/*
* Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2008-2013 Sourcefire, Inc.
*
* Authors: Alberto Wu
*
* Acknowledgements: Written from scratch based on specs from PKWARE:
* http://www.pkware.com/documents/casestudies/APPNOTE.TXT
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
/*
* Written from scratch based on specs from PKWARE:
* see www.pkware.com/documents/casestudies/APPNOTE.TXT
*
* To the best of my knowledge, it's patent free:
* http://www.unisys.com/about__unisys/lzw
*/
/* To Cami and Dario, the only lawyers I can stand */
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#if HAVE_STRING_H
#include <string.h>
#endif
#include "clamav.h"
#include "explode.h"
#include "others.h"
/* NOTE: sorting algo must be stable! */
static void bs(uint8_t *k, uint8_t *v, unsigned int elements)
{
uint8_t tmp;
unsigned int i = 0, l = 0, stop = 0, r = elements;
while (!stop) {
stop = 1;
for (; i < r; i++) {
if (v[k[i]] > v[k[i + 1]]) {
tmp = k[i];
k[i] = k[i + 1];
k[i + 1] = tmp;
stop = 0;
}
}
if (stop) break;
r--;
i--;
for (; i > l; i--) {
if (v[k[i]] < v[k[i - 1]]) {
tmp = k[i];
k[i] = k[i - 1];
k[i - 1] = tmp;
stop = 0;
}
}
l++;
i++;
}
}
static int unpack_tree(struct xplstate *X, uint32_t *tree, unsigned int expected)
{
uint8_t temptree[256], order[256], *ttree = temptree;
uint8_t *cur = X->window;
uint8_t packsz;
unsigned int i;
uint16_t code = 0, codeinc = 0, lastlen = 0;
packsz = *cur++;
for (i = 0; i < expected; i++) order[i] = i;
i = expected;
do {
uint8_t values, len;
values = *cur++;
len = (values & 15) + 1;
values = (values >> 4) + 1;
if (values > i) return 1;
i -= values;
while (values--)
*ttree++ = len;
} while (packsz--);
if (i) return 1;
bs(order, temptree, expected - 1);
i = expected - 1;
do {
code = code + codeinc;
if (temptree[order[i]] != lastlen) {
lastlen = temptree[order[i]];
codeinc = 1 << (16 - lastlen);
}
tree[order[i]] = code | ((uint32_t)lastlen << 16);
} while (i--);
return 0;
}
/* bit lame of a lookup, but prolly not worth optimizing */
static int lookup_tree(uint32_t *tree, unsigned int size, uint16_t code, uint8_t len)
{
uint32_t lookup = ((uint32_t)(len + 1)) << 16 | code;
unsigned int i;
for (i = 0; i < size; i++)
if (tree[i] == lookup) return i;
return -1;
}
int explode_init(struct xplstate *X, uint16_t flags)
{
X->bits = X->cur = 0;
if (flags & 2) {
X->largewin = 1;
X->mask = 0x1fff;
} else {
X->largewin = 0;
X->mask = 0xfff;
}
if (flags & 4) {
X->state = GRABLITS;
X->litcodes = 1;
X->minlen = 3;
} else {
X->state = GRABLENS;
X->litcodes = 0;
X->minlen = 2;
}
X->got = 0;
return EXPLODE_OK;
}
#define GETBIT \
if (X->bits) { \
X->bits--; \
val = X->bitmap & 1; \
X->bitmap >>= 1; \
} else { \
if (!X->avail_in) return EXPLODE_EBUFF; \
if (X->avail_in >= 4) { \
X->bitmap = cli_readint32(X->next_in); \
X->bits = 31; \
X->next_in += 4; \
X->avail_in -= 4; \
} else { \
X->bitmap = *X->next_in; \
X->bits = 7; \
X->next_in++; \
X->avail_in--; \
} \
val = X->bitmap & 1; \
X->bitmap >>= 1; \
}
#define GETBITS(NUM) \
if (X->bits >= (NUM)) { \
val = X->bitmap & ((1 << (NUM)) - 1); \
X->bitmap >>= (NUM); \
X->bits -= (NUM); \
} else { \
if (X->avail_in * 8 + X->bits < (NUM)) return EXPLODE_EBUFF; \
val = X->bitmap; \
if (X->avail_in >= 4) { \
X->bitmap = cli_readint32(X->next_in); \
X->next_in += 4; \
X->avail_in -= 4; \
val |= (X->bitmap & ((1 << ((NUM)-X->bits)) - 1)) << X->bits; \
X->bitmap >>= (NUM)-X->bits; \
X->bits = 32 - ((NUM)-X->bits); \
} else { \
X->bitmap = *X->next_in; \
X->next_in++; \
X->avail_in--; \
val |= (X->bitmap & ((1 << ((NUM)-X->bits)) - 1)) << X->bits; \
X->bitmap >>= (NUM)-X->bits; \
X->bits = 8 - ((NUM)-X->bits); \
} \
}
#define GETCODES(CASE, WHICH, HOWMANY) \
case CASE: { \
if (!X->avail_in) return EXPLODE_EBUFF; \
if (!X->got) \
need = *X->next_in; \
else \
need = X->window[0]; \
if (need > HOWMANY - 1) return EXPLODE_ESTREAM; /* too many codes */ \
need = need + 2 - X->got; /* bytes remaining */ \
if (need > X->avail_in) { /* if not enuff */ \
/* just copy what's avail... */ \
memcpy(&X->window[X->got], X->next_in, X->avail_in); \
X->got += X->avail_in; \
X->next_in += X->avail_in; \
X->avail_in = 0; \
return EXPLODE_EBUFF; /* ...and beg for more */ \
} \
/* else fetch what's needed */ \
memcpy(&X->window[X->got], X->next_in, need); \
X->avail_in -= need; \
X->next_in += need; \
if (unpack_tree(X, X->WHICH, HOWMANY)) return EXPLODE_ESTREAM; \
/* and move on */ \
X->got = 0; \
X->state++; \
}
#define SETCASE(CASE) \
X->state = (CASE); \
case (CASE): { /* FAKE */ \
}
int explode(struct xplstate *X)
{
unsigned int val, need;
int temp = -1;
switch (X->state) {
/* grab compressed coded literals, if present */
GETCODES(GRABLITS, lit_tree, 256);
/* grab compressed coded lens */
GETCODES(GRABLENS, len_tree, 64);
/* grab compressed coded dists */
GETCODES(GRABDISTS, dist_tree, 64);
case EXPLODE:
while (X->avail_in || X->bits) {
GETBIT; /* can't fail */
if (val) {
if (X->litcodes) {
X->backsize = 0;
X->state = EXPLODE_LITCODES;
for (X->got = 0; X->got <= 15; X->got++) {
case EXPLODE_LITCODES:
GETBIT;
X->backsize |= val << (15 - X->got);
if ((temp = lookup_tree(X->lit_tree, 256, X->backsize, X->got)) != -1) break;
}
if (temp == -1) return EXPLODE_ESTREAM;
X->got = temp;
} else {
SETCASE(EXPLODE_LITS);
GETBITS(8);
X->got = val;
}
SETCASE(EXPLODE_WBYTE);
if (!X->avail_out) return EXPLODE_EBUFF;
X->avail_out--;
*X->next_out = X->window[X->cur & X->mask] = X->got;
X->cur++;
X->next_out++;
} else {
SETCASE(EXPLODE_BASEDIST);
GETBITS(6u + X->largewin);
X->backbytes = val;
X->backsize = 0;
X->state = EXPLODE_DECODEDISTS;
for (X->got = 0; X->got <= 15; X->got++) {
case EXPLODE_DECODEDISTS:
GETBIT;
X->backsize |= val << (15 - X->got);
if ((temp = lookup_tree(X->dist_tree, 64, X->backsize, X->got)) != -1) break;
}
if (temp == -1) return EXPLODE_ESTREAM;
X->backbytes |= temp << (6 + X->largewin);
X->backbytes++;
X->backsize = 0;
X->state = EXPLODE_DECODELENS;
for (X->got = 0; X->got <= 15; X->got++) {
case EXPLODE_DECODELENS:
GETBIT;
X->backsize |= val << (15 - X->got);
if ((temp = lookup_tree(X->len_tree, 64, X->backsize, X->got)) != -1) break;
}
if (temp == -1) return EXPLODE_ESTREAM;
if (temp == 63) {
SETCASE(EXPLODE_DECODEEXTRA);
GETBITS(8);
temp = 63 + val;
}
X->backsize = temp + X->minlen;
X->state = EXPLODE_BACKCOPY;
while (X->backsize--) {
case EXPLODE_BACKCOPY:
if (!X->avail_out) return EXPLODE_EBUFF;
X->avail_out--;
if (X->cur >= X->backbytes)
*X->next_out = X->window[X->cur & X->mask] = X->window[(X->cur - X->backbytes) & X->mask];
else
*X->next_out = X->window[X->cur & X->mask] = 0;
X->cur++;
X->next_out++;
}
}
X->state = EXPLODE;
}
}
return EXPLODE_EBUFF;
}
void explode_shutdown(void) {}