1 | /* |
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2 | * base64.c -- Base64 Mime encoding |
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3 | * |
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4 | * Copyright (c) Go Ahead Software Inc., 1995-1999. All Rights Reserved. |
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5 | * |
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6 | * See the file "license.txt" for usage and redistribution license requirements |
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7 | */ |
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8 | |
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9 | /******************************** Description *********************************/ |
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10 | |
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11 | /* |
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12 | * The base64 command encodes and decodes a string in mime base64 format |
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13 | */ |
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14 | |
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15 | /********************************* Includes ***********************************/ |
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16 | |
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17 | #include "wsIntrn.h" |
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18 | |
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19 | /******************************** Local Data **********************************/ |
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20 | /* |
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21 | * Mapping of ANSI chars to base64 Mime encoding alphabet (see below) |
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22 | */ |
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23 | |
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24 | static char_t map64[] = { |
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25 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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26 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, |
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27 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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28 | 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, |
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29 | -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, |
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30 | 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, |
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31 | -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, |
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32 | 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, |
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33 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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34 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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35 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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36 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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37 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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38 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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39 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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40 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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41 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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42 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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43 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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44 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
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45 | }; |
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46 | |
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47 | static char_t alphabet64[] = { |
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48 | 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', |
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49 | 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', |
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50 | 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', |
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51 | 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', |
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52 | 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', |
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53 | 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', |
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54 | 'w', 'x', 'y', 'z', '0', '1', '2', '3', |
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55 | '4', '5', '6', '7', '8', '9', '+', '/', |
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56 | }; |
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57 | |
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58 | /*********************************** Code *************************************/ |
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59 | /* |
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60 | * Decode a buffer from "string" and into "outbuf" |
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61 | */ |
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62 | |
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63 | int websDecode64(char_t* outbuf, char_t* string, int outlen) |
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64 | { |
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65 | unsigned long shiftbuf; |
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66 | char_t* cp; |
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67 | char_t* op; |
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68 | int c, i, j, shift; |
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69 | |
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70 | op = outbuf; |
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71 | *op = '\0'; |
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72 | cp = string; |
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73 | while (*cp && *cp != '=') { |
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74 | /* |
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75 | * Map 4 (6bit) input bytes and store in a single long (shiftbuf) |
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76 | */ |
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77 | shiftbuf = 0; |
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78 | shift = 18; |
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79 | for (i = 0; i < 4 && *cp && *cp != '='; i++, cp++) { |
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80 | c = map64[*cp & 0xff]; |
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81 | if (c == -1) { |
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82 | error(E_L, E_LOG, T("Bad string: %s at %c index %d"), string, |
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83 | c, i); |
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84 | return -1; |
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85 | } |
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86 | shiftbuf = shiftbuf | (c << shift); |
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87 | shift -= 6; |
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88 | } |
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89 | /* |
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90 | * Interpret as 3 normal 8 bit bytes (fill in reverse order). |
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91 | * Check for potential buffer overflow before filling. |
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92 | */ |
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93 | --i; |
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94 | if ((op + i) >= &outbuf[outlen]) { |
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95 | gstrcpy(outbuf, T("String too big")); |
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96 | return -1; |
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97 | } |
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98 | for (j = 0; j < i; j++) { |
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99 | *op++ = (char_t) ((shiftbuf >> (8 * (2 - j))) & 0xff); |
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100 | } |
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101 | *op = '\0'; |
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102 | } |
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103 | return 0; |
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104 | } |
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105 | |
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106 | |
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107 | /******************************************************************************/ |
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108 | /* |
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109 | * Encode a buffer from "string" into "outbuf" |
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110 | */ |
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111 | |
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112 | void websEncode64(char_t* outbuf, char_t* string, int outlen) |
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113 | { |
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114 | unsigned long shiftbuf; |
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115 | char_t* cp; |
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116 | char_t* op; |
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117 | int x, i, j, shift; |
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118 | |
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119 | op = outbuf; |
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120 | *op = '\0'; |
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121 | cp = string; |
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122 | while (*cp) { |
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123 | /* |
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124 | * Take three characters and create a 24 bit number in shiftbuf |
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125 | */ |
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126 | shiftbuf = 0; |
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127 | for (j = 2; j >= 0 && *cp; j--, cp++) { |
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128 | shiftbuf |= ((*cp & 0xff) << (j * 8)); |
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129 | } |
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130 | /* |
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131 | * Now convert shiftbuf to 4 base64 letters. The i,j magic calculates |
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132 | * how many letters need to be output. |
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133 | */ |
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134 | shift = 18; |
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135 | for (i = ++j; i < 4 && op < &outbuf[outlen] ; i++) { |
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136 | x = (shiftbuf >> shift) & 0x3f; |
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137 | *op++ = alphabet64[(shiftbuf >> shift) & 0x3f]; |
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138 | shift -= 6; |
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139 | } |
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140 | /* |
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141 | * Pad at the end with '=' |
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142 | */ |
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143 | while (j-- > 0) { |
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144 | *op++ = '='; |
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145 | } |
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146 | *op = '\0'; |
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147 | } |
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148 | } |
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149 | /******************************************************************************/ |
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