mirror of https://github.com/Cisco-Talos/clamav
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317 lines
7.7 KiB
317 lines
7.7 KiB
/*
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* Copyright (C) 2015 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
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* Copyright (C) 2008 Sourcefire, Inc.
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*
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* Authors: Alberto Wu
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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/*
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* Written from scratch based on specs from PKWARE:
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* see www.pkware.com/documents/casestudies/APPNOTE.TXT
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*
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* To the best of my knowledge, it's patent free:
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* http://www.unisys.com/about__unisys/lzw
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*/
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/* To Cami and Dario, the only laywers I can stand */
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#if HAVE_CONFIG_H
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#include "clamav-config.h"
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#endif
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#if HAVE_STRING_H
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#include <string.h>
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#endif
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#include "clamav.h"
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#include "explode.h"
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#include "others.h"
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/* NOTE: sorting algo must be stable! */
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static void bs(uint8_t *k, uint8_t *v, unsigned int elements) {
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uint8_t tmp;
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unsigned int i=0, l=0, stop=0, r=elements;
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while(!stop) {
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stop=1;
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for(; i<r; i++) {
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if(v[k[i]]>v[k[i+1]]) {
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tmp=k[i];
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k[i]=k[i+1];
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k[i+1]=tmp;
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stop=0;
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}
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}
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if(stop) break;
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r--;
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i--;
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for(; i>l; i--) {
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if(v[k[i]]<v[k[i-1]]) {
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tmp=k[i];
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k[i]=k[i-1];
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k[i-1]=tmp;
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stop=0;
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}
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}
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l++;
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i++;
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}
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}
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static int unpack_tree(struct xplstate *X, uint32_t *tree, unsigned int expected) {
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uint8_t temptree[256], order[256], *ttree=temptree;
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uint8_t *cur=X->window;
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uint8_t packsz;
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unsigned int i;
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uint16_t code=0, codeinc=0, lastlen=0;
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packsz=*cur++;
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for(i=0; i<expected; i++) order[i]=i;
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i=expected;
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do {
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uint8_t values, len;
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values = *cur++;
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len = (values&15) + 1;
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values = (values>>4) + 1;
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if(values>i) return 1;
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i-=values;
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while(values--)
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*ttree++ = len;
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} while(packsz--);
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if(i) return 1;
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bs(order, temptree, expected-1);
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i=expected-1;
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do {
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code=code+codeinc;
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if(temptree[order[i]]!=lastlen) {
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lastlen=temptree[order[i]];
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codeinc=1<<(16-lastlen);
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}
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tree[order[i]]=code | ((uint32_t)lastlen<<16);
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} while(i--);
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return 0;
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}
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/* bit lame of a lookup, but prolly not worth optimizing */
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static int lookup_tree(uint32_t *tree, unsigned int size, uint16_t code, uint8_t len) {
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uint32_t lookup=((uint32_t)(len+1))<<16 | code;
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unsigned int i;
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for(i=0; i<size; i++)
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if(tree[i]==lookup) return i;
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return -1;
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}
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int explode_init(struct xplstate *X, uint16_t flags) {
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X->bits = X->cur = 0;
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if(flags&2) {
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X->largewin = 1;
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X->mask = 0x1fff;
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} else {
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X->largewin = 0;
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X->mask = 0xfff;
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}
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if(flags&4) {
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X->state = GRABLITS;
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X->litcodes = 1;
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X->minlen=3;
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} else {
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X->state = GRABLENS;
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X->litcodes = 0;
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X->minlen=2;
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}
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X->got=0;
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return EXPLODE_OK;
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}
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#define GETBIT \
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if(X->bits) { \
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X->bits--; \
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val=X->bitmap&1; \
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X->bitmap>>=1; \
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} else { \
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if(!X->avail_in) return EXPLODE_EBUFF; \
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if(X->avail_in>=4) { \
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X->bitmap=cli_readint32(X->next_in); \
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X->bits=31; \
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X->next_in+=4; \
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X->avail_in-=4; \
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} else { \
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X->bitmap=*X->next_in; \
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X->bits=7; \
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X->next_in++; \
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X->avail_in--; \
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} \
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val=X->bitmap&1; \
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X->bitmap>>=1; \
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}
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#define GETBITS(NUM) \
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if(X->bits>=(NUM)) { \
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val=X->bitmap&((1<<(NUM))-1); \
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X->bitmap>>=(NUM); \
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X->bits-=(NUM); \
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} else { \
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if(X->avail_in*8+X->bits<(NUM)) return EXPLODE_EBUFF; \
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val=X->bitmap; \
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if(X->avail_in>=4) { \
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X->bitmap=cli_readint32(X->next_in); \
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X->next_in+=4; \
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X->avail_in-=4; \
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val|=(X->bitmap&((1<<((NUM)-X->bits))-1))<<X->bits; \
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X->bitmap>>=(NUM)-X->bits; \
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X->bits=32-((NUM)-X->bits); \
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} else { \
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X->bitmap=*X->next_in; \
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X->next_in++; \
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X->avail_in--; \
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val|=(X->bitmap&((1<<((NUM)-X->bits))-1))<<X->bits; \
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X->bitmap>>=(NUM)-X->bits; \
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X->bits=8-((NUM)-X->bits); \
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} \
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}
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#define GETCODES(CASE, WHICH, HOWMANY) \
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case CASE: { \
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if(!X->avail_in) return EXPLODE_EBUFF; \
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if(!X->got) need = *X->next_in; \
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else need = X->window[0]; \
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if(need > HOWMANY - 1) return EXPLODE_ESTREAM; /* too many codes */ \
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need = need + 2 - X->got; /* bytes remaining */ \
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if(need>X->avail_in) { /* if not enuff */ \
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/* just copy what's avail... */ \
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memcpy(&X->window[X->got], X->next_in, X->avail_in); \
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X->got += X->avail_in; \
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X->next_in += X->avail_in; \
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X->avail_in = 0; \
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return EXPLODE_EBUFF; /* ...and beg for more */ \
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} \
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/* else fetch what's needed */ \
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memcpy(&X->window[X->got], X->next_in, need); \
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X->avail_in -= need; \
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X->next_in += need; \
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if(unpack_tree(X, X->WHICH, HOWMANY )) return EXPLODE_ESTREAM; \
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/* and move on */ \
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X->got=0; \
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X->state++; \
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}
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#define SETCASE(CASE) \
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X->state = (CASE); \
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case(CASE): \
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{/* FAKE */}
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int explode(struct xplstate *X) {
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unsigned int val, need;
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int temp=-1;
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switch(X->state) {
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/* grab compressed coded literals, if present */
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GETCODES(GRABLITS, lit_tree, 256);
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/* grab compressed coded lens */
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GETCODES(GRABLENS, len_tree, 64);
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/* grab compressed coded dists */
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GETCODES(GRABDISTS, dist_tree, 64);
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case EXPLODE:
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while(X->avail_in || X->bits) {
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GETBIT; /* can't fail */
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if(val) {
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if(X->litcodes) {
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X->backsize=0;
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X->state=EXPLODE_LITCODES;
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for(X->got=0; X->got<=15; X->got++) {
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case EXPLODE_LITCODES:
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GETBIT;
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X->backsize|=val<<(15-X->got);
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if((temp=lookup_tree(X->lit_tree, 256, X->backsize, X->got))!=-1) break;
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}
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if(temp==-1) return EXPLODE_ESTREAM;
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X->got=temp;
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} else {
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SETCASE(EXPLODE_LITS);
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GETBITS(8);
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X->got=val;
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}
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SETCASE(EXPLODE_WBYTE);
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if(!X->avail_out) return EXPLODE_EBUFF;
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X->avail_out--;
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*X->next_out = X->window[X->cur & X->mask] = X->got;
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X->cur++;
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X->next_out++;
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} else {
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SETCASE(EXPLODE_BASEDIST);
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GETBITS(6u+X->largewin);
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X->backbytes=val;
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X->backsize=0;
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X->state=EXPLODE_DECODEDISTS;
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for(X->got=0; X->got<=15; X->got++) {
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case EXPLODE_DECODEDISTS:
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GETBIT;
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X->backsize|=val<<(15-X->got);
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if((temp=lookup_tree(X->dist_tree, 64, X->backsize, X->got))!=-1) break;
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}
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if(temp==-1) return EXPLODE_ESTREAM;
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X->backbytes|=temp<<(6+X->largewin);
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X->backbytes++;
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X->backsize=0;
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X->state=EXPLODE_DECODELENS;
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for(X->got=0; X->got<=15; X->got++) {
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case EXPLODE_DECODELENS:
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GETBIT;
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X->backsize|=val<<(15-X->got);
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if((temp=lookup_tree(X->len_tree, 64, X->backsize, X->got))!=-1) break;
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}
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if(temp==-1) return EXPLODE_ESTREAM;
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if(temp==63) {
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SETCASE(EXPLODE_DECODEEXTRA);
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GETBITS(8);
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temp=63+val;
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}
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X->backsize=temp+X->minlen;
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X->state=EXPLODE_BACKCOPY;
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while(X->backsize--) {
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case EXPLODE_BACKCOPY:
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if(!X->avail_out) return EXPLODE_EBUFF;
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X->avail_out--;
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if (X->cur>=X->backbytes)
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*X->next_out = X->window[X->cur & X->mask] = X->window[(X->cur-X->backbytes) & X->mask];
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else
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*X->next_out = X->window[X->cur & X->mask] = 0;
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X->cur++;
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X->next_out++;
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}
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}
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X->state=EXPLODE;
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}
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}
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return EXPLODE_EBUFF;
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}
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void explode_shutdown(void) {}
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