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/* $OpenBSD: mangle.c,v 1.2 2009/12/08 21:10:24 drahn Exp $ */ |
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/* |
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* Copyright (c) 2009 Dale Rahn. |
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* All rights reserved. |
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* |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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#include <sys/types.h> |
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#include <sys/stat.h> |
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#include <fcntl.h> |
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#include <unistd.h> |
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#include <stdio.h> |
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#include <string.h> |
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#include "mangle.h" |
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/* |
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* supports randomizing up to 32 characters, if an identifier is longer than |
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* 32 characters, we only modify the first 32 characters of it. |
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* |
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* However not all of the 32 characters will really be randomized as |
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* 2^32 (uint32_t gives a maximum string of cmpPQeaa[a]* |
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* Dont thing this will really matter.... |
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* |
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* HOWEVER this does not mean we want to change the MAX_KEY_STR_LEN to 6 |
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* because then all strings len >= 6 would use from the same index pool. |
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*/ |
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#define MAX_KEY_STR_LEN 32 |
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uint32_t key[MAX_KEY_STR_LEN]; |
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char *filename = "mangledata"; |
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int key_fd = -1; |
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void |
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init_mangle_state() |
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{ |
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int failed = 0; |
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ssize_t len; |
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int i, ret; |
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/* open file if it exists, else init to zeros */ |
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struct stat sb; |
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ret = stat(filename, &sb); |
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if (ret != -1 && sb.st_size == sizeof(key)) { |
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key_fd = open(filename, O_RDWR); |
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} |
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if (ret == -1 || key_fd == -1) |
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failed = 1; |
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if (failed == 0) { |
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len = read(key_fd, key, sizeof(key)); |
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if (len != sizeof(key)) { |
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failed = 1; |
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} |
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} |
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if (failed == 1) { |
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if (key_fd != -1) { |
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close(key_fd); |
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key_fd = -1; |
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} |
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for (i = 0; i < MAX_KEY_STR_LEN; i++) { |
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key[i] = 0; |
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} |
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} |
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} |
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void |
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fini_mangle_state() |
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{ |
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int len; |
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if (key_fd == -1) { |
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/* open file for create/truncate */ |
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key_fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0666); |
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} else { |
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/* seek to the beginning */ |
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lseek(key_fd, 0, SEEK_SET); |
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} |
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if (key_fd != -1) { |
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/* write file */ |
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len = write(key_fd, key, sizeof(key)); |
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if (len != sizeof(key)) { |
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printf("writing file failed\n"); |
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} |
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close(key_fd); |
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key_fd = -1; |
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} |
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} |
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void |
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dump_mangle_state() |
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{ |
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int i; |
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for (i = 0; i < MAX_KEY_STR_LEN; i++) { |
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printf("key %d %d\n", i, key[i]); |
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} |
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} |
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char validchars[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; |
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#define NUM_KEYS (sizeof(validchars)-1) |
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void |
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mangle_str(char *str) |
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{ |
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int i; |
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int len; |
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int keyval; |
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len = strlen(str); |
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if (len == 0) |
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return; /* nothing to mangle */ |
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if (len > MAX_KEY_STR_LEN) |
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len = MAX_KEY_STR_LEN; |
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keyval = key[len-1]++; |
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for (i = 0; i < len; i++) { |
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int idx = keyval % NUM_KEYS; |
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keyval = keyval / NUM_KEYS; |
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str[i] = validchars[idx]; |
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} |
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} |
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