uint64_t first_complete_message_size(const CNetworkConfig& config, evbuffer* input, bool& fComplete, bool& fBadMsgStart)
{
size_t nTotal = evbuffer_get_length(input);
uint64_t nMessageSize;
const int size_needed = config.header_msg_size_offset + config.header_msg_size_size;
fComplete = false;
fBadMsgStart = false;
// Assume 4-bytes until there's a reason not to.
assert(config.header_msg_size_size == 4);
if (nTotal < static_cast<size_t>(size_needed))
return 0;
evbuffer_iovec v;
if (evbuffer_peek(input, size_needed, nullptr, &v, 1) == 1) {
const unsigned char* ptr = static_cast<const unsigned char*>(v.iov_base);
if (!config.message_start.empty() && memcmp(ptr, &config.message_start[0], config.message_start.size()) != 0) {
fBadMsgStart = true;
return 0;
}
nMessageSize = get_message_length(ptr + config.header_msg_size_offset) + config.header_size;
} else {
std::vector<unsigned char> partial_header(size_needed);
int ret = evbuffer_copyout(input, &partial_header[0], size_needed);
assert(ret == size_needed);
(void)ret;
if (!config.message_start.empty() && memcmp(&partial_header[0], &config.message_start[0], config.message_start.size()) != 0) {
fBadMsgStart = true;
return 0;
}
nMessageSize = get_message_length(&partial_header[0] + config.header_msg_size_offset) + config.header_size;
}
if (nTotal >= nMessageSize)
fComplete = true;
return nMessageSize;
}
result write_pointer_table(FILE *out, Messages *m) {
int i;
size_t message_length;
unsigned short p;
p = 0;
for (i = 0; i < m->count; i++) {
if(fwrite(&p, 2, 1, out) != 1) {
fprintf(stderr, "ERROR: Couldn't write pointer table at message #%d\n", i);
return ERROR;
}
message_length = get_message_length(&m->messages[i]);
p = (unsigned short)(message_length + p);
}
return OK;
}
static char * test_get_message_length () {
int lengths[] = {40, 24, 39, 76, 52, 79, 66, 88, 51, 22, 39, 42, 71, 40, 49, 32, 31, 67, 106, 20};
/*
for (int i = 0 ; i < get_number_of_messages() ; i++) {
int length;
length = get_message_length(i);
printf("%d, ", length);
}
*/
for (int i = 0 ; i < get_number_of_messages() ; i++) {
int length;
length = get_message_length(i);
printf("\t... Checking length of message index %d (%d)\n", i, length);
mu_assert("Found wrong message length.", length == lengths[i]);
}
return 0;
}
static char * test_read_message () {
char * messages[] = {"Godhasmadeofonebloodallpeoplesoftheearth", \
"Thereisdignityinalllabor", \
"Imaginationismoreimportantthanknowledge", \
"Donotdwellinthepastdonotdreamofthefutureconcentratethemindonthepresentmoment", \
"Thebestplacetofindahelpinghandisattheendofyourownarm", \
"IfyourstrengthissmalldontcarryheavyburdensIfyourwordsareworthlessdontgiveadvice", \
"Ifyouarepatientinonemomentofangeryouwillescapeahundreddaysofsorrow", \
"Ifyoumustplaydecideuponthreethingsatthestarttherulesofthegamethestakesandthequittingtime", \
"Learningisatreasurethatwillfollowitsownereverywhere", \
"Achangeisasgoodasarest", \
"Aknownmistakeisbetterthananunknowntruth", \
"Arroganceisaweedthatgrowsmostlyonadunghill", \
"Acuttingwordisworsethanabowstringacutmayhealbutthecutofthetonguedoesnot", \
"Afoollooksfordungwherethecowneverbrowsed", \
"Ifyoudontstandforsomethingyouwillfallforsomething", \
"Adversityisthefoundationofvirtue", \
"Anexcessofcourtesyisdiscourtesy", \
"Opinionsfoundedonprejudicearealwayssustainedwiththegreatestviolence", \
"InacountrywellgovernedpovertyissomethingtobeashamedofInacountrybadlygovernedwealthissomethingtobeashamedof", \
"Thecautiousseldomerr" \
};
for (int i = 0 ; i < get_number_of_messages() ; i++) {
int message_length = get_message_length(i);
char *msg = read_message(i);
printf("\t... Checking correctness of message %d\n", i);
for (int pos = 0 ; pos < message_length ; pos++) {
/* printf("POS[%d] msg[%c] messages[%c]\n", pos, msg[pos], messages[i][pos]); */
mu_assert("Found wrong character in message.", msg[pos] = messages[i][pos]);
}
free(msg);
}
return 0;
}
int main(int argc,char** argv) {
unsigned char mask_table[] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 };
FILE *file_handle;
FILE *message_handle;
FILE *hidden_message_handle;
if(argc!=4) {
printf("*** Steganography by LSB substitution***\nUsage: %s [-e][-d] [source file] [destination file] [text file]\nMode\n-e : Add text to Image\n-d : Extract text from Image\n",argv[0]);
exit(1);
}
/* HANDLING FILE OPENING AND ERRORS */
file_handle=fopen(argv[1],"r");
if (file_handle == NULL) {
fprintf(stderr, "Can't open input file %s\n",argv[1]);
exit(1);
}
hidden_message_handle=fopen(argv[2],"w");
if (hidden_message_handle== NULL) {
fprintf(stderr, "Cannot create output file %s\n",argv[2]);
exit(1);
}
message_handle=fopen(argv[3],"r");
if (message_handle== NULL) {
fprintf(stderr, "Can't open text input file %s\n",argv[3]);
exit(1);
}
int hidden_message_length=get_message_length(message_handle);
int c=0;
/* Generate file with the same header. Copy first 128 bytes */
char tmp_sig_cpy;
int offset=get_image_data_offset(file_handle);
rewind(file_handle);
for(int i=0;i<offset;i++) {
tmp_sig_cpy=fgetc(file_handle);
fputc(tmp_sig_cpy,hidden_message_handle);
c++;
}
/* Made file as .bmp */
char file_buffer; // Temp variable for one byte from file
char message_buffer; // Temp buffer for one byte of message
/*
After offset has been read and the file header has been written as is for the virgin image - the length of the hidden message is written as the first byte. This length is then used while decrypting the text from the image.
*/
do {
int bit_of_message;
if(!feof(message_handle)) {
message_buffer=fgetc(message_handle);
for(int i=0;i<8;i++) { //Do this for every bit in every byte of the virgin-image
file_buffer=fgetc(file_handle);
c++;
int file_byte_lsb = file_buffer & 1; // AND WITH 1 TO GET THE VALUE OF LSB. AND MAKES IT 0 IF LSB IS 0 OR 1 IF IT IS 1
bit_of_message=mask_table[i] & message_buffer;
if(file_byte_lsb==bit_of_message) {
fputc(file_buffer,hidden_message_handle);
}
else {
if(file_byte_lsb==0)
file_buffer = (file_buffer | 1);
else
file_buffer = (file_buffer & ~1);
// logic to flip the LSB bit of file_buffer and put it into a file with putc()
fputc(file_buffer,hidden_message_handle);
}
}
}
else {
tmp_sig_cpy=fgetc(file_handle);
fputc(tmp_sig_cpy,hidden_message_handle);
c++;
}
} while(!feof(file_handle));
/* Clean up before exit */
fclose(file_handle);
fclose(hidden_message_handle);
fclose(message_handle);
printf("\nOffset for image data = %d \nNumber of bytes navigated = %d\n",offset,c);
}
void ERROR_define(const char *pattern, char *arg[])
{
uchar c;
char *msg = NULL;
int len;
int narg = 0;
ERROR_clear();
if ((intptr_t)pattern >= 0 && (intptr_t)pattern < 256)
{
ERROR_current->info.code = (int)(intptr_t)pattern;
pattern = _message[(int)(intptr_t)pattern];
if (*pattern == '.')
{
narg = pattern[1] - '0';
pattern += 2;
}
}
else if ((intptr_t)pattern == E_ABORT)
{
ERROR_current->info.code = E_ABORT;
pattern = "";
}
else
{
ERROR_current->info.code = E_CUSTOM;
if (arg)
{
msg = (char *)pattern;
for (;;)
{
c = *msg++;
if (c == 0)
break;
if (c == '&')
{
c = *msg++;
if (c >= '1' && c <= '4')
{
c -= '0';
if (c > narg)
narg = c;
}
}
}
}
}
if (narg)
{
len = get_message_length(pattern, arg, narg);
if (len)
{
msg = STRING_new(NULL, len);
ERROR_current->info.msg = msg;
ERROR_current->info.free = TRUE;
if (EXEC_debug)
{
int i;
strcpy(msg, pattern);
msg += strlen(pattern);
for (i = 0; i < narg; i++)
{
*msg++ = '|';
if (arg[i])
{
strcpy(msg, arg[i]);
msg += strlen(arg[i]);
}
}
}
else
{
for (;;)
{
c = *pattern++;
if (c == 0)
break;
if (c == '&')
{
c = *pattern++;
if (c >= '1' && c <= '4')
{
c -= '1';
if (arg[c])
{
len = strlen(arg[c]);
memcpy(msg, arg[c], len);
msg += len;
}
}
}
else
*msg++ = c;
}
*msg = 0;
}
/*fprintf(stderr, "msg: %s\n", ERROR_current->info.msg);
if (strcmp(ERROR_current->info.msg, "Type mismatch: wanted WebView, got Function instead") == 0)
{
BREAKPOINT();
STRING_watch = ERROR_current->info.msg;
}*/
}
}
else if (ERROR_current->info.code == E_CUSTOM)
{
if (pattern && *pattern)
{
ERROR_current->info.msg = STRING_new_zero(pattern);
ERROR_current->info.free = TRUE;
}
else
{
ERROR_current->info.msg = (char *)_message[E_UNKNOWN];
ERROR_current->info.free = FALSE;
}
}
else
{
ERROR_current->info.msg = (char *)pattern;
ERROR_current->info.free = FALSE;
}
//fprintf(stderr, "ERROR_define: %p %d '%s'\n", ERROR_current, ERROR_current->info.code, ERROR_current->info.msg);
//STRING_add_char(&ERROR_current->info.msg, 0);
ERROR_current->info.cp = CP;
ERROR_current->info.fp = FP;
ERROR_current->info.pc = PC;
#if DEBUG_ERROR
ERROR_debug("ERROR_define: %s\n", ERROR_current->info.msg);
#endif
}