Base64.hpp

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//
// Created by robin on 22.03.2020.
// Based on: https://github.com/ReneNyffenegger/cpp-base64
//
 
#ifndef TILESON_BASE64_HPP
#define TILESON_BASE64_HPP
#include <string>
#include <iostream>
 
namespace tson
{
    class Base64
    {
        public:
            inline static std::string Encode(unsigned char const *, unsigned int len);
 
            inline static std::string Decode(std::string const &s);
 
    };
 
    static const std::string base64_chars =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            "abcdefghijklmnopqrstuvwxyz"
            "0123456789+/";
 
    static inline bool is_base64(unsigned char c)
    {
        return (isalnum(c) || (c == '+') || (c == '/'));
    }
}
 
std::string tson::Base64::Encode(unsigned char const* bytes_to_encode, unsigned int in_len) {
    std::string ret;
    int i = 0;
    int j = 0;
    unsigned char char_array_3[3];
    unsigned char char_array_4[4];
 
    while (in_len--) {
        char_array_3[i++] = *(bytes_to_encode++);
        if (i == 3) {
            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;
 
            for(i = 0; (i <4) ; i++)
                ret += base64_chars[char_array_4[i]];
            i = 0;
        }
    }
 
    if (i)
    {
        for(j = i; j < 3; j++)
            char_array_3[j] = '\0';
 
        char_array_4[0] = ( char_array_3[0] & 0xfc) >> 2;
        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
 
        for (j = 0; (j < i + 1); j++)
            ret += base64_chars[char_array_4[j]];
 
        while((i++ < 3))
            ret += '=';
 
    }
 
    return ret;
 
}
 
std::string tson::Base64::Decode(std::string const& encoded_string) {
    size_t in_len = encoded_string.size();
    int i = 0;
    int j = 0;
    int in_ = 0;
    unsigned char char_array_4[4], char_array_3[3];
    std::string ret;
 
    while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
        char_array_4[i++] = encoded_string[in_]; in_++;
        if (i ==4) {
            for (i = 0; i <4; i++)
                char_array_4[i] = base64_chars.find(char_array_4[i]) & 0xff;
 
            char_array_3[0] = ( char_array_4[0] << 2       ) + ((char_array_4[1] & 0x30) >> 4);
            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) +   char_array_4[3];
 
            for (i = 0; (i < 3); i++)
                ret += char_array_3[i];
            i = 0;
        }
    }
 
    if (i) {
        for (j = 0; j < i; j++)
            char_array_4[j] = base64_chars.find(char_array_4[j]) & 0xff;
 
        char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
        char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
 
        for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
    }
 
    return ret;
}
 
#endif //TILESON_BASE64_HPP