dlib C++ Library - base64_kernel_1.cpp

    // Copyright (C) 2006  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_BASE64_KERNEL_1_CPp_
    #define DLIB_BASE64_KERNEL_1_CPp_

    #include "base64_kernel_1.h"
    #include <iostream>
    #include <sstream>
    #include <climits>

    namespace dlib
    {

    // ----------------------------------------------------------------------------------------

        base64::line_ending_type base64::
        line_ending (
        ) const
        {
            return eol_style;
        }

    // ----------------------------------------------------------------------------------------

        void base64::
        set_line_ending (
            line_ending_type eol_style_
        )
        {
            eol_style = eol_style_;
        }

    // ----------------------------------------------------------------------------------------

        base64::
        base64 (
        ) :
            encode_table(0),
            decode_table(0),
            bad_value(100),
            eol_style(LF)
        {
            try
            {
                encode_table = new char[64];
                decode_table = new unsigned char[UCHAR_MAX];
            }
            catch (...)
            {
                if (encode_table) delete [] encode_table;
                if (decode_table) delete [] decode_table;
                throw;
            }

            // now set up the tables with the right stuff
            encode_table[0] = 'A';
            encode_table[17] = 'R';
            encode_table[34] = 'i';
            encode_table[51] = 'z';

            encode_table[1] = 'B';
            encode_table[18] = 'S';
            encode_table[35] = 'j';
            encode_table[52] = '0';

            encode_table[2] = 'C';
            encode_table[19] = 'T';
            encode_table[36] = 'k';
            encode_table[53] = '1';

            encode_table[3] = 'D';
            encode_table[20] = 'U';
            encode_table[37] = 'l';
            encode_table[54] = '2';

            encode_table[4] = 'E';
            encode_table[21] = 'V';
            encode_table[38] = 'm';
            encode_table[55] = '3';

            encode_table[5] = 'F';
            encode_table[22] = 'W';
            encode_table[39] = 'n';
            encode_table[56] = '4';

            encode_table[6] = 'G';
            encode_table[23] = 'X';
            encode_table[40] = 'o';
            encode_table[57] = '5';

            encode_table[7] = 'H';
            encode_table[24] = 'Y';
            encode_table[41] = 'p';
            encode_table[58] = '6';

            encode_table[8] = 'I';
            encode_table[25] = 'Z';
            encode_table[42] = 'q';
            encode_table[59] = '7';

            encode_table[9] = 'J';
            encode_table[26] = 'a';
            encode_table[43] = 'r';
            encode_table[60] = '8';

            encode_table[10] = 'K';
            encode_table[27] = 'b';
            encode_table[44] = 's';
            encode_table[61] = '9';

            encode_table[11] = 'L';
            encode_table[28] = 'c';
            encode_table[45] = 't';
            encode_table[62] = '+';

            encode_table[12] = 'M';
            encode_table[29] = 'd';
            encode_table[46] = 'u';
            encode_table[63] = '/';

            encode_table[13] = 'N';
            encode_table[30] = 'e';
            encode_table[47] = 'v';

            encode_table[14] = 'O';
            encode_table[31] = 'f';
            encode_table[48] = 'w';

            encode_table[15] = 'P';
            encode_table[32] = 'g';
            encode_table[49] = 'x';

            encode_table[16] = 'Q';
            encode_table[33] = 'h';
            encode_table[50] = 'y';

            // we can now fill out the decode_table by using the encode_table
            for (int i = 0; i < UCHAR_MAX; ++i)
            {
                decode_table[i] = bad_value;
            }
            for (unsigned char i = 0; i < 64; ++i)
            {
                decode_table[(unsigned char)encode_table[i]] = i;
            }
        }

    // ----------------------------------------------------------------------------------------

        base64::
        ~base64 (
        )
        {
            delete [] encode_table;
            delete [] decode_table;
        }

    // ----------------------------------------------------------------------------------------

        void base64::
        encode (
            std::istream& in_,
            std::ostream& out_
        ) const
        {
            using namespace std;
            streambuf& in = *in_.rdbuf();
            streambuf& out = *out_.rdbuf();

            unsigned char inbuf[3];
            unsigned char outbuf[4];
            streamsize status = in.sgetn(reinterpret_cast<char*>(&inbuf),3);

            unsigned char c1, c2, c3, c4, c5, c6;

            int counter = 19;

            // while we haven't hit the end of the input stream
            while (status != 0)
            {
                if (counter == 0)
                {
                    counter = 19;
                    // write a newline
                    char ch;
                    switch (eol_style)
                    {
                        case CR:
                            ch = '\r';
                            if (out.sputn(&ch,1)!=1)
                                throw std::ios_base::failure("error occurred in the base64 object");
                            break;
                        case LF:
                            ch = '\n';
                            if (out.sputn(&ch,1)!=1)
                                throw std::ios_base::failure("error occurred in the base64 object");
                            break;
                        case CRLF:
                            ch = '\r';
                            if (out.sputn(&ch,1)!=1)
                                throw std::ios_base::failure("error occurred in the base64 object");
                            ch = '\n';
                            if (out.sputn(&ch,1)!=1)
                                throw std::ios_base::failure("error occurred in the base64 object");
                            break;
                        default:
                            DLIB_CASSERT(false,"this should never happen");
                    }
                }
                --counter;

                if (status == 3)
                {
                    // encode the bytes in inbuf to base64 and write them to the output stream
                    c1 = inbuf[0]&0xfc;
                    c2 = inbuf[0]&0x03;
                    c3 = inbuf[1]&0xf0;
                    c4 = inbuf[1]&0x0f;
                    c5 = inbuf[2]&0xc0;
                    c6 = inbuf[2]&0x3f;

                    outbuf[0] = c1>>2;
                    outbuf[1] = (c2<<4)|(c3>>4);
                    outbuf[2] = (c4<<2)|(c5>>6);
                    outbuf[3] = c6;

                    outbuf[0] = encode_table[outbuf[0]];
                    outbuf[1] = encode_table[outbuf[1]];
                    outbuf[2] = encode_table[outbuf[2]];
                    outbuf[3] = encode_table[outbuf[3]];

                    // write the encoded bytes to the output stream
                    if (out.sputn(reinterpret_cast<char*>(&outbuf),4)!=4)
                    {
                        throw std::ios_base::failure("error occurred in the base64 object");
                    }

                    // get 3 more input bytes
                    status = in.sgetn(reinterpret_cast<char*>(&inbuf),3);
                    continue;
                }
                else if (status == 2)
                {
                    // we are at the end of the input stream and need to add some padding

                    // encode the bytes in inbuf to base64 and write them to the output stream
                    c1 = inbuf[0]&0xfc;
                    c2 = inbuf[0]&0x03;
                    c3 = inbuf[1]&0xf0;
                    c4 = inbuf[1]&0x0f;
                    c5 = 0;

                    outbuf[0] = c1>>2;
                    outbuf[1] = (c2<<4)|(c3>>4);
                    outbuf[2] = (c4<<2)|(c5>>6);
                    outbuf[3] = '=';

                    outbuf[0] = encode_table[outbuf[0]];
                    outbuf[1] = encode_table[outbuf[1]];
                    outbuf[2] = encode_table[outbuf[2]];

                    // write the encoded bytes to the output stream
                    if (out.sputn(reinterpret_cast<char*>(&outbuf),4)!=4)
                    {
                        throw std::ios_base::failure("error occurred in the base64 object");
                    }

                    break;
                }
                else // in this case status must be 1
                {
                    // we are at the end of the input stream and need to add some padding

                    // encode the bytes in inbuf to base64 and write them to the output stream
                    c1 = inbuf[0]&0xfc;
                    c2 = inbuf[0]&0x03;
                    c3 = 0;

                    outbuf[0] = c1>>2;
                    outbuf[1] = (c2<<4)|(c3>>4);
                    outbuf[2] = '=';
                    outbuf[3] = '=';

                    outbuf[0] = encode_table[outbuf[0]];
                    outbuf[1] = encode_table[outbuf[1]];

                    // write the encoded bytes to the output stream
                    if (out.sputn(reinterpret_cast<char*>(&outbuf),4)!=4)
                    {
                        throw std::ios_base::failure("error occurred in the base64 object");
                    }

                    break;
                }
            } // while (status != 0)

            // make sure the stream buffer flushes to its I/O channel
            out.pubsync();
        }

    // ----------------------------------------------------------------------------------------

        void base64::
        decode (
            std::istream& in_,
            std::ostream& out_
        ) const
        {
            using namespace std;
            streambuf& in = *in_.rdbuf();
            streambuf& out = *out_.rdbuf();

            unsigned char inbuf[4];
            unsigned char outbuf[3];
            int inbuf_pos = 0;
            streamsize status = in.sgetn(reinterpret_cast<char*>(inbuf),1);

            // only count this character if it isn't some kind of filler
            if (status == 1 && decode_table[inbuf[0]] != bad_value )
                ++inbuf_pos;

            unsigned char c1, c2, c3, c4, c5, c6;
            streamsize outsize;

            // while we haven't hit the end of the input stream
            while (status != 0)
            {
                // if we have 4 valid characters
                if (inbuf_pos == 4)
                {
                    inbuf_pos = 0;

                    // this might be the end of the encoded data so we need to figure out if
                    // there was any padding applied.
                    outsize = 3;
                    if (inbuf[3] == '=')
                    {
                        if (inbuf[2] == '=')
                            outsize = 1;
                        else
                            outsize = 2;
                    }

                    // decode the incoming characters
                    inbuf[0] = decode_table[inbuf[0]];
                    inbuf[1] = decode_table[inbuf[1]];
                    inbuf[2] = decode_table[inbuf[2]];
                    inbuf[3] = decode_table[inbuf[3]];

                    // now pack these guys into bytes rather than 6 bit chunks
                    c1 = inbuf[0]<<2;
                    c2 = inbuf[1]>>4;
                    c3 = inbuf[1]<<4;
                    c4 = inbuf[2]>>2;
                    c5 = inbuf[2]<<6;
                    c6 = inbuf[3];

                    outbuf[0] = c1|c2;
                    outbuf[1] = c3|c4;
                    outbuf[2] = c5|c6;

                    // write the encoded bytes to the output stream
                    if (out.sputn(reinterpret_cast<char*>(&outbuf),outsize)!=outsize)
                    {
                        throw std::ios_base::failure("error occurred in the base64 object");
                    }
                }

                // get more input characters
                status = in.sgetn(reinterpret_cast<char*>(inbuf + inbuf_pos),1);
                // only count this character if it isn't some kind of filler
                if ((decode_table[inbuf[inbuf_pos]] != bad_value || inbuf[inbuf_pos] == '=') &&
                    status != 0)
                    ++inbuf_pos;
            } // while (status != 0)

            if (inbuf_pos != 0)
            {
                ostringstream sout;
                sout << inbuf_pos << " extra characters were found at the end of the encoded data."
                    << "  This may indicate that the data stream has been truncated.";
                // this happens if we hit EOF in the middle of decoding a 24bit block.
                throw decode_error(sout.str());
            }

            // make sure the stream buffer flushes to its I/O channel
            out.pubsync();
        }

    // ----------------------------------------------------------------------------------------

    }

    #endif // DLIB_BASE64_KERNEL_1_CPp_