1 /* $OpenBSD: mangle.c,v 1.2 2009/12/08 21:10:24 drahn Exp $ */ 2 /* 3 * Copyright (c) 2009 Dale Rahn. 4 * All rights reserved. 5 * 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include <sys/types.h> 29 #include <sys/stat.h> 30 #include <fcntl.h> 31 #include <unistd.h> 32 #include <stdio.h> 33 #include <string.h> 34 #include "mangle.h" 35 36 /* 37 * supports randomizing up to 32 characters, if an identifier is longer than 38 * 32 characters, we only modify the first 32 characters of it. 39 * 40 * However not all of the 32 characters will really be randomized as 41 * 2^32 (uint32_t gives a maximum string of cmpPQeaa[a]* 42 * Dont thing this will really matter.... 43 * 44 * HOWEVER this does not mean we want to change the MAX_KEY_STR_LEN to 6 45 * because then all strings len >= 6 would use from the same index pool. 46 */ 47 #define MAX_KEY_STR_LEN 32 48 uint32_t key[MAX_KEY_STR_LEN]; 49 50 char *filename = "mangledata"; 51 52 int key_fd = -1; 53 void 54 init_mangle_state() 55 { 56 int failed = 0; 57 ssize_t len; 58 int i, ret; 59 60 /* open file if it exists, else init to zeros */ 61 struct stat sb; 62 63 ret = stat(filename, &sb); 64 65 if (ret != -1 && sb.st_size == sizeof(key)) { 66 key_fd = open(filename, O_RDWR); 67 } 68 69 if (ret == -1 || key_fd == -1) 70 failed = 1; 71 72 if (failed == 0) { 73 len = read(key_fd, key, sizeof(key)); 74 if (len != sizeof(key)) { 75 failed = 1; 76 } 77 } 78 79 if (failed == 1) { 80 if (key_fd != -1) { 81 close(key_fd); 82 key_fd = -1; 83 } 84 for (i = 0; i < MAX_KEY_STR_LEN; i++) { 85 key[i] = 0; 86 } 87 } 88 } 89 90 void 91 fini_mangle_state() 92 { 93 int len; 94 if (key_fd == -1) { 95 /* open file for create/truncate */ 96 key_fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0666); 97 } else { 98 /* seek to the beginning */ 99 lseek(key_fd, 0, SEEK_SET); 100 } 101 if (key_fd != -1) { 102 /* write file */ 103 len = write(key_fd, key, sizeof(key)); 104 if (len != sizeof(key)) { 105 printf("writing file failed\n"); 106 } 107 close(key_fd); 108 key_fd = -1; 109 } 110 } 111 112 void 113 dump_mangle_state() 114 { 115 int i; 116 117 for (i = 0; i < MAX_KEY_STR_LEN; i++) { 118 printf("key %d %d\n", i, key[i]); 119 } 120 } 121 122 char validchars[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 123 #define NUM_KEYS (sizeof(validchars)-1) 124 125 void 126 mangle_str(char *str) 127 { 128 int i; 129 int len; 130 int keyval; 131 132 len = strlen(str); 133 if (len == 0) 134 return; /* nothing to mangle */ 135 136 if (len > MAX_KEY_STR_LEN) 137 len = MAX_KEY_STR_LEN; 138 139 keyval = key[len-1]++; 140 141 for (i = 0; i < len; i++) { 142 int idx = keyval % NUM_KEYS; 143 keyval = keyval / NUM_KEYS; 144 str[i] = validchars[idx]; 145 146 } 147 } 148 149