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 *
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
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
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 *
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
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
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
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
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
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