/*
* Copyright (C) 2002 - 2004 Tomasz Kojm <tkojm@clamav.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <string.h>
#include "clamav.h"
#include "others.h"
#include "matcher-ac.h"
#include "matcher-bm.h"
#include "md5.h"
#include "filetypes.h"
#include "matcher.h"
#define MD5_BLOCKSIZE 4096
#define TARGET_TABLE_SIZE 5
static int targettab[TARGET_TABLE_SIZE] = { 0, CL_TYPE_MSEXE, CL_TYPE_MSOLE2, CL_TYPE_HTML, CL_TYPE_MAIL };
int cl_scanbuff(const char *buffer, unsigned int length, const char **virname, const struct cl_node *root)
{
int ret, *partcnt;
unsigned long int *partoff;
if((partcnt = (int *) cli_calloc(root->ac_partsigs + 1, sizeof(int))) == NULL) {
cli_dbgmsg("cl_scanbuff(): unable to cli_calloc(%d, %d)\n", root->ac_partsigs + 1, sizeof(int));
return CL_EMEM;
}
if((partoff = (unsigned long int *) cli_calloc(root->ac_partsigs + 1, sizeof(unsigned long int))) == NULL) {
cli_dbgmsg("cl_scanbuff(): unable to cli_calloc(%d, %d)\n", root->ac_partsigs + 1, sizeof(unsigned long int));
free(partcnt);
return CL_EMEM;
}
if((ret = cli_bm_scanbuff(buffer, length, virname, root, 0, NULL)) != CL_VIRUS)
ret = cli_ac_scanbuff(buffer, length, virname, root, partcnt, 0, 0, partoff, NULL);
free(partcnt);
free(partoff);
return ret;
}
static struct cli_md5_node *cli_vermd5(const unsigned char *md5, const struct cl_node *root)
{
struct cli_md5_node *pt;
if(!(pt = root->md5_hlist[md5[0] & 0xff]))
return NULL;
while(pt) {
if(!memcmp(pt->md5, md5, 16))
return pt;
pt = pt->next;
}
return NULL;
}
int cli_scandesc(int desc, const char **virname, long int *scanned, const struct cl_node *root, short otfrec, unsigned short ftype)
{
char *buffer, *buff, *endbl, *pt;
int bytes, buffsize, length, ret, *partcnt, type = CL_CLEAN;
unsigned long int *partoff, offset = 0;
struct MD5Context ctx;
unsigned char digest[16];
struct cli_md5_node *md5_node;
struct cli_voffset voffset;
if(!root) {
cli_errmsg("cli_scandesc: root == NULL\n");
return CL_ENULLARG;
}
/* prepare the buffer */
buffsize = root->maxpatlen + SCANBUFF;
if(!(buffer = (char *) cli_calloc(buffsize, sizeof(char)))) {
cli_dbgmsg("cli_scandesc(): unable to cli_malloc(%d)\n", buffsize);
return CL_EMEM;
}
if((partcnt = (int *) cli_calloc(root->ac_partsigs + 1, sizeof(int))) == NULL) {
cli_dbgmsg("cli_scandesc(): unable to cli_calloc(%d, %d)\n", root->ac_partsigs + 1, sizeof(int));
free(buffer);
return CL_EMEM;
}
if((partoff = (unsigned long int *) cli_calloc(root->ac_partsigs + 1, sizeof(unsigned long int))) == NULL) {
cli_dbgmsg("cli_scanbuff(): unable to cli_calloc(%d, %d)\n", root->ac_partsigs + 1, sizeof(unsigned long int));
free(buffer);
free(partcnt);
return CL_EMEM;
}
if(root->md5_hlist)
MD5Init(&ctx);
memset(&voffset, 0, sizeof(struct cli_voffset));
buff = buffer;
buff += root->maxpatlen; /* pointer to read data block */
endbl = buff + SCANBUFF - root->maxpatlen; /* pointer to the last block
* length of root->maxpatlen
*/
pt = buff;
length = SCANBUFF;
while((bytes = read(desc, buff, SCANBUFF)) > 0) {
if(scanned)
*scanned += bytes / CL_COUNT_PRECISION;
if(bytes < SCANBUFF)
length -= SCANBUFF - bytes;
if(cli_bm_scanbuff(pt, length, virname, root, offset, &voffset) == CL_VIRUS ||
(ret = cli_ac_scanbuff(pt, length, virname, root, partcnt, otfrec, offset, partoff, &voffset)) == CL_VIRUS) {
free(buffer);
free(partcnt);
free(partoff);
if(voffset.target) {
if(voffset.target >= TARGET_TABLE_SIZE) {
cli_errmsg("Bad target (%d) in signature for %s\n", voffset.target, *virname);
} else if(ftype && ftype != CL_TYPE_UNKNOWN_TEXT) {
if(targettab[voffset.target] != ftype) {
cli_dbgmsg("Expected target type (%d) for %s != %d\n", voffset.target, *virname, ftype);
return CL_CLEAN;
}
} else if(type) {
if(targettab[voffset.target] != type) {
cli_dbgmsg("Expected target type (%d) for %s != %d\n", voffset.target, *virname, type);
return CL_CLEAN;
}
}
}
return CL_VIRUS;
} else if(otfrec && ret >= CL_TYPENO) {
if(ret >= type)
type = ret;
}
if(bytes == SCANBUFF) {
memmove(buffer, endbl, root->maxpatlen);
offset += bytes - root->maxpatlen;
}
pt = buffer;
length = buffsize;
if(root->md5_hlist)
MD5Update(&ctx, buff, bytes);
}
free(buffer);
free(partcnt);
free(partoff);
if(root->md5_hlist) {
MD5Final(digest, &ctx);
if((md5_node = cli_vermd5(digest, root))) {
struct stat sb;
if(fstat(desc, &sb))
return CL_EIO;
if(sb.st_size != md5_node->size) {
cli_warnmsg("Detected false positive MD5 match. Please report.\n");
} else {
if(virname)
*virname = md5_node->virname;
return CL_VIRUS;
}
}
}
return otfrec ? type : CL_CLEAN;
}
int cl_build(struct cl_node *root)
{
return cli_ac_buildtrie(root);
}
void cl_free(struct cl_node *root)
{
int i;
struct cli_md5_node *pt, *h;
if(!root) {
cli_errmsg("cl_free: root == NULL\n");
return;
}
cli_ac_free(root);
cli_bm_free(root);
if(root->md5_hlist) {
for(i = 0; i < 256; i++) {
pt = root->md5_hlist[i];
while(pt) {
h = pt;
pt = pt->next;
free(h->md5);
free(h->virname);
if(h->viralias)
free(h->viralias);
free(h);
}
}
free(root->md5_hlist);
}
free(root);
}
int cl_buildtrie(struct cl_node *root) /* for backward compatibility */
{
return cl_build(root);
}
void cl_freetrie(struct cl_node *root) /* for backward compatibility */
{
cl_free(root);
}