2 * Copyright (c) 2002-2004 Jan Dubiec <jdx@slackware.pl>
3 * Copyright (c) 2007 Alexander Motin <mav@freebsd.org>
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice unmodified, this list of conditions, and the following
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * MPPC decompression library.
35 * Note that Hi/Fn (later acquired by Exar Corporation) held US patents
36 * on some implementation-critical aspects of MPPC compression.
37 * These patents lapsed due to non-payment of fees in 2007 and by 2015
41 #include <sys/param.h>
42 #include <sys/systm.h>
46 #define MPPE_HIST_LEN 8192
48 struct MPPC_decomp_state {
49 uint8_t hist[2*MPPE_HIST_LEN];
53 static uint32_t __inline
54 getbits(const uint8_t *buf, const uint32_t n, uint32_t *i, uint32_t *l)
56 static const uint32_t m[] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
62 res = (buf[*i] & m[ol]) >> (*l);
69 res = (buf[(*i)++] & m[ol]) << 8;
70 res = (res | buf[*i]) >> (*l);
76 static uint32_t __inline
77 getbyte(const uint8_t *buf, const uint32_t i, const uint32_t l)
82 return ((((buf[i] << 8) | buf[i+1]) >> l) & 0xff);
87 lamecopy(uint8_t *dst, uint8_t *src, uint32_t len)
93 size_t MPPC_SizeOfDecompressionHistory(void)
95 return (sizeof(struct MPPC_decomp_state));
98 void MPPC_InitDecompressionHistory(char *history)
100 struct MPPC_decomp_state *state = (struct MPPC_decomp_state*)history;
102 bzero(history, sizeof(struct MPPC_decomp_state));
103 state->histptr = MPPE_HIST_LEN;
106 int MPPC_Decompress(u_char **src, u_char **dst, u_long *srcCnt, u_long *dstCnt, char *history, int flags)
108 struct MPPC_decomp_state *state = (struct MPPC_decomp_state*)history;
109 uint32_t olen, off, len, bits, val, sig, i, l;
114 if ((flags & MPPC_RESTART_HISTORY) != 0) {
115 memcpy(state->hist, state->hist + MPPE_HIST_LEN, MPPE_HIST_LEN);
116 state->histptr = MPPE_HIST_LEN;
119 hist = state->hist + state->histptr;
124 val = getbyte(isrc, i++, l);
125 if (val < 0x80) { /* literal byte < 0x80 */
126 if (state->histptr < 2*MPPE_HIST_LEN) {
127 /* Copy uncompressed byte to the history. */
128 (state->hist)[(state->histptr)++] = (uint8_t) val;
130 /* Buffer overflow; drop packet. */
140 if (sig == 0x80) { /* literal byte >= 0x80 */
141 if (state->histptr < 2*MPPE_HIST_LEN) {
142 /* Copy uncompressed byte to the history. */
143 (state->hist)[(state->histptr)++] =
144 (uint8_t) (0x80|((val&0x3f)<<1)|getbits(isrc, 1 , &i ,&l));
146 /* buffer overflow; drop packet */
155 /* Not a literal byte so it must be an (offset,length) pair */
158 if (sig == 0xf0) { /* 10-bit offset; 0 <= offset < 64 */
159 off = (((val&0x0f)<<2)|getbits(isrc, 2 , &i ,&l));
162 if (sig == 0xe0) { /* 12-bit offset; 64 <= offset < 320 */
163 off = ((((val&0x0f)<<4)|getbits(isrc, 4 , &i ,&l))+64);
166 if ((sig&0xe0) == 0xc0) {/* 16-bit offset; 320 <= offset < 8192 */
167 off = ((((val&0x1f)<<8)|getbyte(isrc, i++, l))+320);
169 if (off > MPPE_HIST_LEN - 1) {
173 } else { /* This shouldn't happen. */
179 /* Decode length of match. */
180 val = getbyte(isrc, i, l);
181 if ((val & 0x80) == 0x00) { /* len = 3 */
184 getbits(isrc, 1 , &i ,&l);
185 } else if ((val & 0xc0) == 0x80) { /* 4 <= len < 8 */
186 len = 0x04 | ((val>>4) & 0x03);
188 getbits(isrc, 4 , &i ,&l);
189 } else if ((val & 0xe0) == 0xc0) { /* 8 <= len < 16 */
190 len = 0x08 | ((val>>2) & 0x07);
192 getbits(isrc, 6 , &i ,&l);
193 } else if ((val & 0xf0) == 0xe0) { /* 16 <= len < 32 */
194 len = 0x10 | (val & 0x0f);
199 val = (val << 8) | getbyte(isrc, ++i, l);
200 if ((val & 0xf800) == 0xf000) { /* 32 <= len < 64 */
201 len = 0x0020 | ((val >> 6) & 0x001f);
203 getbits(isrc, 2 , &i ,&l);
204 } else if ((val & 0xfc00) == 0xf800) { /* 64 <= len < 128 */
205 len = 0x0040 | ((val >> 4) & 0x003f);
207 getbits(isrc, 4 , &i ,&l);
208 } else if ((val & 0xfe00) == 0xfc00) { /* 128 <= len < 256 */
209 len = 0x0080 | ((val >> 2) & 0x007f);
211 getbits(isrc, 6 , &i ,&l);
212 } else if ((val & 0xff00) == 0xfe00) { /* 256 <= len < 512 */
213 len = 0x0100 | (val & 0x00ff);
218 val = (val << 8) | getbyte(isrc, ++i, l);
219 if ((val & 0xff8000) == 0xff0000) { /* 512 <= len < 1024 */
220 len = 0x000200 | ((val >> 6) & 0x0001ff);
222 getbits(isrc, 2 , &i ,&l);
223 } else if ((val & 0xffc000) == 0xff8000) {/* 1024 <= len < 2048 */
224 len = 0x000400 | ((val >> 4) & 0x0003ff);
226 getbits(isrc, 4 , &i ,&l);
227 } else if ((val & 0xffe000) == 0xffc000) {/* 2048 <= len < 4096 */
228 len = 0x000800 | ((val >> 2) & 0x0007ff);
230 getbits(isrc, 6 , &i ,&l);
231 } else if ((val & 0xfff000) == 0xffe000) {/* 4096 <= len < 8192 */
232 len = 0x001000 | (val & 0x000fff);
235 } else { /* NOTREACHED */
242 s = state->hist + state->histptr;
243 state->histptr += len;
245 if (state->histptr < 2*MPPE_HIST_LEN) {
246 /* Copy uncompressed bytes to the history. */
249 * In some cases len may be greater than off. It means that memory
250 * areas pointed by s and s-off overlap. To decode that strange case
251 * data should be copied exactly by address increasing to make
252 * some data repeated.
254 lamecopy(s, s - off, len);
256 /* Buffer overflow; drop packet. */
262 /* Do PFC decompression. */
264 if ((hist[0] & 0x01) != 0) {
270 if (len <= *dstCnt) {
271 /* Copy uncompressed packet to the output buffer. */
272 memcpy(*dst, hist, olen);
274 /* Buffer overflow; drop packet. */
275 rtn |= MPPC_DEST_EXHAUSTED;