1 /*-
2 * Copyright (c) 2002-2004 Jan Dubiec <jdx@slackware.pl>
3 * Copyright (c) 2007 Alexander Motin <mav@freebsd.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice unmodified, this list of conditions, and the following
11 * disclaimer.
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.
15 *
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
26 * SUCH DAMAGE.
27 */
28
29 /*
30 * MPPC decompression library.
31 * Version 1.0
32 *
33 * Note that Hi/Fn (later acquired by Exar Corporation) held US patents
34 * on some implementation-critical aspects of MPPC compression.
35 * These patents lapsed due to non-payment of fees in 2007 and by 2015
36 * expired altogether.
37 */
38
39 #include <sys/param.h>
40 #include <sys/systm.h>
41
42 #include <net/mppc.h>
43
44 #define MPPE_HIST_LEN 8192
45
46 struct MPPC_decomp_state {
47 uint8_t hist[2*MPPE_HIST_LEN];
48 uint16_t histptr;
49 };
50
51 static uint32_t __inline
getbits(const uint8_t * buf,const uint32_t n,uint32_t * i,uint32_t * l)52 getbits(const uint8_t *buf, const uint32_t n, uint32_t *i, uint32_t *l)
53 {
54 static const uint32_t m[] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
55 uint32_t res, ol;
56
57 ol = *l;
58 if (*l >= n) {
59 *l = (*l) - n;
60 res = (buf[*i] & m[ol]) >> (*l);
61 if (*l == 0) {
62 *l = 8;
63 (*i)++;
64 }
65 } else {
66 *l = 8 - n + (*l);
67 res = (buf[(*i)++] & m[ol]) << 8;
68 res = (res | buf[*i]) >> (*l);
69 }
70
71 return (res);
72 }
73
74 static uint32_t __inline
getbyte(const uint8_t * buf,const uint32_t i,const uint32_t l)75 getbyte(const uint8_t *buf, const uint32_t i, const uint32_t l)
76 {
77 if (l == 8) {
78 return (buf[i]);
79 } else {
80 return ((((buf[i] << 8) | buf[i+1]) >> l) & 0xff);
81 }
82 }
83
84 static void __inline
lamecopy(uint8_t * dst,uint8_t * src,uint32_t len)85 lamecopy(uint8_t *dst, uint8_t *src, uint32_t len)
86 {
87 while (len--)
88 *dst++ = *src++;
89 }
90
MPPC_SizeOfDecompressionHistory(void)91 size_t MPPC_SizeOfDecompressionHistory(void)
92 {
93 return (sizeof(struct MPPC_decomp_state));
94 }
95
MPPC_InitDecompressionHistory(char * history)96 void MPPC_InitDecompressionHistory(char *history)
97 {
98 struct MPPC_decomp_state *state = (struct MPPC_decomp_state*)history;
99
100 bzero(history, sizeof(struct MPPC_decomp_state));
101 state->histptr = MPPE_HIST_LEN;
102 }
103
MPPC_Decompress(u_char ** src,u_char ** dst,u_long * srcCnt,u_long * dstCnt,char * history,int flags)104 int MPPC_Decompress(u_char **src, u_char **dst, u_long *srcCnt, u_long *dstCnt, char *history, int flags)
105 {
106 struct MPPC_decomp_state *state = (struct MPPC_decomp_state*)history;
107 uint32_t olen, off, len, bits, val, sig, i, l;
108 uint8_t *hist, *s;
109 u_char *isrc = *src;
110 int rtn = MPPC_OK;
111
112 if ((flags & MPPC_RESTART_HISTORY) != 0) {
113 memcpy(state->hist, state->hist + MPPE_HIST_LEN, MPPE_HIST_LEN);
114 state->histptr = MPPE_HIST_LEN;
115 }
116
117 hist = state->hist + state->histptr;
118 olen = len = i = 0;
119 l = 8;
120 bits = *srcCnt * 8;
121 while (bits >= 8) {
122 val = getbyte(isrc, i++, l);
123 if (val < 0x80) { /* literal byte < 0x80 */
124 if (state->histptr < 2*MPPE_HIST_LEN) {
125 /* Copy uncompressed byte to the history. */
126 (state->hist)[(state->histptr)++] = (uint8_t) val;
127 } else {
128 /* Buffer overflow; drop packet. */
129 rtn &= ~MPPC_OK;
130 return rtn;
131 }
132 olen++;
133 bits -= 8;
134 continue;
135 }
136
137 sig = val & 0xc0;
138 if (sig == 0x80) { /* literal byte >= 0x80 */
139 if (state->histptr < 2*MPPE_HIST_LEN) {
140 /* Copy uncompressed byte to the history. */
141 (state->hist)[(state->histptr)++] =
142 (uint8_t) (0x80|((val&0x3f)<<1)|getbits(isrc, 1 , &i ,&l));
143 } else {
144 /* buffer overflow; drop packet */
145 rtn &= ~MPPC_OK;
146 return (rtn);
147 }
148 olen++;
149 bits -= 9;
150 continue;
151 }
152
153 /* Not a literal byte so it must be an (offset,length) pair */
154 /* decode offset */
155 sig = val & 0xf0;
156 if (sig == 0xf0) { /* 10-bit offset; 0 <= offset < 64 */
157 off = (((val&0x0f)<<2)|getbits(isrc, 2 , &i ,&l));
158 bits -= 10;
159 } else {
160 if (sig == 0xe0) { /* 12-bit offset; 64 <= offset < 320 */
161 off = ((((val&0x0f)<<4)|getbits(isrc, 4 , &i ,&l))+64);
162 bits -= 12;
163 } else {
164 if ((sig&0xe0) == 0xc0) {/* 16-bit offset; 320 <= offset < 8192 */
165 off = ((((val&0x1f)<<8)|getbyte(isrc, i++, l))+320);
166 bits -= 16;
167 if (off > MPPE_HIST_LEN - 1) {
168 rtn &= ~MPPC_OK;
169 return (rtn);
170 }
171 } else { /* This shouldn't happen. */
172 rtn &= ~MPPC_OK;
173 return (rtn);
174 }
175 }
176 }
177 /* Decode length of match. */
178 val = getbyte(isrc, i, l);
179 if ((val & 0x80) == 0x00) { /* len = 3 */
180 len = 3;
181 bits--;
182 getbits(isrc, 1 , &i ,&l);
183 } else if ((val & 0xc0) == 0x80) { /* 4 <= len < 8 */
184 len = 0x04 | ((val>>4) & 0x03);
185 bits -= 4;
186 getbits(isrc, 4 , &i ,&l);
187 } else if ((val & 0xe0) == 0xc0) { /* 8 <= len < 16 */
188 len = 0x08 | ((val>>2) & 0x07);
189 bits -= 6;
190 getbits(isrc, 6 , &i ,&l);
191 } else if ((val & 0xf0) == 0xe0) { /* 16 <= len < 32 */
192 len = 0x10 | (val & 0x0f);
193 bits -= 8;
194 i++;
195 } else {
196 bits -= 8;
197 val = (val << 8) | getbyte(isrc, ++i, l);
198 if ((val & 0xf800) == 0xf000) { /* 32 <= len < 64 */
199 len = 0x0020 | ((val >> 6) & 0x001f);
200 bits -= 2;
201 getbits(isrc, 2 , &i ,&l);
202 } else if ((val & 0xfc00) == 0xf800) { /* 64 <= len < 128 */
203 len = 0x0040 | ((val >> 4) & 0x003f);
204 bits -= 4;
205 getbits(isrc, 4 , &i ,&l);
206 } else if ((val & 0xfe00) == 0xfc00) { /* 128 <= len < 256 */
207 len = 0x0080 | ((val >> 2) & 0x007f);
208 bits -= 6;
209 getbits(isrc, 6 , &i ,&l);
210 } else if ((val & 0xff00) == 0xfe00) { /* 256 <= len < 512 */
211 len = 0x0100 | (val & 0x00ff);
212 bits -= 8;
213 i++;
214 } else {
215 bits -= 8;
216 val = (val << 8) | getbyte(isrc, ++i, l);
217 if ((val & 0xff8000) == 0xff0000) { /* 512 <= len < 1024 */
218 len = 0x000200 | ((val >> 6) & 0x0001ff);
219 bits -= 2;
220 getbits(isrc, 2 , &i ,&l);
221 } else if ((val & 0xffc000) == 0xff8000) {/* 1024 <= len < 2048 */
222 len = 0x000400 | ((val >> 4) & 0x0003ff);
223 bits -= 4;
224 getbits(isrc, 4 , &i ,&l);
225 } else if ((val & 0xffe000) == 0xffc000) {/* 2048 <= len < 4096 */
226 len = 0x000800 | ((val >> 2) & 0x0007ff);
227 bits -= 6;
228 getbits(isrc, 6 , &i ,&l);
229 } else if ((val & 0xfff000) == 0xffe000) {/* 4096 <= len < 8192 */
230 len = 0x001000 | (val & 0x000fff);
231 bits -= 8;
232 i++;
233 } else { /* NOTREACHED */
234 rtn &= ~MPPC_OK;
235 return (rtn);
236 }
237 }
238 }
239
240 s = state->hist + state->histptr;
241 state->histptr += len;
242 olen += len;
243 if (state->histptr < 2*MPPE_HIST_LEN) {
244 /* Copy uncompressed bytes to the history. */
245
246 /*
247 * In some cases len may be greater than off. It means that memory
248 * areas pointed by s and s-off overlap. To decode that strange case
249 * data should be copied exactly by address increasing to make
250 * some data repeated.
251 */
252 lamecopy(s, s - off, len);
253 } else {
254 /* Buffer overflow; drop packet. */
255 rtn &= ~MPPC_OK;
256 return (rtn);
257 }
258 }
259
260 /* Do PFC decompression. */
261 len = olen;
262 if ((hist[0] & 0x01) != 0) {
263 (*dst)[0] = 0;
264 (*dst)++;
265 len++;
266 }
267
268 if (len <= *dstCnt) {
269 /* Copy uncompressed packet to the output buffer. */
270 memcpy(*dst, hist, olen);
271 } else {
272 /* Buffer overflow; drop packet. */
273 rtn |= MPPC_DEST_EXHAUSTED;
274 }
275
276 *src += *srcCnt;
277 *srcCnt = 0;
278 *dst += len;
279 *dstCnt -= len;
280
281 return (rtn);
282 }
283