/*
  *  Copyright (C) 2004 Tomasz Kojm <tkojm@clamav.net>
  *
  *  Implementation (header structures) based on the PE format description
  *  by B. Luevelsmeyer
  *
  *  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 <stdio.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <unistd.h>
 #include <time.h>
 
 #include "cltypes.h"
 #include "clamav.h"
 #include "others.h"
 
 #define IMAGE_DOS_SIGNATURE	    0x5a4d	    /* MZ */
 #define IMAGE_NT_SIGNATURE	    0x00004550
 #define IMAGE_OPTIONAL_SIGNATURE    0x010b
 
 struct pe_image_file_hdr {
     uint32_t Magic;
     uint16_t Machine;
     uint16_t NumberOfSections;
     uint32_t TimeDateStamp;		    /* unreliable */
     uint32_t PointerToSymbolTable;	    /* debug */
     uint32_t NumberOfSymbols;		    /* debug */
     uint16_t SizeOfOptionalHeader;	    /* == 224 */
     uint16_t Characteristics;
 };
 
 struct pe_image_data_dir {
     uint32_t VirtualAddress;
     uint32_t Size;
 };
 
 struct pe_image_optional_hdr {
     uint16_t Magic;
     uint8_t  MajorLinkerVersion;		    /* unreliable */
     uint8_t  MinorLinkerVersion;		    /* unreliable */
     uint32_t SizeOfCode;			    /* unreliable */
     uint32_t SizeOfInitializedData;		    /* unreliable */
     uint32_t SizeOfUninitializedData;		    /* unreliable */
     uint32_t AddressOfEntryPoint;
     uint32_t BaseOfCode;
     uint32_t BaseOfData;
     uint32_t ImageBase;				    /* multiple of 64 KB */
     uint32_t SectionAlignment;			    /* usually 32 or 4096 */
     uint32_t FileAlignment;			    /* usually 32 or 512 */
     uint16_t MajorOperatingSystemVersion;	    /* not used */
     uint16_t MinorOperatingSystemVersion;	    /* not used */
     uint16_t MajorImageVersion;			    /* unreliable */
     uint16_t MinorImageVersion;			    /* unreliable */
     uint16_t MajorSubsystemVersion;
     uint16_t MinorSubsystemVersion;
     uint32_t Win32VersionValue;			    /* ? */
     uint32_t SizeOfImage;
     uint32_t SizeOfHeaders;
     uint32_t CheckSum;				    /* NT drivers only */
     uint16_t Subsystem;
     uint16_t DllCharacteristics;
     uint32_t SizeOfStackReserve;
     uint32_t SizeOfStackCommit;
     uint32_t SizeOfHeapReserve;
     uint32_t SizeOfHeapCommit;
     uint32_t LoaderFlags;			    /* ? */
     uint32_t NumberOfRvaAndSizes;		    /* unreliable */
     struct pe_image_data_dir DataDirectory[16];
 };
 
 struct pe_image_section_hdr {
     uint8_t Name[8];			    /* may not end with NULL */
     /*
     union {
 	uint32_t PhysicalAddress;
 	uint32_t VirtualSize;
     } AddrSize;
     */
     uint32_t VirtualSize;
     uint32_t VirtualAddress;
     uint32_t SizeOfRawData;		    /* multiple of FileAlignment */
     uint32_t PointerToRawData;		    /* offset to the section's data */
     uint32_t PointerToRelocations;	    /* object files only */
     uint32_t PointerToLinenumbers;	    /* object files only */
     uint16_t NumberOfRelocations;	    /* object files only */
     uint16_t NumberOfLinenumbers;	    /* object files only */
     uint32_t Characteristics;
 };
 

 int ddump(int desc, int offset, int size, const char *file)
 {
 	int pos, ndesc, bread, sum = 0;
 	char buff[FILEBUFF];
 
 
     cli_dbgmsg("in ddump()\n");
 
     if((pos = lseek(desc, 0, SEEK_CUR)) == -1) {
 	cli_dbgmsg("Invalid descriptor\n");
 	return -1;
     }
 
     if(lseek(desc, offset, SEEK_SET) == -1) {
 	cli_dbgmsg("lseek() failed\n");
 	lseek(desc, pos, SEEK_SET);
 	return -1;
     }
 
     if((ndesc = open(file, O_WRONLY|O_CREAT|O_TRUNC, S_IRWXU)) < 0) {
 	cli_dbgmsg("Can't create file %s\n", file);
 	lseek(desc, pos, SEEK_SET);
 	return -1;
     }
 
     while((bread = read(desc, buff, FILEBUFF)) > 0) {
 	if(sum + bread >= size) {
 	    if(write(ndesc, buff, size - sum) == -1) {
 		cli_dbgmsg("Can't write to file\n");
 		lseek(desc, pos, SEEK_SET);
 		close(ndesc);
 		unlink(file);
 		return -1;
 	    }
 	    break;
 	} else {
 	    if(write(ndesc, buff, bread) == -1) {
 		cli_dbgmsg("Can't write to file\n");
 		lseek(desc, pos, SEEK_SET);
 		close(ndesc);
 		unlink(file);
 		return -1;
 	    }
 	}
 	sum += bread;
     }
 
     close(ndesc);
     lseek(desc, pos, SEEK_SET);
     return 0;
 }
 

 int cli_scanpe(int desc, const char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *reclev)
 {
 	uint16_t e_magic; /* DOS signature ("MZ") */
 	uint32_t e_lfanew; /* address of new exe header */
 	struct pe_image_file_hdr file_hdr;
 	struct pe_image_optional_hdr optional_hdr;
 	struct pe_image_section_hdr section_hdr;
 	struct stat sb;
 	char sname[9];
 	int i;
 
 
     if(read(desc, &e_magic, sizeof(e_magic)) != sizeof(e_magic)) {

 	cli_dbgmsg("Can't read DOS signature\n");

 	return -1;
     }
 
     if(e_magic != IMAGE_DOS_SIGNATURE) {
 	cli_dbgmsg("Invalid DOS signature\n");
 	return -1;
     }
 
     lseek(desc, 58, SEEK_CUR); /* skip to the end of the DOS header */
 
     if(read(desc, &e_lfanew, sizeof(e_lfanew)) != sizeof(e_lfanew)) {

 	cli_dbgmsg("Can't read new header address\n");

 	return -1;
     }
 
     cli_dbgmsg("e_lfanew == %d\n", e_lfanew);
     if(!e_lfanew) {
 	cli_dbgmsg("Not a PE file\n");
 	return -2;
     }
 
     lseek(desc, e_lfanew, SEEK_SET);
 
     if(read(desc, &file_hdr, sizeof(struct pe_image_file_hdr)) != sizeof(struct pe_image_file_hdr)) {
 	cli_dbgmsg("Can't read file header\n");
 	return -1;
     }
 
     if(file_hdr.Magic != IMAGE_NT_SIGNATURE) {

 	cli_dbgmsg("Invalid PE signature (probably NE file)\n");

 	return -2;
     }
 

     /* cli_dbgmsg("Machine type: "); */

     switch(file_hdr.Machine) {
 	case 0x14c:

 	    cli_dbgmsg("Machine type: 80386\n");

 	    break;
 	case 0x014d:

 	    cli_dbgmsg("Machine type: 80486\n");

 	    break;
 	case 0x014e:

 	    cli_dbgmsg("Machine type: 80586\n");

 	    break;
 	case 0x162:

 	    cli_dbgmsg("Machine type: R3000\n");

 	    break;
 	case 0x166:

 	    cli_dbgmsg("Machine type: R4000\n");

 	    break;
 	case 0x168:

 	    cli_dbgmsg("Machine type: R10000\n");

 	    break;
 	case 0x184:

 	    cli_dbgmsg("Machine type: DEC Alpha AXP\n");

 	    break;
 	case 0x1f0:

 	    cli_dbgmsg("Machine type: PowerPC\n");

 	    break;
 	default:

 	    cli_warnmsg("Unknown machine type in PE header\n");

     }
 
     cli_dbgmsg("NumberOfSections: %d\n", file_hdr.NumberOfSections);
     cli_dbgmsg("TimeDateStamp: %s", ctime((time_t *) &file_hdr.TimeDateStamp));
 
     cli_dbgmsg("SizeOfOptionalHeader: %d\n", file_hdr.SizeOfOptionalHeader);
 
     if(file_hdr.SizeOfOptionalHeader != sizeof(struct pe_image_optional_hdr)) {
 	cli_warnmsg("Broken PE header detected.\n");
 	return -1;
     }
 
     if(read(desc, &optional_hdr, sizeof(struct pe_image_optional_hdr)) != sizeof(struct pe_image_optional_hdr)) {
 	cli_dbgmsg("Can't optional file header\n");
 	return -1;
     }
 
     cli_dbgmsg("MajorLinkerVersion: %d\n", optional_hdr.MajorLinkerVersion);
     cli_dbgmsg("MinorLinkerVersion: %d\n", optional_hdr.MinorLinkerVersion);
     cli_dbgmsg("SizeOfCode: %d\n", optional_hdr.SizeOfCode);
     cli_dbgmsg("SizeOfInitializedData: %d\n", optional_hdr.SizeOfInitializedData);
     cli_dbgmsg("SizeOfUninitializedData: %d\n", optional_hdr.SizeOfUninitializedData);
     cli_dbgmsg("AddressOfEntryPoint: 0x%x\n", optional_hdr.AddressOfEntryPoint);
     cli_dbgmsg("SectionAlignment: %d\n", optional_hdr.SectionAlignment);
     cli_dbgmsg("FileAlignment: %d\n", optional_hdr.FileAlignment);
     cli_dbgmsg("MajorSubsystemVersion: %d\n", optional_hdr.MajorSubsystemVersion);
     cli_dbgmsg("MinorSubsystemVersion: %d\n", optional_hdr.MinorSubsystemVersion);
     cli_dbgmsg("SizeOfImage: %d\n", optional_hdr.SizeOfImage);
     cli_dbgmsg("SizeOfHeaders: %d\n", optional_hdr.SizeOfHeaders);
 
     switch(optional_hdr.Subsystem) {
 	case 1:

 	    cli_dbgmsg("Subsystem: Native (a driver ?)\n");

 	    break;
 	case 2:

 	    cli_dbgmsg("Subsystem: Win32 GUI\n");

 	    break;
 	case 3:

 	    cli_dbgmsg("Subsystem: Win32 console\n");

 	    break;
 	case 5:

 	    cli_dbgmsg("Subsystem: OS/2 console\n");

 	    break;
 	case 7:

 	    cli_dbgmsg("Subsystem: POSIX console\n");

 	    break;
 	default:

 	    cli_warnmsg("Unknown subsystem in PE header\n");

     }
 
     cli_dbgmsg("NumberOfRvaAndSizes: %d\n", optional_hdr.NumberOfRvaAndSizes);
 
     for(i = 0; i < file_hdr.NumberOfSections; i++) {
 
 	if(read(desc, &section_hdr, sizeof(struct pe_image_section_hdr)) != sizeof(struct pe_image_section_hdr)) {
 	    cli_dbgmsg("Can't read section header\n");
 	    return -1;
 	}
 
 	strncpy(sname, section_hdr.Name, 8);
 	sname[8] = 0;
 	cli_dbgmsg("------------------------------------\n");
 	cli_dbgmsg("Section name: %s\n", sname);
 	cli_dbgmsg("VirtualSize: %d\n", section_hdr.VirtualSize);
 	cli_dbgmsg("VirtualAddress: 0x%x\n", section_hdr.VirtualAddress);
 	cli_dbgmsg("Section size: %d\n", section_hdr.SizeOfRawData);
 	cli_dbgmsg("PointerToRawData: 0x%x (%d)\n", section_hdr.PointerToRawData, section_hdr.PointerToRawData);
 

 	if(section_hdr.Characteristics & 0x20) {
 	    cli_dbgmsg("Section contains executable code\n");
 
 	    if(section_hdr.VirtualSize < section_hdr.SizeOfRawData) {
 		cli_dbgmsg("Section contains free space\n");
 		/*
 		cli_dbgmsg("Dumping %d bytes\n", section_hdr.SizeOfRawData - section_hdr.VirtualSize);
 		ddump(desc, section_hdr.PointerToRawData + section_hdr.VirtualSize, section_hdr.SizeOfRawData - section_hdr.VirtualSize, cl_gentemp(NULL));
 		*/
 
 	    }
 	}

 
 	if(section_hdr.Characteristics & 0x20000000)

 	    cli_dbgmsg("Section's memory is executable\n");
 
 /*
 	if(!strcmp(sname, "_winzip_")) {
 	    int ptrd = section_hdr.PointerToRawData & ~(optional_hdr.FileAlignment - 1);
 
 	    cli_dbgmsg("WinZip section\n");
 	    ddump(desc, ptrd, section_hdr.SizeOfRawData, cl_gentemp(NULL));
 	}
 */
 

     }
 
     if(fstat(desc, &sb) == -1) {

 	cli_dbgmsg("fstat failed\n");

 	return -1;
     }
 
     if(section_hdr.PointerToRawData + section_hdr.SizeOfRawData > sb.st_size) {
 	cli_warnmsg("Possibly broken PE file\n");
 	return -1;
     }
 
     /* to be continued ... */
 
     return 0;
 }