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 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 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 85 lamecopy(uint8_t *dst, uint8_t *src, uint32_t len) 86 { 87 while (len--) 88 *dst++ = *src++; 89 } 90 91 size_t MPPC_SizeOfDecompressionHistory(void) 92 { 93 return (sizeof(struct MPPC_decomp_state)); 94 } 95 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 } 103 104 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