base64encode.hpp

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/*
* Base64 encoding/decoding (RFC1341)
* Copyright (c) 2005-2011, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
 
// 2016-12-12 - Gaspard Petit : Slightly modified to return a std::string 
// instead of a buffer allocated with malloc.
 
#include <string>
 
static const unsigned char base64_table[65] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
std::string base64_encode(const char* src, size_t len) {
    char* out, * pos;
    const char* end, * in;
 
    size_t olen;
 
    olen = 4 * ((len + 2) / 3); /* 3-byte blocks to 4-byte */
 
    if(olen < len)
        return std::string(); /* integer overflow */
 
    std::string outStr;
    outStr.resize(olen);
    out = (char*)&outStr[0];
 
    end = src + len;
    in = src;
    pos = out;
    while(end - in >= 3) {
        *pos++ = base64_table[in[0] >> 2];
        *pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
        *pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
        *pos++ = base64_table[in[2] & 0x3f];
        in += 3;
    }
 
    if(end - in) {
        *pos++ = base64_table[in[0] >> 2];
        if(end - in == 1) {
            *pos++ = base64_table[(in[0] & 0x03) << 4];
            *pos++ = '=';
        } else {
            *pos++ = base64_table[((in[0] & 0x03) << 4) |
                (in[1] >> 4)];
            *pos++ = base64_table[(in[1] & 0x0f) << 2];
        }
        *pos++ = '=';
    }
 
    return outStr;
}