release/src/router/ppp/modules/deflate.c

   1 /*
   2  * ppp_deflate.c - interface the zlib procedures for Deflate compression
   3  * and decompression (as used by gzip) to the PPP code.
   4  * This version is for use with STREAMS under SunOS 4.x, Solaris 2,
   5  * SVR4, OSF/1 and AIX 4.x.
   6  *
   7  * Copyright (c) 1994 The Australian National University.
   8  * All rights reserved.
   9  *
  10  * Permission to use, copy, modify, and distribute this software and its
  11  * documentation is hereby granted, provided that the above copyright
  12  * notice appears in all copies.  This software is provided without any
  13  * warranty, express or implied. The Australian National University
  14  * makes no representations about the suitability of this software for
  15  * any purpose.
  16  *
  17  * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
  18  * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  19  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
  20  * THE AUSTRALIAN NATIONAL UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY
  21  * OF SUCH DAMAGE.
  22  *
  23  * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
  24  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  25  * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  26  * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
  27  * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
  28  * OR MODIFICATIONS.
  29  *
  30  * $Id: deflate.c,v 1.1.1.4 2003/10/14 08:09:53 sparq Exp $
  31  */
  32
  33 #ifdef AIX4
  34 #include <net/net_globals.h>
  35 #endif
  36 #include <sys/param.h>
  37 #include <sys/types.h>
  38 #include <sys/stream.h>
  39 #include <net/ppp_defs.h>
  40 #include "ppp_mod.h"
  41
  42 #define PACKETPTR       mblk_t *
  43 #include <net/ppp-comp.h>
  44
  45 #ifdef __osf__
  46 #include "zlib.h"
  47 #else
  48 #include "../common/zlib.h"
  49 #endif
  50
  51 #if DO_DEFLATE
  52
  53 #define DEFLATE_DEBUG   1
  54
  55 /*
  56  * State for a Deflate (de)compressor.
  57  */
  58 struct deflate_state {
  59     int         seqno;
  60     int         w_size;
  61     int         unit;
  62     int         hdrlen;
  63     int         mru;
  64     int         debug;
  65     z_stream    strm;
  66     struct compstat stats;
  67 };
  68
  69 #define DEFLATE_OVHD    2               /* Deflate overhead/packet */
  70
  71 static void     *z_alloc __P((void *, u_int items, u_int size));
  72 static void     *z_alloc_init __P((void *, u_int items, u_int size));
  73 static void     z_free __P((void *, void *ptr));
  74 static void     *z_comp_alloc __P((u_char *options, int opt_len));
  75 static void     *z_decomp_alloc __P((u_char *options, int opt_len));
  76 static void     z_comp_free __P((void *state));
  77 static void     z_decomp_free __P((void *state));
  78 static int      z_comp_init __P((void *state, u_char *options, int opt_len,
  79                                  int unit, int hdrlen, int debug));
  80 static int      z_decomp_init __P((void *state, u_char *options, int opt_len,
  81                                      int unit, int hdrlen, int mru, int debug));
  82 static int      z_compress __P((void *state, mblk_t **mret,
  83                                   mblk_t *mp, int slen, int maxolen));
  84 static void     z_incomp __P((void *state, mblk_t *dmsg));
  85 static int      z_decompress __P((void *state, mblk_t *cmp,
  86                                     mblk_t **dmpp));
  87 static void     z_comp_reset __P((void *state));
  88 static void     z_decomp_reset __P((void *state));
  89 static void     z_comp_stats __P((void *state, struct compstat *stats));
  90
  91 /*
  92  * Procedures exported to ppp_comp.c.
  93  */
  94 struct compressor ppp_deflate = {
  95     CI_DEFLATE,                 /* compress_proto */
  96     z_comp_alloc,               /* comp_alloc */
  97     z_comp_free,                /* comp_free */
  98     z_comp_init,                /* comp_init */
  99     z_comp_reset,               /* comp_reset */
 100     z_compress,                 /* compress */
 101     z_comp_stats,               /* comp_stat */
 102     z_decomp_alloc,             /* decomp_alloc */
 103     z_decomp_free,              /* decomp_free */
 104     z_decomp_init,              /* decomp_init */
 105     z_decomp_reset,             /* decomp_reset */
 106     z_decompress,               /* decompress */
 107     z_incomp,                   /* incomp */
 108     z_comp_stats,               /* decomp_stat */
 109 };
 110
 111 struct compressor ppp_deflate_draft = {
 112     CI_DEFLATE_DRAFT,           /* compress_proto */
 113     z_comp_alloc,               /* comp_alloc */
 114     z_comp_free,                /* comp_free */
 115     z_comp_init,                /* comp_init */
 116     z_comp_reset,               /* comp_reset */
 117     z_compress,                 /* compress */
 118     z_comp_stats,               /* comp_stat */
 119     z_decomp_alloc,             /* decomp_alloc */
 120     z_decomp_free,              /* decomp_free */
 121     z_decomp_init,              /* decomp_init */
 122     z_decomp_reset,             /* decomp_reset */
 123     z_decompress,               /* decompress */
 124     z_incomp,                   /* incomp */
 125     z_comp_stats,               /* decomp_stat */
 126 };
 127
 128 #define DECOMP_CHUNK    512
 129
 130 /*
 131  * Space allocation and freeing routines for use by zlib routines.
 132  */
 133 struct zchunk {
 134     u_int       size;
 135     u_int       guard;
 136 };
 137
 138 #define GUARD_MAGIC     0x77a6011a
 139
 140 static void *
 141 z_alloc_init(notused, items, size)
 142     void *notused;
 143     u_int items, size;
 144 {
 145     struct zchunk *z;
 146
 147     size = items * size + sizeof(struct zchunk);
 148 #ifdef __osf__
 149     z = (struct zchunk *) ALLOC_SLEEP(size);
 150 #else
 151     z = (struct zchunk *) ALLOC_NOSLEEP(size);
 152 #endif
 153     z->size = size;
 154     z->guard = GUARD_MAGIC;
 155     return (void *) (z + 1);
 156 }
 157
 158 static void *
 159 z_alloc(notused, items, size)
 160     void *notused;
 161     u_int items, size;
 162 {
 163     struct zchunk *z;
 164
 165     size = items * size + sizeof(struct zchunk);
 166     z = (struct zchunk *) ALLOC_NOSLEEP(size);
 167     z->size = size;
 168     z->guard = GUARD_MAGIC;
 169     return (void *) (z + 1);
 170 }
 171
 172 static void
 173 z_free(notused, ptr)
 174     void *notused;
 175     void *ptr;
 176 {
 177     struct zchunk *z = ((struct zchunk *) ptr) - 1;
 178
 179     if (z->guard != GUARD_MAGIC) {
 180         printf("ppp: z_free of corrupted chunk at %x (%x, %x)\n",
 181                z, z->size, z->guard);
 182         return;
 183     }
 184     FREE(z, z->size);
 185 }
 186
 187 /*
 188  * Allocate space for a compressor.
 189  */
 190 static void *
 191 z_comp_alloc(options, opt_len)
 192     u_char *options;
 193     int opt_len;
 194 {
 195     struct deflate_state *state;
 196     int w_size;
 197
 198     if (opt_len != CILEN_DEFLATE
 199         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 200         || options[1] != CILEN_DEFLATE
 201         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 202         || options[3] != DEFLATE_CHK_SEQUENCE)
 203         return NULL;
 204     w_size = DEFLATE_SIZE(options[2]);
 205     /*
 206      * N.B. the 9 below should be DEFLATE_MIN_SIZE (8), but using
 207      * 8 will cause kernel crashes because of a bug in zlib.
 208      */
 209     if (w_size < 9 || w_size > DEFLATE_MAX_SIZE)
 210         return NULL;
 211
 212
 213 #ifdef __osf__
 214     state = (struct deflate_state *) ALLOC_SLEEP(sizeof(*state));
 215 #else
 216     state = (struct deflate_state *) ALLOC_NOSLEEP(sizeof(*state));
 217 #endif
 218
 219     if (state == NULL)
 220         return NULL;
 221
 222     state->strm.next_in = NULL;
 223     state->strm.zalloc = (alloc_func) z_alloc_init;
 224     state->strm.zfree = (free_func) z_free;
 225     if (deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION, DEFLATE_METHOD_VAL,
 226                      -w_size, 8, Z_DEFAULT_STRATEGY) != Z_OK) {
 227         FREE(state, sizeof(*state));
 228         return NULL;
 229     }
 230
 231     state->strm.zalloc = (alloc_func) z_alloc;
 232     state->w_size = w_size;
 233     bzero(&state->stats, sizeof(state->stats));
 234     return (void *) state;
 235 }
 236
 237 static void
 238 z_comp_free(arg)
 239     void *arg;
 240 {
 241     struct deflate_state *state = (struct deflate_state *) arg;
 242
 243     deflateEnd(&state->strm);
 244     FREE(state, sizeof(*state));
 245 }
 246
 247 static int
 248 z_comp_init(arg, options, opt_len, unit, hdrlen, debug)
 249     void *arg;
 250     u_char *options;
 251     int opt_len, unit, hdrlen, debug;
 252 {
 253     struct deflate_state *state = (struct deflate_state *) arg;
 254
 255     if (opt_len < CILEN_DEFLATE
 256         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 257         || options[1] != CILEN_DEFLATE
 258         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 259         || DEFLATE_SIZE(options[2]) != state->w_size
 260         || options[3] != DEFLATE_CHK_SEQUENCE)
 261         return 0;
 262
 263     state->seqno = 0;
 264     state->unit = unit;
 265     state->hdrlen = hdrlen;
 266     state->debug = debug;
 267
 268     deflateReset(&state->strm);
 269
 270     return 1;
 271 }
 272
 273 static void
 274 z_comp_reset(arg)
 275     void *arg;
 276 {
 277     struct deflate_state *state = (struct deflate_state *) arg;
 278
 279     state->seqno = 0;
 280     deflateReset(&state->strm);
 281 }
 282
 283 static int
 284 z_compress(arg, mret, mp, orig_len, maxolen)
 285     void *arg;
 286     mblk_t **mret;              /* compressed packet (out) */
 287     mblk_t *mp;         /* uncompressed packet (in) */
 288     int orig_len, maxolen;
 289 {
 290     struct deflate_state *state = (struct deflate_state *) arg;
 291     u_char *rptr, *wptr;
 292     int proto, olen, wspace, r, flush;
 293     mblk_t *m;
 294
 295     /*
 296      * Check that the protocol is in the range we handle.
 297      */
 298     *mret = NULL;
 299     rptr = mp->b_rptr;
 300     if (rptr + PPP_HDRLEN > mp->b_wptr) {
 301         if (!pullupmsg(mp, PPP_HDRLEN))
 302             return 0;
 303         rptr = mp->b_rptr;
 304     }
 305     proto = PPP_PROTOCOL(rptr);
 306     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
 307         return orig_len;
 308
 309     /* Allocate one mblk initially. */
 310     if (maxolen > orig_len)
 311         maxolen = orig_len;
 312     if (maxolen <= PPP_HDRLEN + 2) {
 313         wspace = 0;
 314         m = NULL;
 315     } else {
 316         wspace = maxolen + state->hdrlen;
 317         if (wspace > 4096)
 318             wspace = 4096;
 319         m = allocb(wspace, BPRI_MED);
 320     }
 321     if (m != NULL) {
 322         *mret = m;
 323         if (state->hdrlen + PPP_HDRLEN + 2 < wspace) {
 324             m->b_rptr += state->hdrlen;
 325             m->b_wptr = m->b_rptr;
 326             wspace -= state->hdrlen;
 327         }
 328         wptr = m->b_wptr;
 329
 330         /*
 331          * Copy over the PPP header and store the 2-byte sequence number.
 332          */
 333         wptr[0] = PPP_ADDRESS(rptr);
 334         wptr[1] = PPP_CONTROL(rptr);
 335         wptr[2] = PPP_COMP >> 8;
 336         wptr[3] = PPP_COMP;
 337         wptr += PPP_HDRLEN;
 338         wptr[0] = state->seqno >> 8;
 339         wptr[1] = state->seqno;
 340         wptr += 2;
 341         state->strm.next_out = wptr;
 342         state->strm.avail_out = wspace - (PPP_HDRLEN + 2);
 343     } else {
 344         state->strm.next_out = NULL;
 345         state->strm.avail_out = 1000000;
 346     }
 347     ++state->seqno;
 348
 349     rptr += (proto > 0xff)? 2: 3;       /* skip 1st proto byte if 0 */
 350     state->strm.next_in = rptr;
 351     state->strm.avail_in = mp->b_wptr - rptr;
 352     mp = mp->b_cont;
 353     flush = (mp == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 354     olen = 0;
 355     for (;;) {
 356         r = deflate(&state->strm, flush);
 357         if (r != Z_OK) {
 358             printf("z_compress: deflate returned %d (%s)\n",
 359                    r, (state->strm.msg? state->strm.msg: ""));
 360             break;
 361         }
 362         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 363             break;              /* all done */
 364         if (state->strm.avail_in == 0 && mp != NULL) {
 365             state->strm.next_in = mp->b_rptr;
 366             state->strm.avail_in = mp->b_wptr - mp->b_rptr;
 367             mp = mp->b_cont;
 368             if (mp == NULL)
 369                 flush = Z_PACKET_FLUSH;
 370         }
 371         if (state->strm.avail_out == 0) {
 372             if (m != NULL) {
 373                 m->b_wptr += wspace;
 374                 olen += wspace;
 375                 wspace = maxolen - olen;
 376                 if (wspace <= 0) {
 377                     wspace = 0;
 378                     m->b_cont = NULL;
 379                 } else {
 380                     if (wspace < 32)
 381                         wspace = 32;
 382                     else if (wspace > 4096)
 383                         wspace = 4096;
 384                     m->b_cont = allocb(wspace, BPRI_MED);
 385                 }
 386                 m = m->b_cont;
 387                 if (m != NULL) {
 388                     state->strm.next_out = m->b_wptr;
 389                     state->strm.avail_out = wspace;
 390                 }
 391             }
 392             if (m == NULL) {
 393                 state->strm.next_out = NULL;
 394                 state->strm.avail_out = 1000000;
 395             }
 396         }
 397     }
 398     if (m != NULL) {
 399         m->b_wptr += wspace - state->strm.avail_out;
 400         olen += wspace - state->strm.avail_out;
 401     }
 402
 403     /*
 404      * See if we managed to reduce the size of the packet.
 405      */
 406     if (olen < orig_len && m != NULL) {
 407         state->stats.comp_bytes += olen;
 408         state->stats.comp_packets++;
 409     } else {
 410         if (*mret != NULL) {
 411             freemsg(*mret);
 412             *mret = NULL;
 413         }
 414         state->stats.inc_bytes += orig_len;
 415         state->stats.inc_packets++;
 416         olen = orig_len;
 417     }
 418     state->stats.unc_bytes += orig_len;
 419     state->stats.unc_packets++;
 420
 421     return olen;
 422 }
 423
 424 static void
 425 z_comp_stats(arg, stats)
 426     void *arg;
 427     struct compstat *stats;
 428 {
 429     struct deflate_state *state = (struct deflate_state *) arg;
 430     u_int out;
 431
 432     *stats = state->stats;
 433     stats->ratio = stats->unc_bytes;
 434     out = stats->comp_bytes + stats->unc_bytes;
 435     if (stats->ratio <= 0x7ffffff)
 436         stats->ratio <<= 8;
 437     else
 438         out >>= 8;
 439     if (out != 0)
 440         stats->ratio /= out;
 441 }
 442
 443 /*
 444  * Allocate space for a decompressor.
 445  */
 446 static void *
 447 z_decomp_alloc(options, opt_len)
 448     u_char *options;
 449     int opt_len;
 450 {
 451     struct deflate_state *state;
 452     int w_size;
 453
 454     if (opt_len != CILEN_DEFLATE
 455         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 456         || options[1] != CILEN_DEFLATE
 457         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 458         || options[3] != DEFLATE_CHK_SEQUENCE)
 459         return NULL;
 460     w_size = DEFLATE_SIZE(options[2]);
 461     /*
 462      * N.B. the 9 below should be DEFLATE_MIN_SIZE (8), but using
 463      * 8 will cause kernel crashes because of a bug in zlib.
 464      */
 465     if (w_size < 9 || w_size > DEFLATE_MAX_SIZE)
 466         return NULL;
 467
 468 #ifdef __osf__
 469     state = (struct deflate_state *) ALLOC_SLEEP(sizeof(*state));
 470 #else
 471     state = (struct deflate_state *) ALLOC_NOSLEEP(sizeof(*state));
 472 #endif
 473     if (state == NULL)
 474         return NULL;
 475
 476     state->strm.next_out = NULL;
 477     state->strm.zalloc = (alloc_func) z_alloc_init;
 478     state->strm.zfree = (free_func) z_free;
 479     if (inflateInit2(&state->strm, -w_size) != Z_OK) {
 480         FREE(state, sizeof(*state));
 481         return NULL;
 482     }
 483
 484     state->strm.zalloc = (alloc_func) z_alloc;
 485     state->w_size = w_size;
 486     bzero(&state->stats, sizeof(state->stats));
 487     return (void *) state;
 488 }
 489
 490 static void
 491 z_decomp_free(arg)
 492     void *arg;
 493 {
 494     struct deflate_state *state = (struct deflate_state *) arg;
 495
 496     inflateEnd(&state->strm);
 497     FREE(state, sizeof(*state));
 498 }
 499
 500 static int
 501 z_decomp_init(arg, options, opt_len, unit, hdrlen, mru, debug)
 502     void *arg;
 503     u_char *options;
 504     int opt_len, unit, hdrlen, mru, debug;
 505 {
 506     struct deflate_state *state = (struct deflate_state *) arg;
 507
 508     if (opt_len < CILEN_DEFLATE
 509         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 510         || options[1] != CILEN_DEFLATE
 511         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 512         || DEFLATE_SIZE(options[2]) != state->w_size
 513         || options[3] != DEFLATE_CHK_SEQUENCE)
 514         return 0;
 515
 516     state->seqno = 0;
 517     state->unit = unit;
 518     state->hdrlen = hdrlen;
 519     state->debug = debug;
 520     state->mru = mru;
 521
 522     inflateReset(&state->strm);
 523
 524     return 1;
 525 }
 526
 527 static void
 528 z_decomp_reset(arg)
 529     void *arg;
 530 {
 531     struct deflate_state *state = (struct deflate_state *) arg;
 532
 533     state->seqno = 0;
 534     inflateReset(&state->strm);
 535 }
 536
 537 /*
 538  * Decompress a Deflate-compressed packet.
 539  *
 540  * Because of patent problems, we return DECOMP_ERROR for errors
 541  * found by inspecting the input data and for system problems, but
 542  * DECOMP_FATALERROR for any errors which could possibly be said to
 543  * be being detected "after" decompression.  For DECOMP_ERROR,
 544  * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
 545  * infringing a patent of Motorola's if we do, so we take CCP down
 546  * instead.
 547  *
 548  * Given that the frame has the correct sequence number and a good FCS,
 549  * errors such as invalid codes in the input most likely indicate a
 550  * bug, so we return DECOMP_FATALERROR for them in order to turn off
 551  * compression, even though they are detected by inspecting the input.
 552  */
 553 static int
 554 z_decompress(arg, mi, mop)
 555     void *arg;
 556     mblk_t *mi, **mop;
 557 {
 558     struct deflate_state *state = (struct deflate_state *) arg;
 559     mblk_t *mo, *mo_head;
 560     u_char *rptr, *wptr;
 561     int rlen, olen, ospace;
 562     int seq, i, flush, r, decode_proto;
 563     u_char hdr[PPP_HDRLEN + DEFLATE_OVHD];
 564
 565     *mop = NULL;
 566     rptr = mi->b_rptr;
 567     for (i = 0; i < PPP_HDRLEN + DEFLATE_OVHD; ++i) {
 568         while (rptr >= mi->b_wptr) {
 569             mi = mi->b_cont;
 570             if (mi == NULL)
 571                 return DECOMP_ERROR;
 572             rptr = mi->b_rptr;
 573         }
 574         hdr[i] = *rptr++;
 575     }
 576
 577     /* Check the sequence number. */
 578     seq = (hdr[PPP_HDRLEN] << 8) + hdr[PPP_HDRLEN+1];
 579     if (seq != state->seqno) {
 580 #if !DEFLATE_DEBUG
 581         if (state->debug)
 582 #endif
 583             printf("z_decompress%d: bad seq # %d, expected %d\n",
 584                    state->unit, seq, state->seqno);
 585         return DECOMP_ERROR;
 586     }
 587     ++state->seqno;
 588
 589     /* Allocate an output message block. */
 590     mo = allocb(DECOMP_CHUNK + state->hdrlen, BPRI_MED);
 591     if (mo == NULL)
 592         return DECOMP_ERROR;
 593     mo_head = mo;
 594     mo->b_cont = NULL;
 595     mo->b_rptr += state->hdrlen;
 596     mo->b_wptr = wptr = mo->b_rptr;
 597     ospace = DECOMP_CHUNK;
 598     olen = 0;
 599
 600     /*
 601      * Fill in the first part of the PPP header.  The protocol field
 602      * comes from the decompressed data.
 603      */
 604     wptr[0] = PPP_ADDRESS(hdr);
 605     wptr[1] = PPP_CONTROL(hdr);
 606     wptr[2] = 0;
 607
 608     /*
 609      * Set up to call inflate.  We set avail_out to 1 initially so we can
 610      * look at the first byte of the output and decide whether we have
 611      * a 1-byte or 2-byte protocol field.
 612      */
 613     state->strm.next_in = rptr;
 614     state->strm.avail_in = mi->b_wptr - rptr;
 615     mi = mi->b_cont;
 616     flush = (mi == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 617     rlen = state->strm.avail_in + PPP_HDRLEN + DEFLATE_OVHD;
 618     state->strm.next_out = wptr + 3;
 619     state->strm.avail_out = 1;
 620     decode_proto = 1;
 621
 622     /*
 623      * Call inflate, supplying more input or output as needed.
 624      */
 625     for (;;) {
 626         r = inflate(&state->strm, flush);
 627         if (r != Z_OK) {
 628 #if !DEFLATE_DEBUG
 629             if (state->debug)
 630 #endif
 631                 printf("z_decompress%d: inflate returned %d (%s)\n",
 632                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 633             freemsg(mo_head);
 634             return DECOMP_FATALERROR;
 635         }
 636         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 637             break;              /* all done */
 638         if (state->strm.avail_in == 0 && mi != NULL) {
 639             state->strm.next_in = mi->b_rptr;
 640             state->strm.avail_in = mi->b_wptr - mi->b_rptr;
 641             rlen += state->strm.avail_in;
 642             mi = mi->b_cont;
 643             if (mi == NULL)
 644                 flush = Z_PACKET_FLUSH;
 645         }
 646         if (state->strm.avail_out == 0) {
 647             if (decode_proto) {
 648                 state->strm.avail_out = ospace - PPP_HDRLEN;
 649                 if ((wptr[3] & 1) == 0) {
 650                     /* 2-byte protocol field */
 651                     wptr[2] = wptr[3];
 652                     --state->strm.next_out;
 653                     ++state->strm.avail_out;
 654                 }
 655                 decode_proto = 0;
 656             } else {
 657                 mo->b_wptr += ospace;
 658                 olen += ospace;
 659                 mo->b_cont = allocb(DECOMP_CHUNK, BPRI_MED);
 660                 mo = mo->b_cont;
 661                 if (mo == NULL) {
 662                     freemsg(mo_head);
 663                     return DECOMP_ERROR;
 664                 }
 665                 state->strm.next_out = mo->b_rptr;
 666                 state->strm.avail_out = ospace = DECOMP_CHUNK;
 667             }
 668         }
 669     }
 670     if (decode_proto) {
 671         freemsg(mo_head);
 672         return DECOMP_ERROR;
 673     }
 674     mo->b_wptr += ospace - state->strm.avail_out;
 675     olen += ospace - state->strm.avail_out;
 676
 677 #if DEFLATE_DEBUG
 678     if (olen > state->mru + PPP_HDRLEN)
 679         printf("ppp_deflate%d: exceeded mru (%d > %d)\n",
 680                state->unit, olen, state->mru + PPP_HDRLEN);
 681 #endif
 682
 683     state->stats.unc_bytes += olen;
 684     state->stats.unc_packets++;
 685     state->stats.comp_bytes += rlen;
 686     state->stats.comp_packets++;
 687
 688     *mop = mo_head;
 689     return DECOMP_OK;
 690 }
 691
 692 /*
 693  * Incompressible data has arrived - add it to the history.
 694  */
 695 static void
 696 z_incomp(arg, mi)
 697     void *arg;
 698     mblk_t *mi;
 699 {
 700     struct deflate_state *state = (struct deflate_state *) arg;
 701     u_char *rptr;
 702     int rlen, proto, r;
 703
 704     /*
 705      * Check that the protocol is one we handle.
 706      */
 707     rptr = mi->b_rptr;
 708     if (rptr + PPP_HDRLEN > mi->b_wptr) {
 709         if (!pullupmsg(mi, PPP_HDRLEN))
 710             return;
 711         rptr = mi->b_rptr;
 712     }
 713     proto = PPP_PROTOCOL(rptr);
 714     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
 715         return;
 716
 717     ++state->seqno;
 718
 719     /*
 720      * Iterate through the message blocks, adding the characters in them
 721      * to the decompressor's history.  For the first block, we start
 722      * at the either the 1st or 2nd byte of the protocol field,
 723      * depending on whether the protocol value is compressible.
 724      */
 725     rlen = mi->b_wptr - mi->b_rptr;
 726     state->strm.next_in = rptr + 3;
 727     state->strm.avail_in = rlen - 3;
 728     if (proto > 0xff) {
 729         --state->strm.next_in;
 730         ++state->strm.avail_in;
 731     }
 732     for (;;) {
 733         r = inflateIncomp(&state->strm);
 734         if (r != Z_OK) {
 735             /* gak! */
 736 #if !DEFLATE_DEBUG
 737             if (state->debug)
 738 #endif
 739                 printf("z_incomp%d: inflateIncomp returned %d (%s)\n",
 740                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 741             return;
 742         }
 743         mi = mi->b_cont;
 744         if (mi == NULL)
 745             break;
 746         state->strm.next_in = mi->b_rptr;
 747         state->strm.avail_in = mi->b_wptr - mi->b_rptr;
 748         rlen += state->strm.avail_in;
 749     }
 750
 751     /*
 752      * Update stats.
 753      */
 754     state->stats.inc_bytes += rlen;
 755     state->stats.inc_packets++;
 756     state->stats.unc_bytes += rlen;
 757     state->stats.unc_packets++;
 758 }
 759
 760 #endif /* DO_DEFLATE */