bsd/net/ppp_deflate.c

   1 /*
   2  * Copyright (c) 2000-2010 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * ppp_deflate.c - interface the zlib procedures for Deflate compression
  30  * and decompression (as used by gzip) to the PPP code.
  31  * This version is for use with mbufs on BSD-derived systems.
  32  *
  33  * Copyright (c) 1994 The Australian National University.
  34  * All rights reserved.
  35  *
  36  * Permission to use, copy, modify, and distribute this software and its
  37  * documentation is hereby granted, provided that the above copyright
  38  * notice appears in all copies.  This software is provided without any
  39  * warranty, express or implied. The Australian National University
  40  * makes no representations about the suitability of this software for
  41  * any purpose.
  42  *
  43  * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
  44  * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  45  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
  46  * THE AUSTRALIAN NATIONAL UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY
  47  * OF SUCH DAMAGE.
  48  *
  49  * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
  50  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  51  * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  52  * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
  53  * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
  54  * OR MODIFICATIONS.
  55  */
  56 /*
  57  * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
  58  * support for mandatory and extensible security protections.  This notice
  59  * is included in support of clause 2.2 (b) of the Apple Public License,
  60  * Version 2.0.
  61  */
  62
  63 #include <sys/param.h>
  64 #include <sys/systm.h>
  65 #include <sys/malloc.h>
  66 #include <sys/mbuf.h>
  67 #include <net/ppp_defs.h>
  68 #include <libkern/zlib.h>
  69
  70 #define PACKETPTR       struct mbuf *
  71 #include <net/ppp_comp.h>
  72
  73 #if CONFIG_MACF_NET
  74 #include <security/mac_framework.h>
  75 #endif
  76
  77 #if DO_DEFLATE
  78
  79 #define DEFLATE_DEBUG   1
  80
  81 /*
  82  * State for a Deflate (de)compressor.
  83  */
  84 struct deflate_state {
  85     int         seqno;
  86     int         w_size;
  87     int         unit;
  88     int         hdrlen;
  89     int         mru;
  90     int         debug;
  91     z_stream    strm;
  92     struct compstat stats;
  93 };
  94
  95 #define DEFLATE_OVHD    2               /* Deflate overhead/packet */
  96
  97 static void     *z_alloc(void *, u_int items, u_int size);
  98 static void     z_free(void *, void *ptr);
  99 static void     *z_comp_alloc(u_char *options, int opt_len);
 100 static void     *z_decomp_alloc(u_char *options, int opt_len);
 101 static void     z_comp_free(void *state);
 102 static void     z_decomp_free(void *state);
 103 static int      z_comp_init(void *state, u_char *options, int opt_len,
 104                                  int unit, int hdrlen, int debug);
 105 static int      z_decomp_init(void *state, u_char *options, int opt_len,
 106                                      int unit, int hdrlen, int mru, int debug);
 107 static int      z_compress(void *state, struct mbuf **mret,
 108                                   struct mbuf *mp, int slen, int maxolen);
 109 static void     z_incomp(void *state, struct mbuf *dmsg);
 110 static int      z_decompress(void *state, struct mbuf *cmp, struct mbuf **dmpp);
 111 static void     z_comp_reset(void *state);
 112 static void     z_decomp_reset(void *state);
 113 static void     z_comp_stats(void *state, struct compstat *stats);
 114
 115 /*
 116  * Procedures exported to if_ppp.c.
 117  */
 118 struct compressor ppp_deflate = {
 119     CI_DEFLATE,                 /* compress_proto */
 120     z_comp_alloc,               /* comp_alloc */
 121     z_comp_free,                /* comp_free */
 122     z_comp_init,                /* comp_init */
 123     z_comp_reset,               /* comp_reset */
 124     z_compress,                 /* compress */
 125     z_comp_stats,               /* comp_stat */
 126     z_decomp_alloc,             /* decomp_alloc */
 127     z_decomp_free,              /* decomp_free */
 128     z_decomp_init,              /* decomp_init */
 129     z_decomp_reset,             /* decomp_reset */
 130     z_decompress,               /* decompress */
 131     z_incomp,                   /* incomp */
 132     z_comp_stats,               /* decomp_stat */
 133 };
 134
 135 struct compressor ppp_deflate_draft = {
 136     CI_DEFLATE_DRAFT,           /* compress_proto */
 137     z_comp_alloc,               /* comp_alloc */
 138     z_comp_free,                /* comp_free */
 139     z_comp_init,                /* comp_init */
 140     z_comp_reset,               /* comp_reset */
 141     z_compress,                 /* compress */
 142     z_comp_stats,               /* comp_stat */
 143     z_decomp_alloc,             /* decomp_alloc */
 144     z_decomp_free,              /* decomp_free */
 145     z_decomp_init,              /* decomp_init */
 146     z_decomp_reset,             /* decomp_reset */
 147     z_decompress,               /* decompress */
 148     z_incomp,                   /* incomp */
 149     z_comp_stats,               /* decomp_stat */
 150 };
 151
 152 /*
 153  * Space allocation and freeing routines for use by zlib routines.
 154  */
 155 void *
 156 z_alloc(notused, items, size)
 157     void *notused;
 158     u_int items, size;
 159 {
 160     void *ptr;
 161
 162     MALLOC(ptr, void *, items * size, M_DEVBUF, M_NOWAIT);
 163     return ptr;
 164 }
 165
 166 void
 167 z_free(notused, ptr)
 168     void *notused;
 169     void *ptr;
 170 {
 171     FREE(ptr, M_DEVBUF);
 172 }
 173
 174 /*
 175  * Allocate space for a compressor.
 176  */
 177 static void *
 178 z_comp_alloc(options, opt_len)
 179     u_char *options;
 180     int opt_len;
 181 {
 182     struct deflate_state *state;
 183     int w_size;
 184
 185     if (opt_len != CILEN_DEFLATE
 186         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 187         || options[1] != CILEN_DEFLATE
 188         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 189         || options[3] != DEFLATE_CHK_SEQUENCE)
 190         return NULL;
 191     w_size = DEFLATE_SIZE(options[2]);
 192     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
 193         return NULL;
 194
 195     MALLOC(state, struct deflate_state *, sizeof(struct deflate_state),
 196            M_DEVBUF, M_NOWAIT);
 197     if (state == NULL)
 198         return NULL;
 199
 200     state->strm.next_in = NULL;
 201     state->strm.zalloc = z_alloc;
 202     state->strm.zfree = z_free;
 203     if (deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION, DEFLATE_METHOD_VAL,
 204                      -w_size, 8, Z_DEFAULT_STRATEGY) != Z_OK) {
 205         FREE(state, M_DEVBUF);
 206         return NULL;
 207     }
 208
 209     state->w_size = w_size;
 210     bzero(&state->stats, sizeof(state->stats));
 211     return (void *) state;
 212 }
 213
 214 static void
 215 z_comp_free(arg)
 216     void *arg;
 217 {
 218     struct deflate_state *state = (struct deflate_state *) arg;
 219
 220     deflateEnd(&state->strm);
 221     FREE(state, M_DEVBUF);
 222 }
 223
 224 static int
 225 z_comp_init(arg, options, opt_len, unit, hdrlen, debug)
 226     void *arg;
 227     u_char *options;
 228     int opt_len, unit, hdrlen, debug;
 229 {
 230     struct deflate_state *state = (struct deflate_state *) arg;
 231
 232     if (opt_len < CILEN_DEFLATE
 233         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 234         || options[1] != CILEN_DEFLATE
 235         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 236         || DEFLATE_SIZE(options[2]) != state->w_size
 237         || options[3] != DEFLATE_CHK_SEQUENCE)
 238         return 0;
 239
 240     state->seqno = 0;
 241     state->unit = unit;
 242     state->hdrlen = hdrlen;
 243     state->debug = debug;
 244
 245     deflateReset(&state->strm);
 246
 247     return 1;
 248 }
 249
 250 static void
 251 z_comp_reset(arg)
 252     void *arg;
 253 {
 254     struct deflate_state *state = (struct deflate_state *) arg;
 255
 256     state->seqno = 0;
 257     deflateReset(&state->strm);
 258 }
 259
 260 int
 261 z_compress(arg, mret, mp, orig_len, maxolen)
 262     void *arg;
 263     struct mbuf **mret;         /* compressed packet (out) */
 264     struct mbuf *mp;            /* uncompressed packet (in) */
 265     int orig_len, maxolen;
 266 {
 267     struct deflate_state *state = (struct deflate_state *) arg;
 268     u_char *rptr, *wptr;
 269     int proto, olen, wspace, r, flush;
 270     struct mbuf *m;
 271
 272     /*
 273      * Check that the protocol is in the range we handle.
 274      */
 275     rptr = mtod(mp, u_char *);
 276     proto = PPP_PROTOCOL(rptr);
 277     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb) {
 278         *mret = NULL;
 279         return orig_len;
 280     }
 281
 282     /* Allocate one mbuf initially. */
 283     if (maxolen > orig_len)
 284         maxolen = orig_len;
 285     MGET(m, M_DONTWAIT, MT_DATA);
 286     *mret = m;
 287     if (m != NULL) {
 288         m->m_len = 0;
 289         if (maxolen + state->hdrlen > MLEN)
 290             MCLGET(m, M_DONTWAIT);
 291         wspace = M_TRAILINGSPACE(m);
 292         if (state->hdrlen + PPP_HDRLEN + 2 < wspace) {
 293             m->m_data += state->hdrlen;
 294             wspace -= state->hdrlen;
 295         }
 296         wptr = mtod(m, u_char *);
 297
 298         /*
 299          * Copy over the PPP header and store the 2-byte sequence number.
 300          */
 301         wptr[0] = PPP_ADDRESS(rptr);
 302         wptr[1] = PPP_CONTROL(rptr);
 303         wptr[2] = PPP_COMP >> 8;
 304         wptr[3] = PPP_COMP;
 305         wptr += PPP_HDRLEN;
 306         wptr[0] = state->seqno >> 8;
 307         wptr[1] = state->seqno;
 308         wptr += 2;
 309         state->strm.next_out = wptr;
 310         state->strm.avail_out = wspace - (PPP_HDRLEN + 2);
 311     } else {
 312         state->strm.next_out = NULL;
 313         state->strm.avail_out = 1000000;
 314         wptr = NULL;
 315         wspace = 0;
 316     }
 317     ++state->seqno;
 318
 319     rptr += (proto > 0xff)? 2: 3;       /* skip 1st proto byte if  0 */
 320     state->strm.next_in = rptr;
 321     state->strm.avail_in = mtod(mp, u_char *) + mp->m_len - rptr;
 322     mp = mp->m_next;
 323     flush = (mp == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 324     olen = 0;
 325     for (;;) {
 326         r = deflate(&state->strm, flush);
 327         if (r != Z_OK) {
 328             printf("z_compress: deflate returned %d (%s)\n",
 329                    r, (state->strm.msg? state->strm.msg: ""));
 330             break;
 331         }
 332         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 333             break;              /* all done */
 334         if (state->strm.avail_in == 0 && mp != NULL) {
 335             state->strm.next_in = mtod(mp, u_char *);
 336             state->strm.avail_in = mp->m_len;
 337             mp = mp->m_next;
 338             if (mp == NULL)
 339                 flush = Z_PACKET_FLUSH;
 340         }
 341         if (state->strm.avail_out == 0) {
 342             if (m != NULL) {
 343                 m->m_len = wspace;
 344                 olen += wspace;
 345                 MGET(m->m_next, M_DONTWAIT, MT_DATA);
 346                 m = m->m_next;
 347                 if (m != NULL) {
 348                     m->m_len = 0;
 349                     if (maxolen - olen > MLEN)
 350                         MCLGET(m, M_DONTWAIT);
 351                     state->strm.next_out = mtod(m, u_char *);
 352                     state->strm.avail_out = wspace = M_TRAILINGSPACE(m);
 353                 }
 354             }
 355             if (m == NULL) {
 356                 state->strm.next_out = NULL;
 357                 state->strm.avail_out = 1000000;
 358             }
 359         }
 360     }
 361     if (m != NULL)
 362         olen += (m->m_len = wspace - state->strm.avail_out);
 363
 364     /*
 365      * See if we managed to reduce the size of the packet.
 366      */
 367     if (m != NULL && olen < orig_len) {
 368         state->stats.comp_bytes += olen;
 369         state->stats.comp_packets++;
 370     } else {
 371         if (*mret != NULL) {
 372             m_freem(*mret);
 373             *mret = NULL;
 374         }
 375         state->stats.inc_bytes += orig_len;
 376         state->stats.inc_packets++;
 377         olen = orig_len;
 378     }
 379     state->stats.unc_bytes += orig_len;
 380     state->stats.unc_packets++;
 381
 382     return olen;
 383 }
 384
 385 static void
 386 z_comp_stats(arg, stats)
 387     void *arg;
 388     struct compstat *stats;
 389 {
 390     struct deflate_state *state = (struct deflate_state *) arg;
 391     u_int out;
 392
 393     *stats = state->stats;
 394     stats->ratio = stats->unc_bytes;
 395     out = stats->comp_bytes + stats->inc_bytes;
 396     if (stats->ratio <= 0x7ffffff)
 397         stats->ratio <<= 8;
 398     else
 399         out >>= 8;
 400     if (out != 0)
 401         stats->ratio /= out;
 402 }
 403
 404 /*
 405  * Allocate space for a decompressor.
 406  */
 407 static void *
 408 z_decomp_alloc(options, opt_len)
 409     u_char *options;
 410     int opt_len;
 411 {
 412     struct deflate_state *state;
 413     int w_size;
 414
 415     if (opt_len != CILEN_DEFLATE
 416         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 417         || options[1] != CILEN_DEFLATE
 418         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 419         || options[3] != DEFLATE_CHK_SEQUENCE)
 420         return NULL;
 421     w_size = DEFLATE_SIZE(options[2]);
 422     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
 423         return NULL;
 424
 425     MALLOC(state, struct deflate_state *, sizeof(struct deflate_state),
 426            M_DEVBUF, M_NOWAIT);
 427     if (state == NULL)
 428         return NULL;
 429
 430     state->strm.next_out = NULL;
 431     state->strm.zalloc = z_alloc;
 432     state->strm.zfree = z_free;
 433     if (inflateInit2(&state->strm, -w_size) != Z_OK) {
 434         FREE(state, M_DEVBUF);
 435         return NULL;
 436     }
 437
 438     state->w_size = w_size;
 439     bzero(&state->stats, sizeof(state->stats));
 440     return (void *) state;
 441 }
 442
 443 static void
 444 z_decomp_free(arg)
 445     void *arg;
 446 {
 447     struct deflate_state *state = (struct deflate_state *) arg;
 448
 449     inflateEnd(&state->strm);
 450     FREE(state, M_DEVBUF);
 451 }
 452
 453 static int
 454 z_decomp_init(arg, options, opt_len, unit, hdrlen, mru, debug)
 455     void *arg;
 456     u_char *options;
 457     int opt_len, unit, hdrlen, mru, debug;
 458 {
 459     struct deflate_state *state = (struct deflate_state *) arg;
 460
 461     if (opt_len < CILEN_DEFLATE
 462         || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
 463         || options[1] != CILEN_DEFLATE
 464         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 465         || DEFLATE_SIZE(options[2]) != state->w_size
 466         || options[3] != DEFLATE_CHK_SEQUENCE)
 467         return 0;
 468
 469     state->seqno = 0;
 470     state->unit = unit;
 471     state->hdrlen = hdrlen;
 472     state->debug = debug;
 473     state->mru = mru;
 474
 475     inflateReset(&state->strm);
 476
 477     return 1;
 478 }
 479
 480 static void
 481 z_decomp_reset(arg)
 482     void *arg;
 483 {
 484     struct deflate_state *state = (struct deflate_state *) arg;
 485
 486     state->seqno = 0;
 487     inflateReset(&state->strm);
 488 }
 489
 490 /*
 491  * Decompress a Deflate-compressed packet.
 492  *
 493  * Because of patent problems, we return DECOMP_ERROR for errors
 494  * found by inspecting the input data and for system problems, but
 495  * DECOMP_FATALERROR for any errors which could possibly be said to
 496  * be being detected "after" decompression.  For DECOMP_ERROR,
 497  * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
 498  * infringing a patent of Motorola's if we do, so we take CCP down
 499  * instead.
 500  *
 501  * Given that the frame has the correct sequence number and a good FCS,
 502  * errors such as invalid codes in the input most likely indicate a
 503  * bug, so we return DECOMP_FATALERROR for them in order to turn off
 504  * compression, even though they are detected by inspecting the input.
 505  */
 506 int
 507 z_decompress(arg, mi, mop)
 508     void *arg;
 509     struct mbuf *mi, **mop;
 510 {
 511     struct deflate_state *state = (struct deflate_state *) arg;
 512     struct mbuf *mo, *mo_head;
 513     u_char *rptr, *wptr;
 514     int rlen, olen, ospace;
 515     int seq, i, flush, r, decode_proto;
 516     u_char hdr[PPP_HDRLEN + DEFLATE_OVHD];
 517
 518     *mop = NULL;
 519     rptr = mtod(mi, u_char *);
 520     rlen = mi->m_len;
 521     for (i = 0; i < PPP_HDRLEN + DEFLATE_OVHD; ++i) {
 522         while (rlen <= 0) {
 523             mi = mi->m_next;
 524             if (mi == NULL)
 525                 return DECOMP_ERROR;
 526             rptr = mtod(mi, u_char *);
 527             rlen = mi->m_len;
 528         }
 529         hdr[i] = *rptr++;
 530         --rlen;
 531     }
 532
 533     /* Check the sequence number. */
 534     seq = (hdr[PPP_HDRLEN] << 8) + hdr[PPP_HDRLEN+1];
 535     if (seq != state->seqno) {
 536         if (state->debug)
 537             printf("z_decompress%d: bad seq # %d, expected %d\n",
 538                    state->unit, seq, state->seqno);
 539         return DECOMP_ERROR;
 540     }
 541     ++state->seqno;
 542
 543     /* Allocate an output mbuf. */
 544     MGETHDR(mo, M_DONTWAIT, MT_DATA);
 545     if (mo == NULL)
 546         return DECOMP_ERROR;
 547     mo_head = mo;
 548     mo->m_len = 0;
 549     mo->m_next = NULL;
 550     MCLGET(mo, M_DONTWAIT);
 551     ospace = M_TRAILINGSPACE(mo);
 552     if (state->hdrlen + PPP_HDRLEN < ospace) {
 553         mo->m_data += state->hdrlen;
 554         ospace -= state->hdrlen;
 555     }
 556 #if CONFIG_MACF_NET
 557    mac_mbuf_label_copy(mi, mo);
 558 #endif
 559
 560     /*
 561      * Fill in the first part of the PPP header.  The protocol field
 562      * comes from the decompressed data.
 563      */
 564     wptr = mtod(mo, u_char *);
 565     wptr[0] = PPP_ADDRESS(hdr);
 566     wptr[1] = PPP_CONTROL(hdr);
 567     wptr[2] = 0;
 568
 569     /*
 570      * Set up to call inflate.  We set avail_out to 1 initially so we can
 571      * look at the first byte of the output and decide whether we have
 572      * a 1-byte or 2-byte protocol field.
 573      */
 574     state->strm.next_in = rptr;
 575     state->strm.avail_in = rlen;
 576     mi = mi->m_next;
 577     flush = (mi == NULL)? Z_PACKET_FLUSH: Z_NO_FLUSH;
 578     rlen += PPP_HDRLEN + DEFLATE_OVHD;
 579     state->strm.next_out = wptr + 3;
 580     state->strm.avail_out = 1;
 581     decode_proto = 1;
 582     olen = PPP_HDRLEN;
 583
 584     /*
 585      * Call inflate, supplying more input or output as needed.
 586      */
 587     for (;;) {
 588         r = inflate(&state->strm, flush);
 589         if (r != Z_OK) {
 590 #if !DEFLATE_DEBUG
 591             if (state->debug)
 592 #endif
 593                 printf("z_decompress%d: inflate returned %d (%s)\n",
 594                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 595             m_freem(mo_head);
 596             return DECOMP_FATALERROR;
 597         }
 598         if (flush != Z_NO_FLUSH && state->strm.avail_out != 0)
 599             break;              /* all done */
 600         if (state->strm.avail_in == 0 && mi != NULL) {
 601             state->strm.next_in = mtod(mi, u_char *);
 602             state->strm.avail_in = mi->m_len;
 603             rlen += mi->m_len;
 604             mi = mi->m_next;
 605             if (mi == NULL)
 606                 flush = Z_PACKET_FLUSH;
 607         }
 608         if (state->strm.avail_out == 0) {
 609             if (decode_proto) {
 610                 state->strm.avail_out = ospace - PPP_HDRLEN;
 611                 if ((wptr[3] & 1) == 0) {
 612                     /* 2-byte protocol field */
 613                     wptr[2] = wptr[3];
 614                     --state->strm.next_out;
 615                     ++state->strm.avail_out;
 616                     --olen;
 617                 }
 618                 decode_proto = 0;
 619             } else {
 620                 mo->m_len = ospace;
 621                 olen += ospace;
 622                 MGET(mo->m_next, M_DONTWAIT, MT_DATA);
 623                 mo = mo->m_next;
 624                 if (mo == NULL) {
 625                     m_freem(mo_head);
 626                     return DECOMP_ERROR;
 627                 }
 628                 MCLGET(mo, M_DONTWAIT);
 629                 state->strm.next_out = mtod(mo, u_char *);
 630                 state->strm.avail_out = ospace = M_TRAILINGSPACE(mo);
 631             }
 632         }
 633     }
 634     if (decode_proto) {
 635         m_freem(mo_head);
 636         return DECOMP_ERROR;
 637     }
 638     olen += (mo->m_len = ospace - state->strm.avail_out);
 639 #if DEFLATE_DEBUG
 640     if (state->debug && olen > state->mru + PPP_HDRLEN)
 641         printf("ppp_deflate%d: exceeded mru (%d > %d)\n",
 642                state->unit, olen, state->mru + PPP_HDRLEN);
 643 #endif
 644
 645     state->stats.unc_bytes += olen;
 646     state->stats.unc_packets++;
 647     state->stats.comp_bytes += rlen;
 648     state->stats.comp_packets++;
 649
 650     *mop = mo_head;
 651     return DECOMP_OK;
 652 }
 653
 654 /*
 655  * Incompressible data has arrived - add it to the history.
 656  */
 657 static void
 658 z_incomp(arg, mi)
 659     void *arg;
 660     struct mbuf *mi;
 661 {
 662     struct deflate_state *state = (struct deflate_state *) arg;
 663     u_char *rptr;
 664     int rlen, proto, r;
 665
 666     /*
 667      * Check that the protocol is one we handle.
 668      */
 669     rptr = mtod(mi, u_char *);
 670     proto = PPP_PROTOCOL(rptr);
 671     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
 672         return;
 673
 674     ++state->seqno;
 675
 676     /*
 677      * Iterate through the mbufs, adding the characters in them
 678      * to the decompressor's history.  For the first mbuf, we start
 679      * at the either the 1st or 2nd byte of the protocol field,
 680      * depending on whether the protocol value is compressible.
 681      */
 682     rlen = mi->m_len;
 683     state->strm.next_in = rptr + 3;
 684     state->strm.avail_in = rlen - 3;
 685     if (proto > 0xff) {
 686         --state->strm.next_in;
 687         ++state->strm.avail_in;
 688     }
 689     for (;;) {
 690         r = inflateIncomp(&state->strm);
 691         if (r != Z_OK) {
 692             /* gak! */
 693 #if !DEFLATE_DEBUG
 694             if (state->debug)
 695 #endif
 696                 printf("z_incomp%d: inflateIncomp returned %d (%s)\n",
 697                        state->unit, r, (state->strm.msg? state->strm.msg: ""));
 698             return;
 699         }
 700         mi = mi->m_next;
 701         if (mi == NULL)
 702             break;
 703         state->strm.next_in = mtod(mi, u_char *);
 704         state->strm.avail_in = mi->m_len;
 705         rlen += mi->m_len;
 706     }
 707
 708     /*
 709      * Update stats.
 710      */
 711     state->stats.inc_bytes += rlen;
 712     state->stats.inc_packets++;
 713     state->stats.unc_bytes += rlen;
 714     state->stats.unc_packets++;
 715 }
 716
 717 #endif /* DO_DEFLATE */