base64.h

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#ifndef _BASE64_H_
#define _BASE64_H_

#include <iostream>
#include <string>
#include <vector>
using namespace std;

namespace bridges {
    typedef unsigned char BYTE;


    namespace base64 {

        const string base64_chars =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            "abcdefghijklmnopqrstuvwxyz"
            "0123456789+/";


        inline bool is_base64(BYTE c) {
            return (isalnum(c) || (c == '+') || (c == '/'));
        }

        string inline encode(BYTE const* buf, unsigned int bufLen) {
            string ret;
            int i = 0;
            int j = 0;
            BYTE char_array_3[3];
            BYTE char_array_4[4];

            while (bufLen--) {
                // 3 chars become 4 chars in base 64 representation
                // hence the char arrays of 3 and 4
                char_array_3[i++] = *(buf++);
                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;
                }
            }

            // handle any left over bytes, by padding with end of string chars
            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);
                char_array_4[3] = char_array_3[2] & 0x3f;

                for (j = 0; (j < i + 1); j++)
                    ret += base64_chars[char_array_4[j]];

                // not sure what this does!
                while ((i++ < 3))
                    ret += '=';
            }

            return ret;
        }

        vector<BYTE> inline decode(string const& encoded_string) {
            size_t in_len = encoded_string.size();
            int i = 0;
            //  int j = 0;
            int in_ = 0;
            BYTE char_array_4[4], char_array_3[3];
            vector<BYTE> 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] = (BYTE) 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.push_back(char_array_3[i]);
                    i = 0;
                }
            }

            if (i) {
                for (int j = i; j < 4; j++)
                    char_array_4[j] = 0;

                for (int j = 0; j < 4; j++)
                    char_array_4[j] = (BYTE) 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 (int j = 0; (j < i - 1); j++)
                    ret.push_back(char_array_3[j]);
            }

            return ret;
        }

    } // end namespace base64
}  // end namespace bridges

#endif