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1 /* |
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2 * base64.h -- base64 encoding and decoding |
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3 * |
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4 * Copyright (c) 2013-2015 David Demelier <markand@malikania.fr> |
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5 * |
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6 * Permission to use, copy, modify, and/or distribute this software for any |
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7 * purpose with or without fee is hereby granted, provided that the above |
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8 * copyright notice and this permission notice appear in all copies. |
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9 * |
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10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
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11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
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13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
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16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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17 */ |
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18 |
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19 #ifndef _BASE_64_H_ |
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20 #define _BASE_64_H_ |
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21 |
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22 /** |
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23 * @file Base64.h |
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24 * @brief Base64 encoding and decoding |
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25 */ |
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26 |
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27 #include <stdexcept> |
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28 #include <string> |
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29 |
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30 namespace base64 { |
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31 |
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32 /** |
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33 * Get the base 64 character from the 6-bits value. |
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34 * |
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35 * @pre value must be valid |
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36 * @param value the value |
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37 */ |
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38 unsigned char lookup(unsigned int value) noexcept; |
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39 |
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40 /** |
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41 * Get the integer value from the base 64 character. |
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42 * |
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43 * @pre ch must be a valid base 64 character but not '=' |
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44 * @param ch the base64 character |
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45 */ |
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46 unsigned int rlookup(unsigned char ch); |
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47 |
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48 /** |
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49 * Check if the given character is a valid base 64 character. |
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50 * |
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51 * @param char the character |
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52 * @return true if the character is valid |
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53 */ |
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54 bool isValid(unsigned char) noexcept; |
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55 |
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56 /** |
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57 * Encode the input to the output. Requirements: |
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58 * InputIt must be InputIterator |
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59 * OutputIt must be OutputIterator |
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60 * |
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61 * @param input the beginning |
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62 * @param end the end of the data |
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63 * @param output the output destination |
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64 * @return output |
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65 */ |
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66 template <typename InputIt, typename OutputIt> |
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67 OutputIt encode(InputIt input, InputIt end, OutputIt output) |
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68 { |
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69 while (input != end) { |
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70 char inputbuf[3] = { 0, 0, 0 }; |
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71 int count; |
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72 |
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73 for (count = 0; count < 3 && input != end; ++count) { |
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74 inputbuf[count] = *input++; |
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75 } |
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76 |
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77 *output++ = lookup(inputbuf[0] >> 2 & 0x3f); |
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78 *output++ = lookup((inputbuf[0] << 4 & 0x3f) | (inputbuf[1] >> 4 & 0x0f)); |
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79 *output++ = (count < 2) ? '=' : lookup((inputbuf[1] << 2 & 0x3c) | (inputbuf[2] >> 6 & 0x03)); |
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80 *output++ = (count < 3) ? '=' : lookup(inputbuf[2] & 0x3f); |
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81 } |
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82 |
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83 return output; |
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84 } |
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85 |
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86 /** |
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87 * Decode the input to the output. Requirements: |
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88 * InputIt must be InputIterator |
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89 * OutputIt must be OutputIterator |
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90 * |
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91 * @param input the beginning |
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92 * @param end the end of the data |
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93 * @param output the output destination |
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94 * @return output |
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95 * @throw std::invalid_argument on bad base64 string |
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96 */ |
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97 template <typename InputIt, typename OutputIt> |
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98 OutputIt decode(InputIt input, InputIt end, OutputIt output) |
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99 { |
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100 while (input != end) { |
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101 char inputbuf[4] = { -1, -1, -1, -1 }; |
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102 int count; |
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103 |
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104 for (count = 0; count < 4 && input != end; ++count) { |
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105 if (*input != '=') { |
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106 /* Check if the character is valid and get its value */ |
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107 if (isValid(*input)) { |
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108 inputbuf[count] = rlookup(*input); |
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109 } else { |
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110 throw std::invalid_argument{"invalid base64 string"}; |
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111 } |
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112 } else { |
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113 /* A base 64 string cannot start with "=" or "==" */ |
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114 if (count == 0 || count == 1) { |
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115 throw std::invalid_argument{"invalid or truncated base64 string"}; |
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116 } |
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117 } |
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118 |
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119 input++; |
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120 } |
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121 |
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122 if (count != 4) { |
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123 throw std::invalid_argument("truncated string"); |
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124 } |
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125 |
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126 *output++ = static_cast<unsigned char>(((inputbuf[0] << 2) & 0xfc) | ((inputbuf[1] >> 4) & 0x03)); |
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127 |
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128 if (inputbuf[2] != -1) { |
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129 *output++ = static_cast<unsigned char>(((inputbuf[1] << 4) & 0xf0) | ((inputbuf[2] >> 2) & 0x0f)); |
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130 } |
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131 if (inputbuf[3] != -1) { |
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132 /* "XY=Z" is not allowed */ |
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133 if (inputbuf[2] == -1) { |
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134 throw std::invalid_argument{"invalid base64 string"}; |
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135 } |
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136 |
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137 *output++ = static_cast<unsigned char>(((inputbuf[2] << 6) & 0xc0) | (inputbuf[3] & 0x3f)); |
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138 } |
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139 } |
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140 |
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141 return output; |
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142 } |
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143 |
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144 /** |
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145 * Encode a string. |
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146 * |
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147 * @param input the input string |
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148 * @return the base64 formatted string |
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149 */ |
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150 std::string encode(const std::string &input); |
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151 |
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152 /** |
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153 * Decode a string. |
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154 * |
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155 * @param input the base64 formatted string |
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156 * @return the original string |
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157 * @throw std::invalid_argument on bad base64 string |
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158 */ |
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159 std::string decode(const std::string &input); |
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160 |
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161 } // !base64 |
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162 |
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163 #endif // !_BASE_64_H_ |
