/*

  *  Copyright (C) 2002 - 2006 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., 51 Franklin Street, Fifth Floor, Boston,
  *  MA 02110-1301, USA.

  */
 

 #if HAVE_CONFIG_H
 #include "clamav-config.h"
 #endif
 

 #include <string.h>

 #include <ctype.h>
 #include <sys/types.h>
 #include <sys/stat.h>

 #ifdef	HAVE_UNISTD_H

 #include <unistd.h>

 #endif

 
 #include "clamav.h"
 #include "others.h"

 #include "matcher-ac.h"
 #include "matcher-bm.h"
 #include "md5.h"

 #include "filetypes.h"

 #include "matcher.h"

 #include "pe.h"

 #include "elf.h"
 #include "execs.h"

 #include "special.h"

 #include "str.h"

 #ifdef HAVE_NCORE

 #include "matcher-ncore.h"

 #endif
 

 static cli_file_t targettab[CL_TARGET_TABLE_SIZE] = { 0, CL_TYPE_MSEXE, CL_TYPE_MSOLE2, CL_TYPE_HTML, CL_TYPE_MAIL, CL_TYPE_GRAPHICS, CL_TYPE_ELF };

 
 extern short cli_debug_flag;

 int cli_scanbuff(const unsigned char *buffer, unsigned int length, const char **virname, const struct cl_engine *engine, cli_file_t ftype)

 {

 	int ret = CL_CLEAN, i;

 	struct cli_ac_data mdata;

 	struct cli_matcher *groot, *troot = NULL;

     if(!engine) {
 	cli_errmsg("cli_scanbuff: engine == NULL\n");
 	return CL_ENULLARG;
     }
 

 #ifdef HAVE_NCORE

     if(engine->ncore)
 	return cli_ncore_scanbuff(buffer, length, virname, engine, ftype, targettab);
 #endif

     groot = engine->root[0]; /* generic signatures */
 
     if(ftype) {

 	for(i = 1; i < CL_TARGET_TABLE_SIZE; i++) {

 	    if(targettab[i] == ftype) {

 		troot = engine->root[i];

 		break;
 	    }
 	}
     }
 
     if(troot) {
 

 	if((ret = cli_ac_initdata(&mdata, troot->ac_partsigs, AC_DEFAULT_TRACKLEN)))
 	    return ret;

 	if(troot->ac_only || (ret = cli_bm_scanbuff(buffer, length, virname, troot, 0, ftype, -1)) != CL_VIRUS)

 	    ret = cli_ac_scanbuff(buffer, length, virname, troot, &mdata, 0, 0, ftype, -1, NULL);

 	cli_ac_freedata(&mdata);

 
 	if(ret == CL_VIRUS)
 	    return ret;
     }
 

     if((ret = cli_ac_initdata(&mdata, groot->ac_partsigs, AC_DEFAULT_TRACKLEN)))
 	return ret;

     if(groot->ac_only || (ret = cli_bm_scanbuff(buffer, length, virname, groot, 0, ftype, -1)) != CL_VIRUS)

 	ret = cli_ac_scanbuff(buffer, length, virname, groot, &mdata, 0, 0, ftype, -1, NULL);
 
     cli_ac_freedata(&mdata);

 
     return ret;

 }
 

 struct cli_md5_node *cli_vermd5(const unsigned char *md5, const struct cl_engine *engine)

 {

 	struct cli_md5_node *pt;

     if(!(pt = engine->md5_hlist[md5[0] & 0xff]))

 	return NULL;
 

     while(pt) {
 	if(!memcmp(pt->md5, md5, 16))
 	    return pt;

 	pt = pt->next;

     }

     return NULL;

 }
 

 off_t cli_caloff(const char *offstr, struct cli_target_info *info, int fd, cli_file_t ftype, int *ret)

 {

 	int (*einfo)(int, struct cli_exe_info *) = NULL;

 	unsigned int n;
 	off_t pos, offset;

     *ret = 0;
 
     if(!strncmp(offstr, "EP", 2) || offstr[0] == 'S') {
 
 	if(info->status == -1) {
 	    *ret = -1;
 	    return 0;
 
 	} else if(!info->status) {
 
 	    if(ftype == CL_TYPE_MSEXE)
 		einfo = cli_peheader;
 	    else if(ftype == CL_TYPE_ELF)
 		einfo = cli_elfheader;
 
 	    if(einfo) {
 		if((pos = lseek(fd, 0, SEEK_CUR)) == -1) {
 		    cli_dbgmsg("Invalid descriptor\n");
 		    info->status = *ret = -1;
 		    return 0;
 		}
 
 		lseek(fd, 0, SEEK_SET);
 		if(einfo(fd, &info->exeinfo)) {
 		    lseek(fd, pos, SEEK_SET);
 		    info->status = *ret = -1;
 		    return 0;
 		}
 		lseek(fd, pos, SEEK_SET);
 		info->status = 1;
 	    }
 	}
     }

     if(isdigit(offstr[0])) {
 	return atoi(offstr);

     } else if(info->status == 1 && (!strncmp(offstr, "EP+", 3) || !strncmp(offstr, "EP-", 3))) {

 
 	if(offstr[2] == '+')

 	    return info->exeinfo.ep + atoi(offstr + 3);

 	else

 	    return info->exeinfo.ep - atoi(offstr + 3);

     } else if(info->status == 1 && offstr[0] == 'S') {

 	if(!strncmp(offstr, "SL", 2) && info->exeinfo.section[info->exeinfo.nsections - 1].rsz) {

 	    if(sscanf(offstr, "SL+%lu", &offset) != 1) {
 		*ret = -1;
 		return 0;

 	    }
 

 	    offset += info->exeinfo.section[info->exeinfo.nsections - 1].raw;

 
 	} else {
 

 	    if(sscanf(offstr, "S%u+%lu", &n, &offset) != 2) {
 		*ret = -1;
 		return 0;

 	    }
 

 	    if(n >= info->exeinfo.nsections || !info->exeinfo.section[n].rsz) {

 		*ret = -1;
 		return 0;

 	    }
 

 	    offset += info->exeinfo.section[n].raw;

 	}
 
 	return offset;

     } else if(!strncmp(offstr, "EOF-", 4)) {
 	    struct stat sb;
 

 	if(!info->fsize) {
 	    if(fstat(fd, &sb) == -1) {
 		info->status = *ret = -1;
 		return 0;
 	    }
 	    info->fsize = sb.st_size;
 	}

 	return info->fsize - atoi(offstr + 4);

     }
 

     *ret = -1;
     return 0;

 }
 

 static int cli_checkfp(int fd, const struct cl_engine *engine)

 {
 	struct cli_md5_node *md5_node;

 	unsigned char *digest;

     if(engine->md5_hlist) {

 
 	if(!(digest = cli_md5digest(fd))) {
 	    cli_errmsg("cli_checkfp(): Can't generate MD5 checksum\n");
 	    return 0;
 	}
 

 	if((md5_node = cli_vermd5(digest, engine)) && md5_node->fp) {

 		struct stat sb;
 
 	    if(fstat(fd, &sb))
 		return CL_EIO;
 

 	    if((unsigned int) sb.st_size != md5_node->size) {

 		cli_warnmsg("Detected false positive MD5 match. Please report.\n");
 	    } else {
 		cli_dbgmsg("Eliminated false positive match (fp sig: %s)\n", md5_node->virname);
 		free(digest);
 		return 1;
 	    }
 	}
 
 	free(digest);
     }
 
     return 0;
 }
 

 int cli_validatesig(cli_file_t ftype, const char *offstr, off_t fileoff, struct cli_target_info *info, int desc, const char *virname)

 {

 	off_t offset;
 	int ret;
 

 
     if(offstr && desc != -1) {

 	offset = cli_caloff(offstr, info, desc, ftype, &ret);

 	if(ret == -1) {
 	    cli_dbgmsg("cli_validatesig: Can't calculate offset for signature %s\n", virname);

 	    return 0;
 	}
 

 	if(fileoff != offset) {
 	    cli_dbgmsg("Signature offset: %lu, expected: %lu (%s)\n", fileoff, offset, virname);

 	    return 0;
 	}
     }
 
     return 1;
 }
 

 int cli_scandesc(int desc, cli_ctx *ctx, unsigned short otfrec, cli_file_t ftype, unsigned short ftonly, struct cli_matched_type **ftoffset)

 {

  	unsigned char *buffer, *buff, *endbl, *upt;

 	int ret = CL_CLEAN, type = CL_CLEAN, i, bytes;

 	unsigned int buffersize, length, maxpatlen, shift = 0;

 	unsigned long int offset = 0;
 	struct cli_ac_data gdata, tdata;

 	MD5_CTX md5ctx;

 	unsigned char digest[16];

 	struct cli_md5_node *md5_node;

 	struct cli_matcher *groot = NULL, *troot = NULL;

     if(!ctx->engine) {

 	cli_errmsg("cli_scandesc: engine == NULL\n");

 	return CL_ENULLARG;

     }
 

 #ifdef HAVE_NCORE
     if(ctx->engine->ncore) {

 	    int cont;

 	ret = cli_ncore_scandesc(desc, ctx, ftype, &cont, targettab, &md5ctx);
 	if(!cont)

 	    return ret;

     }

 #endif

     if(!ftonly)
 	groot = ctx->engine->root[0]; /* generic signatures */

 
     if(ftype) {

 	for(i = 1; i < CL_TARGET_TABLE_SIZE; i++) {

 	    if(targettab[i] == ftype) {

 		troot = ctx->engine->root[i];

 		break;
 	    }
 	}
     }
 

     if(ftonly) {
 	if(!troot)
 	    return CL_CLEAN;
 
 	maxpatlen = troot->maxpatlen;
     } else {
 	if(troot)
 	    maxpatlen = MAX(troot->maxpatlen, groot->maxpatlen);
 	else
 	    maxpatlen = groot->maxpatlen;
     }

     /* prepare the buffer */

     buffersize = maxpatlen + SCANBUFF;

     if(!(buffer = (unsigned char *) cli_calloc(buffersize, sizeof(unsigned char)))) {

 	cli_dbgmsg("cli_scandesc(): unable to cli_calloc(%u)\n", buffersize);

 	return CL_EMEM;
     }

     if(!ftonly && (ret = cli_ac_initdata(&gdata, groot->ac_partsigs, AC_DEFAULT_TRACKLEN)))

 	return ret;

     if(troot) {

 	if((ret = cli_ac_initdata(&tdata, troot->ac_partsigs, AC_DEFAULT_TRACKLEN)))
 	    return ret;

     }
 

     if(!ftonly && ctx->engine->md5_hlist)

 	MD5_Init(&md5ctx);

     buff = buffer;

     buff += maxpatlen; /* pointer to read data block */
     endbl = buff + SCANBUFF - maxpatlen; /* pointer to the last block

 					  * length of maxpatlen
 					  */

     upt = buff;

     while((bytes = cli_readn(desc, buff + shift, SCANBUFF - shift)) > 0) {

 	if(ctx->scanned)
 	    *ctx->scanned += bytes / CL_COUNT_PRECISION;

 	length = shift + bytes;

 	if(upt == buffer)

 	    length += maxpatlen;

 	if(troot) {

 	    if(troot->ac_only || (ret = cli_bm_scanbuff(upt, length, ctx->virname, troot, offset, ftype, desc)) != CL_VIRUS)
 		ret = cli_ac_scanbuff(upt, length, ctx->virname, troot, &tdata, otfrec, offset, ftype, desc, ftoffset);

 
 	    if(ret == CL_VIRUS) {

 		free(buffer);

 		if(!ftonly)
 		    cli_ac_freedata(&gdata);

 		cli_ac_freedata(&tdata);

 
 		lseek(desc, 0, SEEK_SET);

 		if(cli_checkfp(desc, ctx->engine))

 		    return CL_CLEAN;
 		else
 		    return CL_VIRUS;
 	    }
 	}

 	if(!ftonly) {
 	    if(groot->ac_only || (ret = cli_bm_scanbuff(upt, length, ctx->virname, groot, offset, ftype, desc)) != CL_VIRUS)
 		ret = cli_ac_scanbuff(upt, length, ctx->virname, groot, &gdata, otfrec, offset, ftype, desc, ftoffset);

 	    if(ret == CL_VIRUS) {
 		free(buffer);
 		cli_ac_freedata(&gdata);
 		if(troot)
 		    cli_ac_freedata(&tdata);
 		lseek(desc, 0, SEEK_SET);
 		if(cli_checkfp(desc, ctx->engine))
 		    return CL_CLEAN;
 		else
 		    return CL_VIRUS;

 	    } else if(otfrec && ret >= CL_TYPENO) {
 		if(ret > type)
 		    type = ret;
 	    }

 	    if(ctx->engine->md5_hlist)
 		MD5_Update(&md5ctx, buff + shift, bytes);
 	}

 
 	if(bytes + shift == SCANBUFF) {

 	    memmove(buffer, endbl, maxpatlen);

 	    offset += SCANBUFF;

 	    if(upt == buff) {
 		upt = buffer;

 		offset -= maxpatlen;

 	    }

 
 	    shift = 0;
 
 	} else {
 	    shift += bytes;

 	}

     }

     free(buffer);

     if(!ftonly)
 	cli_ac_freedata(&gdata);

     if(troot)
 	cli_ac_freedata(&tdata);

     if(!ftonly && ctx->engine->md5_hlist) {

 	MD5_Final(digest, &md5ctx);

 	if((md5_node = cli_vermd5(digest, ctx->engine)) && !md5_node->fp) {

 		struct stat sb;
 
 	    if(fstat(desc, &sb))
 		return CL_EIO;
 

 	    if((unsigned int) sb.st_size != md5_node->size) {

 		cli_warnmsg("Detected false positive MD5 match. Please report.\n");
 	    } else {

 		if(ctx->virname)
 		    *ctx->virname = md5_node->virname;

 
 		return CL_VIRUS;
 	    }

 	}

     }
 

     return otfrec ? type : CL_CLEAN;

 }