Base64 library borrowed from HTTPServer implementation...
Diff: Base64.cpp
- Revision:
- 0:687575a500e5
- Child:
- 1:4920bc5699f3
diff -r 000000000000 -r 687575a500e5 Base64.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Base64.cpp Thu Dec 18 03:59:35 2014 +0000 @@ -0,0 +1,123 @@ +// +// Base64 Encoding and Decoding +// +// @note Copyright © 2013 by Smartware Computing, all rights reserved. +// Individuals may use this application for evaluation or non-commercial +// purposes. Within this restriction, changes may be made to this application +// as long as this copyright notice is retained. The user shall make +// clear that their work is a derived work, and not the original. +// Users of this application and sources accept this application "as is" and +// shall hold harmless Smartware Computing, for any undesired results while +// using this application - whether real or imagined. +// +// author David Smart, Smartware Computing +// +#ifndef WIN32 +#include "mbed.h" +#else +#include "windows.h" +typedef unsigned int uint32_t; +#endif +#include "Base64.h" + +static const char encoding_table[] = { + 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', + 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', + 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', + 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', + 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', + 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', + 'w', 'x', 'y', 'z', '0', '1', '2', '3', + '4', '5', '6', '7', '8', '9', '+', '/' +}; + +static const int mod_table[] = {0, 2, 1}; + +Base64::Base64() +{ + decoding_table = NULL; +} + +Base64::~Base64() +{ + if (decoding_table) + free(decoding_table); +} + + +char * Base64::Encode(const char *data, size_t input_length, size_t *output_length) +{ + *output_length = 4 * ((input_length + 2) / 3); + + char *encoded_data = (char *)malloc(*output_length+1); // often used for text, so add room for NULL + if (encoded_data == NULL) return NULL; + + for (unsigned int i = 0, j = 0; i < input_length;) { + + uint32_t octet_a = i < input_length ? data[i++] : 0; + uint32_t octet_b = i < input_length ? data[i++] : 0; + uint32_t octet_c = i < input_length ? data[i++] : 0; + + uint32_t triple = (octet_a << 0x10) + (octet_b << 0x08) + octet_c; + + encoded_data[j++] = encoding_table[(triple >> 3 * 6) & 0x3F]; + encoded_data[j++] = encoding_table[(triple >> 2 * 6) & 0x3F]; + encoded_data[j++] = encoding_table[(triple >> 1 * 6) & 0x3F]; + encoded_data[j++] = encoding_table[(triple >> 0 * 6) & 0x3F]; + } + + for (int i = 0; i < mod_table[input_length % 3]; i++) + encoded_data[*output_length - 1 - i] = '='; + + encoded_data[*output_length] = '\0'; // as a courtesy to text users + return encoded_data; +} + + +char * Base64::Decode(const char *data, size_t input_length, size_t *output_length) +{ + if (decoding_table == NULL) + build_decoding_table(); + + if (input_length % 4 != 0) + return NULL; + + *output_length = input_length / 4 * 3; + if (data[input_length - 1] == '=') (*output_length)--; + if (data[input_length - 2] == '=') (*output_length)--; + + char *decoded_data = (char *)malloc(*output_length+1); // often used for text, so add room for NULL + if (decoded_data == NULL) + return NULL; + + for (unsigned int i = 0, j = 0; i < input_length;) { + + uint32_t sextet_a = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]]; + uint32_t sextet_b = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]]; + uint32_t sextet_c = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]]; + uint32_t sextet_d = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]]; + + uint32_t triple = (sextet_a << 3 * 6) + + (sextet_b << 2 * 6) + + (sextet_c << 1 * 6) + + (sextet_d << 0 * 6); + + if (j < *output_length) + decoded_data[j++] = (triple >> 2 * 8) & 0xFF; + if (j < *output_length) + decoded_data[j++] = (triple >> 1 * 8) & 0xFF; + if (j < *output_length) + decoded_data[j++] = (triple >> 0 * 8) & 0xFF; + } + decoded_data[*output_length] = '\0'; // as a courtesy to text users + return decoded_data; +} + + +void Base64::build_decoding_table() +{ + decoding_table = (char *)malloc(256); + + for (int i = 0; i < 64; i++) + decoding_table[(unsigned char) encoding_table[i]] = i; +}