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/*
* spreadspace avr utils
*
*
* Copyright (C) 2013 Christian Pointner <equinox@spreadspace.org>
*
* This file is part of spreadspace avr utils.
*
* spreadspace avr utils 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
* any later version.
*
* spreadspace avr utils 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 spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdint.h>
#include <ctype.h>
#include <stdio.h>
#include <termios.h>
#define EEPROM_SIZE 1024
typedef uint8_t keyslot_t[8];
/* this generates a Fletcher8 checksum */
/* code from: http://stackoverflow.com/questions/13491700/8-bit-fletcher-checksum-of-16-byte-data */
uint8_t generate_csum(keyslot_t data)
{
uint16_t sum1 = 0xf, sum2 = 0xf, len = sizeof(keyslot_t)-1;
do { sum2 += ( sum1 += *data++ ); } while (--len);
return sum2<<4 | sum1;
}
int send_key(keyslot_t key, FILE* dev)
{
fwrite(key, sizeof(keyslot_t), 1, dev);
fflush(dev);
char tmp;
while(fread(&tmp, 1, 1, dev)) {
fwrite(&tmp, 1, 1, stdout);
if(tmp == 0) return 1;
if(tmp == '.') return 0;
}
return 0;
}
int main(int argc, char* argv[])
{
if(argc<2) {
fprintf(stderr, "Usage: update-keys <device>\n");
return -1;
}
FILE* dev;
dev = fopen(argv[1], "r+");
if(!dev) {
fprintf(stderr, "fopen failed!\n");
return -2;
}
int fd = fileno(dev);
struct termios t;
tcgetattr(fd, &t);
t.c_lflag &= ~(ICANON | ECHO);
t.c_iflag &= ~(ICRNL | INLCR | IXON | IXOFF);
cfmakeraw(&t);
tcflush(fd, TCIOFLUSH);
tcsetattr(fd, TCSANOW, &t);
fprintf(dev, "e");
char* line = NULL;
size_t len = 0;
int line_num = 0;
keyslot_t key;
int key_num = 0;
for(;;) {
ssize_t ret = getline(&line, &len, stdin);
if(ret <= 0) break;
line_num++;
int i;
for(i=0; i<len; ++i) {
if(!isxdigit(line[i])) {
line[i] = 0;
break;
}
}
if(i & 1 || i == 0 || i > (sizeof(keyslot_t)-1)*2) {
fprintf(stderr, "ignoring invalid key (odd number of digits or empty string or too long) at line %d\n", line_num);
continue;
}
uint8_t tmp[3];
int j;
tmp[2] = 0;
for(j = 0; j<(i/2); ++j) {
tmp[0] = line[j*2];
tmp[1] = line[j*2 + 1];
key[j] = (char)strtoul(tmp, NULL, 16);
}
for(j=i/2; j < sizeof(keyslot_t)-1; ++j) {
key[j] = 0;
}
key[sizeof(keyslot_t)-1] = generate_csum(key);
if(send_key(key, dev)) {
fprintf(stderr, "send_key failed at keyslot %d\n", key_num);
return 1;
}
key_num++;
if(key_num > EEPROM_SIZE/sizeof(keyslot_t)) {
fprintf(stderr, "reached maximum number of key slots (%d), will ignore remaining keys\n", (int)(EEPROM_SIZE/sizeof(keyslot_t)));
break;
}
}
printf("\nread %d keys from STDIN - filling rest of keystore with invalid keys\n", key_num);
int i;
for(i=0; i<=sizeof(keyslot_t)-1; ++i) key[i] = 0xFF;
for(i=key_num; i < EEPROM_SIZE/sizeof(keyslot_t); ++i) {
if(send_key(key, dev)) {
fprintf(stderr, "send_key failed at keyslot %d\n", key_num);
return 1;
}
key_num++;
}
printf("\nwrite of %d keys finished\n", key_num);
return 0;
}
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