File content as of revision 4:1354e56c7dd3:

#include "base64.h"

const char *base64::szB64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

base64::base64() : lpszOutputString(NULL)
{
}

base64::~base64()
{
    if(lpszOutputString)
        delete[] lpszOutputString;
}

const char *base64::Encode(const char *szStr, int iLens)
{
    int i,j;

    if(lpszOutputString)
        delete[] lpszOutputString;

    if(iLens == -1)
        iLen = strlen(szStr);
    else
        iLen = iLens;

    lpszOutputString =
        new char[(int)((double)(iLen)*1.5)+10];
    for(i = 0,j = 0; i < (iLen - (iLen % 3)); i+=3)
    {
        lpszOutputString[j] = szB64[(szStr[i] & 0xfc) >> 2];
        lpszOutputString[j+1] = szB64[((szStr[i] &0x03) << 4) |
                                    ((szStr[i+1] & 0xf0) >> 4)];
        lpszOutputString[j+2] = szB64[((szStr[i+1] & 0x0f) <<2 ) |
                                    ((szStr[i+2] & 0xc0) >> 6)];
        lpszOutputString[j+3] = szB64[(szStr[i+2] & 0x3f)];
        j += 4;
    }
    i = iLen-(iLen % 3);    // 残りのサイズを計算
    switch(iLen % 3)
    {
    case 2: // 1文字分パディングが必要
    {
        lpszOutputString[j] = szB64[(szStr[i] & 0xfc) >> 2];
        lpszOutputString[j+1] = szB64[((szStr[i] &0x03) << 4) |
                                    ((szStr[i+1] & 0xf0) >> 4)];
        lpszOutputString[j+2] = szB64[((szStr[i+1] & 0x0f) <<2 )];
        lpszOutputString[j+3] = szB64[64];  // Pad
        lpszOutputString[j+4] = '\0';
    }
    break;
    case 1: // 2文字分パディングが必要
    {
        lpszOutputString[j] = szB64[(szStr[i] & 0xfc) >> 2];
        lpszOutputString[j+1] = szB64[((szStr[i] &0x03) << 4)];
        lpszOutputString[j+2] = szB64[64];  // Pad
        lpszOutputString[j+3] = szB64[64];  // Pad
        lpszOutputString[j+4] = '\0';
    }
    break;
    }
    lpszOutputString[j+4] = '\0';

    return lpszOutputString;
}

void base64::Encode(istream& istr, ostream& ostr, int iRet)
{
    int i;
    char c[3];

    i = 0;
    while(!istr.eof())
    {
        c[0] = c[1] = c[2] = '\0';
        istr.read(c,3);

        ostr << szB64[(c[0] & 0xfc) >> 2];
        i++;    if(i >= iRet && iRet != -1){ ostr << endl; i = 0; }
        ostr << szB64[((c[0] &0x03) << 4) | ((c[1] & 0xf0) >> 4)];
        i++;    if(i >= iRet && iRet != -1){ ostr << endl; i = 0; }
        if(istr.gcount() == 1)
            ostr << szB64[64];
        else
            ostr << szB64[((c[1] & 0x0f) <<2 ) | ((c[2] & 0xc0) >> 6)];
        i++;    if(i >= iRet && iRet != -1){ ostr << endl; i = 0; }
        if(istr.gcount() == 3)
            ostr << szB64[(c[2] & 0x3f)];
        else
            ostr << szB64[64];
        i++;    if(i >= iRet && iRet != -1){ ostr << endl; i = 0; }
    }
    ostr.flush();
}


int base64::FindIndexInB64(char c)
{
    int index = 0;
    while(szB64[index] != '\0' && szB64[index] != c)
        index++;

    if(szB64[index] == '\0')
        return -1;  // 見つからず

    return index;   // 見つかった。
}

const char *base64::Decode(const char *szStr)
{
    //lpszOutputString
    int i, j, l,iWriteCount,len;
    char c;
    char buf[4];

    len = iLen = strlen(szStr);
    if(lpszOutputString)
        delete[] lpszOutputString;

    iLen = (int)(((double)(iLen)/4.0)*3.0) + 4;

    lpszOutputString = new char[iLen];

    for(i = 0, j = 0; i < len; i+=4)
    {
        iWriteCount = 3;
        for(l = 0; l < 4 && i+l<len; l++)
        {
            c = szStr[i+l];
            if(c == szB64[64])  // Pad
                iWriteCount--;
            else {
                buf[l] = FindIndexInB64(c);
                //if(buf[l] == -1) error!;
            }
        }
        lpszOutputString[j] = ((buf[0] << 2) & 0xfc) | ((buf[1] >> 4) & 0x03);
        if(iWriteCount >= 2)
            lpszOutputString[j+1] = ((buf[1] << 4) & 0xf0) | ((buf[2] >> 2) & 0x0f);
        if(iWriteCount == 3)
            lpszOutputString[j+2] = ((buf[2] << 6) & 0xc0) | (buf[3] & 0x3f);
        j+=iWriteCount;
    }
    iLen = j;
    lpszOutputString[j] = '\0';

    return lpszOutputString;
}

void base64::Decode(istream& istr, ostream& ostr)
{
    int i,iWriteCount;
    char c;
    char buf[4];
    char out[3];

    while(1)
    {
        iWriteCount = 3;
        for(i = 0; i < 4; i++)
        {
            istr >> c;
            if(istr.eof())
            {
                ostr.flush();
                return;
            }
            if(c == szB64[64])  // Pad
                iWriteCount--;
            else {
                buf[i] = FindIndexInB64(c);
                //if(buf[i] == -1) error!;
            }
        }
        out[0] = ((buf[0] << 2) & 0xfc) | ((buf[1] >> 4) & 0x03);
        out[1] = ((buf[1] << 4) & 0xf0) | ((buf[2] >> 2) & 0x0f);
        out[2] = ((buf[2] << 6) & 0xc0) | (buf[3] & 0x3f);
        ostr.write(out, iWriteCount);
    }
}