diff options
Diffstat (limited to 'sys/net/mppcd.c')
| -rw-r--r-- | sys/net/mppcd.c | 284 |
1 files changed, 284 insertions, 0 deletions
diff --git a/sys/net/mppcd.c b/sys/net/mppcd.c new file mode 100644 index 0000000..c1730e5 --- /dev/null +++ b/sys/net/mppcd.c @@ -0,0 +1,284 @@ +/*- + * Copyright (c) 2002-2004 Jan Dubiec <jdx@slackware.pl> + * Copyright (c) 2007 Alexander Motin <mav@freebsd.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice unmodified, this list of conditions, and the following + * disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +/* + * MPPC decompression library. + * Version 1.0 + * + * Note that Hi/Fn (later acquired by Exar Corporation) held US patents + * on some implementation-critical aspects of MPPC compression. + * These patents lapsed due to non-payment of fees in 2007 and by 2015 + * expired altogether. + */ + +#include <sys/param.h> +#include <sys/systm.h> + +#include <net/mppc.h> + +#define MPPE_HIST_LEN 8192 + +struct MPPC_decomp_state { + uint8_t hist[2*MPPE_HIST_LEN]; + uint16_t histptr; +}; + +static uint32_t __inline +getbits(const uint8_t *buf, const uint32_t n, uint32_t *i, uint32_t *l) +{ + static const uint32_t m[] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff}; + uint32_t res, ol; + + ol = *l; + if (*l >= n) { + *l = (*l) - n; + res = (buf[*i] & m[ol]) >> (*l); + if (*l == 0) { + *l = 8; + (*i)++; + } + } else { + *l = 8 - n + (*l); + res = (buf[(*i)++] & m[ol]) << 8; + res = (res | buf[*i]) >> (*l); + } + + return (res); +} + +static uint32_t __inline +getbyte(const uint8_t *buf, const uint32_t i, const uint32_t l) +{ + if (l == 8) { + return (buf[i]); + } else { + return ((((buf[i] << 8) | buf[i+1]) >> l) & 0xff); + } +} + +static void __inline +lamecopy(uint8_t *dst, uint8_t *src, uint32_t len) +{ + while (len--) + *dst++ = *src++; +} + +size_t MPPC_SizeOfDecompressionHistory(void) +{ + return (sizeof(struct MPPC_decomp_state)); +} + +void MPPC_InitDecompressionHistory(char *history) +{ + struct MPPC_decomp_state *state = (struct MPPC_decomp_state*)history; + + bzero(history, sizeof(struct MPPC_decomp_state)); + state->histptr = MPPE_HIST_LEN; +} + +int MPPC_Decompress(u_char **src, u_char **dst, u_long *srcCnt, u_long *dstCnt, char *history, int flags) +{ + struct MPPC_decomp_state *state = (struct MPPC_decomp_state*)history; + uint32_t olen, off, len, bits, val, sig, i, l; + uint8_t *hist, *s; + u_char *isrc = *src; + int rtn = MPPC_OK; + + if ((flags & MPPC_RESTART_HISTORY) != 0) { + memcpy(state->hist, state->hist + MPPE_HIST_LEN, MPPE_HIST_LEN); + state->histptr = MPPE_HIST_LEN; + } + + hist = state->hist + state->histptr; + olen = len = i = 0; + l = 8; + bits = *srcCnt * 8; + while (bits >= 8) { + val = getbyte(isrc, i++, l); + if (val < 0x80) { /* literal byte < 0x80 */ + if (state->histptr < 2*MPPE_HIST_LEN) { + /* Copy uncompressed byte to the history. */ + (state->hist)[(state->histptr)++] = (uint8_t) val; + } else { + /* Buffer overflow; drop packet. */ + rtn &= ~MPPC_OK; + return rtn; + } + olen++; + bits -= 8; + continue; + } + + sig = val & 0xc0; + if (sig == 0x80) { /* literal byte >= 0x80 */ + if (state->histptr < 2*MPPE_HIST_LEN) { + /* Copy uncompressed byte to the history. */ + (state->hist)[(state->histptr)++] = + (uint8_t) (0x80|((val&0x3f)<<1)|getbits(isrc, 1 , &i ,&l)); + } else { + /* buffer overflow; drop packet */ + rtn &= ~MPPC_OK; + return (rtn); + } + olen++; + bits -= 9; + continue; + } + + /* Not a literal byte so it must be an (offset,length) pair */ + /* decode offset */ + sig = val & 0xf0; + if (sig == 0xf0) { /* 10-bit offset; 0 <= offset < 64 */ + off = (((val&0x0f)<<2)|getbits(isrc, 2 , &i ,&l)); + bits -= 10; + } else { + if (sig == 0xe0) { /* 12-bit offset; 64 <= offset < 320 */ + off = ((((val&0x0f)<<4)|getbits(isrc, 4 , &i ,&l))+64); + bits -= 12; + } else { + if ((sig&0xe0) == 0xc0) {/* 16-bit offset; 320 <= offset < 8192 */ + off = ((((val&0x1f)<<8)|getbyte(isrc, i++, l))+320); + bits -= 16; + if (off > MPPE_HIST_LEN - 1) { + rtn &= ~MPPC_OK; + return (rtn); + } + } else { /* NOTREACHED */ + rtn &= ~MPPC_OK; + return (rtn); + } + } + } + /* Decode length of match. */ + val = getbyte(isrc, i, l); + if ((val & 0x80) == 0x00) { /* len = 3 */ + len = 3; + bits--; + getbits(isrc, 1 , &i ,&l); + } else if ((val & 0xc0) == 0x80) { /* 4 <= len < 8 */ + len = 0x04 | ((val>>4) & 0x03); + bits -= 4; + getbits(isrc, 4 , &i ,&l); + } else if ((val & 0xe0) == 0xc0) { /* 8 <= len < 16 */ + len = 0x08 | ((val>>2) & 0x07); + bits -= 6; + getbits(isrc, 6 , &i ,&l); + } else if ((val & 0xf0) == 0xe0) { /* 16 <= len < 32 */ + len = 0x10 | (val & 0x0f); + bits -= 8; + i++; + } else { + bits -= 8; + val = (val << 8) | getbyte(isrc, ++i, l); + if ((val & 0xf800) == 0xf000) { /* 32 <= len < 64 */ + len = 0x0020 | ((val >> 6) & 0x001f); + bits -= 2; + getbits(isrc, 2 , &i ,&l); + } else if ((val & 0xfc00) == 0xf800) { /* 64 <= len < 128 */ + len = 0x0040 | ((val >> 4) & 0x003f); + bits -= 4; + getbits(isrc, 4 , &i ,&l); + } else if ((val & 0xfe00) == 0xfc00) { /* 128 <= len < 256 */ + len = 0x0080 | ((val >> 2) & 0x007f); + bits -= 6; + getbits(isrc, 6 , &i ,&l); + } else if ((val & 0xff00) == 0xfe00) { /* 256 <= len < 512 */ + len = 0x0100 | (val & 0x00ff); + bits -= 8; + i++; + } else { + bits -= 8; + val = (val << 8) | getbyte(isrc, ++i, l); + if ((val & 0xff8000) == 0xff0000) { /* 512 <= len < 1024 */ + len = 0x000200 | ((val >> 6) & 0x0001ff); + bits -= 2; + getbits(isrc, 2 , &i ,&l); + } else if ((val & 0xffc000) == 0xff8000) {/* 1024 <= len < 2048 */ + len = 0x000400 | ((val >> 4) & 0x0003ff); + bits -= 4; + getbits(isrc, 4 , &i ,&l); + } else if ((val & 0xffe000) == 0xffc000) {/* 2048 <= len < 4096 */ + len = 0x000800 | ((val >> 2) & 0x0007ff); + bits -= 6; + getbits(isrc, 6 , &i ,&l); + } else if ((val & 0xfff000) == 0xffe000) {/* 4096 <= len < 8192 */ + len = 0x001000 | (val & 0x000fff); + bits -= 8; + i++; + } else { /* NOTREACHED */ + rtn &= ~MPPC_OK; + return (rtn); + } + } + } + + s = state->hist + state->histptr; + state->histptr += len; + olen += len; + if (state->histptr < 2*MPPE_HIST_LEN) { + /* Copy uncompressed bytes to the history. */ + + /* + * In some cases len may be greater than off. It means that memory + * areas pointed by s and s-off overlap. To decode that strange case + * data should be copied exactly by address increasing to make + * some data repeated. + */ + lamecopy(s, s - off, len); + } else { + /* Buffer overflow; drop packet. */ + rtn &= ~MPPC_OK; + return (rtn); + } + } + + /* Do PFC decompression. */ + len = olen; + if ((hist[0] & 0x01) != 0) { + (*dst)[0] = 0; + (*dst)++; + len++; + } + + if (len <= *dstCnt) { + /* Copy uncompressed packet to the output buffer. */ + memcpy(*dst, hist, olen); + } else { + /* Buffer overflow; drop packet. */ + rtn |= MPPC_DEST_EXHAUSTED; + } + + *src += *srcCnt; + *srcCnt = 0; + *dst += len; + *dstCnt -= len; + + return (rtn); +} |
