Base64 library borrowed from HTTPServer implementation...
Base64.cpp@0:687575a500e5, 2014-12-18 (annotated)
- Committer:
- ansond
- Date:
- Thu Dec 18 03:59:35 2014 +0000
- Revision:
- 0:687575a500e5
- Child:
- 1:4920bc5699f3
initial commit
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
ansond | 0:687575a500e5 | 1 | // |
ansond | 0:687575a500e5 | 2 | // Base64 Encoding and Decoding |
ansond | 0:687575a500e5 | 3 | // |
ansond | 0:687575a500e5 | 4 | // @note Copyright © 2013 by Smartware Computing, all rights reserved. |
ansond | 0:687575a500e5 | 5 | // Individuals may use this application for evaluation or non-commercial |
ansond | 0:687575a500e5 | 6 | // purposes. Within this restriction, changes may be made to this application |
ansond | 0:687575a500e5 | 7 | // as long as this copyright notice is retained. The user shall make |
ansond | 0:687575a500e5 | 8 | // clear that their work is a derived work, and not the original. |
ansond | 0:687575a500e5 | 9 | // Users of this application and sources accept this application "as is" and |
ansond | 0:687575a500e5 | 10 | // shall hold harmless Smartware Computing, for any undesired results while |
ansond | 0:687575a500e5 | 11 | // using this application - whether real or imagined. |
ansond | 0:687575a500e5 | 12 | // |
ansond | 0:687575a500e5 | 13 | // author David Smart, Smartware Computing |
ansond | 0:687575a500e5 | 14 | // |
ansond | 0:687575a500e5 | 15 | #ifndef WIN32 |
ansond | 0:687575a500e5 | 16 | #include "mbed.h" |
ansond | 0:687575a500e5 | 17 | #else |
ansond | 0:687575a500e5 | 18 | #include "windows.h" |
ansond | 0:687575a500e5 | 19 | typedef unsigned int uint32_t; |
ansond | 0:687575a500e5 | 20 | #endif |
ansond | 0:687575a500e5 | 21 | #include "Base64.h" |
ansond | 0:687575a500e5 | 22 | |
ansond | 0:687575a500e5 | 23 | static const char encoding_table[] = { |
ansond | 0:687575a500e5 | 24 | 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', |
ansond | 0:687575a500e5 | 25 | 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', |
ansond | 0:687575a500e5 | 26 | 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', |
ansond | 0:687575a500e5 | 27 | 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', |
ansond | 0:687575a500e5 | 28 | 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', |
ansond | 0:687575a500e5 | 29 | 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', |
ansond | 0:687575a500e5 | 30 | 'w', 'x', 'y', 'z', '0', '1', '2', '3', |
ansond | 0:687575a500e5 | 31 | '4', '5', '6', '7', '8', '9', '+', '/' |
ansond | 0:687575a500e5 | 32 | }; |
ansond | 0:687575a500e5 | 33 | |
ansond | 0:687575a500e5 | 34 | static const int mod_table[] = {0, 2, 1}; |
ansond | 0:687575a500e5 | 35 | |
ansond | 0:687575a500e5 | 36 | Base64::Base64() |
ansond | 0:687575a500e5 | 37 | { |
ansond | 0:687575a500e5 | 38 | decoding_table = NULL; |
ansond | 0:687575a500e5 | 39 | } |
ansond | 0:687575a500e5 | 40 | |
ansond | 0:687575a500e5 | 41 | Base64::~Base64() |
ansond | 0:687575a500e5 | 42 | { |
ansond | 0:687575a500e5 | 43 | if (decoding_table) |
ansond | 0:687575a500e5 | 44 | free(decoding_table); |
ansond | 0:687575a500e5 | 45 | } |
ansond | 0:687575a500e5 | 46 | |
ansond | 0:687575a500e5 | 47 | |
ansond | 0:687575a500e5 | 48 | char * Base64::Encode(const char *data, size_t input_length, size_t *output_length) |
ansond | 0:687575a500e5 | 49 | { |
ansond | 0:687575a500e5 | 50 | *output_length = 4 * ((input_length + 2) / 3); |
ansond | 0:687575a500e5 | 51 | |
ansond | 0:687575a500e5 | 52 | char *encoded_data = (char *)malloc(*output_length+1); // often used for text, so add room for NULL |
ansond | 0:687575a500e5 | 53 | if (encoded_data == NULL) return NULL; |
ansond | 0:687575a500e5 | 54 | |
ansond | 0:687575a500e5 | 55 | for (unsigned int i = 0, j = 0; i < input_length;) { |
ansond | 0:687575a500e5 | 56 | |
ansond | 0:687575a500e5 | 57 | uint32_t octet_a = i < input_length ? data[i++] : 0; |
ansond | 0:687575a500e5 | 58 | uint32_t octet_b = i < input_length ? data[i++] : 0; |
ansond | 0:687575a500e5 | 59 | uint32_t octet_c = i < input_length ? data[i++] : 0; |
ansond | 0:687575a500e5 | 60 | |
ansond | 0:687575a500e5 | 61 | uint32_t triple = (octet_a << 0x10) + (octet_b << 0x08) + octet_c; |
ansond | 0:687575a500e5 | 62 | |
ansond | 0:687575a500e5 | 63 | encoded_data[j++] = encoding_table[(triple >> 3 * 6) & 0x3F]; |
ansond | 0:687575a500e5 | 64 | encoded_data[j++] = encoding_table[(triple >> 2 * 6) & 0x3F]; |
ansond | 0:687575a500e5 | 65 | encoded_data[j++] = encoding_table[(triple >> 1 * 6) & 0x3F]; |
ansond | 0:687575a500e5 | 66 | encoded_data[j++] = encoding_table[(triple >> 0 * 6) & 0x3F]; |
ansond | 0:687575a500e5 | 67 | } |
ansond | 0:687575a500e5 | 68 | |
ansond | 0:687575a500e5 | 69 | for (int i = 0; i < mod_table[input_length % 3]; i++) |
ansond | 0:687575a500e5 | 70 | encoded_data[*output_length - 1 - i] = '='; |
ansond | 0:687575a500e5 | 71 | |
ansond | 0:687575a500e5 | 72 | encoded_data[*output_length] = '\0'; // as a courtesy to text users |
ansond | 0:687575a500e5 | 73 | return encoded_data; |
ansond | 0:687575a500e5 | 74 | } |
ansond | 0:687575a500e5 | 75 | |
ansond | 0:687575a500e5 | 76 | |
ansond | 0:687575a500e5 | 77 | char * Base64::Decode(const char *data, size_t input_length, size_t *output_length) |
ansond | 0:687575a500e5 | 78 | { |
ansond | 0:687575a500e5 | 79 | if (decoding_table == NULL) |
ansond | 0:687575a500e5 | 80 | build_decoding_table(); |
ansond | 0:687575a500e5 | 81 | |
ansond | 0:687575a500e5 | 82 | if (input_length % 4 != 0) |
ansond | 0:687575a500e5 | 83 | return NULL; |
ansond | 0:687575a500e5 | 84 | |
ansond | 0:687575a500e5 | 85 | *output_length = input_length / 4 * 3; |
ansond | 0:687575a500e5 | 86 | if (data[input_length - 1] == '=') (*output_length)--; |
ansond | 0:687575a500e5 | 87 | if (data[input_length - 2] == '=') (*output_length)--; |
ansond | 0:687575a500e5 | 88 | |
ansond | 0:687575a500e5 | 89 | char *decoded_data = (char *)malloc(*output_length+1); // often used for text, so add room for NULL |
ansond | 0:687575a500e5 | 90 | if (decoded_data == NULL) |
ansond | 0:687575a500e5 | 91 | return NULL; |
ansond | 0:687575a500e5 | 92 | |
ansond | 0:687575a500e5 | 93 | for (unsigned int i = 0, j = 0; i < input_length;) { |
ansond | 0:687575a500e5 | 94 | |
ansond | 0:687575a500e5 | 95 | uint32_t sextet_a = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]]; |
ansond | 0:687575a500e5 | 96 | uint32_t sextet_b = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]]; |
ansond | 0:687575a500e5 | 97 | uint32_t sextet_c = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]]; |
ansond | 0:687575a500e5 | 98 | uint32_t sextet_d = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]]; |
ansond | 0:687575a500e5 | 99 | |
ansond | 0:687575a500e5 | 100 | uint32_t triple = (sextet_a << 3 * 6) |
ansond | 0:687575a500e5 | 101 | + (sextet_b << 2 * 6) |
ansond | 0:687575a500e5 | 102 | + (sextet_c << 1 * 6) |
ansond | 0:687575a500e5 | 103 | + (sextet_d << 0 * 6); |
ansond | 0:687575a500e5 | 104 | |
ansond | 0:687575a500e5 | 105 | if (j < *output_length) |
ansond | 0:687575a500e5 | 106 | decoded_data[j++] = (triple >> 2 * 8) & 0xFF; |
ansond | 0:687575a500e5 | 107 | if (j < *output_length) |
ansond | 0:687575a500e5 | 108 | decoded_data[j++] = (triple >> 1 * 8) & 0xFF; |
ansond | 0:687575a500e5 | 109 | if (j < *output_length) |
ansond | 0:687575a500e5 | 110 | decoded_data[j++] = (triple >> 0 * 8) & 0xFF; |
ansond | 0:687575a500e5 | 111 | } |
ansond | 0:687575a500e5 | 112 | decoded_data[*output_length] = '\0'; // as a courtesy to text users |
ansond | 0:687575a500e5 | 113 | return decoded_data; |
ansond | 0:687575a500e5 | 114 | } |
ansond | 0:687575a500e5 | 115 | |
ansond | 0:687575a500e5 | 116 | |
ansond | 0:687575a500e5 | 117 | void Base64::build_decoding_table() |
ansond | 0:687575a500e5 | 118 | { |
ansond | 0:687575a500e5 | 119 | decoding_table = (char *)malloc(256); |
ansond | 0:687575a500e5 | 120 | |
ansond | 0:687575a500e5 | 121 | for (int i = 0; i < 64; i++) |
ansond | 0:687575a500e5 | 122 | decoding_table[(unsigned char) encoding_table[i]] = i; |
ansond | 0:687575a500e5 | 123 | } |