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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2 | mjames | 1 | #include <stdint.h> |
| 2 | #include <string.h> |
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| 3 | |||
| 4 | static const char encoding_table[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', |
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| 5 | 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', |
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| 6 | 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', |
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| 7 | 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', |
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| 8 | 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', |
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| 9 | 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', |
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| 10 | 'w', 'x', 'y', 'z', '0', '1', '2', '3', |
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| 11 | '4', '5', '6', '7', '8', '9', '+', '/'}; |
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| 12 | |||
| 13 | static const char decoding_table[256] = {['A'] = 0, // using GCC initialiser style |
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| 14 | ['B'] = 1, |
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| 15 | ['C'] = 2, |
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| 16 | ['D'] = 3, |
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| 17 | ['E'] = 4, |
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| 18 | ['F'] = 5, |
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| 19 | ['G'] = 6, |
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| 20 | ['H'] = 7, |
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| 21 | ['I'] = 8, |
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| 22 | ['J'] = 9, |
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| 23 | ['K'] = 10, |
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| 24 | ['L'] = 11, |
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| 25 | ['M'] = 12, |
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| 26 | ['N'] = 13, |
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| 27 | ['O'] = 14, |
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| 28 | ['P'] = 15, |
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| 29 | ['Q'] = 16, |
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| 30 | ['R'] = 17, |
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| 31 | ['S'] = 18, |
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| 32 | ['T'] = 19, |
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| 33 | ['U'] = 20, |
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| 34 | ['V'] = 21, |
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| 35 | ['W'] = 22, |
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| 36 | ['X'] = 23, |
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| 37 | ['Y'] = 24, |
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| 38 | ['Z'] = 25, |
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| 39 | ['a'] = 26, |
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| 40 | ['b'] = 27, |
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| 41 | ['c'] = 28, |
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| 42 | ['d'] = 29, |
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| 43 | ['e'] = 30, |
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| 44 | ['f'] = 31, |
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| 45 | ['g'] = 32, |
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| 46 | ['h'] = 33, |
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| 47 | ['i'] = 34, |
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| 48 | ['j'] = 35, |
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| 49 | ['k'] = 36, |
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| 50 | ['l'] = 37, |
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| 51 | ['m'] = 38, |
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| 52 | ['n'] = 39, |
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| 53 | ['o'] = 40, |
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| 54 | ['p'] = 41, |
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| 55 | ['q'] = 42, |
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| 56 | ['r'] = 43, |
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| 57 | ['s'] = 44, |
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| 58 | ['t'] = 45, |
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| 59 | ['u'] = 46, |
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| 60 | ['v'] = 47, |
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| 61 | ['w'] = 48, |
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| 62 | ['x'] = 49, |
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| 63 | ['y'] = 50, |
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| 64 | ['z'] = 51, |
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| 65 | ['0'] = 52, |
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| 66 | ['1'] = 53, |
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| 67 | ['2'] = 54, |
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| 68 | ['3'] = 55, |
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| 69 | ['4'] = 56, |
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| 70 | ['5'] = 57, |
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| 71 | ['6'] = 58, |
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| 72 | ['7'] = 59, |
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| 73 | ['8'] = 60, |
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| 74 | ['9'] = 61, |
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| 75 | ['+'] = 62, |
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| 76 | ['/'] = 63}; |
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| 77 | |||
| 78 | static const int mod_table[] = {0, 2, 1}; |
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| 79 | |||
| 80 | unsigned char *base64_encode(const unsigned char *data, |
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| 81 | size_t input_length, |
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| 82 | unsigned char *encoded_data, |
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| 83 | size_t *output_length) |
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| 84 | { |
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| 85 | |||
| 86 | *output_length = 4 * ((input_length + 2) / 3); |
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| 87 | |||
| 88 | for (int i = 0, j = 0; i < input_length;) |
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| 89 | { |
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| 90 | |||
| 91 | uint32_t octet_a = i < input_length ? (unsigned char)data[i++] : 0; |
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| 92 | uint32_t octet_b = i < input_length ? (unsigned char)data[i++] : 0; |
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| 93 | uint32_t octet_c = i < input_length ? (unsigned char)data[i++] : 0; |
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| 94 | |||
| 95 | uint32_t triple = (octet_a << 0x10) + (octet_b << 0x08) + octet_c; |
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| 96 | |||
| 97 | encoded_data[j++] = encoding_table[(triple >> 3 * 6) & 0x3F]; |
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| 98 | encoded_data[j++] = encoding_table[(triple >> 2 * 6) & 0x3F]; |
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| 99 | encoded_data[j++] = encoding_table[(triple >> 1 * 6) & 0x3F]; |
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| 100 | encoded_data[j++] = encoding_table[(triple >> 0 * 6) & 0x3F]; |
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| 101 | } |
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| 102 | |||
| 103 | for (int i = 0; i < mod_table[input_length % 3]; i++) |
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| 104 | encoded_data[*output_length - 1 - i] = '='; |
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| 105 | |||
| 106 | return encoded_data; |
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| 107 | } |
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| 108 | |||
| 109 | unsigned char *base64_decode(const char *data, |
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| 110 | size_t input_length, |
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| 111 | unsigned char *decoded_data, |
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| 112 | size_t *output_length) |
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| 113 | { |
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| 114 | if (input_length % 4 != 0) |
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| 115 | return NULL; |
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| 116 | |||
| 117 | *output_length = input_length / 4 * 3; |
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| 118 | if (data[input_length - 1] == '=') |
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| 119 | (*output_length)--; |
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| 120 | if (data[input_length - 2] == '=') |
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| 121 | (*output_length)--; |
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| 122 | |||
| 123 | for (int i = 0, j = 0; i < input_length;) |
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| 124 | { |
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| 125 | |||
| 126 | uint32_t sextet_a = data[i] == '=' ? 0 & i++ : decoding_table[(int)data[i++]]; |
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| 127 | uint32_t sextet_b = data[i] == '=' ? 0 & i++ : decoding_table[(int)data[i++]]; |
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| 128 | uint32_t sextet_c = data[i] == '=' ? 0 & i++ : decoding_table[(int)data[i++]]; |
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| 129 | uint32_t sextet_d = data[i] == '=' ? 0 & i++ : decoding_table[(int)data[i++]]; |
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| 130 | |||
| 131 | uint32_t triple = (sextet_a << 3 * 6) + (sextet_b << 2 * 6) + (sextet_c << 1 * 6) + (sextet_d << 0 * 6); |
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| 132 | |||
| 133 | if (j < *output_length) |
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| 134 | decoded_data[j++] = (triple >> 2 * 8) & 0xFF; |
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| 135 | if (j < *output_length) |
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| 136 | decoded_data[j++] = (triple >> 1 * 8) & 0xFF; |
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| 137 | if (j < *output_length) |
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| 138 | decoded_data[j++] = (triple >> 0 * 8) & 0xFF; |
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| 139 | } |
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| 140 | |||
| 141 | return decoded_data; |
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| 142 | } |