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 #ifdef PPP_DEFS_IN_NET
35 #include <net/ppp_defs.h>
36 #else
37 #include "ppp_defs.h"
38 #endif
39 #include "ppp-comp.h"
40 #include "zlib.h"
41
42 #if DO_DEFLATE
43
44 #define DEFLATE_DEBUG 1
45
46 /*
47 * State for a Deflate (de)compressor.
48 */
49 struct deflate_state {
50 int seqno;
51 int w_size;
52 int unit;
53 int hdrlen;
54 int mru;
55 int debug;
56 z_stream strm;
57 struct compstat stats;
58 };
59
60 #define DEFLATE_OVHD 2 /* Deflate overhead/packet */
61
62 static void *z_alloc __P((void *, u_int items, u_int size));
63 static void z_free __P((void *, void *ptr, u_int nb));
64 static void *z_decomp_alloc __P((u_char *options, int opt_len));
65 static void z_decomp_free __P((void *state));
66 static int z_decomp_init __P((void *state, u_char *options, int opt_len,
67 int unit, int hdrlen, int mru, int debug));
68 static void z_incomp __P((void *state, u_char *dmsg, int len));
69 static int z_decompress __P((void *state, u_char *cmp, int inlen,
70 u_char *dmp, int *outlenp));
71 static void z_decomp_reset __P((void *state));
72 static void z_comp_stats __P((void *state, struct compstat *stats));
73
74 /*
75 * Procedures exported to if_ppp.c.
76 */
77 struct compressor ppp_deflate = {
78 CI_DEFLATE, /* compress_proto */
79 z_decomp_alloc, /* decomp_alloc */
80 z_decomp_free, /* decomp_free */
81 z_decomp_init, /* decomp_init */
82 z_decomp_reset, /* decomp_reset */
83 z_decompress, /* decompress */
84 z_incomp, /* incomp */
85 z_comp_stats, /* decomp_stat */
86 };
87
88 /*
89 * Space allocation and freeing routines for use by zlib routines.
90 */
91 static void *
z_alloc(notused,items,size)92 z_alloc(notused, items, size)
93 void *notused;
94 u_int items, size;
95 {
96 return malloc(items * size);
97 }
98
99 static void
z_free(notused,ptr,nbytes)100 z_free(notused, ptr, nbytes)
101 void *notused;
102 void *ptr;
103 u_int nbytes;
104 {
105 free(ptr);
106 }
107
108 static void
z_comp_stats(arg,stats)109 z_comp_stats(arg, stats)
110 void *arg;
111 struct compstat *stats;
112 {
113 struct deflate_state *state = (struct deflate_state *) arg;
114 u_int out;
115
116 *stats = state->stats;
117 stats->ratio = stats->unc_bytes;
118 out = stats->comp_bytes + stats->unc_bytes;
119 if (stats->ratio <= 0x7ffffff)
120 stats->ratio <<= 8;
121 else
122 out >>= 8;
123 if (out != 0)
124 stats->ratio /= out;
125 }
126
127 /*
128 * Allocate space for a decompressor.
129 */
130 static void *
z_decomp_alloc(options,opt_len)131 z_decomp_alloc(options, opt_len)
132 u_char *options;
133 int opt_len;
134 {
135 struct deflate_state *state;
136 int w_size;
137
138 if (opt_len != CILEN_DEFLATE || options[0] != CI_DEFLATE
139 || options[1] != CILEN_DEFLATE
140 || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
141 || options[3] != DEFLATE_CHK_SEQUENCE)
142 return NULL;
143 w_size = DEFLATE_SIZE(options[2]);
144 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
145 return NULL;
146
147 state = (struct deflate_state *) malloc(sizeof(*state));
148 if (state == NULL)
149 return NULL;
150
151 state->strm.next_out = NULL;
152 state->strm.zalloc = (alloc_func) z_alloc;
153 state->strm.zfree = (free_func) z_free;
154 if (inflateInit2(&state->strm, -w_size) != Z_OK) {
155 free(state);
156 return NULL;
157 }
158
159 state->w_size = w_size;
160 memset(&state->stats, 0, sizeof(state->stats));
161 return (void *) state;
162 }
163
164 static void
z_decomp_free(arg)165 z_decomp_free(arg)
166 void *arg;
167 {
168 struct deflate_state *state = (struct deflate_state *) arg;
169
170 inflateEnd(&state->strm);
171 free(state);
172 }
173
174 static int
z_decomp_init(arg,options,opt_len,unit,hdrlen,mru,debug)175 z_decomp_init(arg, options, opt_len, unit, hdrlen, mru, debug)
176 void *arg;
177 u_char *options;
178 int opt_len, unit, hdrlen, mru, debug;
179 {
180 struct deflate_state *state = (struct deflate_state *) arg;
181
182 if (opt_len < CILEN_DEFLATE || options[0] != CI_DEFLATE
183 || options[1] != CILEN_DEFLATE
184 || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
185 || DEFLATE_SIZE(options[2]) != state->w_size
186 || options[3] != DEFLATE_CHK_SEQUENCE)
187 return 0;
188
189 state->seqno = 0;
190 state->unit = unit;
191 state->hdrlen = hdrlen;
192 state->debug = debug;
193 state->mru = mru;
194
195 inflateReset(&state->strm);
196
197 return 1;
198 }
199
200 static void
z_decomp_reset(arg)201 z_decomp_reset(arg)
202 void *arg;
203 {
204 struct deflate_state *state = (struct deflate_state *) arg;
205
206 state->seqno = 0;
207 inflateReset(&state->strm);
208 }
209
210 /*
211 * Decompress a Deflate-compressed packet.
212 *
213 * Because of patent problems, we return DECOMP_ERROR for errors
214 * found by inspecting the input data and for system problems, but
215 * DECOMP_FATALERROR for any errors which could possibly be said to
216 * be being detected "after" decompression. For DECOMP_ERROR,
217 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
218 * infringing a patent of Motorola's if we do, so we take CCP down
219 * instead.
220 *
221 * Given that the frame has the correct sequence number and a good FCS,
222 * errors such as invalid codes in the input most likely indicate a
223 * bug, so we return DECOMP_FATALERROR for them in order to turn off
224 * compression, even though they are detected by inspecting the input.
225 */
226 static int
z_decompress(arg,mi,inlen,mo,outlenp)227 z_decompress(arg, mi, inlen, mo, outlenp)
228 void *arg;
229 u_char *mi, *mo;
230 int inlen, *outlenp;
231 {
232 struct deflate_state *state = (struct deflate_state *) arg;
233 u_char *rptr, *wptr;
234 int rlen, olen, ospace;
235 int seq, i, flush, r, decode_proto;
236
237 rptr = mi;
238 if (*rptr == 0)
239 ++rptr;
240 ++rptr;
241
242 /* Check the sequence number. */
243 seq = (rptr[0] << 8) + rptr[1];
244 rptr += 2;
245 if (seq != state->seqno) {
246 #if !DEFLATE_DEBUG
247 if (state->debug)
248 #endif
249 printf("z_decompress%d: bad seq # %d, expected %d\n",
250 state->unit, seq, state->seqno);
251 return DECOMP_ERROR;
252 }
253 ++state->seqno;
254
255 /*
256 * Set up to call inflate.
257 */
258 wptr = mo;
259 state->strm.next_in = rptr;
260 state->strm.avail_in = mi + inlen - rptr;
261 rlen = state->strm.avail_in + PPP_HDRLEN + DEFLATE_OVHD;
262 state->strm.next_out = wptr;
263 state->strm.avail_out = state->mru + 2;
264
265 r = inflate(&state->strm, Z_PACKET_FLUSH);
266 if (r != Z_OK) {
267 #if !DEFLATE_DEBUG
268 if (state->debug)
269 #endif
270 printf("z_decompress%d: inflate returned %d (%s)\n",
271 state->unit, r, (state->strm.msg? state->strm.msg: ""));
272 return DECOMP_FATALERROR;
273 }
274 olen = state->mru + 2 - state->strm.avail_out;
275 *outlenp = olen;
276
277 if ((wptr[0] & 1) != 0)
278 ++olen; /* for suppressed protocol high byte */
279 olen += 2; /* for address, control */
280
281 #if DEFLATE_DEBUG
282 if (olen > state->mru + PPP_HDRLEN)
283 printf("ppp_deflate%d: exceeded mru (%d > %d)\n",
284 state->unit, olen, state->mru + PPP_HDRLEN);
285 #endif
286
287 state->stats.unc_bytes += olen;
288 state->stats.unc_packets++;
289 state->stats.comp_bytes += rlen;
290 state->stats.comp_packets++;
291
292 return DECOMP_OK;
293 }
294
295 /*
296 * Incompressible data has arrived - add it to the history.
297 */
298 static void
z_incomp(arg,mi,mlen)299 z_incomp(arg, mi, mlen)
300 void *arg;
301 u_char *mi;
302 int mlen;
303 {
304 struct deflate_state *state = (struct deflate_state *) arg;
305 u_char *rptr;
306 int rlen, proto, r;
307
308 /*
309 * Check that the protocol is one we handle.
310 */
311 rptr = mi;
312 proto = rptr[0];
313 if ((proto & 1) == 0)
314 proto = (proto << 8) + rptr[1];
315 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
316 return;
317
318 ++state->seqno;
319
320 if (rptr[0] == 0)
321 ++rptr;
322 rlen = mi + mlen - rptr;
323 state->strm.next_in = rptr;
324 state->strm.avail_in = rlen;
325 r = inflateIncomp(&state->strm);
326 if (r != Z_OK) {
327 /* gak! */
328 #if !DEFLATE_DEBUG
329 if (state->debug)
330 #endif
331 printf("z_incomp%d: inflateIncomp returned %d (%s)\n",
332 state->unit, r, (state->strm.msg? state->strm.msg: ""));
333 return;
334 }
335
336 /*
337 * Update stats.
338 */
339 if (proto <= 0xff)
340 ++rlen;
341 rlen += 2;
342 state->stats.inc_bytes += rlen;
343 state->stats.inc_packets++;
344 state->stats.unc_bytes += rlen;
345 state->stats.unc_packets++;
346 }
347
348 #endif /* DO_DEFLATE */
349