Initial PNG CC Implementation

Signed-off-by: Pin <wf6DJd8a3xSSCZbn@protonmail.com>

.gitignore

@@ -2,4 +2,6 @@
 *.out
 *.woo
 *.wow
+*.gch
+vgcore.*
 bin/

Makefile

@@ -14,3 +14,6 @@ output_dir:
 
 clean:
 	rm -rf $(OUTPUT_DIR) **.h.gch
+
+memcheck: debug
+	valgrind --tool=memcheck --leak-check=yes --show-reachable=yes --num-callers=20 --track-fds=yes -s ${OUTPUT_DIR}/crc

cmd/crc.c

@@ -1,8 +1,12 @@
+#pragma GCC optimize("Ofast")
+
+#include <endian.h>
 #include <stdio.h>
 #include <unistd.h>
 #include <string.h>
 #include <stdlib.h>
 #include <sodium.h>
+#include <getopt.h>
 #include "crc_util.h"
 #include "CRCLib.h"
 #include "crc.h"
@@ -66,8 +70,6 @@ void random_data_change(unsigned char *color_data, int width, int length) {
 	int color_range = 3;	
 	unsigned char temp_color_data[length];
 
-	memcpy(temp_color_data, color_data, length);
-
 	do {
 		rounds++;
 		// Creating temporary data set
@@ -96,6 +98,7 @@ void random_data_change(unsigned char *color_data, int width, int length) {
 			unsigned int temp_crc = crc(full_data, check_data_length);
 			if ((temp_crc >> (8*3)) == 10 ) {
 				printf("Found in %zu rounds!\n", rounds);
+				memcpy(color_data, temp_color_data, length);
 				searching = 0;
 			}
 			free(check_data_buff);
@@ -104,8 +107,57 @@ void random_data_change(unsigned char *color_data, int width, int length) {
 	} while(searching == 1);
 }
 
-int change_idat_content(unsigned char *addr, unsigned char *message, int accuracy, unsigned long offset) {
-	//printf("Starting IDAT Tranform\n");
+void build_png_file(struct PNG_FILE_STRUCT *png_file, char *out_file_name) {
+	FILE *fp;
+
+	fp = fopen(out_file_name, "w");
+
+	union{
+		unsigned char data[sizeof(struct PNG_START_FILE_STRUCT)];
+		struct PNG_START_FILE_STRUCT png_data;
+	}start_data;
+
+	start_data.png_data = png_file->png_start_data;
+
+	// IHDR Data
+	for(int i = 0; i < sizeof(start_data.data); i++) {
+		fputc(start_data.data[i], fp);
+	}
+	// IDAT Data
+	for(int i = 0; i < 4; i++) {
+		fputc(png_file->png_idat_data.idat_length[i], fp);
+	}
+	for(int i = 0; i < 4; i++) {
+		fputc(png_file->png_idat_data.idat_header[i], fp);
+	}
+	for(int i = 0; i < be32toh(png_file->png_idat_data.idat_data_length); i++) {
+		fputc(png_file->png_idat_data.idat_data[i], fp);
+	}
+	// Generating CRC
+	unsigned char full_data[be32toh(png_file->png_idat_data.idat_data_length)+4];
+	for(int i = 0; i < 4; i++) {
+		full_data[i] = png_file->png_idat_data.idat_header[i];
+	}
+	for(int i = 0; i < be32toh(png_file->png_idat_data.idat_data_length); i++) {
+		full_data[i+4] = png_file->png_idat_data.idat_data[i];
+	}
+
+	unsigned int int_crc = crc(full_data, be32toh(png_file->png_idat_data.idat_data_length));
+	unsigned char new_crc[4];
+
+	for(int i = 0; i < 4; i++) {
+		new_crc[i] = int_crc >> (8*(3-i)) & 0xFF;
+		fputc(new_crc[i], fp);
+	}
+	// IEND Data
+	unsigned char IEND_DATA[12] = { 0x00, 0x00, 0x00, 0x00, 0x49, 0x45, 0x4E, 0x44, 0xAE, 0x42, 0x60, 0x82};
+	for(int i = 0; i < 12; i++) {
+		fputc(IEND_DATA[i], fp);
+	}
+	fclose(fp);
+}
+
+int change_idat_content(unsigned char *addr, struct PNG_FILE_STRUCT *png_file, char *message, int accuracy, unsigned long offset, char *out_file_name) {
 	if(accuracy > 4) {
 		printf("Warning, accuracy cannot be larger than 4");
 		return EXIT_FAILURE;
@@ -113,17 +165,15 @@ int change_idat_content(unsigned char *addr, unsigned char *message, int accurac
 	if(accuracy > 2) {
 		printf("Notice, this could take a long time...");
 	}
-	if(total_idat(addr) < strlen(message)) {
-		printf("Warning, message exceeds IDAT amount");
-		return EXIT_FAILURE;
+	if(total_idat(addr) < strlen((char*)message)) {
+		printf("Warning, message exceeds IDAT amount\n");
+		exit(EXIT_FAILURE);
 	}
 
 	int idat_length = check_header_length(addr, offset);
 	printf("IDAT Length: %d\n", idat_length);
 
-	int prop_found = 0;
 	long size = 1;
-	long rounds = 0;
 	size_t idat_byte_length = 0;
 	unsigned char* idat_data = calloc(size, sizeof(unsigned char));
 	for(size_t i = 0; i <= idat_length; i++) {
@@ -135,7 +185,6 @@ int change_idat_content(unsigned char *addr, unsigned char *message, int accurac
 		idat_byte_length = i;
 	}
 	unsigned char temp_idat_data[idat_byte_length];
-	while(prop_found == 0) {
 	for(int i = 0; i <= idat_length; i++) {
 		temp_idat_data[i] = idat_data[i];
 	}
@@ -146,45 +195,110 @@ int change_idat_content(unsigned char *addr, unsigned char *message, int accurac
 
 	random_data_change(uncom_data_buff, 16, uncom_data_size);
 	
-		free(uncom_data_buff);
+	// Compress Data
+	unsigned char *com_data_buff;
+	size_t com_data_size = 0;
+	zlib_compress_data(uncom_data_buff, uncom_data_size, &com_data_buff, &com_data_size);
 
-		//printf("Found %d in %d rounds\n", checked_crc ,rounds);
-		//printf("Full CRC: %08X\n", crcnum);
-		//printf("Original: %02X\n", idat_data[j]);
-		//printf("Change offset: %d to hex: %02X\n", j, temp_idat_data[j]);
-		//addr[offset+8+j] = temp_idat_data[j];
-		//update_file_crc(addr, offset, crcnum);
-		prop_found = 1;
+	png_file->png_idat_data.idat_data = calloc(com_data_size, sizeof(unsigned char));
+
+	png_file->png_idat_data.idat_data_length = be32toh(com_data_size);
+
+	for(size_t i = 0; i < com_data_size; i++) {
+		png_file->png_idat_data.idat_data[i] = com_data_buff[i];
 	}
 
+	// Build PNG File
+	build_png_file(png_file, out_file_name);
+
+	free(uncom_data_buff);
+	free(com_data_buff);
 	free(idat_data);
+	free(png_file->png_idat_data.idat_data);
 
 	return 0;
 }
 
 // This is where it all starts
-int main() {
+int main(int argc, char **argv) {
 	FILE *fp;
 	size_t i = 0;
 	unsigned long offset = 0;
-	unsigned char *message = malloc(sizeof(char));
-	message[0] = '\0';
+	struct PNG_FILE_STRUCT png_file_data;
+	char *in_file_name = NULL;
+	char *out_file_name = NULL;
+	char *message = NULL;
+
+	static const struct option long_options[] = {
+		{"help", no_argument, NULL, 'h'},
+		{"file", required_argument, NULL, 'f'},
+		{"outfile", required_argument, NULL, 'o'},
+		{"message", required_argument, NULL, 'm'},
+		{0, 0, 0, 0}
+	};
+
+	const char* usage =
+		"Usage: crc [options]\n"
+		"  -h, --help		Shows help message\n"
+		"  -f, --file		Denotes input file\n"
+		"  -o, --outfile	Denotes output file\n"
+		"  -m, --message	Encoded message\n"
+		"\n";
+
+	int c;
+	while (1) {
+		int option_index = 0;
+		c = getopt_long(argc, argv, "hf:o:m:", long_options ,&option_index);
+		if(c == -1) {
+			break;
+		}
+		switch(c) {
+			case 'h':
+				printf("%s", usage);
+				exit(EXIT_SUCCESS);
+			case 'f':
+				in_file_name = optarg;
+				break;
+			case 'o':
+				out_file_name = optarg;
+				break;
+			case 'm':
+				message = optarg;
+				break;
+		}
+	}
+
+	if(in_file_name == NULL) {
+		printf("Input file required!\n");
+		exit(EXIT_FAILURE);
+	} else if(out_file_name == NULL) {
+		printf("Output file required!\n");
+		exit(EXIT_FAILURE);
+	} else if(message == NULL) {
+		printf("Message required!\n");
+		exit(EXIT_FAILURE);
+	}
 
 	if(sodium_init() == -1) {
 		return EXIT_FAILURE;
 	}
 
-	fp = fopen("./1.png", "rt");
+	fp = fopen(in_file_name, "rt");
 	if (fp == NULL) {
-		return EXIT_FAILURE;
+		printf("File error\n");
+		exit(EXIT_FAILURE);
 	}
 
 	unsigned char *file_data = file_to_char_array(fp, &i);
 	fclose(fp);
 
+	populate_start_png(file_data, &png_file_data.png_start_data);
+
 	offset = first_idat(file_data);
-	change_idat_content(file_data, message, 1, offset);
+
+	populate_idat_png(file_data, &png_file_data.png_idat_data, offset);
+
+	change_idat_content(file_data, &png_file_data, message, 1, offset, out_file_name);
+
 	free(file_data);
-	free(message);
-	//create_cc_file(file_data, i);
 }

include/CRCLib.h

@@ -1,3 +1,7 @@
+/*
+ * Code Implemented From: https://www.w3.org/TR/PNG/#D-CRCAppendix
+*/
+
 /* Table of CRCs of all 8-bit messages. */
 unsigned long crc_table[256];
    

include/crc.h

@@ -1,6 +1,8 @@
+#pragma once
 
 int check_file_header(char *addr);
 int check_header_length(unsigned char *addr, long offset);
 unsigned long first_idat(unsigned char *addr);
 int total_idat(unsigned char *addr);
-int change_idat_content(unsigned char *addr, unsigned char *message, int accuracy, unsigned long offset);
+void build_png_file(struct PNG_FILE_STRUCT *png_file, char *out_file_name);
+int change_idat_content(unsigned char *addr, struct PNG_FILE_STRUCT *png_file, char *message, int accuracy, unsigned long offset, char *out_file_name);

include/crc_util.h

@@ -1,7 +1,37 @@
 #include <stdio.h>
+#include <stdint.h>
+
+#pragma once
 
 // PNG File Struct
-struct PNG
+struct PNG_START_FILE_STRUCT {
+	unsigned char file_sig[8];
+	unsigned char ihdr_length[4];
+	unsigned char ihdr_header[4];
+	unsigned char file_width[4];
+	unsigned char file_height[4];
+	unsigned char bit_depth[1];
+	unsigned char color_type[1];
+	unsigned char compression_method[1];
+	unsigned char filter_method[1];
+	unsigned char interlace_method[1];
+	unsigned char ihdr_crc[4];
+};
+
+struct PNG_IDAT_FILE_STRUCT {
+	union{
+		unsigned char idat_length[4];
+		uint32_t idat_data_length;
+	};
+	unsigned char idat_header[4];
+	unsigned char idat_crc[4];
+	unsigned char *idat_data;
+};
+
+struct PNG_FILE_STRUCT {
+	struct PNG_START_FILE_STRUCT png_start_data;
+	struct PNG_IDAT_FILE_STRUCT png_idat_data;
+};
 
 extern const long png_signature[8];
 
@@ -9,3 +39,5 @@ int check_header_length(unsigned char *addr, long offset);
 int check_file_header(char *addr);
 int create_cc_file(unsigned char *addr, unsigned long file_length);
 unsigned char* file_to_char_array(FILE *in_file, size_t* size);
+void populate_start_png(unsigned char *addr, struct PNG_START_FILE_STRUCT *png_data);
+void populate_idat_png(unsigned char *addr, struct PNG_IDAT_FILE_STRUCT *png_data, unsigned long offset);

src/compress_util.c

@@ -6,6 +6,9 @@
 
 #define CHUNK 1024 
 
+/*
+ * Built from exmaple provided in: https://zlib.net/zlib_how.html
+*/
 void zlib_decompress_data(unsigned char *data_chunk, size_t file_length, unsigned char **buff, size_t *sz) {
         int ret;
         unsigned int have;
@@ -68,6 +71,9 @@ void zlib_decompress_data(unsigned char *data_chunk, size_t file_length, unsigne
         fclose(of);
 }
 
+/*
+ * Built from exmaple provided in: https://zlib.net/zlib_how.html
+*/
 void zlib_compress_data(unsigned char *data_chunk, size_t file_length, unsigned char **buff, size_t *sz) {
         int ret, flush;
         unsigned int have;

src/crc_util.c

@@ -27,6 +27,34 @@ int check_file_header(char *addr) {
 
 }
 
+void populate_idat_png(unsigned char *addr, struct PNG_IDAT_FILE_STRUCT *png_data, unsigned long offset) {
+	unsigned long cur_idat_length = 0;
+	for(int i = 0; i < 4; i++){
+		png_data->idat_length[i] = addr[i+offset];
+	}
+
+	for(int i = 0; i < 4; i++){
+		cur_idat_length += (png_data->idat_length[i] << (24-(8*i)));
+	}
+
+	for(int i = 0; i < 4; i++){
+		png_data->idat_header[i] = addr[i+offset+4];
+	}
+}
+
+void populate_start_png(unsigned char *addr, struct PNG_START_FILE_STRUCT *png_data) {
+	union{
+		unsigned char *data;
+		struct PNG_START_FILE_STRUCT *png_data;
+	}png;
+
+	png.png_data = png_data;
+
+	for(int i = 0; i < sizeof(struct PNG_START_FILE_STRUCT); i++) {
+		png.data[i] = addr[i];
+	}
+}
+
 int create_cc_file(unsigned char *addr, unsigned long file_length) {
         FILE *fp;
         fp = fopen("png2.png", "w");