base64.cpp

00001 #include "base64.h"
00002 
00003 const char *base64::szB64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
00004 
00005 base64::base64() : lpszOutputString(NULL)
00006 {
00007 }
00008 
00009 base64::~base64()
00010 {
00011     if(lpszOutputString)
00012         delete[] lpszOutputString;
00013 }
00014 
00015 const char *base64::Encode(const char *szStr, int iLens)
00016 {
00017     int i,j;
00018 
00019     if(lpszOutputString)
00020         delete[] lpszOutputString;
00021 
00022     if(iLens == -1)
00023         iLen = strlen(szStr);
00024     else
00025         iLen = iLens;
00026 
00027     lpszOutputString =
00028         new char[(int)((double)(iLen)*1.5)+10];
00029     for(i = 0,j = 0; i < (iLen - (iLen % 3)); i+=3)
00030     {
00031         lpszOutputString[j] = szB64[(szStr[i] & 0xfc) >> 2];
00032         lpszOutputString[j+1] = szB64[((szStr[i] &0x03) << 4) |
00033                                     ((szStr[i+1] & 0xf0) >> 4)];
00034         lpszOutputString[j+2] = szB64[((szStr[i+1] & 0x0f) <<2 ) |
00035                                     ((szStr[i+2] & 0xc0) >> 6)];
00036         lpszOutputString[j+3] = szB64[(szStr[i+2] & 0x3f)];
00037         j += 4;
00038     }
00039     i = iLen-(iLen % 3);    // 残りのサイズを計算
00040     switch(iLen % 3)
00041     {
00042     case 2: // 1文字分パディングが必要
00043     {
00044         lpszOutputString[j] = szB64[(szStr[i] & 0xfc) >> 2];
00045         lpszOutputString[j+1] = szB64[((szStr[i] &0x03) << 4) |
00046                                     ((szStr[i+1] & 0xf0) >> 4)];
00047         lpszOutputString[j+2] = szB64[((szStr[i+1] & 0x0f) <<2 )];
00048         lpszOutputString[j+3] = szB64[64];  // Pad
00049         lpszOutputString[j+4] = '\0';
00050     }
00051     break;
00052     case 1: // 2文字分パディングが必要
00053     {
00054         lpszOutputString[j] = szB64[(szStr[i] & 0xfc) >> 2];
00055         lpszOutputString[j+1] = szB64[((szStr[i] &0x03) << 4)];
00056         lpszOutputString[j+2] = szB64[64];  // Pad
00057         lpszOutputString[j+3] = szB64[64];  // Pad
00058         lpszOutputString[j+4] = '\0';
00059     }
00060     break;
00061     }
00062     lpszOutputString[j+4] = '\0';
00063 
00064     return lpszOutputString;
00065 }
00066 
00067 void base64::Encode(istream& istr, ostream& ostr, int iRet)
00068 {
00069     int i;
00070     char c[3];
00071 
00072     i = 0;
00073     while(!istr.eof())
00074     {
00075         c[0] = c[1] = c[2] = '\0';
00076         istr.read(c,3);
00077 
00078         ostr << szB64[(c[0] & 0xfc) >> 2];
00079         i++;    if(i >= iRet && iRet != -1){ ostr << endl; i = 0; }
00080         ostr << szB64[((c[0] &0x03) << 4) | ((c[1] & 0xf0) >> 4)];
00081         i++;    if(i >= iRet && iRet != -1){ ostr << endl; i = 0; }
00082         if(istr.gcount() == 1)
00083             ostr << szB64[64];
00084         else
00085             ostr << szB64[((c[1] & 0x0f) <<2 ) | ((c[2] & 0xc0) >> 6)];
00086         i++;    if(i >= iRet && iRet != -1){ ostr << endl; i = 0; }
00087         if(istr.gcount() == 3)
00088             ostr << szB64[(c[2] & 0x3f)];
00089         else
00090             ostr << szB64[64];
00091         i++;    if(i >= iRet && iRet != -1){ ostr << endl; i = 0; }
00092     }
00093     ostr.flush();
00094 }
00095 
00096 
00097 int base64::FindIndexInB64(char c)
00098 {
00099     int index = 0;
00100     while(szB64[index] != '\0' && szB64[index] != c)
00101         index++;
00102 
00103     if(szB64[index] == '\0')
00104         return -1;  // 見つからず
00105 
00106     return index;   // 見つかった。
00107 }
00108 
00109 const char *base64::Decode(const char *szStr)
00110 {
00111     //lpszOutputString
00112     int i, j, l,iWriteCount,len;
00113     char c;
00114     char buf[4];
00115 
00116     len = iLen = strlen(szStr);
00117     if(lpszOutputString)
00118         delete[] lpszOutputString;
00119 
00120     iLen = (int)(((double)(iLen)/4.0)*3.0) + 4;
00121 
00122     lpszOutputString = new char[iLen];
00123 
00124     for(i = 0, j = 0; i < len; i+=4)
00125     {
00126         iWriteCount = 3;
00127         for(l = 0; l < 4 && i+l<len; l++)
00128         {
00129             c = szStr[i+l];
00130             if(c == szB64[64])  // Pad
00131                 iWriteCount--;
00132             else {
00133                 buf[l] = FindIndexInB64(c);
00134                 //if(buf[l] == -1) error!;
00135             }
00136         }
00137         lpszOutputString[j] = ((buf[0] << 2) & 0xfc) | ((buf[1] >> 4) & 0x03);
00138         if(iWriteCount >= 2)
00139             lpszOutputString[j+1] = ((buf[1] << 4) & 0xf0) | ((buf[2] >> 2) & 0x0f);
00140         if(iWriteCount == 3)
00141             lpszOutputString[j+2] = ((buf[2] << 6) & 0xc0) | (buf[3] & 0x3f);
00142         j+=iWriteCount;
00143     }
00144     iLen = j;
00145     lpszOutputString[j] = '\0';
00146 
00147     return lpszOutputString;
00148 }
00149 
00150 void base64::Decode(istream& istr, ostream& ostr)
00151 {
00152     int i,iWriteCount;
00153     char c;
00154     char buf[4];
00155     char out[3];
00156 
00157     while(1)
00158     {
00159         iWriteCount = 3;
00160         for(i = 0; i < 4; i++)
00161         {
00162             istr >> c;
00163             if(istr.eof())
00164             {
00165                 ostr.flush();
00166                 return;
00167             }
00168             if(c == szB64[64])  // Pad
00169                 iWriteCount--;
00170             else {
00171                 buf[i] = FindIndexInB64(c);
00172                 //if(buf[i] == -1) error!;
00173             }
00174         }
00175         out[0] = ((buf[0] << 2) & 0xfc) | ((buf[1] >> 4) & 0x03);
00176         out[1] = ((buf[1] << 4) & 0xf0) | ((buf[2] >> 2) & 0x0f);
00177         out[2] = ((buf[2] << 6) & 0xc0) | (buf[3] & 0x3f);
00178         ostr.write(out, iWriteCount);
00179     }
00180 }