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parsehelper.c
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parsehelper.c
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/*
* -----------------
* VHD Parse helper
* -----------------
* parsehelper.c
* -----------------
* This program takes a vhd file and outputs the sector numbers which don't
* have data stored in them (i.e. they contain metadata).
* ----------------
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*
* Read the README file for the changelog and information on how to
* compile and use this program.
*/
// Global definitions (don't mess with those)
#define _GNU_SOURCE
//#define _LARGEFILE64_SOURCE
#define _FILE_OFFSET_BITS 64
#define MT_PROGNAME "VHD Sherlock"
#define MT_PROGNAME_LEN strlen(MT_PROGNAME)
// Header files
#include <stdio.h> // *printf
#include <stdlib.h> // malloc, free
#include <string.h> // strlen, memset, strncmp, memcpy
#include <unistd.h> // getopt, close, read, lseek
#include <inttypes.h> // PRI*
#include <limits.h>
#include <endian.h> // be*toh
#include <sys/types.h> // *int*_t, open, lseek
#include <sys/stat.h> // open
#include <fcntl.h> // open
// Global definitions
#define MT_CKS 8 // Size of "cookie" entries in headers
#define MT_SECS 512 // Size of a sector
// VHD Footer structure
typedef struct {
u_char cookie[MT_CKS]; // Cookie
u_int32_t features; // Features
u_int32_t ffversion; // File format version
u_int64_t dataoffset; // Data offset
u_int32_t timestamp; // Timestamp
u_int32_t creatorapp; // Creator application
u_int32_t creatorver; // Creator version
u_int32_t creatorhos; // Creator host OS
u_int64_t origsize; // Original size
u_int64_t currsize; // Current size
u_int32_t diskgeom; // Disk geometry
u_int32_t disktype; // Disk type
u_int32_t checksum; // Checksum
u_char uniqueid[16]; // Unique ID
u_char savedst; // Saved state
u_char reserved[427]; // Reserved
}__attribute__((__packed__)) vhd_footer_t;
// VHD Dynamic Disk Header structure
typedef struct {
u_char cookie[MT_CKS]; // Cookie
u_int64_t dataoffset; // Data offset
u_int64_t tableoffset; // Table offset
u_int32_t headerversion; // Header version
u_int32_t maxtabentries; // Max table entries
u_int32_t blocksize; // Block size
u_int32_t checksum; // Checksum
u_char parentuuid[16]; // Parent Unique ID
u_int32_t parentts; // Parent Timestamp
u_char reserved1[4]; // Reserved
u_char parentname[512];// Parent Unicode Name
u_char parentloc1[24]; // Parent Locator Entry 1
u_char parentloc2[24]; // Parent Locator Entry 2
u_char parentloc3[24]; // Parent Locator Entry 3
u_char parentloc4[24]; // Parent Locator Entry 4
u_char parentloc5[24]; // Parent Locator Entry 5
u_char parentloc6[24]; // Parent Locator Entry 6
u_char parentloc7[24]; // Parent Locator Entry 7
u_char parentloc8[24]; // Parent Locator Entry 8
u_char reserved2[256]; // Reserved
}__attribute__((__packed__)) vhd_ddhdr_t;
// Main function
int main(int argc, char **argv){
// Local variables
// VHD File specific
int vhdfd; // VHD file descriptor
vhd_footer_t vhd_footer_copy; // VHD footer copy (beginning of file)
vhd_ddhdr_t vhd_dyndiskhdr; // VHD Dynamic Disk Header
u_int32_t *batmap; // Block allocation table map
vhd_footer_t vhd_footer; // VHD footer (end of file)
// General
int i; // Temporary integers
ssize_t bytesread; // Bytes read in a read operation
off_t offset;
unsigned int smallest;
// Validate there is a filename
if (argc <= 1) {
return(1);
}
// Initialise local variables
memset(&vhd_footer_copy, 0, sizeof(vhd_footer_copy));
memset(&vhd_footer, 0, sizeof(vhd_footer));
// Open VHD file
if ((vhdfd = open(argv[1], O_RDONLY | O_LARGEFILE)) < 0){
perror("open");
fprintf(stderr, "%s: Error opening VHD file \"%s\".\n", argv[0], argv[optind]);
return(1);
}
// little hack to get around a SEEK_SET problem
offset = lseek(vhdfd, -((off_t)sizeof(vhd_footer)), SEEK_END);
// Dump the sector containing the vhd footer
printf("%lld\n", (long long)offset / 512);
if (lseek(vhdfd, offset, SEEK_SET) < 0){
perror("lseek");
fprintf(stderr, "Corrupt disk detected whilst reading VHD footer.\n");
fprintf(stderr, "Error repositioning VHD descriptor to the footer.\n");
close(vhdfd);
return(1);
}
bytesread = read(vhdfd, &vhd_footer, sizeof(vhd_footer));
if (bytesread != sizeof(vhd_footer)){
fprintf(stderr, "Corrupt disk detected whilst reading VHD footer.\n");
close(vhdfd);
return(1);
}
if (strncmp((char *)&(vhd_footer.cookie), "conectix", 8)){
fprintf(stderr, "Corrupt disk detected after reading VHD footer.\n");
fprintf(stderr, "Expected cookie (\"conectix\") missing or corrupt.\n");
close(vhdfd);
return(1);
}
// Check type of disk
switch(be32toh(vhd_footer.disktype)){
case 2:
exit(1);
break;
case 3:
goto dyndisk;
break;
case 4:
goto dyndisk;
break;
default:
exit(1);
break;
}
goto out;
dyndisk:
// Read the VHD footer copy
if (lseek(vhdfd, 0, SEEK_SET) < 0){
perror("lseek");
fprintf(stderr, "Error repositioning VHD descriptor to the file start.\n");
close(vhdfd);
return(1);
}
bytesread = read(vhdfd, &vhd_footer_copy, sizeof(vhd_footer_copy));
if (bytesread != sizeof(vhd_footer_copy)){
fprintf(stderr, "Corrupt disk detected whilst reading VHD footer copy.\n");
close(vhdfd);
return(1);
}
if (strncmp((char *)&(vhd_footer_copy.cookie), "conectix", 8)){
fprintf(stderr, "Corrupt disk detect whilst reading VHD footer copy.\n");
fprintf(stderr, "Expected cookie (\"conectix\") missing or corrupt.\n");
close(vhdfd);
return(1);
}
// Read the VHD dynamic disk header
bytesread = read(vhdfd, &vhd_dyndiskhdr, sizeof(vhd_dyndiskhdr));
if (bytesread != sizeof(vhd_dyndiskhdr)){
fprintf(stderr, "Corrupt disk detected whilst reading VHD Dynamic Disk Header.\n");
close(vhdfd);
return(1);
}
if (strncmp((char *)&(vhd_dyndiskhdr.cookie), "cxsparse", 8)){
fprintf(stderr, "Corrupt disk detect whilst reading Dynamic Disk Header.\n");
fprintf(stderr, "Expected cookie (\"cxsparse\") missing or corrupt.\n");
close(vhdfd);
return(1);
}
// Allocate Batmap
if ((batmap = (u_int32_t *)malloc(sizeof(u_int32_t)*be32toh(vhd_dyndiskhdr.maxtabentries))) == NULL){
perror("malloc");
close(vhdfd);
return(1);
}
// Read batmap
if (lseek(vhdfd, be64toh(vhd_dyndiskhdr.tableoffset), SEEK_SET) < 0){
perror("lseek");
free(batmap);
close(vhdfd);
return(1);
}
bytesread = read(vhdfd, batmap, sizeof(u_int32_t)*be32toh(vhd_dyndiskhdr.maxtabentries));
if (bytesread != sizeof(u_int32_t)*be32toh(vhd_dyndiskhdr.maxtabentries)){
fprintf(stderr, "Error reading batmap.\n");
free(batmap);
close(vhdfd);
return(1);
}
// Dump sector numbers before the first data block. These contain things like
// the footer copy, the dynamic disk header and the batmap.
smallest = UINT_MAX;
for (i=0; i<be32toh(vhd_dyndiskhdr.maxtabentries); i++){
if (batmap[i] == 0xFFFFFFFF){
continue;
}
if (be32toh(batmap[i] < smallest))
smallest = be32toh(batmap[i]);
}
if (smallest != UINT_MAX) {
for (i=0; i < smallest; i++) {
printf("%d\n", i);
}
}
// Dump sector numbers for each block's sector bitmap
for (i=0; i<be32toh(vhd_dyndiskhdr.maxtabentries); i++){
if (batmap[i] == 0xFFFFFFFF){
continue;
}
printf("%u\n", be32toh(batmap[i]));
}
// Free batmap
free(batmap);
out:
// Close file descriptor and return success
close(vhdfd);
return(0);
}