pppdump/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  *
   5  * Copyright (c) 1994 The Australian National University.
   6  * All rights reserved.
   7  *
   8  * Permission to use, copy, modify, and distribute this software and its
   9  * documentation is hereby granted, provided that the above copyright
  10  * notice appears in all copies.  This software is provided without any
  11  * warranty, express or implied. The Australian National University
  12  * makes no representations about the suitability of this software for
  13  * any purpose.
  14  *
  15  * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
  16  * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  17  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
  18  * THE AUSTRALIAN NATIONAL UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY
  19  * OF SUCH DAMAGE.
  20  *
  21  * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
  22  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  23  * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  24  * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
  25  * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
  26  * OR MODIFICATIONS.
  27  *
  28  * $Id: deflate.c,v 1.3 1999/04/16 11:35:59 paulus Exp $
  29  */
  30
  31 #include <sys/types.h>
  32 #include <stddef.h>
  33 #include <stdlib.h>
  34 #include "ppp_defs.h"
  35 #include "ppp-comp.h"
  36 #include "zlib.h"
  37
  38 #if DO_DEFLATE
  39
  40 #define DEFLATE_DEBUG   1
  41
  42 /*
  43  * State for a Deflate (de)compressor.
  44  */
  45 struct deflate_state {
  46     int         seqno;
  47     int         w_size;
  48     int         unit;
  49     int         hdrlen;
  50     int         mru;
  51     int         debug;
  52     z_stream    strm;
  53     struct compstat stats;
  54 };
  55
  56 #define DEFLATE_OVHD    2               /* Deflate overhead/packet */
  57
  58 static void     *z_alloc __P((void *, u_int items, u_int size));
  59 static void     z_free __P((void *, void *ptr, u_int nb));
  60 static void     *z_decomp_alloc __P((u_char *options, int opt_len));
  61 static void     z_decomp_free __P((void *state));
  62 static int      z_decomp_init __P((void *state, u_char *options, int opt_len,
  63                                      int unit, int hdrlen, int mru, int debug));
  64 static void     z_incomp __P((void *state, u_char *dmsg, int len));
  65 static int      z_decompress __P((void *state, u_char *cmp, int inlen,
  66                                     u_char *dmp, int *outlenp));
  67 static void     z_decomp_reset __P((void *state));
  68 static void     z_comp_stats __P((void *state, struct compstat *stats));
  69
  70 /*
  71  * Procedures exported to if_ppp.c.
  72  */
  73 struct compressor ppp_deflate = {
  74     CI_DEFLATE,                 /* compress_proto */
  75     z_decomp_alloc,             /* decomp_alloc */
  76     z_decomp_free,              /* decomp_free */
  77     z_decomp_init,              /* decomp_init */
  78     z_decomp_reset,             /* decomp_reset */
  79     z_decompress,               /* decompress */
  80     z_incomp,                   /* incomp */
  81     z_comp_stats,               /* decomp_stat */
  82 };
  83
  84 /*
  85  * Space allocation and freeing routines for use by zlib routines.
  86  */
  87 static void *
  88 z_alloc(notused, items, size)
  89     void *notused;
  90     u_int items, size;
  91 {
  92     return malloc(items * size);
  93 }
  94
  95 static void
  96 z_free(notused, ptr, nbytes)
  97     void *notused;
  98     void *ptr;
  99     u_int nbytes;
 100 {
 101     free(ptr);
 102 }
 103
 104 static void
 105 z_comp_stats(arg, stats)
 106     void *arg;
 107     struct compstat *stats;
 108 {
 109     struct deflate_state *state = (struct deflate_state *) arg;
 110     u_int out;
 111
 112     *stats = state->stats;
 113     stats->ratio = stats->unc_bytes;
 114     out = stats->comp_bytes + stats->unc_bytes;
 115     if (stats->ratio <= 0x7ffffff)
 116         stats->ratio <<= 8;
 117     else
 118         out >>= 8;
 119     if (out != 0)
 120         stats->ratio /= out;
 121 }
 122
 123 /*
 124  * Allocate space for a decompressor.
 125  */
 126 static void *
 127 z_decomp_alloc(options, opt_len)
 128     u_char *options;
 129     int opt_len;
 130 {
 131     struct deflate_state *state;
 132     int w_size;
 133
 134     if (opt_len != CILEN_DEFLATE || options[0] != CI_DEFLATE
 135         || options[1] != CILEN_DEFLATE
 136         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 137         || options[3] != DEFLATE_CHK_SEQUENCE)
 138         return NULL;
 139     w_size = DEFLATE_SIZE(options[2]);
 140     if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
 141         return NULL;
 142
 143     state = (struct deflate_state *) malloc(sizeof(*state));
 144     if (state == NULL)
 145         return NULL;
 146
 147     state->strm.next_out = NULL;
 148     state->strm.zalloc = (alloc_func) z_alloc;
 149     state->strm.zfree = (free_func) z_free;
 150     if (inflateInit2(&state->strm, -w_size) != Z_OK) {
 151         free(state);
 152         return NULL;
 153     }
 154
 155     state->w_size = w_size;
 156     memset(&state->stats, 0, sizeof(state->stats));
 157     return (void *) state;
 158 }
 159
 160 static void
 161 z_decomp_free(arg)
 162     void *arg;
 163 {
 164     struct deflate_state *state = (struct deflate_state *) arg;
 165
 166     inflateEnd(&state->strm);
 167     free(state);
 168 }
 169
 170 static int
 171 z_decomp_init(arg, options, opt_len, unit, hdrlen, mru, debug)
 172     void *arg;
 173     u_char *options;
 174     int opt_len, unit, hdrlen, mru, debug;
 175 {
 176     struct deflate_state *state = (struct deflate_state *) arg;
 177
 178     if (opt_len < CILEN_DEFLATE || options[0] != CI_DEFLATE
 179         || options[1] != CILEN_DEFLATE
 180         || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
 181         || DEFLATE_SIZE(options[2]) != state->w_size
 182         || options[3] != DEFLATE_CHK_SEQUENCE)
 183         return 0;
 184
 185     state->seqno = 0;
 186     state->unit = unit;
 187     state->hdrlen = hdrlen;
 188     state->debug = debug;
 189     state->mru = mru;
 190
 191     inflateReset(&state->strm);
 192
 193     return 1;
 194 }
 195
 196 static void
 197 z_decomp_reset(arg)
 198     void *arg;
 199 {
 200     struct deflate_state *state = (struct deflate_state *) arg;
 201
 202     state->seqno = 0;
 203     inflateReset(&state->strm);
 204 }
 205
 206 /*
 207  * Decompress a Deflate-compressed packet.
 208  *
 209  * Because of patent problems, we return DECOMP_ERROR for errors
 210  * found by inspecting the input data and for system problems, but
 211  * DECOMP_FATALERROR for any errors which could possibly be said to
 212  * be being detected "after" decompression.  For DECOMP_ERROR,
 213  * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
 214  * infringing a patent of Motorola's if we do, so we take CCP down
 215  * instead.
 216  *
 217  * Given that the frame has the correct sequence number and a good FCS,
 218  * errors such as invalid codes in the input most likely indicate a
 219  * bug, so we return DECOMP_FATALERROR for them in order to turn off
 220  * compression, even though they are detected by inspecting the input.
 221  */
 222 static int
 223 z_decompress(arg, mi, inlen, mo, outlenp)
 224     void *arg;
 225     u_char *mi, *mo;
 226     int inlen, *outlenp;
 227 {
 228     struct deflate_state *state = (struct deflate_state *) arg;
 229     u_char *rptr, *wptr;
 230     int rlen, olen, ospace;
 231     int seq, i, flush, r, decode_proto;
 232
 233     rptr = mi;
 234     if (*rptr == 0)
 235         ++rptr;
 236     ++rptr;
 237
 238     /* Check the sequence number. */
 239     seq = (rptr[0] << 8) + rptr[1];
 240     rptr += 2;
 241     if (seq != state->seqno) {
 242 #if !DEFLATE_DEBUG
 243         if (state->debug)
 244 #endif
 245             printf("z_decompress%d: bad seq # %d, expected %d\n",
 246                    state->unit, seq, state->seqno);
 247         return DECOMP_ERROR;
 248     }
 249     ++state->seqno;
 250
 251     /*
 252      * Set up to call inflate.
 253      */
 254     wptr = mo;
 255     state->strm.next_in = rptr;
 256     state->strm.avail_in = mi + inlen - rptr;
 257     rlen = state->strm.avail_in + PPP_HDRLEN + DEFLATE_OVHD;
 258     state->strm.next_out = wptr;
 259     state->strm.avail_out = state->mru + 2;
 260
 261     r = inflate(&state->strm, Z_PACKET_FLUSH);
 262     if (r != Z_OK) {
 263 #if !DEFLATE_DEBUG
 264         if (state->debug)
 265 #endif
 266             printf("z_decompress%d: inflate returned %d (%s)\n",
 267                    state->unit, r, (state->strm.msg? state->strm.msg: ""));
 268         return DECOMP_FATALERROR;
 269     }
 270     olen = state->mru + 2 - state->strm.avail_out;
 271     *outlenp = olen;
 272
 273     if ((wptr[0] & 1) != 0)
 274         ++olen;                 /* for suppressed protocol high byte */
 275     olen += 2;                  /* for address, control */
 276
 277 #if DEFLATE_DEBUG
 278     if (olen > state->mru + PPP_HDRLEN)
 279         printf("ppp_deflate%d: exceeded mru (%d > %d)\n",
 280                state->unit, olen, state->mru + PPP_HDRLEN);
 281 #endif
 282
 283     state->stats.unc_bytes += olen;
 284     state->stats.unc_packets++;
 285     state->stats.comp_bytes += rlen;
 286     state->stats.comp_packets++;
 287
 288     return DECOMP_OK;
 289 }
 290
 291 /*
 292  * Incompressible data has arrived - add it to the history.
 293  */
 294 static void
 295 z_incomp(arg, mi, mlen)
 296     void *arg;
 297     u_char *mi;
 298     int mlen;
 299 {
 300     struct deflate_state *state = (struct deflate_state *) arg;
 301     u_char *rptr;
 302     int rlen, proto, r;
 303
 304     /*
 305      * Check that the protocol is one we handle.
 306      */
 307     rptr = mi;
 308     proto = rptr[0];
 309     if ((proto & 1) == 0)
 310         proto = (proto << 8) + rptr[1];
 311     if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
 312         return;
 313
 314     ++state->seqno;
 315
 316     if (rptr[0] == 0)
 317         ++rptr;
 318     rlen = mi + mlen - rptr;
 319     state->strm.next_in = rptr;
 320     state->strm.avail_in = rlen;
 321     r = inflateIncomp(&state->strm);
 322     if (r != Z_OK) {
 323         /* gak! */
 324 #if !DEFLATE_DEBUG
 325         if (state->debug)
 326 #endif
 327             printf("z_incomp%d: inflateIncomp returned %d (%s)\n",
 328                    state->unit, r, (state->strm.msg? state->strm.msg: ""));
 329         return;
 330     }
 331
 332     /*
 333      * Update stats.
 334      */
 335     if (proto <= 0xff)
 336         ++rlen;
 337     rlen += 2;
 338     state->stats.inc_bytes += rlen;
 339     state->stats.inc_packets++;
 340     state->stats.unc_bytes += rlen;
 341     state->stats.unc_packets++;
 342 }
 343
 344 #endif /* DO_DEFLATE */