, M_WAITOK);
 128     return ptr;
 129 }
 130
 131 void
 132 z_free(void *notused, void *ptr)
 133 {
 134     kfree(ptr, M_DEVBUF);
 135 }
 136
 137 /*
 138  * Allocate space for a compressor.
 139  */
 140 static void *
 141 z_comp_alloc(u_char *options, int opt_len)
 142 {
 143     struct deflate_state *state;
 144     int w_size;
 145
 146     if (opt_len != CILEN_DEFLATE
 147         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 148         || options[1] != CILEN_DEFLATE
 149         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 150         || options[3] != DEFLATE_CHK_SEQUENCE)
 151         return NULL;
 152     w_size = DEFLATE_SIZE(options[2]);
 153     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
 154         return NULL;
 155
 156     MALLOC(state, struct deflate_state *, sizeof(struct deflate_state),
 157            M_DEVBUF, M_WAITOK);
 158
 159     state->strm.next_in = NULL;
 160     state->strm.zalloc = z_alloc;
 161     state->strm.zfree = z_free;
 162     if (deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION, DEFLATE_METHOD_VAL,
 163                      -w_size, 8, Z_DEFAULT_STRATEGY) != Z_OK) {
 164         kfree(state, M_DEVBUF);
 165         return NULL;
 166     }
 167
 168     state->w_size = w_size;
 169     bzero(&state->stats, sizeof(state->stats));
 170     return (void *) state;
 171 }
 172
 173 static void
 174 z_comp_free(void *arg)
 175 {
 176     struct deflate_state *state = (struct deflate_state *) arg;
 177
 178     deflateEnd(&state->strm);
 179     kfree(state, M_DEVBUF);
 180 }
 181
 182 static int
 183 z_comp_init(void *arg, u_char *options, int opt_len, int unit, int hdrlen,
 184             int debug)
 185 {
 186     struct deflate_state *state = (struct deflate_state *) arg;
 187
 188     if (opt_len < CILEN_DEFLATE
 189         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 190         || options[1] != CILEN_DEFLATE
 191         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 192         || DEFLATE_SIZE(options[2]) != state->w_size
 193         || options[3] != DEFLATE_CHK_SEQUENCE)
 194         return 0;
 195
 196     state->seqno = 0;
 197     state->unit = unit;
 198     state->hdrlen = hdrlen;
 199     state->debug = debug;
 200
 201     deflateReset(&state->strm);
 202
 203     return 1;
 204 }
 205
 206 static void
 207 z_comp_reset(void *arg)
 208 {
 209     struct deflate_state *state = (struct deflate_state *) arg;
 210
 211     state->seqno = 0;
 212     deflateReset(&state->strm);
 213 }
 214
 215 /*
 216  * Parameters:
 217  *      mret:   compressed packet (out)
 218  *      mp:     uncompressed packet (in)
 219  */
 220 int
 221 z_compress(void *arg, struct mbuf **mret, struct mbuf *mp, int orig_len,
 222            int maxolen)
 223 {
 224     struct deflate_state *state = (struct deflate_state *) arg;
 225     u_char *rptr, *wptr;
 226     int proto, olen, wspace, r, flush;
 227     struct mbuf *m;
 228
 229     /*
 230      * Check that the protocol is in the range we handle.
 231      */
 232     rptr = mtod(mp, u_char *);
 233     proto = PPP_PROTOCOL(rptr);
 234     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb) {
 235         *mret = NULL;
 236         return orig_len;
 237     }
 238
 239     /* Allocate one mbuf initially. */
 240     if (maxolen > orig_len)
 241         maxolen = orig_len;
 242     MGET(m, MB_DONTWAIT, MT_DATA);
 243     *mret = m;
 244     if (m != NULL) {
 245         m->m_len = 0;
 246         if (maxolen + state->hdrlen > MLEN)
 247             MCLGET(m, MB_DONTWAIT);
 248         wspace = M_TRAILINGSPACE(m);
 249         if (state->hdrlen + PPP_HDRLEN + 2 < wspace) {
 250             m->m_data += state->hdrlen;
 251             wspace -= state->hdrlen;
 252         }
 253         wptr = mtod(m, u_char *);
 254
 255         /*
 256          * Copy over the PPP header and store the 2-byte sequence number.
 257          */
 258         wptr[0] = PPP_ADDRESS(rptr);
 259         wptr[1] = PPP_CONTROL(rptr);
 260         wptr[2] = PPP_COMP >> 8;
 261         wptr[3] = PPP_COMP;
 262         wptr += PPP_HDRLEN;
 263         wptr[0] = state->seqno >> 8;
 264         wptr[1] = state->seqno;
 265         wptr += 2;
 266         state->strm.next_out = wptr;
 267         state->strm.avail_out = wspace - (PPP_HDRLEN + 2);
 268     } else {
 269         state->strm.next_out = NULL;
 270         state->strm.avail_out = 1000000;
 271         wptr = NULL;
 272         wspace = 0;
 273     }
 274     ++state->seqno;
 275
 276     rptr += (proto > 0xff)? 2: 3;       /* skip 1st proto byte if 0 */
 277     state->strm.next_in = rptr;
 278     state->strm.avail_in = mtod(mp, u_char *) + mp->m_len - rptr;
 279     mp = mp->m_next;
 280     flush = (mp == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 281     olen = 0;
 282     for (;;) {
 283         r = deflate(&state->strm, flush);
 284         if (r != Z_OK) {
 285             kprintf("z_compress: deflate returned %d (%s)\n",
 286                    r, (state->strm.msg? state->strm.msg: ""));
 287             break;
 288         }
 289         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 290             break;              /* all done */
 291         if (state->strm.avail_in == 0 && mp != NULL) {
 292             state->strm.next_in = mtod(mp, u_char *);
 293             state->strm.avail_in = mp->m_len;
 294             mp = mp->m_next;
 295             if (mp == NULL)
 296                 flush = Z_PACKET_FLUSH;
 297         }
 298         if (state->strm.avail_out == 0) {
 299             if (m != NULL) {
 300                 m->m_len = wspace;
 301                 olen += wspace;
 302                 MGET(m->m_next, MB_DONTWAIT, MT_DATA);
 303                 m = m->m_next;
 304                 if (m != NULL) {
 305                     m->m_len = 0;
 306                     if (maxolen - olen > MLEN)
 307                         MCLGET(m, MB_DONTWAIT);
 308                     state->strm.next_out = mtod(m, u_char *);
 309                     state->strm.avail_out = wspace = M_TRAILINGSPACE(m);
 310                 }
 311             }
 312             if (m == NULL) {
 313                 state->strm.next_out = NULL;
 314                 state->strm.avail_out = 1000000;
 315             }
 316         }
 317     }
 318     if (m != NULL)
 319         olen += (m->m_len = wspace - state->strm.avail_out);
 320
 321     /*
 322      * See if we managed to reduce the size of the packet.
 323      */
 324     if (m != NULL && olen < orig_len) {
 325         state->stats.comp_bytes += olen;
 326         state->stats.comp_packets++;
 327     } else {
 328         if (*mret != NULL) {
 329             m_freem(*mret);
 330             *mret = NULL;
 331         }
 332         state->stats.inc_bytes += orig_len;
 333         state->stats.inc_packets++;
 334         olen = orig_len;
 335     }
 336     state->stats.unc_bytes += orig_len;
 337     state->stats.unc_packets++;
 338
 339     return olen;
 340 }
 341
 342 static void
 343 z_comp_stats(void *arg, struct compstat *stats)
 344 {
 345     struct deflate_state *state = (struct deflate_state *) arg;
 346     u_int out;
 347
 348     *stats = state->stats;
 349     stats->ratio = stats->unc_bytes;
 350     out = stats->comp_bytes + stats->inc_bytes;
 351     if (stats->ratio <= 0x7ffffff)
 352         stats->ratio <<= 8;
 353     else
 354         out >>= 8;
 355     if (out != 0)
 356         stats->ratio /= out;
 357 }
 358
 359 /*
 360  * Allocate space for a decompressor.
 361  */
 362 static void *
 363 z_decomp_alloc(u_char *options, int opt_len)
 364 {
 365     struct deflate_state *state;
 366     int w_size;
 367
 368     if (opt_len != CILEN_DEFLATE
 369         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 370         || options[1] != CILEN_DEFLATE
 371         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 372         || options[3] != DEFLATE_CHK_SEQUENCE)
 373         return NULL;
 374     w_size = DEFLATE_SIZE(options[2]);
 375     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
 376         return NULL;
 377
 378     MALLOC(state, struct deflate_state *, sizeof(struct deflate_state),
 379            M_DEVBUF, M_WAITOK);
 380
 381     state->strm.next_out = NULL;
 382     state->strm.zalloc = z_alloc;
 383     state->strm.zfree = z_free;
 384     if (inflateInit2(&state->strm, -w_size) != Z_OK) {
 385         kfree(state, M_DEVBUF);
 386         return NULL;
 387     }
 388
 389     state->w_size = w_size;
 390     bzero(&state->stats, sizeof(state->stats));
 391     return (void *) state;
 392 }
 393
 394 static void
 395 z_decomp_free(void *arg)
 396 {
 397     struct deflate_state *state = (struct deflate_state *) arg;
 398
 399     inflateEnd(&state->strm);
 400     kfree(state, M_DEVBUF);
 401 }
 402
 403 static int
 404 z_decomp_init(void *arg, u_char *options, int opt_len, int unit, int hdrlen,
 405               int mru, int debug)
 406 {
 407     struct deflate_state *state = (struct deflate_state *) arg;
 408
 409     if (opt_len < CILEN_DEFLATE
 410         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 411         || options[1] != CILEN_DEFLATE
 412         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 413         || DEFLATE_SIZE(options[2]) != state->w_size
 414         || options[3] != DEFLATE_CHK_SEQUENCE)
 415         return 0;
 416
 417     state->seqno = 0;
 418     state->unit = unit;
 419     state->hdrlen = hdrlen;
 420     state->debug = debug;
 421     state->mru = mru;
 422
 423     inflateReset(&state->strm);
 424
 425     return 1;
 426 }
 427
 428 static void
 429 z_decomp_reset(void *arg)
 430 {
 431     struct deflate_state *state = (struct deflate_state *) arg;
 432
 433     state->seqno = 0;
 434     inflateReset(&state->strm);
 435 }
 436
 437 /*
 438  * Decompress a Deflate-compressed packet.
 439  *
 440  * Because of patent problems, we return DECOMP_ERROR for errors
 441  * found by inspecting the input data and for system problems, but
 442  * DECOMP_FATALERROR for any errors which could possibly be said to
 443  * be being detected "after" decompression.  For DECOMP_ERROR,
 444  * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
 445  * infringing a patent of Motorola's if we do, so we take CCP down
 446  * instead.
 447  *
 448  * Given that the frame has the correct sequence number and a good FCS,
 449  * errors such as invalid codes in the input most likely indicate a
 450  * bug, so we return DECOMP_FATALERROR for them in order to turn off
 451  * compression, even though they are detected by inspecting the input.
 452  */
 453 int
 454 z_decompress(void *arg, struct mbuf *mi, struct mbuf **mop)
 455 {
 456     struct deflate_state *state = (struct deflate_state *) arg;
 457     struct mbuf *mo, *mo_head;
 458     u_char *rptr, *wptr;
 459     int rlen, olen, ospace;
 460     int seq, i, flush, r, decode_proto;
 461     u_char hdr[PPP_HDRLEN + DEFLATE_OVHD];
 462
 463     *mop = NULL;
 464     rptr = mtod(mi, u_char *);
 465     rlen = mi->m_len;
 466     for (i = 0; i < PPP_HDRLEN + DEFLATE_OVHD; ++i) {
 467         while (rlen <= 0) {
 468             mi = mi->m_next;
 469             if (mi == NULL)
 470                 return DECOMP_ERROR;
 471             rptr = mtod(mi, u_char *);
 472             rlen = mi->m_len;
 473         }
 474         hdr[i] = *rptr++;
 475         --rlen;
 476     }
 477
 478     /* Check the sequence number. */
 479     seq = (hdr[PPP_HDRLEN] << 8) + hdr[PPP_HDRLEN+1];
 480     if (seq != state->seqno) {
 481         if (state->debug)
 482             kprintf("z_decompress%d: bad seq # %d, expected %d\n",
 483                    state->unit, seq, state->seqno);
 484         return DECOMP_ERROR;
 485     }
 486     ++state->seqno;
 487
 488     /* Allocate an output mbuf. */
 489     MGETHDR(mo, MB_DONTWAIT, MT_DATA);
 490     if (mo == NULL)
 491         return DECOMP_ERROR;
 492     mo_head = mo;
 493     mo->m_len = 0;
 494     mo->m_next = NULL;
 495     MCLGET(mo, MB_DONTWAIT);
 496     ospace = M_TRAILINGSPACE(mo);
 497     if (state->hdrlen + PPP_HDRLEN < ospace) {
 498         mo->m_data += state->hdrlen;
 499         ospace -= state->hdrlen;
 500     }
 501
 502     /*
 503      * Fill in the first part of the PPP header.  The protocol field
 504      * comes from the decompressed data.
 505      */
 506     wptr = mtod(mo, u_char *);
 507     wptr[0] = PPP_ADDRESS(hdr);
 508     wptr[1] = PPP_CONTROL(hdr);
 509     wptr[2] = 0;
 510
 511     /*
 512      * Set up to call inflate.  We set avail_out to 1 initially so we can
 513      * look at the first byte of the output and decide whether we have
 514      * a 1-byte or 2-byte protocol field.
 515      */
 516     state->strm.next_in = rptr;
 517     state->strm.avail_in = rlen;
 518     mi = mi->m_next;
 519     flush = (mi == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 520     rlen += PPP_HDRLEN + DEFLATE_OVHD;
 521     state->strm.next_out = wptr + 3;
 522     state->strm.avail_out = 1;
 523     decode_proto = 1;
 524     olen = PPP_HDRLEN;
 525
 526     /*
 527      * Call inflate, supplying more input or output as needed.
 528      */
 529     for (;;) {
 530         r = inflate(&state->strm, flush);
 531         if (r != Z_OK) {
 532 #if !DEFLATE_DEBUG
 533             if (state->debug)
 534 #endif
 535                 kprintf("z_decompress%d: inflate returned %d (%s)\n",
 536                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 537             m_freem(mo_head);
 538             return DECOMP_FATALERROR;
 539         }
 540         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 541             break;              /* all done */
 542         if (state->strm.avail_in == 0 && mi != NULL) {
 543             state->strm.next_in = mtod(mi, u_char *);
 544             state->strm.avail_in = mi->m_len;
 545             rlen += mi->m_len;
 546             mi = mi->m_next;
 547             if (mi == NULL)
 548                 flush = Z_PACKET_FLUSH;
 549         }
 550         if (state->strm.avail_out == 0) {
 551             if (decode_proto) {
 552                 state->strm.avail_out = ospace - PPP_HDRLEN;
 553                 if ((wptr[3] & 1) == 0) {
 554                     /* 2-byte protocol field */
 555                     wptr[2] = wptr[3];
 556                     --state->strm.next_out;
 557                     ++state->strm.avail_out;
 558                     --olen;
 559                 }
 560                 decode_proto = 0;
 561             } else {
 562                 mo->m_len = ospace;
 563                 olen += ospace;
 564                 MGET(mo->m_next, MB_DONTWAIT, MT_DATA);
 565                 mo = mo->m_next;
 566                 if (mo == NULL) {
 567                     m_freem(mo_head);
 568                     return DECOMP_ERROR;
 569                 }
 570                 MCLGET(mo, MB_DONTWAIT);
 571                 state->strm.next_out = mtod(mo, u_char *);
 572                 state->strm.avail_out = ospace = M_TRAILINGSPACE(mo);
 573             }
 574         }
 575     }
 576     if (decode_proto) {
 577         m_freem(mo_head);
 578         return DECOMP_ERROR;
 579     }
 580     olen += (mo->m_len = ospace - state->strm.avail_out);
 581 #if DEFLATE_DEBUG
 582     if (state->debug && olen > state->mru + PPP_HDRLEN)
 583         kprintf("ppp_deflate%d: exceeded mru (%d > %d)\n",
 584                state->unit, olen, state->mru + PPP_HDRLEN);
 585 #endif
 586
 587     state->stats.unc_bytes += olen;
 588     state->stats.unc_packets++;
 589     state->stats.comp_bytes += rlen;
 590     state->stats.comp_packets++;
 591
 592     *mop = mo_head;
 593     return DECOMP_OK;
 594 }
 595
 596 /*
 597  * Incompressible data has arrived - add it to the history.
 598  */
 599 static void
 600 z_incomp(void *arg, struct mbuf *mi)
 601 {
 602     struct deflate_state *state = (struct deflate_state *) arg;
 603     u_char *rptr;
 604     int rlen, proto, r;
 605
 606     /*
 607      * Check that the protocol is one we handle.
 608      */
 609     rptr = mtod(mi, u_char *);
 610     proto = PPP_PROTOCOL(rptr);
 611     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
 612         return;
 613
 614     ++state->seqno;
 615
 616     /*
 617      * Iterate through the mbufs, adding the characters in them
 618      * to the decompressor's history.  For the first mbuf, we start
 619      * at the either the 1st or 2nd byte of the protocol field,
 620      * depending on whether the protocol value is compressible.
 621      */
 622     rlen = mi->m_len;
 623     state->strm.next_in = rptr + 3;
 624     state->strm.avail_in = rlen - 3;
 625     if (proto > 0xff) {
 626         --state->strm.next_in;
 627         ++state->strm.avail_in;
 628     }
 629     for (;;) {
 630         r = inflateIncomp(&state->strm);
 631         if (r != Z_OK) {
 632             /* gak! */
 633 #if !DEFLATE_DEBUG
 634             if (state->debug)
 635 #endif
 636                 kprintf("z_incomp%d: inflateIncomp returned %d (%s)\n",
 637                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 638             return;
 639         }
 640         mi = mi->m_next;
 641         if (mi == NULL)
 642             break;
 643         state->strm.next_in = mtod(mi, u_char *);
 644         state->strm.avail_in = mi->m_len;
 645         rlen += mi->m_len;
 646     }
 647
 648     /*
 649      * Update stats.
 650      */
 651     state->stats.inc_bytes += rlen;
 652     state->stats.inc_packets++;
 653     state->stats.unc_bytes += rlen;
 654     state->stats.unc_packets++;
 655 }
 656
 657 #endif /* DO_DEFLATE */