1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
|
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
void extract_contained_binary(){
double bin_hex_div = (double)strlen((const char*)BIN_HEX) / 2;
if ( bin_hex_div == 0.5 ){
fputs( "Error: binary hex is uneven number of characters\n", stderr );
return;
}
size_t hex_byte_count = (size_t)bin_hex_div;
unsigned char *decoded_bytes = (unsigned char*)calloc( hex_byte_count + 1, sizeof(unsigned char) );
if ( decoded_bytes == NULL ){
fprintf( stderr, "Error: failed to allocate memory for decoding: %s\n", strerror(errno) );
return;
}
const char *bin_hex = (const char*)BIN_HEX;
size_t byte_pos = 0;
size_t dec_byte_pos = 0;
char c_byte[2];
memset( (void*)&c_byte, 0, sizeof(c_byte) );
unsigned char decoded_byte = '\0';
for ( ; dec_byte_pos < hex_byte_count; byte_pos += 2, dec_byte_pos++ ){
memmove( (void*)&c_byte, (const void*)&bin_hex[byte_pos], 2 );
decoded_byte = (unsigned char)strtoul( (const char*)&c_byte, NULL, 16 );
if ( errno != 0 ){
fprintf( stderr, "Error: failed to decode byte: %s\n", strerror(errno) );
free( decoded_bytes );
return;
}
decoded_bytes[dec_byte_pos] = decoded_byte;
}
int out_fd = open( "/tmp/test_output_binary", O_RDWR | O_CREAT, 0755 );
if ( out_fd == -1 ){
fprintf( stderr, "Error: failed to open /tmp/test_output_binary for writing: %s\n", strerror(errno) );
free( decoded_bytes );
return;
}
if ( write(out_fd, (const void*)decoded_bytes, hex_byte_count + 1) == -1 ){
fprintf( stderr, "Error: failed to write /tmp/test_output_binary: %s\n", strerror(errno) );
free( decoded_bytes );
close( out_fd );
return;
}
close( out_fd );
free( decoded_bytes );
fputs( "Binary extracted, check /tmp for test_output_binary\n", stdout );
return;
}
int main( int argc, char *const *args ){
extract_contained_binary();
return 0;
}
|
