ultrix/ppp-deflate.c

   1 /*      $Id: ppp-deflate.c,v 1.6 2002/12/06 09:49:16 paulus 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 Paul Mackerras. All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  *
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  *
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in
  19  *    the documentation and/or other materials provided with the
  20  *    distribution.
  21  *
  22  * 3. The name(s) of the authors of this software must not be used to
  23  *    endorse or promote products derived from this software without
  24  *    prior written permission.
  25  *
  26  * 4. Redistributions of any form whatsoever must retain the following
  27  *    acknowledgment:
  28  *    "This product includes software developed by Paul Mackerras
  29  *     <paulus@samba.org>".
  30  *
  31  * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
  32  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  33  * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
  34  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  35  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
  36  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
  37  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  38  */
  39
  40 #include "../h/param.h"
  41 #include "../h/types.h"
  42 #include "../h/mbuf.h"
  43 #include "../h/socket.h"
  44 #include "../net/net/if.h"
  45 #include "ppp_defs.h"
  46 #include "zlib.h"
  47
  48 #define PACKETPTR       struct mbuf *
  49 #include "ppp-comp.h"
  50
  51 #if DO_DEFLATE
  52
  53 /*
  54  * State for a Deflate (de)compressor.
  55  */
  56 struct deflate_state {
  57     int         seqno;
  58     int         w_size;
  59     int         unit;
  60     int         hdrlen;
  61     int         mru;
  62     int         debug;
  63     z_stream    strm;
  64     struct compstat stats;
  65 };
  66
  67 #define DEFLATE_OVHD    2               /* Deflate overhead/packet */
  68
  69 static void     *zalloc __P((void *, u_int items, u_int size));
  70 static void     zfree __P((void *, void *ptr));
  71 static void     *z_comp_alloc __P((u_char *options, int opt_len));
  72 static void     *z_decomp_alloc __P((u_char *options, int opt_len));
  73 static void     z_comp_free __P((void *state));
  74 static void     z_decomp_free __P((void *state));
  75 static int      z_comp_init __P((void *state, u_char *options, int opt_len,
  76                                  int unit, int hdrlen, int debug));
  77 static int      z_decomp_init __P((void *state, u_char *options, int opt_len,
  78                                      int unit, int hdrlen, int mru, int debug));
  79 static int      z_compress __P((void *state, struct mbuf **mret,
  80                                   struct mbuf *mp, int slen, int maxolen));
  81 static void     z_incomp __P((void *state, struct mbuf *dmsg));
  82 static int      z_decompress __P((void *state, struct mbuf *cmp,
  83                                     struct mbuf **dmpp));
  84 static void     z_comp_reset __P((void *state));
  85 static void     z_decomp_reset __P((void *state));
  86 static void     z_comp_stats __P((void *state, struct compstat *stats));
  87
  88 /*
  89  * Procedures exported to if_ppp.c.
  90  */
  91 struct compressor ppp_deflate = {
  92     CI_DEFLATE,                 /* compress_proto */
  93     z_comp_alloc,               /* comp_alloc */
  94     z_comp_free,                /* comp_free */
  95     z_comp_init,                /* comp_init */
  96     z_comp_reset,               /* comp_reset */
  97     z_compress,                 /* compress */
  98     z_comp_stats,               /* comp_stat */
  99     z_decomp_alloc,             /* decomp_alloc */
 100     z_decomp_free,              /* decomp_free */
 101     z_decomp_init,              /* decomp_init */
 102     z_decomp_reset,             /* decomp_reset */
 103     z_decompress,               /* decompress */
 104     z_incomp,                   /* incomp */
 105     z_comp_stats,               /* decomp_stat */
 106 };
 107
 108 struct compressor ppp_deflate_draft = {
 109     CI_DEFLATE_DRAFT,           /* compress_proto */
 110     z_comp_alloc,               /* comp_alloc */
 111     z_comp_free,                /* comp_free */
 112     z_comp_init,                /* comp_init */
 113     z_comp_reset,               /* comp_reset */
 114     z_compress,                 /* compress */
 115     z_comp_stats,               /* comp_stat */
 116     z_decomp_alloc,             /* decomp_alloc */
 117     z_decomp_free,              /* decomp_free */
 118     z_decomp_init,              /* decomp_init */
 119     z_decomp_reset,             /* decomp_reset */
 120     z_decompress,               /* decompress */
 121     z_incomp,                   /* incomp */
 122     z_comp_stats,               /* decomp_stat */
 123 };
 124
 125 /*
 126  * Some useful mbuf macros not in mbuf.h.
 127  */
 128 #define M_IS_CLUSTER(m) ((m)->m_off > MMAXOFF)
 129
 130 #define M_TRAILINGSPACE(m) \
 131         ((M_IS_CLUSTER(m) ? (u_int)(m)->m_clptr + M_CLUSTERSZ : MSIZE) \
 132          - ((m)->m_off + (m)->m_len))
 133
 134 /*
 135  * Space allocation and freeing routines for use by zlib routines.
 136  */
 137 void *
 138 zalloc(notused, items, size)
 139     void *notused;
 140     u_int items, size;
 141 {
 142     void *ptr;
 143
 144     KM_ALLOC(ptr, void *, items * size, KM_DEVBUF, KM_NOARG);
 145     return ptr;
 146 }
 147
 148 void
 149 zfree(notused, ptr)
 150     void *notused;
 151     void *ptr;
 152 {
 153     KM_FREE(ptr, KM_DEVBUF);
 154 }
 155
 156 /*
 157  * Allocate space for a compressor.
 158  */
 159 static void *
 160 z_comp_alloc(options, opt_len)
 161     u_char *options;
 162     int opt_len;
 163 {
 164     struct deflate_state *state;
 165     int w_size;
 166
 167     if (opt_len != CILEN_DEFLATE
 168         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 169         || options[1] != CILEN_DEFLATE
 170         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 171         || options[3] != DEFLATE_CHK_SEQUENCE)
 172         return NULL;
 173     w_size = DEFLATE_SIZE(options[2]);
 174     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
 175         return NULL;
 176
 177     KM_ALLOC(state, struct deflate_state *, sizeof(struct deflate_state),
 178              KM_DEVBUF, KM_NOARG);
 179     if (state == NULL)
 180         return NULL;
 181     bzero(state, sizeof(struct deflate_state));
 182
 183     state->strm.next_in = NULL;
 184     state->strm.zalloc = (alloc_func) zalloc;
 185     state->strm.zfree = (free_func) zfree;
 186     if (deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION, DEFLATE_METHOD_VAL,
 187                      -w_size, 8, Z_DEFAULT_STRATEGY) != Z_OK) {
 188         KM_FREE(state, KM_DEVBUF);
 189         return NULL;
 190     }
 191
 192     state->w_size = w_size;
 193     bzero(&state->stats, sizeof(state->stats));
 194     return (void *) state;
 195 }
 196
 197 static void
 198 z_comp_free(arg)
 199     void *arg;
 200 {
 201     struct deflate_state *state = (struct deflate_state *) arg;
 202
 203     deflateEnd(&state->strm);
 204     KM_FREE(state, KM_DEVBUF);
 205 }
 206
 207 static int
 208 z_comp_init(arg, options, opt_len, unit, hdrlen, debug)
 209     void *arg;
 210     u_char *options;
 211     int opt_len, unit, hdrlen, debug;
 212 {
 213     struct deflate_state *state = (struct deflate_state *) arg;
 214
 215     if (opt_len < CILEN_DEFLATE
 216         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 217         || options[1] != CILEN_DEFLATE
 218         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 219         || DEFLATE_SIZE(options[2]) != state->w_size
 220         || options[3] != DEFLATE_CHK_SEQUENCE)
 221         return 0;
 222
 223     state->seqno = 0;
 224     state->unit = unit;
 225     state->hdrlen = hdrlen;
 226     state->debug = debug;
 227
 228     deflateReset(&state->strm);
 229
 230     return 1;
 231 }
 232
 233 static void
 234 z_comp_reset(arg)
 235     void *arg;
 236 {
 237     struct deflate_state *state = (struct deflate_state *) arg;
 238
 239     state->seqno = 0;
 240     deflateReset(&state->strm);
 241 }
 242
 243 int
 244 z_compress(arg, mret, mp, orig_len, maxolen)
 245     void *arg;
 246     struct mbuf **mret;         /* compressed packet (out) */
 247     struct mbuf *mp;            /* uncompressed packet (in) */
 248     int orig_len, maxolen;
 249 {
 250     struct deflate_state *state = (struct deflate_state *) arg;
 251     u_char *rptr, *wptr;
 252     int proto, olen, wspace, r, flush;
 253     struct mbuf *m, *clp;
 254
 255     /*
 256      * Check that the protocol is in the range we handle.
 257      */
 258     rptr = mtod(mp, u_char *);
 259     proto = PPP_PROTOCOL(rptr);
 260     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb) {
 261         *mret = NULL;
 262         return orig_len;
 263     }
 264
 265     /* Allocate one mbuf initially. */
 266     if (maxolen > orig_len)
 267         maxolen = orig_len;
 268     MGET(m, M_DONTWAIT, MT_DATA);
 269     *mret = m;
 270     if (m != NULL) {
 271         if (maxolen + state->hdrlen > MLEN) {
 272             /* MCLGET is not a single statement!!! */
 273             MCLGET(m, clp)
 274         }
 275         m->m_len = 0;
 276         wspace = M_TRAILINGSPACE(m);
 277         if (state->hdrlen > 0 && state->hdrlen + PPP_HDRLEN + 2 < wspace) {
 278             m->m_off += state->hdrlen;
 279             wspace -= state->hdrlen;
 280         }
 281         wptr = mtod(m, u_char *);
 282
 283         /*
 284          * Copy over the PPP header and store the 2-byte sequence number.
 285          */
 286         wptr[0] = PPP_ADDRESS(rptr);
 287         wptr[1] = PPP_CONTROL(rptr);
 288         wptr[2] = PPP_COMP >> 8;
 289         wptr[3] = PPP_COMP;
 290         wptr += PPP_HDRLEN;
 291         wptr[0] = state->seqno >> 8;
 292         wptr[1] = state->seqno;
 293         wptr += 2;
 294         state->strm.next_out = wptr;
 295         state->strm.avail_out = wspace - (PPP_HDRLEN + 2);
 296     } else {
 297         state->strm.next_out = NULL;
 298         state->strm.avail_out = 1000000;
 299         wptr = NULL;
 300         wspace = 0;
 301     }
 302     ++state->seqno;
 303
 304     rptr += (proto > 0xff)? 2: 3;       /* skip 1st proto byte if 0 */
 305     state->strm.next_in = rptr;
 306     state->strm.avail_in = mtod(mp, u_char *) + mp->m_len - rptr;
 307     mp = mp->m_next;
 308     flush = (mp == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 309     olen = 0;
 310     for (;;) {
 311         r = deflate(&state->strm, flush);
 312         if (r != Z_OK) {
 313             printf("z_compress: deflate returned %d (%s)\n",
 314                    r, (state->strm.msg? state->strm.msg: ""));
 315             break;
 316         }
 317         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 318             break;              /* all done */
 319         if (state->strm.avail_in == 0 && mp != NULL) {
 320             state->strm.next_in = mtod(mp, u_char *);
 321             state->strm.avail_in = mp->m_len;
 322             mp = mp->m_next;
 323             if (mp == NULL)
 324                 flush = Z_PACKET_FLUSH;
 325         }
 326         if (state->strm.avail_out == 0) {
 327             if (m != NULL) {
 328                 m->m_len = wspace;
 329                 olen += wspace;
 330                 MGET(m->m_next, M_DONTWAIT, MT_DATA);
 331                 m = m->m_next;
 332                 if (m != NULL) {
 333                     if (maxolen - olen > MLEN) {
 334                         MCLGET(m, clp)
 335                     }
 336                     m->m_len = 0;
 337                     state->strm.next_out = mtod(m, u_char *);
 338                     state->strm.avail_out = wspace = M_TRAILINGSPACE(m);
 339                 }
 340             }
 341             if (m == NULL) {
 342                 state->strm.next_out = NULL;
 343                 state->strm.avail_out = 1000000;
 344             }
 345         }
 346     }
 347     if (m != NULL)
 348         olen += (m->m_len = wspace - state->strm.avail_out);
 349
 350     /*
 351      * See if we managed to reduce the size of the packet.
 352      * If the compressor just gave us a single zero byte, it means
 353      * the packet was incompressible.
 354      */
 355     if (m != NULL && olen < orig_len
 356         && !(olen == PPP_HDRLEN + 3 && *wptr == 0)) {
 357         state->stats.comp_bytes += olen;
 358         state->stats.comp_packets++;
 359     } else {
 360         if (*mret != NULL) {
 361             m_freem(*mret);
 362             *mret = NULL;
 363         }
 364         state->stats.inc_bytes += orig_len;
 365         state->stats.inc_packets++;
 366         olen = orig_len;
 367     }
 368     state->stats.unc_bytes += orig_len;
 369     state->stats.unc_packets++;
 370
 371     return olen;
 372 }
 373
 374 static void
 375 z_comp_stats(arg, stats)
 376     void *arg;
 377     struct compstat *stats;
 378 {
 379     struct deflate_state *state = (struct deflate_state *) arg;
 380     u_int out;
 381
 382     *stats = state->stats;
 383     stats->ratio = stats->unc_bytes;
 384     out = stats->comp_bytes + stats->inc_bytes;
 385     if (stats->ratio <= 0x7ffffff)
 386         stats->ratio <<= 8;
 387     else
 388         out >>= 8;
 389     if (out != 0)
 390         stats->ratio /= out;
 391 }
 392
 393 /*
 394  * Allocate space for a decompressor.
 395  */
 396 static void *
 397 z_decomp_alloc(options, opt_len)
 398     u_char *options;
 399     int opt_len;
 400 {
 401     struct deflate_state *state;
 402     int w_size;
 403
 404     if (opt_len != CILEN_DEFLATE
 405         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 406         || options[1] != CILEN_DEFLATE
 407         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 408         || options[3] != DEFLATE_CHK_SEQUENCE)
 409         return NULL;
 410     w_size = DEFLATE_SIZE(options[2]);
 411     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
 412         return NULL;
 413
 414     KM_ALLOC(state, struct deflate_state *, sizeof(struct deflate_state),
 415              KM_DEVBUF, KM_NOARG);
 416     if (state == NULL)
 417         return NULL;
 418     bzero(state, sizeof(struct deflate_state));
 419
 420     state->strm.next_out = NULL;
 421     state->strm.zalloc = (alloc_func) zalloc;
 422     state->strm.zfree = (free_func) zfree;
 423     if (inflateInit2(&state->strm, -w_size) != Z_OK) {
 424         KM_FREE(state, KM_DEVBUF);
 425         return NULL;
 426     }
 427
 428     state->w_size = w_size;
 429     bzero(&state->stats, sizeof(state->stats));
 430     return (void *) state;
 431 }
 432
 433 static void
 434 z_decomp_free(arg)
 435     void *arg;
 436 {
 437     struct deflate_state *state = (struct deflate_state *) arg;
 438
 439     inflateEnd(&state->strm);
 440     KM_FREE(state, KM_DEVBUF);
 441 }
 442
 443 static int
 444 z_decomp_init(arg, options, opt_len, unit, hdrlen, mru, debug)
 445     void *arg;
 446     u_char *options;
 447     int opt_len, unit, hdrlen, mru, debug;
 448 {
 449     struct deflate_state *state = (struct deflate_state *) arg;
 450
 451     if (opt_len < CILEN_DEFLATE
 452         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 453         || options[1] != CILEN_DEFLATE
 454         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 455         || DEFLATE_SIZE(options[2]) != state->w_size
 456         || options[3] != DEFLATE_CHK_SEQUENCE)
 457         return 0;
 458
 459     state->seqno = 0;
 460     state->unit = unit;
 461     state->hdrlen = hdrlen;
 462     state->debug = debug;
 463     state->mru = mru;
 464
 465     inflateReset(&state->strm);
 466
 467     return 1;
 468 }
 469
 470 static void
 471 z_decomp_reset(arg)
 472     void *arg;
 473 {
 474     struct deflate_state *state = (struct deflate_state *) arg;
 475
 476     state->seqno = 0;
 477     inflateReset(&state->strm);
 478 }
 479
 480 /*
 481  * Decompress a Deflate-compressed packet.
 482  *
 483  * Because of patent problems, we return DECOMP_ERROR for errors
 484  * found by inspecting the input data and for system problems, but
 485  * DECOMP_FATALERROR for any errors which could possibly be said to
 486  * be being detected "after" decompression.  For DECOMP_ERROR,
 487  * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
 488  * infringing a patent of Motorola's if we do, so we take CCP down
 489  * instead.
 490  *
 491  * Given that the frame has the correct sequence number and a good FCS,
 492  * errors such as invalid codes in the input most likely indicate a
 493  * bug, so we return DECOMP_FATALERROR for them in order to turn off
 494  * compression, even though they are detected by inspecting the input.
 495  */
 496 int
 497 z_decompress(arg, mi, mop)
 498     void *arg;
 499     struct mbuf *mi, **mop;
 500 {
 501     struct deflate_state *state = (struct deflate_state *) arg;
 502     struct mbuf *mo, *mo_head, *clp;
 503     u_char *rptr, *wptr;
 504     int rlen, olen, ospace;
 505     int seq, i, flush, r, decode_proto;
 506     u_char hdr[PPP_HDRLEN + DEFLATE_OVHD];
 507
 508     *mop = NULL;
 509     rptr = mtod(mi, u_char *);
 510     rlen = mi->m_len;
 511     for (i = 0; i < PPP_HDRLEN + DEFLATE_OVHD; ++i) {
 512         while (rlen <= 0) {
 513             mi = mi->m_next;
 514             if (mi == NULL)
 515                 return DECOMP_ERROR;
 516             rptr = mtod(mi, u_char *);
 517             rlen = mi->m_len;
 518         }
 519         hdr[i] = *rptr++;
 520         --rlen;
 521     }
 522
 523     /* Check the sequence number. */
 524     seq = (hdr[PPP_HDRLEN] << 8) + hdr[PPP_HDRLEN+1];
 525     if (seq != state->seqno) {
 526         if (state->debug)
 527             printf("z_decompress%d: bad seq # %d, expected %d\n",
 528                    state->unit, seq, state->seqno);
 529         return DECOMP_ERROR;
 530     }
 531     ++state->seqno;
 532
 533     /* Allocate an output mbuf. */
 534     MGET(mo, M_DONTWAIT, MT_DATA);
 535     if (mo == NULL)
 536         return DECOMP_ERROR;
 537     mo_head = mo;
 538     mo->m_next = NULL;
 539     MCLGET(mo, clp)
 540     mo->m_len = 0;
 541     ospace = M_TRAILINGSPACE(mo);
 542     if (state->hdrlen > 0 && state->hdrlen + PPP_HDRLEN < ospace) {
 543         mo->m_off += state->hdrlen;
 544         ospace -= state->hdrlen;
 545     }
 546
 547     /*
 548      * Fill in the first part of the PPP header.  The protocol field
 549      * comes from the decompressed data.
 550      */
 551     wptr = mtod(mo, u_char *);
 552     wptr[0] = PPP_ADDRESS(hdr);
 553     wptr[1] = PPP_CONTROL(hdr);
 554     wptr[2] = 0;
 555
 556     /*
 557      * Set up to call inflate.  We set avail_out to 1 initially so we can
 558      * look at the first byte of the output and decide whether we have
 559      * a 1-byte or 2-byte protocol field.
 560      */
 561     state->strm.next_in = rptr;
 562     state->strm.avail_in = rlen;
 563     mi = mi->m_next;
 564     flush = (mi == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 565     rlen += PPP_HDRLEN + DEFLATE_OVHD;
 566     state->strm.next_out = wptr + 3;
 567     state->strm.avail_out = 1;
 568     decode_proto = 1;
 569     olen = PPP_HDRLEN;
 570
 571     /*
 572      * Call inflate, supplying more input or output as needed.
 573      */
 574     for (;;) {
 575         r = inflate(&state->strm, flush);
 576         if (r != Z_OK) {
 577             if (state->debug)
 578                 printf("z_decompress%d: inflate returned %d (%s)\n",
 579                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 580             m_freem(mo_head);
 581             return DECOMP_FATALERROR;
 582         }
 583         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 584             break;              /* all done */
 585         if (state->strm.avail_in == 0 && mi != NULL) {
 586             state->strm.next_in = mtod(mi, u_char *);
 587             state->strm.avail_in = mi->m_len;
 588             rlen += mi->m_len;
 589             mi = mi->m_next;
 590             if (mi == NULL)
 591                 flush = Z_PACKET_FLUSH;
 592         }
 593         if (state->strm.avail_out == 0) {
 594             if (decode_proto) {
 595                 state->strm.avail_out = ospace - PPP_HDRLEN;
 596                 if ((wptr[3] & 1) == 0) {
 597                     /* 2-byte protocol field */
 598                     wptr[2] = wptr[3];
 599                     --state->strm.next_out;
 600                     ++state->strm.avail_out;
 601                     --olen;
 602                 }
 603                 decode_proto = 0;
 604             } else {
 605                 mo->m_len = ospace;
 606                 olen += ospace;
 607                 MGET(mo->m_next, M_DONTWAIT, MT_DATA);
 608                 mo = mo->m_next;
 609                 if (mo == NULL) {
 610                     m_freem(mo_head);
 611                     return DECOMP_ERROR;
 612                 }
 613                 MCLGET(mo, clp)
 614                 mo->m_len = 0;
 615                 state->strm.next_out = mtod(mo, u_char *);
 616                 state->strm.avail_out = ospace = M_TRAILINGSPACE(mo);
 617             }
 618         }
 619     }
 620     if (decode_proto) {
 621         m_freem(mo_head);
 622         return DECOMP_ERROR;
 623     }
 624     olen += (mo->m_len = ospace - state->strm.avail_out);
 625
 626     state->stats.unc_bytes += olen;
 627     state->stats.unc_packets++;
 628     state->stats.comp_bytes += rlen;
 629     state->stats.comp_packets++;
 630
 631     *mop = mo_head;
 632     return DECOMP_OK;
 633 }
 634
 635 /*
 636  * Incompressible data has arrived - add it to the history.
 637  */
 638 static void
 639 z_incomp(arg, mi)
 640     void *arg;
 641     struct mbuf *mi;
 642 {
 643     struct deflate_state *state = (struct deflate_state *) arg;
 644     u_char *rptr;
 645     int rlen, proto, r;
 646
 647     /*
 648      * Check that the protocol is one we handle.
 649      */
 650     rptr = mtod(mi, u_char *);
 651     proto = PPP_PROTOCOL(rptr);
 652     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
 653         return;
 654
 655     ++state->seqno;
 656
 657     /*
 658      * Iterate through the mbufs, adding the characters in them
 659      * to the decompressor's history.  For the first mbuf, we start
 660      * at the either the 1st or 2nd byte of the protocol field,
 661      * depending on whether the protocol value is compressible.
 662      */
 663     rlen = mi->m_len;
 664     state->strm.next_in = rptr + 3;
 665     state->strm.avail_in = rlen - 3;
 666     if (proto > 0xff) {
 667         --state->strm.next_in;
 668         ++state->strm.avail_in;
 669     }
 670     for (;;) {
 671         r = inflateIncomp(&state->strm);
 672         if (r != Z_OK) {
 673             /* gak! */
 674             if (state->debug) {
 675                 printf("z_incomp%d: inflateIncomp returned %d (%s)\n",
 676                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 677             }
 678             return;
 679         }
 680         mi = mi->m_next;
 681         if (mi == NULL)
 682             break;
 683         state->strm.next_in = mtod(mi, u_char *);
 684         state->strm.avail_in = mi->m_len;
 685         rlen += mi->m_len;
 686     }
 687
 688     /*
 689      * Update stats.
 690      */
 691     state->stats.inc_bytes += rlen;
 692     state->stats.inc_packets++;
 693     state->stats.unc_bytes += rlen;
 694     state->stats.unc_packets++;
 695 }
 696
 697 #endif /* DO_DEFLATE */