OpenWrt – Rev 1

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/*
 * Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <libgen.h>
#include <getopt.h>     /* for getopt() */
#include <stdarg.h>

#include "buffalo-lib.h"

#define ERR(fmt, args...) do { \
        fflush(0); \
        fprintf(stderr, "[%s] *** error: " fmt "\n", \
                        progname, ## args ); \
} while (0)

static char *progname;
static char *ifname;
static char *ofname;
static int do_decrypt;

void usage(int status)
{
        FILE *stream = (status != EXIT_SUCCESS) ? stderr : stdout;

        fprintf(stream, "Usage: %s [OPTIONS...]\n", progname);
        fprintf(stream,
"\n"
"Options:\n"
"  -d              decrypt instead of encrypt\n"
"  -i <file>       read input from the file <file>\n"
"  -o <file>       write output to the file <file>\n"
"  -h              show this screen\n"
        );

        exit(status);
}

static const unsigned char *crypt_key1 = (unsigned char *)
        "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
static const unsigned char *crypt_key2 = (unsigned char *)
        "XYZ0123hijklmnopqABCDEFGHrstuvabcdefgwxyzIJKLMSTUVW456789NOPQR";

static void crypt_header(unsigned char *buf, ssize_t len,
                         const unsigned char *key1, const unsigned char *key2)
{
        ssize_t i;

        for (i = 0; i < len; i++) {
                unsigned int j;

                for (j = 0; key1[j]; j++)
                        if (buf[i] == key1[j]) {
                                buf[i] = key2[j];
                                break;
                        }
        }
}

static int crypt_file(void)
{
        unsigned char *buf = NULL;
        ssize_t src_len;
        int err;
        int ret = -1;

        src_len = get_file_size(ifname);
        if (src_len < 0) {
                ERR("unable to get size of '%s'", ifname);
                goto out;
        }

        buf = malloc(src_len);
        if (buf == NULL) {
                ERR("no memory for the buffer");
                goto out;
        }

        err = read_file_to_buf(ifname, buf, src_len);
        if (err) {
                ERR("unable to read from file '%s'", ifname);
                goto out;
        }

        if (do_decrypt)
                crypt_header(buf, 512, crypt_key2, crypt_key1);
        else
                crypt_header(buf, 512, crypt_key1, crypt_key2);

        err = write_buf_to_file(ofname, buf, src_len);
        if (err) {
                ERR("unable to write to file '%s'", ofname);
                goto out;
        }

        ret = 0;

out:
        free(buf);
        return ret;
}

static int check_params(void)
{
        int ret = -1;

        if (ifname == NULL) {
                ERR("no input file specified");
                goto out;
        }

        if (ofname == NULL) {
                ERR("no output file specified");
                goto out;
        }

        ret = 0;

out:
        return ret;
}

int main(int argc, char *argv[])
{
        int res = EXIT_FAILURE;
        int err;

        progname = basename(argv[0]);

        while ( 1 ) {
                int c;

                c = getopt(argc, argv, "di:o:h");
                if (c == -1)
                        break;

                switch (c) {
                case 'd':
                        do_decrypt = 1;
                        break;
                case 'i':
                        ifname = optarg;
                        break;
                case 'o':
                        ofname = optarg;
                        break;
                case 'h':
                        usage(EXIT_SUCCESS);
                        break;
                default:
                        usage(EXIT_FAILURE);
                        break;
                }
        }

        err = check_params();
        if (err)
                goto out;

        err = crypt_file();
        if (err)
                goto out;

        res = EXIT_SUCCESS;

out:
        return res;
}