src/common/base64.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/base64.cpp
   3 // Purpose:     implementation of BASE64 encoding/decoding functions
   4 // Author:      Charles Reimers, Vadim Zeitlin
   5 // Created:     2007-06-18
   6 // RCS-ID:      $Id$
   7 // Licence:     wxWindows licence
   8 ///////////////////////////////////////////////////////////////////////////////
   9
  10 #include "wx/wxprec.h"
  11
  12 #ifdef __BORLANDC__
  13     #pragma hdrstop
  14 #endif
  15
  16 #if wxUSE_BASE64
  17
  18 #include "wx/base64.h"
  19
  20 size_t
  21 wxBase64Encode(char *dst, size_t dstLen, const void *src_, size_t srcLen)
  22 {
  23     wxCHECK_MSG( src_, wxCONV_FAILED, wxT("NULL input buffer") );
  24
  25     const unsigned char *src = static_cast<const unsigned char *>(src_);
  26
  27     static const char b64[] =
  28         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  29
  30
  31     size_t encLen = 0;
  32
  33     // encode blocks of 3 bytes into 4 base64 characters
  34     for ( ; srcLen >= 3; srcLen -= 3, src += 3 )
  35     {
  36         encLen += 4;
  37         if ( dst )
  38         {
  39             if ( encLen > dstLen )
  40                 return wxCONV_FAILED;
  41
  42             *dst++ = b64[src[0] >> 2];
  43             *dst++ = b64[((src[0] & 0x03) << 4) | ((src[1] & 0xf0) >> 4)];
  44             *dst++ = b64[((src[1] & 0x0f) << 2) | ((src[2] & 0xc0) >> 6)];
  45             *dst++ = b64[src[2] & 0x3f];
  46         }
  47     }
  48
  49     // finish with the remaining characters
  50     if ( srcLen )
  51     {
  52         encLen += 4;
  53         if ( dst )
  54         {
  55             if ( encLen > dstLen )
  56                 return wxCONV_FAILED;
  57
  58             // we have definitely one and maybe two bytes remaining
  59             unsigned char next = srcLen == 2 ? src[1] : 0;
  60             *dst++ = b64[src[0] >> 2];
  61             *dst++ = b64[((src[0] & 0x03) << 4) | ((next & 0xf0) >> 4)];
  62             *dst++ = srcLen == 2 ? b64[((next & 0x0f) << 2)] : '=';
  63             *dst = '=';
  64         }
  65     }
  66
  67     return encLen;
  68 }
  69
  70 size_t
  71 wxBase64Decode(void *dst_, size_t dstLen,
  72                const char *src, size_t srcLen,
  73                wxBase64DecodeMode mode,
  74                size_t *posErr)
  75 {
  76     wxCHECK_MSG( src, wxCONV_FAILED, wxT("NULL input buffer") );
  77
  78     unsigned char *dst = static_cast<unsigned char *>(dst_);
  79
  80     size_t decLen = 0;
  81
  82     if ( srcLen == wxNO_LEN )
  83         srcLen = strlen(src);
  84
  85     // this table contains the values, in base 64, of all valid characters and
  86     // special values WSP or INV for white space and invalid characters
  87     // respectively as well as a special PAD value for '='
  88     enum
  89     {
  90         WSP = 200,
  91         INV,
  92         PAD
  93     };
  94
  95     static const unsigned char decode[256] =
  96     {
  97         WSP,INV,INV,INV,INV,INV,INV,INV,INV,WSP,WSP,INV,WSP,WSP,INV,INV,
  98         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
  99         WSP,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,076,INV,INV,INV,077,
 100         064,065,066,067,070,071,072,073,074,075,INV,INV,INV,PAD,INV,INV,
 101         INV,000,001,002,003,004,005,006,007,010,011,012,013,014,015,016,
 102         017,020,021,022,023,024,025,026,027,030,031,INV,INV,INV,INV,INV,
 103         INV,032,033,034,035,036,037,040,041,042,043,044,045,046,047,050,
 104         051,052,053,054,055,056,057,060,061,062,063,INV,INV,INV,INV,INV,
 105         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 106         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 107         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 108         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 109         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 110         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 111         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 112         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 113     };
 114
 115     // we decode input by groups of 4 characters but things are complicated by
 116     // the fact that there can be whitespace and other junk in it too so keep
 117     // record of where exactly we're inside the current quartet in this var
 118     int n = 0;
 119     unsigned char in[4];                    // current quartet
 120     bool end = false;                       // set when we find padding
 121     size_t padLen = 0;                      // length lost to padding
 122     const char *p;
 123     for ( p = src; srcLen; p++, srcLen-- )
 124     {
 125         const unsigned char c = decode[static_cast<unsigned char>(*p)];
 126         switch ( c )
 127         {
 128             case WSP:
 129                 if ( mode == wxBase64DecodeMode_SkipWS )
 130                     continue;
 131                 // fall through
 132
 133             case INV:
 134                 if ( mode == wxBase64DecodeMode_Relaxed )
 135                     continue;
 136
 137                 // force the loop to stop and an error to be returned
 138                 n = -1;
 139                 srcLen = 1;
 140                 break;
 141
 142             case PAD:
 143                 // set the flag telling us that we're past the end now
 144                 end = true;
 145
 146                 // there can be either a single '=' at the end of a quartet or
 147                 // "==" in positions 2 and 3
 148                 if ( n == 3 )
 149                 {
 150                     padLen = 1;
 151                     in[n++] = '\0';
 152                 }
 153                 else if ( (n == 2) && (--srcLen && *++p == '=') )
 154                 {
 155                     padLen = 2;
 156                     in[n++] = '\0';
 157                     in[n++] = '\0';
 158                 }
 159                 else // invalid padding
 160                 {
 161                     // force the loop terminate with an error
 162                     n = -1;
 163                     srcLen = 1;
 164                 }
 165                 break;
 166
 167             default:
 168                 if ( end )
 169                 {
 170                     // nothing is allowed after the end so provoke error return
 171                     n = -1;
 172                     srcLen = 1;
 173                     break;
 174                 }
 175
 176                 in[n++] = c;
 177         }
 178
 179         if ( n == 4 )
 180         {
 181             // got entire block, decode
 182             decLen += 3 - padLen;
 183             if ( dst )
 184             {
 185                 if ( decLen > dstLen )
 186                     return wxCONV_FAILED;
 187
 188                 // undo the bit shifting done during encoding
 189                 *dst++ = in[0] << 2 | in[1] >> 4;
 190
 191                 // be careful to not overwrite the output buffer with NUL pad
 192                 // bytes
 193                 if ( padLen != 2 )
 194                 {
 195                     *dst++ = in[1] << 4 | in[2] >> 2;
 196                     if ( !padLen )
 197                         *dst++ = in[2] << 6 | in[3];
 198                 }
 199             }
 200
 201             n = 0;
 202         }
 203     }
 204
 205     if ( n )
 206     {
 207         if ( posErr )
 208         {
 209             // notice that the error was on a previous position as we did one
 210             // extra "p++" in the loop line after it
 211             *posErr = p - src - 1;
 212         }
 213
 214         return wxCONV_FAILED;
 215     }
 216
 217     return decLen;
 218 }
 219
 220 wxMemoryBuffer wxBase64Decode(const char *src,
 221                               size_t srcLen,
 222                               wxBase64DecodeMode mode,
 223                               size_t *posErr)
 224 {
 225     wxMemoryBuffer buf;
 226     wxCHECK_MSG( src, buf, wxT("NULL input buffer") );
 227
 228     if ( srcLen == wxNO_LEN )
 229         srcLen = strlen(src);
 230
 231     size_t len = wxBase64DecodedSize(srcLen);
 232     len = wxBase64Decode(buf.GetWriteBuf(len), len, src, srcLen, mode, posErr);
 233     if ( len == wxCONV_FAILED )
 234         len = 0;
 235
 236     buf.SetDataLen(len);
 237
 238     return buf;
 239 }
 240
 241 #endif // wxUSE_BASE64