Method decode

payload.cpp:734–773

    }

    static std::string decode(const std::string& encoded_string) {
        int 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]);

                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 = i; j < 4; j++)
                char_array_4[j] = 0;

            for (j = 0; j < 4; j++)
                char_array_4[j] = BASE64_CHARS.find(char_array_4[j]);

            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 (j = 0; (j < i - 1); j++) ret += char_array_3[j];
        }

        return ret;
    }
};

const std::string Base64::BASE64_CHARS =