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/*
* headstripper
* File: main.c
* (c) 2019 Jonas Gunz himself(at)jonasgunz.de
*
* License: MIT
* */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <errno.h>
//Magic values
#define _MAGIC_JPG 0xD8FF //JPG Magic Value
#define _MAGIC_PNG 0x5089
#define _MAGIC_PNG_FULL 0x0A1A0A0D474E5089 //89 50 4E 47 0D 0A 1A 0A
#define _MAGIC_TFF 0x2A00 //TIFF Magic Value
//JPG
#define _JPG_EXIF 0xE1 //EXIF
#define _JPG_COM 0xFE //Comments
#define _JPG_COPY 0xEE //Copyright notice
#define _JPG_SOS 0xDA //Start of image data
#define _JPG_EOI 0xD9 //End of image
//PNG
#define _PNG_IHDR 0x52444849
#define _PNG_IDAT 0x54414449
#define _PNG_IEND 0x444E4549
#define _PNG_PLTE 0x45544C50
int strip_jpg(char *_filename);
int strip_png(char *_filename);
int strip_tiff(char *_filename);
int main(int argc, char* argv[])
{
FILE *image;
uint16_t magic;
if(argc != 2)
{
printf("Wrong number of arguments!\nUsage: %s <Filename>\n", argv[0]);
exit(1);
}
//Read magic val
image = fopen(argv[1], "r");
if(!image)
{
printf("Unable to open \"%s\": %i\n", argv[1], errno);
exit(2);
}
fread(&magic, 2, 1, image);
fclose(image);
switch(magic)
{
case _MAGIC_JPG:
printf("Detected JPG\n");
strip_jpg(argv[1]);
break;
case _MAGIC_PNG:
printf("Detected PNG\n");
strip_png(argv[1]);
break;
case _MAGIC_TFF:
printf("Detected TIFF\n");
strip_tiff(argv[1]);
break;
default:
printf("Bad/Unknown Filetype\n");
exit(1);
break;
};
return 0;
}
//This function assumes a valid JFIF container file! No file validation is performed
int strip_jpg(char *_filename)
{
FILE *in;
FILE *out;
int f__outfile_len = strlen(_filename);
char *f__outfile = malloc(f__outfile_len + 8);
strcpy( f__outfile, _filename);
strcpy(&f__outfile[f__outfile_len], ".strip\0");
in = fopen(_filename, "r");
out = fopen(f__outfile, "w");
//Feelin' lazy. Might add debug later, idk
if(!in)
return 1;
if(!out) {
printf("Unable to open for writing %s: %i\n", f__outfile, errno);
return 1;
}
while(1)
{
unsigned char c = fgetc(in);
if(c == 0xFF)
{
unsigned char c2 = fgetc(in);
if( c2 == _JPG_EXIF || c2 == _JPG_COM || c2 == _JPG_COPY ) //Add tags here
{
unsigned char c3 = fgetc(in);
unsigned char c4 = fgetc(in);
uint16_t seg_len = (( c3 << 8 ) & 0xff00) + c4;
printf("SEG %X SEGLEN %uB\n", c2, seg_len);
seg_len -= 2; //2B are already read!
for (uint16_t i = 0; i < seg_len; i++) {
fgetc(in);
}
}
else if ( c2 == _JPG_EOI )
{
printf("ENDSEG\n");
fputc(c, out);
fputc(c2, out);
break;
}
else
{
fputc(c, out);
fputc(c2, out);
}
}
else
fputc(c, out);
if(feof(in))
break;
}
fclose(in);
fclose(out);
free(f__outfile);
return 0;
}
int strip_png(char *_filename)
{
FILE *in;
FILE *out;
int f__outfile_len = strlen(_filename);
char *f__outfile = malloc(f__outfile_len + 8);
strcpy( f__outfile, _filename);
strcpy(&f__outfile[f__outfile_len], ".strip\0");
in = fopen(_filename, "r");
out = fopen(f__outfile, "w");
if(!in)
return 1;
if(!out) {
printf("Unable to open for writing %s: %i\n", f__outfile, errno);
return 1;
}
uint64_t magic_num = _MAGIC_PNG_FULL;
fwrite(&magic_num, 1, 8, out);
uint32_t read_buff = 0;
uint32_t chunk_len = 0;
while(1)
{
//Heavy shifting
//Chunk header is 4B
chunk_len = ((chunk_len << 8) & 0xFFFFFF00) + ( read_buff & 0x000000FF );
unsigned char c = fgetc(in);
read_buff = ((read_buff >> 8) & 0x00FFFFFF) + (((uint32_t)c << 24) & 0xFF000000);
//Whitelist only important PNG chunks
if( read_buff == _PNG_IHDR ||
read_buff == _PNG_IDAT ||
read_buff == _PNG_PLTE ||
read_buff == _PNG_IEND )
{
char *f__buffer = malloc( chunk_len );
uint32_t crc;
//*Ghetto music plays*
uint64_t chunk_str = 0;
chunk_str += read_buff;
printf("CHUNK %s SIZE %uB\n", &chunk_str, chunk_len);
fread(f__buffer, 1, chunk_len, in);
fread(&crc, 1, 4, in);
fwrite(&chunk_len, 1, sizeof(chunk_len), out);
fwrite(&read_buff, 1, sizeof(read_buff), out);
fwrite(f__buffer, 1, chunk_len, out);
fwrite(&crc, 1, 4, out);
free(f__buffer);
if(read_buff == _PNG_IEND)
break;
}
if(feof(in))
break;
}
fclose(in);
fclose(out);
free(f__outfile);
return 1;
}
int strip_tiff(char *_filename)
{
FILE *in;
FILE *out;
int f__outfile_len = strlen(_filename);
char *f__outfile = malloc(f__outfile_len + 8);
strcpy( f__outfile, _filename);
strcpy(&f__outfile[f__outfile_len], ".strip\0");
in = fopen(_filename, "r");
out = fopen(f__outfile, "w");
if(!in)
return 1;
if(!out) {
printf("Unable to open for writing %s: %i\n", f__outfile, errno);
return 1;
}
printf("Unimplemented\n");
fclose(in);
fclose(out);
free(f__outfile);
return 1;
}
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